Note: Descriptions are shown in the official language in which they were submitted.
7~3;2
This invention relates to a process Gf altering
microstructures in polydisperse aqueous systems which contain
water-soluble substances, and in particular milk.
In their original s~ate, such systems are in a state
oF equilibrium. The structures of the dispersed substances
match each other regarding ~heir solubility in water. The micro-
structure of each dispersed substance assumes the configuration
which corresponds to the quantity of water which is available.
For this reason the entire system can be described as being in
a state of equilibrium. ~Each of ~he individual systems is
also in a water-dependent state of equilibriumj.
This state can well be described, e-g-, for milk,
which is one of the most complex polydisperse aqueous systems.
Consisting of carbohydra~es, enzymes, fat, protein, salts, trace
elements, enzymes and certain ot.her substances, milk is a basic
foodstuff.
The above-mentioned nutritive substances possess a
larger number of propertiesO Some o~ these are:
- hydrophilic or hydrophobic properties;
- foam-forming, gel-forming, thickening properties;
- thixotropic, agglomerating, cross-linking properties,
- an ability to bind, form or relase substancesi
- buffering~ sweetness-increasing, sweetness-decreasing,
caramelising properties;
- odor-absorbing9 taste-influencing, flavor-activating properties;
- sour-promoting, acid-binding propertiesi
- energy-releasing, energy-absorbing properties~ etc.
,
- 'I - ~
~9~7 !31,~
Irl original milk, tn3 water-bindincJ property of
the substances dispersed in the milk is predolîlinantî all
other properties are subord:Lnate to that one property and
are not available in the aqueous stat.eO
Besides/ owiny to influences which are due to th~
feeding of animals, environmental condi.tions and an
improper treatr.lent, the water-dependent states of
equilibrium of -the .substances dispersed in polyd.i.sperse
aqueous systems may be unr`avorably altered with regard to
the processing of such systemsO
For instance, the presence of inhibitors, an
excessive water content, and an activation of enzymes can
often be detected~
Systems exhibiting the last-mentioned undesirec1
features previously had to be rejected or~ if they were not
recognized in time and were l~rocessed, involved substantial
losses in production~,
In the previous practice, systems of the kind
described first hereinbefore are -tre~ted regardless of the
states of the several dispersed substances and su~stantial
processing sequences were required to develop a certain
necessary property of a certain dispersed substance~
This will be explained with reference to the
production of cheeseO
The production o:E cheese deperlds highly on gel-
Eorming, cross-linking and enzyme forminy properties oE
proteins.
~nf~
Until recentl.y, the in-.iro system of milk,
including all systems oF the several clispersed substances,
was processed to promo-te the above-mentioned properties~
-- 2 --
~s~37~æ
~ actose and certain sal~.s as well as ~he so-called
whey proteins all had ~o be processed too although in the
water solub'e state in which thcy are present they strongly
disturb the development of the desired gel-Eormi.ng properties
of cas~in~
rrhey are then removed more o.r less in a very lata
stage of the production process~
In recent technologies, the systems are :Eirst
subjected to separatiorl processes, such as ultrafiltration
or ultrafiltration combined with other separating processes,
for instance, vacuum evaporation, so that the contents of
dispersed substances which would disturb the development of
a certain property of another dispexsed substance will be
decr~ased~
For instance, ultrafiltration processes for
producing a protein concentrate having different protein
contents or ultrafiltration processes for removing water
from the systems before their actual ultrafiltration are
known and have been adopted to provide a specified protein
concentrate regardless of th.e behavior of the individual
systems during the separating steps, their influenc2 on
each other and their properties in the concentrate.
Ir. these processes, the entire system is treated
in an entirely indiscriminate manner reyardless of the
influences of the individual systems on each other during
the processing, only with the aim to provide a specified
conc~ntrate having specified contents of individual
~ispersed suhstances, regardless whethe.r or not individual
systems can still ass~e water~soluble states and regardless
of the behavior of the individual systems can s~ill assume
-- 3 --
~L907~
water-soluble states and regardless o~ the behaviour of the
individual systems in their incidentally assumed states.
In German Opened Applications 22 11 737 and 27 46 532,
reference is made only to the protein content which can be
obtained and the final water content which is desired.
In the use of said processes it has been found that
concentrates in which the properties of the dispersed substances
have been changed arbitrarily and indiscriminately are virtually
useless because bitter substances, e.g. may form therein and
owing to the uncontrolled particle size distribution of the pro-
teins these concentrates do not permit a controlled cross-
linking of proteins.
It is an object of the invention to provide a process
by which the microstructures of dispersed substances contained
in polydisperse aqueous systems, such as milk or beer, can be
matched while the substances are water-soluble. This object is
accomplished according to the invention in,that the dispersed
substances contained in the starting material and/or substances
added to the starting material are subjected to separating pro-
cesses whereby their microstructures are altered to assume
such a relation to each other that properties of the desired end
product are predetermined in the starting material in which the
dispersed substances are in a water-soluble state.
According to the present invention there is provided
a process for standardizing the structure of the proteins in
milk, comprising: a) ~ thdrawing a portion of the milk and in-
creasing the concentration of protein constituents in said with-
drawn portion by ultrafiltration by a factor of at least one-
and-a-half; b) mixing the concentrated portion with the residual
portion of ~he milki c) concentrating the resulting mixture
by ultrafiltration by a factor oE at least one-and-a-half; d)
removing a portion of the water from the resulting concentrate
. ~ _
~ i~3
37~
by vacuum evaporation or reverse osmosis at a temperature below
65C; e) subjecting the concentrate obtained in step (d) to
-ultrafiltration; f) mixing concentrate obtained in step (e)
with the water obtained in step (d); g) subjecting the mixture
obtained in step (f) and the iltrate obtained in step (e) to a
separate heat treatment at a temperature of up to 85C; and
h) subsequently remixing the mixture and filtrate of step (g).
In the process a~cording to the invention the relation-
ship of the dispersed substances, whether they are originally
contained in the starting material or have been added thereto,
are adjusted in quantity, particle
- 4a -
7~
siæe~ water solubility and/or equilibriumO If the products
are li~uid or include the entire original solids content,
the li~uid which has been removed and which may have been
treated or may not have been treated can subse~uently be
added entirely or in part. Liquid can be subsequently
added in a c~uantity which exceeds the quantity of liquid
that has been removedO The separating ~rocesses may be
carried out at dif~eren-t temperatures or liquid may be
subsequently added at different -temperatures~ The pro-
portions of the dispersed su~stances originally containedin and/or added to the starting rnaterial can be changed by
separatin~ processes which are carried out in series or in
paralleli In a preferred embodiment of thP process according
to the invention, a preconcentrate is prepared and is then
diluted with polydispersed systems, which may have been
treated or may not have been trated, or with the starting
matexial, which may have been treated or may not have been
treated, and the resulting mixture may subsequently be
subjected to another separa-ting process and additional
steps for influencing ~he microstructures may be adopted
during the separating process, if desired, when the
substances which are to be concentrated hava reached a
concentration which exceeds their initial concentration
in the mixture or amounts to at least one and a half times
said initial concentration in the mixture. This process
may be used, e~g., to produce milk products/ For instance,
when it is desired ~o produce milk products by ultra-
filtration, a preconcentrate is prepared, which may contain
substances that are to be concentrated, such as proteins,
in twice their initial concentration, and which is then
~i~0~9~
diluted with -treated or un-treatecl rnilk, whereaiter the
resultingl~xtur~ is subjected to ultra~iltratio:n once more G
When the substances to be concentrated, such as protain,
have reached a concen~ration which is at least one and a
half times their concentration in the mixture before the
ultra~ ration, additional measures for influencir~g
micros-tructures may be carried out during tne ultra~iltra~
tion. This process may be carried out, eOc~, to make milk
products~ In tlle ~la.~ing of milk proclucts by ultrafiltration,
for insta.nce, a praconcentrate is prepared (which ~as, e~g.,
abou-t twice the contents of substances to be concentrated,
such as protein). That concentrate is tllerl diluted with
untreatecl or treated milk and -the mixture is subsequently
ultrafilterecJ. once moreO When the substa~ces to be
concentrated ~such as protein~ have reached at ]east one
and a half times their initial concentration~ additional
measures for influencincJ microstructures can b~ carried ou~
duriny the ultrafiltration~
The present invention is concerned with controlled
~0 influ~nces ex~rted on inclividual sys-tems in an overall
system. Within the scope of the invention it has been
~ound that in the proauction o~ products from said sys tems
it is desirabl to develop cer-tain properties of several
dispersed substances when these are still water-soluble so
that these properties of indiviclual dispersd substances
CaXl be utilized in a controlled manner because this will
permit the processincJ to be ca:rriecl out with a smaller
enercJy cons~rlp-tion, a ihlc~ller economy and a small-~r
pollut:ion oE the erlvironment~
In accordance with the invention, separatincJ
~907~1Z
processes known per se are carried out ~.o effect controlled,
alterations of the microstructures of the individual
systems during the processin~ in such a manner tha-t
initially latent pro~rti~s which are desired for the
processing to produce of a given procluct are ~eveloped
when the dispersed systems are still in a water~soluble
state.
For ~stance, when sXim milk is suhjected to
ultrafiltration accordiny to the state of the art~ the
protein which is present is water-soluble and its
concentration will be increased. At the same time, -the
also wat~r-soluble lactose and salts are removed regardless
of the rnicrostruc-tural state of the proteinO As a result,
tlle proportions will be chanyed as follows i~ the protein
concentration is increased 1:5.
Ratio of conten~s Ratio of contents in
in starting milk concentrate
5 parts casein to 5 parts casein to
1 part protein 1 part protein
20 0.6 part casein to 2.5 parts casein to
1 part lactose 1 part lactose
0~8 part casein to 8 parts casein to
1 part ash 1 part ash
23 parts casein to 30.3 parts casein to
1 part calcium 1 part calciwn
As a result o~ that change in proportions, protein
micelles divide -to form sub-micelles an~ the stability
of that protein is so strongly changed tha~ subsequent
process steps result in yrea-t demacJe and cannot be
optimiæecl~
-- 7 --
119(3~92
These unfavorable alterations o:E the microstruc-tures
of the substances dispars~d in milk result froM all
separa-ting processes carriea out thus F.ar because they
result in substantial c.hanges of the proportions of all
or some substances dispersed in the milk regarclless o~
their states of equilibrium and the influences thereof
on -the microstructures o~ the several dispe:rsed substancesO
Fo.r this reason the invention calls for such a
combination of separating processes that the changes in
the proportions o~ the substances dispersed in milk result
in such alterations of the microstructures of the
substances dispersed in milk that desired properties of
the end produc-t are already present in the starting product
or are so prepared therein that final states can be
stabilized.
This will be explained with reference to the
production of certified milk ~heese~ sour milk products,
fresh cheese, essences and beerO
.1) Production of Certified Milk
In the production of certified milk, a legally
prescribed heating process is required, in which states
o~ equilibrium of various dispersed substances are
chan~ed in an en-tirely indiscriminate manner; this
results in undesirea changes of properti~sO
For instance, a high-temperature hea-t treatmen-t
will result in an as-boilea taste and oxidizad taste, an
ultrahigh-temperature haat treatment will result in
carameliziny and in a lower stabili-ty o~ proteins, and
short--time heat treatment will rasult i.n a slight as-
boiled taste and in an inadequate sterilization.
~ a~
~,~ ~r ~J~
For this reason the invention provides a process
o:E exerting a controlled influence on the microstruetures
of disper~ed substan~es by means of known sepaxacing
processes, whieh are systematically carried out to exert
such an influence on individual structures that a subsaquent
heat treatment will not result in uncontrolled ehanges of
proparties so that, e~g~ 9 undesired chanyes o flavor will
be avoidedO
If the starting product is a satisfactory oriyinal
raw milk, whieh is to be subjected to an ultrahigh-tempera-
ture heat treatment, uneontrolled ehanyes o~ the micro-
structuxes of the proteins, of lactose, or of the salts,
and microstructural reaetions of laetosP and proteins
must be prevented~
In the process aecording to the invention, milk is
first subjeeted to a moderate ultrafiltration in order to
increase the concentration of protein by a small percentage
and ef~ect a xelative decrease of the eonten-ts of lactose
and salts, In that step, the microstructures o the protein
particles which are present are made more uniform.
The polydisperse microstructure are reduced in
size toward ~onodisperse forms~ This will reduee the
stability o~the solution of protein in water~ Without
additional measures t subsequent heatiny steps would
considerably demage the proteinO For this reason, a
subsequf~nt separatiny process by whi.ch only water is
removed would have th~ result that -the protein particles
haviny a uniform, small size are uni~ormly increased in
size, the surfaee of the total protein is reduced, the
polari~y which acts outwarclly is increased and the
~L9~
ability to bind water is -thus încreasedO
As a result of the prececling ultrafiltration, all
protein particles`can be uniformly increased in size in
a succeeding evaporating step so that an approximately
monodisperse structure is obtainedJ which has a very
stable state of equilibriumO
The substances removed by the separating process
(parmeate and water) are added to the thus treatad milk in
part or en-tirely or in a larger quantit~ because the
protein particles which have been increased in size will
violently bind that liquid without an alteration of their
structure. That efEect can be assisted by a variation o~
temperature during the addition or by separate treatments
of the two phases at different temperatures.
The microstructures can be further i.mproved if,
e~g., electrodialysis processes are used tooO
In practice, the process can be carried out as
Eollows:
It is desired ~o produce 10,000 liters of milk
that h~s been subjected to an ultrahigh-temperature heat
trea~ment. The milk contains about 209 % casein, 0,6 %
protein, 4.7 % lactose and Oq7 % saltsO The total solids
content is about ~09 %l
a) Produc-tion of a Preconcentra-ta
A part of the milk, e~gO, 2000 li-ters, is
subjected to ultra:Eiltration at a temperature below 65 C
to obtain a concentrate which contains about
5.8 % casein
1 a ~ % protein
4.7 % lactose
007 % salts
11,3 % total solids
- 10
~L19079;2
The filtrate obtained con-tains about
0.2 ~ protein
4.7 ~ lactose
007 ~ salts
and is storedO
b) Preparation of 3 ~lixture
The remaining part of the milk amounting, eOg.,
-~o 8000 litars, i9 mixed with the concentrate obtained~
The resulting mixture amounting to about 9000 liters
con-tains about
3.22 ~ casein
0.64 ~ protein
4~68 ~ lactose
0~70 ~ salts
9.24 ~ total solidsO
c) Ultrafiltration o~ Mixture
The resulting mixture is then subjected once more
to ultrafiltration under the above-mentioned conditions
to obtain a concentrate which contains, e~gO, approximately
5.00 ~ casein
1.00 ~ protein
4,65 !~ lactose
0.70 '~ salts
11~35 ~ total solids.
The filtrate is also stored~ 5800 liters
concentrate and 4200 liters ~iltrate are now available~
d) ~emoval of Water
Water is then removed from the concentrate at
a temperature below 65 C by vacuum evaporation or
reverse osmoC;iS or the like until the concentrate contains
approximately
7~;2
6030 ~ casein
1026 ~ protein
5.86 % lactose
0038 % salts
14 . 30 % -total solidsO
About 4600 li~ers concentrate and 1~00 liters of a dilute
-fraction were obtained~
e) Repeated Ultrafil-tration
To promo-te a sub~equent th~rmal sterili~ation,
the concentra-te obtained in a quantity of about 4600 liters
is again subjected to ultrafiltration so that 3000 liters
concentrate are obtainecd, which contain about
9~65 ~ casein
1,94 ~0 protein
5,85 ~ lactose
0.85 ~ salts
17.69 % total solids,
and
1600 liters filtrate containing
0.2 % protein
5,9 % lactose
0.9 ~0 clalts
7~0 % t.otal solicls~
f) Backm;xinq
These 3000 liters concentrate are then mixecd with
the dilute fraction obtained by the re~oval of water~
The resulting mixture amounting ~o 4200 liters contained
- 12 ~
6.89 ~ casein
1~39 % protein
4020 ~ lactose
0~61 ~ salts
13.09 ~ total solids~
In that mixture the protein has such a microstructure
that a heat treakment will not xesult in an as-boiled taste,
in caramelizing, in Maillard reactions, and in a d~crease
of the stability of protei.nsO
The rem~;ning dispersed subs-tances were obtained
with such microstructures that -they cannot produce undesired
results in combination with protein or as independent
structures during the heat treatment~
~ s a result of the altering of the microstructures
of tha individual systems, the system can be sterili2ed
at temperatures which are much lower than those used for
an ultrahigh-temperature heat treatment~
g) Heat Treatments of Diffarent Fractions
For this reason it is proposed in accordance with
the invention that the at least two fractions obtained
in the process are separately heated at temperatures up
to ~5 C.
h) Second Backmixing
The two fractions are then mixed when they are
still hot or after they have been cooled. The resulting
end product is stable and has the original compositionO
Duri.ng the several process steps, the microstructures
are influenced as follows
a) Production of a Preconcentrate
By the pretreatment of a partial quantity by a
- 13 -
7~;~
separatirlg process consisting here o~ ultrafil~ration, -the
protein con-tent is increased and the contents of lactose
and salts remain substant.ially unchanged. This is appar~nt
upon a comparison of the composition of the staxting milk
with the composition of the preconcentrate~ As a result,
the ratio of the lactose and salt con-tents to the protein
content is decreasedO As the system was originally in a
state of an unstable equilibrium regarding the relati~e
water solubilities of the microstruckures, the product.ion
of the preconcentrate makes more water available for t:he
protein so that protein microstructures which had adapted
in size to the de~iciency of water in the starting material
can now change~
As the protein struc-tures are polydisperse in -the
starting material, the preconcentrating -treatment results
in more uniform structures having substantially uniform
properties.
b) Preparation of a Mixture
The mixing of the preconcentrate with the rpm~ining
starting material increases the quantity of water which is
available for the total protein so that the mere mixing
results in more uniform protein structures havins more
uniform proper-ties.
c) Ultrafiltration of Mix-ture
As a result of the pretrea-tment~ the cles.ired
changes in properties can be much more easily efEected by
ultrafiltra-tion. Protein microstruc-tures can now be
changes in various ways, depending on ~he nature and
direction of the ultrafiltration~
In the presen~ example the protein structures are
first reduced in siæe un-til they have all a uniform small
size~ The succaeding removal of wat~r (step d)) and the
second ultrafiltration then xesult in a u~ifoxm increase
in size ancl in a stabilization of the states oE equilibriumO
As a r~sult o., the Eirst backmixing (step f))
eflectec~ by an acldition of water having th2 properties of
a di.stillat, the protein microstructur~s ha.ve a high degree
of freedon1 of independen-t movemerlt so that a stable
e~uili~rium and a high thermal conduc~ivity are obtained~
For this reason that ~raction can be heat-treated without
det ' t-
erlora 1011.,
The second fraction (~iltrate) is substantially
f.r~e from protein and the dispersed substances contained
therein have such microstructures that the :Eraction will
~ot de-ter~orate in a ~eat traatment as there can be no
browning and no Maillard reactionO
The sterilized, stabla product ob-tained by the
second ~ackmixing has not been subjectad to an ultrahlgh-
temperature heat -treatment and for -~his reason is superior
~o to conventional sta~ilizad milk as regarc~s nutri-tion
physiology and ~lavorO
2~ Production of Cheese
Cheese .nade by conventional methods has a high
case.in content, a low protaiIl content, and ralatively low
contents of lac-~ose anc'' salts.
In -the procluction of, e~g~, curd by conventional
processæ.s, the antire system is subjact~c'. to microbial
souring~ ~if.icroorcJanisms are adcled to milk at suitable
tempera~ureC; ar.d Eerment part o:E .h2 lactose to lactic
39 ~ci~.
~ 15
A A~
Tll~ resultiny lactic acid transforms the casein
from a water-soluble s~ate to a water-insoluble stateO The
prot~ remains water~s31uble~
Suitable ~epara-tillcJ proc~ssec are then carried
out to remove a large part of the aqueous phase an~ o~ -the
subs~ances dic;sol~Te~ tller~irl~ One OL the substances clisperseA
in tlle milk~ nan1ely, casein, is recovered irl a relatively
higll concentra-tio~.
Tnat process has the ~ollowing disa~van-tages:
1. Whereas only one o~ tlle subs-tances dispersed in milk is
to be -treated and recovere~, all otller substances
dispersed in the rililk musc be proc~ssed too~
20 Whe~ proteiIls~ which are of high bioloyical value,
cannot be recover2dO
3. The process requires expensive e~uipmant and a higl
~nergy consumption because all disperssd subs-tances
must initially be processed.
~1. The process pollut~s -the environment because the whey
must be disposed of.
In view o~ these disadvantayes, therMal pretreatins
processes or additional proccsses hav~ been proposed, which
have been disclosed in Ge~rma1l Opened Applications 27 ~ 105,
25 03 840 and 25 45 847 and serve to increase the content
o~ the valuable whey proteins in the curd,
Other processes, which have been ~isclosed in
German Paten~ Publication 20 65 974 and in Britisll Pa-tent
Speci~icatior~ 9~37 and in which the protein content
o:E the sweet milk is increased by sui~table ~epara~tin~
processes, such a5 ul-tra:Eiltration or ultra:Eiltration and
washing, whereafter the milk is sou.recl and/or treatecl
- 1u ~
~g~3'7~Z
with enzylnes and a coupling product i.s not ob-tainedO
In the other processes, described in Gerr.lan Openecl
Applications 27 4~ 53S ancl 22 11 737~ sour milk or partl-y
sourecl milk is subjected to ultraEiltration or washed
with water during ul-~rafiltratisn~ The milk rnay be
evaporated be:Eore or after the ultrafiltrati.o~O
It is an ob~ect of all these processes to increase
the protein conten^t i.n relation to the collten-ts of the
othex substancPs dispersed in the milk because it is
believed that the renlainincJ dispersed contents will recluce
the quality of th2 end productO
All these processes have the disadvantage that
uncontrolled changes of the proportions are effected
reyardless of ~e changes of states of equilibri~n and without
an alte.ration of the microstructures o dispersed substances~
For ins-tance, preconcentrated milk can be used
but a spe~ific concentration has not been stated, or the
water can be removed after the ultrafilt.ration regardless
of previous drastic changes of properties of dispersed
substances~
All -these processes result in a formation of
bitter substances and in undesired jelly structures, in
poor hydrophilic properties and in a product which quickly
deteriorates in sensorial qualitiesO
It has been founcl that these undesired results
are due to -the uncontrolled chanyes of the microstructures
of the dispersecl substances rather than to the proportions
thereofO
For this reason/ known sepaxatiny processes are
used in accoxdance with the invention in o.rd~r to ef:Eect
- 17 ~
~L9~)7~;~
a con-trolled alteration of the micros~ructures of the
dispersed subscances rather than Eor a mere change of the
propor-tions oId~persed subst~ncesO
It has been found that any alteration of structure
will result also in a change in propertiesO
By the use of systen1atic~ controlled separati~g
processes in accordance with the inventionc controlled,
desirable changes in properties can be ef~ected in
accordarlce with khe invention.
It has been found. that, e~gO~ a bitter ta~te is
due to a hydrophobi~ property of dispersed substances~
For instance, an indiscriminate preconcentration
of milk by an evaporation of water be~ore ultrafiltration
will result in a de~iciency of water for all dispersed
substances, which are present in a watar-soluble form. As
a result, the structures of all dispexsed substances wil].
be altered~ For instance, casein combines with salts and
lactose~ ~ighly hydrophilic substances are bound~ The
surface area of casein is increased; the water re~uire-
ment is reduced~
When that indiscrirninate removal of water anduncontrolled alteration of structure is succeeded by an
indiscriminate ultrafiltration, water as well as lactose
and salts dissolved in said water will be removed from
the milk
Th~ remaining protein concentrate will assume
a new, uncont.rolled equilibrium owing to the presence of
an excessive quantity of water so that structures will
disintegrate in an uncontrolle~ manner and h~7drophobic
properties will become eff2ctive and will resul-t in
hydrophobic conglomera-tes so that the e~d product will
have a butter ~aste~
That undesired change in properties will be
increased iE water is added during the ultrafiltration
in order to increase the protein content relative to the
con-tents of the othe.r dispersed substances.
If an indiscriminate ultra~iltration is succeeded
by a removal of water to obtain a final concentrate having
a required solids content, the protein structure will
disintegrate as has been described he.reirlbeforeq
The previously latent hydrophobic properties are
activated and now repel waterO ~hereas a subse~uent
removal of wa~er regardless of the microstructures which
are present will result in a rebuilding o certain protein
structures, highly hydrophobic structures can no longer he
encapsulated~ The resulting products have also a strongly
bi-tter taste~
The solubility of sal~s will be improved by a
presouring or partial presouring o~ milk~ Salts which
have been combined with proteins are removed from such
compounds~ A subsequent ultrafiltration will increase the
salt content o~ the filtrate. This results in an uncontrolled
disintegration of the protein microstructures with a risk
of a development of hydrophobic properties.
An indiscriminate removal o:E water before or
after ultrafiltration resul-ts in undesired influences on
microstructures. ~e souring serves only to change the
proportions o~ dispersed substances~
Any processes which serves only to chancJe the
proportion~ oE disabled substances will inevitably result
- 19 ~
3~
in uncontrolled and uncon-trollable charlges or the structures
oE dispersed substances, i.e., in en-tirely uncontrolled
an uncontrolla~le changes of the properties o.~ the
dispersecl substancesso that a controlled end product
cannot ~e obtained in this mannerp
The i.nvenkion will now ~e explained wi~h reEerence
to the production of ~resh cheese and cheeseO It will be
pointed out that by the selective use of ]cnown separating
processes, microstructures can be in-fluenced that a
development of hydrophobic properties resulting in a
Eormation of bitter substances will be avoidedQ
A) Milk or the like, which may be provlded with any
additives that may be required~ is evaporated to remove
about 10 % water~ Very little energy is required ~or such
evapora-tion~ The protein microstructures are increased
in sizeO The structures oE the salts and of lactos~ are
so altered that they can be dissolved in less water. The
resulting structures permit a succPeding ultraEiltration
to be carried out with an optimum efficiency oE the
ultraEiltration plant becaus~ there is no danger tha-t
the altered microstructures may clog the membranesO
By the ultrafiltration, the microstructures are altered
so that the protein particles hav~ a smaller, but uniEorm
size~ For -this reason -the retentate discharged Erom the
ultraEiltration plant is immediatel~ ~vaporated once
more. As a result~ protein structures have a uni:Eorm small
size are uniformly increased in size. (The firs-t
evaporation has resulted in a noIl-uniform increase in
size of the protein structures~)
The ~rotein concentrate discharged from the
- 20 -
~9~7~2
evaporatin~ process is subjected to another ultrafiltration
process until the composition has beerl obtain~d which
corre.sponds to an optimum cheese jelly structuxe.
Compared to the state of the art, that procedure
affords the su~stantial advantaye tha-t all separating
processes are carried out in the range of optimum
efficiency, so that considerable energy can be saved~
the quantity of permeate which becomes available is
decreased by on~-hal-E or two-thirds compared with the
conventional technolo~y, and -~he sizes of the protein
structures can be SQ contxolled that a succeeding souring
or rennet process will result in a jelly which is ideal
for the type of cheese to be madeO
In a special embodiment of the process, an
ov~rconcentrati.on may be eff~cted because all separating
processes are carried out at optim~ efficiency so that
that portion of the permeate which becomes available in
such operations can be cycled and no pollutiny liquid is
to ~e disposed.of.
Any pe-rmea~e which becom~s available can be
electrodialy~ed in -that the salts of the permeate are
introduced into the concentrate before the last evaporating
stepl This practice affords th~ advantages that the ~ntire
salt content rPm~; n.~ in the cheese and that the ~uffering
capacity of the concentrate and the microstructure of
the protein can be adjusted to suit spec:ific types o~
cheeseO
Such procedures permit the preparation of par-tial
or hiyh concentrat~s for an end product consisting of soft
chees~/ cutable cheese or hard cheeseu This is not possibl~
in the state o~ the ar-ta
~ 2.1
In such processes the a.ci.d and salt contents which
arerequired in the cheese of the type desired can be
adjusted in the liquid raw product (concentrate)0
Such concentrate contains the dispersed substances
in same proportions and structures as in the finished
cheese but still in a water-soluble state~
This concentrate is then transEorme~ from a liquid
state to a semisolid or cuttable state in a single process
step, e~g./ by an enzymatic process t S that the process
steps previously requixed, which are complicated and
time-, material- and energy~consuming and pollute the
environment, are entirely eliminated.
These proc~dures accordiny to the invention can
be applied to the production o~ all milk products which
can be made. In the production of a given milk product, the
micro- and macrostructuras and the states of equilibrium
which are required in -the end product are ascertained first
and these conditions are then adjusted in the li~uid
starting raw material by separatiny pro esses carried out
in seri~s or parallel~ In the preparation of some products,
li~uids which have been separated are added during the
process or at the end of the process in an unchanged or
changed form and additional quanti-ties may alos be added
in controlled proportions if this is necessary tQ form
re~uired microstructures.
Individual fractions which become available in
the separating proc~sses and may consist of whey proteins,
lactose, salts of milk, lactic acid, water ~tc~ ~ay be
subjected to a separate treatment/ for instance, a temperature
treatment, a further æparation, a separate structure-
- 22 ~
changiny treatmen-t, etc~ and may then be processecl
separatel~ or be added to -the startillg raw material at
the same or di~erent temperatur~s~
B) 10,000 liters milk are subjected to separating
processes for alt~ring the microstructuresO The milk
contains 9~0 ~ solids and 91 % watexO
Polydisperse pro~ein struc~ures are contained
in the water.
a) First SeparatiIly Treatment
2000 liters mil]c are treated at a temperature
below 65 C fora removal of water by reverse osmosis or
evaporation until a water content of 8~ ~ and a solids
content of 12 % have been obtained~
This treatment changes the protein microstructures,
which adapt to the lower water content~ The proteins
increase in adaptation to the lower water content~
Without additional measures, -these structures would
become hydrophobic in a souring process in which substances
having a high water requir~ment (lactic acid) are formed
or addeda
b) First Dilution
For this reason the resulting concentrate ~s
diluted with additional ~000 li-ters milk~
2000 liters milk containiny l2 % solids and
88 % wat~x dilutecl at a temperature below S5 C with
2000 liters milk con-taininy 9 % solids and 91 % water~
The resulting mix-ture oE 4000 liters mil}c
contains 1005 % solids ancl ~ ~ wat~r.
The larges~ casein structures present disintegrate
to form somewhat smaller struc~ures, Casein structures of
- ~3 -
~07~12
edium and small size are not aEfected~
The smallest casein structures in the startin~
mil~ are incr~ased to an interrnediate size.
The separating and mixiny steps result in more
uniform casein structures without a developmeIIt of
hydrophobic properties.
The protein structures of ~he resultiny system
are not sufficientl~ stable in a souring process.
c) Second Separatinq Treatment
The r,lixture described above, which contains
10.5 ~ solids and 89 ~ water, is now subjected to ultra-
filtratiorl at a temperature below 65 C, preferably
60 C, until the concentrate contains more than 11 %,
preferably 13~56 % protein.
A concentra-te is obtained in an amount of 1333
liters and contains 13.56 % protein, 21 ~ total solids
and 79 % water. The permeate contains 70~ % solids and
92.d ~ water~
The removal of salt and lac-cose at the beginning
of the ultra~iltration results in a disin-t~gration of
the largest casein structures present to struc-tures OL
intermediate size~ The smallest casein structur~s which are
present ayglomerate tD form larger structuresa
It is apparent that the second separating treat-
ment xesults in still more uniform protein structures.
But owing co the shortage of wa-t~Qr, a succ~eding
souring process would still give rise to hydrophobic
properties.
d) Second Dilution
1333 liters concentra-te are diluted at a tempera-
ture below 65 C, preferably 60 C with the remaining
- ~4 -
~v~gz
6000 liters startirly rnilk~ e resulcing mixture has a
pro-tein con-LQi~c of rn.or~ ~han 5 ~0, preferably 5~25 %, a
solids conteI~t of 11.2 ~l and a water conterlt of ~8.8 %.
As a resul.t of the separatirly processes and
diluting steps carried out, the initially polydisperse
proteiIl structures have been transformed to substalltially
monodisperse structures~
ThQ su70stantiall~ monoclisperse protein structures
must be furtller stabilized. l~his is effected as follows:
e) Third Separatinq r~reatment
7333 liters of the mixture obtained in step d)
are subjectdd at 60 C to another separating process, such
as an ultrafiltration.
The resulcing conGentrate amounting to 3080 liters
contains 12.5 protein, 1~ ~ total solids and 82 % waterO
This concentrate contains stabilized, su~stantially
: monodisperse prot~in structures which even in a succeeding
microhial souring processes or after an addition of acid
will not give rise to hydrophobic properties.
The aroma can be further improved by a moderate.
: f) Third Dilution
with starting milk to a final water conten-t above 82.oo %,
preferably 82,3 %. 3080 liters concentrate cont~;ning 82
water are diluted with 500 liters sta~ting milk to obtain
a final water content of 82.28 ~0.
That final concentrate is excellently suitable
for th~ production of curd.
The protein s-~ruc-tures thu.s obtairled can ~e
further stabilized in that the Einal concentxate is
hea~ed a~ove 85 ~ and held a~ the resulting temperature
for more than 2 minutes, ~refera'oly 7 minuLLes.
- 25 -
~1~07~
Such concerltra-tes ma~ also be used for tln~
production of soft chees~, cuttabl~ chaese or hard cheeseO
In ord~r to obtain ~icrostructuxes having the
xequir~d properties in an aqueous dispersion, the ql1antity
of milk used as a ~iluent in the third dilution should
amount to at least one-half of tll~ quantity of ~he
concentrate to be diluted.
3080 liters concentrate which contain 1205 %
protein arld have a solids content of 18 % and a water
content of 82 % are dilutecl with at least 15~0 liters
milk which contains 3.4 % protein, 9 ~ total solids and
91 % water.
The resulting mixture amounts to 4620 li~ers and
contains 9 a 46 ~ protein, 15 ~ total solids and ~,5 % water.
That mixture is subjected to another separatiny
treatment ~ultrafiltration) to obtain 2300 liters of a
concentrate which contains 18.9 % protein, 24~4 ~ total
solids and 75.6 % water.
This concentrate is diluted with twice its
quanti-ty of starting milk~ 2300 liters concentrat~ +
4600 liters milk = 6900 liters of a mixture cont~;n; ng
go56 % protein, 14.13 % to-tal solids and 85087 % watera
This mixture is subjec-ted to ultrafiltra-tion at a
temperature of 55 Ca
The result.iny concentrate amounting to 2750 liters
contains 21.5 % protein, 26 5 % total solids and 73.5 %
watPr ~,
rThe properties of ~he microstructur~s o~ the
dispersed substancas of said concentrate in a water-soluble
state will not be adversely a~fected by an enzymatic
treatmen-t and by souring and salting processesO
- 26 -
~g~
The concen-trates can be mixed with cream or
crPam powder, particularly for the pro~uction of fat~y
cheese .
The properties o-f the protein structure~ can be
improved, particularly for the production of cuttable
cheese and hard cheese, if th~ last sepa.rating process is
succeaded by a removal o~ water ~o a water co~tent which
is 2-5 % lower than the legally prescribed water content.
It will be particularly desirable to e~fect before
the last separating process a modera-,e dilution with milk
and/or a protein solution and/or a whey protein solution.
The dilu~nt used may also contain fa-t.
2750 liters concentrate containing- 2105 ~ protein,
26.5 % total solids and 73~5 % water are mixed with at
least 500 liters of protein solution cont~;n; ng about 6
protelnt about 7 % total solids and 93 % water.
The resulting mixture amounts ko 3250 liters and
contains 19.12 ~ protein, 23.5 % total solids and 76.5 %
waterO Water is ~hen removed from the resulting mixture
until it has a water content of about 50 %.
From such a concen-trate in which the dispers~d
substances, particularly the proteins, have substantially
monodisperse structures, water can be removed without a
deterioration of said structures. Succeeding enzymatic
processes will be eLfected in the range of optimum
activity and will not result in a deterioration,
particularly in an activation of hydrophobic proper~ies.
I~ such concentrat~ is to be aromatized
immediately in a sweet range (pH value & to 608), eOg~,
by salting~ khe permeate which becomes available is
- 27 -
o~
subjected to electrodialysis and the r~sultins brine is
concentrated and added to the concentrateO
rrhe water-soluble microstructures thus obtain~d
can be used in a desirable process of producing~ eOg.,
cheese~
By an addition of culture concentrates or edibla
acids, the ~inal concentrate is adjuste~ to a pE value
which is rec~uired for the dcsired cheese, e~g~, 407 or
soft cheese~ 501 .Eor cuttable cheese or 504 for hard
cheese.
The protein structures which are present will not
permit a ~rmation of gel by t'nis treatment.
The required salt content of, e.g., 2 to 5 %, is
: then adjusted~ microorganism cultures and/or enzymes are
admixed, and the concen~rate, which is still liquid, is
fllled into containers.
The cheese will then coayulate and fully ripen in
the packages~
This constitutes an entirely continous process
of producing cheese.
In modifications of the process according to
the inventlon, separating processes effecting a controlled
alteration o microstructures of dispersed substances in
polydispers~ aqueous systems can be used in a controlled
manner ~o change ~he proper~ies of the disperse~ substances
in a desired manner while the dispersed substances ar~
still water-soluble~
In thi.s manner, foodstuffs of li~uid, pasty and
solid consistency can be made from poly~isperse aqueous
systems by processes which are energy-saving, economical
and friendly to the environment.
- 2~ -
~o~
3) Pro~uc~ion of Saur Milk Products
Sour milk proclucts distinguish by the nature of
-the jelly structure oE protein. ~n -their production,
protein is transformed from microstructures to macro-
structuresO Thes~ jelly structures nust be strongly
~ydropllilic~ For this purpose, their voids must be as
small as possible so that -they contain no interstitial
waterO In an idQal j~lly structure for sour milk products,
water is chemically combined or contained in capillariesO
In the process accordiny to the invention the
formation of such a jelly structure can be influenced in
that the rllilk is treated to alter the microstructure of
the dispersed substances.
Milk is Eirst evaporated~ As a result of this
removal of water~ the structures of the dispersed
substances adapt to the reduced water content. Salts are
incorporated in protein structuresO Protein particles
increase in size although the polydisperse state is
maintained, with larger particle sizes.
The ratio of ionodisperse salts and of salts
combined with proteins is changed toward thQ latter~ The
form in which lactose is dissolved in water is changed tooO
The resulting state is by no means suitable for
the formation of the jelly structure described above.
For this reason another separating process, e~g., an
ultrafiltrationl is carriecl out in accordance with the
invention~
This separating process results in more uniorm
protein scructures although this is effected in another
size range than in the previously describecl process of
- 29 -
~30~'9~
producing certifiedm11k. The resulting protein structu.res
are smaller than ihose in certified mi~k so that their
surface area is larger than in the s-tartiny milk.
Ideal conditions ar~ thus obtained for the
formation of tha above described gel structures in a
subsequent souriny processO Such ideal conditions cannot
be obtained by processes known in the art.
With the controlled microstructures obtained
according to theinvention, -the solids content can be
lower than in the starting milk so that it is possible
to add not only thep~viously separated liquid but
additional li~uid, e~g., in the form of whey or
ultrafiltrate or the likeO There will be no pollution
of the environment by coupling products.
In a special embodiment of the process~ the
permeate which becomes available is subjected to ion
exchange or eIectrodialysis and is then added to the
starting material as a buffer or as a lactose concentrate
(which may contain dissociation products of lactose)0
e) Production of Fresh Chsese
Fresh cheese has a gel structure which permits
part of the original li~uid content to be removed but
retains the remaining water~ In the prior art, water is
removed in the r~quired amount only after tha gel has
formed or water is removed from the milk by ultrafiltration,
whi.ch may bs combined with washing, and partial or hign
concentrates are produced~
T~ese processes have substantial disadvantages~
In none of these processes is -the formation of a
satisfactory jelly ensured4
- 30
In the first-mentioned process the nature of the
resulting jell~ structures and of ~he souring s~uences
cannot be controll~d~ These processes often xesult in a
~resh cheese whic~ is too dry or which loses water and
Eor this re~son has an unsatisfac-tory aroma and is not
sufficiently stabl~0
In the process involving a removal of filtrate,
possibly in combination with washing, more uniform protein
structures are obtained but this is effected in a very
unfavora~le size range so that the finished product
contains sand- or gritlike structures and bitter substancesO
These serious disadvantages are eliminated by the
process according to the invention in that the startin~
milk is treated first, e.g~, by evapoxa~ion~ The fo~Dwing
changes are effected:
Starting Milk Composition
of Milk After
Removal of Water
Water content91.00 ~ Water content88,00 %
Protein content3.40 % Protein content4~53 %
Lactose content4~70 % Lactose content6027 ~
Salt conte~t 0~8 ~ Salt content 1,18 %
Fat content 0~02 % Fat content 0~03
The protein structures have polydisperse sizes
but the protein structures are increased in ~ize~
During th~ subsequent souring processes, the
sal-t content of the milk is of essential significance
for buffering. For this reason the salt content was
adjusted so that this buffering capacity is substantially
preserved in a succeeding ultrafiltration.
- 31 -
7~
rrhe removal of wa~er is succeed~d by ultrafiltra-
tion, whi~h may xesult in a high concAntrate, although all
intermediate s-tates are possible. The high concentrate
obtainecl,~.y., by ultrafiltration, has the following
composition~
Water contenk81,27 %
proteiIl content110 25
~actose content6~27 ~
Salt content1~14 %
Fat content 0.07 %
In this process, the total solids content after
the second separating process amoun-ts to 18~73 %; -this
corresponds to the solids content of fresh cheeseO
The process according to the invention permits
the formation of jelly structures which in low concentrates
permit a controlled removal of wa-ter and in high concentrates
ensures that the souring processes will proceed in an
exactly controlled manner ancl will not permit a formation
of bitter substances or of sandy, granular structures
because the re~uirements for the formation of an optimum
jelly for fresh cheese have been met in the starting system
while the water-soluble state has been preserved~
Gelly structures having an even more exactly
predetermined consistency and buffering capacity can be
obtained in that the ultrafiltrate is sub~ected to
electrodialysis so that the salts containe~ in the ul-tra-
filtra-te are transferred into the low or high concentrates
ancl -the final product contains all salts originally
contain~d in the milk or more than the original salt
content oE the milk (i:E the ~uanti-ty of ul-traf.i.ltrate
su~jected to clialysis is incr~asecl)0
- 3~ -
7~%
This carlnot be achieved by any of the conventional
processes, in which a ma:jor part of ~he salts are removed
or even washed out.
5) El;m;n~tion of Undesired Properties in Oriyinal Poly-
disperse Ac~uaous ~ystems and Preparation of the System
for the Production of Sour Milk Products
By environmental influences, by an improper
treatment and by influences o~ the food aaten by the
animals, substances d.ispersed in original polydispersa
aqueous sys~ems may be changed in such a manner that it
is difficult or ~possible to properly manufacture a
product~
All such non-oriyinal constituents axe dissolvQd
in water and combined with oriyinal disperse~ substances
dissol~ed in waterO
For instance, certain inhibitors are known, which
in th~ production o-~ ~oods tha~ are to be soured by
microbes interfere with or entirely inhi~it the action
of microorganisms~ Such aqueous polydisper~e systems give
rise to high economic demage~
For this reason the invention as applied, for
instan~e, to systems which contain inhibi~ors proposes
tha~ the mlcrostructures of the dispersed substances
which are originally present and have ~een altered by
inhibitors should b~ influenced by separating processes
in such a manner that the effects o undesired changes in
properties will be eliminated and required properties
will be prepared at tha same time7
A portion of an inhibitor-containing milk is
- 33 -
)75~
ultrafilcer~d at a -te~ erature above ~5Q ~, particularly
~ ~ Parc of th~ liquid whic'n is discllarged, particularly
S0 % of the separated li~uid which is disclllar~ed, is
im~lediately added to tha concentrace ~ormecl in tlle second
stag~ of all ultra~iltra-ti.ori pla.nt~
'~hat operatiorl results in an al~eration of the
micrvstructur~s of casein ancl protein and a libe.ration
in-to thc aqueous phase o, inhi'~itors whicl~ Jere combined
with the original structuresO
A ldajox part oi tha now wa-ter-soluble inhibitors
contained ill the s~cond mixture are removed in th~ second
staye and are included in the permeata whic'n is discharged~
Part of the retentate obtained 'cogetll~dr witll s~arJcing millj~
that has been diluted with watex (at least 9 parts of milk
to 1 part of ~a-tar) i5 supplied to che :Lirst stage o,F t~a
ultrailtration plant and is ultra-Filtrated once more so
tha-t microstructures of dispersed milk su~stances which
a.re -Eree from inhibi-tors are continuously r~covered in the
discharged part of -the retentate and the demaged
microstructures which have not yet been traated axe
reganerated con~inuously.
As a result, the microstructures O.L the dispersed
substances cont-ained in the discharged part of the
retentate are alr~ady in a stat~ which corresponds to
original states~
Obviously such a regeneration can also b~ carried
out when the starting raw ~laterial contains other non-
origi~al water-soluble dispersed substances, e.g., from
the enviromnent~
The regenerated part is now to be ~rocessed
further to ohtain sour milk products~
~ 34 -
~19()~Y12
Sour n~ilk prodllcts ~riepencL on gel-~ormincj
properties, e~g., of dispersed milk subs-tances. It is
important that ~he ~1 is no~ Eormed in an uncontrolled
manner at ran~om i-)ut a jelly is formed which con~alns
little void water an~ much capillary water and
particularly hydrate water a
For this reason ~he w~ker-~olub]Ae micro~truc~ures
must be prepared for the aevelopment of the gel-orming
property of ~otein~ This has not be~n possible in
accordance with the state of the art.
For this reason it is proposed b~ tne invention
to dG~ e.g,, the mi`lk having microstructures which
have been corrected by the process described aboveO At
least 20 % of the milk to ~e processed is subjected to a
process by which water is removsd. 10 ~ o~ ~he water conten-t
are removed at temperatures below 65 C or preferably at
65 C
Additional 20 % of the milk to be processed are
ultrafiltered at the same time~ The ultrafiltration is
continuad until 30 % retentate and ~0 % permate have
formed. The product from which water has been removed is
then mixed with the retentate obtained by ultrafiltration.
The mixture is ultrafiltered once more at a
-temperature ofS5 C. During the ultrafiltration of the
mixture, the remainder of th~ pretreated milk at a
temp~rature of 65 C is continuously fed to -the ultra-
filtration so that the final concentrate contains at
least 1~ ~ solids~
The mllk which has thus been treated is Eree from
inhibitors and has protein microstrllctures which are
- 35 -
~ )7 ~9
water-soluble and ~ermit the iorma~ion OL an optimum
j~lly O
6~ Procassin~ of Recombine~ Systems
Recombined sys~ems are systems which have been
racovered in that substances which have been dried, for
instance, are redissolvedO
Pxocedure:
Milk powder and/or pro~ein powder of animal or
vegetable origin are mixed witll wa~er to form an aqueous
polydisperse system, Approved addit.ives, sucll as salts,
~inders, Pn~ymes, sweetening agents etc.~ which are
re~uired may be admixedO ~ecause ~he states of solution
in such a sy3tem are mainly obtained at random, it is
very difficult to process the system so as to form
produc~s~
For thisre son the invention provides that such
a random agueous system is treated to form concentrate
which ha~ contxolled microstructures and can ~e processed
~urther.
1000 liters OL a recombined starting solution are
Eirst hyparfiltexed at a temperature below 20 C, mainly
15 C, until about 10 % of the carrier li~uid have been
removed~
One-half o~ the concentra-te is then mixed with
additional 1000 liters of the recombined starting li~uid
and the mixture is ultrafiltered at 55 C until ~00 liters
concentrate hava been obtained.
Vuring the ul~rafiltra~ion, the remainder left
af-ter the hyperfiltration is continuously supplied to
the ultrafiltration,
- 36 -
0~2
" .
The concentrate which becomes available is mixed
with the carrier liquid obtained by the hyperfiltration. The
resulting concentrate can then be processed further to form,
- e.g~, evaporated or sterile milk. In this special case the
permeate discharged from the ultrafiltration step is electro-
dialyzed and the resulting liquid, which is substantially free
from salts, is admixed to the concentrate that is to be pro-
cessed further to obtain evaporated or sterile mi1k.
The product now obtained is excellently suitable ~or
making evaporated or sterile milk without an occurrence o~
Maillard reactions or a precipitation of proteins and without
' a tendency to thicken subsequently.
- 37 -
~f,,
