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Dec. 10, 1946.'
ç;v BRUNKHURST
2,412,203
PRESERVATION OF MILK PRODUCTS
Filed April 27. 1945
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2,412,203
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UNITED STATES PATENT IOFFICE
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2,412,203"
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«gansaavs'noiv or MILK raonuc'rs Y
charles'ßmnknmt, Mid'dietnwn, N. Y.
Application April 27, 1943, Serial No. 484,716
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nection with the accompanying drawing forming
-a part- thereof, in which
-Fig. 1 illustrates diagrammatically one form
of apparatus for the quick freezing step, using
rotating drums;
h
Fig. 2 illustrates diagrammatically another
form of apparatus for quick freezing the con
centrated milk and cream in batches;l
milk powder. Such reconstituted whole milk is
generally unsatisfactory. _’ Either the vreconsti
tuted milk has a poor appearancev or it lacks
flavor, generally both: ' Attempts have been/made 10
to improve the quality of the reconstituted whole
milk either by freezing fresh whole milk in its
2
ring to the following description taken in con
The invention relates to the preservation of
milk products and more particularly to obtain
ing a satisfactory reconstituted whole milk. /
.
At the `present time, the common practices forobtaining a reconstituted whole milk are to add 5
water to preserved evaporated whole milk or to
Fig. ' 3 -illustrates diagrammatically another
form of apparatus for .quick freezing the con
centrated milk and cream ina continuous proc'
ess; and
original state or by freezing evaporated milk.
Fig. mnustrates dmgramiñaticany a not wa
Freezing of the fresh whole milk,y in its original
state is, of course, open to the additional objec- 15 ’ter-air blow type of concentrator suitable for
tion of having too much- bulk for storagepur- ~
practicing the invention.
poses. In all .cases the Whole >milk available
for drinking is defeçtive in both appearance and
In the following description and in the claims,
various details will be identified by specific names f
,
taste. Either the fats and solids separate\out,
for convenience, but they are intendedy to be as
or the'milk has a brownish ,color, or it has a flat, 20 generic inftheir application as the art will permit.
tinny, caramel, burnt or other'unpleasant taste.
In the ’drawing accompanying and forming
An important feature of the present invention ~ part of this specification, certain specific dis- .
-is the manufacture of a frozen concentrated i
closure ofthe invention is made‘for purposes ’ '
whole milkl product which, when water is added. «
of explanation, but it willbe understood that the Y
will be so like the originel fresh Whole milk in 25 details may bemodined in various respect without r
consistency, appearance and taste thatl it would
departure from the broad aspect of the inven
be difficult, if not impossible, for anyone to tell ,i
the difference.
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tion.
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Referring now to the drawing, the apparatus
According to a preferred embodiment of the
for carrying out the quick freezing step will first
invention, the whole unpasteurized milk, as it is 30 be described. In Fig. 1 a pair of rotating hori
qbtained from the farmer, is subjected to a cream
zontal hollow cylinders Ill and i-l are rotatably
separating process for separating the cream from
- mounted, these cylinders having smooth -surfaces
the skim milk. The skim milk is then suitably
and being in direct contact. They are suitably
concentrated in a hot water-air blow type congeared together and rotated in the direction of
centrator to reduce the` water content'. ,The 35 the“ arrows. The apparatus illustrated-in Fig. 1
cream is separately pasteurized, after which the -
is similar in principle to machines now on the `
a concentrated skim milk and cream is re-mixed.
market, known as ‘"Flake-Ice” or"‘Pak-Ice,” used
The mixture is then homogenized, while/hot, to
for making artificial ice. Scrapers i3 and i4
, break up the fats and solids, to insure .thorough
,
'engage the drums to scrape off the mix freezing
. emulsiilcation. The mixture is then subjected in 40 on the drums, the mix being fed through pipe I2
diffused form to quick freezing to freeze the mix
as indicated.
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ture whence it may be formed into frozen cakes
‘ Referring now to Fig. 2, a batch-type quick
for shipment to the trade in the same manner >/i’reezing apparatus is diagrammatically illus
as any frozen food product. The cakes may be
trated. This device comprises a cylinder 2li hav
formed in suitable size to which the consumer 45mg a suitable cooling jacket 2|. Rotatably
adds water to form the reconstituted whole milk.
mounted within the cylinder is a shaft 22 carry
The invention also consists in certain new and
ing a drive pulley I9 and helical blades 23 simi
lar in shape to lawn mower blades and closely ñt
original features and' combinations `hereinafter
set forth and claimed.
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Although the novel features which are believed
to be characteristic of this invention will be par
ticularly pointed out in the claims 'appended here
to, the invention itself, as to. its objects and ad
vantages,- andthe manner'in which it may be
carried out, may be better understood by refer-
ting the walls of the cylinder. A removable _head
24 is suitably clamped on Ato the cylinder, this
cylinder carrying a feed hopper 25 having feed
valve I8 and a discharge pipe v28 havingga dis
charge valve 21. A receptacle 28 is illustrated for
receiving the frozen min. vA _refrigerating me
dium, 'such as refrigerated-brine or ammonia, is
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, 9,419,908
about 170° F. so that the milk contacting the
circulated through the jacket 2I inthe direction
of the arrowsthrough pipes 29 and 30, as will be . walls of the jacket and the hot water coil 51 w`
not become scorched or cooked. At the same time
understood by those skilled in the art.
illtered‘ air is fed into the concentrator through
Referring now to Fig. 3, a continuous type quick
freezing apparatus is shown diagrammatically. 5 supply pipe 56 to impart turbulence to the milk
and to evaporate water from the milk. Skim milk
'I'his device comprises concentric tubes, the inner
is added` to concentrator 60 from time to time to’
tube being indicated by 40 and the outer tube by
maintain-the liquid level at 63 to compensate for
4I. A refrigerating jacket 42 surrounds the outer
evaporation.
tube. The space between tubes 40 and 4I com
The apparatus is so designed and the method
municates with a feed hopper 43 having 'a remov 10
so conducted that the temperature’ of the milk'in
able cover and havinga pipe 44 connected to a
the concentrator 60 will rbe about 143° F. and the
suitable source of compressed air (not shown).
milk is held at this temperature for at least thirty
The space between tubes` 40 and 4I also communi
minutes so that pasteurization is obtained at the
cates with a discharge conduit 45 discharging
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into a receptacle 48. A branched feed pipe 41 15 same time the water content is being reduced.
The concentrated hot skim milk and hot cream,
supplies refrigerant, such as brineor ammonia, to
in the same relative proportions as they occurred
the jacket 42 and -to the inside of pipe 40v and a
branched outlet pipe 48 carries away the refriger
in whole milk, are then re-mixed in' a suitable l
ant, as will be understood by those skilled' in the
mixing tank, after which the hot mixture is sub
20 jected to an intense'and severe agitation to thor
oughly emulsify the mixture by breaking up the
fats and solids. Any suitable commercial homo
ferred concentrator will now be described. The g
genizing machine, such as a homogenizer or vis’
hot Water-air blow type concentrator comprises
colizer, may be used.J The term “homogenize"
an‘ open top tank 60 having a suitable water jacket
6I. 'I‘he skim milk is fed into tank 80 from a suit 25 and its derivatives are used hereinafter and in
art.
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Referring to Fig. 4, the structure of the pre
able container 59 through Vsupply pipe 62. The
the claims to describe this thorough emulsifying
level of the skim milk is kept at level indicated by
After the emulsifying operation, the> hot con63 by supplying additional skim milk as the wa
centrated homogenized milk, which may be at
ter is evaporated. The milk level isvobserved by
a glass 54. The concentrated skim milk is drawn ‘30 substantially 143° F., is fed directly to a' quick
freezing apparatus, as for example, into the pipe
off through outlet pipe 55. ,
I2 in Fig. 1, the hopper 25 in Fig. 2, or the hopper
Disposed within tank 80 is an air pipe 56 to
43 in Fig. 3. Or, the hot homogenized milk >may
which is connected a supply of filtered air gen
be first cooled to rooml or tap water temperatures
erated by a suitable blower. The air pipe 56 opens
up near the bottom of the tank so that air is 35 before subjecting'it to the quick freezing opera
tion in the above machines. In the event the
blown into the bottom of the liquid suitably agi
tating the liquid and bubbling through it, escap-'l
hot milk is ñrst cooled before subjecting to quick
freezing, it is preferable that it then be fed to
ing from the open top of the vessel.
,
operation.
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the quick freezing apparatus after cooling with
Also located in the tank 60 is a hot water coil
51 having an inlet pipe 58 and outlet pipe 64. In 40 out undue delay since if the hot milk is cooled to
let»l pipe 58 is‘sùbplied with hot water by a pump
below about 100° F. and allowed to stand, there`
`is a tendency for the milk sugar to crystallize,
50 receiving Water from a hot water heater 5I.
Outlet pipe 64 leads back to‘ the hot water heater.
forming undesirable large crystals.
.
A connection 52 connects inlet pipe 58 with the
In Fig. l1, the concentrated milk and cream is
water jacket 6I and a connection 53 connects the 45 fed through a pipe I2 into the space between the
f water jacket 6I with outlet‘pipe 54.
cylinders as indicated, this mix being spread upon
The hot water and milk pass through the pipes
'the cylinders in a thin layer and carried around
as indicated by the arrows. Hot water is circu
as they rotate. Suitable refrigeration is applied
lated through the ,hot water coil 51 and through
inside the rotating drums I0 ’and II and the en-the water jacket 8| to keep the milk in the tank 50 tire process may be carried out in a refrigerated at the proper temperature, but without overheat
room. 'I'he liquid milk quickly freezesv in a thinS
-ing it.
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layer on the surface of the drums where lt is
scraped oil by scrapers I4 and I3, the scraped
The process for preserving wholemilk will now .
" milk snow being collected by any desirable'appa
be described. The cold fresh whole milk, as it is
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obtained from the farmer, is first fed to a suit 55 ratus and compressed into cakes.
able cream separator for separating the whole
f In Fig. 2, the batch of concentrated milk- and
milk into cream and skim milk. It is desirable
cream is fed into the hopper -25 to charge the
to produce a. cream having 40% butterfat ,by
cylinder 20, after which feed valve- I8 is closed.
weight. This removes substantially all the but-.
The scraper blades 23 continually expose the 'difterfat’from the milk. The creanr is then trans 60 ferent parts of the mix to the cold refrigerated
ferred to a cream storage vat where itis pasteur
walls until the entire >mix is frozen to the proper
consistency. The overrun normally present whe'n
ized by any suitable pasteuri'zing process, The
freezing ordinary icecream is considerably re
skim milk, _from which substantially allthe but-A
terfat has been removed, is separately taken> to
duced by minimizing the whipping action, by the
any concentrating device -for reducing, but not 65 omission of swelling agents and by freezing a lit- ,
eliminating, the water content. The yconcentra
tie but more than ordinary ice cream.
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tionis»,y carried on preferably by a hot water-air
‘ When sumciently frozen, the valve 21 is opened
blowA concentrator shown in Fig. 4 where the skim
and the- action ‘of the helical Scrapers` 2l dis
milk-_isflsubjected to elevated temperature without
charges the mix into the receptacle 28. The con
cooking'v
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„Referring now to Fig. 4, the skim -milk is led
t'o vtank 59 and thence to the hot water-air blow
concentrator 60 through inlet pipe 82. The tem
perature of the hot water flowing through the
70 sistency of the discharged material may be about `
as thick as dough. The illled receptacle 28 may`
then be taken to the hardening room for fur--
ther hardening under reduced temperature. 'I'he‘l
pre-freezing so sets the material that no further
jacket BI and through coil "should not exceed 75 crystal `growth takes place in the hardening room.
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simplicity, that the proportions of `water to Lbe.
'In Fig. 3 the concentrated milk- and cream is
fed- into the feed hopper ß and sufficient com
added to the frozen product be whole numbers
and not fractions. For example, it is desirable
pressed air is supplied to pipe 44 to insure/fan
that the concentration be such that it l_is only
even flow of the mix through the machine. 'I‘he
passage of the mix between pipes 46 and Il in-
necessary for the consumer to add, say, two parts
of water by volume for each part by volume of
` a very thin layer of say one-quarter inch in thick
frozen product. To obtain a frozen product re
ness quickly freezes the mix under pressure. The
quiring such a proportional addition of water, it
freezing is so rapid that the crystals formed are
is necessary that the concentration ratio 'of skim
not much larger than moisture in air in the form
of mist, making a very fine texture. By adjust 10 milk be approximately 3.86 to l.- This ratio is
ing the amount of air, the overrun may be closely ' based upon a whole milk testing approximately
3.8% fat by'weight and allows for change in
controlled so that the frozen product has little,
-volume of the frozen product due to freezing and
if any, air added, insuring a product of maximum
density. By the time the material reaches the
Consider for example a run of 360 quarts (9
discharge pipe 46 it is properly frozen and this 15
compressing.
material 4falls into a suitable container 46.
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cans) of whole milk containing 3.8% butterfat
The f
container 46 may then be taken to a hardening
room for further hardening under reduced tem
perature. Due to the fine texture of the mate
rial, no further change in crystal structure takes 20
content by weight. This quantity of such milk .
contains about 29.05 lbs. ofy butterfát or about so
place in the hardening room.
The quick freezing process spreads the con
quarts. subtracting the 36 quarts of cream from
the 360 quarts of whole milk, we have 324 quarts
of skim milk. Concentrating the skim milk in a
ratio of 3.86 to 1 gives about 84 quarts of concen
centrated mix into a large area subjecting small
trated skim milk. Adding the 36 quarts of cream _
' unit quantities to very low refrigerating temper
and the 84 quarts of concentrated skim milk, we
.atures The temperature of the refrigerating ap
have 120 quarts of mixed milk and cream to Ibe
paratus may be as low as -'40° F. to insure quick
subjected to the homogenizing and quick freezing
freezing of the product. 'I'he milk snow obtained
-process above described. It will be noted that _'
from the apparatus of Fig. 1 may be in the form
the original 360 quarts of whole milk bears a
of a thin loose, frozen, dry powder. This may
volume ratio of 3 _to 1 to the 120 quarts of re
then be suitably compressed into cakes or bars. 30 mixed product.
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'I‘he frozen product obtained from the machines
The frozen cakes or bars may be marked or
of Figs. 2 and 3, after being subjected to the cold
otherwise indicated according to the'number of
room, may be suitably cut into cakes or bars of
parts of water by volume to be added to each part
the suitable size.'
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The preferred temperature for pasteurizing the
milk and cream is around 143° F. which is re
garded as a good pasteurizing temperature.
However, in some cases, the pasteurizing tem
peratures may run from as low as 140° F. to as
high as 165°r‘.
The temperature of the quick freezing appa
of frozen product. Or, the' frozen products may 35 indicate the amount in liquid measure of recon
- stituted whole milk which can be made _from the
particular bar or part thereof so that it 1s only §
necessary for the consumer to place a cake or
part thereof in a container of the indicated liquid
40 measure and fill with water. '
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It will be understood that the frozen product
ratus should be as low asl-40° F. to insure the
may be compressed in any desirable‘shape and
product being frozen with sufñcient speed. It is
shipped in any desirable container. For example,
desirable that the product quickly attain a tem
the frozen product may be shipped in small car
perature at least as low as '-10° F., although in 45 tons of convenient size to fit into the freezing
some cases it may be desirable to have the product
compartment of a household mechanical refrig
quickly reach a somewhat lower temperature.
erator. It is obvious also that the consumer may ‘
In other cases, it may be suilicient for the tem
perature to reach zero F. quickly.
add any’lesser amount of water than that neces'
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sary to provide reconstituted whole milk and> ob
The cakes or -bars may be of any standard size, 50 tain a heavier product corresponding, vfor ex
, depending upon the consumer demand. For ex
ample, to fresh condensed milk or whipping or
ample, the cakes or bars may be of such size that,
coflîee cream.
when mixed with a predetermined amount of
~ Thus, there -is` provided a preserved milk in
water, they will produce a half pint, pint, quart,
gallon, etc. The cakes or bars may be formed in 55 frozen, concentrated, form which, when mixed
with water, forms a reconstituted whole milk
comparatively large sizes suitably grooved or di
vided so that parts of the desired size _may be
conveniently broken off.
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' The amount of water to be added by the con
-__which has'all the ñavor, body, appearance, con
sistency and digesta-bility of original fresh natural
whole milk.
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The separation of cream ofhigh butterfat con
sumer depends upon the amount of concentration 60 tent
prior to the concentrating step preserves the
in the concentrating step and may vary consider
volatile light oils and flavors which would be'
ably. It should be borne in mind that the more
lost if the cream were subjected to the concen
water eliminated in the concentration step, the
trating process. At the same time, the use of a
more water will naturally have to be replaced by
hot water-air blast type of concentrator, no part -'
the consumer to get a true reconstituted whole
of which has a temperature highery than _170° F..
milk. The amount of -water eliminated will de
prevents cooking or `scalding the skim milk even
pend upon commercial considerations.briefly and thus does not caramelize any of the
In practice, the amount ofI concentration of
milk sugar or boil any of the proteins.
skim milk may run from a ratio as small as 21/2
The homogenizing of the milk and cream while
to l to a ratio as high as 4 to 1. The concentra Tl)
tion ratio is defined as the ratio by volume of a
given amount of skim milk before concentration
to the _volume occupied by that milk after con
centration.
In reconstituting the milk, it is desirable, for
hot thoroughly breaks up thefats and solids into
extremely ñne particles and the solid particles`
become encased in fat, which prevents any change
in their form, so that on dissolving in water, the
75 solids stay in suspension readily and there is no
` atrasos
tendencyto form nne cuçds.' or for the fat to .
clump.
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contacting the skim milk with a surface having
an applied temperature not exceeding about
170° F. while blowing a column of air in contact
,
,The immediate cooling of the homogenized mix
ture to room temperature and the immediate'
with ythe skim milk for a period of at least 30
Ifreezing prevents the milk 'from thickening and ' ' minutesto pasteurize the skim milk and to reduce
quick- ~ the Water content to le'ss than one-half by
the milk sugar from crystallizing. The
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freezing ofthe homogenized product prevents the
volume, remixing the pasteurized cream and conf
growth of large crystals so that, when the` frozen
. cent1-ated skim milk, homogenizing the hot milk
_ product dissolves, it mixes readilywith the Water,
mixture to breakup the fats and solids and to
" forming a good colloidal suspension‘having ap
cause the' solid particles to become encased in
pearance and taste entirely like the original whole
fat,4 immediately reducing the temperature of
milk.
the homogenized mixture to tap water or normal
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' Thus a method of preserving milk products. .
~ has been described which >preserves the product
room temperature, `quick-freezing the mixture
_without affecting the flavor or digestability. Due 15
tothe elimination of; roughly, two-thirds of the
water, great savingA in, space and weight is
ç eiïected, which is important for transportation
and storage.` Due to the fact that the product
is frozen, inexpensive containers, such as -waxedl 20
cartons may be used. Due to the wide distribu
tionand sale of ordinary frozen food products,
the frozen milk products can be distributed afnd
centrated whole milk, and forming said frozen
without further delay to obtain a frozen con
concentrated whole milk into shapes.
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3. The method of making a frozen whole milk
product from which a reconstituted whole milk
may be made by adding water, said method com
prising separating fresh whole milk into cream
and skim milk to produce a cream of about 40%
butterfat content by weight, separately pasteuriz- ~
ing the cream, contacting the skim milk with a
sold without difficulty since the same distribut
water heated surface of an open top concentrator
ing apparatus and technique may be used for 25 whose water has a temperature not `exceeding
the frozen milk products, as with other frozen
about 170° F., While blowing a column of air
food products now on the market.
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through the skim milk for a period of at least
- While‘certain novel features of the invention
30 minutes to pasteurize the skim milk and to
have been disclosed and are pointed out in the
reduce the water content so that the volume of
annexed claims, it will be understood that various 30 the skim milk before concentration to the volume
omissions, substitutions and changes may be
after concentration bears the ratio of between
made by those skilled in the art without. depart
ing from the spirit of the invention.
What is claimed is:
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21/2 tool and 4 to 1, remixing the> pasteurized
cream and concentrated skim milk, homogenizing
.
` the hot milk mixture to break up the fats and
1. The method of making a'frozen whole milk
product from which a reconstituted whole milk
may be made by adding water, said method com
prising separating fresh whole milk intovcr/eam
Isolids and to cause the solid particles to become
encased in'fat, reducing the temperature of the
_ homogenized mixture from above about 100° FJ -
'and skim milk, subjecting the cream to a »sutil
to normall room or tap water temperature with
out delay, -quick-freezing the mixture without
ciently high temperature to'pasteurize it without 40 furtherY deïlay to quickly bring the mixtureto a
removing volatile matter, subjecting the skimy
temperature of between zero and minus 40° F.
milk to pasteurizing temperature to reduce the- \ ‘to obtain a frozen concentrated whole milk, and
water content in a concentration ratio by volume .
forming said frozen concentrated whole milk into
' of between 21/2 to l and 4 to 1, homogenizing theA
_hot concentrated milk and cream together to 45
shapes.
4. The'inethod of making a frozen whole milk
product from whlch'a reconstituted whole milk
the homogenized mixture to' normal room on tap ' may be obtained by adding water, said method
‘ water temperature and subjecting the mixture ’
comprising separating fresh whole milk into
without substantial delay to a sufiici‘ently low
50 cream and skim milk, pasteurizing the cream,
temperature to quickly bring the mixture to a
separately concentrating the skim milk to re)
temperature of between -zero and _40° F. to form
duce substantially the water content,` mixing the
the frozen whole milk product.
said pasteurized separated cream and said con
2. The method of making a frozen whole milk
trated separated skim milk, homogenizing the
product from which a reconstituted whole milk 55 re-mixed milk, and quick-freezing the re-mixed
may be made by adding water, said method com
homogenized milk to form the frozen whole milk
product.
y
prising separating fresh whole milk into cream
f and skim milk, separately ,pasteurizi'ng the'cream,
,
CHARLES BRUNKHURST.
break up the solids, reducing the temperature of
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