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FACTORS AFFECTING FAT OXIDATION AND THE CHANGE IN FAT CONSTANTS WITH VOLUME OF OXYGEN ABSORBED

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THE PENNSYLVANIS STATE COLLEGE
THE GRADUATE SCHOOL
DEPARTMENT OF AGRICULTURAL AND BIOLOGICAL CHEMISTRY
FACTORS AFFECTING FAT OXIDATION AND THE CHANGE
I tS FAT CONSTANTS WITH VOLUME OF OXYGEN ABSORBED
A THESIS
BY
MARY LOUISE SHANER
SUBMITTED I N PARTIAL FULFILLMENT
FOR THE DEGREE OF
DOCTOR OF PHILOSOPHY
APPROVED
APPROVED 3
May 1 8 , 1 9 4 0
' May
I
1 8 , 1940
ACKNOWLEDGMENT
The a u t h o r w i s h e s t o t h a n k Dr„ H. 0 , T r i e b o l d
for h is
h e lp fu l
s u g g e s t i o n s and c r i t i c i s m s
cou rse o f t h i s w ork.
d u r in g th e
She a l s o w i s h e s t o th an k
Mr. M. H . M e r a k e r f o r h i s r e a d y a s s i s t a n c e .
T a b le o f C o n te n ts
H is to r ic a l T h e o r e tic a l - A u to x id a tio n - - - - - - - - - - - - - l
»
M ila s
Theory - - -
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2
M ethods o f S t u d y i n g A u t o x i d a t i o n R e a c t i o n s - - - - - - - - - -
7
C r ite r ia fo r A u to x id a tio n R e a c tio n s - - - - - - - - - - - - - - 9
A u to c a ta ly sis
S u sc e p tib ility
- - - - - - - - - - - - - - - - - - - - - - - - - 9
o f A u to x id a tio n R e a c tio n s - - - - - - - - - - - 1 0
P o s itiv e C a ta ly sts - - - - - - - - - - - - - - - - - - - - - - 1
0
N eg a tiv e C a t a ly s t s - - - - - - - - - - - - - - - - - - - - - -
11
Moureu an d D u f r a i s s e
»
s Theory - - - - - - - - - - - - - - - -
12
T h eo ries o f A u to x id a n t A c tio n - - - - - - - - - - - - - - - -
14
N o n -C a ta ly tic T heory o f A u t o x id a n t A c t i v i t y - - - - - - - - -
15
T h e o r i e s I n v o l v i n g C a t a l y t i c M e c h a n ism - - - - - - - - - - -
16
f
M ila s
9
O b j e c t i o n t o M ou reu an d D u f r a i s s e s T h e o r y - - - - - -
20
A u t o x id a tio n and In d u ce d O x id a t io n - - - - - - - - - - - - -
22
A u t o x i d a t i o n and P o l y m e r i z a t i o n - - - - - - - - - - - - - - -
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A u t o x i d a t i o n an d S t r u c t u r e - - - - - - - - - - - - - - - - -
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C la s s i f i c a t i o n o f A u to x id a tio n R e a c tio n s - - - - - - - - - 24
1
Coe s P h o t o c h e m i c a l T h e o r y - - - - - - - - - - - - - - - - - - 2 6
H is t o r ic a l E x p erim en ta l - R a n c id ity
- - - - - - - - - - - - -
35
F a cto rs I n flu e n c in g O x id a tio n - - - - - - - - - - - - - - - -
37
H eat - - - - - - - - - - - - - -
------ - - - - - -
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W ater
33
M eta ls
40
B a c t e r i a , M o l d s , E n zy m es - - - - - - - - - - - - - - - - - - -
40
G ases -
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A cid s -
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42
P ro -o x id a n ts - - - - - - - - - - - - - - - - - - - - - - - - - 4 6
A n ti-o x id a n ts - - - - - - - - - - - - - - - - - - - - - - - -
47
O th e r F a c t o r s - - - - - - - - - - - - - - - - - - - - - - - -
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O x id a tio n o f F a ts - - - - - - - - - - - - - - - - - - - - - -
50
O x id a tio n o f O le io A c id - - - - - - - - - - - - - - - - - - -
52
T em p eratu re o f O x i d a t i o n o f O l e i c A c id - - - - - - - - - - - - 5 7
T a s t e and Odor - - - - - - - - - -
- - - - - - - - - - - - - -
58
K r e is T e s t - - - - - - - - - - - - - - - - - - - - - - - - - - 6 0
O x id a tio n o f L i n o l e i c
and L i n o l e n i c A c i d - - - - - - - - - - - 6 3
M ethod o f R e c o g n i z i n g R a n c id F a t s - - - - - - - - - - - - - -
64
S ta te m e n t o f P rob lem -
74-
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D e s c r ip t io n o f A p p aratu s - - - - - - - - - - - - - - - - - - - 7 4
O p era tio n o f A pp aratu s - - - - - - - -
- - - - - - - - - - - - 7 8
T em p eratu re S tu d y - - - - - - - - - - - - - - - - - - - - - -
84
P r e s s u r e S tudy - - - - - - - - - - - - - - - - - - - - - - - - 8 5
E f f e c t o f A c id s - - - - - - - - - - - - - - - - - - - - - - -
88
A lc o h o l E x t r a c t i o n o f Lard - - - - - - - - - - - - - - - - - - 9 4
O x id a tio n o f P ure F a t t y A cid s
E ffect
- - - - - - - - - - - - - - - -
101
o f G a s e s on t h e O x i d a t i o n o f L a r d - - - - - - - - - -
A b s o r p t i o n o f D e f i n i t e V o lu m e s o f O x y g e n b y O i l s and F a t s
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11 0
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L ard B u tt e r f a t - - -
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C r isc o - - - - - - - - - - - - - - - - - - - - - - - - - - -
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O liv e O il -
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C otton seed O il - - - - - - - - - - - - - - - - - - - - - - -
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L in see d O il - - - - - - - - - - - - - - - - - - - - - - - -
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Summary - - - - - - - - - - - - - - - - - - - - - - - - - -
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B ib lio g r a p h y - - - - - - - - - - - - - - - - - - - - - - - -
1 25
HISTORICAL
I
THEORETICAL
-
A u to x id a tio n
Many a t t e m p t s
h a v e b e e n made t o
e x p l a i n t h e p h en o m en o n
o f a u to x id a tio n w h ich , by d e f i n i t i o n ,
i s th e
s t a n c e by m o l e c u l a r o x y g e n .
e x p l a n a t i o n s -were g i v e n b y
E n g l e r and W ild ( 1 8 9 7 )
E a r lie st
o x id a tio n o f a sub­
an d b y B a c h ( 1 8 9 7 ) an d t h e s e w e r e l a t e r
s u b s t a n t i a t e d by B a e y e r and V i l l i g e r
(1 9 0 0 ).
sim p le a d d i t i o n o f m o le c u l a r o x y g e n t o
t o fo r m a h i g h l y r e a c t i v e p e r o x i d e .
T h ey s u g g e s t e d t h e
an a u t o x i d i z a b l e
su b stan ce
T h is th e o r y f a i l e d
to
e x p la in
t h e o x i d a t i o n o f a l a r g e number o f c o m p o u n d s , s u c h a s a l c o h o l s ,
p h e n o ls,
fo rm .
e t c . w here i s o l a b l e
o r g a n ic p e r o x id e s a p p a r e n tly d id n ot
T h i s d i s c r e p a n c y , p l u s t h e t e n d e n c y o f t h e s e com pounds t o
l o ^ s e h y d r o g e n a to m s t o
form w a t e r or h y d ro g en p e r o x i d e ,
and t h e
a d d i t i o n a l f a c t t h a t t h e y c o u l d b e o x i d i z e d by o t h e r o x i d i z i n g
a g e n t s i n t h e a b s e n c e o f m o l e c u l a r o x y g e n l e d W ie la n d
and 1 9 1 4 ) , Dalcin ( 1 9 2 1 )
and D i x o n ( 1 9 2 5 and 1 9 2 7 )
id e a t h a t th e p r o c e s s was e s s e n t i a l l y
19 13
su g g e st th e
a d e h y d r o g e n a tio n w ith hydro­
g e n a to m s r a t h e r t h a n m o l e c u l a r o x y g e n p l a y i n g t h e
The d e h y d r o g e n a t i o n o f t h e a u t o x i d a n t i s
iv a t io n o f th e h yd rogen a tom s.
to
(1 9 1 2 ,
im p o rta n t r o l e .
t h e n f o l l o w e d by a n a c t ­
S h o u ld th e a u t o x id a n t be d e f i c i e n t
i n h y d r o g e n , Y /ie la n d a s su m e d t h a t w a t e r w o u ld add t o t h e a u t o x i d ­
ant b e fo r e d e h y d r o g e n a tio n to o k p l a c e .
j
The c h i e f o b j e c t i o n t o W i e l a n d s t h e o r y l i e s
fa c t th a t
oxygen.
it
does not accou n t fo r
P o ssib ly
o x id a tio n s e f f e c t e d
in th e
by m o l e c u l a r
d e h y d r o g e n a t io n s o c c u r as se c o n d a r y r e a c t i o n s
2
betw een t h e p r i m a r y p r o d u c t s o f a u t o x i d a t i o n and t h e
su b strate.
I t w o u l d t h u s s e e m t h a t t h e i n t e r p r e t a t i o n g i v e n by E n g l e r a n d
Bach a c c o u n t s f o r t h e g r e a t e r n u m b e r o f a u t o x i d a t i o n r e a c t i o n s .
This i s
s u b s t a n t i a t e d by t h e i s o l a t i o n o f some t r u e o r g a n i c p e r ­
ox id es from a u t o x i d a t i o n r e a c t i o n s .
One i m p o r t a n t c r i t e r i o n o f
»
a u to x id a tio n is th e s u s c e p t i b i l i t y to
in h ib ito ry actio n .
W ieland s
th e o ry does n ot e x p la i n t h i s as d e h y d ro g e n atio n r e a c t i o n s a re very
little
or not at a l l su sc e p tib le to in h ib ito ry actio n .
O t h e r im ­
po rtan t c r i t e r i a
are th e s u s c e p t i b i l i t y to th e a c c e le r a tin g a c tio n
of certe.in ty p e s
of re a g e n ts and c a p a b i l i t y
of inducing o x id a tio n
o f o t h e r s u b s t a n c e s w h i c h do n o t o r d i n a r i l y o x i d i z e w i t h m o l e c u l a r
»
o x y g e n ( W i e l a n d s t h e o r y f a l l s down h e r e ) . The E n g l e r - B a c h t h e o r y
doe3 n o t a d e q u a t e l y e x p l a i n n e g a t i v e
aly tic
e f f e c t of p eroxides
th is peroxide theory
cataly sis,
the p o s itiv e
cat­
and o t h e r p o s i t i v e c a t a l y s t s n o r i s
e v i d e n t f r o m p r o m o t e r a c t i o n a nd i n d u c e d o x i d ­
atio n .
To a c c o u n t f o r t h e r e q u i r e m e n t s de ma nded by a u t o x i d a t i o n
reactions,
M ilas
au to x id atio n .
(1929) p ro p o se d h i s
electro n ic
i n t e r p r e t a t i o n of
T h i s i n t e r p r e t a t i o n was b a s e d on h i s i n v e s t i g a t i o n
of th e p o ssib le e le c tro n ic
c o n f i g u r a t i o n o f oxygen and a u t o x i d a n t
which gave e v id e n c e of th e
a d d i t i o n o f oxygen i n th e m o le c u la r
f orm.
M i l a s made t h e f o l l o w i n g a s s u m p t i o n :
a t i o n s t h e atom s t o w hich t h e
be r e g a r d e d a s m a k i n g d e f i n i t e
it".
The r e s u l t i n g
" I n call a u t o x i d ­
oxygen m o le c u le i n i t i a l l y
co n trib u tio n s
a d d s may
o f two e l e c t r o n s t o
ayygen**oornpound^sc a l l e d a " d a t i v e p e r o x i d e " .
(The term, " d a t i v e " i s u s e d t o d e n o t e a t y p e o f c o v a l c n c y i n w h i c h
on e o f t h e a t o m s i n t h e
From h i s
d a t i v e bond c o n t r i b u t e s b o t h e l e c t r o n s . )
s t u d i e s a nd a n a l y s e s
of o t h e r p u b l i s h e d m a t e r i a l Llilas
concluded t h a t m o l e c u l a r oxygen r e a c t s
by s h a r i n g two e l e c t r o n s
w ith o th e r m o le c u le s t o form m e t a - s t a b l e
or d a tiv e peroxides
w hich a re c h a r a c t e r i z e d w i t h h ig h i n s t a b i l i t y
"Owing t o t h e i r h i g h i n s t a b i l i t y ,
re v e rt in s ta n ta n e o u s ly to the
t h e i r excess
energy t o
and e n e r g y c o n t e n t .
t h e s e p e r o x i d e s may e i t h e r
o r d i n a r y p e r o x i d e s by t r a n s f e r r i n g
o th e r m olecules,
or in itia te
th e oxidation
of other m o le c u le s."
T h u s o n l y w he n u n s h a r e d o r " e x p o s e d " e l e c t r o n s ,
parable t o th e v alen c e e le c tr o n s of v a rio u s elem en ts,
by a n a u t o x i d a n t , c a n a u t o x i d a t i o n t a k e p l a c e .
e l e c t r o n i c b a n d s Hu 1 l i k e n
(1925) and B i r g e
are possessed
In th e ir
(1926)
com­
s tu d y of
shov/ed t h a t t h e
energy l e v e l s
a s s o c i a t e d w i t h v a le n c e e l e c t r o n s o f m o le c u les ore
♦
a n a l o g o u s i n a l l e s s e n t i a l a s p e c t s w i t h t h e v a l e n c e e l e c t r o n s of
atom s.
-Thus m o l e c u l a r v a l e n c e e l e c t r o n s a r e
in a series of e le c tro n ic
of electro n s
states.
are c a lle d th e
c a p a b le of e x i s t i n g
The t w o l o n e o r u n s h a r e d p a i r
"m olecular v a le n c e e3.ectrons".
The f a c t t h a t d i f f e r e n t c o n d i t i o n s
are necessary fo r
a u t o x i d a t i o n o f co m p o u n d s p o s s e s s i n g u n s h a r e d e l e c t r o n s and u n s a t ­
u r a t e d l i n k a g e s may b e a c c o u n t e d f o r by t h e d i f f e r e n t
"penetration"
le v e ls o f th e m olecular valence e le c tr o n s ,
th e e f f e c t iv e nuclear
c h a r g e o f t h e p a r e n t a t o m and t h e s t a b i l i t y
o f t h e "unprom oted"
shared e le c tr o n s
in th e a u to x id an t m olecule.
By b l o c k i n g t h e m o l e c u l a r v a l e n c e e l e c t r o n s w i t h o t h e r
a t o m s , t h e m o l e c u l e b e c o m e s m ore i n e r t t o w a r d o x y g e n .
A t y p i c a l ex a m p le o f t h e
a u t o x id a t io n o f an u n s a tu r a te d
compound may b e s e e n i n t h e f o l l o w i n g
H H
R:C::C:R' 5=s
H H
RsCsCsR*
+
e q u a tio n ss
H H
R:CJ |C :R
*0:0
H H
R:C:C :R
:0:0 s
HH ,
RsC sC :R
02 ( a c t i v e )
(A ) an d (B )
(B)
In c a s e
(1)
th e a c t iv e
+ R :C ::C :R
RCHO + RCHO
a r e r e s o n a n c e form s o f ( C ) .
o x y g en form ed w i l l r e a d i l y
a c t upon t h e
o t h e r com p ou n ds w h i c h a r e i n e r t t o m o l e c u l a r o x y g e n .
In c a se
(2 )
th e a ld e h y d e s can be o x i d i z e d t o t h e c o r r e s p o n d in g a c i d s .
S p e c t r o s c o p i s t s h a v e fo u n d from t h e
band s p e c t r a t h a t t h e t o t a l
en erg y o f a m o le c u le i s
t h e e n e r g y due t o t h e t r a n s i t i o n s
c illa to r y
of e le c tr o n ic
of
com posed o f
o r b it s , th e
os­
e n e r g y o f n u c l e a r v i b r a t i o n s and t h e r o t a t i o n a l e n e r g y
as a w h o le .
M o le c u la r v a le n c e
e l e c t r o n s s h o u l d b e m ore e a s i l y
a f f e c t e d by e n v i r o n m e n t a l d i s t u r b a n c e s ,
lo o se ly
in te r p r e ta tio n
b ound t o t h e m o l e c u l e .
i o n s fr o m n e i g h b o r i n g m o l e c u l e s
a tu re e f f e c t ,
etc.
s in c e th ey
T hese d is tu r b a n c e s in c lu d e c o l l i s ­
or e le c tr o n s ,
T h e r e fo r e ," th e f i r s t
i n an y c h e m i c a l r e a c t i o n i s
by e n v i r o n m e n t a l f o r c e s " .
th e
a r e m ore
r a d ia tio n s,
tem p er­
c h a n g e w h i c h may o c c u r
change o f e le c t r o n ic
energy caused
In o rd er t o m a in ta in e q u ilib r iu m , th e r e
i s a n i m m e d i a t e c h a n g e i n v i b r a t i o n a l and r o t a t i o n a l e n e r g i e s o f
th e m o le c u le .
I t w as A r r h e n i u s w ho f i r s t
be a c t i v a t e d
b efore th ey
a u to x id a n ts,
a c tiv a tio n
r e a l i z e d t h a t m o l e c u l e s m u st
can undergo r e a c t i o n .
and d e - a c t i v a t i o n
In th e ca se
of
o f m o le c u le s a re governed
5
by two e n e r g y c o n c e p t s :
ence e l e c t r o n s , t h a t
(l)
i s , t h e en erg y l e v e l o f tlie e l e c t i o n s
d e fin ite equilibrium s ta t e ,
m olecules,
Th e p e n e t r a t i o n o f t h e m o l e c u l a r v a l ­
determ ines th e
at a
existence of a c tiv a te d
( 2 ) The t r a n s f e r o f e n e r g y among m o l e c u l e s i s
governed
u n d e r o r d i n a r y c o n d i t i o n s by c h a n g e s o f t h e l o o s e l y b o u n d m o l e ­
c u lar valence
electro n s.
L e t A: r e p r e s e n t a m o l e c u l e o f a n a u t o x i d a n t a n d
energy of a c t i v a t i o n .
, the
D u r i n g t h e a u t o x i d a t i o n o f A: t h e ' f o l l o w i n g
r e a c t i o n may o c c u r :
A:
A
ei
+
:
e-j_ —^
+
A
0*0*
Here e g i s t h e e n e r g y due t o t h e
s
e „
A :b :0 :(ei
+ eg)
i n s t a n t a n e o u s n e u t r a l i z a t i o n by
ox yg e n o f t h e a c t i v a t e d m o l e c u l e A
__ : .
Due t o t h e a b s o r p t i o n
of energy eg, t h e p r i n c i p a l quantum numbers o f t h e e l e c t r o n s
re­
s p o n s ib le f o r t h e f o r m a ti o n o f t h e d a t i v e p e r o x id e have b e en i n ­
c re a se d . M olecules of t h i s
easily
d isso ciated .
n a t u r e a r e e x t r e m e l y u n s t a b l e and
T h e i r r e a c t i v i t y may be s e e n f r o m t h e
ease
w i t h w h i c h r e a r r a n g e m e n t a nd e v e n d e c o m p o s i t i o n o f t h e d a t i v e
peroxide o c c u r s .
then i n i t i a t e s
The l i b e r a t e d
energy
(C hristianson
(1924))
re a c tio n chains.
^ 0
A: 0 : 0 ; ( e i
+ eg )
+
:-A -^s-
I
A
+
A s g >.:
^ 0
eg i s t h e
sum o f
+ eg«
This i n c r e a s e
of en erg y c o n t i n u e s v/ith
each s u b s e q u e n t r e a c t i o n c h a i n .
Should an i n h i b i t o r c o l l i d e v /ith t h e d a t i v e
th e e nergy of th e
peroxide,
l a t t e r w i l l b e a b s o r b e d by t h e m o l e c u l a r v a l -
ence e l e c t r o n s
of th o i n h i b i t o r .
broken and t h e r a t e
h ibitors
Thus t h e r e a c t i o n
of a u to x id a tio n i s
chain is
g re a tly reduced.
A ll in -
of a u t o x i d a t i o n p o s s e s s m o le c u la r e l e c t r o n s w hich a re
A
probably a t d i f f e r e n t p e n e t r a t i o n s .
The e n e r g y e x c h a n g e b e t w e e n
i n h i b i t o r and d a t i v e p e r o x i d e t a k e s p l a c e i n s t a n t a n e o u s l y e i t h e r
by e l e c t r o n i c i m p a c t s o r by e m i s s i o n a n d r e - a b s o r p t i o n o f i n v i s ­
i b l e r a d i a t i o n a nd i n e v i t a b l y
in h ib ito ry
a c tio n ta k es place.
O x i d a t i o n o f t h e a c t i v a t e d m o l e c u l e s o f t h e i n h i b i t o r by o r g a n i c
p e r o x i d e s o r by f r e e o x y g e n may o c c u r ,
or a com bination w ith a c t ­
i v e a u t o x i d a n t m o l e c u l e s may t a k e p l a c e w i t h t h e
fo rm a tio n of un­
s t a b l e c o m p l e x e s w h i c h on d e c o m p o s i t i o n , y i e l d t h e
i t o r m olecule.
o rig in al inhib­
The p r o m o t e r a c t i o n on a u t o x i d a t i o n may b e e x p l a i n e d
by a s s u m i n g t h a t t h e e n e r g y o f t h e v a l e n c e e l e c t r o n s
of th e p r o ­
m oter is
tra n s fe rre d to the in a c tiv e au to x id an t.
d irectly
or i n d i r e c t l y t h r o u g h t h e f o r m a tio n o f an i n t e r m e d i a t e
d ativ e peroxide
T h i s may o c c u r
of th e p ro m o te r.
The i n h i b i t o r y a n d a c c e l e r a t i n g a c t i o n p r o d u c e d by s m a l l
am ounts o f m a t e r i a l s
l a t t e r may
on a u t o x i d a t i o n a n d t h e i n d u c e d e f f e c t o f t h e
bei l l u s t r a t e d
A:
in th e fo llo w in g equations:
+
— >• A _ a 3_ 51. :
A__jaj_»-:
(In h ib ito r
action)
+
0:0: —»
A :0 " :0 :(ei + eg)
A :b :0 :( e< L + e g)
A
( +
V°
B
+ :B —
a g ^ : - » ( a ) A:
\
(b)
A=0
A
I + B
N 0
BOg
+
+
B=0
B = in h ib ito r
(a)
= rev ersib le
eq u atio n under fa v o ra b le c o n d itio n s
(b)
= irrev e rsib le
e3
(P ro m o ter a c t i o n )
As
+
G
m;
—»- A
e^ r t
+
C;
or
C
:
+
—>- C s d s O s ( e ^ + e g )
Os Os
and
C :0:*0s ( +
eg)
+
sA
Cs 0:0 s ( e i
+ eg)
+
A
—> Gs
+
AOg
+
+ ©2
or
A c c o r d in g t o M ila s
a n is m o f a u t o x i d a t i o n
a c tio n ,
r e a c tio n s
and t h e i s o l a t i o n
fo rm ed .
(19 32)
e
^
AOg + 2e^_ + e
a c o m p l e t e s t u d y o f t h e m ech­
sh o tild i n c l u d e t h e k i n e t i c s
and i d e n t i f i c a t i o n
of re­
o f t h e p rod u cts
The tw o g e n e r a l m e t h o d s o f s t u d y i n g a u t o x i d a t i o n r e a c t ­
io n s ares
I.
Q u a n t it a t iv e e s t im a t io n o f th e oxygen absorbed p er
u n it tim e .
II.
E stim a tio n
o f th e
d isa p p e a r a n c e o f t h e a u to x id a n t
or t h e p r o g r e s s iv e fo r m a tio n o f th e p r in ­
c ip le
I.
p ro d u cts o f th e r e a c tio n per u n it tim e .
M e th o d s o f d e t e r m i n i n g O xy gen A b s o r p t i o n :
T h is i n c l u d e s t h e v a r io u s m o d if i c a t i o n s
m eth od s.
fo llo w e d
The r a t e
o f oxygen a b so r p tio n in a c lo s e d
i n tw o d i f f e r e n t w ays:
sta n t p ressure
T h i s m eth od ( b )
and ( b )
is
o f s t a t i c and staring
th e
(a )
by d e c r e a s e i n v o lu m e a t c o n ­
by d e c r e a s e i n p r e s s u r e a t
sim p le st
m eans t h e m o s t a c c u r a t e .
s y s t e m may b e
c o n s t a n t v o lu m e .
and m o s t c o n v e n i e n t way b u t by no
S in c e o x id a t io n o f an o r g a n ic l i q u i d
phase s y s t e m ,
c o n s t i t u t e s a tw o
t h e g a s an d l i q u i d m u s t b e i n c o n s t a n t e q u i l i b r i u m
w i t h e a c h o t h e r b e f o r e t h e r e a c t i o n r a t e may b e d e t e r m i n e d .
l i q u i d m ust a lw a y s be s a t u r a t e d w i t h
The
oxygen d u r in g th e r e a c t i o n .
C o n s i d e r a b l e c h a n g e s i n p r e s s u r e d u r i n g o x i d a t i o n may t e n d t o i n ­
flu e n c e th e r a te
o f o x y g e n a b s o r p t i o n and t h e g a s e o u s p r o d u c t s
w h ic h a r e f o r m e d may i n c r e a s e t h e p r e s s u r e o f t h e s y s t e m a l t h o u g h
t h e y may h a v e no i n f l u e n c e on t h e r e a c t i o n .
an a p p a r e n t d e c r e a s e
in th e r a te
d i t i o n s m u st b e c o r r e c t e d f o r i f
changes a r e b e s t
pressure.
T h i s w o u ld r e s u l t
o f oxygen a b s o r p tio n .
tru e ra tes
are d e sir e d .
in
T hese con ­
P ressu re
o v e r c o m e by r u n n i n g t h e e x p e r i m e n t a t a t m o s p h e r i c
D e a t h e r a g e and M a t t i l l
an a p p a r a t u s w h i c h o v e r c o m e s t h i s
(1939)
have r e c e n t ly r e p o r te d
p r e s s u r e i n c r e a s e by c o n t i n u a l l y
r e m o v in g t h e g a s e o u s p r o d u c t s b y c i r c u l a t i n g t h e o x y g e n t h r o u g h
a number o f a b s o r p t i o n t u b e s .
II.
O t h e r M e th o d s f o r D e t e r m i n i n g A u t o x i d a t i o n *
T h i s i n c l u d e s t h e d e t e r m i n a t i o n s o f c h e m i c a l and
p h y sica l c o n s ta n ts .
w ith tim e
is
The i n c r e a s e
one o f t h e
o l d e s t m eth od s known.
a t i l e p r o d u c t s may l e a d t o
of p e r o x id e s ,
a ld e h y d e s,
in c r e a se a lo n e i s
of a u to x id a tio n .
erroneous
esters,
c o n sid e r e d .
th e s e p r o d u c ts w ith tim e
i n w e ig h t o f th e a u to x id a n t
r e su lts
F o rm a tio n o f v o l ­
a s may t h e f o r m a t i o n
h y d r o x y com p ou n d s w hen t h e w e i g h t
H ow ever an e s t i m a t i o n o f ea c h o f
can b e u s e d
as a p a r t i a l i n t e r p r e t a t i o n
The i o d i n e n u m ber may b e f o l l o w e d i n t h e d e t e r ­
m in a tio n o f o x i d a t i o n r a t e s .
I n many c a s e s t h e o x i d a t i o n i s
a c c o m p a n ie d b y a p o l y m e r i z a t i o n o f t h e o i l an d t h e m e a s u r e m e n t s
w o u ld i n d i c a t e o n l y t h e c u m u l a t i v e e f f e c t ,
p e r o x id e s w o u ld g i v e i d e a l r e s u l t s
le a d t o
secon d ary r e a c t io n s .
e stim a tio n .
be a p p l i e d t o
S p e c tr o sc o p ic
if
A m easurem ent o f t h e
th ey w ere s t a b le
and d i d n o t
T h i s may b e u s e d a s a s e m i - q u a n t i t a t i v e
an d X - r a y s p e c t r o s c o p i c m e t h o d s a l s o may
a u to x id a tio n s t u d ie s .
In ord er t o
r e c o g n iz e a u to x id a tio n r e a c tio n s th e fo llo w ­
i n g c r i t e r i a may b e u s e d t o d i s t i n g u i s h th e m f r o m o t h e r c h e m i c a l
r e a c tio n s:
1,
A u to x id a tio n r e a c tio n s are
a u to c a ta ly tic ,
2,
T h ey a r e s u s c e p t i b l e t o p o s i t i v e a n d n e g a t i v e
c a ta ly sts,
3,
T hey i n d u c e t h e o x i d a t i o n o f o t h e r s u b s t a n c e s
r e l a t i v e l y u n a f f e c t e d by f r e e o x y g e n ,
4,
T h ey i n d u c e p o l y m e r i z a t i o n o f v a r i o u s a u t o -
oxidants,
5,
S u s c e p tib ility to
a u to x id a tio n
is
g o v e r n e d by t h e s t r u c t u r e
fr e q u e n tly
o f th e
a u to x id a n t,
1,
A utoxidation re a c tio n s are a u t o c a t a l y t i c :
I n d u c tio n P e r io d :
found t o be e x o t h e r m i c .
very s lo w ly , th en th e
A u to x id a tio n r e a c tio n s are g e n e r a lly
At th e b e g in n in g th e
speed in c r e a se s
u n t i l a maximum v e l o c i t y
is
a tta in e d .
r e a c tio n ta k e s p la c e
as a u to x id a tio n p roceeds
S h ould p o l y m e r i z a t i o n o c c u r
s i m u l t a n e o u s l y w i t h o x i d a t i o n , t h e r a t e may f a l l
o f f v ery r a p id ly
l o n g b e f o r e a n a p p r e c i a b l e am ount o f t h e a u t o x i d a n t h a s b e e n o x i d —
iz e d .
R e a c tio n s o f t h i s
n a tu re are a u to c a ta ly tic
type*
An o u t s t a n d i n g p r o p e r t y
of th e se r e a c tio n s i s
io n p e r io d w h ich M ila s d e f i n e s
io n to r e a c h i t s
s t i l l d eb ated *
and o f t h e c h a i n
t h e i r in d u c t­
as th e tim e n e c e s s a r y f o r th e r e a c t ­
maximum v e l o c i t y .
The c a u s e o f t h e p e r i o d i s
I t may b e c o n s i d e r e d
a s b e i n g due t o t h e
sta te
of
p u r i t y o f t h e a u t o x i d a n t and t h e i n c r e a s e o r d e c r e a s e o f t h e r e a c t ­
io n r a te i s
a ly sts.
c o n t r o l l e d by t h e p r e s e n c e o f p o s i t i v e
H olm , G r een b a n k and D e y s h e r ( 1 9 2 7 )
th a t t h is p e r io d i s
p o te n tia l.
t h e t i m e n e c e s s a r y t o b u i l d up a h i g h o x i d a t i o n
The e x p e r i m e n t a l e v i d e n c e o f f e r e d f r o m s t u d i e s
be due t o d i f f e r e n c e s i n
S u sc e p tib ility
of th is
T h i s may p o s s i b l y
e x p e r im e n ta l c o n d itio n s*
o f a u to x id a tio n r e a c tio n s to p o s it iv e
a tiv e
(a)
ca t­
o ffe r th e su g g e stio n
p r o p e r ty h ave le jld o n ly t o f u r t h e r c o n f u s i o n .
2.
or n e g a t iv e
and n e g ­
c a t a ly s t ss
P o s itiv e C a ta ly sts:
P o sitiv e
c a t a l y s t s may b e c l a s s i f ­
i e d as f o l l o w s :
1.
O r g a n ic c a t a l y s t s i n c l u d i n g p e r o x i d e s
and o z o n i d e s .
2.
In o r g a n ic
c a ta ly sts
th e ir
3.
1.
an d c o m p l e x e s .
R a d i a t i o n and h i g h f r e q u e n c y s o u n d w a v e s .
O rg a n ic c a t a l y s t s :
fo u n d t o b e o f t h e
s a lts
in c lu d in g m e ta ls ,
In t h i s
group, r e a c tio n s are
c h a in t y p e w it h t h e o r g a n ic c a t a l y s t a c t i n g as
a " tr ig g e r " , th a t i s ,
th e
c h a in o r i n c r e a s e s t h e i r
c a ta ly st
le n g th .
seem s t o i n i t i a t e
th e
r e a c tio n
2.
Inorganic c a ta ly s ts ;
found t o g iv e a v a r i e t y
Its c ata ly tic
of r e s u l t s ,
T h is group of r e a c t i o n s has been
e s p e c i a l l y i n th e case of iron*
a c t i v i t y v a r i e s i n i n t e n s i t y and s i g n d ep en d in g upon
the chem ical n a tu r e
o f th e c a t a l y s t and a u t o x i d a n t .
The m e c h a n i s m
of t h e r e a c t i o n i s assum ed t o be an i n i t i a l a c t i v a t i o n of oxygen
by t h e f o r m a t i o n o f a n i n t e r m e d i a t e i r o n p e r o x i d e .
An e x p l a n a t i o n
f o r t h e a u t o x i d a t i o n o f f e r r o u s co m p o u n d s m a y - l i e i n t h e f a c t t h a t
t h e f e r r o u s i r o n may c o m b i n e d i r e c t l y w i t h o x y g e n l i k e a f r e e r a d ­
ic a l because of i t s
tio n of f e r r o u s
salts
the ru le s a lre a d y
3.
lone m o le c u la r v a le n c e e le c tro n *
is
The o x i d a ­
an a u t o x i d a t i o n r e a c t i o n s in c e i t
obeys
set fo rth .
R a d i a t i o n and h ig h f r e q u e n c y sound waves:
recognized f a c t t h a t r a d i a t i o n s
s h o r t wave l e n g t h s ,
It
is a
a n d e s p e c i a l l y t h o s e p r o d u c e d by
a cc e lera te autoxidation re a ctio n s.
B&ckstrfJm
(1 9 2 7 ) h a s d e m o n s t r a t e d t h a t p h o t o c h e m i c a l o x i d a t i o n s a s ' w e l l a s
therm al o x id a tio n s a re s u s c e p ti b l e to th e
These r e a c t i o n s a r e e s s e n t i a l l y
(b)
N egative C a t a l y s t s :
propose a r e a s o n a b le th e o r y t o
a c tio n of i n h i b i t o r s .
chain r e a c tio n s .
L uther
(1903)
w as t h e f i r s t
ex p lain negative c a ta ly s is .
assumed t h a t t h e n e g a t i v e c a t a l y s t
or in h ib ito r
to
He
a c t s by d e s t r o y ­
ing th e p o s i t i v e c a t a l y s t s which a re o r i g i n a l l y p r e s e n t i n th e
t
autoxidizable
substance.
Mou reu a n d D u f r a i s s e b e l i e v e d L u t h e r s
t h e o r y i n a d e q u a t e w he n a p p l i e d t o t h e i r w o r k .
o f f e r e d was b a s e d on m u t u a l a n t a g o n i s t i c
o x i d e s by t h e i n t e r a c t i o n o f t h e
o rig in al
The t h e o r y t h e y
d e s t r u c t i o n of th e p e r ­
a c tiv e peroxide
of
a u t o x i d a n t an d t h e i n h i b i t o r .
*
Moureu a n d D u f r a i s s e s t h e o r y
w id e ly d is c u s se d t h e o r ie s in th e
work d on e d u r i n g t h e
a c r o le in .
war on t h e
(1 9 2 6 )
is
o n e o f t h e m ost
o x id a tio n f i e l d .
I t grew out o f
s ta b iliz a tio n
o f q u a n titie s
of
They f o u n d t h a t s m a l l a m o u n ts o f p h e n o l i c , com pounds
in h ib it e d th e fo r m a tio n
o f t h e s t a b l e r e s i n p o ly m e r j* d i s a c r y l fro m
a c r o le in .
C o n t i n u a t i o n o f t h i s w ork sh ow ed t h e n t h a t t h e r e w as a
g e n e r a lity
in ch aracter o f a n ito x id a tiv e
a c tio n .
They n o t e d t h r e e
s tr ik in g r e s u lts :
1.
A c e r t a i n c a t a l y s t may a c t e i t h e r
or a p r o - o x id a n t d e p e n d in g upon t h e c o n d i t i o n s
and n o t u p o n t h e n a t u r e o f t h e
c a tla y s t.
s t a n c e t o a c t as an a u t o x i d a t i v e
th a t th e
as a n a n t i o x i d a n t
o f t h e e x p erim en t
The a b i l i t y
c a ta ly st is
o f a sub­
t h e o n ly p r o p e r ty
s u b s t a n c e n e e d p o s s e s s w hen a c t i n g u p o n an o x i d i z a b l e
su b sta n ce.
2.
r e la te d to
S u sc e p tib ility
its
3.
c a ta ly tic
C a ta ly tic
m o le c u le w h ich i s
In p r in c ip le
o f a s u b s ta n c e to w a rd o x i d a t i o n i s
p r o p e r tie s.
a c tiv ity
is
lo c a liz e d
i n t h a t p a r t o f th e
o x id iz a b le un der th e g iv e n ex p erim en ta l c o n d it io n s .
an o x i d i z a b l e s u b s t a n c e no m a t t e r v /h at i t s
t o w a r d o x y g e n may b e
r e a c tiv ity
s h o u l d b e c a p a b l e o f a c t i n g a s an a u t o x i d a t i v e
c a t a ly s t under t h e p ro p er c o n d it io n s .
In t h e i r e x p e r i m e n t a l w ork t h e y f o u n d t h a t t h e i n t e n s i t y
of th e a c t iv it y
ce n tra tio n .
o f a n e g a tiv e
c a t a l y s t w as d e p e n d e n t upon t h e
I t w o u l d be e x p e c t e d t h e n t h a t t h i s
con­
a c t i v i t y w o u ld
13
la s t in d e fin ite ly
o x id iz a b le
but a c t u a lly
s u b s t a n c e and i t s
a c tiv ity
th e p ro cess o f a u to x id a tio n i s
or th e v e l o c i t y
th e a n tio x id a n t r e a c ts w ith th e
is
a c tu a lly
lo st.
To d e t e r m i n e w h e t h e r
s t o p p e d by t h e a n t i o x i d a n t
o f th e r e a c t i o n sim p ly d e c r e a s e d , th e p e r io d o f
o b s e r v a tio n was e x te n d e d .
Q u e s t i o n a b l e r e s u l t s w e r e o b t a i n e d and
no c o n c l u s i o n s c o u l d b e draw n a s c h a n g e s o c c u r r e d i n t h e r e a c t i o n
f l a s k s w h ich a l t e r e d t h e
e x p erim en ta l c o n d it io n s .
Some o f t h e
r e s u l t s w o u ld i n d i c a t e h o w e v e r t h a t t h e a b s o r p t i o n o f o x y g e n i s
n ever c o m p le te ly in h ib it e d .
An a u t o x i d i z i n g c a t a l y s t a s a l r e a d y s t a t e d c o u l d b e a
positiv e
cataly st.
I t w as f o u n d t h a t n u m e r o u s s u b s t a n c e s w h i c h
under ordinary c o n d itio n s are p r a c t i c a l l y
oxygen,
c o u ld be r e a d i l y o x i d i z e d i n t h e p r e s e n c e o f an a p p r o -
p iate c a ta ly s t.
The c a t a l y s t w h i c h i s t h e p r o - o x i d a n t ,
a u t o x i d i z e s , t h e n g i v e s up t h i s
iznble
in a c t i v e tow ard f r e e
substance.
first
oxygen t o th e d i f f i c u l t l y
The c a t a l y s t i s t h u s r e g e n e r a t e d i n i t s
i n a l u n o x id iz e d s t a t e and i s
oxido rig ­
c a p a b l e o f r e a c t i n g w i t h m or e f r e e
oxygen.
M oure u and D u f r a i s s e a l s o f o u n d t h a t a c a t a l y s t w o uld
a c t p o s i t i v e l y t o w a r d some m a t e r i a l s
th u s the s o - c a lle d
a nd n e g a t i v e l y t o w a r d o t h e r s ,
" in v e rs io n ” of c a t a l y s i s .
A c a t a l y s t which
a c t s as a p o w e r f u l a n t i o x i d a n t would a l s o a c t a s a p o w e r f u l p r o ­
oxidant.
ativ e,
Gases were a l s o o b s e r v e d where a c a t a l y s t a t f i r s t
neg­
changes to p o s i t i v e a f t e r a c e r t a i n le n g th of tim e .
S eco n d ary r e a c t i o n s were o c c a s i o n a l l y found t o ta k e
place during a u to x id n tio n .
T h e s e w e r e o b s e r v e d by t h e f o r m a t i o n
o f r e sin o u s p r o d u c ts,
ific a tio n .
Free
c o lo r p r o d u c tio n ,
oxygen i s
p r e c ip ita tio n
not r e s p o n sib le
fo r th ese
t h e c o m b in e d o x y g e n f r o m t h e p e r o x i d e w h i c h i s
a u to x id iz a b le
For t h i s
T h eo ries
c o n s id e r a tio n th e
The s t a b l e
to th e fo r m a tio n o f th e
sta b le
system ,
+
02
B is
is
th e c a ta ly s t
c a ta ly st
d ir e c tio n , th a t
is
is ,
a u to x id iz a b le
sta te
u n le ss
and i n t h i s
su b stan ce i s
o f th e system corresponds
energy i s
case is
in v e r se r e a c tio n
fu r n ish e d to th e
a n e g a tiv e
o f f o r m a t i o n o f A 02 »
one s i n c e
A c t u a lly th e term
a m is n o m e r i m p l y i n g a c a t a l y s i s i n t h e w r o n g
a c a ta ly s is
g i v i n g a r e a c t i o n an i m p u l s e i n t h e
d i r e c t i o n o p p o s i t e t o t h a t g i v e n by p o s i t i v e
a ly st is
fo r m e d fr o m t h e
o x i d e A02 s i n c e t h e
im p o ssib le
i t d ecrea ses th e v e lo c it y
n e g a tiv e
but
o f A n tio x id a n t A c tio n
a g a in d e s ig n a te d as A.
A
changes,
su b stan ce.
I
A02 —>
or r a n c id -
c a ta ly sis,
"No c a t ­
a b le v /ith o u t th e a d d it io n o f e x t e r n a l energy to r e v e r s e
th e c o u r se o f s p o n ta n e o u s c h e m ic a l r e a c t i o n s w h ich are a c c e le r a t e d
by p o s i t i v e
c a ta ly sts,
o f a system w ith o u t t h e
fo r i t
is
im p o ssib le to
r a is e th e p o te n tia l
e x p e n d i t u r e o f e n e r g y and t h e l a w s o f t h e r m o ­
d y n a m ic s r e q u i r e t h a t w h en a p h en o m en o n t a k e s p l a c e s p o n t a n e o u s l y
(th a t i s ,
tem )
it
w ith o u t th e a p p lic a t io n
o f e x te r n a l energy to th e s y s ­
a l w a y s t a k e s p la .c e w i t h l i b e r a t i o n
T hus i f
c a ta ly s is,
it
d r iv in g th e
th e a c t iv it y
o f e n e r g y ."
o f an a n t i o x i d a n t i s
m u st b e a p o s i t i v e
sy ste m tow ard a s t a t e
c a ta ly s is j th a t i s ,
o f e q u ilib r iu m
a c tu a lly
a
a c a ta ly sis
and t o a l o w e r
p o te n tia l le v e l,
A c a ta ly st
in a r e v e r s ib le
r e a c t i o n m ig h t be c a p a b le
o f p r o d u c i n g tw o i n v e r s e
d ir e c tio n i t
—■*— AO2
c h e m ic a l r e a c t i o n s d e p en d in g upon th e
d r iv e s th e r e a c tio n .
is
r e v e r sib le
H o w ev er t h e r e a c t i o n
and t h e r e f o r e t h e tw o i n v e r s e
; ■ t i o n s a r e i m p o s s i b l e and n o t a n a l o g o u s t o t h e
and a n t i - o x i d a n t s .
e n t m e c h a n is m t o
a n tio x id a n t a c t i v i t y ,
+
02
c h e m ic a l r e -
a c tiv ity
T h is n e c e s s i t a t e s th e a p p l i c a t i o n
A
o f pro-
of a d iffe r ­
a m e c h a n is m v /h ic h d e a l s w i t h
an e q u i l i b r i u m i m p e l l e d i n a s e n s e o p p o s i t e t o t h a t o f p r o - o x i d a n t
c a ta ly sis.
A.
N o n -c a ta ly tic th e o r y o f a n tio x id a n t a c t iv i t y :
The p o s s i b i l i t y
of p o sitiv e
th eo ry .
c a ta ly sts
h a s b e e n o f f e r e d a s an a i d i n
The p r e s e n c e o f t h e s e
a b le , y e t th e
itie s
th a t a u to x id a tio n r e q u ir e s th e p resen ce
a c tio n
su b sta n ces i s
e x p la in in g t h is
n o t a lw a y s d e m o n str a t-
of th e w a lls o f th e v e s s e l, tr a c e s
o f im p u r ­
and m o i s t u r e a p p e a r t o b e e s s e n t i a l i n many r e a c t i o n s .
»
T i t o f f s Theory:
T i t o f f (1903) reason ed th a t i f a u to ­
o x i d a t i o n w as c a u s e d by t h e p r e s e n c e o f t r a c e s
effect
c o u ld be n e u t r a l i z e d
o th er im p u r it ie s .
by t h e a d d i t i o n o f s m a l l a m o u n ts o f
He c o n c l u d e d t h a t
a n e g a tiv e
by s i m p l y p a r a l y z i n g t h e a c t i o n o f a p o s i t i v e
a m p le , by c o m p le x f o r m a t i o n ,
o f im p u r itie s , th is
c a t a ly s t acted
c a ta ly st,
etc.
T h i s e x p l a n a t i o n may h o l d f o r some i s o l a t e d
in g en era l i t
is
in a d e q u a te .
fo r ex­
c a s e s but
The o b j e c t i o n s may b e su m m a r ized
as f o llo w s :
1.
iz e d
V /ater c a n n o t b e t h e p o s i t i v e
sin c e a n tio x id a n ts
a e t i n aqueous s o l u t i o n .
are
c a t a l y s t w h ich i s
n o t d e h y d r a t i n g o .g e n ts and n ay a c t
n e u tr a l­
16
2.
The s u p p o s i t i o n v / o u l d h a v e t o b e made t h a t t h e m o s t d i ­
v e r s e s u b s t a n c e s s u s c e p t i b l e t o a u t o x i d a t i o n w o u l d owe t h e i r
c e p t i b i l i t y t o t h e p r e s e n c e o f t h e same i m p u r i t i e s o r a t
i m p u r i t i e s o f t h e same c a t a g o r y .
sus­
le a s t to
T h i s se e m s h i g h l y i m p r o b a b l e .
T i t o f f s th e o ry a l s o does not account f o r th e fo llo w in g
general p ro p e rtie s
1.
of a n t i o x i d a n t s :
O x i d i z a b i l i t y - a common p r o p e r t y o f a l l a . n t i o x i d a n ts as w ell
ativ e
2.
a s o.n e s s e n t i a l one f o r a n t i o x i d ­
activ ity .
A g i v e n c a t a l y s t may a c t a s a n a n t i o x i d a n t o r a. p r o ­
o x i d a n t d e p e n d i n g on t h e c o n d i t i o n s
of the
reactio n s«
B.
T h e o r i e s i n v o l v i n g a c a t a l y t i c mechanism:
If an tio x id ativ e a c tiv ity
is a cataly sis,
i t must n e c ­
e s s a r i l y be p o s i t i v e a n d i t m u s t be c o n c e d e d t h a t t h e phen ome non
of a u t o x i d a t i o n o f A doe3 n o t c o n s i s t i n a c o n t i n u a l dro p of p o t t e n t i n l of th e system A
+
02 u n til
oxidation is
com plete.
F h y s i c a l a n d c h e m i c a l o b s e r v a t i o n s h a v e b e e n shown t h a t
a l l m olecules
o f a. d e f i n i t e
s p e c ie s i n e i t h e r a l i q u i d o r gaseous
f o r m a r e n o t i n t h e same e n e r g y s t a t e .
u a l m olecules a re d i s t r i b u t e d
t i o n of th e m olecules
difference
The s t a t e s o f t h e i n d i v i d ­
a r o u n d a mean s t a t e a n d t h e p r o p o r ­
in a given
f r o m t h e mean s t a t e .
s t a t e v a r i e s in v e r s e ly v/ith th e
Those m o le c u le s i n a s t a t e
t h a n t h e mean s t a t e a r e a c t i v a t e d a n d i t
is
only* t h e s e a c t i v a t e d
m o le c u le s v/hich c a n u n d e rg o c h e m i c a l r e a c t i o n .
of th e
reactio n is
regulated
other
Thus t h e v e l o c i t y ' '
by t h e p r o p o r t i o n o f a c t i v e m o l c c i u . e s
17
and "by t h e s p e e d w i t h w h i c h t h e y a r e f o r m e d i n t h e m a s s .
ivated s t a t e
energy.
This a c t ­
i s a c q u i r e d by a m o l e c u l e a t t h e e x p e n s e o f t h e a v e r a g e
Average m o le c u le s have an en erg y l e v e l d e s i g n a t e d as
$
t h o s e m o le c u le s w h ic h r e a c t must p a s s t h r o u g h e n e r g y l e v e l E2 (a n
activated s ta te of h igher p o te n tia l)
b e f o r e d e sc e n d in g to energy
l e v e l E3 ( a l e v e l l o w e r t h a n Ej_) w h i c h i s t h e s t a b l e
autoxidation,
state
of
When p a s s i n g t h r o u g h l e v e l E s , two c a t a l y t i c p r o ­
cesses are p o s s ib le ,
both p o s itiv e
of which t h e
m e tric a lly o p p o site $ one, p ro - o x id a tiv c
t o E3 } t h e o t h e r ,
e ffe c ts are d ia ­
a c t i o n f a v o r i n g movement
a n t i o x i d a t i v e a c t i o n f a v o r i n g r e t u r n t o E1 .
T h i s e x p l a i n s why a v e r y s m a l l nu mb er o f m o l e c u l o s o f
a n a n t i o x i d a n t c a n p r e v e n t o x i d a t i o n o f a. v e r y l a r g e numb er o f
m o l e c u l e s o f an a u t o x i d i z a b l e
(i.
e , , the re a c tio n is
s u b s t a n c e i n c o n t a c t w i t h oxygen
d e p e n d e n t on t h e numb er o f ' a c t i v a t e d m o l e ­
cules p r e s e n t) .
D irect In a c tiv a tio n
By d e c r e a s i n g
cules
of a s p e c i e s ,
p o rtio n ally ,
the
c o n c e n t r a t i o n o f t h e a c t i v e m ole­
t h e r e a c t i o n v e l o c i t y v/ou ld be d e c r e a s e d p r o ­
Thus i t n a y b e c o n c e i v e d t h a t t h e a n t i o x i d a n t B a c t s
in c a ta ly z in g th e r e tu r n of a c tiv e m olecules,
e i t h e r of th e n.nti-
o x i d a n t A o r o f o x y g e n t o t h e i r mean e n e r g y l e v e l .
Hugh S . T a y l o r ( 1 9 2 3 ) p r o v e d t o s. c e r t a i n e x t e n t t h a t
a n a n t i o x i d a n t a c t e d by
oxidant,
H ow ev e r t h i s
fo rm in g m o le c u la r com plexes v/ith th e a n t i ­
th e o ry does not c o n c lu s iv e ly prove th e
p o i n t a nd i t h a s b e e n s u p p l e m e n t e d by f u r t h e r w ork o f l.ioureu a nd
D ufraisse,
The e s s e n t i a l c o n d i t i o n i s t h e u n i o n o f t h e c a t a l y s t
w i t h t h e a c t i v e m o l e c u l e s a n d n o t w i t h t h e mass o f m o l e c u l e s i n
t h e mean s t a t e .
activ ity .)
( S t a b l e com plexes would have l o s t t h e i r
cataly tic
When one o f t h e a u t o x i d i z a b l e m o l e c u l e s e n t e r s i n t o
the r o a c tio n ,
th e a n tio x id a .n t must re a c h i t
to act before ir r e p a r a b le
im m ediately
in ju r y has r e s u lte d .
in order
"T his r e s u l t can
o n l y be o b t a i n e d by a m a r k e d p o w e r o f s e l e c t i v e a t t r a c t i o n w h i c h
apparently is in d isp e n sa b le f o r a n tio x id a tiv e
a ctiv ity ."
This sim ple i n a c t i v a t i o n of a u to x i d i z a b l e s u b sta n c e s
d o e s -not e x p l a i n a l l t h e c a s e s o f a n t i o x i d a t i v e a c t i o n .
The w i d e
v a r i e t y o f a n t i o x i d a n t s v/o u ld n o t a l l a c t t h e same u p o n a s i n g l e
autoxidizable
substance.
In d irect In activ atio n
Mo ureu a n d D u f r a i s s e a g r e e w i t h t h e m a j o r i t y o f a u t h o r s
t h a t a u t o x i d a t i o n s t a r t s w i t h t h e u n i o n o f a n o x y g e n m o l e c u l e and
a m olecule of th e a u t o x i d i z a b l e su b sta n c e A t o form th e prim ary
p e ro x id e A(02 ) .
it
( I n A(02 ) t h e oxygen in b r a c k e t s i n d i c a t e s t h a t
is p re se n t in anjactivated 3 t a t e .)
This p e ro x id e a cc o rd in g to
Moureu a n d D u f r a i s s e a n d c o n t r a r y t o t h e i r p r e d e c e s s o r s ,
v/ith an a b s o r p t i o n o f r a t h e r t h a n a l i b e r a t i o n o f e n e r g y .
i s formed
The p e r ­
oxide i s form ed from a c t i v e A and oxygen m o le c u l e s and v e r y l i t t l e
energy i s
lo st.
T h e s e men d r e w t h e c o n c l u s i o n t h a t t h e a u t o x i d a n t s must
act in cataly zin g th e in v erse re a c tio n ,
t h e p e r o x id e A(02 ) .
i.
e .,
t h e d e s t r u c t i o n of
Thus t h e com bined oxygen i s
lib e ra te d rapidly
an d c o m p l e t e l y a s s u b s t a n t i a t e d i n t h e m u t u a l d e s t r u c t i o n o f p e r ­
oxides.
T h is i s
t h e i r p r o p o s e d m e c h a n is m o f t h e a c t i o n o f a n t i ­
o x id a n ts:
T he p e r o x i d e A ( 0 2 ) o x i d i z e s t h e a n t i o x i d a n t B, v / i t h t h e
fo r m a tio n o f B(0)
an d i s
i t s e l f tra n sfo rm ed in t o th e p e r o x id e A (0 ),
The p e r o x i d e s A ( 0 ) an d B ( 0 )
are a n ta g o n is tic
and m u t u a l l y d e s t r o y
e a c h o t h e r w i t h r e g e n e r a t i o n o f t h e o r i g i n a l m o l e c u l e s A , B, and
aygen i n t h e i r
o r ig in a l s ta te .
T h i s may b e e x p r e s s e d i n t h e e q u a t i o n f o r m a s f o l l o w s *
A
Og
+
A ( o2 )
A (0)
*“ A ( 0 2 )
+
+
B —
A ( 0)
B( 0 ) —— A
P o ssib le d ir e c t a u to x id a tio n
+
02
B
+
0 2 *— B ( 0 S )
+
B(0)
+
B
+
02
o f t h e a n t i o x i d a n t may t a k e p l a c e :
A
A(02)
+
A (02 )
B(0g) —
A
+
B
+
20g
Thus t h e m o l e c u l e s A and 0 2 a r e t a k e n f r o m t h e a c t i v a t e d
sta te
a t t h e moment t h e y c o m b in e and a r e r e t u r n e d t o t h e m i x t u r e u n ­
a c tiv a te d ,
a ly sis
Tn r e a l i t y t h e n e g a t i v e c a t a l y s i s
s in c e
it
is
a p o sitiv e
ca t­
fa v o rs a p o t e n t ia l drop.
O t h e r r e a c t i o n s may o c c u r i n t h e a b o v e manner*
Two a u t o x i d i z a b l e
su b sta n ces in
as a n tio x id a n ts t o
each o th er:
+ A(0) -
A( 0 ) +
S h o u ld t h e p e r o x i d e B ( 0 )
w h ich are
c o n t a c t w i t h e a c h o t h e r may a c t
—— 2A
+
02
be s u r r o u n d e d b y a m asg o f m o l e c u l e s A
s tr o n g ly r ed u cin g a g e n ts:
B (0)
+
A —
B
+
A ( 0 ) — — AO ( s t a b l e )
The l i b e r a t e d B may t h e n r e a c t a g a i n i n t h e same way a n d a p o s i t i v e
c a ta ly sis re s u lts w ith th e
w i l l a c t as a p o s i t i v e
o x i d a t i o n o f A u n d e r i n f l u e n c e o f B.
o r n e g a t i v e c a t a l y s t d e p e n d in g upon w h e th e r
t h e p e r o x i d e B ( 0 ) p r e f e r s t o a c t o n A ( 0 ) o r u p o n Ae
A
+
B
Th uss
Og —s** AOg
A0S
+
B
+
A(0)
B ( 0 ) ------B ( 0 )
+
A( 0 ) —=— A + B +
negative c a ta ly s is
B (0)
+
A —
B
+
A (0 )
A ( 0 ) — •— AO ( s t a b l e )
positiv e cataly sis
B (0 ) may c h a n g e o v e r t o
oxidant i s
its
s t a b l e f o r m BO i n w h i c h c a s e t h e a n t i ­
lo st fo r c a ta ly sis.
w hile R e a c tio n I I i s
R e a c t i o n I i s f a v o r e d by v e l o c i t y
f a v o r e d by c o n c e n t r a t i o n .
o f t h e c a t a l y s i s may be a l t e r e d by v e r y s l i g h t
c o n d i t i o n s p l a y an important p a r t ,
ch aracteristics
of th e m edia,
Th us t h e d i r e c t i o n
changes.
such as t e m p e r a tu r e ,
Experim ental
lig h t effect,
a c t i o n o f t h e w a l l s o f t h e v e s s e l as
w e l l a s t h e i n d i v i d u a l n a t u r e o f t h e m o l e c u l e s A a n d B,
9
M i l a s r a i s e s f o ^ u m a i n o b j e c t i o n s t o M ou re u and D u f r a i s s e s
theory:
1.
The e n e r g y o f a c t i v a t i o n i n n o t a c c o u n t e d f o r .
A fter
t h e o r i g i n a l a c t i v a t e d m o l e c u l e s r e a c t and a r e r e t u r n e d t o t h e mix­
ture in a ctiv ate d ,
2.
no a c c o u n t i s made o f t h e e n e r g y o f a c t i v a t i o n ,
The i n h i b i t i o n a c c o u n t e d f o r i s p e r m a n e n t r a t h e r t h a n
te m p o ra ry a s e x p e r i m e n t a l work h a s shown,
3.
A ccording to t h e i r th e o r y , th e a d d itio n of organic
p e r o x i d e s s h o u l d c a u s e l i b e r a t i o n o f o x y g e n a n d I n h i b i t i o n du e t o
21
an tag o n istic d e stru c tio n
of th e peroxides already p re s e n t.
A ct­
u a l l y t h e o p p o s i t e r e s u l t s a r e o b t a i n e d and an a c c e l e r a t i o n i s
noted.
A l s o tw o p e r o x i d e s w i l l n o t r e a c t w i t h e a c h o t h e r u n l e s s
t h e o x i d a t i o n p o t e n t i a l o f on e i s much h i g h e r t h a n t h e o t h e r a n d
two s u c h p e r o x i d e s c o u l d n o t f o r m s i m u l t a n e o u s l y i n a g i v e n a u t o ­
oxidation.
4.
A ccording to C h r i s ti a n s e n
(1928)
some c h a i n m e c h a n ­
ism m u s t s u p p l e m e n t t h e i r t h e o r y i n o r d e r t o b e a r o u t h i s k i n e t i c
observations .
O t h e r i n v e s t i g a t o r s b e s i d e s M our eu a n d D u f r a i s s e
B&ckstrHiji e t c . )
have o b s e rv e d a r e l a t i o n s h i p betw een t h e
pov/er o f a n e g a t i v e c a t a l y s t
and i t s
o x id izab ility .
in h ib ito ry
H ow eve r n u m e r ­
ous c a s e s h a v e b e e n o b s e r v e d by M i l a s w h e r e d i f f i c u l t l y
s u b s t a n c e s e x e r t e d s. s t r o n g i n h i b i t o r y a c t i o n .
(Dhar,
oxidized
These e x c e p tio n s
may f o r m a d d i t i o n c o m p l e x e s w i t h t h e a n t i o x i d a n t a n d t h u s p r e v e n t
propagation of th e r e a c tio n c h a in .
M ilas examined v a r i o u s i n h i b i t o r s
and d i s c o v e r e d t h a t
a l l p o s s e s s e d m o l e c u l a r v a l e n c e e l e c t r o n s w hich were p r o b a b ly a t
d ifferen t p en etratio n s.
Thus,
an energy exchange b etw een th e
i n h i b i t o r and t h e d a t i v e p e r o x i d e r e s u l t i n g
ation^ o f t h e i n h i b i t o r ,
in the p a r t i a l a c tiv -
must o c c u r i n n e g a ti v e c a t a l y s i s *
e n e r g y e x c h a n g e t a k e s p l a c e w he n t h e i n h i b i t o r i s
or "synchron ous" r e l a t i o n w ith th e a u t o x i d a n t .
This
in a "resonance"
A ctivated in h ib ito r
m o l e c u l e s c a n t h e n be e i t h e r o x i d i z e d bv t r i e o r g a n i c p e r o x i d e s o r
by f r e e o x y g e n ,
o r c an combine w i t h t h e a c t i v e a u t o x i d a n t m ole­
cules to form u n s ta b l e
c o t n n l e x e s w h i c h on d e c o m p o s i t i o n y i e l d the.
o r ig in a l i n h i b i t o r m olecule.
22
A n o th e r mechanism o f n e g a t i v e
by R e i f f
(1926), B runner (1927), R id e al
c a t a l y s i s has been proposed
(1928)
and B a i l e y
(1930)
and i s b a s e d on t h e a s s u m p t i o n t h a t a u t o x i d a t i o n t a k e s p l a c e a t t h e
s u r f a c e o f t h e r e a c t i o n v e s s e l and i s
c a t a l y s t w hich i s
i n h i b i t e d by t h e n e g a t i v e
absorbed in high c o n c e n tr a tio n a t th e s u r f a c e .
This t h e o r y w ould seem t o a p p l y m o st a p p r o p r i a t e l y t o h e t e r o g e n e ­
ous n e g a t i v e
3.
cataly sis.
A u t o x i d a t i o n and in d u c ed o x i d a t i o n :
I n d u c e d o x i d a t i o n i s t h e p r o c e s s w h e r e b y an i n h i b i t o r
r e l a t i v e l y u n a f f e c t e d by o x y g e n w he n a l o n e ,
auto x id atio n re a c tio n .
A ll in h ib ito r s
l y o x i d i z e d a nd t h e c o n v e r s e o f t h i s
au to x id atio n re a c tio n s,
re a c tio n chains
is
been d e f i n i t e l y
established
occurs, w hether i t
o x i d i z e d d u r i n g an
are not n e c e s s a rily indueed-
i s known t o h o l d i n many c a s e s .
A c t u a l l y many i n d u e e d l y o x i d i z e d s u b s t a n c e s
to a c c e le ra te
is
are d e f in ite ly
known
a n d t h u s t h e p r o p a g a t i o n of
enhanced r a t h e r t h a n i n t e r r u p t e d .
I t has n ot
even i n o x i d a t i o n s i n w hich i n h i b i t i o n
i s th e induced o x id a tio n t h a t i n t e r r u p t s the
propagation of r e a c tio n c h a in s,
m olecules of th e a u to x id n n t.
or th e i n h i b i t o r w ith th e a c tiv e
Recent evidence p o in ts to th e l a t t e r
process.
4.
A u t o x i d a t i o n and p o l y m e r i z a t i o n :
C e rta in ty p es of u n s a tu ra te d organic
substances e x h ib it
a s t r o n g te n d e n c y t o undergo p o l y m e r i z a t i o n as w e ll as o x i d a t i o n .
Polym erization e x h ib its
c ataly sts
negative c a t a l y s i s
c a t - a l y - a t s a r e known t o
and c e r t a i n n e g a t i v e
i n h i b i t p o ly m e riz a tio n as w e ll
as a u t o x i d a t i o n .
O ther n e g a tiv e c a t a l y s t s w i l l i n h i b i t polym er­
i z a t i o n but allov; a u t o x i d a t i o n t o p ro c e ed a t a r e l a t i v e l y
M ilas
(1930)
high r a t e
and o t h e r s have a s s o c i a t e d a c h a i n mechanism
w ith t h i s ty p e of p o ly m e r iz a tio n .
In a c c e le ra te d polym erization,
t h e o r g a n ic p e r o x i d e s seem t o b ehave as " t r i g g e r " c a t a l y s t s ,
in it­
i a t i n g r e a c t i o n c h a i n s by r e a c t i n g d i r e c t l y w i t h t h e a u t o x i d i z a b l e
substances.
W ith oxygen, p o l y m e r i z a t i o n i s u n d o u b te d ly e f f e c t e d
by t h e e n e r g y l i b e r a t e d
d u rin g th e fo rm atio n of th e d a tiv e perox­
i d e s , t h e i r s u b s e q u e n t r e a r r a n g e m e n t a nd d e c o m p o s i t i o n o f t h e r e ­
arranged p ro d u c t, t h e i r p o ly m e riz a tio n ,
or t h e i r r e a c tio n w ith
the a c tiv e u n o x id iz e d m o lecu les of th e a u to x i d a n t s .
When p o l y m e r i z a t i o n a n d a u t o x i d a t i o n o c c u r s i m u l t a n e o u s ­
l y , t h r e e p o s s i b l e r e a c t i o n s may t a k e p l a c e :
the u n satu rate d s u b sta n c e ,
izatio n .
peroxides.
(b)
(a) A u to x id atio n of
an i n d is p e n s a b le r e a c t i o n t o polym er­
P o ly m e riz a tio n of or through th e a id of th e d a tiv e
(c) D ire c t p o ly m e riz a tio n of th e a c tiv e u n sa tu rate d
m olecules.
5.
A u t o x i d a t i o n and S t r u c t u r e :
The s u s c e p t i b i l i t y
a c ti o n of m o le c u la r oxygen i s
of an a u to x id iz a b le
dependent upon i t s
substance to the
stru ctu re.
It
ha s b e e n p r o v e d q u a l i t a t i v e l y t h a t d i f f e r e n t
g roups i n a m olecule
behave d i f f e r e n t l y to w a rd m o l e c u l a r oxygen.
In th e a u to x id a tio n
of u n s a tu r a te d
s u b s t a n c e s , t h e p o s i t i o n o f t h e d o u b l e b o n d seems
t o b e more i m p o r t a n t t h a n t h e i n f l u e n c e e x e r t e d by d i f f e r e n t g r o u p s
A d o u b l e bo nd a t t h e e n d o f t h e compound i s
i n t e r n a l double bond.
less
r e a c t i v e th a n an
24
C la s s ific a tio n of A utoxidation R eactions:
M ilas c l a s s i f i e s
I#
a u t o x i d a t i o n r e a c t i o n s i n t o two c l a s s e s -
R eversible R eactions:
i n w hich t h e
This c la s s in c lu d e s a u to x id a tio n s
o x y g e n a d d i t i o n c o m p o u n d s o f t h e a u t o x i d a n t show c o n ­
s id e r a b le d i s s o c i a t i o n a t low er p r e s s u r e s or h ig h e r te m p e ra tu re s
t h a n t h o s e u n d e r which t h e y a r e f o r m e d .
This c l a s s in c lu d e s such
t y p i c a l examples a s , t h e a u t o x i d a t i o n o f hem oglo bin, hem ocyanin, e t c .
II.
I r r e v e r s ib le R eactions:
i n which t h e
This c la s s
in cludes autox id atio n s
oxygen form s w i t h t h e a u t o x i d a n t s n o n - d i s s o c i a b l e b u t
o f t e n h i g h l y u n s t a b l e p e r o x i d e s w h i c h may r e a r r a n g e o r d e c o m p o s e
s p o n ta n e o u s ly t o form s i m p l e r p r o d u c t s .
This c l a s 3 in c lu d e s th e
follow ing a u to x id a tio n s :
S a tu ra te d hydrocarbons:
a dd d i r e c t l y t o
M o lec u la r oxygen w i l l not
s a t u r a t e d h y d ro c a rb o n s t o form p e ro x id e s because
t h e h y d r o c a r b o n le.cks m o l e c u l a r v a l e n c e e l e c t r o n s .
E xperim ental
work i n d i c a t e s t h a t t h e C-C bo nd r a t h e r t h a n t h e C-H bond i n t h e
hydrocarbon i s broken in th e d e co m p o sitio n .
from a s t u d y o f t h e h e a t s
T h i s may be e x p e c t e d
of d i s s o c i a t i o n of th e s e bonds.
An
a c t i v a t i o n o f t h e s o b o n d s d u r i n g o x i d a t i o n may b e s u f f i c i e n t t o
expose th e n e c e s s a r y e l e c t r o n s t o th e
com bining a c t i o n of oxygen.
U nsaturated hydrocarbons:
c lass are the
oxidation of acetylene
T y p ic a l examples of t h i s
and e t h y l e n e .
Both t h e s e
o x i d a t i o n s a r e o f t h e c h a i n ty p e and e x h i b i t an i n d u c t i o n p e r i o d .
An u n s t a b l e p e r o x i d e
i s fo rm ed and e v e n t u a l l y u n s t a b l e h y d r o x y l a t o d
substances r e s u l t .
D rying O ils :
The i n i t i a l
stage in th e
autoxidation
25
of d ry in g o i l s
i s t h e f o r m a tio n o f o r g a n ic p e r o x id e s p ro b a b ly of
th e m oloxide t y p e .
I n t h e p r o d u c t io n of s t a b l e f i l m s th e m oloxide
a p p a r e n t l y r e a c t s w i t h t h e u n o x id iz e d o i l t o form monoxides w hich
polym erize.
The f o r m a t i o n o f p e r - a c i d s n a y b e a c c o u n t e d f o r by
t h e d i r e c t o x i d a t i o n o f a l d e h y d e s f o r m e d by d e c o m p o s i t i o n o f t h e
m oloxides.
I n t e r a c t i o n of th e per-e.cids w ith unoxid ized o i l y ie ld s
s m a l l a m o u n t s o f r a o n o x i d .e s .
A theory
s u g g e s t e d by E l l i s
(1926)
in c lu d e s the re a rra n g e ­
ment o f t h e m o l o x i d e i n t o k e t o - h y d r o x y comp oun d:
I
I-I-C-0
1 i
H-C-G
I
FI—C
0o
/(
I I —G
G—011
II
II-C -O H
■0
C-OII
I n s p i t e o f n i l t h e v/ork d o n e on u n s a t u r a t e d o i l s ,
during a u to x i d a t i o n i s
still
t h e i r mechanism
u n c e r t a i n duo c h i e f l y t o t h e c o m p l e x ­
ity of th o o x id a tio n p r o d u c ts .
A ldehydes;
autoxidation
of ald eh y d es:
Two t h e o r i e s
h a v e boo n o f f e r e d f o r t h e
The f i r s t t h e o r y p o s t u l a t e s t h e f o r m a ­
t i o n o f a n i n t e r m e d i a t e p e r o x i d e c o n s i s t i n g ox a m o l e c u l e o f oxygo n
a dd ed t o t h e
per-acid
is
carbonyl bond.
The. s e c o n d t h e o r y s u g g e s t s t h a t t h e
a prim ary p ro d u ct of th e
o x id a tio n of th e aldehyde.
The m e c h a n i s m o f a u t o x i d a t i o n o f a l d e h y d e s h a s b e e n shown t o bo o f
tho c h a i n t y p e i n b o t h t h e l i q u i d and v a p o r p h a s e .
E th ers:
boon i n t e r n r e t e d
Tho a u t o x i d a t i o n mo c h a n i s m o f e t h e r s h a s
on t h e b r s i s
o f t h o o x on ii un p e r o x i d e t h e o r y w h i c h
a ss u m e s t h a t t h o o x y g e n n o 1 e c u l e s .adds o n t o t h e e t h e r o x y g e n .
II e a r r a n g one n t a n d d e c o m n o s i t i o n o f t h e d a t i v e
ooroxide follow s
26
w i t h t h e f o r m a t i o n o f a l d e h y d e s and a l c o h o l s .
P e r - a c i d s and p e r -
e s t e r s a r e p o s s i b l y f o r m e d on f u r t h e r _o x i d a t i o n o f t h e a l d e h y d e s .
»
Coe
s P h o to ch em ical Theory of R a n c id ity :
This th e o ry
{Coe ( 1 9 3 8 ) )
of o x id a tio n o f v e g e ta b le
oils
vms c o n c e i v e d a f t e r a l e n g t h y p h o t o c h o m i c a l s t u d y o f r a n c i d i t y .
R ancidity is
c o r r e l a t e d w i t h t h e p r e s e n c e o f c h l o r o p h y l l and a
disrupted p h o to sy n th esis.
A su bstance c a lle d p r o to c h lo ro p h y ll, the
p r e c u r s o r of c h l o r o p h y l l ,
i s p r e s e n t i n th e seed w hich i s p r o te c te d
f r o m l i g h t by t h e s e e d c o a t i n g .
ophyll i s
converted in to
c h l o r o p h y l l by t h e a c t i o n o f t h e s u n l i g h t .
T h i s a l s o o c c u r s when t h e o i l i s
th e p ro to c h lo ro p h y ll —
D uring g re m in a tio n th e p r o t o c h l o r ­
e x p re s s e d from t h e
c h l o r o p h y l l by s u n l i g h t ) .
p h y ll is then p re s e n t as v e ry sm all p a r t i c l e s
p articles
a c t as p h o t o s e n s i t i s e r s .
disappear.
'Then t h e
been e x p r e s s e d from t h e
le ft
accum ulate i n th e
ab­
a b s o r p t i o n bands
form i n t h e o i l .
I f t h e o i l has
b e h i n d a nd t h e
o i l w h i c h be co m e s
H e r e Hoe p o s t u l a t e s t h e p r e s e n c e o f a n a c t i v e f o r m o f h y d r o ­
gen p e r o x i d e ,
place
in the p la n t.
seed t h e cata.la.se i s
p e ro x id e s arc th e n p e r m itte d to
rancid.
ch aracteristic
D u r i n g m e t a b o l i s m p e r o x i d e s a r e known t o
catalase
o i l a nd t h e s e
The p r e s e n c e o f t h e c h l o r o p h y l l
o i l becomes r a n c i d t h e s e
T h e s e a r e d e s t r o y e d by t h o
(d. e , ,
The c h l o r o ­
in the
i n t h e o i l may b e shown s p e c t r o s c o p i c a l l y by i t s
s o r p tio n band.
need,
HO.OH w h i c h he s t a t e s
is the a c tiv e
o x i d a n t in. t h o
of m o lecu lar oxygen.
F inely
d iv id e d m e ta ls as i r o n ,
brhen i n c o n t a c t w i t h t h e
ic pero x id es
o il
copper,
nick el,
zinc,
a lso produce hydrogen p e ro x id e .
e tc.,
Lrgen-
a p p a r e n t l y h a v e no e f f e c t u n l e s s they a r e h y d r o l y z e d
27
i n t h e p r e s e n c e o f m o i s t u r e t o HO.OH.
The i n d u c t i o n p e r i o d i n n o r m a l f u n c t i o n i n g o f p h o t o s y n ­
t h e s i s may b e l o o k e d u p o n a s t h e t i m e i t t a k e s t h e l i g h t t o b e a b ­
s o r b e d by t h e c h l o r o p h y l l o r t h e t i m e f o r t h e f o l l o w i n g r e a c t i o n
to take p la c e :
Hydrogenated c h lo r o p h y ll +
hv
M onodehydrochloro-
( l i g h t energy)
Then
H
+
HOg
p hyll +
H
Og —5- HOg
+
HOg — =- HgOg
+
^2
The c a t a l a s e p r o d u c e d by t h e p l a n t m a t e r i a l d e s t r o y s t h e h y d r o g e n
peroxide.
2Hg0g
+ catalase —
When t h e o i l i s
is also expressed
(i. e .,
+
Og
e x p re ssed , p a r t of the p h o to s e n s itiz e r
protochlorophyll)
lig h t i s converted in to c h lo ro p h y ll.
then ta k es p la ce
2H2 0
(ind uction period)
and on e x p o s u r e t o
Fhotochem ical a b s o r p tio n
in th e presence of d is r u p te d
p h o t o s y n t h e s i s m e c h a n i s m a n d t h e l o o s e l y c o m bin e d h y d r o g e n f r o m
chlorophyll is lib e r a te d
and u n i t e s w i t h m o le c u la r oxygen as
follow s:
I-IOg
S in c e t h e r e
is
+
HOg —*• HO. OH +
no c a t a l a s e p r e s e n t i n t h e e x p r e s s e d
l o o s e l y c o m b in e d h y d r o x y l s
w h ich g i v e r i s e
02
o il,
th e
u n ite w ith u n sa tu ra ted g ly c e r id e s
t o th e r a n cid
com pounds.
Th us c h l o r o p h y l l t r a n s f e r s
its
a c ti v a tio n through f r e e
h y d r o g e n t o m o l e c u l a r o x y g e n a s t h e l o o s e l y c o m b in e d HO.OH a nd
is able to r e a c t w ith th e u n s a tu ra te d g ly c e r id e s .
23
The n u m b e r o f - a c t i v a t e d c h l o r o p h y l l m o l e c u l e s t a k i n g
place in th e r e a c t i o n i s
d e t e r m i n e d -by t h e c o n c e n t r a t i o n o f c h l o r o 5
phyll.
A c c o r d i n g t o B e e r s l a w , t h e more s e n s i t i z e r , t h e f a s t e r
j
t h e r e a c t i o n b u t L a m b e r t s lav/ a l s o f u n c t i o n s a n d t h e o i l l a y e r
nearest the
rad iatio n
R efined,
source re c e iv e s tho g r e a te s t a b so rp tio n .
b l e n c h e d a n d d e o d o r i z e d o i l s become r a n c i d
f a s t e r t h a n c r u d e and e v e n u n b l e a c h e d r e f i n e d o i l s .
A p ossible
e x p l a n a t i o n f o r t h i s may be t h a t t h e y e 11 or/ o r brov/n c o l o r i n g
d
pin en ts arc
so r e d u c e d t h a t t h o a c t i n i c
g r e a t e r d e p t h and t h u s
o x ciiirr’
m olecules.
in r a n c i d i t y
Tho r e s u l t
p.
lig h t p e n e tra te s to a
g r e a t e r numb er o f c h l o r o p h y l l
in a s h o r te r tim e.
I t ".'as . s u g g e s t o r by B n f . f r o n ( 1 1 2 6 )
th a t the
sen sitizer
ney a c t a s a n o x y g e n t r a n s p o r t e r t o t h e a c c e p t o r v/hich i n t h i s
i s t h e un s a t u r a t e d g l y c e r i d e .
s home d t h a t p e r ox id ex:
c h l o r o p h y l l s o l u t i o n i n ir.oa:~*l amino ■■r a
a c r e f o r m e d v/hcn t h e
irrad iated .
” o (1127)
cane
The q u a n t i t y
o f p e r o x i d e s ’; , i - m g hg !r o on pm-oxja'a mnd
o r g a n i c g o r c x i d c s , found.
s rr.irs t i n e s
the; e-nnuei e o u i v r l o n l J: o
t h o rsnoimt o f c h l c r n p h y l ’1 p e r c e n t w h i c h n e i i l d nca.r t h a . t oaf.;: ■' c m 1j
amount o f c h l o r o r h y l f
is
necossrrp
’.'h i s a p p a r e n t l y
v.ns
ity
of r o l v . r '
in
The e a r n
peroxide.-
the
n o r m nC. Cm a : : ! t-v;o i n a c t i v e ,
^
e
j
e
f o i arm by t a n
a
3 ~
>■-
+
r
a ’d i t i o n
■■ y
-
i
of
-■r.
b r a n g '. b e n t t h e r n a c a i o n .
ce.ne ' n i t h f ' c
m l
f o r m e d v h r' v' :a; c ’ l
tc
-’ c o f . o i - i z c d
1
exposed
' gOv.
(
i
- i e x
and
\
•.
hv-roaon. t o
to
level mmab
of
r a r . c m ’-
oils.
sunlight,
organic
an a c t i v e
peroxides.
r *’0 --
- a a
-
: , o l ■. c i f a na ox." ■■'■ea.i.
- i„.
T he
as f o l l o w s :
H : 0 : 0 : H
(active)
The OH g r o u p s a r e l o o s e l y c o m b i n e d a s t h e p e r o x i d e i s f o r m e d , a n d
because of t h e i r a f f i n i t y
f o r th e u n s a tu ra te d bond, they sep a ra te
and u n i t e w i t h t h e g l y c e r i d e t o p r o d u c e t h e r a n c i d compound.
A ll
tho hydrogen p e ro x id e i s n o t n e c e s s a ry i n t h a t a c t i v e form because
under exposure to l i g h t i t
H
is
d e c o m p o s e d t o HgO a nd 0 2 a s f o l l o w s :
:
»1
0 :
( t
IS-
,i
H
0 :
+ hv —
1I2 0
*
'
o2
(in activ e)
This i n a c t i v e s t a t e w i l l not produce r a n c i d i t y i n o i l s .
\
+
Organic
'
peroxides
H : 0 : 0 : R a r e a l s o i n a c t i v e b u t may b e h y d r o l y z e d
»v
*s
to th e a c ti v e hydrogen p e ro x id e form .
HO.OR
+
HOH —a» HO.OH ( a c t i v e )
Emery a n d H e n l e y ( 1 9 2 2 )
+
ROH
found t h a t an o i l exposed to
l i g h t i n t h e a b s e n c e o f m e t a l s becomes r a n c i d i n t h e
same t i m e a s
an o i l i n c o n ta c t w i t h m e ta ls in th e absence o f l i g h t .
K u f f e r a t h and M erckens
(1904)
g r a p h ic im ages w i t h m agnesium , aluminum,
(1905)
obtained photo­
zinc,
c ad m iu m , n i c k e l ,
c o b a l t a n d l e a d when t h e s e m e t a l s w e r e p l a c e d i n c o n t a c t v / i t h
photographic p l a t e s .
The e x p l a n a t i o n o f f e r e d b y t h e m was t h a t
t h e m e t a l was o x i d i z e d a n d t h e h y d r o g e n p e r o x i d e p r o d u c e d s c t e d
on t h e p l a t e .
The m e t a l i t s e l f
is
i n a c t i v e b u t w ith m oisture
a nd o x y g e n , h y d r o g e n p e r o x i d e i s p r o d u c e d .
ha ve m ore o r l e s s
O ther in v e s t i g a t o r s
s u b sta n tia te d th ese r e s u lts
and from t h e s e
Coe s u g g e s t s t h a t r a n c i d i t y i n o i l s w i t h m e t a l s i s d u e t o t h e same
mechanism a s w i t h l i g h t .
In th e
c a s e o f s u n l i g h t t h e m echanism i s
due t o p h o t o c h e m i c a l a c t i o n i n d u c e d by c h l o r o p h y l l a s t h e p h o t o sen sitizer*
of m e ta ls .
In the
o t h e r c a s e t h e m echanism i s
The e n d - p r o d u c t s i n e a c h c a s e a r e t h e s a m e .
In th e case of anim al f a t s ,
(b u tter),
first,
du e t o t h e a c t i o n
ran cid ity
f o r exam ple, a churned f a t
develops th ro u g h th e photochem ical a c t i o n due,
to t h e p re s e n c e of n a t u r a l pigm ents c lo s e ly r e l a t e d to
c h lo ro p h y ll w hich a c t as th e p h o t o s e n s i t i z e r s ,
action of m etals.
and se c o n d ,
to the
I n e i t h e r c a s e t h e e n d - p r o d u c t s a r e t h e darae.
In th e case of a f a t l i k e
lard ,
r a n c i d i t y d e v e l o p s due
to th e p r e s e n c e of hem oglobin w hich a c t s as a p h o t o s e n s i t i z e r or
to th e iro n p re s e n t in th e reduced s t a t e
oxygen i s
i n hem oglobin.
occluded d u rin g s o l i d i f i c a t i o n in a f a t lik e
Much
l a r d and
t h i s may a s s i s t l i g h t i n r a n c i d i f i c a t i o n a n d t h u s r a n c i d i t y
is
produced f a s t e r i n th e s e f a t s t h a n i n v e g e ta b le o i l s .
»
Coe s e x p e r i m e n t a l w o r k :
From p r e v i o u s w ork i t
had b e e n fo u n d t h a t g r e e n f i l t e r s
( t r a n s m i s s i o n b e t w e e n 4 9 0 0 a n d 58 00 A n g st rB m u n i t s )
ity .
This su g g este d th e p o s s i b i l i t y
delayed r a n c id ­
t h a t green p l a n t pigm ents in
o i l s a c t i n g as p h o t o s e n s i t i z e r s were r e s p o n s i b l e f o r r a n c i d i t y
when t h e
o i l was e x p o s e ! t o
lig h t.
o r when g r e e n f i l t e r s w e r e u s e d ,
V/hen a l l l i g h t was e x c l u d e d
the green p h o to s e n s itiz e r s ceased
to fu n c tio n .
M a g n e s i u m c h l o r o p h y l l was a d d e d t o v e g e t a b l e
ran cid ity
oils
and
d e v e l o p e d q u i c k l y y e t y i e l d e d a low p e r o x i d e n u m b e r .
No c o r r e l a t i o n w as a p p a r e n t .
Copper s t r i p s w ere p la c e d i n th e f a t
sam ples.
( c o r n o i l and l a r d )
R a n c i d i t y d e v elo p e d w ith t h e p r o d u c tio n o f hydrogen p e r ­
oxide a s i n d i c a t e d by t h e y e llo w c o l o r o b ta in e d w ith t i t a n i u m s u l ­
fate.
When t h e c o r n o i l
filter,
(no c o p p e r s t r i p )
was p r o t e c t e d by a g r e e n
no h y d r o g e n p e r o x i d e w as f o r m e d a l t h o u g h o r g a n i c p e r o x i d e s
were p r e s e n t .
Corn o i l
(peroxide f r e e )
ir r a d ia te d w ith u l t r a - v i o l e t
became r a n c i d a nd h y d r o g e n p e r o x i d e w as f o r m e d a s i n d i c a t e d by t h e
yellow c o lo r of ti ta n iu m
su lfate.
A n o t h e r g r o u p o f e x p e r i m e n t s w e r e c a r r i e d o u t by means
o f th e R u s s e l l e f f e c t w hich is
a method o f d e t e r m i n i n g t h e p r e s e n c e
o f h y d r o g e n p e r o x i d e by m e a n s o f p h o t o g r a p h i c p l a t e s .
placed over ( l )
ter,
(4)
a rancid o i l,
(2)
P l a t e s were
a nd o i l p r o t e c t e d by a g r e e n f i l ­
( 3 ) a f r e s h o i l w h i c h h a d b e e n k e p t i n a r e f r i g e r a t o r and
a sample of b en zo y l p e r o x id e .
O nl y i n t h e c a s e o f t h e r a n c i d
o i l was a f o g g i n g o f t h e p h o t o g r a p h i c p l a t e o b t a i n e d , t h u s i n d i c a t ­
ing the p re se n c e of hydrogen p e ro x id e ,
w i t h benzoy/l p e r o x i d e i t
do n o t c a u s e f o g g i n g .
Q i h c e .no im a g e was o b t a i n e d
may b e c o n c l u d e d t h a t o r g s . n i c p e r o x i d e s
I f a n o i l h a s a, h i g h p e r o x i d e number b u t
g i v e s no R u s s e l l e f f e c t ,
organic p ero x id es are p re s e n t.
I f hydrogen p e ro x id e i s added to
of ra n c id ity
not in th e
an o i l ,
no a c c e l e r a t i o n
i s produced i n d i c a t i n g t h a t th e hydrogen peroxide is
a c ti v e form.
are not of th e r e a c tiv e
P eroxides
type.
o x i d e s a s t h e y g i v e no R u s s e l l
If active
developed under a green f i l t e r
The;/ m u s t b e l a r g e l y o r g a n i c p e r ­
effect.
c a ta la s e i s p re s e n t in the
o il,
no r a n c i d i t y
w i l l develop as th e a c t i v e hydrogen p e ro x id e i s
t h e c a t a l a s e becomes i n a c t i v e ,
e f f e c t of c a ta la s e i s
o x i d a n t s and i t
ran cid ity re s u lts .
b u t when
The i n h i b i t i n g
e q u i v a l e n t t o t h a t o f t h e w e l l known a n t i ­
i s m o re e f f i c i e n t t h a n any o f t h e common a n t i o x i d ­
ants except p y ro g a llo l.
o ils.
destroyed,
ho c a t a l a s e h a s b e e n f o u n d i n t h e
The p r e s s c a k e c o n t a i n s
larg e
expressed
amounts of c a t a l a s e .
9
D i s c u s s i o n a nd c o n c l u s i o n s o f Coe s w o r k :
C ertain f i l t e r s
p r o t e c t can o i l o r f a t a g a i n s t r a n c i d i t y
t o a g r e a t e r e x t e n t them o t h e r f i l t e r s .
presence of p h o t o s e n s i t i z e r s
u ltra-v io let,
so n sitizers
v io let,
blue,
This i s
e x p l a i n e d by t h e
i n t h e o i l which a b s o r b l i g h t
o r a n g e a nd r e d r e g i o n s .
in tho
These p h o to -
c o n t r i b u t e t o th e developm ent of r a n c i d i t y
but t h e i r
a c t i o n may be r e t a r d e d by t h e p r e s e n c e o f s e x t a n t g r e e n f i l t e r s .
That th e p h o t o s e n s i t i z e r s
a re r e s p o n s i b l e f o r t h e developm ent of
r a n c i d i t y wan p r o v e n by a d d i n g m a g n e s i u m c h l o r o p h y l l t o t h o o i l .
The r e s u l t w as a r a p i d d e v e l o p m e n t o f r a n c i d i t y w i t h a. low p e r ­
oxide v a l u e .
ho e x p l a n a t i o n was o f f e r e d f o r t h e lo w p e r o x i d e
value.
The e x p e r i m e n t s w i t h t i t a n i u m s u l f a t e a n d t h e R u s s o i l
e ffe c t in d ic a te d the presence
became r a n c i d .
o f h y d r o g e n p e r o x i d e •'.-hen an o i l
O r g a n i c p e r o x i d e s may be p r o d u c e d a n d t h o . o i l
w i l l show no s i g n s o f r a n c i d i t y ;
h y d r o g e n p e r o x i d e may be a d d e d
t o t h e o i l w i t h no p r o d u c t i o n o f r a n c i d i t y ,
T h is would i n d i c a t e
t ’: a t t h e h y d r o g e n p e r o x i d e m u s t bo i n t h e a c t i v e 5!G. O’i f o r m t o
produce r a n c i d i t y .
th at
ran cid ity is
A ll exporim ants seen to
s u p p o rt tho th e o r y
i n d u c e d by 1 i b e r a t e d h y d r o g e n u n i t i n g w i t h
33
m olecular
oxygen t o form b o t h l o o s e l y combined hydrogen p e r o x i d e
and s t a b l e h y d r o g e n p e r o x i d e .
The a c t i v e f o r m a t t a c h e s
i t s e l f to
t h e u n s a t u r a t o d bond o f t h e g l y c e r i d e g i v i n g r i s e t o t h e f o r m a t i o n
of t h e r a n c i d compounds.
F r e e h y d r o g e n may b e p r o d u c e d i n two
w a y s : - e i t h e r by p h o t o c h e m i c a l a c t i o n o f l i g h t ,
of c e r t a i n m e ta ls .
o r by t h e p r e s e n c e
I n e a c h c a s e t h e mechanism o f r a n c i d i f i c a t i o n
i s t h e same.
The f o l l o w i n g e q u a t i o n s may b e t t e r i l l u s t r a t e
the r e a c t ­
ions ta k in g p la c e :
(1)
P rotochlorophyll
(3 )
C hlorophyll
+
+
S u n l i g h t — »— C h l o r o p h y l l
Sunlight
+
0 2 — *— n a s c e n t h y d r o g e n
+
M oiiohydrogenated c h l o r o p h y l l
(3 )
(4 )
Mas c e n t H y d r o g e n
-CH
=
CH-
+ On
+
+2II0.0H —
S unlight —
- CH - CH0
(5)
-CII - CH- — >■ 2RCH0
I
I
- 0
+
HO. Oil
+
H
2II2 0
g ly c e rid e peroxide
%
r a n c i d compound
0 - 0
P ossible
actio n :
(6 )
02
+
S u n l i g h t —s— 0 3 o z o n e
(7)
-CH = CH-
+
0., —
- CH - CH
l
i
0
-
2RCH0
+ H2 0g
0-0
T h i s r e a c t i o n d o e s riot scorn t o be t h e u s u a l s t e p i n t h o d e v e l o p ­
ment of r a n c i d i t y .
R eactions in th e presence
(8 )
-CH = CH:
+
o f r.n a n t i o x i d a n t :
2H0.0H
+ c a t a l a s e -— >- PHgC + (Js +
( a n t i cxid a n t )
34
Ho r a n c i d compound f o r m s a s l o n g a s t h e c a t a l a s e
A ction of th e a n t i o x i d a n t s
(9)
-CH = CH-
as s t a b i l i z e r s :
+
+
MO.OH -------
hydroquinone
(ft) +
(10)
HH2 0 + -CH = CH-
quinone
I f r a n c id ity s t a r t s b e fo re th e a n tio x id a n t i s
the r e a c tio n i s
is present.
added,
no c h e c k i n
afforded:
-CH - CHI
I
0 ------ 0
+ f j
+
OH
HO.Oil —
fO
V
+
2RCHO
+ 2IU0
H o t a l M e c h a n is m :
(11)
-CH = CH-
+ M etal + 02
+ 2HS0
► -CH = CH+
(12)
-CH = CH-
+ I'eOH
+ 2H
+
+ CH
+
02
M etal hydroxide
02 — > -CH = OH- +
HO. OH
+
I..'oOI I
(13)
-CH = CH-
+ 2 HO. OH
+
Me OH — »* 2RC1I0 +
A nor' m e a n i n g o f " i n d u c t i o n p e r i o d "
boon b e l i e v e d t h a t
is
Me OH
offered.
+
2H2 0
I t ha s
c e r t a i n n a t u r a l a n t i o x i d a n t s a r e p r e s e n t v/hich
delay the developm ent of r a n c i d i t y .
the in d u ctio n p e rio d i s
the
T his nov t h e o r y in d ic a to r, t h a t
tim e f o r th e p h o t o s e n s i t i z e r o r tho
m etal c a t a l y s t to g e n e r a te th e r e a c t i v e
t h e y r e a c t and p r o d u c e o r g a n o l e p t i c
s u b s t a n c e s t o & p o i n t v/hero
ran cid ity .
35
HISTORICAL
II
Experim ental - R an c id ity
F a t d e t e r i o r a t i o n h a s b e e n a s u b j e c t o f w ide s p r e a d
i n t e r e s t and e x p e r i m e n t a t i o n .
The e a r l y l i t e r a t u r e
contains a
c o n f u s i n g m a s s o f d a t a much o f v / h i c h a p p e a r s t o b e c o n t r a d i c t o r y .
This s t a t e
that
is,
is
due c h i e f l y
the fre s h f a t s
-to t h e c o m p l e x i t y o f t h e . m a t e r i a l s ,
and o i l s ,
t h e i r r a n c i d p r o d u c t s and t h e
c o n d i t i o n s u n d e r v/hich t h e e x p e r i m e n t s a r e c a r r i e d o u t .
C onfusion i s
" r a n c i d i t y ’’.
e n c o u n t e r e d e v e n when d e f i n i n g t h e t e r m
The o r i g i n o f t h e t e r m " r a n c i d "
i s t h e Germanized
L a tin " r a n c id u s " meaning sh arp o r s c r a p i n g ( R i t s e r t
E a r ly c r i t e r i a f o r r a n c i d i t y w ere o d o r and t a s t e ,
b a s is f o r com parison i s
tests
give i n d e f i n i t e
n itio n ,
b u t a s no
a v a ila b le w ith organoleptic
resu lts
and a re
(1890)).
tests,
these
su b ject to p e rso n al reco g ­
The p r e s e n c e o f f o r e i g n m a t e r i a l s may mask t h e s e t e s t s .
I n 1795 S c h e r e r a t t e m p t e d t o
d e s c r i b e r a n c i d i t y s.s a c h e m i c a l p r o -
cono*
D i f f e r e n t t y p e s o f r a n c i d i t y w e r e r e c o g n i z e d a nd a
;D
c l a s s i f i c a . t i o n was s u g g e s t e d by T r i e b o l d
his c l a s s i f i c a t i o n th e th re e
ativ e,
h y d r o l y t i c and k e t o n i c
through d i f f e r e n t c a u s e s,
(1931).
A ccording to
ty p e s of f a t d e t e r i o r a t i o n a re oxid­
ran cid ity .
These a r e i n i t i a t e d
p r o c e e d t h r o u g h d i f f e r e n t mechanism s,
y i e l d d i f f e r e n t e n d - p r o d u c t s a nd a r e p r e v e n t e d by d i f f e r e n t me an s .
O xidative r a n c id ity
i n c l u d e s t h a t t y p e v /h ic h i s
c a u s e d by t h e
a d d i t i o n of m o l e c u la r oxygen t o u n s a t u r a t e d g l y c e r i d o s w i t h th e
form ation of pero x id es
aldehydes, keto n es,
o r s i m i l a r co mp ounds v / h i c h d e c o m p o s e i n t o
acid s,
etc.
H y d ro ly tic r a n c i d i t y d e a ls w ith
th e h y d ro ly s is o f g l y c e r i d e s w ith th e subsequent l i b e r a t i o n of
free
fa tty acid s.
K e t o n i c r a n c i d i t y i s o b t a i n e d by t h e a c t i o n
o f m o l d s on f a t s w i t h t h e p r o d u c t i o n o f k e t o n i c p r o d u c t s .
th is
f i r s t type
sidered
Only
of r a n c i d i t y ,
o x i d a t i v e r a n c i d i t y , w i l l be c o n ­
O xidative r a n c id ity
a p p e a r s t o be a s p o n t a n e o u s o x i d ­
.
a t i o n r e a c t i o n w hich ta k e s p l a c e only i n t h e p re se n c e of oxygen.
S c h e r e r i n 1795 s t a t e d t h a t f a t s
on l o n g s t a n d i n g a b s o r b o x y g e n
f r o m t h e a i r a n d become r e . n c i d a s d e t e r m i n e d by t h e s h a r p b i t in g ^ts.ste.
Sp&th (1 8 9 6 ) s t a t e d
t h a t r a n c i d i t y was an o x i d a t i o n
p r o c e s s where t h e u n s a t u r a t e d f a t t y
a t t a c k e d by a t m o s p h e r i c
a c i d s were p r i n c i p a l l y
oxygen t h r o u g h a c t i o n of l i g h t w i t h th e
fo r m a tio n of a c id s of low er c arb o n c o n te n t .
I n 1904 t h e mechan­
i s m o f o x i d a t i o n was s u g g e s t e d by E n g l e r a n d W e i s s b e r g t h a t m o l e ­
c u l a r oxygen a t t a c k s t h e u n s a t u r a t e d bonds i n t h e f a t t y
acids w ith
t h e s u b s e q u e n t f o r m a t i o n o f an u n i s o l a t e d p e r o x i d e t o w h ic h t h e
t e r m " m o l o x i d e " was g i v e n ( P o w i c k
(1923)).
I t may t h u s b e s e e n t h a t a l l t h e o r i e s a g r e e t h a t m o l e ­
c u l a r oxygen a t t a c k s t h e u n s a t u r a t e d g l y c e r i d e y^gilding a p e r o x id e
o r oxide.
This lo o s e ly
oses spontaneously in to
combined ( l a b i l e )
o x y g e n compound deco mp­
lo w e r m o l e c u l a r w e i g h t compounds.
Decomp­
o s i t i o n o f t h e g l y c e r i d e n o t o r d i n a r i l y a t t a c k e d by m o l e c u l a r o x y ­
g e n may t a k e p l a c e w i t h t h e
l i b e r a t i o n o f a c t i v e o x y g e n o r oz-one
(Powick (1 9 2 3 ) , K e r r and S o r b e r ( 1 9 2 3 ) ) ,
e i t h e r the fr e e u n sa tu ra te d f a t t y
O xidation occurs w ith
acid or i t s
glyceride.
I t majr be w e l l t o m e n t i o n h e r e t h a t o x i d a t i o n r e a c t i o n s
o c c u r i n a t l e a s t tw o s t a g e s :
o x id a tio n p o t e n t i a l and (2)
bank a n d D e y s h e r ( 1 9 2 7 ) ) .
(l)
i n b u i l d i n g u p co mp ou nds o f h i g h
in actu al oxidation its e I f
( Holm, G r e e n -
The f o r m a t i o n o f m o l o x i d e s c h a n g e s t h e
oxidation p o te n tia l of th e u n satu rate d
in oxidation p o te n tia l of f a ts
compounds.
This v a r i a t i o n
a n d o i l s may b e d e t e c t e d by t h e a c t ­
io n upon o x i d n t i o n - r e d u c t i o n i n d i c a t o r s .
Factors In flu e n c in g O xidation:
The s e c o n d a r y f a c t o r s
aid in g th e p ro d u c tio n of o x id ativ e
r a n c i d i t y h a v e c a u s e d c o n s i d e r a b l e d i sa.gr e e m e n t .
W ith t h e p u b l i -
7
c a t i o n of E n g l e r and W e is s b e r g s t h e o r y t h e n e c e s s i t y o f t h e p r e s ­
e n c e o f oxy.geh i n t h e
o x i d a t i o n o f f a t s was a c c e p t e d .
oxygen c o n s u m p tio n i s m e a s u r e a b l e
of q u estio n ab le
influence
m oisture, m e ta ls,
acid s,
a r e m a n i f e s t e d by t h e
(Salkow oki (1 9 1 9 )} .
in clu d e the n e c e s s ity
gases,
etc.
The a c t u a l
O ther f n c t c t s
of lig h t,
heat,
The e f f e c t
of th e s e f a c t o r s
c h a n g e t h e y p r o d u c e on t h e
in d u c tio n period
of th e f a t .
R itsert
189 0 s u g g e s t e d t h a t t h e c o m b i n e d a c t i o n o f l i g h t
and oxygen w ere n e c e s s a r y o r a t l e a s t t h a t t h e speed of t h e r e a c t i o n
was d e p e n d e n t on t h e l i g h t
he f o u n d t h a t v e r y l i t t l e
in ten sity
since i t
o x y g o n was c o n s u m e d .
th e absence of li g h t
B a lln .n ty n e (1891)
f o u n d t h a t b o t h a i r a n d l i g h t vc-re n e c e s s a r y f o r r a n c i d i t y Y/hen
b l e a c h i n g w as u s e d a s t h e
c r i t e r i o n of r a n c i d i t y .
Coe a n d L o C l e r c
( 1 9 3 4 ) c o n c l u d e d f r o m t h e i r w ork t h a t t h e r a n c i d s t a t e
i s the r e s u lt
o f p h o t o c h e m i c a l a c t i o n duo t o a b s o r p t i o n o f l i g h t p o s s i b l y by a
compound a l r e a d y p r e s e n t
in the
o il.
Coe ( 1 9 3 0 ) p o s t u l a t e s t n c
presence of t h i s
compound ( c h l o r o p h y l l )
a l o n g w i t h t h e compounds
which g iv e r i s e t o t h e f o r m a t i o n o f t h e p e r o x i d e s .
1-ea ( 1 9 3 3 )
u l t r a - v i o l e t and v i s i b l e
lig h t
A ccording to
accelerate
o x idation.
A g e n e r a l c o n c l u s i o n may be d r a w n a s t o t h e r o l e
as follow s:
lig h t.
of lig h t
o x i d a t i v e r a n c i d i t y may t a k e p l a c e i n t h e a b s e n c e o f
The p r e s e n c e
of l i g h t ,
h o w e v e r , may e - e a c o e l e r r t e t h e o x i d ­
a t i o n a s s e e n by a s h o r t e n e d i n d u c t i o n p e r i o d .
t h o method o f d e t e c t i o n o f r a n c i d i t y
lead to th e s e
co n tro v ersies.
cause v a r i a t i o n s
in th e
a r e t h o f a c t o r s v/hich have
The t y p e o f l i g h t
resu lts
The t y p e o f f a t a n d
obtained
s o u r c e may a l s o
(B arnicoat
(1930)).
HEAT
fats.
H e a t i s . d e f i n i t e l y known t o c a t a l y z e t h e o x i d a t i o n o f
o
H y l a n d a n d L l o y d ( 1 9 1 5 ) s t a t e t h a t 50 C i s t h o h o s t t e m p ­
e r a tu r e f o r o x id a ti o n e x p erim en ts as th e p ro d u c ts of o x id a tio n
a re not decomposed.
oxidation i s
F o r most e x p e r i m e n t a l c o n d i t i o n s t h e r a t e
of
s lo w and ti m e c o n su m in g .
f o r may p r o d u c e r e s u l t s
Increased tem perature th e r s o
d i f f e r e n t t h a n t h o s e o b t a i n e d a t 50 C.
L i g h t a nd h e a t may a c t by s u p p l y i n g e n e r g y t o t h e s y s ­
tem (D a v ie s
(1 9 2 8 ) ).
An e l e v a t e d t e m p e r a t u r e c a u s e s a n i n c r e a s e
i n t h e a m ount o f o y x g e n t h a t w i l l d i f f u s e i n t o t h e
fat,
su rface of th e
(Pool (1 9 3 1 )).
WATER
The r o l e o f m o i s t u r e
in oxidative ra n c id ity
more d i s a g r e e m e n t t h a n a n y o t h e r s i n g l e f a c t o r .
c o n s i d e r e d m o i s t u r e a main c a u s e o f r a n c i d i t y .
has caused
B e r t h o l e t 1855
I n 1889 G r d g e r
a n n o u n c e d t h a t f a t s v/e re s p l i t b y w a t e r a n d t h e r e s u l t i n g p r o d u c t s
o f h y d r o l y s i s w e r e o x i d i z e d by o x y g e n .
t h i s by s t a t i n g t h a t r a n c i d i t y i s
B e i l s t e i n 1893 s u b s t a n t i a t e d
d e p e n d e n t o n t h e p a r t i a l d e co m p-
o s itio n of f a t s through m oisture of th e a i r ,
but R itso rt stated th a t
m o is tu r e was n o t a n i m p o r t a n t f a c t o r i n r a n c i d i t y .
N i c o l l e t and L i d d l e
(1916) r e p o r t e d t h a t o x id a tio n of th e
f a t t y a c i d s may t a k e p l a c e i n d e p e n d e n t l y o f t h e h y d r o l y s i s o f g l y ­
c e r i d e s , a s no f r e e
gly cero l is
re c o v e re d from r a n c id f a t s .
Ingle
(1 9 1 3 ) f o u n d maximum a b s o r p t i o n o f o x y g e n i n o i l s t o o k p l a c e i n
dry a i r w h ile m o i s t u r e te n d e d t o lo w er t h i s .
D a v ie s (1928) e x ­
plained t h a t h i^h m o istu re fa v o rs o x id a tio n as a com paratively
la rg e aqueous phase p e rm its easy d i f f u s i o n o f oxygen.
G re e n b a n k ( 1 9 2 4 )
found t h a t m o is tu r e r e t a r d e d
Holm a n d
oxidation of b u tte r
f a t w h i l e s m a l l a m o u n t s h a d no e f f e c t on t h e i n d u c t i o n p e r i o d of
a cod-liver o il- la r d
sam ple.
H. L . S m i t h ( 1 9 1 5 )
s t a t e d t h a t w a te r had l i t t l e
y t i e a c t i o n on f a t s b e l o w 150
0
0
b u t a p p r e c i a b l e a t 200 .
fa v o rin g h y d r o ly s is f a v o r r a n c id developm ent.
cid ity .
C. A. Browne ( 1 9 2 5 )
C onditions
S tokoe (1921) s t a t e s
th a t m oisture i3 th e c h ie f f a c t o r i n causing r a n c i d i t y .
fo u n d t h a t w a t e r e s p e c i a l l y
catal-
K e rr (1981)
i n t h e p r e s e n c e o f l i g h t promoted r a n ­
a g r e e d w i t h Holm a n d G r e e n b a n k t h a t
in th e absen ce o f m o is tu r e a u t o x i d a t i o n p ro c e e d s to th e aldehyde
stage w h ile th e p re se n c e of m o is tu re c a r r i e s th e r e a c t i o n to the
acid s ta g e .
Th e p r e s e n c e o f m o i s t u r e may p o s s i b l y remo ve oxyg e n
from t h e f a t p e r o x i d e t o fo rm t h e f a t o x i d e , h y d ro g e n p e r o x i d e and
ozone ( T s c h i r c h a n d B a r b e n : ( 1 9 2 4 ) ) .
The o z o n e moy t h e n p r o d u c e a
f a t ozonide w hich i s
sp lit
by w a t e r i n t o s i m p l i e r m o l e c u l e s .
The
h y d r o g e n p e r o x i d e may f u n c t i o n a s a b l e a c h i n g a g e n t .
Holm a n d G r e e n b a n k
(1924) found t h a t t h e r e s i s t a n c e to
o x i d a t i o n o f b u t t e r f a t w a s i n c r e a s e d by w a s h i n g o r by p a s s i n g l i v e
steam th ro u g h t h e f a t .
io n of t h e c a t a l y t i c
T h i s r e t a r d i n g may b e d u e t o t h e e x t r a c t ­
s u b s t a n c e s from th e f a t
o r t o a c o n v e r s i o n of
t h e aldehydes t o a c i d s w h i c h g i v e no t a l l o w y o d o r and t a s t e .
As i n t h e
ce.se o f l i g h t ,
t h e c o n c l u s i o n s drawn depend
upon t h e c o n d i t i o n s u n d e r w h i c h t h e e x p e r i m e n t s a r e c a r r i e d o u t .
The r o l e p l a y e d by w a t e r i n t h e o x i d a t i o n o f f a t s
is
still
quest­
ionable .
METALS;
A ll m etals
Henley,
(1922))
catalyze f a t o x id atio n
(Emery and
e ven when t h e y a r e n o t a p p a r e n t l y a t t a c k e d .
th e absence of a i r
ent.
appear to
In
no o x i d a t i o n t a l e s pla .ee w he n m e t a l s a r e p r e s ­
However w h e n f a t s
but absence of l i g h t ,
are
exposed t o a i r i n t h e p r e s e n c e of m etal
o x id a tio n takes place.
They a l s o f o u n d t h a t
l o r d became r a n c i d 'when e x p o s e d t o c o p p e r b o t h i n t h e p r e s e n c e and
absence of a i r .
Copper a c t s
o x id a tio n (D avies (1928)^ .
f a s t e r than le a d ,
It
enhance t h e k e e p i n g q u a l i t i e s
ir o n stro n g ly favors
may be c o n c l u d e d t h a t i n o r d e r t o
of a f a t i t
m u s t be s t o r e d
o u t of
c o n t a c t wi t h m e t a l s .
BACTERIA, MOLDS, EMZYI'SS:
Soxhler in
1385 c o n c l u d e d f r o m work on t h e o x i d a t i o n o f
b u t t e r f a t f r e e from w a t e r ,
c a s e i n and m i n e r a l s a l t s
t h a t m icro­
organism s were n o t p s i g n i f i c a n t f a c t o r i n o x i d a t i o n .
Duclaux
41
1888 e x p r e s s e d t h e o p i n i o n t h a t f a t s w e r e n o t f o o d f o r m i c r o ­
organism s as f a t s
are
in so lu b le
t h a t r a n c i d i t y v/as d u e t o
a s s i s t e d by t r a c e s
in w ater.
enzym es *
K e rr (1921) r e p o r t e d
m olds o r enzymes w ere r e s p o n s i b l e s i n c e
s t e r i l i z e d f a t becam e r a n c i d ,
e n t l y had no e f f e c t .
stated
o x i d a t i o n and h y d r o l y s i s t h e l a t t e r
of l i p o l y t i c
th at n eith er b a c te ria ,
S to k o e (1981)
th u s m icro-organism s,
Here a g a i n t h e
a t i o n v/a.s c o n d u c t e d may l o a d t o
etc.
appar­
c o n d i t i o n s under w hich o x id ­
ambiguous c o n c l u s i o n s .
GASESs
The i n t e r e s t
in the
effect
a t i o n i s due t o t h e p o s s i b i l i t y
ing t h i s
o x id atio n .
o f g a s e s on f a t s d u r i n g o x i d ­
o f s e c u r i n g a means o f p r e v e n t ­
H a ts o x i d i z e most r a p i d l y i n an atm osphere
o f o x y g e n a n d t o a l e s s e r e x t e n t on e x p o s u r e t o a i r .
bon d io x id e and w a t e r a r e removed i r o n t h e a i r ,
V/hen c a r ­
the f a t a c c o rd ­
i n g t o J a k i m e n k o ( 1 9 0 1 ) b e c o m e s r a n c i d more s l o w l y t h a n v/hen e x ­
posed to a i r .
Hext t o
oxygen,
carbon d io x id e i s absorbed r e a d ily
w ith th e developm ent of a s l i g h t
cid t a s t e
(E m er y and H e n l e y
t o bo a b s o r b e d i n b o t h l i g h t
a c i d i t y and a f l a t
(1988)).
but not r a n ­
C a r b o n d i o x i d e was f o u n d
a nd d a r k n e s s .
F a t exposed t o
car­
bon d i o x i d e i n t h e p r e s e n c e o f m e t a l s and l i g h t a t summer t e m p ­
e r a t u r e v n s c e l l e d r a n c i d w h i l e no r a n c i d i t y was d e v e l o p e d when
t h e saine c o n d i t i o n s w i t h t h e
exception th a t a l l
c lu d e d were a p p l i e d t o t h e f a t .
were u n c e r t a i n i f a l l
g a s os w e r e e x ­
These a u th o rs s t a t e d t h a t th e y
o x y g e n o r a i r h a d b e e n e x c l u d e d when c a r ­
b o n d i o x i d e v/as u s e d .
The m e c h a n i s m o f t h e a b s o r p t i o n
u c tio n of a talT ovy t a s t e
o f 00~ w i t h t h e p r c c -
has n ot been e x p la in e d .
I l i t r o g e n anrl h y d r o g e n a r e n o t a b s o r b e d by a f a t ,
a c i d i t y rem ains unchanged,
take p la c e
(R itsert
and Newt on ( 1 9 3 4 )
nitrogen,
B evis
a.nd t h e
a n d no n o t i c e a b l e symptoms o f r a n c i d i t y
(1890)),
even i n t h e p re s e n c e
of l i g h t .
Roschen
r e p o r t e d no c h a n g e i n t h e i n d u c t i o n p e r i o d w i t h
( 1 9 2 3 ) r e p o r t e d t h a t a f a t a f t e r two y e a r s
age i n n i t r o g e n i n t h e p r e s e n c e
o f T i g h t became r a n c i d .
sto r­
This dev­
e l o p m e n t was a t t r i b u t e d t o t h e p r e s e n c e o f l i g h t a l t h o u g h t h e p r e s ­
en ce o f t r a c e s
o f o x y g e n was s u g g e s t e d .
P rese n ce of t r a c e s
of o x y g e n f r e e
o r combined w i t h t h e
f a t as m oloxide oxygen a p p a r e n t l y cause th e f u r t h e r o x i d a t i o n of
th e f a t .
T h u s i n e r t g a s o s o r a v a cu um w i l l n o t s a f e g u a r d a f a t
a g a i n s t o x i d a t i o n v/hen t h i s t y p e o f o x y g o n i s p r e s e n t
and Holm ( 1 9 3 1 )
(Greenbank
a n d Holm, G r e e n b a n k a nd D e y s h e r ( 1 9 3 7 ) ) .
AC IDG:
It
favored i t s
has been su g g este d t h a t th e a c i d i t y
o x idation
ing t h a t th e a c i d i t y
(D avies (I928)a).
of a f a t d i r e c t l y
He e x p l a i n e d t h i s by s u g g e s t
c a u s e d an i n c r e a s e i n t h e
s p e e d of t h e f a t
h y d r o l y s i s a nd t h a t t h u s a. h i g h e r c o n c e n t r a t i o n o f o x i d i z a b l e c o n ­
s t i t u e n t s were p r e s e n t .
o i l and l i n s e e d
w hile o l iv e ,
B allantyne
o il in cresed
rape,
(1891)
found t h a t c o tto n s e e d
in a c i d i t y b e f o r e becoming r a n c i d
c a s t o r a n d p e a n u t o i l s b e ca m e r a n c i d f i r s t .
G r e e n b a c k a n d Holm ( 1 9 2 4 ) f o u n d t h s . t f a t s w i t h t h e l o w ­
e s t acid value evidenced th e b e s t k eep in g q u a l i t i e s
the f a t t y
acids
acted d i r e c t l y as c a t a l y s t s f o r a u to x id a tio n
through l i b e r a t i o n
tic
.
and s u g g e s t e d
of u n s a t u r a t e d a c i d s which a re s t r o n g l y c a t a l y ­
L l o y d ( 1 9 2 7 ) r e p o r t e d t h a t t h e more f a t t y
acids p re sen t
43
the f a s t e r th e
n e u tra l o i l w ill o x id ize.
K e r r and S o r t e r
(1923)
found t h a t on o x i d a t i o n t h e f r e e
f a t t y a c i d s show a s l i g h t i n c r e a s e ,
a nd t h e n a d e c r e a s e a t w h i c h
t i m e t h e p h y s i c a l s i g n s of* r a n c i d i t y o c c u r .
causes an i n c r e a s e i n f r e e f a t t y
acid s.
F u rth er o x idation
They f o u n d a l s o t h a t r a n ­
c i d i t y t a k e s p l a c e w i t h o u t h y d r o l y s i s w hich would have c au sed an
increase in a c i d i t y .
I t is
now g e n e r a l l y r e c o g n i z e d t h a t t h e r e
c o r r e l a t i o n betw een f r e e
coat (1931)),
fat
(D avies
(1930)
(1931)).
S tearic
a c i d h a s b e e n r e p o r t e d a s one
(Yamaguchi (1931)
i n c r e a s e s t h e r a t e o f f o r m a t i o n o f com­
pounds c a u s i n g t h e K r e i s t e s t
(Jones
(1924)),
The a d d i t i o n t o
o f a c i d s i n q u a n t i t i e s b a r e l y d e t e c t a b l e by t i t r a t i o n
w i l l change th e
The q u a n t i t a t i v e
ing p r i n c i p a l l y
oxidation
su scep tib ility
e ffe c ts are
lin o leic
of th e b u t t e r o i l to o x id a tio n .
n o t so g r e a t when t h e f a t s
a c i d were u s e d .
Jlicindleic
contain­
acid re ta rd s
(H o lm , G r e e n b a n k a n d D e y s h e r ( 1 9 2 7 ) ) ,
The f o l l o w i n g i s
a c l a s s i f i c a t i o n of v a rio u s a cid s w ith
r e s p e c t t o t h e i r a c t i o n on a l a r d - c o d - l i v e r o i l m i x t u r e
(1934).
(B arni-
M o st a c i d s w i l l s h o r t e n t h e i n d u c t i o n p e r i o d o f a
Free o le ic a c id
butter o ils
no a b s o l u t e
f a t t y a c i d c o n t e n t a nd r a n c i d i t y
of th e a c id s w hich s h o r t e n t h e i n d u c t i o n p e r io d
(1932)).
is
Tannic a c i d ,
tartaric
acid,
w e r e f o u n d t o h a v e no e f f e c t on t h e
acid shortened th e
c irtic
(O lcott
a c i d and m a l e i c a c i d
in duction p erio d .
Perbenzoic
induction p erio d .
O l c o t t and M a t t i l
(1936«$- o b t a i n e d t h e f o l l o w i n g r e s u l t s
( T a b l e I', on t h o i n d u c t i o n p e r i o d o f t h e c r u d e e s t e r s
of hydro-
44
gen a ted
co ttonseed o i l .
T a b le I
C lassificatio n
of various
a c i d s a s t o t h e i r e f f e c t on
th e o x id a tio n o f t h e crude e s t e r s of hydrogenated c o t ­
tonseed o il
I n a c t i v e A cids
Acids A c tiv e as I n h i b i t o r s
Formic A cid
O x a lic A cid
A c e tic Acid
lualonic Acid
L a c t i c Acid
T a r t a r i c Acid
S u c c i n i c Acid
l i a l e i c Acid
A dipic Acid
C i t r i c Acid
If uc ic A c i d
I t a l i c A c id
A z e la ic Acid
P v r u v i c Acid
D ih y d ro x y s te a r ic A cid
A sp s.rtic Acid
%
Benzoic A cid
P h t h a l i c A cid
Holm a n d G r e e n b a n k ( 1 9 £ 4 )
f a t was e x p o s e d t o a i r
cep tib ility
fa tty acids.
( 1 9 3 6 ) f o u n d t h a t when b u t t e r -
o
.
,
a t 95 C i n t h e a b s e n c e o f l i g h t ,
.
its
sus­
t o a u t o x i d r . t i o n was o f f o c t e d by t h e p r e s e n c e o f v a r i o u s
Thoi
r
r e s u l t s may be f o u n d i n T a b l e I I .
Table I I
The e f f e c t o f t h e a d d i t i o n o f v a r i o u s f a t t y
a c i d s on t h e
o x idation of b u tte r f a t
C olor
Sa mple
K reis Tost
n atu ral
B u tterfat
0
B u tterfat
+ B u t y r i c Ac i d
B u tterfat
4*
B u tterfat
+ G a p r o i c Ac i d
B u tterfat
4*
O l e i c Ac,id
C om pletely blenched
12
B u tterfat
+ O le ic A cid
C om pletely bleached
GO
From t h e s e
V aleric
A cid
Very s l i g h t l y
bleach ed
1
Very s l i g h t l y
bleached
1
1.2
B leached
r e cm I t s t h e y c o n c l u d e d t h a t f r o c
f a tty acids
catalyzed
t h e o x i d a t i o n and t h a t t h e g r e a t e r t h e m o l e c u l a r w e i g h t , t h e
g re a ter the
cataly tic
cataly tic e ffe c t
pow er.
O leic a c id , th e y r e p o r te d ,
n o t only to i t s
owed i t s
a c id ic p r o p e r tie s but also to
t h e e a s e w i t h w h i c h i t w a s o x i d i z e d and t h e c a t a l y t i c a c t i o n o f t h o
by-products of o x id a tio n .
hydrolysis
through th e
of th e
They s u g g e s t e d t h e a c i d s
glycerides
p o ssib ly aided
and a l s o s e r v e d a s o x y g e n c a r r i e r s
f o r m a ti o n of p e r - a c i d s .
in th e f o r m a t i o n o f i n t e r m e d i a t e
The p o s s i b i l i t y
of a id in g
co mp ou nd s a s w e l l a s t h e p o s s i b l e
r e n r r a n g e n e n t i n v o l v e d i n t h o p r o d u c t i o n of t r . l l o v / i n e s s was s u g ­
gested.
By n e u t r a l i z i n g t h e b u t t e r f a t w i t h d i l u t e
i d e , f o l l o w e d by 8. t h o r o u g h w a s h i n g and d r y i n g ,
shortened in d u c tio n p e r io d .
took p la c e
as th e
sodium h y d ro x ­
thoy o b ta in e d a
A pparently h y d ro ly s is of g ly c e r id e s
f a t was s t i l l
acid.
The w a s h in g p o s s i b l y
moved t h e a n t i o x i d a n t s v /h ic h w or e w a t e r s o l u b l e .
re­
The r o l e t h a t t h e f r e e
has n o t b e e n d e f i n i t e l y
f a t t y a c id s play in f a t
determ ined.
L-ost f a t t y
acids
o xidation
seem t o
shorten th e
i n d u c t i o n p e r i o d and c a u s e an i n c r e a s e i n t h e r a t e
oxidation.
The p r e s e n c e o f m o i s t u r e may c h a n g e t h e p i c t u r e a s may
the p re s e n c e of o t h e r m a t e r i a l s
in the f a t.
of
The a c c u r a c y w i t h w h i c h
t h e r e l a t i v e r a t e s o f o x i d a t i o n a r e d e t e r m i n e d may b e q u e s t i o n e d .
S u f f i c i e n t e v i d e n c e f o r t h e c o n c l u s i o n s d r a w n by Holm a n d G r e e n b a n k
as t o t h e r o l e
of i n c r e a s in g m o le c u la r w eight of th e f a t t y a c id c a t ­
aly st is not o ffe re d .
has no d i r e c t
I t has been d e f i n i t e l y proved t h a t a c i d i t y
c o rre la tio n w ith ra n c id ity .
p a r a lle l w ith a c id ity
R a n c id ity does not run
(S m ith (1 9 1 5 )).
PRO-OXIDANTS:
The a b i l i t y
o f a s u b s t a n c e t o a c t a s a p r o - o x i d a n t has
r e c e i v e d some a t t e n t i o n .
M attill
(1931) r e p o r t s t h a t t h e n a t u r a l
p r o - o x id a n ts a r e found i n t h e n o n - s a p o n i f i a b l e c o n s t i t u e n t s
f a t s and o i l s .
of the
P e r o x i d e s w e r e r e p o r t e d by R o s c h e n a n d Newt on ( 1 9 3 4 )
t o be i n a c t i v e d u r i n g o x i d a t i o n w h i l e t h e a c t i v e m a t e r i a l was a
o
h i g h m o l e c u l a r w e i g h t s u b s t a n c e w h i c h was n o t v o l a t i l e a t 200
and 3 - 5 mm. H e p t a l d e h y d e d o e s n o t a c t a s a p o s i t i v e
o
l a r d a t 70 C ( R o s c h e n a n d Newt on ( 1 9 3 4 ) ) w h i l e f a t t y
ate o x id a tio n
(Greenbank
(1936)).
l a r d w i l l act- a s a c a t a l y s t t o
ta in active
I t was r e p o r t e d t h a t o x i d i z e d
c a t a l y t i c m a t e r i a l ( R o s c h e n a nd N e w t o n ( 1 9 3 4 ) ) .
in series
Greenbank (1936) fo u n d t h a t t h e l a s t
the f i r s t
acids a c c e le r­
f r e s h l a r d and t h e r e f o r e m ust c o n ­
co n n ectin g t h r e e sam ples of a f a t
then,
c a ta ly s t for
sample o x i d i z e d l a s t .
By
and d r a w i n g a i r t h r o u g h
sample o x i d i z e d f i r s t ,
T h i s i n d i c a t e d t h a t t h e p r o - c::14 -
47
o x id a n t m a t e r i a l was v o l a t i l e
bank ( 1 9 3 6 ) ) .
( G r e e n b a n k a n d Holm ( 1 9 2 4 ) a n d G r e e n ­
The a u t h o r s a l s o r e p o r t e d t h a t t h e a b i l i t y f o r a
su b sta n c e t o a c t as a p r o - o x i d a n t o r a n t i o x i d a n t depended upon i t s
o x i d a t i o n - r e d u c t i o n p o t e n t i a l and i t s
d is so c ia tio n constant.
ANTI-OXIDANTS:
C o n s i d e r a b l e w o r k h a s b e e n do n e o n t h e n a t u r e a n d mode
of a c t i o n o f a n t i o x i d a n t s
on f a t s
tectiv e fa c to r
c o n s id e r e d as th e r a t i o
(P. F .)
is
of t h e i n d u c t i o n p e r i o d w i t h t h e
tected f a t
(O lcott (1 9 3 4 )),
a nd o i l s .
not r e l a t e d a c c o r d i n g t o O l c o t t .
c o tt and M a t t i l l
(1936))
index or th e p ro ­
of the le n g th
i n h i b i t o r to th a t of the unpro­
The a c t i v i t y
of t h e p h e n o l i c t y p e a r e a c t i v e
Its
and r e d u c i n g a c t i o n a r e
H y d r o x y l compounds e s p e c i a l l y
in h ib ito rs
and t h i s
( O l c o t t (1934) and Ol­
a c t i v i t y may be d e s t r o y e d by
e s t e r i f i c a t i o n a n d by r e a g e n t s w h i c h a r e known t o a t t a c k t h e u n ­
saturated lin k ag e.
Some n a t u r a l a n t i o x i d a n t s may be removed f r o m
t h e o i l by b o i l i n g w i t h w a t e r .
(w ater s o l u b l e f r a c t i o n )
is
H ow eve r t h e r e s u l t i n g m a t e r i a l
in activ e
( B a nks and H i l d i t c h ( 1 9 3 2 ) ) .
A ntioxid.ants a re a l s o found in t h e u n s a p o n if ia b le
fr a c tio n of n a tu r a l o i l s
ently la ck
nitrogn,
and f a t s
(M attill
(1931)).
s u l f u r and t h e h a lo g en s
A ntioxidants are u su ally
easily
(O lcott
oxidizablc
They a p p a r ­
(1934)).
compounds
c a p a b l e o f u t i l i z i n g a ny o x y g e n w h i c h may b e a c t i v a t e d
i
w ith t h e f a t a c c o r d in g t o D avies
(1936)
state
th at
in h ib ito ls
solely
i n i t i a l p e r o x i d e end a r e o u t i r e l v
begins.
They b e l i e v e t h a t
(1.931).
in contact
H a m i l t o n a nd o l c o t t
i n h i b i t t h e f o r m a t i o n o f t;ie
destroyed before rapid
oxictutr.cn
th e a n t io x id a n ts prove nt t e c i o m n i i o n
of c h a i n s o f a p p r e c i a b l e l e n g t h .
oxidation s t a r t s ,
the
When a n i n h i b i t o l i s ad d ed a f t e r
o r i g i n a l m o l o x i d e a nd t h e p e r - a c i d s a r e d e s ­
t r o y e d b u t n o t s e c o n d a r y p e r o x i d e s i n t o w h i c h t h e mot o x i d e s a r e
norm ally t r a n s f o r r a e d ,
French,
O l c o t t a nd H a t t i l l
of t h e a n t i o x i d a n t r e s i d e s
in i t s
(19 35)
state
t h a t the e f f e c t
a b i l i t y to d estro y active p e r­
oxides.
I t n a y t h u s b e s e e n t h a t n o t t o o much i s known o f t h e
n a t u r e a n d a c t i o n o f a n t i o x i d .ant s d u r i n g a u t o x i d a t i o n o f f a t s a n d
s
o ils.
ot : e r f a c t o r s :
The r o l e o f g l y c e r o l i n t h e
m atter of concern a t
volved i n th e
one t i m e .
o x idation
o x i d a t i o n o f f a t s v;r,n a
Some w o r k e r s b e l i e v e d i t w s i n ­
(L arn p ett a n d S y l v e s t e r
(1931)).
The
p r e s e n t t h e o r y h o l d s t h a t g l y c e r o l h a s no p a r t i n t h e o x i d a t i o n ,
THnfel and C e r c z o
(1997).
The t y p e o f f a t b r i n g o x i d i z e d h a s .an i n f l u e n c e on t h e
rancidity r e s u l t s ,
of v e g o t a b l o o r i g i n ,
A n i m a l f a t s be com e r a n c i d m o re r a p i d l y t h a n f a i n
as c o rn o i l and c o t t o n s e e d o i l .
This i s p r o ­
b a b l y duo t o t h e t y o e o f f r x t t y a c i d s p r e s e n t a s wo 11 a s t h e n a t u r a l
antioxidants p resen t
( T r i e b o l d , ’/e bb a nd Rudy ( 1 9 3 3 ) ) .
f a t decom position is
a f f e c t e d by l i g h t ,
a c id and t h e c o l o r i n g n a t t e r
in th e f a t .
the q u a n tity
R ancidity
A n im a l
of freo
oleic
i s promoted
oy l i g h t f r o m t h e b l u e a n d n i l r n . - v i o 1 e t «
T h a t t h e d i f f orr-'-ce b e t w e e n a r t i f i c i a l
ation is
one o f d e g r e e o r p e r h a p s
a n d nr t u r u l o x i d ­
o n l y one: o f t i m e m ’ h e r t h a n r.
c o m p l e t e l y d i f f e r e n t k i n d o f o x i d a t i o n we.s s u g g e s t e d by H i c o l l e t
and L i d d l e
(1916).
A c c o r d i n g t o H a m i l t o n a nd O l c o t t
(1937)
n atu ral fa ts
and o i l s may p r o d u c e two k i n d s o f c h a n g e s i n t h e p r e s e n c e
gon end a i r .
F irst,
of oxy­
m ore h i g h l y u n s a t n r a t e d o r d r y i n g o i l s
oxygen a n d p o l y m e r i z e t o f o r m s t a b l e f i l m s .
Second,
less
absorb
satu rated
f a t s p,bsorb o x y g e n more s l o w l y a n d become r a n c i d .
From a s t u d y o f o x i d a t i o n
fo un d t h a t a i r a c c e l e r a t e d t h e
c o lo r , on i n c r e a s e
of o l i v e
o i l H olland
(1918)
o x i d a t i o n a s d e t e r m i n e d by l o s s
i n s a p o n i f i c a t i o n numb er a n d a l d e h y d e
number,
and a d e c r e o . s e i n i o d i n e n u m b e r .
L i g h t accele.rn.ted t h e s e
w h i l e m o i s t u r e s how ed v e r y l i t t l e
effect.
light increased the
Greenbank
stitu en ts
resu lts
A ir in th e p re sen c e
of
a c id v a lu e as a ls o did th e a d d itio n o f m o is tu re .
(1936)
r a te of o x i d a t i o n o f f a t s
saturated f a t t y
of
summ arizes t h e f a c t o r s
i n s t o r a g e by ( l )
acid c o n s titu e n ts
actin g as pro-oxidants
in flu e n c in g the
k i n d a n d am ount o f u n ­
of the g ly c e rid e s ,
and a n t i - o x i d a n t s ,
(3 )
(3)
th o s e con­
conditions
t o which t h e f a t h a s b e en s u b j e c t e d .
G. A. Browne ( 1 8 9 9 )
c o n c l u d e s t h e t h r e e f a c t o r s most
activ e in th e p ro d u c tio n o f r a n c i d i t y a re exposure to
and. h e a t .
air,
lig h t
G i v e n s u f f i c i e n t t i m e d e c o m p o s i t i o n may o c c u r w i t h
s u p p r e s s i o n o f a ny one o r e v e n t w o o f t h e s e f . a c t o r s .
oxidation i s
obtained w ith a l l th r e e .
Lost ra p id
OXIDATION OF FATSj
A f t e r a m o le c u le o f oxygen has a t t a c h e d i t s e l f t o t h e
double bond o f t h e
takes p l a c e .
peroxide.
f a t m o le c u le , d e c o m p o s itio n o f th e m oloxide
The f i r s t p r o d u c t w h ic h c a n be r e c o g n i z e d i s t h e
D e c o m p o s itio n t h e n p r o d u c e s numerous p r o d u c t s ,
as a l d e h y d e s , k e t o n e s ,
such
a c i d s and v a r i o u s o t h e r s u b s t a n c e s .
p r o d u c t i o n o f t h e r a . n c i d o d o r and t a s t e
decom position p r o d u c ts .
is
due t o
The
some o f t h e s e
The n a t u r e a n d c o m p o s i t i o n o f t h e o r i g ­
in a l f a t and t h e c o n d i t i o n s u n d e r w hich o x i d a t i o n t a k e s p l a c e ,
con trol th e type of p ro d u cts
obtained.
The f o l l o w i n g a c i d p r o d u c t s f o u n d a f t e r o x i d a t i o n
have b e e n r e p o r t e d :
nonylic, c a p r y l i c ,
form ic,
e.cry lic,
stearic_j d i k e t o s t e a r i c
acids
O enanthylic, p e la r g o n ic ,
fatty acid s
(as c a p ric
acetic,
azelaic,
b u ty ric,
caproic,
h ep ty lic,
h y d r o x y s te a r ic , dihydroxy-
( P r i t z k e r and Jungkunz ( 1 9 2 8 ) ) .
c ap ric acids
and c a p r y l i c )
(B evis
(1923)).
V olatile
and n o n - v o l a t i l e a c id s
(h y d r o x y p a lm itic and h y d r o x y o l e i c ) Salkow sR i (1 9 1 9 ). A z e la ic
acid i s t h e
norm al p r o d u c t o f a r t i f i c i a l o x i d a t i o n of t h e Var­
ious u n s a t u r a t e d f a t t y
acids)
acids
(o leic,
lin o leic
and l i n o l e n i c
a s no C = C o c c u r s b e t w e e n c a r b o n a t o m numb er 9 a n d t h e
COOH g r o u p
( N i c o l e t and L i d d l e
(1915)).
The a l d e h y d e s w h i c h h a v e b e e n r e p o r t e d a r e :
aldehyde,
c ap ro ic aldehyde,
(S cala ( 1 9 0 8 ) ) .
o e n e n t h y l i c , p e la r g o n ic aldehydes
A c r o l e i n h a s b e e n r e p o r t e d by D u n l a p a n d S c h e n k
(1903) a n d h e p t y l i c
elenic a c i d ,
butyr-
and n o n y lic a ld e h y d e s ,
h a l f a ld e h y d e o f pim-
c r o t o n i c a l d e h y d e and f o r m a l d e h y d e by P r i t z k e r a nd
Ju n g k u n z ( 1 9 2 8 ) .
O t h e r c o m p o u n d s r e c o g n i z e d among t h e r a n c i d compounds
are:
carbon d io x id e from b u t t e r
(G a rd n e r (1914)) and King (1 9 1 5 ) ) .
M ethyl g l y o x a l , d i h y d r o x y a c e t o n e and o l e i c a c i d o z o n i d e ( P r i t z k e r
i
and J u n g k u n z ( 1 9 2 8 ) .
H a nu s ( 1 9 0 0 ) b e l i e v e d t h a t u n s a t u r a t e d a c i d s
formed l a c t o n e s u n d e r i n f l u e n c e o f a i r
T a f f e l and R e v is
(Hepburn s c i t a t i o n ) .
(1931) r e p o r t e d - t h a t v a r i o u s forms of
p e r o x i d e s may b e f o r m e d d u r i n g o x i d a t i o n .
t e m p e r a t u r e s a r e r e d u c e d by H I , w h i l e a t
P e r o x id e s form ed a t low
0
120 more p e r o x i d e s a r e
fo r m e d t o g e t h e r w i t h o t h e r f o r m s o f c o m b i n e d o x y g e n w h i c h a r e n o t
o
so r e a d i l y r e d u c e d by H I .
A t 17 0 o i l s c o n t a i n p e r o x i d e s w h ic h
are only d i f f i c u l t l y
red u cib le.
Compounds r e s p o n s i b l e
fo r the
r a n c i d odor o f f a t s are
h e p t y l and n o n y l a ld e h y d e s a c c o r d i n g t o P o w i c k ( 1 9 2 3 ) .
o f a c r o l e i n w as n o t e d by D u n l a p a n d S c h e n k
The odo r
(1903) when l i n s e e d
o i l was d r i e d .
W i t h t h e e x c e p t i o n o f t h e o x y g e n c o n t a i n i n g compounds
of the o r ig i n a l f a t t y
acid s,
all
o t h e r o x i d a t i o n p r o d u c t s con-
td n a low er c arb o n c o n te n t th a n th e o r i g i n a l f a t t y a c i d s
(Spaeth
(1896)).
A ccording t o
fatty
N i c o l l e t and L i d d l e
(1916) u n s a t u r a t e d
a c i d s w i t h one d o u b l e b o n d y i e l d o n o x i d a t i o n o n l y v o l a t i l e
products.
F a t t y a c i d s w i t h s e v e r a l d o u b l e bonds l e a v e
add o x y g e n t o t h e
o thers
one i n t a c t ,
a n d a b s o r b o x y g e n t o f o r n a n OH g r o u p
w ith th e p r o d u c tio n o f hydroxy a c i d s .
the fo rm ation of a n h y d rid e s.
The OH g r o u p s may c a u s e
Ingle
( 1 9 1 3 ) r e p o r t e d t h a t o x i d i z a b i l i t y d e p e n d s on t h e
number o f C = C g r o u p s .
The f o l l o w i n g i n d i c a t e s t h e p o s s i b l e r e -
a c t i o n s t h a t t h e f a t p e r o x i d e s a n d o x i d e s may u n d e r g o e i t h e r t h r o u g h
rearrangem ent or deco m p o sitio n :
-CH
!>
-CH
-C = 0
I
-CH 2
— -
-CH - 0
I
I
-CH - 0
-CH - 0
|
I
-CH - 0
-CH - 0
I
I
-CH - 0
-C = 0
|
-CHOH
—
^
-----
-CKO
+
-CHO
-COOH
+
-CHgOH
HP0 _
OXIDATION OF OLEIC ACID:
F a h r i o n (1893)
and o i l s ,
unsaturated
only v o l a t i l e
stated th at
d uring the o x id a tio n of f a t s
a c i d s w i t h one d o u b l e bond u s u a l l y f u r n i s h
a n d no s o l i d o x i d a t i o n p r o d u c t s .
i n g more t h a n on e d o u b l e b o n d ,
In a cid s c o n ta in ­
one o f t h e bonds r e m a in s i n t a c t ,
th e o t h e r s o pen an d o ay g en atom s add t o
each.
O th e r oxygen atoms
e n t e r b e t w e e n c a r b o n a n d h y d r o g e n b o n d s f o r m i n g OH g r o u p s .
P oly­
m e r i z a t i o n may o c c u r a t t h e i n t a c t d o u b l e b o n d s w h i l e a n h y d r i d e
f o r m a t i o n ma.y a l s o t a k e p l a c e
s in c e hydroxyl groups are p r e s e n t .
D i f f e r e n t s t a g e s o f o x i d a t i o n may o c c u r a t t h e same t i m e .
As a n e x a m p l e o f a t y p i c a l u n s a t u r a t e d f a t t y
o x id atio n o f o l e i c a c id has been w id e ly s tu d ie d .
acid,
the
Numerous a t t e m p t s
t o o b t a i n t h e p u r e a c i d h a v e b e e n made b o t h s y n t h e t i c a l l y a nd f r o m
natural o ils
such as o liv e o i l ,
a c i d and i t s
esters
other u n s a tu ra te d
etc.
The b o i l i n g p o i n t s
occur too close t o those of th e
a c i d s a nd e s t e r s t o
s a t u r a t e d and
p r o v i d e a r e a d j r me an s o f
o b t a i n i n g t h e p u r e a c i d by d i s t i l l a t i o n .
be c a r r i e d
of the
Any d i s t i l l a t i o n m u s t
out under reduced p re s s u re to p rev en t decom position
and o x i d a t i o n o f t h e a c i d .
t o be u n s a t i s f a c t o r y ,
C hem ical m ethods have a l s o b e e n found
a s m o s t o f t h e m r e l y on p h y s i c a l s e p a r a t i o n s
of th e p re p a re d d e r i v a t i v e s .
These m ethods i n c l u d e th e f o r m a ti o n
of t h e b rom ine d e r i v a t i v e s , t h e
lead s a l t s ,
o f s e p a r a t i o n d e p e n d on t h e r e l a t i v e
etc.
differen ces
P h y s i c a l methods
of the p h y s ic a l
constants.
As a r e s u l t o f t h i s
acid ),
it
is
( p r e p a r a t i o n of p u r e o l e i c
r a t h e r d o u b tfu l t h a t p u re o le ic a c id has been used in
th e g r e a t e r number o f t h e
study of th e
d ifficu lty
o x id a tio n experim ents.
N evertheless, a
o x i d a t i o n p r o d u c t s has p ro d u c e d c e r t a i n ev id en c e
r e l a t i v e t o t h e m echanism of t h e r e a c t i o n .
of f a t s and o i l s ,
As i n t h e o x i d a t i o n
c o n d itio n s u n d e r w hich th e r e a c t i o n is c a r r i e d
out c o n tr o l th e r e s u l t s
o b tained.
The f o l l o w i n g e q u a t i o n s may s e r v e t o i l l u s t r a t e
anism of t h e
t h e me ch­
o x i d a t i o n o f o l e i c a c i d a s p o s t u l a t e d by v a r i o u s
w orkers.
Th e s i m p l e s t e x p l a n a t i o n o f t h e o x i d a t i o n i s i l l u s t r a t e d
by P o w ic k
(1923):
54
CHg
t
(CH2 ) v
1
HC
11
o2
HC
-----
OH,
(CH2 ) 7
j
HC - 0
I
1
HC - 0
CH3 ( C P ^ s ) 7CH0
P elarg rro n ic
.
------- *_
CH3 (CH2 ) 7C00H
aldehyde
P e la rg o n ic acid
+
.
j
(ck2 ) 7
1
(CH2 ) 7
H 0 0 C ( G ? H 2 ) 7CH0
------
hooc ( ch 2 )
7cooh
f
COOH
COOH
A z e la ic
To e x p l a i n t h e f o r m a t i o n o f t h e m o r e
CH3
1
ch 3
(ch 2) 5
I
HCH
I
HCH
(ch2)5
HCH
HCH
HC
o.
II
HC
I
HCH
I
H.CH
I
( ch 3 ).
I
COOH
HC
HC
c o m p l e x p r o d u c t s , Powiclt s u g g e s t s :
ch3
I
( ch 2 ) 5
I
HC
II
HC
I
HC.
0 2 0 2
HC
I
I-IC
I
0
h a l f aldehyde A z e la ic a c id
CII3
CH3
I
(CHS ) 5
I
HC
-
0
I
HC
-
COOH
I
4-
0
CHO
1
HC
(
H (\
HC
t
HC
HC
-
0
-
0
I
I
( GH2)5
1
COOH
COOH
H ep t a l d e h y d e
Ox ide o f
0
I
j e r o x i d e HC
I
(CH2 ) 5 o x y g e n
(CIi2 ) 5
I
(ch2)5
!
CHO
HC
I
HC = 0
+HC = 0
I
(ch2) 5
I
COOH
riutandial
H alf aldehyde
of pim elonic
acid
O leic Acid
O leic a cid
O x id e o f
Peroxide
9-10,
r7~ —8 , D o u b l e
1 1 -H_ 2
lin o len ic
HC = 0
1
HC\
0
HC
I
HC = 0
-CO
oxide of b u t e n d i a l
CH2
^
®
Ct11
*r
CHO
“0 2
peroxide
s -c id j o f oxide
ep5_3nydrinaldehyde
COOH*
- c o 2
[
LTf
I\
*-----
HC
CHO
oxide of a c r o l e i n
carboxvlio acid
55
T s c h o r i c h (P o v /i c k ( 1 9 5 3 ) )
d i f f e r e d w i t h P o w ic k i n . t h a t t h e p e r o x i d e
i s d e c o m p o s e d by w a t e r t o f o r m t h e o x i d e ,
Ozone i s
now t h e
reactiv e
su bstance,
an o z o n i d e w h i c h i n t u r n i s
ozone and h y d ro g e n p e r o x i d e .
re a c tin g w ith th e
d e c o m p o s e d by w a t e r .
oxide t o g iv e
In h is
l i c a t i o n T sc h o ric h su g g e sts hydrogen p ero x id e in s te a d
1925 p u b ­
of ozone i n
the r e a c t i o n :
c:r3
Clio
1 J
i
Clip) 7
I
CH
l(
°2
CH
1
C'-ia) 7
1
CO Oli
( G-IS ) 7
1
HC - 0
1
1 HoO
HC - 0
!""
1
(CHo) 7
1
COOH
CIi3
I
(CII3 ) 7
1
EC.\
0,3 on
HoGo
1 0
IIC' + 0 ,3 +
. o Go
/ r \
/.-"M
^ ij ilc 1n
1
COOH
»
holm s m o d if ie d i d e a i s
of the
»
seme n a t u r e a s T s c h o r i c h s .
Browne p o s t u l a t e d t h e f o r m a t i o n o f a f a t t y
when m o l e c u l a r o x y g e n a t t a c k s t h e
break i n t h e
o x i d e and a c t i v e o x y g e n
double bond.
a c t s on t h e g l y c e r i d e s w i t h w h i c h i t
H onylic
aldehyd e,
H onylic
k eto n e,
. AZ0 !Letj-C
aide'.rale,
Pelargonic
acid,
A zelaic
acid.
Clip
1
(OH3 ) 7
1
HC - 0
1
61
HC - 0
1
(O ho)7
1
COOH
The a c t i v o
i s i n c o n t a c t a nd c a u s e s a
chain w ith form ation of f a t t y a c id s,
aldehydes,
bon d i o x i d e , w a t e r a n d o t h e r d e c o m p o s i t i o n p r o d u c t s .
CH3
I
OH3
\
( d ! n ) 7
I
nc
II
HC
Or
---- 1
(CHs ) 7
I
COOP,
Fat e s t e r
Cd3
1
(C--2 ) 7
( 0 H2 ) 7
|
lI
e = o
ncN
1^ 0 + a c t i v e 0 1
Cilo
HC
1
1 rearrange(O -o)7
( CHo) 7
ment
|
I
J
COOR
GOOR
F atty
oxide
h o t cue
oxyg on
j .i -n-j
i
( OH;:) 7
I
COOH
. [o 0
+
n •:
-------- w.;n
1
(Cdg)7
1
COOR
car­
A n o t h e r p o s t u l a t i o n w a s made t o
ber of th e
o leic
ex p lain the in c re ase
i n a c c j t y l num­
a c i d on o x i d a t i o n :
gh3
I
gh3
I
(ch2)7
(cii2 ) 7
'
lie - 0
1
|
HC - 0
1
(CH2 ) 7
I
COOR
i
HC - OH
I
HCl - OH
/
(CII2 ) 7
H2 0
5=—
+
0 (activ e)
I
COOR
.fatty p e ro x id e
fatty
dihydroxide
S t i l l a n o t h e r a u t h o r (li eu (19 33). )
suggests the follow ­
in g mechanism:
O l e i n on o x i d a t i o n y i e l d s
o u te r d o u b le bonds a r e s e l e c t i v e l y
lin o len ic
acid' e s t e r .
The two
o x id iz e d w ith th e fo rm a tio n of
an u n s a t u r a t e d d i p e r o x i d e w h i c h d e c o m p o s e d t o f o r m h y d r o g e n p e r o x i d e
and t h e d i m o n o x i d e e s t e r o f l i n o l e n i c
acid.
A bsorption of w ater
p ro d u c e s t h e t e t r a - h y d r o x y a c i d e s t e r w h ic h s p l i t s and y i e l d s h e p t aldehyde, m aleic
bon m o n o x i d e
a ld e h y d e , h a l f aldehyde
of
and m a l e i c a n h y d r i d e w h ic h i s
a c r o l e i n and f i n a l l y
ep ih y d rin aldehyde.
pim elic acid e s t e r ,
car­
f u r t h e r decomposed t o
L i n o l e i n and l i n o l e n i n
give s i m i l a r r e a c t i o n s .
The p o s t u l a t i o n o f t h e f o r m a t i o n o f a c y c l i c
has a l s o b e e n s u g g e s t e d
It
(E llis
stru ctu re
(1926)).
i s r e p o r t e d by R u e m e le ( 1 9 3 4 ) t h a t m e t h y l o l e a t e
t u r n s r a n c i d m ore r e a d i l y t h a n t h e m i x e d m e t h y l e s t e r s o f o l e i c
and l i n o l e i c
that o le ic
acids.
However, T& ufel and M tille r (1930) r e p o r t e d
a c i d and e t h y l o l e a t e a b s o r b e d oxygen a t a p p r o x i m a t e l y
57
t h e same r a t e
a s d e t e r m i n e d hy t h e i n c r e a s e i n w e i g h t .
TEMPERATURE' OF OXIDATION OF OLEIC ACID;
The t e m p e r a t u r e
a t which o l e i c
the r e s u l t s w hich a r e o b t a i n e d .
acid is
Hyland and L loyd (1915)
as t h e d e s i r a b l e t e m p e r a t u r e f o r t h e
oxidation.
r e p o r t 50°C
In t h r e e months o l ­
e i c a c i d sh ow ed a maximum g a i n i n w e i g h t o f 5 , 8 ^
o x id a tio n went t o
oxidized in flu en ces
In dry a i r the
c o m p le tio n , w hile th e p resen ce of m o istu re p re ­
vented t h e o x i d a t i o n of t h e
g ly cerid es but a s s is te d the oxidation
i n t h e c a s e o f t h e f rutty a c i d s ,
O
At 100 C n o n - c a t a l y t i c
o x id a tio n of o le ic a c id , S kellon
(1 9 3 1 ) r e p o r t e d a t e n f o l d i n c r e a s e i n p r o d u c t i o n o f t h e v a r i o u s
a c id s a l r e a d y r e p o r t e d by o t h e r a u t h o r s ,
of 9-10 d i h y d r o x y s t e a r i c
hydroxy and i s d o l e i c
acid ,
acids
such as th e p ro d u c tio n
crude non oic a c i d , a m ix tu re of
a n d some f o r m i c a n d a c e t i c
a c i d 3 . Hy~
0
l a n d a nd L l o y d ( 1 9 1 5 ) r e p o r t e d t h a t t h e o x i d a t i o n a t 98 g a v e p r o ­
ducts to o u n s t a b l e f o r a n a l y s i s .
Loss i n w e ig h t took p l a c e b e fo re
th e t h e o r e t i c a l i n c r e a s e was o b t a i n e d .
O x id a tio n o f o l e i c a c id (S k e llo n (1931)) f o r s h o r t
o
p e r i o d s a t 120 C w i t h a c a t a l y s t i n t h e f o r m o f a t r a c e o f blown
v/hble o i l p r o d u c e s 9 - 1 0 d i h y d r o x y s t e a r i c a c i d ,
10 h y d r o x y s t e a r i c , c r u d e h y d r o x y a c i d s ,
i s B o l e i c a c i d and t r a c e s
form aldehyde.
azelaic acid ,
a m ixture c o n tain in g
of form ic, a c e tic
a n d o x a l i c a c i d s and
No e v i d e n c e o f t h e m i g r a t i o n o f t h e e t h y l e n i c l i n k ­
age was f o u n d w he n g a s e o u s o x y g e n r e a c t e d w i t h t h e u n s a t u r a t e d
acid.
58
TASTE AND ODOR:
T a s t e a nd o d o r may be u s e d t o d i s t i n g u i s h b e t w e e n f r e s h
and r a n c i d f a t s .
T h e s e o r g a n o l e p t i c t e s t s h o w e v e r g i v e no i n d i c a ­
ti o n o f t h e e x t e n t t o w hich o x i d a t i o n has p ro c e e d e d .
I t has been
f a i r l y d e f i n i t e l y e s t a b l i s h e d t h a t a f a t a p p e a r s f r e s h as lo n g as
i t is w ith in the
induction p e rio d .
i s r e a c h e d , an o f f t a s t e
Once t h e end o f t h i s p e r i o d
a nd o d o r may be n o t i c e d .
The p r e s e n c e
of o t h e r o d o r i f e r o u s m a t e r i a l s may h o w e v e r mask t h e s e c h a r a c t e r ­
istics.
D avies
at ion of f a t s .
(1931)
s t a t e s th a t t a i n t is a r e s u l t of uutoxid-
The i n i t i a l o f f - t a i n t may be duo t o
organic p e r ­
o x i d e s s u p p l e m e n t e d by v e r y s m a l l t r a c e s o f d e g r a d a t i o n p r o d u c t s
of o l e i c a c i d w h i l e t h e a d v a n c e d s t a g e s i n t r o d u c e t h e a d d i t i v e
e f f e c t s o f u l t i m a t e d e g r a d a t i o n p r o d u c t s su ch as a l d e h y d e s , c e r t ­
a i n o f w h i c h c a n be d e t e c t e d c h e m i c a l l y .
Once i n c i p i e n t d e t e r i o r ­
a t io n s e t s i n , t h e o n s e t of t a i n t developm ent I n c r e a s e s r a p i d l y
s h ow i ng t h a t t h e p r o d u c t s ,
so much t h a t
as th e y form ,
cotnlyzo th e o x id a tio n
ev en t h e d i f f u s i o n o f v o l a t i l e p r o d u c t s from an ox­
id iz in g f a t can i n i t i a t e
o x i d a t i o n i n an a d j a c e n t sample of sweet
fat.
Po w ic k (.1923)
s t u d i e d numerous p o s s i b l e o l e i c a c i d d e ­
g r a d a t i o n p r o d u c t s , 7/ i t h r e s n e c t t o t h e i r r e s e m b l a n c e i n o d o r
to ran cid f a t .
r.in r e s u l t s n a y be s u m m a r i z e d a s f o l l o w s :
Tw enty-one known d e g r a d a t i o n
sponsible
for
the
f o l l o v ' i n g
n r r r e .
rancid
nroducis
odor.
of
oleic
scad were
"Tnese c o r . n o u r . d c a r c
given
not
re­
on n n c
59
3l y d r o x y s t e a r i c
acid
D ihydroxystearic
K eto stearic
acid
F orm aldehydo
acid
D ik eto stcaric
A sclaic
A c e t i c a.cid
A cetaldehyde
acid
Bu t y r a 1 d e 3ly d c
a. ci d
A crolein
H onylic a c id
C ro to n ic aldehyde
C aprylic
a . c id
L e t h y 1 y l y ox a 1
H eptylic
acid
Dihydroxy a c e to n e
C aproic acid
A crylic
B utyric
A z e l a i c h a l f alriehvdo
acid
acid
Form ic a c i d
I t vias f o u n d t h a t n o n y l i c a l d e h y d e p o s s i b l y c o n t r i b u t e s
some t o t h e r a n c i d o d o r v / h i l o h e p t y l i c
a l d e h y d e v;as l a r r o l y
rospon-
sible.
it
nay th u s
used asan in d e x
be c o n c l u d e d t h a t t h e
of ra n c id ity
o d o r o f a. f a t may be
o n l y so, f a r a s t h e p r o d u c t i o n o f h e p t -
aldehyde and p o s s i b l y n o n ald eh y d e a re concerned*
It
w i t h v ih ic h a
wr' s r e p o r t e d
f a t d e v e l o p s a r a n c i d o d o r e nd f l a v o r on o x i d a t i o n
seems t o be g r e a t e r ,
present*
a r e due t o
by B a r n i c o a t (19.11) t h a t t h e r e a d i n e s s
t h e s m a l l e r t h e am ount o f l i n o l e i c
He a l s o s t a t e d t h a t t h e
oleic
or l i n o l e n i c
ch aracteristic
acid
o d o r a nd t a s t o
a c i d doyrn U .tio n p r o d u c t s r a t h e r th a n l i n o l e i c
a c id products*
60
KREIS TEST:
A u se fu l co lo r t e s t ,
the K re is t e s t ,
od o f i n d i c a t i n g ; t h e p r e s e n c e o f a r a n c i d f o t .
is
a s e n s i t i v e m eth­
I t i s due t o th e
f o r m a t i o n o f a. c o m p l e x o f a f a t d e g r a d a t i o n p r o d u c t w i t h p h l o r o glucinol in a h y d ro c h lo ric
acid s o lu tio n .
t h a t o n ly compounds c o n t a i n i n g ; t h e a l l y l
a s u b s tit u te d a l l y l group
Robert
group
(1907)
concluded
( -CIIo-CH=0iI2 - )
or
( -CH2 -CH=CRR.' ) a r e c a p a b l e o f p r o d u c i n g
t h i s c o lo re d com plex.
Powick
(1923)
in a search f o r th e substance re sp o n sib le
f o r t h e c o l o r c o m p l e x f o u n d t h a t t w e n t y - s i x known o l e i c
g ra d a tio n p r o d u c ts gave n e g a tiv e K r e is t e s t s .
acid de­
A f t e r an e x t e n s i v e
e x a m i n a t i o n P o w io k f o u n d t h a t a c r o l e i n a n d h y d r o g e n p e r o x i d e p r o ­
du c ed a p o s i t i v e K r e i s t e s t w h i c h w a s s p e c t r o s c o p i c a l l y
w ith t h a t o b ta in e d from r a n c i d f a t s
and o x i d i z e d o l e i c
id en tical
acid.
The
f o l l o w i n g r e a c t i o n p r o d u c t s were s t u d i e d
i n o r d e r t o r.o c e r t a i n
the p o s s ib le
r e a c t i o n and t h e p h l o r o -
acro lein ,
hydrogen p e ro x id e
glucinol colored p ro d u c t:
61
II
lie - 0
+
2HoO
HCH
II
HC
I
CHO
HV
HC - 0
H - 0
H - 0
HCH- OH
I
HC - OH
I
Clio
HCH - OH
I
C = 0
I
HCH - DH
or
a cro lein
gly ceric
aldehyde
acro lein
peroxide
dihydroxy
acetone
0 = 0
H
0
HC
4-Ho 0
+
GIIc
I ~
C = 0
I
CHO
C = 0
I
HC = 0
or
m ethyl
glyoxal
m esityl
d iald eh y d e
CHO
i
HCI-I
I
CHO
HC
If
HC
or
OH
TIC
0
or
HC
I
CHO
I
I HO
m alonic
dialdehvde
oxacrolein
epihydrin*
aldehyde
E a c h o f t h e s e p r o d u c t s was s y n t h e s i z e d i n t u r n a n d t h e
color t e s t s
perform ed.
A l l gave n e g a t i v e t e s t s w i t h p h l o r o g l u c i n o l
w i t h t h e e x c e p t i o n o f e p i h y d r i n a l d e h y d e w h i c h was s y n t h e s i z e d as
follow s:
CH2=CHCIJ0
+
lie 1
+ 2C 23H5 OH
CHoC1CH2CH(0C2H5 ) 2
+
H2 0
( 3 - c h lo r -p ro p io n ic aldehyde d i —
eth y lacetal
KOH
CH2 OHCHC1CH(OC2H5 ) 2
H0C1
c^-c h lo r-|S -o x v -p ro p io n ic
CH2 = CHCM(0Ce II5 ) 2 + KC1 + H2 0
acro lein d ieth y lacetal
a l d e h y d e d i e t ’n y l a c e t a l
KOH
,
1
CII2bIIC H ( OC oH 5 ) 2
/°v
c h 2 chcho
+ KC1 + n 2 0
epihydrinaldehydo d io th y la c e ta l
HCl
e p ih y d rin aldehyde
Spihyclrin aldehyde i s very u n s ta b l e
iso la ted but i t s
d ir.c c talr, have been p r e p a r e d
and h a s n e v e r b e e n
as i n d i c a t e d .
This
m a t e r i a l w i l l p r o d u c e a r e d c o l o r w i t h p h l o r o g l u c i n o l e nd h y d r o ­
c h lo ric acid w hich s o e c tr o n c e p ic a l l y i s
I t v/as t h u s c o n c l u d e d t h a t
i t i o n of h y d r o c h l o r i c
phloroglucinol.
i d p n b i c ■.1 w i t h r a n c i d f a t .
e p ih y d rin aldehyde
acid to
its
i c f o r m e d by t h e a u d ­
d i a c e t - .1 and t h e n c o n d e n s e s w i t h
T h i n s u b s t a n c e may be p r e s e n t
an t h o g l y c e r y l
a c e ta l of e p ih y d rin aldehyde in the r a n c id f a t .
Kost s a t u r a t e d
a c i d s and a l d e h y d e s u p t o Cc, a r e n o t
responsible f o r tho Ilreis t e n t ,
t h e r e f o r e th e docoavposition of
o le ic a c id p e ro x id e m int p ro c e e d in p a r t
r o u t e tha.ii t h a t l o a d i n g t o t h e
at le a s t
by a d i f f e r e n t
f o r m a t i o n o f Co a c i d s
and a l d e h y d e s .
A l t h o u g h c o n t r a r y t o t h e u s u a l c o n c e p t s o r ., t ’ic c a r t o n c V . i n - a y
b r e a k a t a s a t u r a t e d bond i n p r o f e r one o t o t h e
d o u b l e b a n d s n a y f e r n w h i c h w i l l add ox.y pr.n.
t r i p l e peroxide
of l i n o l e n i c
d e co n p o sitio n nay y i e l d
lo n e r:
color i n t e n s i t y
sorption.
(iffA )
"J=0 a nd t hue i i ' u
The fori.:.-'1;i o n o f t h e
a c i d nay t h u s be p o s t u ’’ :.t e d v.diich an
e p ih y d rin aldehyde.
found t h a t o lo ic
a i t ’: t h e h r e i s
to s t for
a c id g iv e s th e yr-r t e s t
c..n e q u i v a l e n t oxy ge n a u -
V -o p r e s e n c e o f t ' - c a d d i t i o n a l f r e e
o leic
a c i d an a
f a t i n c r e a s e s t h e r -,t<? o f f o r m a t i o n o f c o n p o u n d s ce.us isa; t ic
to o t.
The d o c o a on:lxbion r r o d u c t c of o l e i c
are a c r y l i c , a c e tic
th e s e arc a ls o found in r a n c i d f a t s .
.
rcis
n.cicl e..ppe: .r no .;e x a -
o n t i c a l w it h. Pov.'iolc o c c r c l e i n - l i y c l r o n e n p e r o x i d e p r o d u c t .
decomposition, p r o d u c t s
j
a nd fo r m x c
.n rc lc in
OXIDATION OF L I H O T J B I C
AND LINOLENIC ACIDS;
In a s t - t a d y
o x i d a t i o n i s fourm_<=3_
-to
ifested in the
±ng
part these a c id s
^ o la y
(1934) s t a t e tha-fccontaining la rg e
he a c c o m p a n i e d by p o l y m e r i z a t i o n as i s man­
oils.
Disagreement occurs as t o th e a c t u a l
in ra n cid ity .
B a r n i c o a t (1931) and Ruemele
-fclie t e n d e n c y t o w a r d r a n c i d i t y i s g r e a t e r i n f a t s
a m o u n ts
of o le ic acid than in f a t s containing
<=>;T l i n o l e n i c and l i n o l e i c a c i d s as ju d g e d by odor
large q u a n t i t i e s
and t a s t e .
o f t h e a c i d 3 more u n s a t u r a t e d t h a n o l e i c ,
At hd_
- t e m p e r a t u r e s however t h e more h i g h l y u n s a t u r ­
ated a c id s o x i d i z
jra-pidly.
of t h e r a n c i d o d o n r —
and
In normal o x i d a t i o n th e i n t e n s i t y
t a s t e de p en d s upon t h e o l e i c a c i d p r e s e n t .
In d i s a s : x * e e m s n t w ith t h e s e r e s u l t s are the r e s u l t s of
o
Salway ( 1 9 1 6 ) .
r l ^
o x i d i z e d l i n s e e d o i l a t 100 and c o l l e c t e d t h e
ga seous p r o d u c t s
i n
believed l i n o l e n i - c r :
w ater.
The o d o r o f a c r o l e i n was n o t e d .
He
a c i d y i e l d e d a c r o l e i n o.c cording t o t h e f o l l o w ­
in g e q u a t i o n s :
RCH
II
CH
I
CH
II
CH
I
CH
RCH - 0
I
I
CH - 0
!
CH
II
CH
I
CH - 0
RCH
RCH - 0
He b e l i e v e d t h a t
J
I
& o r o le in
no t from o l e i c art ~
ri
or
RGHO
CHO
CJI
II ~
CH "
I
CHO
+
f(cho
f uraa r a j[^ e ’ny j e
(unstable)
CII2 = CMCHO + CO
COOH
CH
II
CH
I
CHO
-
CHP = CHCHO
+
CO:
c o u l d e l s e be formed from l i n o l e i c bui
glycerol.
The m i d d l e C = C g r o u p o f l i n o l e n i c
relativ ely
stab le.
The s t r u c t u r e
given f o r l i n o l e n i c
the a cc e p ted fo rm u la f o r e l e o s t e a r i c
contain th e
acid.
L inolenic
a c i d i s now
a c id does not
c o n j u g a t e d d o u b le bond s e r i e s .
Much o f t h e c o n t r o v e r s y i s
d ifficu lty
a c i d a p p e a r s t o be
p r o b a b l y d ue t o t h e e x t r e m e
i n p r e p a r i n g t h e s e a c id s i n p u re form .
Thus fro m a s t u d y o f t h e v a r i o u s p r o d u c t s , methods f o r
determ ining t h e i r r e l a t i v e
been d e v i s e d .
am ounts fo rm ed d u r i n g o x i d a t i o n have
The c o m p o s i t i o n a n d s t r u c t u r e o f t h e m a t e r i a l s com­
prising th e fre s h f a ts
and o i l s ,
a nd t h e c o n d i t i o n s u n d e r w h i c h
oxid atio n ta k e s p la c e c o n tro l th e changes t h a t
can be fo llo w e d
during th e p r o g r e s s i o n of r a n c i d i t y .
METHODS OF RECOGNIZING RAMCID FATS:
As a l r e a d y
stated ,
o r g a n o l e p t i c t e s t s were th e f i r s t to
be u s e d t o i n d i c a t e t h e p r e s e n c e o f r a n c i d f a t s .
no i n d i c a t i o n o f t h e
T h e s e methods gave
e x t e n t t o w h i c h o x i d a t i o n h a d p r o c e e d e d a nd
w ere t h u s o n l y a q u a l i t i a t i v e m e a . s u r e m e n t .
t i t a t i v e methods have b een d e v is e d t o
Many m o r e o r l e s s q u a n ­
i n d i c a t e t h e d e g re e to which
r a n c i d i t y h a s p r o g r e s s e d and t o f o l l o w t h e
course of th e re a c tio n
a f t e r o x id a tio n has been i n i t i a t e d .
It is
r e a d i l y n o t e d t h a t a £& e x p o s e d t o
o x id iz in g cond­
i t i o n s w i l l n o t be com e r a n c i d i m m e d i a t e l y b u t o n l y a f t e r a d e f i n i t e
period of tim e has e la p s e d .
T h i s p e r i o d o f t i m e i s known a s t h e
in d u ctio n p e rio d of the f a t .
explain t h i s
Numerous a t t e m p t s h a v e b e e n made t o
p e rio d of ap parent i n a c t i v i t y .
i t a s t h e t i m e r e q u i r e d by t h e
D avies
(1930) r e p o r t e d
system t o undergo a c t i v a t i o n , w h ile
M a t t i l l and Crav/ford (1 930)
i n d i c a t e d i t was a m e a s u re o f t h e p r o ­
o x id a n ts and a n t i o x i d a n t s a l r e a d y p r e s e n t i n t h e f a t .
to which t h e s e m a t e r i a l s
oxidation.
The e x t e n t
are p resen t c o n tro ls the re la tiv e
H i l d i c h and S le ig h th o lm e
(1932)
s ta te the
ease of
induction p e r­
i o d i s t h e i n t i a l p e r i o d o f r e s i s t a n c e o f t h e f a t t o a t t a c k by g a s ­
eous o x y g e n w h i l e B e t t e r
(1933)
expresses i t
a s b e i n g due t o t h e
union o f a n t i b o d i e s w i t h t h e a c c e l e r a t o r , t h u s p r o t e c t i n g t h e f a t
a g a i n s t oxygon a b s o r p t i o n .
The l e n g t h o f t h e
suscep tib ility
of the
and Rudy ( 1 9 3 3 ) ) .
through" a p a r t
fa t to
ind u ctio n p eriod is
oxidative ra n c id ity
( T r i e b o l d , Webb
When a f a t o n e x a m i n a t i o n h a s a l r e a d y
"lived
of th e i n d u c t i o n p e rio d or has been exposed d u r­
ing m a n u fa c tu re and s t o r a g e t o
pro-oxidants,
a good i n d e x o f t h e
its
c o n d itio n s fa v o rin g p ro d u c tio n of
s u s c e p tib ility to o xidation is p ro p o rtio n ally
i n c r e a s e d (Ivlatt.ill and C ra w fo rd ( 1 9 3 0 ) ) .
o th e r hand c o n t a i n a n t i o x i d a n t s ,
S h o u l d t h e f a t on t h e
th e se w i l l decrease the su sc e p t­
i b i l i t y t o o x i d a t i o n i n p r o p o r t i o n t o t h e i r e m ount a n d e f f e c t ­
iv en ess.
M a t t i l l and C r a w f o r d h a d a s s u m e d t h a t d u r i n g t h e i n d u c t ­
ion p e r i o d p e r o x i d i c compounds a c c u m u la te d i n amounts s u f f i c i e n t
to s t a r t i n t e r a c t i o n b e tw e e n u n s a t u r a t e d f a t s
oxygen.
and a t m o s p h e r i c
They l a t e r c h a n g e d t h i e r v i e w t o t h e p r e s e n c e o f a n a n t i -
o x id a tiv e power.
Holm a n d G r e e n b a n k c o n c l u d e d f r o m some e x p e r i m e n t s
t h a t t h e i n d u c t i o n p e r i o d w a s c a u s e d by t h e
of t h e n o n - f a t t y c o m p o n e n t s o f t h e
The l e n g t h o f t h e
nume rous f a c t o r s
an tio x id ativ e
action
o ils.
i n d u c t i o n p e r i o d may be i n f l u e n c e d by
s u ch as h e a t ,
lig h t,
im p u ritie s andm etallic c a t-
66
aly sts
(D avies (1930))„
antioxidants
U n d e r t h e i m p u r i t i e s may be c l a s s e d t h e
and p r o - o x i d a n t s w h i c h may b e d e r i v e d f r o m t h e n a t u r a l
o il or added s y n t h e t i c a l l y .
to a r is e
The n a t u r a l . a n t i o x i d a n t s a r e t h o u g h t
in th e u n s a p o n if ia b le p r o t i o n of th e f a t
(Yamaguchi ( 1 9 3 2 ) ) .
cussed.
etc.)
Th e s y n t h e t i c m a t e r i a l s h a v e a l r e a d y b e e n d i s ­
O t h e r i m p u r i t i e s may b e m o i s t u r e ,
m a t e r i a l s , w hich s h o r t e n th e
free acids,
induction period,
able of a d d in g energy t o th e system (D avies
O l c o t t and M a t t i l l
as l a r d ,
(stero ls,
have d e f i n i t e
(1936)
etc.
Those
a p p e a r t o be c a p ­
(1931)).
found t h a t anim al f a t s ,
such
i n d u c t i o n p e r i o d s f o l l o w e d by r a p i d o x y g e n
a b s o r p t i o n w h i l e v e g e t a b l e o i l s a b s o r b o x y g e n s l o v / l y a nd t h e
of t h e i n d u c t i o n p e r i o d i s
end
not sharp.
P u r i f i e d u n s a t u r a t e d compounds s u c h a s m e t h y l o l e a t e
appear to
h a v e no i n d u c t i o n p e r i o d o l h o r t h a n t h e t i n e
f o r g a se o u s oxygen t o d i f f u s e
cott (1936)).
R efined o i l s
in to the liq u id
required
( H a m i l t o n a nd O l ­
g iv e a s h o r t e r i n d u c t i o n p e r i o d which
may be d u e t o t h e r e m o v a l o f t h e n o n - s t e r o l u n s a p o n i f i a b l e s u b ­
s t a n c e s ]l a v i n g a n a n t i o x i d a t i v e
stero ls
( Royce ( 1 9 3 1 ) ) .
by s t e a m d i s t i l l a t i o n ,
5leis,M-k»ke,
d i t c h N(19 3 2 ) ) .
s t r e n g t h nrmy t i m e s t h a t
The i n d u c t i o n p e r i o d i s a l s o r e d u c e d
a l k a l i r e f i n i n g and e a r t h b l e a c h i n g ( h i l -
Gy g e n a b s o r p t i o n a f t e r t h e
iod i s
istic
innto
end o f t lie i n d u c t i o n p e r ­
r a p i d a nd g i v e s a l o g s . r i t h m e i i c c u r v e w h i c h i s
of a u to c a ta ly tic
p eriod th e
in h ib ito rs
of t h e
reactio n s.
are f i r s t
o x id atio n of th e f a t .
i s o v e r c o m e and t h e f a t
is
P ossibly
during th e
ch aracter­
induction
o x id is e d w hich d e la y s th e u l t -
In tim e th e
o x id ise d as i f
e f f e c t of t n e
no i . . o x f o r
ionic..":or
is
prcseno.
57
The c h e m i c a l a n d p h y s i c a l c o n s t a n t s d u r i n g - f c l i e i n d u c t i o n
period a p p ear to rem ain p r a c t i c a l l y c o n s t a n t .
At t h e
end
of th i s
p e rio d ra.pid c h an g es i n t h e s e c o n s t a n t s a r e n o t e d .
The i d e a l t e s t
(broadly defined)
is a m e a s u re
e r a g e r e s u l t s o f or.ch w e i g h t e d c h a n g e t h a t t a k e s p l a c e ,
ideal t e s t in a r e s t r i c t e d
w hile the
s e n s e would m easure o n ly t l o o s e
which c a u s e r a n c i d o d o r s a nd t a s t e s
is a l i s t
of t h e a v ­
(Pool (1 9 3 1 ) ).
T rio
substances
follow ing
o f t h e more commonly u s e d t e s t s :
Odor and T a s t e
Loss of C olor
Phy s i c a.l Co n s t a n t s
C h e r .' ic a l C o n s t a r t s
P e r o x i d e V a lu e
A l d e h y d e V a lu e
K reis Test
A c i d V o lu e
A c o t y l V a lu e
Sap o r : i f i c a t i o n Vri.lue
11o i c ' e r t - Kc i &s 1 V a l u e
I o d i n s Va 1u e
Promo. d e t e r m i n a t i o n
ofth e s e c o n s ta n ts th e c o n s t i t u t i o r .
f a t and i t s P t r e a t m e n t maybo d e t e r m i n e d ( i ’a t t i l l
a nd
ox t n e
Z r*w.wford
(,193u))
Odor and T a s t e :
I n c r e a s e s i n o d o r and t a s t o h a v e b e e n n o t e d
and u n d e r d a v l i g h t la mp s ( n a r n i c o a i ( 1 9 3 0 ) ) .
Javies
—rj s u n i i f > i i .id o l;
n ip
63
organoleptic t e s t s
a r e m o re d e l i c a t e
extent of th e r a n c i d i t y
Odor may
is
th a n chem ical t e s t s ,
but the
d i f f i c u l t to express q u a n tita tiv e ly .
be m a s k e d by t h e p r e s e n c e o f o t h e r o d o r i f e r o u s m a t e r i a l s .
O leic a c id in f a t s
and o i l s
a p p e a r s t o be t h e
main c o n ­
s t i t u e n t c o n c e r n e d i n t h e p r o d u c t i o n o f t a l l o w i n e s s a nd r a n c i d i t y
(Holm a.nd G r e e n b a n k ( 1 9 2 3 ) ) .
L i n o l e i c and r i c i n o l e i c
duce f a i n t t a l l o w y o d o r s e v e n wh en r e l a t i v e l y
ox yg e n h a v e b e e n a b s o r b e d .
acids pro­
l a r g e amounts of
L i n o l e n i c a c i d y i e l d s no t a l l o w y o d o r
on o x i d a t i o n (Holm a n d G r e e n b a n k ( 1 9 2 4 ) ) .
T a s t e a n d o d o r o f r a n c i d l a r d a r e n o t due t o t h e p r e ­
sence
of peroxides
( R o s c h e n a n d New to n ( 1 9 3 4 ) ) .
Loss o f C o l o r ;
T h i s h a s b e e n n o t e d w i t h o l i v e o i l by H o l l a n d ( 1 9 1 8 ) .
T h i s i s a p p a r e n t l y a s e c o n d a r y r e a c t i o n due t o t h e o x i d a t i o n o f
th e pigm ents i n th e f a t s .
Physical C onstants;
(Many o f t h e s e a r e n o t o f a n a l y t i c a l v a l u e ) .
R e f r a c tiv e Index i n c r e a s e s w ith o x id a tio n (H olland (19 1 8 ),
Spaeth
( 1 8 9 6 ) , S c a i a ( 1 8 9 7 ) , Browne ( 1 8 9 9 ) ) .
V i s c o s i t y i n c r e a s e s w i t h o x i d a t i o n ( H o lla n d ( 1 9 1 8 ) , K e rr (1923)
a nd S o r b e r ) .
M elting p o i n t i n c r e a s e s w i t h o x id a t i o n (H olland (1 9 1 8 ), Spaeth
(1896)).
Heat o f C o m b u stio n d e c r o a s e s i n i n v e r s e r a t i o
specific
g rav ity
to th e in c re a s e in
( L a n g b e e n a n d S t a h l m a n ( 1 8 9 0 ) , Browne ( 1 8 9 9 ) ) .
69
S pecific G rav ity in c r e a s e s
on o x i d a t i o n ( B a l l a n t y n e
(1891), F ahrion
( 1 8 9 3 ) , S c a l a ( 1 8 9 V ) , Brovme ( 1 8 9 9 ) ) .
C onstant in c r e a se s
D ielectric
on o x i d a t i o n i n l i g h t a n d i n m o i s t u r e
(Brovme ( 1 8 9 9 ) ) .
Peroxide V a lu e :
F ats
low er
active
exposed t o
o x id iz in g c o n d itio n s i n s u n l i g h t give
o x y g e n v a l u e s t h a n w h e n t h e same f a t i s
d a y l i g h t la m p a c c o r d i n g t o B a r n i c o a t ( 1 9 3 0 ) .
(1931)).
i s no a b s o l u t e p a r a l l e l i s m
A lthough
betw een p e r o x i d e number, a deg­
re e o f r a n c i d i t y due t o t h e i n f l u e n c e
type of f a t
(Lea
o f p e r o x i d e s a r e f o r m e d d e p e n d i n g on t h e
t e m p e r a t u r e o f o x i d a t i o n ( T a f f e l a nd R e v i s ( 1 9 3 1 ) ) .
th e re
As o x y g e n
th e peroxide value i s ap t to f lu c tu a te
D iffe re n t ty p es
a
H a r d f a t s be come
ra n c id a t lo w e r a c t i v e oxygen v a lu e th a n s o f t o n e s.
absorption in c r e a s e s ,
exposed to
of
h e a t a n d l i g h t e-nd t h e
on t h e amount o f p e r o x i d e s fo rm e d , t h i s t e s t
is
at
p r e s e n t t h e b e s t kn ow n f o r f o l l o w i n g t h e p r o g r e s s o f r a n c i d i t y
in f a ts
(B r o w n e
(1899)).
Aldehyde V a lu e :
A ldehydes i n c r e a s e d u rin g o x id a tio n (H olland (1 9 1 8 )).
I t has b e en fo u n d t h a t h e p t y l i c
ib le for th e
r a n c i d od.or a n d t a s t e
to a fresh f a t ,
a r e noted
a n d noiyLic a l d e h y d e s a r e r e s p o n s ­
conditions
of a f a t .
Y?hen t h e s e a r e a d d e d
s i m i l a r t o t a l l o w i n e s s and r a n c i d i t y
(H olm a n d G r e e n b a n k
(1923)).
K reis T e st:
This i s
the
c o l o r r e a c t i o n c a u s e d by t h e u n i o n o f
70
p h l o r o g l u c i n o l and e p i h y d r i n a ld e h y d e .
Its
d e te c tio n of r a n c i d i t y has been e x te n s iv e ly
concluded t h a t a l l r a n c i d f a t s
r e l a t i o n s h i p to the
stu d ied .
reacted to the t e s t
K e rr (1918)
and th e c o lo r
i n t e n s i t y w as r o u g h l y p r o p o r t i o n a l t o t h e d e g r e e o f r a n c i d i t y .
Fresh f a t s w ith th e e x c e p tio n o f c o tto n s e e d o i l
negative c o lo r r e a c t i o n .
delicate
The t e s t
alw ays give a
(a.ccording t o Ilin c k e l)
s i n c e o t h e r a l d e h y d e s , k e t o n e s and e s s e n t i a l
to th e t e s t .
back a s i t
This s e n s i t i v i t y
need n o t n e c e s s a r i l y
is too
oils react
be a draw­
c a n be u s e d a s a w a r n i n g o f i m p e n d i n g r a n c i d i t y
(K err
S a t u r a t e d a l d e h y d e s do n o t r e a c t t o t h e K r e i s t e s t
)) w h i l e
very r a p i d l y .
lin o len ic
c r o t o n i c ald eh y de give
U nsaturated acid s
such as o l e i c a c i d ,
a c id s give o p o s i t i v e t e s t
.nd G r e e n b a n k
(P o-
( 1 9 .1 4 ) )
3mao c o l o r s h a d e r
L inoleic
o leic
lin o leic,
on a b s o r p t i o n o f oxyg e n (Holm
and l i n o l o n i c
acid
acid
. f t e r l a r d and
olrn a n d G r e e n b a n k ( 1 9 1 3 ) f o u n d
b u t t o r f a t h a v e a b s o r b e d a c e r t a i n v o lu m e o f o x y g e n , t h o l a r d
give
ently to the
relativ e
q u an tities
of u n s a tu r a te d
the K re is t o s t
A com parison of v a rio u s to
I.
fJ o l o r n r o d u c t i o a i
zl
r
ith
the Kreis t e s t
giv
71
of o x y g e n a b s o r b e d
(K e rr (1913)
Oleic a c i d g iv o s t h e
a n d Holm and G r e e n b a n k
(19.11)).
g r e a t e s t c o l o r i n t e n s i t y f o r an e q u i v a l e n t
oxy ge n a b s o r p t i o n .
R a n c id ity as d e te rm in e d o l f a c t o r i l y
to th e c o lo r i n t e n s i t y
(V /inckel,
a l s o shows no s u c h r e l a t i o n s h i p
is
not p ro p o r tio n a l
and K e r r (.1 9 1 3 )).
T allow iness
( Holm a n d C r e e n b a n k ( 1 9 2 3 ) ) .
Peroxide p ro d u c tio n v a r ie s w ith the c o n d itio n s
a tio n according to B nrnicoat
a high p e ro x id e v a lu e i s
ect p a r a l l e l i s m
(1931) w h ile T h e c l o r (1932)
of o x id ­
found
a c c o m p a n i e d by a h i g h K r c i s t e s t .
of t h e lire i s t e n t i n t e n s i t y w i t h a c t i v e
A d ir­
oxygen has
b e e n r e p o r t e d w h i l e a w i d e v a r i a t i o n b e t w e e n t h e s e tw o h a s a l s o
boon o b s e r v e d .
Acid V a l u e : '
As s t a t e d b e f o r e ,
onomous w i t h r a n c i d i t y
i t w a s b e l i e v e d t h a t a c i d i t y w.as s y n -
and a s a r e s u l t th e f r e e
f a t was u s e d a s a n i n d e x o f r a n c i d i t y .
disproved.
a c id c o n te n t of a
T h i s r e l a t i o n s h i p Iv s b e e n
I ' e r r and 3 o r b e r ( 1 9 2 3 ) f o u n d t h e a c i d v a l u e o f a f a t
i n c r e a s e d on. e x p o s u r e , t h e n d e c r e a s e d when t h e p h y s i c a l s i g n s o f
r a n c id ity appeared a n ’ f a m i l y
the a c id v a lu e i s
hydrolysis
a n i n c r e a s e v." s o b t a i n e d ,
n o t a good i n d e x o f r a n c i d i t y
of a f a t w ill
T :us
(.dtokoe ( 1 9 2 1 ) ) .
c a u s a an i n c r e a s e i n i t s
a cid value
( P o o l (19 3 1 ) ) .
A cetyl V alue:
This is
an i n d i c a t i o n o f t h e h y d r o x y l g r o u p s p r e s e n t .
A c c o r d i n g t o h r o ’wnc ( i d ' T f ) t h e r e
is
an i n c r e a s e
on o x i d a t i o n .
S a p o n if ic a tio n V alue:
D uring o x id a tio n i t
ber (w hich i s
is
f o u n d t h a t t h e s a p o n i f i c a t i o n num­
a m e a s u r e o f t h o me an m o l e c u l a r w e i g h t o f t h e f a t t y
acids p re s e n t)
i n c r e a s e s due t o t h e f o r m a t i o n o f a c i d s o f l o w e r m o l e ­
cular w eight.
The i n c r e a s e i s
n o t n e c e s s a r i l y c o n s t a n t and t h u s
t h i s v a lu e c an n o t be u sed t o d e te r m in e t h e e x t e n t of r a n c i d i t y
(Browne ( 1 8 9 9 ) ) .
R e ic h e rt-ld e is s l V alue:
This i s
a d e term in a tio n of the v o l a t i l e
soluble f a t t y
a c i d s , w h i c h a r e f o u n d t o i n c r e a s e on o x i d a t i o n o f t h e f a t
(Browne
(1899)).
I o d i n e Vurnb e r :
T his i s
Then oxygen i s
s. m e a s u r e o f t h e u n s a t u r a t e d b o n d s i n a f a t .
ab so rb ed , th e value w ill decrease
( H o l l a n d (191'-.))
but n o t enough t o w a r r a n t i t s
use as an in d e x of r a n c i d i t y
(1899)).
It
enough to d e t e c t sm all changes th ro u g h
oxidation
(Holm a n d G r e e n b a n k
is
not s e n s itiv e
(Brcvnc
(1923)).
U nsaponifiable H a tte r:
T h is has been found to
ran cid ity
(Pool
(1931)).
i n c r e a s e w ith th e p ro d u c tio n of
73
C om position o f f a t s
and o i l s :
Table I I I
T y p ic a l a n a l y s e s o f t h e f a t t y a c id s i n v a r i o u s f a t s and o i l s
1
Lard
B u tterfat
B utyric
4 .3
C aproic
1-6
C aprylic
1.2
C arpic
1.2
L aurie
5.0
S tearic
C risco
L inoleinic
E rucic
0.4
32
14.8
6-10
20
8
3.4
2r- 3
2
0.2
S aturated
L inoleic
2
2
;
O live C ottonseed L inseed
trace
A rachidic
O leic
3
16.4
liy r is t ic
P alm itic
1
60
44 .8
0.4
0.7
6 -1 1
30-40
14-15
23
50-65
75-85
29-34
5
5-12
4-12
3 9 -4 3
48.5
20-34
*'
n
JL* I
1 F a t s a n d W a x e s , H i l d i t c h ( 1 9 2 7 ) Van M o s t r a n d
2
J a m i s o n , F a t s a n d O i l s , A. C , S . M on og ra ph
STATEMENT OF PROBLEM
T h i s r e s e a r c h work was u n d e r ta lc e n f o r t h e p u r p o s e o f
obtaining a b e t t e r u n d e rstan d in g of th e o x id a tio n of f a t s
and t h e c o n d i t i o n s w h i c h c o n t r o l t h i s
and o i l s
reactio n ,
EXPERIMENTAL
D escription of th e A pparatus:
The a p p a r a t u s u s e d t o d e t e r m i n e t h e i n d u c t i o n p e r i o d a n d
the r a t e s
o f oxygen a b s o r p t i o n o f f a t s and o i l s d u r in g o x i d a t i o n
was d e s i g n e d a n d c o n s t r u c t e d by M, H, M e n a k o r ,
The e s s e n t i a l p a r t s
of th e machine in c lu d e a t h e r m o s t a t i c a l l y c o n t r o l l e d
fo rce d c i r c u l a t i o n and a s p e c i a l l y
s i s t i n g o f an oxygen r e s e r v o i r ,
a i r oven w ith
designed a b s o r p tio n system con­
a r e a c t i o n chamber, and a p r e s s u r e
control d ev ise.
D uring each o x i d a t i o n experim ent a co n tin u o u s autom atic
record of th e
oxygen a b s o r p t i o n i s
obtained.
T h is oxygen a b s o r p -
t i o n t a k e s p l a c e i n t h e r e a c t i o n chamber a t c o n s t a n t p r e s s u r e i r r ­
esp ectiv e of v a r i a t i o n in atm ospheric p re s s u re .
The l i t e r a t u r e
c o n t a i n s numerous r e p o r t s o f methods p r o ­
posed f o r m e a s u rin g t h e i n d u c t i o n p e r io d of f a t s .
Most o f t h e s e
r e q u i r e a l o n g p e r i o d o f tim e a s t h e y must be c a r r i e d out a t r e ­
lativ ely
low t e m p e r a t u r e s o r t h e y n e c e s s i t a t e tlie c o n t i n u a l p r e s ­
ence of t h e
i n v e s t i g a t o r th ro u g h o u t th e experim ent p a r t i c u l a r i t y
i f th e change in oxygen a b s o r p t i o n w ith tim e i s
o b j e c t i o n s a r e overcome i n t h i s
The a p p a r a t u s c o n s i s t s
d esired .
These
apparatus.
o f a g r o u p o f u n i t s w h i c h may oe
75
described as fo llo w s :
C o n s t a n t T e m p e r a t u r e O ve n:
The o v en u s e d i n t h i s
set-up is
a D e s p a t c h B a k i n g Oven
m o d i f i e d by t h e i n t r o d u c t i o n o f a c i r c u l a t i n g f a n a n d a t h e r m o ­
s t a t to m a in ta in consta.nt te m p e r a tu r e .
The f a n was b u i l t i n t o t h e
o v e n a s shown i n F i g . 1 a nd
b a f f l e s w ere p l a c e d so t h a t a i r i s
dr aw n a c r o s s t h e h e a t e r s i n t h e
b o t t o m ox t h e
sample and r e t u r n e d t o t h e
heaters.
o v e n , blown p a s t t h e
Th e f a n i s d r i v e n by 8. p u l l e y c o n n e c t e d w i t h a 1 / 4 h o r s e ­
power m o to r i n one t o f o u r r a t i o
so t h a t i t
r o t a t e s a t a b o u t 430
r.p.m .
The t h e r m o s t a t i s o f t h e
type.
I t c o n tro ls the
f a m i l i a r m ercury over to lu e n e
s i x v o l t D. C. l i n e t o
a n Aminco s u p e r s e n ­
s i t i v e m e r c u r y make a n d b r e s . k r e l a y w h i c h i n t u r n c o n t r o l s t h e 110
v o lt lin e to
a s o le n o id type r e l a y .
an d b r e a k i n t h e
220 v o l t
circu it
The l a t t e r a c t s a s t h e make
feeding th e h o a te rs.
Pressure R eg u lato rs:
The c o n s t r u c t i o n o f t h i s
draw ing, F i g .
unit is
a p p a r e n t from th e
2.
P re s su re C o n tr o l V alve:
T his u n it i s
designed to
oxygen r e s e r v o i r i n t o t h e
a llo w oxygen t o flo w from an
a b s o r p t i o n system u n d e r th e i n f l u e n c e
o f th o p r e s s u r e r e g u l a t o r w i t h o u t a l l o w i n g any lo c k a g e e i t h e r
from or t o t h e
a .la rg o t i r o
su rro u n d in g atm osphere.
valve
such a s i s used
It
is
c o n s t r u c t e d from
in a tru cx t i r e ,
a. l a r g e e . l o c u -
3A
0 1 2 3 4
i n c h e s
M * r( u r y
F ig u r e 1 .
O x i d a t i o n A b s o r p t i o n A p p a r a tu s
77
Rubber
Platinum
Mercury
O
2
INCHES
F ig u re 2 .
P r e ss u r e R e g u la to r
7S
ro ms -g ne i,
etc.
The d e t a i l s
of c o n s tr u c tio n are f u l l y
described in
Fig. 3.
Oxygen R e s e r v o i r a n d R e c o r d i n g A p p a r a t u s :
The u n i t i s
rep resen ted
i n R ig . 1 and c o n s i s t s o f a F l o r ­
en ce f l a s k w i t h a s i d e a r m a n d a t u b e e x t e n d i n g t h r o u g h t h o n e c k
to th e bottom of th e f l a s k .
Pyrex t e s t tu b e
This tu b e i s
s e a l e d t o a 25 x 300 mm.
i n w hich th e re c o r d in g f l o a t
o p erates.
The l a t t e r
c a r r i e s a l e n g t h o f 5 mm. P y r e x r o d t o w h i c h t h e r e c o r d i n g p e n i s
attached.
The r o t a t i n g d ru m i s a c a n c o n t a i n i n g a c l o c k w o r k m e c h ­
anism i n s t a l l e d
12 h o u r s .
so as t o
When i n u s e ,
produce a com plete r o t a t i o n
of t h e can i n
a p i e c e o f g r a p h p a p e r (X/2C i n . )
i s wrapped
on t h e c a n a n d h e l d i n p l a c e w i t h gummed l a b e l s o r S c o t c h t a p e .
A b s o r p t i o n Chamber:
The c o n s t r u c t i o n o f t h i s
a l l y o f e 250 c c . f l a s k
j o i n t t o w hich t h e r e
shown c l e a r l y
u n i t , w hich c o n s i s t s fundam ent­
f i t t e d w i t h a m a le end c f a s t a n d a r d t a p e r
c a n be a t t a c h e d a w a s h b o t t l e f i t t i n g ,
in F ig.
i s " 'i s o
1.
F ig . 4 i s th e w irin g diagram shoving th e e l e c t r i c a l
circu it
req u ired .
0PRRATI0U OF T'!E APPARATUS;
The o v e n i s
of th e t h e r m o s t a t i c
adjusted to
control..
the
d e s i r e d
t e m p e r a t u r e bv means
79
(D
id
CMoH
z
F i g u r e 3«
P r e s s u r e C o n t r o l V a lv e
F ig u re
IIOV. A.C.
4,
To M o to r
W iring
Diagram
Pressure Regulator
9 0 V DC.
of
Solenoid Relay
the
E le c tr ic a l
Telegraph
Relay
'-----------------
6V EC’
C ir c u it
p W A W v V W \W W W \A A
Heaters
m Oven
*
Rectifying
Ci r c u i t n o t S h o w n
CD
A sam ple of f a t
i s w e ig h e d i n t o t h e a b s o r p t i o n chamber
and t h e a b s o r p t i o n s y s t e m i s
Stopcock number 2 i s
i t ion A (F in .
5).
t h e oven and t h e
a s s e m b l e d v / i t h s t o p c o c k n um be r 1 o p e n .
o p e n e d a n d s t o p c o c k nu mb er 3 i s t u r n e d t o n o s ­
The a b s o r p t i o n c h a m b e r ( F i g * 1 ) i s
r u b b e r tu b e from t h e p r e s s u r e c o n t r o l system i s
a tta c h e d t o t h e tu b e w h ich p r o j e c t s from th e oven.
t r o d u c e d t h r o u g h s t o p c o c k n u m b e r 2 and a l l o w e d t o
s y s te m f o r a for; m i n u t e s .
pressure
s t o p c o c k n um be r 2 i s
introduced
T he n s t o p c o c k n u m b e r 2 i s
s t o p c o c k nu m b o r 2 i s o pe ned
i n t o th o oxygen r e s e r v o i r t h r o u g h s t o p ­
i s a d v i s a b l e to f l u s h t h e a b s o r p t i o n system
i n g drum c a r r y i n g a s h e e t
in th e
Stopcock number 3 i s
1 is
opened.
open ed
S t o p c o c k number 3
v/ith oxygen s e v e r a l t i m e s b e f o r e f i n a l l y f i l l i n g i t .
and t h e p r e s s u r e
allo w tho
o p e n e d a t i n t e r v a l s u n t i l no f u r t h e r c h a n g e
p o s itio n B (F ig. 5),
cock number 2 - i t
s t o p p e d a nd s t o p ­
In o rd e r to
m o m e n t a r i l y w h i l e s t o p c o c k n u m b e r 4- i s c l o s e d .
and o x y g e n i s
flow th ro u g h th e
e q u ilib riu m a t atm ospheric p re s s u re ,
i s a p p a re n t i n t h e m anom eter.
i s now t u r n e d t o
n itro g en is i n ­
The f l o w o f n i t r o g e n i s
c o c k s numb er on e a n d n u m b e r tw o a r e c l o s e d .
system to a t t a i n
in s e rte d into
The r e c o r d ­
o f g r a p h p a p e r i s now p u t i n t o p o s i t i o n
ox y g en r e s e r v o i r i s r e a d fro m t h e monometer.
now t u r n e d t o p o s i t i o n A and s t o p c o c k number
O xygen i s
i n t r o d u c e d a g a i n t h r o u g h s t o p c o c k number 2
and a l l o w e d t o f l u s h a l l t h e n i t r o g e n o u t o f t h e a b s o r p t i o n c h a m b e r .
The a r m a t u r e on t h e t e l e g r a p h i c r e l a y i s p u l l e d o v e r t o a l l o w t h e
re c o rd in g pen t o
records th e s t a r t
d r o p s l i g h t l y when t h e o x y g e n f l o w i s s t a r t e d .
This
of th e ru n .
A f t e r two o r t h r e e m in u te s t h e f lo w o f oxygen i s
stopped
82
^
'r
Position A
P e r il i o n
F ig u r e
5.
B
P o s i t i o n o f S to p c o ck s i n Oxygen
A b so r p tio n A pparatus
and s t o p c o c k s n u m b e r on e a n d n um be r t w o c l o s e d .
a l l o w e d t o come t o
The s y s t e m i s
e q u i l i b r i u m and t h e n s l i g h t s u c t i o n i s a p p l i e d
th ro u g h s to p c o c k number 2 u n t i l t h e p r e s s u r e c o n t r o l a p p a r a t u s i s
activated.
The s t o p c o c k n u m b e r 2 i s
control valve i s
open -
t h i s valve
clo sed w hile th o p re ssu re
s h o u l d now c l o s e a u t o m a t i c a l l y
a f t e r a few s e c o n d s .
In g e n e ra l i t
15 m i n u t e s a f t e r t h i s
i s b e s t t o o b s e r v e t h e m a n o m e t e r f o r 10 t o
last
o p e r a t i o n i n o r d e r t o be c e r t a i n o f p r e s
u r e a nd t e m p e r a t u r e e q u i l i b r i u m .
in terv al,
s t o p c o c k number 3 i s
ic a lly record th e
I f no c h a n g e i s
noted a f t e r t h i s
c l o s e d and t h e s y s t e m w i l l a u t o m a t ­
oxygen a b s o r p t i o n .
I f tho p re ssu re in th e
a b s o r p tio n system changes,
suction
i s a p p l i e d a s b e f o r e and t h e p r o c e d u r e i s r e p e a t e d from t h a t p o iz it.
As t h e o x y g e n a b s o r p t i o n p r o c e e d s a nd g a s i s t a k e n up by
th e sam ple, t h e p r e s s u r e i n th e a b s o r p tio n system i s
ing th e m ercury l e v e l s
lowered c a u s ­
i n t h e p r e s s t i r e c o n t r o l l e r t o be s h i f t e d s o
t h a t th e e l e c t r i c a l c i r c u i t i s com pleted th ro u g h t h e te le g r a p h ic
r e la y w hich t h e n a c t u a t e s t h e
solenoid v alv e.
The o p e n i n g o f t h i s
valve allo w s oxygen t o flow from th e r e s e r v o i r i n t o th e a b s o r p tio n
system u n t i l t h e p r e s s u r e
in th e
l a t t e r retu rn s to
its
original
c o n d i t i o n a t w h i c h t i m e t h e p r e s s u r e c o n t r o l l e r c i r c u i t op e ns rg o .i n
and t h e o x y g e n f l o w i s
As g a s i s
cut o ff.
r e m o v e d i n t h i s way f r o m t h e r e s e r v o i r it. I s
r e p l a c e d by m e r c u r y f r o m t h e t u b e c u r r y i n g t h e r e c o r d i n g i l o u t , .
This a llo w s t h e
flo a t to f a l l
slig h tly
and t h u s c a u s e s t h e p e n t o
i n d i c a t e a d r o p on t h e c h a r t c a r r i e d by t h e r o t a t i n g drum.
84
A fte r com pletion of a d e te rm in a tio n th e
gen w h i c h h a d b e e n a b s o r b e d a t t h o e n d o f any t i n e
t h o r u n may b e c a l c u l a t e d .
q u a n t i t y of oxy­
i n t e r v a l during
(R eference - Report given a t C in c in n a ti,
Ohio m e e t i n g o f t h e A m e r i c a n C h e m i c a l S o c i e t y - t o bo p u b l i s h e d ) .
In a l l d e t e r m i n a t i o n s i n which t h i s
a p p a r a t u s was u s e d ,
a t e n gram s a m p l e was u s e d .
TEMPERATURE STUDY:
A study of th e
e f f e c t o f t e m p e r a t u r e o f t h e o x i d a t i o n on
t h o i n d u c t i o n p e r i o d w as made on a s cr ap ie 01 o p e n - k e t t l e r e n d e r e d
l a r d purchased, a t a l o c a l m a r k e t.
The l a r d was a l l o w e d t o m o l t a t
a low t e m p e r a t u r e a n d u n i f o r m s a m p l e s w e r e w e i g h e d i n t o t h o a b s o r p ­
tio n fla s k s .
In o rd e r to m a in ta in i d e n t i c a l c o n d itio n s a l l
sa.mnlos
w e re a l l o w e d t o s o l i d i f y i n t h e i c e c h e s t b e f o r e r u n n i n g .
l i a b l e IV g i v e s t h o r e s u l t s
o b t a i n e d on t h o i n d u c t i o n p e r ­
i o d .at v a r i o u s t e m p e r a t u r e s .
T a b l e IV
V a ria tio n of th e
T em perature
D egrees C
In d u c tio n P eriod
In d u c tio n P eriod
m inutes
70
of h a r d w i t h T e m p e r a t u r e
Average
1535
1535
80
636
90
335.9 -3 4 6 .6
r, o .
100
1 38.3-138.7
138.6
110
180
—
67 .3 -
;1 V a r i a t i o n
666
69.9
651
A
A
0.1
85
A r a t h e r high d egree
of accuracy is p o ssib le w ith th e apparatus
as i s
c h e c k s o b t a i n e d on d u p l i c a t e r u n s .
e v i d e n t by t h e
F ig,
6 illu stra te s
te m p e ra tu re and t h e
th e le n g th of’ t h e
g r a p h i c a l l y t h e r e l a t i o n betw een
l o g o f t h e i n d u c t i o n p e r i o d and i n d i c a t e s t h a t
i n d u c t i o n p e r i o d i s ' d e c r e a s e d by a p p r o x i m a t e l y
o n e -h a lf f o r each nine degree in c re a s e in te m p e ra tu re .
Since th e r e
degree r i s e
is th is
in tem peratu re,
d e f i n i t e r e l a t i o n s h i p f o r each nine
e.s w i t h a l l c h e m i c a l r e a c t i o n s ,
it
would i n d i c a t e t h a t a c h e m i c a l r e a c t i o n t a k e s p l a c e d u r i n g t h e i n d ­
u ction p eriod.
Sim ple d i f f u s i o n of oxygen i n t o th e f a t
f i c i e n t to e x p la in t h i s
resu lts
p e rio d of apparent i n a c t i v i t y .
is
net su f­
Those
o b t a i n e d w ould te n d t o i n d i c a t e t h e r e f o r e t h a t t h e r e a c t i o n
in v o lv e s th e a n t io x id a n ts i n th e
l a r d o r t h e b u i l d i n g up o f a
high o x id a tio n p o t e n t i a l ,
PRESSURE STUDY;
An a t t e m p t w as made t o
sure during th e
s t u d y t h e e f f e c t p r o d u c e d by p r e s ­
o x i d a t i o n o f a sample o f l a r d .
i n g 10 g ra m s o f o p e n - k e t t l e
Each e x p e r im e n t u s ­
r e n d e r e d l a r d was c a r r i e d o u t i n t h e
c u s t o m a r y m a n n e r by f i l l i n g t h o a b s o r p t i o n c h a m b e r a nd t h e r e s e r v o i r
w i th oxygen,
E x c e s s o x y g e n was t h e n a d m i t t e d i n t o t h e a b s o r p t i o n
f l a s k u n t i l t h e manometer i n d i c a t e d t h e d e s i r e d p r e s s u r e r e a d i n g .
The p r e s s u r e
r e g u l a t o r was s e t f o r t h i s v a l u e so t h a t t h o p r e s s u r e
w ould rem ain c o n s t a n t d u r i n g t h e r u n .
p r e s s u r e s above a tm o sp h eric p r e s s u r e ,
since the
system .
The e x p e r i m e n t s i n v o l v i n g
however, were u n s a t i s f a c t o r y
s y s t e m w o u l d n o t h o l d t h e i n c r e a s e d p r e s s u r e w i t h i n tri e
86
10,000
Induction
Period
(minutes)
1000
100
%
70
S O
90
Tem perature
Figure i.
100
C
Relationship
©'tween Temperature a n d
of the I n d taction Period of Lard
P r e s s u r e s l o w e r t h a n a t m o s p h e r i c w e r e o b t a i n e d by e v a c ­
uating th e
om eter,
s y s t e m t o t h e d e s i r e d p r e s s u r e a s i n d i c a t e d by t h e man­
The p r e s s u r e r e g u l a t o r w a s t h e n a d j u s t e d t o t h i s v a l u e .
Only one s a t i s f a c t o r y p r e s s u r e r e a d i n g w a s o b t a i n e d .
B el o w t h i s
th e system w ould n o t r e t a i n t h i s p r e s s u r e .
The r e s u l t s
o b t a i n e d a r e i n d i c a t e d i n T a b l e V.
Table V
V a ria tio n of the
In d u c tio n P erio d of £ard w ith P ressu re
Pressure
In d u c tio n Period
736 mm
1 3 8 ,7 inin.
732 mm
138.5 min.
729 mm
13 9 .2 m in.
52 7 mm
1 3 8 .3 m in.
6 27 mm
1 4 3 .5 m in.
I t may b e c o n c l u d e d t h a t o v e r t h e r a n g e o f 100 mm ( a p p r o x o f (ke 'in d u c tio n
im ate) d i f f e r e n c e
i n p r e s s u r e a ny c h a n g e I n t h e l e n g t h e n i n g ^ p e r i o d
is w ith in experim ental e r r o r .
I t w ould seem r e a s o n a b l e t o e x p e c t
t h a t v a r i a t i o n s i n p r e s s u r e would a f f e c t t h e i n d u c t i o n p e r i o d o n ly
i n so f a r a s t h e p r e s s u r e
in th e l a r d .
c o n t r o l s t h e amount o f o x y g e n d i s s o l v e d
A d i f f e r e n c e I n p r e s s u r e o f 100 mm i s
s u f f i c i e n t t o p r o d u c e any n o t i c e a b l e
induction p e rio d .
change in th e
a p p a re n tly not
l e n g t h of t h e
EFFECT OF ACIDS:
As h a s b e e n s t a t e d
i n th e h i s t o r i c a l s e c t io n of t h i s
t h e s i s , no d e f i n i t e c o n c l u s i o n s h a v e b e e n a r r i v e d a t r e l a t i v e t o
the ro le t h a t f r e e f a t t y
t o be o x i d i z e d .
a c i d s p l a y w he n a d d e d t o a f a t w h i c h i s
A c e r t a i n a c i d may a c t a s a p o s i t i v e c a t a l y s t
t o one f a t a n d a n e g a t i v e c a t a l y s t s t o a n o t h e r f a t .
m olecular ?/eight of th e
added a c id 3 has been r e p o r te d as f a v o r in g
the in c re ase d o x id a tio n of a f a t .
does not a p p e a r c o n c l u s i v e a s t h e
same h o m o l o g o u s s e r i e s .
Increased
The e v i d e n c e o f f e r e d , h o w e v e r ,
a c i d s compared were n o t of t h e
Furtherm ore th e s e
i n v e s t i g a t o r s compared
a c i d s on t h e b a s i s o f w e i g h t p e r c e n t s w h i c h o f f e r s no b a s i s f o r
c o m p a r i s o n a s t h e r e w o u l d be w i t h m o l e c u l a r p r o p o r t i o n s .
Procodure:
I d e a l c o n d i t i o n s f o r com paring t h e e f f e c t s
fatty
a c id s w ould in c lu d e d t h e u se o f a p u re o x id i z a b l e f a t t y
su b sta n c e as th e
pare
of v ario u s
su b strate.
V a r i o u s a t t e m p t s w e r e made t o p r e ­
o l e i c a c i d by d i s t i l l a t i o n
lead s a l t b u t an a cid of the
o f t h e m e t h y l e s t e r and a s t h e
desired p u rity
could, n o t b e o b t a i n e d .
I n s t e a d l a r d w i t h a n i n d u c t i o n p e r i o d o f c o n v e n i e n t l e n g t h was
chosen as a re a d y o x id iz a b le
An o p e n - k e t t l e
fatty
su b strate.
r e n d e r e d l a r d was m e l t e d a t a low t e m p ­
e r a t u r e and s a t u r a t e d f a t t y
acids
o f e v e n c a r b o n c o n t e n t wore
a d d e d i n 0 . 0 3 4 1 ?.! q u a n t i t i e s t o u n i f o r m s a m p l e s o f t h i s
T his w e ig h t was s e l e c t e d
approxim ately t h i s
since previous
a c i d c o n c e n t r ' -t i o n .
lard.
i n v e s t i g a t o r s had u s e d
The
saturated
a c i '.s
were v / e i g h e d i n t o
large
test
the sa m p les were s t o r e d a t
Before t h e
in d u ction
vms a g a i n m e l t e d
tion f l a s k .
perim ents,
and t e n
refrig era tio n
o f e a c h sam ple was d eterm in e d t h e f a t
g r a m
sam ples in th e
s pinole a
w a r e
w eighed in t o t h e
o f one s a m p l e ,
out
as p r e v i o u s l y d e s c r ib e d .
the e x ­
the la r d w ere checked w ith r e s p e c t t o
Oxid­
Upon c o m p l o t # . i o n
a n o t h e r was im m e d ia te ly s e t up.
sap on ification
absorp­
a b s o r p tio n f l a s k s were th en a llow ed
i n t h e r e f r i g e r a t o r and s t o r e d u n t i l u t i l i z e d .
a tio n was c a r r i e d
The a c i d s added t o
t h e i r p u r i t y by means o f t h e
and i o d i n e n u m b e r s .
The r e s u l t s
VI and V I I .
tem perature u n t i l used.
Vo m a i n t a i n c o m p a r a b l e c o n d i t i o n s t h r o u g h o u t
the
to s o l i d i f y
period
t u b e s and t h e l a r d adde d a f t e r w h i c h
and a r e
o b t a i n o d on o x i d a t i o n n r o g i v e n i n T a b l e s
sh own g r a p h i c a l l y i n F i g .
7.
T a b l e VI
V ariation
of th e
In d u ction P eriod
o f Lard w i t h U n s n i u r -
a t e d F a t t y A c i d s and t h o F s t a r , 1. e t h y l h o u r a t e .
Uarrole
In du ction Period
.a v e r a g o
m ethyl baurate
231.6
n in .
: e t h y l 'ij a u r a t o
125.1
m in.
213,c
O leic
170.1
n in .
.170, 1
m n.
Ac i d
Iiin oleic
Ac i d
110. 3
b in o leic
Acid
1 1 0 . ■> n i n .
bard
1
I!o.
V o.
17",3
,■> s o r i a t x o n
-’. 8
•9
o
H
!
H
Table
!
90
V a r i a t i o n o f t h e Ind uo t i o n P e r i o d
F atty A cids
Sample
( 0 , 0 341 H)
I n due t i on P e r A o d
Lard Mo.
1
275. 5 n i n .
Lard Mo.
1
274.4 m in .
Lard Mo.
1
277.8 m in .
A c e t i c A ci d
244. 1 m in .
A c e t ic Acid
227.4 m in.
B u ty r ic Acid
229.7 m in,
B u t y r i c Acid.
224.8 m in .
Caproic Acid
223. 2 m in .
G a p ro i c A ci d
2 1 9 .1 rain.
G aprylic
Acid
2 2 4 . 7 m in
Oaprylic
A c id
2 55.8 m in .
2 1 1 .9 rain.
C opric Acid
2 2 1 .9 rain.
Laurie Acid
214.9 m in .
Laurie Acid
2 0 8 .
y .ristic
2 4 0 .7 min .
Acid
m
Average
;i V a r i a t i o n
27 5 , 9
1.2
235.8
7.1
227.3
2.1
n
1.8
o n n
« f-
»
Gauric Acid
5
o f Lard raith S a t u r a t e d
in .
I'yristic
Acid
225.9
n
in .
P alm itic
Ac id
8 3 4 . 2
m
i n.
P alm itic
Acid
n 1 n
O
<(../# r
rain .
S tearic
A ci d
1 8 8 .7 rain.
S tearic
A c id
202. 8 rain.
2 5 5 . 3
0.4
221.9
9 . 0
211.7
3 . 0
e~,
f.
rt
t O
886.1
1 9 3 . 8
1 . 6
n
n
n
*i
' « c’
l • 1-
91
270260250240230-
Lard Sam ple
No. I
220
210
200
-
-
-
V
I
(S3
zs
c
Q
O
o:
40-
LJ
CL
o
I—
o
3
Q
0
2
4
6
8
10
12
14
Num ber o f C a r b o n s in F a t t y Ac id
Mol ecu le
F ig u r e 7 ,
V a r i a t i o n o f t h e I n d u c t i o n P e r io d o f
L a rd w i t h S a t u r a t e d F a t t y A c id s
16
CONCLUSIONS:
F ig.
7 sh ows t h e v a r i a t i o n o f t h e i n d u c t i o n p e r i o d w i t h
i n c r e a s e d c a r b o n co n fc n t o f t h e a d d e d a c i d s .
The r e s u l t s
do n o t
show t h e same l i n e a r r e l a t i o n s h i p w i t h i n c r e a s e \ c a r b o n c o n t e n t
as i s e x h i b i t e d b y t h e v a r i o u s p h y s i c a l p r o p e r t i e s o f t h e a c i d s .
Since m o l e c u l a r p r o p o r t i o n s were u s e d ,
e a c h s a m p l e c o n t a i n e d an
e q u i v a l e n t number o f c a r b o x y l g ro u p s w hich sh o u ld t h e r e f o r e
an i d e n t i c a l i n f l u e n c e
in
each c a s e .
Fr om t h i s
exert
i t may b e c o n c l u d e
th a t tho ca rb o x y l group i s not re s p o n s ib le f o r th e v a r i a t i o n s .
To s u b s t a n t i a t e t h i s f u r t h e r , m e t h y l l a u r a t e w as a d d e d t o t h e l a r d
s am p l e u n d e r t h e
same c o n d i t i o n s
and a s u b s t a n t i a l d e c r e a s e i n
t h e l e n g t h o f i n d u c t i o n p e r i o d w as o b t a i n e d .
No d e c r e a s e i n t h e
l e n g t h o f t h e i n d u c t i o n p e r i o d w o u l d be e x p e c t e d i n t h i s
i f th e c a r b o x y l group were e n t i r e l y
responsible
case
since the c a r­
b o x y l g r o u p h a s b e e n m a s k e d by e s t e r i f i c a t i n r j a n d c a n e x e r t no
except
e f f e c t t h r o u g h h y d r o l y s i s w h i c h w o u l d n o t seem l i k e l y t o o c c u r
i n s u c h a f a t t y m e d iu m .
A c o m p a r i s o n o f t h e e f f e c t o f t h e Qs a c i d s may be made
from t h e r e s u l t s o b t a i n e d v /ith s t e a r i c ,
( T a b l e s V I and V I I ) .
o leic
Increased u n satu ratio n ,
and l i n o l e i c
acids
a s may be e x p e c t c - d ,
y i e l d s an o p p o r t u n i t } / - f o r i n c r e a s e d s u s c e p t i b i l i t y t o
oxidation
and a d e c r e a s e i n t h e l e n g t h o f t h e i n d u c t i o n p e r i o d .
To c h e c k t h e s e f u r t h e r ,
secured.
The s e c o n d l a r d
168 m i n u t e s .
The r e s u l t s
given i n T ab le V I I I .
ad d itio n al la rd
s a m p l e s ’/ e r e
sam ple y i e l d e d an i n d u c t i o n p e r i o d
f o r t h e l a r d s a m p l e n u m b e r two a r e
Upon a d d i t i o n o f t h e 0 . 0 3 4 1 U q u a n t i t y
of
T a b le V I I I
V a r ia tio n of th e In d u c tio n P e rio d of Lard w ith S atu ra te d
F a t t y A cids
In d u ctio n P eriod
Sample
L a r d No. 2
1 7 5 02 m i n .
L a r d Mo. 2
161.3 m in.
A c e t i c Acid
16 6 .4 m in.
A c e t i c Acid
16 4 .0 m in.
P r o p i o n i c A cid
149.9 m in.
P r o p io n ic A cid
183.0 m in.
P r o p io n i c A cid
1 6 4 .0 m in.
B u t y r i c A cid
17 9 .0 m in.
B u t y r i c Acid
1 8 0 .1 m in.
V a l e r i c Acid
200.8 m in.
V a l e r i c Acid
1 8 2 .9 m in.
V a l e r i c A cid
228.6 m in .
C a p ro ic A cid
19 7 . 0 m i n .
C a p r o ic Acid
169.9 m in.
of f r e e f a t t y
a cid s very l i t t l e
o b ta in e d from t h a t
noticeable
/£ V a r i a t i o n
168.3
8.2
165.2
1.5
165.8
25.9
179.6
0.6
204.2
22.3
183.5
14.7
d e v i a t i o n i n i n d u c t i o n p e r i o d Vcis
of the la rd i t s e l f .
o n ly when t h e l a r d i t s e l f
x i m a t e l y 200 m i n u t e s o r m o r e .
Average
A pparently the
e ffe ct is
o f f e r s s.n i n d u c t i o n o f a p p r o ­
Th e s h o r t e r t h e i n d u c t i o n p e r i o d ,
t h e l e s s n o t i c e a b l e .is t h e e f f e c t o f t h e a d d e d a c i d s .
94
L a rd number t h r e e ,
an o p e n - k e t t l e l a r d r e n d e r e d by a w e ll
knwon p a c k i n g c o m p a n y , g a v e a n i n d u c t i o n p e r i o d o f 248 m i n u t e s .
Saturated f a t t y
a c i d s were added i n t h e
under sample number o n e .
same m a n n e r a s d e s c r i b e d
A n u m b e r o f odd c a r b o n a c i d s w h i c h w o r e
a v a il a b le were a l s o added.
The r e s u l t s
obtained w ith t h i s
T a b l e IX a n d g r a p h i c a l l y
shown, i n F i g . 8 .
I t w i l l be n o tic e d t h a t
f o u r sam ples of
were r u n w i t h o u t o b t a i n i n g g o o d c h e c k s .
offered f o r t h i s
sample a r e r e p o r t e d i n
caproic a c id
No e x p l a n a t i o n c a n b e
b e h a v i o r on t h e p a r t o f c a p r o i c a c i d .
The a v e r ­
age o f t h e f o u r s a m p le s g i v e s a l o n g e r i n d u c t i o n p e r i o d t o c s.proic
than t h a t o b ta in e d f o r c a p r y l i c
a c i d - a. r e s u l t n o t i n c o n f o r m i t y
w i t h t h e t y p e c u r v e o b t a i n e d w i t h l a r d s a m p l e numb er o n e .
Two o f
th ese f o u r sam ples g iv e low er in d u c tio n p e r io d s th e n th e average
for c ap ry lic
a c i d - a f a c t w h i c h may o r may n o t be s i g n i f i c a n t .
A c e t i c a c i d w as n o t u s e d i n t h i s
atility ,
s e r ie s because of i t s
O xalic a c id in c re a s e d th e
considez'& bly,
high v o l ­
in d u c tio n p e rio d of th e la rd
T h i s i s t o be e x p e c t e d a s o x a l i c
a c i d h a s beer,
r e p o r t e d t o e.ct a s a n a n t i o x i d a n t .
EXTRACTION:
In ord er to
and t h e e f f e c t
o b t a i n o. b e t t e r u n d e r s t a n d i n g o f l a t o x i - t d u i o n
exhibited
w i t h 95/o e t h y l a l c o h o l .
by f r e e
acids,
a l a r d s a m p l e was e x t r a c t e d
T h i s wan a c c o m p l i s h e d by p l a c i n g t h o l a r d
in a flash
e q u ip p e d w i t h a lo n g neck ( a p p r o x i t u r t o l y f t
sid e arm.
A l o n g t a p e r i n g t u b e c l o s e s aw l u e
e.:.i
cm) a n a a
T a b l e IX
V a r i a t i o n of th o I n d u c t i o n P e r i o d of L ard vrith S a t u r a t e d
F a t t y A cids
In d u c tio n Period
Sample
Lard F o .
3
249.9 m in.
Lard N o.
3
2 4 3 .3 m in.
P r o p i o n i c A cid
211.1 m in.
P r o p io n ic Acid
198.7 m in.
L u ty rio A cid
225.3 m in .
a tyr xc
jxg x c.
218.5 m in .
V aleric
A cid
223.4 n i n .
V aleric
A cid
240.4- r a i n .
Caproic A cid
159.]. n i n .
Caproic A cid
194.2 n i n .
C aprcic A cid
516.2 m in.
Caproic A cid
1P
C a p r y li c Acid
1 7 7 .3 rain.
C a p r y l i c Acid
191.1 n i n .
Fa 1 a r y o n i c Ac i d
173.7 n i n .
P e 1 a r ;: o n i c A o i d
1.95.7 m i n .
P e 1 u r n ° n.i c Ac 5. d
133.0 n i n .
C apric A cid
1C 1 . 7 n i n .
Cr.pric A c i d
16 5 . 9 n i n .
^ rin
Average
7c
t V ariation
347.6
1.8
204.9
U,L'
3.1
231.9
in!
..a . o
194.5
1 3 4 .1
1.53.-0
s.. J
T a b l e IX ( c o n t i n u e d )
V a r i a t i o n o f t l i a 1 nd u c t i c n . P e r i o d , o f L a r d w i t h S a t u r a t e d
.Fatt y A cid s
S amp1 e
In d u ctio n . Period
L a u r i e Acid
114.8 m in.
L a u r ie A cid
14C:. 2 m i n .
L y ristic
A cid
184.5 m in.
L y ristic
Acid
1 9 1 .9 rain.
P a l m i t i c Acid
1 7 2 .1 rain.
P a l m i t i c Acid
159.6 m in.
S t e a r i c A cid
139.8 m in.
S t e a r i c A cid
O x a lic Acid
Average
V ariation
142.5
O-4 PO.
i_
188.8
'i n
165.8
7.5
13 3 . 8 m i n .
136.8
4.3
3 2 4 .5 rain.
324.5
_
e x c e p t i o n o f a f e w p i n p o i n t h o l e s was i n s e r t e d i n t h e n e c k oi t h e
f l n .s k so t h a t t h e
end
a cold f i n g e r p l a c e d
ing th e
u r o j
o c t e t u n d e r t h e s u r f a c e or t h o f a t
above th e to p o f th e tu b e .
a lc o h o l was
connected to th e
applied to keep th e
alcohol b o ilin g .
on t h e
cold f i n g e r
Cir av i t a t i o n t il f o r c e
side
and
A flank co n tain ­
arm and s u f i i c i c n t n e a t
The a l c o n o l v a p o r s con-., once a
a n d d r o p r e d down a n s i n e t h e t a p e ran.;,, -moo,
c a u s e d t h o a l c o h o l t o nxr i use- j.r.^o
o
- X
„ne, p i n p o i n t o p e n i n g s and r i s e t o t h o s u r f a c e w h e r e i s c o n ­
4- 1-
t i n u o u s ly flow ed b a ck
flask .
E x tractio n
by w e a n s o f i n e s lo w a m i u - . c
of th e
■>:C........ ^o-.ol
a l c o h o l s o l u b l e m a t e r i a l s took
•hi
97
250240230220
Lard Sam ple
No. 3
-
-
IND U CT IO N
PERIOD
(Minutes)
200
40-
2 3 4 5 6 7 8 9 10 II 12 13 14 15 16 17 18
N u m b e r o f C a r b o n s in F a t t y A c i d
M olecule
F ig u r e 8
V a r i a t i o n o f t h e I n d u c t i o n P e r io d o f
L a rd w i t h S a t u r a t e d F a t t y A c id s
during t h i s
contact p erio d .
Ox o.'ie a i ± x e r e n c e i n s p e c i f i c
T h i s e x t r a c t i o n was p o s s i b l e b e c a u s e
g ra v ity of th e la rd
and a l c o h o l and
t o t h e f a c t t h a t t h e s e tw o m a t e r i a l s a r e i m m i s c i b l e .
e x t r a c t i o n was c o n t i n u e d f o r 36 h o u r s a t t h e
w hi c h t i m e t h e
lard ras
e nd o f
s e p a r a t e d from t h e a l c o h o l l a y e r and as-
much o f t h e a l c o h o l a s p o s s i b l e r a s r e m o v e d f r o r : t h e l a r d by d e cant a t i o n .
The r e m a i n i n g a l c o h o l r a s r e m o v e d by h e a t i n g t h e
on a r a n t e r b a t h u n d e r r e d u c e d p r e s s u r e
lard
o b t a i n e d by a w a t e r p u n p .
Then a l l t h o a l c o h o l w as r e m o v e d a s i n d i c a t e d by no f u r t h e r d e ­
crease in w eig h t,
a t e n g r a m s a m p l e was o x i d i z e d i n t h e
absorption a p p a ra tu s.
A considerable decrease
( 68 ;=) i n i n d u c t i o n
p e r i o d w as o b t a i n e d a s t h e i n d u c t i o n p e r i o d w as f o u n d t o
m in u te s compared t o
oxygen
be 6 8 . 7
314.9 m in u te s f o r t h e u n c x t r a c t e d l a r d .
a l c o h o l e x t r a c t was h e a t e d on t h e w a t e r b a t h u n d e r va cu um t o
move t h e
alcohol.
A p o rtio n of t h i s
e x tr a c te d f a t to determ ine i t s
The r e s u l t s
r e s i d u e was a d d e d
au tio x id ativ e
activ ity .
o b t a i n e d a r e r e p o r t e d i n T a b l e X.
rr*
~ *1 ~ yr
XS . D l e A
V a r i a t i o n i n I n d u c t i o n P e r i o d o f L a rd b e f o r e and a f t e r
A lcohol E x tra c tio n
Sample
re­
Th e a l c o h o l f r e e r e s i d u e was c o l o r e d d a r k r e d
and h a d a d i s a g r e e a b l e o d o r .
to th e
The
In d u c tio n P eriod
F re s h Lard
Average
21At 9 m i n ,
E x t r a c t e d Lard
6 7 .3 min.
E x t r a c te d Lard
7 0 .1 m in.
E x t r a c te d Lard
7 3 .8 min.
68.7
R esistance to
d e c r e a s e d by t h e
ation i s
o x i d a t i o n o f la r d has been a p p re c ia b ly
alcoh ol
ex tractio n .
a m easure of th e
r e s u l t s w ould i n d i c a t e
uble m a t e r i a l s .
a n tio x id a n ts p resen t in the
th at
oxid­
lard ,
th ese
3ome h a v e b e e n r e m o v e d a s a l c o h o l s o l ­
H o w e v e r no l e n g t h e n i n g i n t h e i n d u c t i o n p e r i o d
was o b t a i n e d w h e n t h e
extracted l a r d .
during t h e
I f thd re s ista n c e to
e x t r a c t e d m a t e r i a l was combined w i t h t h e
T h i s may b e d u e t o
e x tr a c ti o n or to
a chem ical-change o c c u rrin g
a decom position of th e a n tio x id a n t
during t h e rem o v al of t h e a l c o h o l .
It
is p o ssib le th a t the a n t i ­
o x i d a n t s may h a v e be co m e o x i d i z e d d u r i n g t h e
e x t r a c t i o n and i n t h e
o x i d i z e d s t a t e w o u l d no l o n g e r p o s s e s s s u c h a c t i v i t y .
A seco n d sam ple o f l a r d
w ith 9 5 a lc o h o l i n th e
covered f r e e
sane m anner.
from a lc o h o l as b e f o r e .
i n i n d u c t i o n p e r i o d was o b t a i n e d ,
decrease).
( l a r d number t h r e e )
The e f f e c t
Again a c o n s i d e r a b l e d e c r e a s e
a c i d s on t h i s
and b u t y r i c
t h e seme m a n n e r a s p r e v i o u s l y d e s c r i b e d .
i n d u c t i o n p e r i o d was o b t a i n e d .
The i n i t i a l
by e x t r a c t i o n
ex tracted lard
a c id s to the
in
in
are g iv en in Table X I,
a rem oval of a n t i o x i d a t i v e m a t e r i a l , p r o ­
so lu b ility
in eth y l a lc ­
a n t i o x i d a n t s be removed d u r i n g e x t r a c t i o n ,
would be a n t i c i p a t e d
it
t h a t t h e i n d u c t i o n p e r i o d o f t h e f a t would
be no l o n g e r t h a n t h e t i m e n e c e s s a r y f o r o x y g e n t o d i f f u s e
the f a t .
lard
s h o rte n in g in th e in d u c tio n p e rio d caused
in d icates
ShotiTd a l l
(62/i
A fu rth e r decrease
The r e s u l t s
b a b ly h y d ro x y compounds b e c a u s e o f t h e i r
ohol.
l a r d was r e ­
248 m i n u t e s t o 90 m i n u t e s
of th e f a tty
was o b t a i n e d by a d d i n g p r o p i o n i c
The e x t r a c t e d
was e x t r a c t e d
The f a c t t h a t
in to
a n i n d u c t i o n p e r i o d o f 90 m i n u t e s was
T a b le X I
V ariatio n
o f the
I n d u c t i o n P e r i o d o f L a r d b e f o r e a nd
a f t e r A l c o h o l E x t r a c t i o n a n d t h e E f f e c t P r o d u c e d by t h e
A ddition
o f S a t u r a t e d F a t t y Acids*
Sample
In d u c tio n P eriod
L a r d Wo,
3
250 m i n .
L a r d Wo.
3
245 m i n .
8 9 ,7 m in.
A lcohol E x t r a c t e d Lard
9 1 .0 m in.
A le. E x t .
L a rd + P r o p i o n i c A cid
4 7 .1 m in.
A le. E x t ,
L a r d + P r o p i o n i c Acid
5 5 .1 m in.
3 + P r o p io n ic A cid
L a rd + B u t y r i c A cid
G2.9 m in .
A le. E x t .
L a rd + B u t y r i c A cid
74.9 m in.
It
in d icate th a t
l a r d and i t s
sam ples.
58.9
an tio x id an ts
h old betw een t h e
o.cid s a m p le s and t h e
had not
oeen removed
a d efin ite re la tio n ­
in d u c tio n p e rio d s of the fre s h
ex tracted
lard
and i t s
acid
A lc o h o l e x tr a c t i o n red u ces th e in d u c tio n p erio d of the
l a r d from 243
to
90 m i n u t e s .
o f 243 m i n u t e s w h i l e t h e
period of
all
m a y b e n o t e d f r o m T a b l e XI t h a t
ship a p p e a rs t o
51.1
221.9
3 + B u t y r i c A cid
obtained w o u ld
90 .4
204.9
A le. E x t .
L a r d Wo.
lard
248
A lcohol E x t r a c t e d L ard
L a r d Wo.
Average
20 5 m i n u t e s ,
lard
F r e s h l a r d h a s an i n d u c t i o n p e r i o d
and p r o p i o n i c
a decrease
a c i d had an i n d u c t i o n
o f 43 m i n u t e s w h i l e t h e e x t r a c t e
s a n o l e s w e n t f r o m 90 m i n u t e s f o r t n e
l a r d ~o ^1 nxnu'.-e.-j o r ^ i . e
101
lard + p r o p i o n i c
acid,
a decreo.ce o f
propionic a c i d t o f r e s h l a r d
39
or e x tr a c te d
io n p e r i o d a n a v e r a g e o f 4 1 m i n u t e s .
with th e a d d i t i o n o f I m t y r i c
acid .
The a d d i t i o n o f
la rd reduces th e in d u c t­
S im ilar r e s u lts
r e d u c e d f r o m 24 8
t o t a l o f 26 m i n u t e s .
When a d d e d t o
noted
m i n u t e s t o 222 m i n u t e s o r a
^retracted
period i s
r e d u c e d f r o m 90 m i n u t e s t o
m inutes.
The a v e r a g e r e d u c t i o n i s
lard ,
the in d u c tio n
6 9 m i n u t e s o r 8. t o t a l o f 21
24h
m inutes.
These r e s u l t s
in ­
r e d u c t i o n i n i n d u c ' i ^ i o n p e r i o d due t o t h e a d d i t i o n
of p r o p i o n i c o r b u t y r i c
acid to
a fre s h
The f r e s h l a r d a n d t h o
ex tracted
lard l
amounts o f a n t i o x i d a n t s y e t t h e
l a r d a nd a n e x t r a c t e d l a r d .
sample c o n t a i n d i f f e r e n t
s .d d i - T b i o n o f t h e f a t t y
a s im ila r d e c re a s e i n i n d u c t i o n p e r i o d of each of th e
fr om t h i s
are
W luen added t o f r e s h l a r d , th e
induction p e rio d i s
dicate a d e f i n i t e
m inutes.
i t may b e c o n c l u d e d t h a t
acids causes
sam ples,
ice e f f e c t of t h e f a t t y
acids
i s n o t c o n t r o l l e d by t h e
amount o f e n n t i o x i d a n t s p r e s e n t i n t n e
f t a.
a c i d s catr..T_-yze t h e o x i d a t i o n by d e s t r o y ­
I f the
added f a t t y
i n g t h e a n t i o x i d a n t s , t h e y do s o e q u x s J . l y i n a l l
the v a r i a t i o n
in th e in d u c tio n p e r i o d s
cases.
Therefore
c a n n o t bo due t o t h i s
reaction,
OXIDATION OF PURE FATTY ACIDS:
In a f u r t h e r a tte m p t to
w understand th e
by t h o a d d i t i o n o f s m a l l a m o u n t s of'
s a m p l e s o f two s a t u r a t e d
allow ed t o
absorb oxygen.
manner a s t h e l a r d
w as o b t a i n e d .
(so lid )
fatty
ac id s,
e f f e c t produced
acids to
lau ric
lard ,
lu g ra n
a n d m y n s t n . c , —o r e
E a c h "a- . p i e v’a s T r e a t e d
an '/tie m-ne
sam ple and a r e c o r t l o f t n e oxygon a n o o r p <
, ion
L aurie
a c id gave an
i n d u c t i o n p e r i o d o i a p p r o Aim/to .•
102
1743 m i n u t e s w h i l e m y r i s t i c
a c i d g a v e 923 m i n u t e s .
A lth o u g h slow
a b s o r p t i o n o f oxygen t o o k p l a c e a f t e r the i n d u c t i o n p e r i o d , t h e
c u r v e o b t a i n e d was t y p i c a l l y
of t i m e .
Fresh la u ric
o x i d e n u m b e r of
1 .9 .
auto cataly tic
over th e
longer perio d
a c id gave a n e g a t i v e K re is t e s t
and a p e r ­
A f t e r oxygen a b s o r p t i o n , t h e K r a i s t e s t
showed a f a i n t p i n k a n d t h e p e r o x i d e n u m b e r was 3 7 . 0 .
ind icate t h a t co n trary to
are o x i d i z e d .
ordinary b e l i e f s
T h i s would
the s a t u r a t e d a c id s
F o r m a t i o n o f p e r - a c i d s w o u l d seem l i k e t h e m o s t
l o g i c a l e x p l a n a t i o n a nd w o u l d a c c o u n t f o r t h e i n c r e a s e i n p e r ­
oxide n u m b e r.
cance,
The f a i n t - K r e i s t e s t
as a s p l i t
is
of q u e s tio n a b le s i g n i f i ­
i n t h e c a r b o n c h a i n o f t h e a c i d t o form e p i -
h y d rin a ld e h y d e does n o t soon r e a s o n a b le i n th o l i g h t
ent day o x i d a t i o n t h e o r i e s .
unsaturated
of t h e p r e s ­
The f r e e d o m o f t h e l a u r i c
a c i d fr o m
a c i d c o n t a m i n a n t s n a y b e j u d g e d fr o m t h e i o d i n e num­
b e r w h i c h was f o u n d t o be 0 . 2 .
The s a p o n i f i e n t i o n n um be r was
f o u n d t o b e 201 r s c o m p a r e d w i t h t h e t h e o r e t i c a l 2 0 0 .
To
samples
0,03d! I’ c u a n t i t i e s
clone i n
upon
order
to
saturated
Table X I I .
addition,
results
of
acids.
These
lauric
oleic
observe
the
The
results
acid
acid
acid
arc
' fho c u e s i i o n
K reis
samole
also
and n y r i c t i c
md
effect
results
lino, oic
produced
obtained
s h o w a. n a r k e d
of th e u n s a tu r a te d a c id s .
produceda p o s itiv e
linoleic
of
test
gave
and
rend i l 'r n t i r i h u ' " re 1 o t o
of r r e f s r e n t i r 1
toe
aro
as
' t h i s ’ ' pa
Pol!owe
reins
no
j w o d u c c v l by t h o
a.ciu
clone
• . r o xs t c s - .
nxl . e i ?■on
o.
added
by un s a t u r a t e d
a p e ro x id e nuweer
o. p o s i t x v o
mere
a.eidr,,
catalysis
Lauric
acid
o>
no i d
on.
Fn o
■- to. sc
s o Juu,-' . , c 1 •"cin*.
u-.r a- 1 r ■' -e
. '
Table X II
V a r ia tio n of th e
Induction
of S a tu ra te d F a tty
A c id s v / i t h
U n s a t u r a t e d F a t t y A cids
Sa m ple
I n d u e l i o n ]P e r i o d
L a u r ic Acid + O le ic Acid
46 3 . 4 m i n .
I .a u r ic Acid + L i n o l e i c
1 3 2 .6 min.
g ristle
Acid
A c i d •(• O l e i c A c i d
3 2 6 .2 min.
J ' . y r i o t i c A c id + L i n o 1 e i c A c i d
2 7 9 . 4 m in .
P a l m i t i c Acid- + C l o i c A c i d
3 0 0 . 8 min .
P a l m i t i c A c id + L i n o l e i c
1 0 2 , 0 m in .
A c id
before p e r -u c id f o r n e tio n in th e satu rated rc id s
arnno,
attempt t o
( 0 . 0 3 4 1 .") o f
answer -th is q u e s t i o n s m a ll quant i t ion
t h e unsuviu r a t e d a c i d s n e r e a d d e d t o
vent as n i i i R r i l o i l ,
Tho r e s u l t s
10 g r a n s o f
an i n o r t
In in
so l­
are g iv e n in Table X I I I .
Table X III
Va . r i a t i o n
of t h e
Un o ? +■u r a t ed I ’a t t y
induction r e r i o t
Ac.i d s a m
the d s t o rj
: e t -ayl 1.a.urn oe
I n d uc t i a n P e r i o d
S a m p le
I l i n e r a l O il + O leic
o f . i ne. r a . j . u i l v.'.i.tn
A c id
b i n e r a ! O il + L i n o l o i c Acid
•' i n o r a l O i l + l e t h y l n o -u r ate
176. 6 • ;i r .
The o x y g e n a b s o r p t i o n
graphically
studied
a c i d a nd l i n o l e i c
a c i d o b t a i n e d i n t h i s way v/as
along w ith th e
acid .
w hi c h s u g g e s t e d t h e
posedly i n e r t
of l i n o l e i c
so lv en t.
of a b s o r p tio n
o f o x y g e n by t h e
cup-
A 10 g r a m s a m p l e o f m i n e r a l o i l w a s o l s c e d
in the a b so rp tio n a p p a ra tu s
and i t was fo u n d t h a t t h o m i n e r a l o i l
larg e q u a n tity
of oxygen,
i o n and g l y c e r o l w e r e i n d e p e n d e n t l y t r i e d
oxygen,
of l a u r i c
Only c o n f u s i n g r e s u l t s w ore o b t a i n e d
question
absorbed a r e l a t i v e l y
oxygen a b s o r p t i o n
'The K r e i s t e s t was u s e d
A petroleum Tract
but th e se
on t h e g l y c e r o l
also
absorbed
s a m p l e b u t no
c o l o r a t i o n w as o b t a i n e d w h i c h w o u l d i n d i c a t e w i t h o u t d o u b t t h a t
ep i h y d r i n a i d e hyd e i s
n o t form ed from ^ y c e r o l ,
ho s u i t a b l e
solvent
which d i d n e t a b s o r b
o x y g e n w a s f o u n d a n d t h i s p h a s e o f t h e ’ve rb
v/as a b a n d o n e d .
P referen tial,
oxid ation
of th e un satu rated
d e f i n i t e l y b e d et er m i n e d f r o m a s t u d y
rate of
oxygen
c d d i t i on o f
of
o leic
absorption i s
lin o leic
acid ,
plo. ee r a p i d l y
appears t o
im m ed ia tely
appear t h a t
the
lau ric
form ation
the f a c t
that
the
approxim ate t h a t
of li n o l e ic
slop e
o f tho
o* t a i n e d .
is
acad,
case
an c o r
a b s o r p tio n tpi:es
i n d u c t a o n p e r i o d j and
o leic
acid.
acid ta xes
decreo.se
I t w o u l d t vus
oxidized p r e f e r e n i l e . l l y
saturated
The
of the
reads tarn
which- a f t er a. n o t i o e a o l o
occur w ith
acid
of tho
and myr i 3 t i c
f o i l ow ing t h e
does not
lin o le ic
per-acid
It
to
a maximum o f t e r
T his
of th e resu l i s
much more n a r k 9cl i n t h e
W ith a d d i t i o n
roach
takes p l a c e .
acid
a c id s can not
and t o o n
o l a c e , in.dacu.«sd
o f t h e l a t t e r p a r t o f th e cu rv es ten d s to
saturated, a c id s
a lo n e.
seem s r e a s o n a b l e t h a t m ore p ro n o u n c e d r e s u l t s would
be o b t a i n e d w i t h l i n o l e i c
a cid than o le ic
a c a -1 r,un
„o *00
^
tendency t o
oxidize.
the e f f e c t
Under th e c o n d itio n s
e x e r t e d by o l e i c
uction p e r io d i s
not n o ticeab le
experim ents
a f t e r the
in d ­
over.
The r e s u l t s
three s a t u r a t e d
acid is
of th o se
o b t a i n e d when o l e i c
a c i d was ad d ed t o t h e
a c i d s may b e f o u n d i n T a b l e XXV.
T a b l e XIV
V a ria tio n of th e
In d u c tio n P e rio d of Pure S a tu ra te d F a tty
A c id s w i t h O le ic A cid
In d u ctio n Period
Sample
L auric
4 6 3 .4 m in.
Acid
M y ristic
A cid
3 2 6 .2 m in.
P alm itic
Acid
3 0 0 .8 m in.
In a l l t h r e e
a c i d s t h e r e v/as a s h o r t e n i n g o f t h e i n d u c t i o n p e r i o d
w ith I n c r e a s e d m o le c u la r w eig h t
of o l e i c
acid
of th e s a t u r a t e d
acid.
10 g r a m s
g a v e t h e f o l l o w i n g i n d u c t i o n p e r i o d s 2 2 . 2 and 2 1 . 3
m inutes ( a v e r a g e
21.8 m in u te s ) .
Th e r e s u l t s
f o u n d i n T a b l e XV.
o b t a i n e d when l i n o l e i c
L inoleic
acid
duction p e r io d of 1 4 .3 m in u te s.
same r e l a t i o n s h i p a s ' w a s t r u e
cu lar w eight but r a th e r
the s a t u r a t e d f a t t y
(10 grams)
itse lf
These r e s u l t s
of o le ic
show t h e
a c i d v/a3 u s e d may be
gave an i n ­
do n o t show t h e
a c i d w i t n i n c i e a s e ^ m ole­
s t e p - w i s e t r e n d a s e x h i b i t e d w ne n
a c i d s were added to l a r d ,
M yristic
a much l o n g e r i n d u c t i o n p e r i o d t h e n t h e o t h e r tw o a c i d s .
acid nas
Time d i d
106
T a b l e XV
V aria tio n of th e
In d u c tio n P e rio d of Pure S a tu r a te d F a tty
A c id s w i t h L i n o l e i c Acid
Sample
In d u ctio n P eriod
L a u r i c A cid
13 2 .6 m in.
M y r i s t i c A cid
2 7 9 .4 m in.
P a l m i t i c A cid
102.0 n i n .
not p e r m i t an a n a l y s i s
of a l l th e
s a t u r a t e d a c id s i n t h i s m anner.
S o lid a c i d s w ere u s e d b e c a u s e t h o s e
te m p e ra tu re w ould v o l a t i l i z e
able r e s u l t s
in th is
f u r th e r s u b s ta n tia te th e b e lie f th a t the
a n t i o x i d a n t s have no p a r t i n
causing the v a r ia tio n in ind u ctio n
a d d itio n of th e
An a n a l y s i s
samples o f o l e i c
to o
determ in atio n .
These r e s u l t s
period w ith th e
a c i d s w h i c h a r e l i q u i d a t room
o
r e a d i l y a t 10 0 C t o g i v e c o m p a r ­
of th e
and l i n o l e i c
fatty
acid s.
a b s o r p t i o n o f o x y g e n by t e n gram
acids
gave t h e f o l l o w i n g r e s u l t s :
O l e i c a c i d a b s o r b e d a p p r o x i m a t e l y 38 ml o f o x y g e n ( a d r o p o f 10
cm) i n 6 5 5 m i n u t e s w h i l e l i n o l e i c
tity
i n 247 m i n u t e s .
but d i f f e r e n t i n
acid absorbed th e
Both c u r v e s w ere l o g a r i t h n e t i c
s l o p e which, i s
r a t e s of oxygen a b s o r p t i o n .
same q u a n ­
in nature
an e x p re s s io n of th e d i f f e r e n t
107
C0HCLUSI0riSj
The s a t u r a t e d f a t t y
a c i d s c a t a l y z e th e o x i d a t i o n of
lard w ith tho p ro d u c tio n of a s e r ie s
of unusual r e s u l t s .
The s h o r t ­
en in g o f t h e i n d u c t i o n p e r i o d i n n o t due t o i n c r e a s e d m o l e a u l a r
weight of t h e added a c id o r in i t
due t o t h e c a r b o x y l g r o u p an e a c h
acid i s p r e s e n t i n e q u a l m o le c u la r q u a n t i t i e s .
pro-oxidants p o ssib ly
tio n d ire c tly
exert the
They do n o t f u n c ­
h o w e v e r by d e s t r o y i n g t h o n a t u r a l a n t i o x i d a n t s a s t h e y
same r e l a t i v e
erent q u a n titie s
directly
in t h e form of p s r - a c i i s .
T h e s e a c i d s .act a s
effect
on s s m p l o s o f l a r d c o n t a i n i n g d i f f ­
o f a n t i ox i d a n t s .
on t h e f a t
These a c i d 3 nay t h e r e f o r e a c t
in s te a d of the a n tio x id a n t.
can n e t e x e r t t h o i r f u l l
e f f e c t in th e presence
Tho a n i i o x i d a n t s
of t h e
added a c i d s .
EFFECT OF GASES Oh TIT. OXIDATIOx OF LARD*
The e f f e c t
o f s e v e r a l g a s e s on l a r d w a s s t u d i e d by means
of th e a b s o r p t i o n a p p a r a t u s .
A sample of l a r d v /ith an i n d u c t i o n
p e r i o d c f 1 3 3 . 5 m i n u t e s v’os p l a c e d i n t h e over, s i ICO 1 a n d I r e c f x . n
as p r e v i o u s l y
d escribed,
A’r r b o n d i o x i d e v a s u s e d i n p l a c e o f ox y­
ge n b o t h i n t h o r e s e r v o i r and i n t h e
ing a b s o r p tio n cu rv e
a b s o r p t i o n f . la .sk .
c h o r 'C'’ no i n d u c t i o n p e r i o . a as i t
die r e s u l t ­
m d v :itn oxy­
g e n b u t a s l o w g r a d u a l a b s o r p t i o n o f CO*-; o v e r a p e r i o d o f -iC h o u r s
a s i n d i c a t e d by a d e c r e a s e i n p r e s e n c e a t a p p r o x i m a t e l y h a l f h o u r
in te rv a ls.
' J u l y n. s l i g h t
a c c e l e r a t i o n of th e r a t e
TOn may b e n o t i c e d o v e r t h e 40 h o u r p e r i o d .
fOo a c r e
a b s o r b e d la ' t ' T
o f f 0s seems l i k e
lard .
^C y w c
color.
. o s o r p t x o n ox
^ . p p r o x i a r . i t c l y 2 n ml
in
xours.
...h.j vQ.Liu.iO
an e x c e s s i v e ; r x t m i f o r m e re s o l u b i l i t y
The l a r d g a v e a. p-’ nk f r e i s
negative
of l a r i
of
A strong acrid
in the
t e s t -v >xlc t n c a r c s •. ?. ° r \ . " r "va a.
o lor w s
acted
m i
vot
108
cid o d o r .
Tno p e r o x i d e
nu mb er b e f o r e a b s o r p t i o n v/as 8 . 5 v b . i l g a f t o r
u b s o r p t i o n v/as 2 5 . 6 .
Tho same s a m p l e o f l a r d w as t r e a t e d
nitrogen g a s .
i n l i k e manner w i t h
Ho a b s o r p t i o n had t a k e n p l a c e a x s r 10 iiovii'o .
i ;iG
f a t ga ve a n e g a t i v e K r e i s t o s t a n d hacl a p e r o x i d e v a l u e o f 3 . 7 .
The s l i g h t
i n c r e a s e i n p e r o x i d e number o v e r t h e f r o s h sample ( 2 .5
t o 3 . 7 ) may r e a d i l y b e due t o t h o e x p e r i m e n t a l e r r o r o r i t m i g h t
o
i n d i c a t e t h o a c t i v i t y a t 100 o f t h e d i s s o l v e d o r l o o s e l y boun d
oxygen h e l d by t h e f r e s h l a r d .
T his l a t t e r
s u g g e s t i o n would
a p p e a r t o b e s u b s t a n t i a t e d by t h e f a i n t i ' r e i r t o s t .
F u r t h e r s t u d i e s v .' ith G0S on a n o t h e r l a r d c a m p l e ( i n d ­
uction p e rio d
247.6 m inuter,)
sorbed as b e f o r e y i e l d i n g
the r e s u l t i n g
gave s i m i l a r r e s u l t s .
C02 was a b ­
snip e r i i n p os a b l e a b s o r p t i o n c u r v e s and
sample gave r f a i n t b u t d e f i n i t e pink h r e i s t e s t
(both f a t and a c id l a y e r b e in g c o l o r e d ) .
’.’o c l a r i f y
t h e p r o b l e m a s a m p l e o f t h e a b ov e l a r d v/as
h e a t e d on a w a t e r b a t h u n d e r r e d u c e d p r e s s u r e
pump t o
remove t r a c e s
ly bound t o t h e f a t .
o o t a i n e d oy a v a t o r
o f ox y g o n v / h i c h m i g h t bo d i s s o l v e s o r l o o s e ­
The s a m p l e - v/as t h e n p l a c e d i n t h e oven and
the sy stem f i l l e d v /ith oxygen.
of t h e o x y g e n a b s o r p t i o n
V i t k i n t e n m inutes of th e s t a r t .
a d r o p o f o v e r 6 mn ( c r an a b s o r p t i o n oi
a p p r o x i m e . t e l y 8 ml o f o x y g o n ) t o o k p l a c e i n d i c a t i n g a r a p i d d i f f u s ­
ion o f t h e
oxygen i n t o t h e f a t .
p e rio d of 210.1 m in u te s ,
a loss
T h i s s a m p l e ncv ga ve a n mo. a c t i o n
of 37.5 m in u te s .
p l a i n e d by t h e i n c r e a s e d a c t i v i t y
gen i n p l a . e e o f t h e
T h i s n a y be e x ­
due t o t h e p r e s e n c e o~ p u r e o x y ­
dissolved g ases,
n.itx’c .r e n , e t c . ,
rq.li ir- s o lu tio n
109
by t h e f r e s h f a t .
A n o t h e r s a m p l e o f l a r d was e v a c u a t e d on t h e
as d e s c r i b e d a nd a f t e r i n t r o d u c t i o n i n t o t h e
t r e a t e d v / i t h C03 i n p i e c e
of oxygen.
steam lo a th
a b s o r p t i o n s y s t e m v/as
To be s u r e no o x y g e n m a s p r e s ­
e n t i n t h e C02 , t h e g a s f r o m t h e c y l i n d e r v/as b u b b l e d t h r o u g l s . t w o
t o w e r s c o n t a i n i n g p y r o g a l l o l and s o d i u m c a r b o n a t e b e f o r e a d m i . t t a n . e e
to the a b s o r p tio n f l a s k
and r e s e r v o i r .
pressu re in th e system r a s
Ho im m e d ia t e d e c r e a s e
obtained but a t th e
r a p i d a b s o r p t i o n o f C0 2 w as n o t e d .
in
end o f t e n m i n u t e s
D uring t h e
n e x t 45 m i n u t e s t h e
a b s o r p t i o n o f C02 be c a m e , l e s s p r o n o u n c e d a n d b e g a n t o a p p r o x i m a t e
t h a t o b t a i n e d by t h e o t h e r l a r d - C 0 2 a b s o r p t i o n s a m p l e s ( t h a t
is,
s u p e r i m p o s e a b l e c u r v e s - same s l o p e and som e r a t e o f a b s o r p t i o n ) .
The s a m p l e s sh owe d a v e r y f a i n t p i n k K r e i s t e s t .
CONCLUSIONS:
From t h e s e r e s u l t s i t may b e c o n c l u d e d t h a t a
c a n be s a f e l y
stored
or o x id a tio n o c c u r s .
by a b s o r p t i o n o f t h e
jfat
i n n i t r o g e n s i n c e a p p a r e n t l y no a b s o r p t i o n
S t o r a g e i n C02 l e a d s t o
gas.
an o f f - o d o r cm u s e d
D iffu sio n occurs f i r s t
f o i l owed by a. r e a c t i o n b e t w e e n t h e f a t a n d C02 .
i n d u c t i o n p e r i o d and i t s
apparently
C02 g i v e s
no
d i f f u s i o n c u r v e may bo r e a d i l y d x s t o a n g ­
u i s h e d f r o m t h e a p p a r e n t r e a c t i o n c u r v e by t . a e s l o p o o f t h e
ine
curve.
The p o s i t i v e r e a c t i o n w i t h t h e i v r o x s t e s t i n d i c a t o r t j i e
p r e s e n c e o f o x y g e n w h i c h c a n be q u i t e r e a d i l y removed by e v a c u ­
a tin g the f a t
on a s t e a m b a t h w i t h a w a t e r p u n p .
traces
oj.
gon i n a f a t w i l l c a t a l y z e t h e o x i d a t i o n o f t h e f a t i n t h e
of n i t r o g e n and c a rb o n d i o x i d e .
oxy­
presence
VARIATIONS IN THE PHYSICAL AMD CHEMICAL CONSTANTS OF VARIOUS FATS
AMD OILS CM THE ABSORPTION OF DEFINITE VOLUMES OF OXYGEN*
S ix f a t s w ere c h o se n f o r t h i s
of t h e v a r i o u s t y p e s
drying an im al f a t s *
ated) j o l i v e
o il,
study as r e p r e s e n t a t i v e s
of f a t t y m a t e r i a l s .
crisco ,
L a r d a nd b u t t e r f a t ,
a non-drying v eg eta b le f a t
a non-drying v e g eta b le o ilj
som i-drying v e g e ta b le o i l j
lin seed o il,
non­
(hydrogen­
cottonseed o i l ,
a
a drying o i l .
A b s o r p t i o n o f o x y g e n t o o k p l a c e a t a t e m p e r a t u r e o f 98
o
99 C ( i n b o i l i n g w a t e r ) .
The o x i d a t i o n a p p a r a t u s v/as s i m i l a r t o
t h a t u s e d by T r i e b o l d ; a n d B a i l e y
v/as w e i g h e d d i r e c t l y
in to the
m ercury-sealed s t i r r e r .
(1932).
E a c h 100 gr a m s a m p l e
a b s o r p t i o n f l a s k equipped w i t h a
O x i d a t i o n v/as a l l o w e d t o t a k e p l a c e u n t i l
t h e d e s i r e d volume o f oxygen had b e e n a b s o r b e d .
ected w ere:
10 m l . ,
o
50 m l . ,
100 m l . ,
250 m l . ,
m l . o f o x y g e n a b s o r b e d p e r 10 0 g r a m s o f f a t .
The v o l u m e s s e l ­
500 m l . ,
and 1000
Each o f t h e o x i d i z e d
s a m p l e s a s w e l l a s t h e f r e s h f a t was a n a l y z e d f o r t h e f o l l o w i n g :
S a p o n i f i c a t i o n Humber
I o d i n e Number
P e r o x i d e Humber
F r e e F a t t y Acid Value
R e i c h e r t - H e i s s l Humber
P o l e n s k e Humber
A l d e h y d e Number
R e f ra c tiv e Index
K reis Test
C olor,
Odor and A p p e a r a n c e
Ill
When t h e d e s i r e d v o l u m e h a d b e e n a t t a i n e d ,
e a c h s a m p l e was f r e e d
f r o m d i s s o l v e d o x y g e n b y i m m e d i a t e l y t r e a t i n g w i t h n i t r o g e n and
t h e a n a l y s e s made a s r a p i d l y a s p o s s i b l e .
S a p o n i f i c a t i o n H u m b e r:
(Fig. KOH/gm f a t )
0 . 5 H KC1 w a s u s e d f o r b a c k t i t r a t i o n .
A 5 gram s a m p l e was u s e d .
R ef.:
A.O.A.C. 4 t h E d i t i o n ,
Pa ge 4 1 2 .
I o d i n e N u m b e r:
(Oms i o d i n e / l ' O O gms f a t )
Tho w e i g h t o f t h e s a m p l e
u s e d was d e p e n d e n t u p o n t h e u n s a t u r a t i o n o f t h e r e s p e c t i v e f a t s ,
0 , 1 N T h i o s u l f a t e v/as u s e d f o r b a c k t i t r a t i o n .
E dition,
Page 410.
P e r o x id e Number:
( h i s 0 .0 0 2 H Thio/gm f a t )
was d e p e n d e n t u p o n t h e
The w e i g h t o f t h e s a m p l e
e x t e n t of o x i d a t i o n .
was u s e d f o r t i t r a t i o n .
d o tern in atio n .
NaOH.
A .O .A .C. 4 t h E d i t i o n , Page 417.
Re i c ho r t - l i e i s s 1 Humber:
fatty
were u s e d .
Polenske
atile
insoluble
a c i d s from f i v e
from f i v e
volatile
14L->k‘ E d i t i o n ,
5 gram c a m p l e s
in the t it r a t io n *
e m p l o y e d
( P . l s 0 . 1 II a l k a l i
acids
4etcm inn.tion.
A
grams o f f a t )
of f a t
E ef.:
a .O .a .o ,
Page 4 1 4 .
Nurabor:
fatty
T i t r a t i o n v/as c a r r i e d c u t w i t h u . l I!
( i ' l s u . l *.! a l k a l i t o n e u t r a l i s e t h e o o l u o l e
0 . 1 i! ITnOH w as
4th E d itio n ,
(19 2 3 ) .
T w e n ty grams o f f a t was
used in t h i s
R of.:
0 . 0 0 2 II t h i o s u l f a t e
R e f . : Holm and G r o e n b a n k
F r e e F a t t y A c i d V a l u e : (Gms KOH/grn f a t )
v o la tile
R e f . : A .O.A.C. 4 t h
fatty
grans
acids
T itration
to
of
neutralize
fat)
obiainca
t.io
a.::;', e l u d e
vol­
A n a l y s e s w r r e r a n on ~.\o
durxr.g t h e
wos made v x t C . 1 -
■a~
he men
,
r. 'i
•
<
-cs .
Page 415.
1
>
»T
i
^ l“Ia c1 .jy
o .e
: :Ur'nnr:
f ' "y .
~
f ■l”
"S
V
.. .at.
.... ',“1 —0/
'T
'
-*"1 *\
i
1 ' 1’ ’‘ ;1
.
- ~a.......... ..........
■ .
C T*
11.
used and back t i t r a t i o n
r e s u l t s w ere o b ta in e d
F urther r e m i t s " 'i l l
R efractive
order to
U n reliable
i n a l l a n a l y r . e e du e a p p a r e n t ! *• t o t h e n e t hod*
n o t be r ; i v e n , R e f . :
Lea,
(1134).
Index:
T h i s v/as o b t a i n e d on a n Abbe R e f r e a c t o n r t r - r .
In
o
o b t a i n c o m p a r a b l e r e s u l t s , a t e m p e r a t u r e o f 40 0 v/as u s e d
v’i t h a l l f a t s
liq u id
a c c o m p l i s h e d w i t h 0.CG2 U I 2 .
state.
r nd o i l s .
R ef.:
At t h i s t e m p e r a t u r e r l l s a m p l e s v/crc i n t h e
A .O .A .C. 4 t h U d i t i o n , F are 4 05.
I ' r c i s T o o t : T h i s t o o t v/as r u n o n l y q u a l i t a t i v e l y .
An e q u a l volu m e
o f c o n c e n t r a t e d A l l v/as a d d e d t o t h o v o l u m e (0 - 3 m l . )
f a t ana t h e sample s h a k e n .
To t h i s
o f a V ; l o r o y l u c i u o l w as a d d e d .
a p e r o x i d e - f ree
e th e r solution,
The d e v e l o p m e n t c f a p in !: t o
i n t h e a c i d l a y e r was t h e c r i t e r i o n
of ran cid ity .
rh e
t h e c o l o r vvr.s n o t e d r o u y h l y a nd "/as r e p o r t e d . a s p i n k ,
C olor,
Odor rood Acp c nrr uic <r:
in a l c o lo r of tho f a t ,
th o
of m elted
'T/in i r e l u t e d
a p p e a r ■■ncs o f a
red c o l o r
i n t e r " ity
red or aar-T c.
b 1 each?, ■a'" o f t h e a m p ­
rancid
of
o d o r , m'a-.
LARD
The s a m p l e w as a l l o w e d t o m e l t a t a low t e m p e r a t u r e and
w hile
still
in the liq u id
Under t h e s e
ffcate u n i f o r m s a m p l e s v/ere w e i g h e d o u t .
co n ditions of o x id atio n ,
t h e i n d u c t i o n p e r i o d v/as 2 -
2 l / 2 hours w hile r e s u l t s in th e o v e n -ab so rp tio n ap p aratus
co n d itio n s)
(static
g a v e en i n d u c t i o n p e r i o d o f 20 0 m i n u t e s .
T a b l e XVI
The C h e m i c a l a nd P h y s i c a l V a r i a t i o n s o f L a r d on A b s o r p t i o n o f D e f ­
i n i t e V ol um e s o f Oxygen
0
10
50
100
250
500
1000
65.1
64.7
64.5
64.5
63.3
60.4
57.9
P e r o x i d e Mo,
0.3
8.3
25.2
39.3
92.0
162.6
259.6
S a p o n i f y No ,
195,5
195.2
195.8
196.5
197.1
199.0
204.2
I o d i n e No,
F r e e F a t t y Acid
0.85
0.82
0.88
0.96
1.26
2.05
3.00
R e i c h . - I V e i s . No,
0.36
0.13
0.18
0.22
0.33
1,16
1.63
P o l e n s k e No,
0.25
0.30
0.27
0.32
0.30
0.27
0.30
R efractive
Index 1.4596
1.4596
1 .4 5 9 7 1,4600 1.4602 1.4605 1.4616
Red
Red
Red
Red
K reis Test
Meg.
Pink
Red
Odor
Fresh
Fresh
F a i n t R a n c i d Ranc i d R a n c i d Ranc i d
A ppearance
Sa m p le s h a v e a t e n d e n c y t o become y e l l o w on o x i d .
BUTTERFAT
U n s a l t e d b u t t e r was a l l o w e d t o m e l t a n d when l i q u i d , f i l ­
tered to
salts.
sorption
o b t a i n t h e b u t t e r f a t f r e e f r o m w a t e r , p r o t e i n s a nd m i n e r s . l
O x i d a t i o n was c a r r i e d o u t on t h i s f a t .
s t a r t e d a f t e r approxim ately s ix h o u rs.
A c t i v e oxygen a b ­
S ta tic conditions
ga ve a n i n d u c t i o n p e r i o d o f 443 m i n u t e s .
T a b l e XVII
The C h e m i c a l a n d P h y s i c a l V a r i a t i o n s o f B u t t e r f a t ' on A b s o r p t i o n o f
D e f i n i t e Volumes o f Oxygen
Io d in e Ho.
0
10
41.7
4-0.4
41.3
2. 5
7.4
223.7
224.3
0
P e r o x i d e No.
Saponif.
No.
232.5
Free F a t t y Acid
R e i c h . - N e i s . Ho.
■ 50
0.93
C .9 1
**>uf * fr>n
1.02
r i ry
1 « v'
26 . 9
-
P o l e n s k e No.
0.90
R e f r a c tiv e Index
/ , jr. r
o
1.26
1.27
^
.t r ; r ' o
*i
.Co 0 8
lUO
250
500
39.4
38.7
36.8
38.9
fy,
O
37.3
rm
' ' •a
122.6
225,1
225,9
228 . 4
83 8 . 1
OK
D .
1.05
27.2
I.9S
1.15
1.4352
1 . 4 553
1.4558
P I n.k
Pink
Rod
Odor
Fresh
Fresh
F aint
Rancid
■Red
Rancid
3.2.
27.6
1.15
C©g .
Appenr&nc e
27.0
-
1.07
N r© is T e s t
Color
“J.T. *t-4
1000
<j
■
8. J
1.1
1.426
Rod
Purp
Ranc i d
F.r-.n : i
Y el lo v ; Velio;;; 2l e a c h e d R 1 e r.c he df: l e a c h e d D l c a c h e d 21 oa c '
No c h a .are
21
CRISCO
T h i s h y d r o g e n a t e d o i l w a s pui-cho.scd a t a l o c a l g r o c e r y
sto re.
The c o n t e n t s
perature
and - a h i l e
th ese co n d itio n s
of th e
still
of
c a n w e r e a l l o w e d t o m e l t a t a lov; t e m ­
liq u id
s am p les mere -vcighed o u t .
oxidr-bion a c t i v e
a f t or a p p ro x im a to ly tw enty h o u rs .
u c tio n period
Under
oxygen a b s o r p t i o n a t a r t o d
S tatic
c o n d i t i o n s g a v e an i n d ­
o f 14.17 m i n u t e s .
T a b l e XVII
The C h e m i c a l and P h y s i c a l V a r i a t i o n s o f C r i s e o on A b e o r p t i o n o f D e f i n . i t c V o lu m e s o f Cxy g c n
100
10
50
73.1
72.7
I C‘*->
f'J/ *11 . a
70 . 5
60.6
P e r o x i d e Uo,
C',4
2.3
14.9
3 O. 8
77.2
1 3 4 .4
S aponif. ho.
105.4
194.9
195.0
19 5 . 2
196.5
197.8
0
l o d i n o Uo,
300
200
1000
r- * ofi
OO
200.9
F r e e F a t t y Acid
0.06
0.07
0. 13
U. 16
0. 3 ],
0.61
1.46
X o i c h . - I v ' e i r . Uo.
ru*. r>n
0 . oo
0.32
0 . 36
0.54
0.37
I .-'17
O'. 19
0.20
0.23
C. 22
0.19
0.23
1 . 4 610 1 . 4 6 1 0 1 . 4 610 1.4'. 615
1.4620
!•'o l e n s k e Uo.
R e f r a c t i v e : I n d e x 1 . 4 610
X reis
Cdor
C olor
Test
1.4610
Peg.
r i nk
Pin]:
Vr e s h
fresh
Fresh
’' o c h an p; e
I XliK
ivod
ucn
R a n c i d R a n c i d Kano i d
J.1-.1j‘v•Cr-.•i
Dark c r .s<
Slouched
Purpl
' laac id.
OLIVE OIL
An a c t i v e
s ix hours*
oxygen a b s o r p t i o n s t a r t e d
a f t e r approxim ately
S t a t i c m e t h o d ga.ve a n i n d u c t i o n p e r i o d o f 400 m i n u t e s .
T a b le XVIII
The C h e m i c a l a n d P h y s i c a l V a r i a t i o n s
o f O l i v e O i l on A b s o r p t i o n o f
D e f i n i t e V o l u m e s o f Oxyg en
0
10
50
100
250
500
10 00
I o d i n e No*
85.4
85.5
83.7
83.8
83.1
81.1
77.7
P e r o x i d e Ho.
1 0 .4
14.9
35.2
42.8
76.9
130.3
236.6
S a p o i r i f . No*
192.1
192.6
193.1
192.9
194.7
194.2
198.9
Free F a t t y A cid
0.94
0.95
1.02
1.06
1.28
1.49
2.66
R e i c h . - M e i s , No.
0.14
0.15
0.14
0.21
0.25
0.66
1.46
P o l e n s k e Ho.
0 .18
0 . 2 1 . . 0.18
0.14
0.13
0.16
0.21
R efractiv e
In d e x 1.4 6 2 0 1 .4 6 2 0 1 .4 6 2 0 1.4621
1.4526 1.4627 1 .4 6 3 0
Neg.
Pink
Red
Red
Red
Odor
Fresh
Fresh
Fresh
Fresh
R ancid R ancid R ancid
C olor
Green
G reen
Green
Green
F a i n t I v B leached
A ppearance
Ilo n o t i c e a b l e d h n n g e
Red
Red
K reis T est
COTTONSEED OIL
Oxygen a b s o r p t i o n s t a r t e d a f t e r an i n d u c t i o n p e r i o d of
20 m i n u t e s .
S t a t i c m e t h o d g a v e a n i n d u c t i o n p e r i o d o f 56 m i n u t e s .
T a b l e XIX
The C h e m i c a l a n d P h y s i c a l V a r i a t i o n s o f C o t t o n s e e d o i l on A b s o r p t i o n
o f D e f i n i t e V o l u m e s o f Oxygen
0
10
50
111.9
112.2
P e r o x i d e No.
14.0
S a p o n i f . N o.
194.5
I o d i n e No.
1000
100
250
500
112.1
111.0
109.6
108,0
102.9
22.6
27.0
50.6
71.8
174.8
326.9
194.2
195.1
195.4
195.0
196.7
200.6
F ree F a t t y A cid
0.11
0.12
0.27
0.23
0.30
0.45
1.07
R e i c h . - M e i s . No.
0.35
0.49
0.47
0.41
0.54
0.75
1.45
P o l s n s k e No.
0 . IS
0.22
0.23
0.24
0.19
0.19
0.22
R e f r a c t xvo I n d e x 1 . 4 6 6 2 1 . 4 6 6 2 1 . 4 6 6 2 1 . 4 6 6 4 1 . 4 6 6 5 1 . 4 6 7 0 1 . 4 6 0 0
Purple P urple
K rais Test
Pink
Pink
Red
Re d
Red
Odor
Fresh
Fresh
F aint
Faint
Rancidi R ancid Rancid
C olor
Appearance
D a r k e r D a r k e r Darke: s t L i g h t e r L i g h t e r B l e a c
No n h a n g e
LIHSEED OIL
Oxygen a b s o r p t i o n s t a r t e d
u ctio n period.
S tatic
a f t e r l e s s t h a n one h o u r i n d ­
c o n d i t i o n s g a v e a n i n d u c t i o n p e r i o d of 1 0 4 . 5
m inutes.
T a b l e XX
The C h e m i c a l and P h y s i c a l V a r i a t i o n s o f L i n s e e d O i l on A b s o r p t i o n
o f D e f i n i t e Volumes o f
0
I o d i n e Uo.
10
50
Oxygen
100
250
500
1000
181.3
181.6
181.1
178.7
178.9
176.7
170.0
P e r o x i d e Do.
4.1
15 .3
20.5
30 .4
53.2
107.6
222.4
S a p o n i f . Ho.
191.1
189.7
191.9
192.3
193.3
194.1
197.9
F ree F a t t y A cids
3.29
2 .3 7
2.30
2.3 7
2.70
3.10
3.97
R e i c h , - I e i s . Mo.
0.04
0 .1 1
0.16
0.2 0
0.35
0.56
1.50
P o l e n s k e Mo.
0.07
0 .0 8
0.10
0.0 8
0.07
0.09
0.20
R e f r a c t i v e I n d e x 1 . 4 7 3 9 1 . 4 7 4 0 1 . 4 7 4 3 1 . 4 74-5 1 . 4 7 4 6 1 . 4 7 4 7
1.4750
K reis Test
Meg.
Pink
Red
Red
Red
Odor
Fresh
Fresh
T aint
T ain t
Rancid. Rancid
Appearance
Mo n o t i c e a b l e C h a n g e
Red
Rod
Ranci
A ll r e s u lts in d ic a te th e re is a d e f in ite change occurring
i n a f a t upon a b s o r p t i o n o f o x y g e n .
The s h o r t e r i n d u c t i o n p e r i o d s
o f e a c h f a t i n c o m p a r i s o n t o t h o s e o b t a i n e d by t h o s t a t i c method
a r e due t o t h e i n c r e a s e d s u r f a c e e x p o s e d t o oxygen d u r i n g s t i r r i n g .
A s t u d y o f t h e r e s u l t s shows i n a l l c a s e s a n i n c r e a s e
i n s a p o n i f i c a t i o n number due t o t h e f o r m a t i o n of f a t t y
r i c i d s o f low­
e r m o l e c u l a r w e i g h t , a d e c r e a s e i n i o d i n e number due t o
o f t h e d o u b l e bo nds p r e s e n t i n t h e f a t ,
a re m o v a l
an i n c r e a s e i n p e r o x i d e num­
b e r due t o t h e f o r m a t i o n o f p e r o x i d e s d u r i n g o x i d a t i o n ,
in free f a t t y
an i n c r e a s e
a c i d number due t o f o r m a t i o n o f f r e e f a t t j r a c i d s , an
i n c r e a s e i n R e i c h e r t - I l e i s s l number due t o f o r m a t i o n o f v o l a t i l e
u b l e f a t t y a c i d s , a n i n c r e a s e i n P o l e n s k e number due t o
form ation
o f v o l a t i l e i n s o l u b l e f a t t y a c i d s , an i n c r e a s e i n r e f r a c t i v e
a n i n c r e a s e i n t h e c o l o r o f t h e K r e i s t e s t due t o t h e
sol­
index,
f o r m a t i o n of
e p ih y d r in a ld e h y d e , th e appearance of a r a n c id odor w h i c h in c re a s e d
i n i n t e n s i t y and a b l e a c h i n g o f t h o p i g m e n t s p r e s e n t i n
a fat0
A g ra p h ic study of th e s a p o n i f i c a t i o n num bers of n i l th o se
f a t s w i t h r e s p e c t t o t h e a b s o r p t i o n o f oxygen shows t h e
same g e n e r a l
p a r a l l e l i n c r e a s e i n tho p ro d u c tio n of a c id s of lower m o lo c u la r
w eight.
The l a r g e f a t m o l e c u l e s have be en decomposed t o
c h a i n m o l e c u l e s many of w h ic h a r e a c i d s .
small sh o rt
Since b u t t e r f a t be fo re
o x i d a t i o n c o n t a i n s s. l a r g e number o f s h o r t c h a i n f a t t y
acids,
it
i s t o be e x p e c t e d t h a t i t s i n i t i a l s e p o n 1T i e a t i o n n u m b e r us w e l l us
t h e s n p o n o f i c a t i o n numbers o f t h e o x i d i z e d b u t t e r f a t w i l l bo much
h i g h e r t h a n t h e o t h e r f a t s and o i l s .
!'o c o r r e l a t i o n o f
saponific­
a t i o n number w i t h ICrais t e s t c o l o r a t i o n arid r a r . c i d o d o r may be
noted.
120
I o d in e numbers o f t h e f a t s
and o i l s
d ecrease w ith a b s o r p tio n of oxygen.
of K reis t e s t
shov< t h e
There i s
same g e n e r a l o a r a l l e l
no a p p a r e n t c o r r e l a t i o n
c o l o r a t i o n and r a n c i d o d o r v /ith I o d i n e number.
The f a t s
and o i l s
show a m or e p r o n o u n c e d v a r i a t i o n
o x i d e n u m b e r s w i t h oxygen a b s o r p t i o n .
peroxides are p re s e n t in
D u r i n g t h e a b s o r p t i o n m ore
oxidized cottonseed o i l than th e
and o i l s .
B u t t e r f a t c o n ta in s le s s p erox ides than th e
olive
crisco ,
o il,
linseed
o il
oxide number w i t h K r e i s t e s t
show t h e
seed oi]
o il,
other f a ts
oth ers.
same g e n e r a l t r e n d i n p e r ­
acids of th e f a ts
and o i l s
i n c r e a s e w ith in c r e a s e d oxygen a b s o r p t i o n .
and c r i s c o y i e l d
Lard,
c o l o r a t i o n and r a n c i d odo r i s a p p a r e n t .
Th e p r o d u c t i o n o f f r e e f a t t y
shows a p a r a l l e l
of p e r ­
approxim ately th e
seme r e s u l t s w h i l e o l i v e
l o r d a n d b u t t e r f a t may b e c l a s s i f i e d t o g e t h e r .
a lth o u g h y i e l d i n g an increa.se s i m i l a r to th e
C otton­
others
Linseed o i l
is
o f much h i g h e r
value.
A ll f a ts
and. o i l s
s h o w e d t h e same g e n e r a l i n c r e a s e
Re i c h e r t - l i e i s s 1 n u m b e r w i t h i n c r e a s e d o x y g e n a b s o r p t i o n .
showed muc h h i g h e r r e s u l t s
in itially
h ig h er.
throughout th e
A ll o th e r f a ts
in
nut ton* at
a b s o r p t i o n sanco i t wrs
sho wed a p p r o x i m a t e l y t h e so.mo
resu lts.
The P o l o n s k e n u m b e r o f t h e v a r i o u s f a t s
w id e r v a r i a t i o n w i t h oxygen a b s o r p t i o n .
of th o most v o l n t i l o
shown on a b s o r p t i o n
of th e
least
in so lu b le
fatty
of oxygen " l i i l e
amount o f v o l a t i l e
snowed a n u c n
J-ar d s how e d t h o p r e s e n c e ,
a cid s v ix h very l i t t l e
b u t t e r f ax snowed t o o p r o onco
in so lu b le i •
C o tto n s e e d o i l and c r i s c o
m crca..^
sho wed t h e
sane d i g a t
during a b s o r p tio n w h ile
o live
o il
shoved a n a r k e d d e c r e a s e fo llo w e d
by a n i n c r e a s e v / i t h o x y g e n a b s o r p t i o n .
e s t p r o d u c t i o n of v o l a t i l e
A ll o ils
fractiv e
Linseed o i l
in so lu b le fa tty
and f a t s
shoved th e
acids.
sane s l i g h t in c r e a s e
Index w ith oxigen a b s o r p tio n .
e s t v a l u e s f o l l o w e d by c o t t o n s e e d
sho wed t h e g r e a t ­
Linseed o i l
o il,
o live o il,
i n Re-
shoved t h e h i g h ­
crisco,
l a r d and
b u tto rfat.
A study of
the
o x id atio n
the
resu lts
c o n p o s ilio n of th e f a t s
o f f e r s no c l u e
o b ta in e d w ith th e oeroxidc
to
w hen.
Th e i o d i n e n u n b o r o h o v s no c o r r a l a t a b l e c h a n g e s d u r i r - ~
o x id a tio n w ith respect' to the
apparent
the
c o rre la tio n of fre e
fats is
crt-Iicissl
catio n .
observed
con” o s itio n of th e v a rio u s f a t s .
fatty
a c i d n u n b o r w i t h eorv’- o c i t i c n
d u ring o x id a tio n , i b i s
holds tru e
number, l o l c n s k o number, R e f r a c t i v e
T h e s e r e c u '1i s
f a t absorb
a 1 1 c 1 ff.shd.on. no r e o r l e s s
I n d e x and S a p o n i f i ­
in each
s i . a p l / e r - p r o d u c t - : i n r. rr r -
i r r o s n e o t i v o o f i•{• ' •; r-
V
'1 r - r- •’ fsi":
d
4
lucati.t i c s. o f o l x ’i c ,
r,
7
.1
* j - !- 4 -
•)
li'n o lc .ic
..
r* ^
oddrs a t
1 0 0 ml o x y g o n ribs o r
relativ e
p e r c e n t ages
riore
highly
c o n 7 , - ~ ; L n
an
o f
m
e
produce
olive
aid
n o r c -
n
a rancid
is
r 1 f i .*•'
of o lcic
unoniurxtod
: •*
and l i n o I o n :
■’ i s - '
a s iI dd -e- ..
m
e 'e r
c o s c a h
acid
o
[■
at
-■
>'■.
ta
v
^ h -
c
r"
'■
-
d l G .
-
‘, 5 1 n l z
of
fo r h rich -
In d ic a te the u n v ,lu r r ie d f a t J y -c id s
o x v g e n °n*l b r c *1; ^ov.r. i n t o
iTo
t ?
n r
■"!
\
J
l i n n
^
r- r '
y
- • , « --
■ ■ ;* " f ; f g
-
y
r
v-.-• -
-
- -
c ' - - -
-
i i --
-
r e d
• -
•*
o . y " f n a ' r:c r y so'" .
1 r i x k c ' 1 by t h e
(’
ciorieiic
/
.>
" I"
.
responsible th a n lin o le ic
a nd l i n o l e h i c
acids in the production
of a r a n c i d o d o r.
I n t h i s v/orl; a l l f a t s
t h e same d e f i n i t e
fo r com parison.
a n d o i l s -acre a l l o w e d t o a b s o r b
volum es of oxygen.
T h i s g a v e a.
definite, b a sis
A l l r e s u l t s w e r e c o n t r o l l e d p r i m a r i l y by t h e i n i t ­
i a l com position of th e
fresh f a t.
Upon o x i d a t i o n e a c h c h e m i c a l o r
p h y s i c a l c o n s t a n t was a l t e r e d i n a c c o r d a n c e w i t h t h e p r o d u c t i o n of
th at in d iv id u al co n stitu en t.
The d o u b l e b o n d s i n t h e u n s r . t u r a t e d
g ly c e r id e were d e s tr o y e d w ith th e
The p e r o x i d e s
decomposed t o form a ld e h y d e s and a c i d s o f low er m o le ­
c u la r w eight.
atile
subsequent p ro d u c tio n of peroxides
Free f a tty
and n o n - v o l a t i l e
a c i d s w e r e p r o d u c e d a s w e l l a s m ore v o l ­
a c i d s and s o l u b l e o r i n s o l u b l e
( in w ater)
acid s.
I t may b e r e a d i l y n o t i c e d t h a t e a c h i n d i v i d u a l v a l u e i s
v/orth v e ry l i t t l e
as a c r i t e r i o n
degree of o x id a tio n ,
th ere
is
of r a n c i d i t y
h’i t h t h e e x c e p t i o n o f t h e p e r o x i d e v a l u e t
no g r e a t d i f f e r e n c e b e t w e e n t h e c o u s t r . n t s f o r t h e f r e s h
f a t and t h e f a t w h ic h h a s a b s o r b e d one l i t e r
the
o r as an in d e x of t h e
fresh fa ts
oxide v a lu e s
and even t h i s
o f oxygen,
them selves w i l l v ary w ith in t h i s
a p p e a r t o be t h e m ost r e l i a b l e
one g i v e s o n l y a r e l a t i v e
of the o x id a tio n .
range.
many o f
The p e r ­
c o n sta n t of o x id a tio n
in d ic a tio n of th e extent
SUMMARY
I t was fou n d t h a t t h e
in d u c tio n p e r io d o f la r d i s
d ou b led f o r
e a c h n i n e d e g r e e s r e d u c t i o n i n t e m p e r a t u r e w h i c h w o u ld i n d i c a t e
a c h e m ic a l r e a c t i o n d u r in g t h i s
p erio d
o f supposed i n a c t i v i t y .
T h i s r e a c t i o n may i n v o l v e t h e p r e f e r e n t i a l o x i d a t i o n o f t h e
a n tio x id a n ts b efo re th e f a t i s
attack ed ,
A r a n g e o f o n l y 1 0 0 mm. b e l o w a t m o s p h e r i c p r e s s u r e c o u l d b e o b ­
t a i n e d an d w i t h i n t h i s r a n g e no v a r i a t i o n o c c u r r e d .
a ffects
o x id a t io n o n ly i n
so f a r as i t
o f oxygen in to th e f a t w ith r e sp e c t to
The a d d i t i o n o f t h e
carbon c o n te n t t o
is
crease in step s
w e ig h t.
c o n tr o ls th e d iffu s io n
its
so lu b ility .
s a t u r a t e d s t r a i g h t c h a in a c id s o f even
l a r d p r o d u c e s an u n p r e d i c t e d e f f e c t
in d u c tio n p erio d o f th e la r d .
c u la r w e ig h t
P ressu re
o b ta in e d .
of six
T h is v a r i a t i o n
on t h e
No l i n e a r v a r i a t i o n w i t h m o l e ­
In stea d th e in d u c tio n p erio d s d e­
c a r b o n a to m s w i t h i n c r e a s e d m o l e c u l a r
o f th e in d iv id u a l a c id s
s t o o d b u t a p p e a r s n o t t o b e due t o
is
n ot under­
a r e a c t i o n b etw een th e
a d d e d a c i d and t h e a n t i o x i d a n t s a s o b s e r v e d f r o m a s t u d y o f
a lc o h o l e x tr a c te d
l a r d and t h e o x i d a t i o n o f t h e p u r e s a t u r a t e d
a cid s .
F a t s may b e s a f e l y
d iffu sio n
s t o r e d i n n it r o g e n but i n carbon d io x id e
o f t h e g a s w i t h t h e f a t t a k e s p l a c e f o l l o w e d by an
a p p a r e n t r e a c t i o n r e s u l t i n g i n an o f f - o d o r .
On t h e a b s o r p t i o n o f d e f i n i t e v o l u m e s o f o x y g e n f a t s
show p r o g r e s s i v e
and o i l s
c h a n g e s i n t h e i r p h y s i c a l and c h e m i c a l c o n s t a n t
T h e s e r e s u l t s may b e u s e d t o
th e
c o r r e la te
ch a n g es w h ich o ccu r in t h e
fa t
o x y g en co n su m p tio n w it h
d u rin g o x i d a t i o n .
BIBLIOGRAPHY
Bach
(1897)
C o m p t. r e n d . 1 2 4 9 5 1 , C i t e d by M i l a s .
B fic k s tr iJ m , H. L , J ,
(1 9 2 7 )
J . Am* Chem . S o c . 49 1 4 6 0 - 1 4 7 2 .
von B a e y e r , A , and V i l l i g e r , V .
(1900)
B e r , j33 1 5 6 9 ,
c ite d
by M i l a s .
B a i l e y , K, C . ,
(1 9 3 0 )
J . C hem . S o c . ] 0 4 - 1 1 6
B a lla n ty n e
(1891)
J . S o c * Chem , I n d , 1 0 29
B a ly , E , C, C,
(1912)
J * S o c . Chem , I n d , <3 1 5 1 5 - 5 1 8
B a n k s , A . and H i l d i t c h ,
(1932)
J.
T. P.
S o c . Chem. I n d . 5 1 4 1 1 - 4 1 4 T
B a r n i c o a t , C. R.
(1 9 3 0 )
D ep t. S c i .
(1931)
J,
I n d . R e s e a r c h , R e p t. Food I n v e s t .
B o a rd 3 8
S o c . Chem. I n d , 5 0 3 6 1 - 5 T
B e ilste in
(1893)
C i t e d b y H e p b u rn
B erth o let
(1855)
J . pharm . ch im . 27 9 6 ,
c ite d
b y H epb u rn
B etter, E. I.
(1 9 3 3 )
S e ife n s ie d e r -Z tg .
27 3097*
60 2 0 0 - 2 ,
2 1 9 -2 1 ,
2 3 5 - 7 , Chem. A b s .
B e v is,
J . F.
(1923)
J . S o c . C hem . I n d . 4 2 4 1 7 - 4 2 0 T
B ir g e , R. T .s e t a l
(1 9 2 6 )
B u ll.
N a t . R e s e a r c h C o u n c i l 11 ( I I I )
69
(1926)
Brow ne, C. A .
(1899)
J . Am. C hem . S o c .
(1 925)
21 6 1 2 , 8 0 7 ,
975
I n d . E b g ^ .C h e m . 1 7 4 4 - 4 7
B r u n n e r , M.
(1927)
H e l v * C h im . A c t a 1 0 7 0 7 - 7 2 8 ,
c ite d
by M ila s
C h r is t ia n s e n , J . A.
(1924)
J . P h y s . C hem . 2 8 1 4 5
(1928)
T ra n s. Faraday S o c .
24 7 1 4 -5
C o e , M. R .
(1938)
O i l & Soap 15 2 3 0 -6
C o b , M, R . an d L e C l e r c , L . A .
(1934)
C o ffey ,
I n d . E n g . C hem . Z6_ 2 4 5 - 8
Sam uel
(1921)
J* Chem . S o c .
119 1 4 0 8 -1 5
D a k in , H. D.
(1921)
P h y s io l. R evs.
1. 3 9 4 - 4 2 0
( 1 9 2 1 ) , C hem . A b s .
17 1036
D a v i e s , W. L .
(1 9 2 8 )
J.
S o c * C hem . I n d * 4 7 1 8 5 - 7 T
(1928a)
I n d . C h e m ist ±
(1 930)
O il & Fat
(1931)
Food T e c h .
269-72
I n d u str ie s
1_ 1 4 1 - 3 ,
(1 9 2 8 ),
1_ 4 2 7 - 3 1 ,
1 8 1 -3 ,
Chem. A b s .
22 4 2 6 3
453-7
2 6 9 - 7 0 , Chem . A b s . 2 7 1 9 5 1
D e a t h e r a g e , F . E* a n d M a t t i l l , H , A ,
(1 9 3 9 )
I n d * E n g . Chem. .31 1 4 2 5 - 1 4 3 1
D i x o n , M.
(1927)
Proc* R oy. S o c.
(1929)
B io l.
(L o n d o n )
R ev. 4 352
1 0 IB 5 7 - 7 0 ,
(1 9 2 9 ),
c ite d
by M i l a s .
c i t e d by M i l a s .
D u c la u x
(1888)
C i t e d b y H epb u rn *
D u n la p a n d S h e n k
(1903)
E llis ,
J . Am. Chem. S o c .
2J5 8 2 6
G . W.
(1926)
J.
S o c . Chem. I n d . 45. 1 9 3 - 9 T
E m e r y , J . A , an d H e n l e y , R .R .
(1922)
I n d . E n g . Chem.
14 9 3 7 -4 0
E n g l e r , C . and W e is s b e r g , J .
(1898)
E n g le r ,
B er.
31
3046
C . an d W i l d
(1897)
B er.
30 1669
F a h rio n
(1893)
Z . a n g e w . Chem. 1 7 1 - 1 7 3 , C h e m . - Z t g .
c ite d
F r e n c h , R« B . ,
(1935)
G affron ,
1£ 4 3 4 -6 ,
by H e p b u r n .
Q c o t t , H» S . a n d M a t t i l l ,
H. A .
I n d . E n g . Chem. 2 7 7 2 4 - 7
H*
(1926)
B io c h e m . Z . 179 1 5 7 - 8 5 ,
c i t e d by C oe.
(1927)
B er.
by C o e .
6 0B 2 2 2 9 - 3 8 , c i t e d
1848,
G ardner, H. A.
(1914)
I n d * E n g , Chem, _6 9 1
G reenbank, G, R,
(1936)
O i l & Soap 13 1 4 0 - 1
G r e e n b a n k , G , R , an d H o lm , G , E ,
(1924)
Ind.
Eng.
Chem . 1 6
598-601
(1925)
Ind,
Eng.
Chem . 1 7
625
(1930)
In d . Eng.
Chem. ( A n . )
(1 9 3 4 )
Ind0 Eng.
Chem. ,26
G r e ttie ,
2 9 -1 0
243-5
D . P . and N ew ton , R. C.
(1931)
I n d . E n g . Chem.
(A n .)
3_ 1 7 1 - 3
G rQ ger
(1888)
Z . a n g e w . Chem. 6 2 ,
H a m i l t o n , L . A . an d O l c o t t ,
J.
S o c . Chem. I n d . 2 0 2 .
H. S .
(1936)
O i l & Soap 13 1 2 7 - 9
(1937)
I n d . E n g . Chem. 29 2 1 7
H an u s
(1900)
Z . U n t e r s u c h . N a h r . G e n u s s . J3 4 3 2 ,
c ite d
by H epburn
H a r r is, J . P.
(1923)
H epburn, J .
(1910)
Chem. M e t . E n g . J29 93
S.
J . F r a n k lin I n s t ,
1 6 8 36 5 - 8 4 ,
1 6 8 4 2 1 - 5 6 , JL69 2 3 - 5 4
H i l d i t e h , T . I ) . 1 an d S l e i g h t h o l m e , J . J .
(1932)
J.
S o c . Chem. I n d . _51 3 9 - 4 4 T
H o lla n d , E . B .
(1918)
J . A g r . R e s e a r c h J13 3 5 3 - 6 6
(1918)
Holm* G . E . and G r e e n b a n k , G. R.
(1 9 2 3 )
In d . Eng.
Chem. 1 5 1 0 5 1 - 3
(1 924)
In d . Eng.
Chem* 1 6 5 1 8
(1933)
In d . Eng.
Chem.
25 1 6 7 - 8
H o lm , G. E . , G r e e n b a n k , G. R . and D e y s h e r , E . F .
(1 9 2 7 )
In d . Eng.
Chem.
19 1 5 6 - 8
H y l a n d , J* an d L l o y d , LL
(1 9 1 5 )
J . S o c . Chem . I n d , 3|4 6 2 - 5
I n g l e , H.
(1913)
J . S o c . Chem. I n d .
32, 639
J a k im e n k o
(1 901)
Z . U n t e r s u c h . N a h r . G e n u s s . 4. 9 7 5 , c i t e d
J o n e s , T . W.
(1 9 2 4 )
C h e m i s t r y a n d I n d u s t r y 43 1 2 5 8 - 9
K e r r , R* H.
(19 1 8 )
I n d . E n g . Chem. _10 4 7 1
(19 2 1 )
C o tton O il P r e ss £ 4 5 -8
K e r r , R . H . and S o r b e r , D . G.
(19 2 3 )
I n d . E n g . Chem. _15 3 8 3 - 5
K i n g , H . H.
(19 1 5 )
I n d . E n g . Chem.
502
K o b e r t , K.
(19 0 7 )
Z . a n a l . Chem. 4 6 7 1 1 - 1 4
K u f f e r a t h and M e r c h e n s
(19 0 4 )
Z . a n g e w . Chem. 1 J. 1 0 9 5 - 7 , c i t e d by C o e .
(19 0 5 )
A n n . P h y s i k JL6 6 6 7 ,
c i t e d by
C oe.
by H e p b u rn .
L a m p e t t , L . H . an d S y l v e s t e r ,
(1931)
N. D.
C h im ie f t I n d u s t r i e
(S p . N o .)
6 4 2 - 7 , Chem. A b s . 2JS 3 7 3 7
L a n g b e in and S ta h lm a n
(1 890)
J . p r a k t . Chem. 4 1 .
c ite d
by P o w i c k .
L ea , C. H.
(1928)
J.
Chem . S o c . 1 5 7 7
(193D )
D ep t. S c i.
Ind* R e s e a r c h , R e p t . Food
(1 931)
P r o c . Roy*
S o c * (L o n d o n ) 108B 1 7 5 - 1 8 9
(1933)
J . S o c . Chem. 5 2 1 4 6 - 9 T
(1934)
I n d . E n g . Chem*
(1935)
D ep t. S c i.
3 4 -8 ,3 8 -4 3
(A n .)
I n v e s t . Board 3 0 - 7
6, 2 4 1
I n d . R e s e a r c h , R e p t . F oo d
I n v e s t . Board 1 934
(1935)
L e a , C. H. and H i l d i t c h , T . D .
(1928)
J * C hem . S o c * 1 5 7 6
L lo y d , L . L .
(1 927)
J . T e x tile
I n s t . JL8 5 1 7 - 9 T , Chem. A b s . 22 2 0 7 3
L u t h e r , R0
(1903)
M a ttill,
Z . p h y s i k . Chem. 4J5 6 6 2 ,
H. A .
(1931)
J . B i o l . Chem. 9 0 1 4 1 - 5 1
M a t t i l l , H. A . and C ra w fo r d , B .
(1930)
M ila s,
c ite d
I n d . E n g . Chem. _22 3 4 1 - 4
N. A .
(1 929)
J.
P h y s . Chem. 3J3 1 2 0 4 - 1 6
(1930)
J . Am. Chem. S o c .
5J2 739
by M i l a s .
131
M ila s, N. A.
(1932)
Chem. R e v . 1 0 2 9 5 - 3 6 4
(1934)
J . P h y s . Chem . 3 8 4 1 1 - 1 8
M o u r e u , C« a n d D u f r a i s s e , C*
(1926)
Chem . R e v . 3. 1 1 3 - 6 2
. M u llik e n
(1 925)
P h y s . R e v . 26 5 6 1 - 7 2
N e u , R*
(1933)
N ic o le t,
I n d . E n g . Chem. 8. 4 1 6 - 7
H. S .
(1934)
O lc o tt,
3 0 5 8 3 - 8 , Chem. A b s . 2 8 2 2 0 5
B . P . a n d L i d d l e , L . M.
(1916)
O lc o tt,
A llg e m , O e l-u F e t t - Z t g .
J . Am. Chem . S o c . J56 2 4 9 2
H . S . an d M a t t i l l ,
H. A .
(1936)
J . Am. Chem . S o c .
58 1 6 2 7 -3 0
(1936a)
J . Am. Chem. S o c .
58 2 2 0 4 - 8
P o o l , W. 0 .
(1931)
O i l 8: F a t I n d u s t t r e s 8, 3 3 1 - 6
P o w i c k , W. C .
(1 9 2 3 )
(1923a)
P r itz k e r , J .
(1928)
R e iff,
J . A g r . R e s e a r c h J26 3 2 3 - 6 2
I n d . E n g , Chem. JL5 66
and J u n g k u n z , R .
S e l f e n s i e d e r - Z t g . J54 9 4 6 , Chem. A b s . _22 3 0 5 7
0 . M.
(1 926)
J . Am. Chem. S o c . 4 8 2 8 9 3 - 9
132
R id e a l, E . K.
(1 928)
T rans* F arad ay S o c ,
24 571
R itse r t
(18 9 0 )
N a t u r e , W o c h s c h r , .5 3 3 1 , 3 4 3 , 3 5 4 , 3 6 4 , 3 7 4 , c i t e d by H e p b u rn .
R o sc h e n , H, L , and N ew to n , R, C,
(1 9 3 4 )
O il & Soap 11 2 2 6 - 8 , 2 3 6 -8
R o y ce, H, D.
(1 9 3 1 )
S o a p -7 2 5 - 7 ,
38
R u e m ele, T h .
(1 9 3 4 )
S e i d e n s i e d e r - Z t g . 63. 1 2 5 , Chem. A b s . .28 3 2 5 7
S a lk o w sk i, E
(1 9 1 9 )
Z . U n t e r s u c h , N a h r , G e n u s s , .34 3 0 5 ,
Chem. A b s . JL4 7 8 5
S a lw a y , A . H,
(1 916)
J . Chem. S o c .
109 1 3 8 -4 5
S c a la , A.
(1 8 9 7 )
C it e d by H ep b u rn .
(19 0 8 )
C i t e d b y N i c o l e t an d L i d d l e .
Scherer
(1795)
S k e llo n ,
J.
(1 931)
C i t e d by H e p b u rn
H.
J . S o c . Chem. I n d .
50 3 8 2 - 6 T
S m i t h , H. L .
(19 1 5 )
P arm . J .
9.5 4 - 5 ,
Chem. A b s . 9. 2 7 1 6
S m i t h , W. B .
(1920)
I n d . E n g . Chem. .12 7 6 4 - 6
SoxhjpSt
(1 8 8 5 )
C i t e d by H epburn
S p a eth
(1 8 9 6 )
Z* a n a l . Chem . 3,5 4 7 1
S t o k o e , W. N .
(1921)
T a ffe l,
J . S o c . Chem . I n d . 4 0 7 5 - 8 1 T
A . and R e v i s , C .
(1 9 3 1 )
J.
S o c . Chem. I n d .
5 0 87 T
T f t u f e l , K . aj*d C e r e z o , J .
(1927)
C hem . A b s . 2 2 1 7 5
T ftu fe l, K . and M ttlle r , J .
(1 9 3 0 )
C hem . A b s . J25 3 8 5 7
T a y lo r , H. S .
(1923)
J.
P h y s . C hem . 2 7 3 2 2
T ito ff
(1903)
Z . p h y s i k . C hem . 4b 6 4 1
T r i e b o l d , H$ 0 .
(1931)
C e r e a l Chem. j3 5 1 8 - 3 0
T r ie b o ld , H. 0 .
(1 9 3 2 )
T r ie b o ld ,
C e r e a l C hem . 9. 5 0 - 6 4 ,
H. 0 . ,
(1 9 3 3 )
an d B a i l e y , C . H .
W ebb, R . E .
91-106
and R u d y , W. J .
C e r e a l C hem . 1 0 2 6 3 - 7 6
T s c h ir c h , A.
Chem . U m schau .32 2 9 - 3 1
(1925),
T s c h i r c h , A . and B a r b e n , A .
(1924)
Chem . A b s .
18 2970
c ite d
by P o w ic k .
134
W a g n e r , H . , W a l k e r , R . a n d O e s t e r m a n n , H.
(1 9 1 3 )
W h eeler,
Z . U n t e r s u c h . N a h r , G en u ssm . .25 7 0 4 , Chem, A b a , J7 3 6 7 5
D, H,
(1932)
W ie la n d ,
O i l & S o a p 9. 8 9 - 9 7
H.
(1912)
B e r , .45 4 8 4 - 9 3 ,
(1913)
B e r , 46 3 3 2 7 -4 2
(1914)
B e r . 47 2085
6 8 5 -7 ,
2600-5
W in c k e l
(1905)
Z , U n t e r s u c h . N a h r . G e n u ssm . £
Y a m a g u ch i, B .
(1931)
Chem. A b a . 2 6
863
(1932)
Chem. A b s . 2 7
201
90
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