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Патент USA US2131160

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Sept-.27, 1938-
s. z. AVEDIKIAN
'
2,131,160
TOBACCO AND METHOD OF TREATING TOBACCO
Filed March so, 1935
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Sept. '27, 1938’.
s. z. AVEDIKIAN
2,131,160
TOBACCO AND METHOD OF TREATING TOBACCO
Filed March 50, 1935
2 Sheets-‘Sheet 2 _
a“v?im
‘INVENTOR _
ATTORNEY8,
2,131,160
Patented Sept. 27, 1938
* UNITED ‘STATES,’ ,
PATENT OFFICE
_2',1's1,1eo
TOBACCO AND METHOD OFv TREATING
' 'ronaCCO
'
Souren Z. Avedikian, New York, N. Y.
Application March 30,1935, Serial No. 13,837
19 Claims. (C1. l3le55)
This invention relates to improvements in
method of. treating tobacco and to improvements
in smoking tobacco as an article of manufacture.
This invention relates especially to improvements
. 5 in the color and burning properties of smoking
tobacco and to novel methods whereby improve
ments of this character may be achieved.
It is a purpose of this invention to bleach to
bacco so that its color is made more attractive
10 and in such a manner that the ?avor and aroma
of the tobacco is not impaired. Many tobaccos of
that the term "oxide of nitrogen" as used herein
includes NO mixed with some oxygen or any
other oxide of nitrogen or mixtures thereof. Ox
ide of nitrogen may be used alone, but‘is pref
erably employed in combination with other gases
such as oxygen, nitrogen, air, carbon dioxide, car
bon monoxide, argon, neon, helium, and other
similar inert gases, inert in the sense that their
function is merely to act as diluents, and not, in
any other way, in?uence the bleaching process
nor interfere with the action of oxides of nitrogen
desirable ?avor and aroma are of an undesirably
on cured, tobacco, or mixtures thereof.
dark and dirty color which makes them undesir
found that oxide of nitrogen brings about the
able for use except in the lower grades of smok
desired bleaching of the tobacco so as to produce
from tobacco which is dark and dirty a tobacco 15
which has a very pleasing and uniform light color.
I5 ing tobacco products.
Leaves of a light brown
and pleasing color suitable for wrappers in mak
ing cigars and the like, are costly at the present
time. Heretofore, attempts have been made to
bleach tobacco with bleaching agents of various
20 types so that dark colored tobaccos could be used
as wrappers for cigars. However, such attempts
have not been successful due primarily to the fact
that the bleaching treatments employed have re
sulted in such undesirable effects as impairment
25 in the ?avor and aroma of the tobacco, impair
I have
Any degree of bleaching from a slight lightening
in color to extremely pale effects can be effected
accordingto the process of this invention. Pref
erably," the bleaching is conducted until the to
bacco leaves are of a medium to light brown color.
Leaf tobacco bleached according to this inven-’
tion is particularly desirable in making cigar
wrapp'ers.
,
_
-
The tobacco may be bleached in the practice of
ment of the texture of'the tobacco so that it is , this invention after the tobacco has ?rst been
excessively brittle and impairment of the burning cured. In curing tobacco, green tobacco is sub
properties of the tobacco. If attempt is made to jected to controlled conditions of temperature and
moisture to develop ?avor and aroma by fermen
apply the methods of bleaching heretofore em
30 ployed with less severity so as to preserve to‘ tation and bacterial actions which proceed dur 30
greater degree the ?avor, aroma, texture and ' ing the curing process. Certain chemical treat
ments to effect or aid in curing have also in
burning qualities of the tobacco; then the bleach
ing action, is too slight to be bene?cial and is certain instances been resorted to. During the
likely to be only temporary in character. While curing of tobacco, the green chlorophyll in the
35 bleaching of tobacco has been regarded as desir - leaves becomes brown and the tobacco frequently
becomes of a dark, dirty and unpleasant color as
able for many years, it is not employed commer
cially for reasons including those’ above men-_ referred to above. As distinguished from the
curing of tobacco, this invention is directed to
tioned.
.
It is a further purpose of this invention to the problem of improving the color and burning
40 improve the burning properties including the rate characteristics of tobacco. It is preferable to cure
of burning of the tobacco and the color of the tobacco before it is treated and improved ac
ash. Further purposes of this invention relate cording to this invention. After the tobacco has
to improving upon the texture and quality of the been brought to desired ?avor and aroma by our
ing according to a variety ‘of known methods, I
It is one of the features of this invention that have found that its color and burning character
45
istics can be improved according to this invention
the bleaching agent employed to bleach the to
bacco comprises one or morev oxides of nitrogen. without impairment of its ?avor and aroma.
While the exposure of tobacco to an oxide of
Preferably nitrogen trioxide (N203) .is- used as,
the bleaching agent. Other oxides of nitrogen nitrogen to effect substantial bleaching of tobacco
such as N02 and N204 may also be employed, is an important feature of this invention, further,
however. Pure NO is not regarded as a desirable features of this‘invention relate to the treatment
bleaching agent, but when oxygen vas from the of the tobacco prior to such bleaching step, the
control of conditions during the bleaching step,
air is mixed therewith as in converting the sub
3 stance to N203, N02 OI‘,N204, then it becomes a and the treatment of the tobacco following the
55 desirable bleaching agent. It is to be understood ‘ bleaching step. Thus, in. bleaching tobacco us 65
tobacco.
-
T
‘
-
2,131,100
ing an oxide of nitrogen according to this inven
tion, the tobacco should be in a moistened condi
tion. If attempt is made to bleach tobacco with
an oxide of nitrogen while the tobacco is dry and
5 in an atmosphere which is so dry tobacco cannot
absorb a substantial amount of _moisture there
from, extremely poor or no bleaching effects re
sult. If the tobacco contains a substantial
amount of moisture the bleaching action of the
10 oxide of nitrogen in the bleaching operation is
rendered much more effective. Moreover, the
atmosphere in which the bleaching is conducted
should also contain a relatively high proportion
of moisture in order to obtain the most desirable
15 results.
In conditioning tobacco prior to the bleaching
step, not only is it desirable to include in the
tobacco a substantial amount of moisture but
also further advantages are obtained by seeing
20 to it that the moisture is distributed as uni
formly as possible in the tobacco. Ordinarily
tobacco contains some moisture, but the moisture
is not sufficient in amount or distributed evenly
enough to obtain the most desirable bleaching
25 effects. The most desirable bleaching effects
are produced when the tobacco carries a rela
tively large amount of moisture which is sub
stantially uniformly distributed in all parts of
the tobacco. Thus,‘ in the normal practice of this
30 invention, the conditioning of tobacco prior to
bleaching preferably includes a moistening step
as by immersion inwater or contact with a humid
After the tobacco has been treated as above
described, it can be dried so-that it will have
the moisture content that is desired in the fin
ished product. The product not only is im
proved in color, namely, is bleached to a pleasing
light brown color, but also retains its ?avor and
aroma substantially unimpaired. In certain
cases, the treatment above described has been
found to result in de?nite improvement in the
texture of tobacco which originally was of a 10
coarse character and in improvement in the
flavor. In preferred practice of this invention,
the tobacco is treated further to incorporate salts
therewith which improve the burning properties
of the‘tobacco. Thus not only will the tobacco
be improved in color, but also will have its burn
ing properties improved.
In the practice of this invention, the steps
thereof, materials used and items of apparatus
included therein may be employed conjointly and 20
when so used one obtains the special advantages
of such conjoint use but it is to be understood
that such features of this invention may like
wise be employed separately in achieving some
of the advantages of this invention.
25
Oxide of nitrogen for use as a bleaching agent
in the practice of this invention may be pre~
pared in several known ways. Preferably, the
means used for generating oxide of nitrogen is
such as to result in the production of a major 30
proportion of nitrogen tri-oxide. For‘ purposes
of illustration, certain desirable methods for sup
atmosphere and. in addition a further step, by' plying oxide of nitrogen will be described.
(a) Oxide of nitrogen may be generated by
which the moisture is evenly distributed in the
tobacco. In certain instances, these steps-may catalytic oxidation of ammonia. This may be 35
be combined, but preferably they follow each accomplished by passing oxygen or an oxygen
other. Especially when the tobacco is in leaf containing gas in admixture with ammonia over
form, the conditioning treatment may include a a catalyst such as heated platinum gauze. A
drying operation in which any excess moisture, suitable mixture of NO and N02 which results
in the formation of N203, can be obtained by
40 occurring, for example, as droplets of free mois
ture, is removed by such. methods as contacting judicious choice of temperature and oxygen feed
the tobacco with absorbent rollers and/or expos- '
as is well known. The gas can be taken directly
ing the tobacco to an atmosphere, having such
from the generator to the chamber in which to—,
humidity as to leave a desired amount of moisture
45 in the tobacco without excess on the surface.
bacco is being treated or it can be lique?ed and
stored for subsequent use in any concentration
which is desired.
(b) Oxide of nitrogen can also be generated
In the bleaching step the tobacco, preferably
after it has been placed in a receptive condition
for bleaching as above described, is exposed to
oxide of nitrogen and this is preferably accom
plished bydisposing the tobacco in such a way
50
that the surfaces thereof will be in contact with
an atmosphere containing oxide of nitrogen.
Preferably, the tobacco is exposed for a relative
ly short time to an atmosphere containing a rel
atively high concentration of oxide of nitrogen
at moderate'temperatures and for best results
both the tobacco and the atmosphere in which
the tobacco is placed contain a relatively high
amount of moisture.
Further details of bleach
60 ing treatment and the conditions under which
the bleaching is effected will be described below.
After the bleaching step, the tobacco is sub
jected to further treatment to place it in better
form for marketing. After the bleaching step, it
65 is usually desirable to subject the tobacco to
washing with water or air or both water and air
to remove from the tobacco oxide of nitrogen
by decomposing nitrates such as copper nitrate,
lead nitrate, barium nitrate, etc. The decomposi
tion of such nitrates with the generation of ni—
trogen oxides may be accomplished by means of
heat.
(0) Oxide of nitrogen can also be prepared by
the reaction between metals such as copper, tin,
silver, etc., and nitric acid to produce oxides of
nitrogen, including nitrogen tri-oxide.
Further purposes, features and advantages of
this invention will be apparent in connection
with the following description'of specific illus
trationsvof the practice of this invention in com
nection with the accompanying drawings, where
in:
Figure 1 is a flow sheet wherein the steps com
prising one method of bleaching and treating
tobacco according to this invention are indicated;
Figure 2 shows diagrammatically a side sec
tional view of one form of apparatus for treat
and/or acid carried thereby. The washing step
is then preferably followed by a neutralization.
70 step which neutralizes any acidic matter remain
ing in the tobacco after the washing operation.
While it is preferable to first Wash the bleached
tobacco and then neutralize the tobacco, it is
paratus shown in Figure 2;
possible to combine those steps by washing the
75 tobacco with a mildly alkaline solution.
to this invention;
ing tobacco according to this invention‘;
Figure 2-A shows a continuation of the ap
70
Figure 3 shows diagrammatically a side sec
tional view of an alternate form of apparatus
which may be used in treating tobacco according
Figure 4 shows diagrammatically a side sec
75
3
2,181,160
tional view of apparatus for use in neutralizing
or chemicalizing the'tobacco and
Figure 5 is a plan view of a portion of the screen
conveyor employed in connection with the appa
ratus shown in Figures 2 and 2-A.
>
proximately saturated with moisture. Care
should be taken, however, ‘not to introduce such
an excessive amount of moisture that free mois
ture will condense on the tobacco. The tobacco
is maintained in the chamber 26 until the mois
ture content of the tobacco is substantially uni
An illustration of the practice of this invention
will be given ?rst in connection with the appara - form throughout._ To afford a speci?c.illustra
tus shown in Figs. 1, 2,-2-A and. 5. The tobacco tion, the tobacco is maintained in chamber 26
to be treated is normally cured tobacco in the until it is about 85% to 95% saturated with mois
form of partially dried leaves. Such tobacco, for ture throughout. - The presence of free drops of 10
example, is preferably ?rst introduced into wet
water on the surface of the tobacco is preferably
ting or moistening chamber l0. In the chamber
lo, the tobacco is subjected to water either in liq
.15
avoided. .
>
Alternatively in the chamber 26, the atmosphere
uid or vapor state to preliminarily wet the tobacco ' may be kept in a humidi?ed state by other suit‘
so that the tobacco will be'more receptive to the able means such as inlets 6| for steam or water 15
subsequent bleaching operation and so that the which can be distributed in the chamber to main
leaves will be rendered‘pliable and free from each tain the desired humidity therein.
other. The chamber I0 is provided with suitable
When the leaves emerge from-the chamber 26,
inlets for water and/or‘steam.
Thus the cham- _ they are treated to remove free moisture, thereon,
20 ber may be provided with one or more water inlets,
such as inlet || controlledby valve I3 and leading
to spray nozzle M which is adapted to spray water
-upon the tobacco leaves I 5 hanging on racks I6.
Steam may also be introduced ‘into, the chamber
25 bymeans of steam lines I‘! controlled by valves'
l8. To maintain'the conditions in chamber H)
if any, as by passing the leaves between rollers '20
30. The rollers are preferably made of some
water-absorbent material, such as cloth. If the
conditioning inchamber 26 is carefully conducted,
the rollers 30 may be dispensed with as exposure to
atmosphere in chamber 26 can be controlled so as 25
to prevent the existence. of free water on the to
as uniform as possible, one or more agitators I9 ‘ bacco. However, especially when there is an ex
driven by any suitable means, not shown, may be cess of moisture in chamber 26, the employment
employed. - The chamber l0 may have a suitable
30 drain 20 to take o?‘ excess water or steam con
>
densate.
<
After the tobacco has been moistened in cham
ber IE, it is preferable to further condition the
tobacco before it is subjected to .the bleaching
35 treatment which‘ is to follow.- For this purpose,
of special means such as rollers 30 to remove free
water is desirable.
-
30
The tobacco leaves by the foregoing arrange
ment are placed‘ in a condition to be bleached
in bleaching chamber 3|, which, together with
the other apparatus associated with this cham
the tobacco leaves are loaded in ?atwise arrange
ber-fare preferably made of some non-corrosive 35
material, such as stainless steel. Alternatively
ment on one or more continuous conveyors pref
‘wood or concrete lined with asphalt or other
erably in the form of a'coarse screen which is
resistant material may be used. In this chamber,
- made of a suitable non-corrosive material, such , the tobacco is exposed to an atmosphere compris
as stainless steel and which offers as small an , ing oxide of ntirogen which is introduced into -
area of contactas possible with the tobacco.
leaves. In Figs.- 2 and 2-A two conveyor screens
2|, of this type are shown. Detail of such screens.
I is shown in'Fig. 5, reticulated wires “being em
ployed. The loading of the tobacco on the ‘screens
, is accomplished in the loading room 22.
In order
chamber 3| by line 32 controlled by valve 33.
Adjacent openings 34 through which the con
veyor screens 2| and 23 pass are ?ap valve ar
rangements 35 which may be made of ?exible
material such as rubber so as to ‘prevent at least.
to'insure against displacement of the tobacco
in part the escape of oxide of nitrogen from the
chamber 3|. If there is excess of oxide of nitro
. leaves, screens 23 which may be similar to screens
gen in chamber 3| , such excess can be withdrawn
45 '
2| are employed and are adapted to become through take-off line 36 controlled by valve 31.
50 superimposed upon the tobacco resting upon‘ In order to keep the atmosphere in the chamber3| 60
screens 2| during’ the travel ~' of .the tobacco homogeneous, agitators 38 are employed which
through the apparatus.‘ vTeH afford. continuous
may be driven by any suitable‘wmeansl ‘(not
movement of the screens 2| and 23, rollers 24 and - shown). ' Likewise, distributing nozzle 39 is pref
- 25 are employed.
Any one or more of such roll
55 ers may be driven by suitable meansnot'sho'wn.‘
The movement of the‘ screens in carrying the
tobacco through the apparatus may be continuous
or intermittent as‘ desired.
, ‘ After the tobacco has been loaded upon the
60 conveyor screens, it is introduced into condition
ing chamber 26 in vwhich the tobacco attainsthe
erablyemployed. The chamber3| may be provided
with a drain 40 and- to control the temperature in
the chamber a coil 63‘ or other similar device is
preferably employed, through which heating or
cooling fluid may be circulated. ,
By way of illustration, the previously condi
tioned tobacco is exposed in chamber 3| to an 80
atmosphere containing about 15 to 35% of, oxide
' desired-amount of moisture, substantially uni- I‘ of nitrogen ,of which the major portion is nitro
‘ formly distributed in the tobacco.
gen tri-oxide. The balance of the atmosphere in
atmosphere in chamber 26 can be main ‘ the chamber may be air. The atmosphere in the
at desired humidity by any suitable means. chamber is preferably'of,high’humidity, i. e. just 65
drawings, an air inlet 21, is shown through below 100% saturation. For this purpose, steam
air previously conditioned to the proper may be mixed with the oxide of nitrogen that is
' degree of humidity is'introduced, , The air thus introduced into the chamber as by steam inlets
introduced escapesthrough the various openings 66 controlled by valves 61. The chamber is pref7
28 through which the conveyor screens 2| and 23 erably maintained at a temperature of about 20° 70
pass. ' To keep the atmosphere in the chamber'26 C. Under those conditions the‘ tobacco is
as uniform as possible, agitators 29 driven by ‘any bleached to a pleasing light brown color in about
The
tained
In the
which
suitable means (not shown) are preferably em
ployed. The air that is introduced through inlet
~75
_ 15 to 30~minutes.
In order that the concentration of oxide of ni
21 is preferably and by way of illustration ap- . trogen may be kept constant in the chamber 3|, 75
2,181,160
some means for rapid analysis is required. For
this purpose, I utilize the optical characteristics
of the gaseous mixture in the chamber and have
associated with the chamber 3| 9. device indi
catedv generally by the reference character 62.
The device may comprise known means respon
sive to the optical characteristics of the atmos
phere such as the index of refraction of the at
mosphere or the light absorption characteristics
10 of the atmosphere. By having the device proper
ly calibrated ‘the concentration of the oxide of
nitrogen in the chamber 3! may be readily deter
. mined at any time.
At the completion of the bleaching treatment,
15 the tobacco is passed into a washing chamber 4|,
where the tobacco is either immersed or sprayed
with water. Preferably sprays such as sprays 42
are employed, which spray water over the leaves
on the conveyor screens passing through cham
20 ber 4|. The washing may include subjecting the
leaves to blasts of air which aids in degassing the
tobacco. By incorporating an alkaline material
such as ammonia with the air, the atmosphere
thus can be employed to neutralize any acid car
.25 ried by the tobacco. As the leaves pass into
and/or out of the chamber, they may be subject
ed to direct rinsing action either with water or
moisture conditioned air directed against the to
bacco by nozzles 43. The chamber 4| is provided
,
30 with an outlet 66.
The tobacco may likewise be subjected to an
ous conveyor screen of the type shown in Figs. 2
and 2-A, the tobacco may be heated while
disposed on other types of carriers. Thus, car
riers 53 of any suitable type may be employed. In
the embodiment shown in the drawings, the car- _
riers 53 comprise a plurality of racks or frames
54 from which the tobacco is suspended in
“hands” or as free leaves with the leaves as tree
from each other as possible. The tobacco can be
placed on the carriers 53 after having been 10'
moistened in a chamber such as the chamber In
shown in Fig. 2. The carriers 53 are mounted
on wheels 55 adapted to travel on floor 56.
In Fig. 3, a treating chamber 51 is shown
through which the carriers 53 can pass. Pref 15
erably, the treating chamber 51 is provided with
outer doors 58 and inner doors 5!! which doors
are spaced from each other in the direction of
travel of the conveyors 53 therethrough. With
this arrangement, one of the doors 56 'may be
opened, for example, while the door 59 adjacent
thereto is closed, so that a carrier 53 may be
placed in the space between these doors. There
after, the door 58 is closed and the door 59 opened
so that the carriage 53 may be moved into the 25
inner part of the treating chamber. The car
riage 53, after the tobacco has been treated in
the treating chamber may be removed from the
chamber by ?rst opening a door 59 to bring the
carriage between door 59 and door 58, then clos 30
ing the door 59 and lastly opening door 56. Any
other type of neutralization treatment. For this
number of carriages such as carriages 53 may
purpose, the conveyor screens are passed through
a neutralization tank 44 containing an alkaline
35 liquid 45, such as a solution of sodium or potas
sium carbonate or bicarbonate or other alkaline
be included in the chamber‘51 between doors 59
reagent. The conveyor screens are guided
through the alkaline solution by means of a plu
and in normal operation as one carriage 53 is
moved into chamber 51 another carriage bearing 35
bleached tobacco is moved out of the chamber in
the manner above described.
The treating chamber 51 may be substituted
for any of the treating chambers i0, 26, 3|, 4!
rality of guide rollers 46 and 41. A mildly alkaline
solution having a pH value of about 8 is preferred.
In the neutralization step, any remaining nitric
or 49 shown in Figs. 2 and 2-A. The treating 40
chamber 51 of the type shown in Fig. 3 is espe
acid is converted into neutral nitrates which are
cially adapted, however, for subjecting tobacco
to the bleaching action of oxides of nitrogen.
useful in improving the burning properties of the
tobacco. To place the tobacco in condition for
45 marketing,it is carried by the conveyor screens be
tween rollers 48 in the event that a neutralizing
solution has been employed which remove some of
the excess moisture and then into drying chamber
49. In the drying chamber, the leaves are sub
jected to an atmosphere of desired humidity.
Conditioned air is introduced by means 01' inlet
50 and withdrawn by outlet 5!. ‘The atmosphere
in chamber 49 is preferably agitated by means
of agitators 52 which are driven by any suit
55 able means (not shown). In the chamber 49,
the leaves attain the moisture content which is
desired, depending upon the purpose for which
the tobacco is intended. As the tobacco emerges
from the chamber 49, it is-unloaded from the con
veyor screens and is in condition for any com
mercial use that is desired.
As shown in the ?ow sheet of Fig. 1, the water
from chamber 4| which is somewhat acidic in
character'may be neutralized for the recovery of
65 salts. This may be done by evaporating the salt
solution by any suitable means. At the same
time that this solution is evaporated for the re
covery of salt, waste solution from the neutral
izing tank may likewise be evaporated in the
evaporator for the recovery of the salt content
thereof.
To further illustrate the practiceof this inven
tion and possible embodiments thereof, it will be
described in connection with ‘the apparatus shown
in Figs. 3 and 4. Instead oi employing a continu
When used for this purpose, the chamber may
be supplied with suitable inlets, outlets and 881 45
tators of the type shown in Figs. 2 and 2-A. By
such construction, the interior of the chamber
can be maintained with a desired concentration
of oxides of nitrogen therein and the carriers 53
may be moved therethrough so as to subject to
50
bacco thereon for the desired length of time to
the action of oxides of nitrogen.
A chamber such as the chamber 51 may also
be employed to preliminarily condition the to
bacco in the same way that chamber 26 is em
55
ployed. For example, conditioned air may be
passed into and out oi’ the chamber by means
of any suitable arrangement of inlets and out
lets. A chamber such as chamber 51 may also be
employed to wash the tobacco after it has been
bleached and for this purpose one or more sprays,
such as the sprays 42 shown in Fig. 2-A may be
employed.
when it is desired to subject the tobacco on
carriers 53 to a neutralizing bath, this can be
done in several ways. According to one method,
the entire carrier 53 can be bodily removed from
the floor 56 and immersed in an alkaline solu—
tion 60 in tank 65. After the neutralization
treatment, the carrier may be removed from the 70
tank 65 and taken to any suitable drying cham
ber in which the air is preferably conditioned
so that the desired amount of moisture will be
retained in the tobacco.
While movement of tobacco between successive
2,131,160
chambers has been described above in practicing
the process of this invention, it is apparent that
any number of steps and even the entire process
may be carried out in a single chamber. Thus
the tobacco could be placed in a single chamber
such as chamber 51 and moistened by sprays.
The tobacco could then be exposed to conditioned
air, bleached, washed, neutralized and dried while
remaining in the chamber ‘by varying the condi=
10 tions in the chamber. It could also be treated to
improve its burning qualities. After completion
of the treatment of one batch, a second batch
could be similarly processed.
>
5
ciples underlying this invention will be discussed
from a-more general point of view. Thus, the
preliminary wetting and/or conditioning can be
varied considerably and can even be eliminated
especially when the tobacco is received in a rela
tively moist condition. Howeven if the prelimi
nary wetting and conditioning'are eliminated,
tests have shown that inferior bleaching is nor
mally effected in the case of tobacco in the con
dition in which it is ordinarily received. About 10’
10% to 30% of moisture is desirable in the to
bacco prior to bleaching. When the tobacco con
tains about 30% of moisture, it approaches sat
The foregoing description has been con?ned
15 principally to method and apparatus for the
bleaching of tobacco to improve its color. It is
of great signi?cance and importance that the
bleaching to desired light color is accomplished
without substantial impairment of the flavor and
less than 10% of moisture, more time is required
for bleaching and it is difficult to obtain uniform
20 aroma of the tobacco.
bleaching. If the tobacco is too dry during the 20
In addition to the fore
going, the tobacco can be further improved ‘in
the practice of this invention so that it will have
better burning properties. For this purpose, the
tobacco is treated with one or more salts of
25 nitric acid or of mono- or poly-basic organic acids
having 1 to 5 carbon atoms, the salts being .salts
of metals selected from the group consisting of
alkaline earth metals, alkali metals and mag
nesium. Preferably, alkali metal salts of such"
30 acids are used in conjunction with alkaline earth
salts and/or magnesium salts of suchacids. For
example, the tobacco may be treated with po
' tassium nitrate in admixture with magnesium or
calcium nitrate as a combination of prepared
35 salts. Other alkali metal salts of such acids mayv
be used such as the sodium salts. Of the alkaline
earth salts, the salts of » calcium and strontium
are preferred.‘ Illustrations of mono- and poly
basic organic acids having 1 to 5 carbon atoms
40 are citric acid, acetic acid and oxalic acid.
The treatment of tobacco with the salts above
uration. If about 15% to 25% moisture is con
tained in the tobacco, the best results are 15
achieved. However, nearly complete saturation
gives excellent results.
If the tobacco contains -
entire exposure to oxide of nitrogen, very inferior
bleaching or no bleaching is obtained.
In preliminary conditioning the tobacco, the
vwetting and moisture conditioning steps may be
combined, but if wetting alone is employed, care 25
should be taken to remove ‘free ,water from the
surface of the tobacco by exposure to air of uni
form humidity or by mechanical means. Pro
‘ longed soaking is not'ordinarily desirable, how
ever, as ‘this is likely to result in some loss of 30
aroma. Conditioning in a humid atmosphere has
been found to best preserve the ?avor and aroma
of the tobacco.
-
-
In the bleaching operation the concentration .
of oxide of nitrogen in the bleaching chamber 35
may vary from about 5% to 50%. Concentrations
even as high as 100% may be employed,‘ but to
operate with such high concentration requires ex
cessive generation of the oxide of nitrogen and at
tendant increased expense. Also, it has been 40
1 found that the lower concentrations above men- '
mentioned may be accomplished in any suitable ~ tioned aiford'a more desirable product. Likewise
concentrations of oxide of nitrogen as low as
Way so ‘that the salts will be incorporated there
with. ,The term incorporated therewith includes
45 impregnation of the tobacco or surface applica
tion of the tobacco with- the salts. The salts
may be incorporated with the tobacco, for ex
ample, ‘by placing a‘. solution of such salts in the
tank 44 in lieu of a‘neutralizing solution. Pref
50 erably, however, the tobacco is. ?rst subjected to
neutralization in tank 41 and is ‘thereafter treat
ed with the salt solution.
For this purpose, a
second tank similar to tank “may be employed in
which the tobacco is immersed in the salt solu
55 tion.
Alternatively, the tobacco while on a car
rier of the type of carrier 53 may be immersed
in a solution of such salts.
The concentration
of the salt solution is'preferably from about 3%
to S%% although solutions containing approxi
mately 1% to 5% may also be advantageously
employed. It is understood, however, _that the
concentration may be varied without departing
, from the scope of this feature of my invention.
Immersion of the tobacco leaves for about 2 to
65 30 minutes in the usual case is su?icient to per
mit absorption of salts and about 5' to 10 min
utes is ordinarily enough. After the chemicall
zation of the tobacco has been completed the to
bacco can be dried as above described.
70 While certain examples of the practice of this
invention have been given above, it is apparent
that the procedure above described can be varied
considerably without departing fromthe scope of
this invention. For purpose of affording a fuller
75 understanding of this invention, some of the prin
1% may a?'ord some bleaching under favorable
conditions of temperature and moisture but the 45
time for achieving substantial bleaching at such
low concentrations .is impractical commercially.
Preferably about 10% to 40% of oxide of nitrogen
is employed. v As the concentration of oxide of
nitrogen is increased, the bleaching action is more 50
rapid.
When a concentration of ,the oxide of
nitrogen is about 15% ,to 25% bleaching can be
accomplished in about 15 to 30 minutes to produce
a pleasing color. If the concentration of the oxide
of nitrogen is about 5%, the bleaching is some 55,
what slower and can be accomplished in about
30 minutes to 1 hour depending upon the amount
of bleaching/desired. Preferably, an atmosphere
containing about 10% to 40% of oxide of nitro
gen. is employed for periods of from about ?ve 60
minutes to one hour.
'
'
The temperature at which the bleaching is con
ducted may vary f-rom about 10° C.‘ to about
50° C. although temperatures of from about
18° C. to 35° -C. are normally to be pre
ferred. As the temperature is lowered, the bleach
ing action is slower and there is likelihood of
condensation of water and/or oxide of nitrogen.
‘At higher temperature than about 50° C. the re
sulting bleached tobacco does not have as desir- '
able a texture. If excessively high temperatures
are used together with high concentrations of
oxide of. nitrogen and long periods of time the
tobacco may be rendered somewhat brittle and
there may be some impairment of the ?avor of 75
6
2,131,100
the tobacco. But such extreme conditions are
not necessary as even extremely pale effects can
be secured according to this invention without
substantial weakening of the texture of the to
bacco or impairment of ?avor.
The atmosphere in the bleaching chamber pref
erably carries a high degree of humidity. If
tobacco, which is nearly saturated with moisture
is carried into the bleaching chamber, the at
10 mosphere tends to become moist. However, it is
normally preferable to introduce moisture along
with the oxide of nitrogen into the bleaching
chamber so that the atmosphere is more than
about 75% saturated with moisture. Preferably,
15 the atmosphere in the bleaching chamber is about
85% to 95% saturated. It is preferable to avoid
complete saturation as this tends to cause forma
tion of droplets of free moisture on the tobacco
with resultant non-uniformity of bleaching.
The washing step, after the tobacco has been
bleached, may be modi?ed so that the tobacco is
either de-gassed with conditioned air or by means
of water. These steps may even be eliminated
so that the washing is conducted in an alkaline
solution, the washing and neutralization thereby
has improved texture. As a result of the treat
ment, small quantities of reaction products re
sulting from the reaction between ingredients in
tobacco and oxide of nitrogen are retained in the
10
tobacco.
When the tobacco is neutralized with an alkali
metal compound, the small amount of acidity
that is neutralized is chie?y due to nitric acid
that is formed as a result of the action of oxide
of nitrogen and moisture in the tobacco and in 15
the bleaching chamber, and the neutralization
process leaves a small amount of alkali metal
nitrate in the tobacco such as sodium nitrate or
potassium nitrate. When alkaline compound of
alkali metals are used for neutralization, the
presence of such nitrates, together with com
pounds that are reaction products between con
stituents of the tobacco and nitrogen oxides fur
ther identi?es one type of tobacco treated ac
cording to this invention and likewise serves to
improve the burning properties of the tobacco.
The incorporation with tobacco of salts of alkali
tobacco in a liquid or alternatively by means of
sprays. Or the use of liquid neutralizing agents
salts are formed from nitric acid and/or organic
above, an atmosphere containing gaseous am
monia, or ammonia itself in the pure state, may
be used to accomplish the neutralization. Like
wise, the neutralization chemicals may be com
bined with the salts above described which are
utilized to improve the burning properties of the
tobacco.
'
It has previously been mentioned that it is
40 preferable to treat tobacco according to this
invention after it. has previously been cured.
By previous curing it is meant that the curing
has progressed until the tobacco has become dark
ened to such an extent that the bleaching proc
es of this invention may be utilized in improving
the color of the tobacco. In ordinary practice,
the tobacco is ?rst cured and thereafter the dark
tobacco is treated according to this invention to
improve its color and/or burning properties and
50 this is the preferred practice. subjecting any
tobacco to treatment of the nature above de
scribed to accomplish substantial bleaching in a
tobacco product is, however, to be regarded as
coming within the scope of this invention.
While the bleaching has been described in con
nection with exposing tobacco to an atmosphere
containing oxide of nitrogen in gaseous form, it is
not without the scope of this invention to ex
pose tobacco to oxide of nitrogen in other ways.
60 For example, oxide of nitrogen may be dispersed
in water or other vehicle which is contacted with
the tobacco so that the tobacco is subjected to
the bleaching action of the oxide of nitrogen.
While speci?c forms of apparatus have been
described it-is to be understood that this has
‘been done for purposes of illustration and that
the speci?c forms shown are subject to consider
able variation.
70
greatly improved color. Likewise, it frequently
being performed in a single operation. The neu
tralization may be performed by immersing the
and washing may be entirely omitted and only
gaseous neutralization employed. As described
55
pers thereof and make them 0! more pleasing
appearance.
The tobacco that is produced in the practice
of this invention has increased value due to its
'
The foregoing description has been directed
chie?y to the treatment of leaf tobacco. How
ever, ?nely divided tobacco can also be treated
according to the invention and appropriate car
riers therefor used. Likewise, ?nished articles
76 such as cigars can be treated to bleach the wrap
metals, alkaline earths, and magnesium, which
mono- and poly-basic acids having 1 to 5 carbon .
atoms has been discussed above andthe presence
of such added salts further distinguishes pre
ferred embodiments of this invention.
'
While this invention has been described above
in connection with a number of speci?c examples
of embodiments thereof, it is to be understood
that this has been done merely for the purpose of
illustration.
'
I claim:
1. A method of treating cured tobacco which 40
comprises effecting substantial bleaching of to
bacco by exposure of cured tobacco in the pres
ence of a substantial quantity of moisture to
oxide of nitrogen, said oxide of nitrogen being the
primary bleaching agent.
2. A method of treating cured tobacco which
comprises effecting substantial bleaching of
cured tobacco by exposure of said cured tobacco
to moistened oxide of nitrogen, said oxide of ni
trogen being the primary bleaching agent.
3. A method of treating cured tobacco of dark
color which comprises exposing the cured to
50
bacco in a moistened condition to an atmosphere
containing oxide of nitrogen to afford substantial
bleaching of the tobacco.
55
4. A method of bleaching tobacco which has
previously been cured which comprises exposing
the cured tobacco containing over about 10% of
moisture to an atmosphere containing over 5%
of oxide of nitrogen, initially in gaseous form to 60
afford substantial bleaching of the tobacco.
5. A method of treating cured tobacco which
comprises wetting thetobacco, moisture condi
tioning the tobacco by exposure to atmosphere to
effect substantially even distribution of moisture
in the tobacco, and bleaching the tobacco in a
uniformly moistened condition by exposure to
oxide of nitrogen, initially in gaseous form.
6. A method of treating cured tobacco which
comprises molstening the cured tobacco, subject
ing the moistened tobacco to an atmosphere of
oxide of nitrogen initially in gaseous form, re
moving the tobacco from said atmosphere con
taining oxide of nitrogen, and washing the to
bacco.
2,181,160
'7. A method of treating cured tobacco which
comprises moistening the cured tobacco by condi
tioning by exposure to humidi?ed air, subjecting
the moistened tobacco to an atmosphere of
14. A method of treating cured leaf tobacco
which comprises washing the leaves to moisten
them, moisture conditioning the leaves by ex
posure to atmosphere so that the leaves will con
tain about 15% to 25% of moisture, removing any
free drops of water on the surface of the leaves,
vexposing the tobacco leaves to an atmosphere
containing about 10% to 40% of oxide of nitrogen
co with moisture conditioned air.
.
8. A method of treating cured tobacco which a major proportion of which is in'the form of
N20: which atmosphere is about 85% to 95% 10
10 comprises moistening the cured tobacco, subject
saturated with moisture at a temperature of from
ing the moistened tobacco primarily to an atmos
phere of oxide of nitrogen applied initially in about 18° C. to 35° C. to bleach the tobacco, and
gaseous form, removing the tobacco from said washingv and neutralizing the bleached tobacco.
15. A tobacco leaf wrapper having cured and
atmosphere containing oxide of nitrogen, and
bleached characteristics, the bleached character 15
15 neutralizing acid carried by the tobacco after the istics being obtained by exposure of previously
bleaching step.
9. A method of treating cured tobacco which cured tobacco primarily to oxide of nitrogen, in a
omde of nitrogen initially in gaseous form, re
moving the tobacco from said atmosphere con
taining oxide of nitrogen, and washing the tobac
comprises moistening the cured tobacco, subject
ing the moistened tobacco to an atmosphere of
20 oxide of nitrogen applied initially in gaseous form,
removing the tobacco from said atmosphere con
taining oxide of nitrogen, and neutralizing the
tobacco after bleaching with an alkaline solution.
10. A method of treating cured tobacco which
comprises moistening the cured tobacco, subject
ing the moistened tobacco to an atmosphere of
oxide of nitrogen applied initially in gaesous form,
removing the tobacco from said atmosphere con
taining oxide of nitrogen, and neutralizing the
30 tobacco after the bleaching step by contacting the
tobacco with an atmosphere containing ammonia.
11. A method of treating cured leaf tobacco
which comprises moistening the tobacco leaves,
distributing the moisture substantially uniformly
35 in the tobacco leaves without free moisture on the
moistened condition. ,
16. A tobacco article consisting of cured tobac
co having a bleached characteristic, said char
20
acteristic being obtained by treating the tobacco
primarily with oxide of nitrogen in the presence
of a substantial amount of moisture after the to
bacco has been cured, and having added to it an
alkali metal nitrate.
,
'
>
25
17. A tobacco leaf wrapper havin'g cured and
bleached characteristics, the bleached character
istics being obtained by exposure in a moistened
condition primarily to oxide of nitrogen and hav
ing incorporated therewith an added salt of a 30
metal selected from the group consisting of alkali
metals, alkaline earth metals, and magnesium
formed with an acid selected from the group con
sisting of nitric acid and organic mono- and poly
basic acids having 1 to 5 carbon atoms.
18. A tobacco article consisting of cured tobac
co having a' bleached characteristic, said char
acteristic being obtained by treating the tobacco
primarily with oxide of nitrogen after the tobacco
has been cured, and having incorporated there
with added salts comprising a ?rst salt selected
tacting it with an atmosphere containing am- ' from the group consisting of alkali metal salts of
nitric acid and of organic mono- and poly-basic
monia and air-conditioning said tobacco.
acids having 1 to 5 carbon atoms, and a second
12. A method of treating tobacco which com
salt selected from the group consisting of alkaline
prises
subjecting
the
tobacco
to
an
atmosphere
45
containing a concentration of 5% to 50% of earth metal salts and magnesium salts ‘of nitric
acid and of organic mono- and poly-basic acids
N203.
.
13. A method of treating cured tobacco which having 1 to 5 carbon atoms.
19. A method of treating cured tobacco which
comprises moistening tobacco substantially uni
comprises effecting substantial bleaching of to
50 formly throughout, exposing the .tobacco to an bacco by exposure of cured tobacco in an atmos
atmosphere containing about 5% to 50% of oxide
of nitrogen at a temperature of from about 10° C. phere containing a substantial proportion‘ of
to about 50° 0., removing the tobacco from said moisture to oxide of nitrogen, said oxide of nitro
gen being applied originally in gaseous form.
atmosphere, and then neutralizing any acid car
‘
SOUREN Z. AVEDIKIAN.
65
55 ried by the tobacco.
surface thereof, subjecting the tobacco to an at
mosphere containing more than 5% of oxide of
nitrogen initially in gaseous form at a temper
ature between about 10° C. and about 50° C. to
40 bleach the tobacco, removing the tobacco from
said atmosphere, neutralizing the tobacco by con
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