April 13, 1948.
D. D. PEEBLr-:s Er AL
PROCESS FOR MANUFACTUÈE
2,439,612
MILK SUGAR
Filed Se‘pt. 28, 1942
2 Sheets-Sheet 1
April 1;-, _1948.
o. D. PEEBLAES er AL
2,439,612
PROCESS- FOR MANUFACTURE O'F MILK SUGAR
Filed Sept. 28, 41942
`
2 Sheets-Sheet 2
@m
ArroeA/ÈY
"Patented ~Apr. 13, 1948
" 2,439,612
UNrrEosTA'rEs Hiram'N ortica
N
q. David D. Peebles, Hillsborough, _and Thomas V.
` Marquis, Santa Cruz, Calif., assignors to West-`
ern Conilensing` Company, San Francisco,
l Calif., a corporation of California
‘
Application september 2s, 1942, sei-1eme. 459,9zo
8 Claims. (Cl. 12V-31)
1
` ,
other insoluble contaminants during crystalliza«
This invention relates generally to processes for
the manufacture of milk sugar or lactose from
liquid Whey.
,
`
tion.
process of the above character having a novel
Conventional processes for the manufacture of
procedure for effectively separating out lactose
lactose from whey are carried out as` follows: A
portion of the protein of the whey is coagulated
by `addition of lime and application of heat, or
by the addition of other coagulants, after‘which
the coagulated solids together withprecipitated
crystals after the crystallizing operation, and ‘
which minimizes the percentage of contaminants
` removed with the crystals, and also minimizes
resolution of lactose.
calcium phosphate and other insoluble solids are 10
‘ removed by decantation, ñltration or centrifug
ing. The clarified eliluent is then concentrated by
evaporation, and lactose is `crystallized from the
concentrate. Lactose is then removed from the
` mother liquor by` centrifuging and further puri
,.
Another object of the invention is to provide a
‘
l
l
`
`
Another object of the invention is to make pos
sible the preparation of a relatively pure `lac
tose by crystallization from a iacteal` concentrate
to which no chemicals like mineral acid have been
added.
c
‘
ñed by washing. Processes of thischaracterdo
A further` object offj the invention is to provide
a process making `possible the manufacture of
not produce a lactose as pureas desired or as can
milk sugar from raw whey. while at thesame time ‘
15
affording a valuable food product from the >re-.
be obtained by the prcsent‘invention, and nutri
tive constituents of the whey solids, other than
the recovered lactose„are seriously impaired or
destroyed.
„
.
r
`
Some lactose has also been manufactured by
` ‘crystallizing from a concentrate of a lacteal ma
.maining ingredients.
zo
Referring to the drawing: ,
-
Figure 1 is a flow sheet illustrating one pro
cedure which can be followed in carrying 'out the
present invention: and
,
Figure 2 is adiagrammatic view showing h terial like skim milk, but Without previous re
‘movval‘ of proteins. In such a process, however, 25 draulic classifying apparatus suitable for use in
separating out lactose crystals.
the proteins' of the lacteal fluid are purposely held
Flgures`3, 4 and 5 are curves showing‘the eiîect`
" in solution or a‘state of colloidal dispersion and
of our special heat treatment.
remain so during'the re-crystallization of the lac- ~
In carrying out the present process we evapo
tose and its subsequent separation. The process
has not proven satisfactory (see Fundamentals of 30 rate whey `to produce a concentrate which is
Dairy Science; Rogers, 2nd edition, page 129), ` supersaturatedwith respect to its lactose content.
the difficulties encountered being attributed to
contamination of the crystals with protein. Ac
By means of special heat treatment the concen- t
of relatively pure lactose by crystallization from
sequent _evaporating step I2. The temperature
trate is caused to have certain properties-which
we have found-to be conducive to the production
cording to our observations such a process is im
practical because the crystals formed lack such 35 of relatively large and fast settling lactose crys
tals in the/subsequent crystallizing operation. A
` uniformity and size as is required for eiîective hy
'part of the lactose is permitted to crystallize out
draulic separation, centrifuging, and washing.
In `another process which has been `usedto` ‘ of the concentrate, and this mixture is then sub- `
mitted vto hydraulic classification for removal
some extent, the coagulable protein is not re
of the lactose crystals. This last step is pref
moved prior to crystallization, but is enzymically
erably aided by diluting the concentrate with a
degraded to molecularly‘smaller `and less readily
cool `diluen-t like water. `Finally the removedA lac
coagulable `substances in order that crystalliza
tose can be centrifuged and washed.
tion and subsequentoperations may take place in
The procedure shown in Figure 1 is as folli ws:
a fluid relatively ‘free of insoluble contaminants. 45 l'A suitable raw liquid material, such ,as einer
Such a process is relatively expensive to carry out
cheese or casein whey, >or a mixture ofthe two,
commercially, it is critical with respect to pH vcon
is preheated at l0 and is then momentarily he ated
trol, and it requires addition of a chemical like
to-an elevated temperature at ll. The heating
hydrochloric acid which is later neutralized.
`
at I I‘can be conveniently carried out by direct in
It is an object of the present invention to pro 50 troduction of live steam into the preheated ma
víde a process making possible the manufacture , terial„as this material is being pumped to the sub
to which the material is heated is preferably in
excess of 212° F., and a suitable range is from 220
agulated proteins. and without any treatment to
prevent the presence of coagulated protein or 55 to 260° F. After being abruptly heated to such
e, concentrate, without previous removal of co
9,439,612
an elevated temperature by direct contact with
dures only- one
4"
piece of equipment is used for the
-the steam, the material immediately proceeds to
the evaporating step l2 where the evaporation is
preferably carried out under vacuum, in suitable
vacuum evaporating equipment. As the material
passes `to the ñrst evaporating stage, it immedi
flash heating.
Following production of the concentrate, which
is characterized by the absence of lactose crys
tals, and which contains a particular type of
ately- flashes to a lower temperature below 212°
F., and such relatively low temperatures are main
tained until evaporation has been carried out to,
a suitable degree. The heating at l i is for a short
interval, and will not discolor or otherwise det- `
ter in a finely divided state, the concentrate is
subjected to the crystallizing operation l5. This
can be carried out in suitable crystallizing tanks,
coagulated protein as well as other insoluble mat
rimentally aiîect the whey soli .
It is desirable to carry out evaporation until
the concentrate containsfrom, say, 50 to 55% `
solids. At such concentrations there is a tend
ency for small crystals of lactose to form in the 15
evaporator. We have found that their presence
detrlmentally affects the process, presumably be
cause their small particle size prevents properly
where the material is permitted to remain for a. i
period of time sufficient to permit the develop- `
ment‘of lactose crystals. During crystallizing,
gentle agitation is desirable, and it is also desir
able, but not necessary, to subject the material to
gradual cooling. For example, in a typical in
stance the concentrate may be received in the
ycrystallizing tanks at a temperature of about 110'
F., and during crystallization it may be cooled to
a temperature of the order of 68° F.
controlled crystall formation during the crystal
In
order
to
reduce
the
crystallizing
period,
and
20
lization step and hinders subsequent separation,
in order to facilitate production of relatively
centrifuging and washing.` To eliminate such
large, fast settling material, it is preferable to
small crystals, we pass the concentrate through a.
s‘eed fresh concentrate -With material which has
heating step I3, like step il, and where the con
been treated in the crystallizing tanks. Thus'at
centrate is momentarily heated to an elevated
temperature such as from 220 to 260° F. by direct 25 the end of the crystallizing operation, one `can
remove only a part of the batch of material (such
as 25 to 50% of the total mass undergoing crystal
heating, the concentrate can rapidly passl through
i contact with steam. Immediately following such
one or more final stages of evaporation at I4 to
cool it to a temperature of the order of 110° F.,
and to complete evaporation.
Steps Il and 'i3 can be carried out by the use
of relattively simple equipment. For example,
one can -malle use of a small cylindrical cham
ber about 14 inches long,.and about 3 inches in
` dlameten-’with a stream of whey entering one
end and leaving the'other. Live steam at a pres
sure above atmospheric is introduced tangentially
into the chamber near the point of introduction
of the whey. The flow rate through the cham
ber should be such as to afford only momentary
or flash heating to the high temperature, as for
example a time period within the chamber of.
from 2 to 5 seconds. The discharge of this cham
so
lization) , leaving the remainder to intermix with
and seed a succeeding batch of concentrate.
,
Another procedure which can be used for the
crystalllzing operation is as follows: An initial
batch of concentrate is crystallizedover a suit->>
able period such as 24 hours. ~ Without removing '
any of the initial batch, it is mixed with the next
batch of concentrate, and the combined material
is further crystallized for a like period. `A third‘
batch of concentratev is then added and crystal
lization continued.` as with they second batch.
Further additions of concentrate can be mad
dependinggupon
The material the
removed
tankage
from
capacity.
the crystallizing
`
operation is diluted at I6, preferably with rela.
tively cool water. For example, assuming that the
material being withdrawn from the crystallizing ‘
ber is led lby piping directly to the expansion 45 tanks is at a temperature of the order of 68° F.,
chamber of the’vacuum evaporator.
the water used for dilution is preferably relatively ,
The preheating step .l0 is not essential but is
colder, `as for example a temperature of 60° F.,
, desirable in order- to avoid too great a dilution
or lower. The extent of the dilution may vary,
although in a typical instance from 25 to’50 gal
ation Il. Preheating is preferably carried out-to 50 lons of waterv can be used to dilute 100 gallons
a temperature of the order of, say, 180 to 190° F.
of concentrate, depending upon vthe nature of the
by use of suitable heating apparatus such as one
concentrate. In place of plain waterfother aque
by steam condensate in the heat treatment oper- \
using heated tubes through which the liquid is
rapidly circulated.
`
ous materials can be used, such as whey.` Dilu- ,
tion in this fashion serves the useful purpose of
The type of vacuum evaporating equipment 55 reducing the viscosity of the material, aswell as
utilized can vary in practice, although I prefer
reducing its density, thus putting the material
to utilize equipment of the type disclosed in
in better condition for subsequent separation of
Peebles et al. Patents Nos. 2,090,985 and 2,168,362.
the lactose. Dilution may not be important
Such equipment is characterized by rapid flow of
under certain ideal conditions, that is with rela
the material through the evaporating effects, and 60 tively low viscosity'and exceptionally large crys
by the fact that prolonged-heat treatment is
tals. However, such ideal conditions can be ob
avoide'd.
I
.
'
>
tained only infrare instances.
»
The-separating operation i1 upon the diluted
In place of the procedure described above, a
Asingle unit of evaporating equipment can be em 65 material should remove the lactose crystals from
contaminants and mother liquor without seri
ployed with, say, two or more evaporatin'g effects.
After the maior part of the evaporation has been f ous re-solution. It will be noted that because of
dilution, the liquid is not saturated with respect
completed, the concentrate can be passedl back
to its dissolved lactose content, and therefore re
through the flash heating operation I I. and then
repassed through the evaporating equipment for 70 solution of the crystallized lactose can occur. 'I_‘he
rate of solution of lactose as well as its solu
the operation Il. Also it is feasible to continually
bility
decreases with decrease in temperature, and
recirculate a batch `ofvwhey through and in series
therefore use of cold `diluting water lowers the
with the flash heating equipment and evaporat
temperature of the material and tends to mini
ing unit, until the degree of concentration desired
has been attained. In both of the latter proce 75 mize re-solution in the separating operation.
Various types of separating methods can be
`
‘
5
for removal of the lactose. although hydrau
turn is -caused to a substantial degree by the pres~ '
ence of partially coagulated protein particles,
lic `eiassiilcation is preferred. One desirable form
of apparatus for carrying out hydraulic> classifi
_ ` which have considerable water of hydration and
> cation will be presently described.
. which increase the viscosity of the concentrate
'I'he lactose crystalsremovedby hydraulic sep
5 becauseïof their jell-like character. When‘whey
aration carry a minimum of proteins and other
is concentrated by ordinary vacuum evaporation
contaminants, and they can be directly subjected
to from 50% to 55% solids, only about 50% to 52%
to centrifuging at I8. During centrifuging. `the
of the protein is coagulated and the protein par
lactose is subjected to washing withfresh water i
ticles are caused to have a relatively large curd
for further puriiication. The lactose 4as i‘lnaliy l0 volume. Our special heat treatment, by momen
removed from the basket of the centrifuge con? tary heating to a, high temperature, serves to ir
tains ífromlabout 3 to 10% moisture and can be
reversibly coagulate substantially all ofthe pro
subjected to drying at I9 to produce the ilnal
tein which is readily susceptible to coagulation
dried product.
‘
`
y
.
by heat treatment, namely to the extent of about
^ The eii'iuent from the separating operation I'I 15 60% to 62% of the total protein content.
y contains valuable food ingredients. including wa
By irreversible coagulation we have reference
to such denaturing of the coagulated protein that
ter soluble >'vitamins like riboñavin and other
members of the vitamin IB complex, and is uti
the protein particles do not subsequently imbibe
lized to form a saleable by-product.
Thus the `
overflow from the separation operation I1 is
i water -or hydrate to enlarge their relative curd
o volume. During such denaturing there is a sub
stantial shrinkage in the particle size of the pro
. shown being subjected to drying at 20 to pro
duce a final dried product. Such a material is
'useful' as an ingredient in stock or poultry feed.
tein, and this shrinkage is accompanied by a loss
of water of hydration.
Y
Figure 2 diagrammatically shows a desirable
The curves shown by Figures 3, 4 and 5 serve
apparatus for carrying out the diluting and sep 25 to illustrate the effect ,of the special heat treat
arating steps I5 and Il. This equipment includes
ment. In Figure-3 curve I represents the extent
a classifying cone 2l having an inlet pipe 22,
of coagulation of protein as concentration pro
an overilow launder 23, and an outlet pipe 24.
ceeds, using a single vacuum evaporation unit
in series With a high temperature ilash heater
Pipe 26 connects with pipe 22 for introducing
cold- water, and the discharge end of pipe 22 is 30 as previously explained. Curve 2 represents the ,
surrounded by the collar 2l. The bottom of the
extent of .proteincoag'ulation where the whey is
cone is provided with a discharge opening nor
simply pre-heated _to about 180° F. and then con
mally closed by the hinged trap door 29.
.
centrated by vacuum evaporation at treatment
In operating the apparatus -ofFigure 2 and to . temperatures of the order from 125 to 130° F.
carry out our preferred process, concentrate en
35 Note that, at about 27 Bé., corresponding to labout
52% solids, the percentage of coagulation shown
tering pipe 22 is diluted with" cold water or whey,
and as the diluted material enters the cone, lac
by curve I is about 62%, while it isonly about
52% for curve 2. According to our_observation
tose crystals settle out and collect as a bed in
the lower part of the cone. From time `to time
it is impossible to coagulate more than about 65%
door 29 is opened to withdraw lactose from the 40 of the whey nitrogen as protein, by heat treat
bottom of the bed, or if desired the cone may
ment. The uncoagulated protein remains in sol
be completely filled with lactose crystals, the re
uble form. Curves 3 and 4 in Figure 4 show the
sidual ei'iluent containing contaminants drained
relativecurd volume for the lcoagulatedi protein
off, and the entire batch of crystals droppedinto
in the concentrates corresponding to curves I
a suitable tank. The material is then taken from 45 and 2. Note that at about 27 Bé. the curd volume
this tank for centrifuging and washing. The
overflow carries off substantially all of the re
»of the coagulated protein (curve 3) obtained by
use of the momentary high temperature treat
ment is substantially less than the curd volume
maining solids, including the finely divided co
agulated protein. With apparatus of this char
of protein obtained by ordinary evaporation
acter, re-solution of the lactose is maintained at 50 (curve I). This means that for a given concen
tration the whey made by the present process
a minimum. particularly because as the lactose
settles to the lower bed of crystals. it is immedi
has a substantially lower viscosity than concen
ately covered and protected against re-solution
by subsequently settling solids, and because the
quiescent liquid in that part of the cone-occu
trate made by ordinary evaporatiomby virtue
of the smaller curd volume' of the coagulated
55 protein.
condition of saturation with respect to lactose
in solution.
~
,
‘
Figure 5 shows the enect of the heat treatment
upon the water imbibing properties of the coagu
pied by the collected bed of crystals assumes a i
lated protein. Curve `5 of this ñgure shows how
f
A particular feature of the above process is
the coagulated protein of whey prepared by our
the speciall conditioning of the concentrate used 60 process does not imbibe water to any appreciable
' for the crystallizing operation, to make possible
extent upon prolonged holding, while curvel 6
relatively large crystals `of lactose, having aV high
settling rate and capable of being handled with
shows that the coagulated protein corresponding
to curve 4 does imbibe water to a substantial de
gree upon prolonged holding. The effect» of this `
trate containing 50% to 55% solids were prepared 65 would be to increase the 'viscosity of the concen
out difficulty in a centrifuge. If a whey concen
by ordinary vacuum'evaporation. with or without
preheating .as previously described, and if one
'then attempted to crystallize out lactose from a
trate during the prolonged holding period which
- occurs inthe crystallizing operation, while on
the contrary with'the irreversible coagulated pro
concentrate obtained in this manner, the lactose
tein obtained by our process,` the viscosity im
crystals would lack uniformity as to size> and a 70 parted by the protein remains constant while the
substantial part of the crystals wouldV be'so small
that they could not be readily separated out, cen
trifuged,and washed. We have found that this
is due to a substantial degree to the relatively
high viscosity of such a concentrate, which in 75
lactose is being crystallized. thus promoting the
production of large-size and uniform lactose
crystals as previously described.
A low viscosity for the concentrate is also de
sirable in that it aids evaporation to the concen
2,439,612
8
tration desired, particularly in that an increasey
mass after such seeding, and then separating out»
lactose crystals _from the mass of material.
:ln viscosity tends to make handling in a vacuum
evaporator more diilicult and the evaporating
cycle less eillcient.'
l
‘
2. In aprocess for the manufacture of lactose,
l
the steps of forming a lacteal concentrate super
saturated with respect to its lactose content and
In a typical instance the whey `introduced into
the process had about 6.05% solids, and the solids
analyzed substantially as follows:
Per cent
`
Acid
(as lactic)
____ __' _________________ __
Lactose (monohydrate)
containing - coagulated milk protein, causing a
substantial amount o! the lactose content to
crystallize out of solution, diluting‘the concen
5.6
trate with water which is relatively cool com
pared to the concentrate being diluted, the
amount oi diluting water being suil‘lcient to eiïect
___ _____________ __ 67.0
`Protein ________________________________ __ 14.3
______ _
10.0
Undetermined ______________ __ ________ __
Ash
`
3.1
ì
a substantial reduction in viscosity and the tem
perature of the diluting water being sufilclently
At the end of thecrystallizlng operation, from ' ' llow to minimize resolution oi lactose upon dilu
tion, and immediately thereafter removing lac
tose crystalsI from the diluted material by hy
a 52% solids concentrate. the material contained
about 19.0% of crystallized lactose. Oi the total
lactose content of the original whey, about 35%
draulic classification.l
yevaporation to form a supersaturated solution oi
" lactose, permitting asubstantial amount of the
overilow contained about 76.6% oi’ the total solids .
-
lactose content to crystallize out from the solu
tion, adding water to- the bulk of the material
'
The lactose after centrifuging and drying
analyzed as follows;
containing the crystals to an amount sufficient ìto
effect- a substantial reduction in viscosity, the
water being relatively cool compared to the con
Per cent
Moisture ____ _________________ ___.’ ____ __
0.03
Protein
Ash
’
_____
0.22
Lactose _______________________________ -_
99.17
Acid
„
0.49 '_
,
_
_
`
centrate being diluted to minimize resolution of
lactose in the diluted mass, and then removing
lactose crystals from the diluted material by hy
0.09
draulic classification.
The dry> feed material made by drying the
from lacteal material containing milk protein
and lactose, subjecting' the material to evapora
7-3
tion and heat treatment to form a concentrate
supersaturated with respect to its lactose con
tent and completely free from lactose crystals,
_ 18.7
the major part of the protein concentrate being
Per cent
Acid
~
`
__ 57.5
-
Protein
'
4. In a process for the manufacture oi lactose
overñow from the classifier analyzed as follows:
Lactose
ì
from whey, the steps of concentrating whey by
trifuging. The feed product made by drying the
in the original whey.
'
Í3. In a process for the manufacture of lactose
Was removed from the lower end of the classifier,
and about 34% remained after washing and cen
lrreversibly coagulated, seeding a mass of the
concentrate with lactose crystals formed in a
40 previous crystalllzing operation of the process,
It will be apparent that the products' obtained
permitting lactose crystals to form in the seeded
will vary in analysis from time to time, depend
mass,.diluting the mass of material with water in
Ash
13.0
Undetermined _________________________ __
3.5
ing upon various factors such as the character
an amount suiilicient` to effect a substantial re
of the raw whey employed, the preciseprocedure
duction in viscosity, said water being cool com
employed in carrying out concentration and 45 pared to the temperature of the mass being di
crystallization, and the extent, of re-solution per
luted to minimize resolution of lactose in the di
mitted in separating the lactose. The figures
luted mass, and then separating out lactose
cited above by Way of example demonstrate the
crystals from the diluted material.
high degree of purity made possible by the
5. In a process for the manufacture of lactose
process.
50
-
from lacteal material containing ì milk ‘protein
In the foregoing reference has been made to
and lactose, subjecting the material to vacuum
use of ordinary liquid whey such as is obtained
evaporation to form a concentrate supersatu
in the manufacture of cheese or casein. The
rated with respect to its lactose content, ñash`
process is also applicable to other lactose con
heating the concentrate at about the completion
taining -lacteal iiuids, such as a material prepared 55 of evaporation to a temperature and for aiperiod `
by mixing dry powdered whey with water. Such
a reconstituted whey can be‘ treated as previously
described, with modiiication oi the evaporating
operation in accordance with th'e solids content`
of the reconstituted material.
We claim:
.
l. In a process-for the manufacture of lactose
from a liquid lacteal material containing milkl
protein and lactose, subjecting the material to
evaporation and heat treatment to form a con
centrate which is supersaturated with respect to
its lactose content, >which has the major part of
its protein content irreversibly coagulated by
‘ of time sufiicient to cause complete resolution >of
lactose crystals formed during previous vacuum
evaporation, cooling the concentrate after such
heating without crystallization of. lactose, seed
ing a mass of the concentrate with lactose crys
tals, permitting lactose crystals to form in the
seeded mass, and then separating out lactose
crystals from the mass of material.
'
6. In aprocess for the »manufacture of lactoseA
from a liquid lacteal material containing milk
protein -and lactose, subjecting theA material to
vacuum evaporation and heat treatment to form `
' a concentrate which is supersaturated with re
heat and which is free of> lactose crystals, the
spect to its lactose content; which has the major
heat treatment including directly contacting the 70 part of its protein contentirreversibly coagu-`
material with steam. to rapidly v'transfer heat to
the same, seeding a mass of said concentrate with
lactose crystals formed in a preceding crystalliz
lated by heat and which is free of lactose crys
tals, the heat treatment including ñash heating „
oi’ the material to‘a temperature in excess of
ing operation of the process, permitting lactose
about 212° F. for a period ‘oi time suñicient to
from the concentrate to crystallize out in the 75 lrreversibly coagulate the majority oi' the-whey
2,439,012
l0
permitting lactose crystals to iorm in the seeded
protein but insufilcient to cause material dis
coloration oi.' whey solids, seeding a mass of said
mass, diluting the mass of material with water
concentrate with lactose vcrystals formed in a
in an amount sufficient to eiïect a substantial re
preceding crystallizing operation of the process,
permitting lactose from the concentrate to crys
tallize out in the mass after such seeding, and
then separating out lactose crystals from the
mass of material.
7. Ina process for the manufacture of lactose
from whey, the steps of concentrating whey by
evaporation to Iorm a concentrate supersatu
duction in viscosity, said water being at a tem
perature suillciently low relative to the tempera
ture of the concentrate to substantially reduce
thetemperature of the resulting diluted mass to
thereby minimize resolution of lactose crystals.
and then eiiectfng hydraulic separation oi lac
tose crystals from the diluted material, said last
named step being conducted =by supplying the
rated with respect to its lactose content. seed
diluted mass to the upper portion of a liquid sep
‘ing a mass oi the concentrate with lactose crys
arating column. establishing an overilow oi liquid
from the upper portion of the column together
tals, permitting lactose crystals to icrm in the
seeded mass, diluting the mass of material with 16 with unseparated crystals, and permitting lac
tose crystals to separate out into a lower quies
water in an amount suilicient to efl'ect a substan
tial reduction in viscosity, and then subjecting
cent portion ci the column.
\
the resulting mass to hydraulic separation to ei-\
DAVID D. PEEBLES.
. iect separation of lactose crystals, said last
THOMAS V. MARQUIS.
named step being conducted by continually sup 20
plying the diluted mass to the upper portion of
a liquid separating column, continually with
drawing an overilow consisting o1 liquid and un
. REFERENCES CITED
The following` references are oi' record in the .
ille`of this patent:
UNITED STATES PATENTS
column, and permitting the lactose crystals to 25
separate out into the lower quiescent portion oi
Name
Date
Number
separated crystals from the upper portion oi the , \ ‘
the column.
.
8. In a process for the manufacture of lactose
from whey, the steps of concentrating whey by
evaporation to form a concentrate supersatu 30
rated with respect to its lactose content, seeding
a mass of the concentrate with lactose crystals,
193,436
Witte ..... _e ..... .__ July 24, 1877
648,490 ,
Graei! ____________ __ May 1, 1900
Bell ____________ __ Sept. 2l, 1926
Leighton _______ __ Mar. 20, 1934
1,600,573
1,952,017
2,116,931
2,181,146
, Leviton __________ -_ May 10,1938
Peebles et a1 ...... -_ Nov. 28, 1939