U.S. patent application number 12/595042 was filed with the patent office on 2010-07-01 for functional serum protein product for use in infant food and therapeutic compositions and methods for the preparation thereof.
This patent application is currently assigned to Friesland Brands B.V.. Invention is credited to Cornelis GLAS.
Application Number | 20100168017 12/595042 |
Document ID | / |
Family ID | 38961126 |
Filed Date | 2010-07-01 |
United States Patent
Application |
20100168017 |
Kind Code |
A1 |
GLAS; Cornelis |
July 1, 2010 |
FUNCTIONAL SERUM PROTEIN PRODUCT FOR USE IN INFANT FOOD AND
THERAPEUTIC COMPOSITIONS AND METHODS FOR THE PREPARATION
THEREOF
Abstract
The invention relates to a serum protein product, suitable as an
ingredient for foods and therapeutic compositions, in particular
infant and baby foods. The invention also provides a method for the
preparation of the serum protein product, based on micro filtration
of milk. The invention provides a method for the preparation of a
serum protein product, comprising the preparation of a permeate
through micro filtration of cow's milk at a temperature of between
10 and 20.degree. C. utilizing a membrane having a pore size of
between 0.3 and 0.5 .mu.m.
Inventors: |
GLAS; Cornelis; (Tietjerk,
NL) |
Correspondence
Address: |
MORRISON & FOERSTER LLP
12531 HIGH BLUFF DRIVE, SUITE 100
SAN DIEGO
CA
92130-2040
US
|
Assignee: |
Friesland Brands B.V.
Meppel
NL
|
Family ID: |
38961126 |
Appl. No.: |
12/595042 |
Filed: |
April 16, 2008 |
PCT Filed: |
April 16, 2008 |
PCT NO: |
PCT/NL2008/050212 |
371 Date: |
March 8, 2010 |
Current U.S.
Class: |
514/1.1 ;
426/239; 426/271; 426/443; 426/491; 426/580; 426/74 |
Current CPC
Class: |
A23C 9/1422 20130101;
A61K 35/20 20130101; A23L 33/19 20160801; A61P 3/02 20180101; A23V
2002/00 20130101; A23V 2002/00 20130101; A61P 1/00 20180101; A23V
2250/5424 20130101; A23V 2200/3202 20130101; A23J 1/20 20130101;
A61P 1/14 20180101; A23L 33/40 20160801 |
Class at
Publication: |
514/12 ; 426/491;
426/271; 426/239; 426/443; 426/580; 426/74 |
International
Class: |
A61K 38/17 20060101
A61K038/17; A23J 1/20 20060101 A23J001/20; A23L 1/29 20060101
A23L001/29; A23L 1/305 20060101 A23L001/305; A23C 9/142 20060101
A23C009/142; A61K 35/20 20060101 A61K035/20; A61P 1/00 20060101
A61P001/00 |
Foreign Application Data
Date |
Code |
Application Number |
Apr 16, 2007 |
NL |
1033698 |
Claims
1. A method for the preparation of a serum protein product,
comprising microfiltering milk from a ruminant with a
microfiltration membrane having a pore size of between 0.3 and 0.5
.mu.m, at a temperature of between 10 and 20.degree. C. to obtain a
permeate.
2. A method according to claim 1, wherein the temperature is 10 to
15.degree. C.
3. A method according to claim 1, wherein the transmembrane
pressure during said microfiltering is a maximum of 2.5 bar.
4. A method according to claim 1, wherein the microfiltration
membrane is spiral-wound.
5. A method according to claim 1, wherein the pore size of the
microfiltration membrane is approximately 0.45 .mu.m.
6. A method according to claim 1, which further comprises treating
the permeate with one or more of the following processes:
ultrafiltration, nanofiltration, ion exchange, electrodialysis,
reverse osmosis, desalination, evaporation and spray-drying.
7. A serum protein product obtainable according to the method of
claim 1.
8. A serum protein product according to claim 7, containing at
least 60% of serum protein and at most 40% of casein, and wherein
the casein fraction comprises more than 75% of beta casein.
9. A serum protein product according to claim 8, containing at
least 65% of serum protein and at most 35% of casein.
10. A serum protein product according to claim 7, containing at
least 12% of casein.
11. A serum protein product according to claim 7, containing 6 to
11 grams of proline per 100 g of protein.
12. A serum protein product according to claim 7, wherein the
proline is substantially included in intact proteins.
13. A serum protein product according to claim 7, containing more
than 4.7 grams of threonine per 100 g of protein, wherein the
threonine is substantially included in intact proteins.
14. A method for the preparation of food or therapeutic
composition, comprising mixing of the serum protein product of
claim 7 with at least one additional protein, or lipid or
carbohydrate source, optionally supplemented with minerals, oligo
components and other ingredients.
15. A method according to claim 14 wherein the food is a baby or
infant food, having a serum protein to casein ratio of
approximately 60:40 based on weight.
16. A method according to claim 14, wherein, said additional
protein source is, skim milk, caseinate, acid casein or milk
protein concentrate.
17. A food or therapeutic composition obtainable according to the
method of claim 14.
18. A method to promote the maturation of the intestinal wall
and/or a proper closure of the tight junctions which comprises
administering to a subject the food or therapeutic composition of
claim 17.
19. A method to stimulate the mucus formation of the intestinal
wall and/or promoting the colonization resistance of the intestinal
flora which comprises administering to a subject the food or
therapeutic composition of claim 11.
Description
[0001] The invention relates to a serum protein product, suitable
as an ingredient for foods and therapeutic compositions, in
particular infant and baby foods. The invention further provides a
method for the preparation of the serum protein product, based on
microfiltration of milk from ruminants, and the use thereof in
foods and therapeutic compositions.
[0002] If human milk is insufficiently available, or if food with
human milk is not possible or desirable for other reasons, infant
food based on cow's milk is generally regarded as a good
alternative. Because cow's milk and human milk are significantly
different in composition, in particular protein composition,
already a great deal of research has been carried out to make the
composition of infant food approximate that of human milk as best
as possible. This process is also referred to as humanizing cow's
milk. The starting point is then that the specific composition of
human milk brings with it the desired dietary functionalities for
the child.
[0003] As for the dietary functionality of human milk, ever more
knowledge is available. A recent development in this field has
brought to light the importance of a proper availability of the
amino acid proline, via nutrition, for the intestinal wall
maturation after birth, or for prevention and treatment of undue or
undesired permeability of the intestinal wall, or for a proper
closure of the tight junctions, respectively. This is described
inter alia in NL-1023239, NL-1025900 and NL-1027262. Proline serves
as a precursor for the formation of polyamines, which are
synthesized in the body with ornithine as intermediate. In addition
to proline, also glutamate and arginine are needed for this
formation. Polyamines subsequently have the above-mentioned
positive effects on the intestinal wall. These effects are of
importance not only to children, but also to ill adults.
[0004] In addition, reference may be made to WO 01/58283, which
addresses the importance of a proper supply of glutamate and/or a
precursor for glutamate for the treatment or prevention of
hyperpermeability or undesired permeability of the intestinal wall.
WO 01/58283 also indicates the importance of the availability of
polyamines and/or precursors for polyamines, such as proline.
Further, J. Nutr. Biochem. 15, 2004, 442-451 describes that in
prematurely born children the synthesis of intestinal citrulline
and arginine is still limited, with a deficiency of polyamines as
one of the possible consequences. It follows that a proper proline
supply is also of importance to prematures.
[0005] In the infant foods of NL-1023239, NL-1025900 and NL-1027262
a sufficiently high proline level is achieved by enriching a cow's
milk protein fraction that is rich in whey proteins, with proline
in free amino acid form. Especially for infant food, however, it is
of importance that the desired composition be achieved as much as
possible on the basis of milk components, hence without adding
components foreign to milk. In addition, it is an important
endeavor to arrange not only for the amino acid composition but
also for the protein composition of the infant food to resemble
that of human milk as much as possible. This implies that proline
(and possibly other amino acids) should preferably be present in an
infant food not as free amino acid but in the form of protein.
[0006] The object of the present invention is to provide a milk
protein product that is suitable as a protein source in a food or
therapeutic composition. In particular, the object of the invention
is to provide a milk protein product allowing an infant or baby
food to be prepared which approximates the dietary functionality,
such as the amino acid and protein composition, of human milk as
closely as possible. Furthermore, the object of the invention is to
provide a method which makes the preparation of such a milk protein
product on an industrial scale attractive.
[0007] Surprisingly, it has been found that the above-mentioned
objectives can be achieved by the use of a method in which milk is
microfiltered with a membrane having a pore size of between 0.3 and
0.5 .mu.m and at a temperature of between 10 and 20.degree. C. A
milk protein product obtainable according to a method of the
present invention is formed by the microfiltration permeate, which,
as to protein composition, consists of serum proteins (>60%) and
casein proteins (<40%) and of which the casein proteins comprise
at least 75% of .beta.-casein. This concerns a proline-rich serum
protein product through the presence of the proline-rich
.beta.-casein. The proline content of the product according to the
present invention is 5 to 15 g of proline per 100 g of protein,
preferably 6 to 11 g per 100 g, and is thus comparable to the
content of human milk. This allows dispensing with the addition of
proline to infant food in free amino acid form and as a component
foreign to milk. In addition, in this way, the wish to make the
protein composition of infant food more similar to that of human
milk, is met better.
[0008] Accordingly, the invention provides a method for the
preparation of a serum protein product, comprising the preparation
of a permeate through microfiltering of cow's milk with a membrane
having a pore size of between 0.3 and 0.5 .mu.m, at a temperature
of between 10 and 20.degree. C. The use of microfiltration to
separate casein and serum proteins in milk from each other is known
per se, and so is the use of the microfiltration permeate, after
further processing, in infant food. EP-1133238 describes for
instance the recovery of serum proteins from milk through
microfiltration of milk in a conventional crossflow microfiltration
installation at a temperature of 50-55.degree. C.
[0009] Microfiltration in a method of the present invention, by
contrast, is carried out at a temperature of between 10 and
20.degree. C. It has been found that such a temperature range is
particularly suitable for the isolation of beta casein in the
permeate. Moreover, it does not require any special and/or costly
measures, such as far-reaching cooling or heating, to practice the
process on an industrial scale. Microfiltration temperatures lower
than 10.degree. C. or higher than 20.degree. C. have the drawback
of being difficult to realize on a large scale and of being
relatively expensive. In a specific aspect, microfiltration is done
at a temperature of 10 to 15.degree. C., as at 10 to 12.degree.
C.
[0010] A method according to the invention is not known from the
prior art. U.S. Pat. No. 5,169,666 discloses microfiltration of
milk at a lower temperature (2-8.degree. C.) and utilizing a
smaller pore size (0.1 or 0.2 .mu.m). WO 96/08115 concerns the
separation of serum and whey proteins from skim milk through
microfiltration and ultrafiltration. As in U.S. Pat. No. 5,169,666,
a preference is expressed for membranes having a relatively small
pore size, viz. 0.07-0.2 .mu.m. The temperature is typically
between 5 and 60.degree. C. and preferably between 10 and
50.degree. C. All Examples of WO 96/08115 concern microfiltration
at 50.degree. C. with a pore size of 0.1 or 0.2 .mu.m. WO 94/13148
describes microfiltration of raw milk utilizing a ceramic membrane
having a pore size of approximately 0.1 .mu.m at a temperature of
between 40 and 50.degree. C., in order to obtain a serum albumin
content of 10% or higher.
[0011] As starting material, milk from ruminants can be used, such
as cow's milk, goat milk, camel milk, donkey milk, buffalo milk,
sheep milk, horse milk or lama milk. Typically, cow's milk is used,
preferably the low-fat fraction of the raw milk (called skim milk).
This can be prepared according to a standard method, for instance
by centrifuging raw milk, followed by thermizing to lower the
initial germ count of the milk.
[0012] For the microfiltration, any conventional apparatus for
crossflow microfiltration can be used. Thus, for instance, use can
be made of a spiral-wound microfiltration membrane, for instance as
described in EP-A-1673975. Preferably, a process system with
multiple spiral-wound modules is used. It has been found that it is
helpful that in the crossflow microfiltration process measures are
taken for reducing the transmembrane pressure across the membrane,
in such a manner that the transmembrane pressure is 2.5 bar at a
maximum. For that reason, preferably, the transmembrane pressure
during microfiltration in a method according to the invention is
kept relatively low, that is, 2.5 bar at a maximum. Good results as
regards the protein composition of the permeate have for instance
been obtained at a maximum transmembrane pressure of 2 bars. The
average transmembrane pressure may vary, and is for instance 1.5 or
1.3 bar. In a specific embodiment, the maximum transmembrane
pressure is 1 bar, as 0.9 bar.
[0013] Instead of reducing the transmembrane pressure, a different
solution may be the use of microfiltration membranes having a
gradient in the porosity or thickness of the membrane layer.
[0014] In a method according to the invention, standard
microfiltration membranes having a pore size of between 0.3 and 0.5
.mu.m may be used. As is known in general, pore size influences the
eventual protein composition of the permeate and the retentate. In
the light of the present invention, the pore size proves to have an
influence inter alia on both the serum protein to casein ratio and
the proportion of beta casein in the casein fraction. In an
embodiment, use is made of a membrane, for instance a spiral-wound
membrane, having a pore size of between 0.3 and 0.5 .mu.m,
preferably between 0.3 and 0.45 .mu.m.
[0015] In a specific embodiment, the invention provides a method
for the preparation of a serum protein product, comprising the
preparation of a permeate through microfiltering of skim milk with
a membrane having a pore size of between 0.3 and 0.5 .mu.m, at a
temperature of between 10 and 20.degree. C., for instance
10-14.degree. C., while the transmembrane pressure during
microfiltration is 2.5 bar at a maximum, preferably 2 bar at a
maximum.
[0016] In another specific embodiment, the invention provides a
method for the preparation of a serum protein product, comprising
the preparation of a permeate through microfiltering of (cow's)
milk with a membrane having a pore size of 0.3 .mu.m, at a
temperature of between 10 and 20.degree. C., preferably
10-15.degree. C., while the transmembrane pressure during
microfiltration is 2.5 bar at a maximum, preferably 2 bar at a
maximum.
[0017] In another specific embodiment, the invention provides a
method for the preparation of a serum protein product, comprising
the preparation of a permeate through microfiltering of (cow's)
milk with a membrane having a pore size of 0.45 .mu.m, at a
temperature of between 10 and 20.degree. C., preferably
10-15.degree. C.
[0018] After carrying out the microfiltration step, the
microfiltration permeate may be further treated according to one or
more conventional processes, such as ultrafiltration,
nanofiltration, ion exchange, electrodialysis, reverse osmosis,
desalination, evaporation and spray drying. For instance, Na and K
are removed.
[0019] A further aspect of the invention concerns providing a serum
protein product obtainable according to the method of the
invention. Depending on the microfiltration conditions (for
instance pore size, temperature, transmembrane pressure), the ratio
of serum protein to casein and/or the content of proline-rich beta
casein can vary. The invention provides for instance a serum
protein product containing at least 60% of serum protein and at
most 40% of casein, and wherein the casein fraction comprises at
least 75%, preferably at least 80%, of beta casein. The serum
protein product according to the present invention finds
application in baby and infant food and therapeutic compositions.
Normally, a serum protein to casein ratio of approximately 60:40 is
contemplated in infant food to bring the protein composition in
line with human milk as best as possible. In the use of the serum
protein product according to the present invention, this can be
achieved by using, in addition to the serum protein product, a
casein source such as skim milk, caseinate, acid casein or milk
protein concentrate prepared through ultra- or microfiltration. A
specific advantage of the serum protein product according to the
invention is that the choice of the casein source is free for the
producer and hence may depend, for instance, on availability at the
respective location and time. Also in connection with this, the
serum protein product according to the present invention preferably
contains 65% of serum protein at a minimum and 35% of casein at a
maximum. The minimum content of casein may vary. Preferably, the
serum protein product contains at least 10%, more preferably at
least 12 or 15% of casein. In a specific aspect, the invention
provides a product having at least 25% of casein, for instance 28,
30, 32, 33 or 35% of casein. In view of the proline content of beta
casein, it is preferred that in particular a relatively low casein
content is coupled with a relatively high proportion of beta
casein, preferably more than 75%, as 76, 77, 78% or more.
Representative products according to the present invention
therefore contain 10-40%, 10-35%, 15-40%, 15-38% or 15-38% of
casein, of which the beta casein content is 75% or higher,
preferably higher than 75%. Utilizing a method of the invention, a
very high content of beta casein within the casein fraction can be
achieved. It provides, for instance, a serum protein concentrate
having a casein content of 5.5% and a serum protein content of
33.4% (resulting in a protein composition with 86% of serum protein
and 14% of casein), wherein the casein fraction comprises 95% of
beta casein and in addition 5% of alpha casein. Another example
concerns a serum protein product comprising 68% of serum protein
and 32% of casein, of which 79% of beta casein.
[0020] As mentioned earlier, a serum protein product according to
the invention has a number of important features as regards the
functional nutritional value. In particular, it approximates the
protein composition of human milk on different points. For
instance, the proline content of a serum protein product is between
5 and 15 grams of proline per 100 g of protein, preferably 6 to 11
grams of proline per 100 g of protein. In contrast to known
(ingredients for) (infant) foods with such contents of proline, the
proline is present not as free amino acid but, just as in human
milk, as part of a polypeptide from milk. Supplementation with
proline in the form of free amino acids is therefore not necessary.
The invention accordingly provides a serum protein product in which
the proline is substantially present as part of a polypeptide. In
this way, the wish to make the protein composition of infant food
more similar to that of human milk is met.
[0021] Another development considered of interest in the field of
humanizing cow's milk concerns the amino acid threonine. The
presence of a relatively high content of threonine in infant food
is mostly linked to the presence of glycomacropeptide (GMP), as
appears inter alia from J. Ped. Gastr. Nutr. 32, 2001, 127-130. GMP
is a cleavage product of .kappa.-casein, which is formed during
cheese-making under the influence of the enzyme chymosin.
Consequently, it occurs in sweet whey, which is often used as a
whey protein source for infant food. The oligopeptide GMP is rich
in threonine, which upon overdosing can cause hyperthreoninemia in
prematures.
[0022] There are a number of solutions known to prevent an unduly
high loading with threonine. This concerns the lowering of the
threonine content of the cow's milk products. Use of acid whey
instead of sweet whey is a known solution, as is clear from inter
alia J. Ped. Gastr. Nutr. 32, 2001, 127-130. Acid whey contains no
GMP because in the production of acid whey no enzymatic curdling of
the milk occurs. Another known solution concerns the removal of GMP
from sweet whey before using this in infant food. This is known
from EP-1048226. A third known solution concerns using, instead of
sweet whey, a serum protein product based on microfiltration
permeate of milk. This is described in EP-1133238. There, too, no
enzymatic curdling of the milk has been carried out in the
production of the respective serum protein product, which results
in a product having a relatively low content of threonine.
[0023] A serum protein product according to the present invention
usually has a threonine content of between 4.7 and 6 grams per 100
grams of protein, with the threonine, just as in human milk, being
present in intact protein molecules. Without wishing to be bound to
any theory, the present inventors propose that what is relevant for
the threonine loading of children is not so much the threonine
content as the form in which the threonine is present. It appears
from J. Dairy Sci. 75, 1992, 1380-1388 that GMP can already be
absorbed by the small intestine in intact form, that is, without
further hydrolysis. This rapid absorption of GMP possibly has
negative consequences for the synthesis of mucin in the intestine,
for which threonine is an important amino acid source. This would
argue in favor of the availability of threonine in a form less
quick to be absorbed, so that the availability of threonine in the
intestine is better. Also in human milk, threonine occurs in intact
protein molecules. The fact that threonine in a serum protein
product according to the invention is substantially present in the
form of intact protein molecules, instead of in oligopeptides or as
free amino acids, could contribute to this. The product according
to the invention contains for instance between 4.7 and 6 g of
threonine per 100 grams of protein, without involving too high a
threonine loading. The serum protein product according to the
present invention may therefore be said to involve a "slow release
threonine" content, comparable to that of human milk.
[0024] Yet another favorable nutritional property of a serum
protein product obtainable through microfiltration according to the
invention is that it contains a relatively high content of freely
available (ionic) calcium (usually circa 600-700 mg per 100 g of
protein). As a result, already upon minor heating of the product, a
maximum denaturation of especially whey proteins may be achieved.
See for instance EP-311795. The result is a product that can be
optimally employed for preventing allergy to proteins and/or a
product that has a tolerance-enhancing effect, partly owing to the
promotion of an optimum closure of the tight junctions mentioned
earlier.
[0025] A further aspect of the invention concerns a method for the
preparation of food or therapeutic composition, preferably a baby
or infant food, utilizing at least the serum protein product
according to the present invention. The method usually comprises
the standard steps of mixing at least one protein-, lipid- and
carbohydrate-source, optionally supplemented with minerals, oligo
components and other ingredients. Also, a food or therapeutic
composition, preferably a baby or infant food, is provided which is
obtainable according to such a method. In comparison with the
hitherto most current cow's milk protein sources based on whey
protein and casein, as used in the preparation of human milk
replacements, the milk proteins in a serum protein product
according to the invention are not, or hardly so, associated. This
provides the advantage, among others, that on the basis of this
protein source in combination with the usual fats, a highly stable
and fine emulsion can be formed. With this, the digestion of the
end product can be improved, and/or the occurrence of digestive
disorders be prevented.
[0026] In the (baby and infant) food and therapeutic compositions
according to the present invention, it is also possible that, in
addition to the serum protein product, they contain other proteins
such as whey proteins, .alpha.-lactalbumin, lactoferrin and
vegetable proteins, as from soybean or wheat. In an embodiment, the
method concerns the preparation of a baby or infant food,
preferably with a serum protein to casein ratio of approximately
60:40 by weight. Eligible for use as an additional protein source
are skim milk, caseinate, acid casein or milk protein concentrate.
Moreover, both the serum protein product and other proteins can
have undergone a hydrolysis step. This is for instance conventional
for preventing allergies whereby protein is hydrolyzed under the
influence of pancreas enzymes.
[0027] It is further conventional to add to baby and infant food
and therapeutic compositions carbohydrates, such as lactose and
oligosaccharides, lipids and ingredients such as vitamins, amino
acids, minerals, taurine, carnitine, nucleotides and polyamines,
and antioxidants such as BHT, ascorbyl palmitate, vitamin E,
.alpha.- and .beta.-carotene, lutein, zeaxanthin, lycopene and
lecithin. The lipids are mostly of vegetable origin. In addition,
the food or the therapeutic composition may be enriched with
polyunsaturated fatty acids, such as gamma-linolenic acid,
dihomo-gamma-linolenic acid, arachidonic acid, stearidonic acid,
eicosapentaenoic acid, docosahexaenoic acid and docosapentaenoic
acid. With a view to a proper development of the intestinal flora,
probiotics may be added, such as lactobacilli and/or
bifidobacteria, as well as prebiotics. A preferred combination of
probiotics is for instance Bifidobacterium lactis with L. casei, L.
paracasei, L. salivarius or L. neuter. Examples of prebiotics
include fuco-, fructo- and/or galacto-oligosaccharides, both short-
and long-chain, (fuco)sialyloligosaccharides, branched
(oligo)saccharides, sialic acid-rich milk products or derivatives
thereof, inulin, carob bean flour, gums, which may or may not be
hydrolyzed, fibers, protein hydrolysates, nucleotides, etc.
[0028] A food or therapeutic composition according to the invention
can be advantageously used to promote the maturation of the
intestinal wall and/or a proper closure of the tight junctions. It
has also been found that it can stimulate the mucus formation of
the intestinal wall and/or promote the colonization resistance of
the intestinal flora. The invention thus provides a
resistance-enhancing protein concentrate. Without wishing to be
bound to any theory, the present inventors propose that while
threonine is an important amino acid source for an optimum
synthesis of mucin, it is in particular the peptides resulting from
enzymatic digestion of beta casein that promote mucus secretion.
This means that a serum protein product enriched in beta casein
according to the invention with a threonine content of 4.7-6 g/100
g not only does not have any disadvantages (since it is present as
"slow release threonine") but also can contribute to an optimum
mucus formation at the level of the intestinal wall. This can
involve both the induction and the preservation of mucus formation.
A serum protein product according to the invention can therefore,
through stimulated mucus formation, have a favorable influence on
the build-up of resistance to pathogens.
[0029] What is more, it has been found that a serum protein product
according to the invention has a specifically favorable effect on
the intestinal flora in comparison with traditionally applied whey
proteins from sweet whey. For more details, see Example 4
below.
[0030] The invention will now be illustrated in and by the
following Examples.
EXAMPLE 1
Comparative Example
[0031] Skim milk was prepared by centrifuging raw milk and then
thermizing the skim milk for 15 s at 67.degree. C. This skim milk
was microfiltered in a process system with 1 spiral-wound module
(DSS, pore size 0.15 tin, membrane surface 14 m.sup.2), at a
temperature of 10.degree. C. and a maximum transmembrane pressure
of 1.8 bar (on average 1.3 bar). The skim milk was filtered
batchwise to a volume reduction factor (VRF) of 3.3. The permeate
was then concentrated by means of ultrafiltration (UF) and dried to
a powdery serum protein concentrate. The casein content of the
serum protein concentrate was 5.5% and the serum protein content
was 33.4%, resulting in a protein composition with 86% of serum
protein and 14% of casein. The casein fraction was comprised of 95%
of .beta.-casein and in addition 5% of .alpha.-casein.
[0032] The serum protein fraction comprised 24% of .alpha.-la and
75% of .beta.-lg. The amino acid composition is represented in
Table 1.
TABLE-US-00001 TABLE 1 Amino acid Content (g/100 g of crude
protein) Arginine 2.5 Cysteine 2.9 Histidine 2.3 Isoleucine 5.7
Leucine 12.9 Lysine 9.9 Methionine 2.2 Phenylalanine 4.0 Threonine
5.2 Tryptophan 2.4 Tyrosine 3.3 Valine 5.8 Aspartic acid 12.3
Glutamic acid 19.5 Serine 4.8 Proline 5.6 Glycine 2.1 Alanine
4.2
EXAMPLE 2
[0033] Skim milk was prepared by centrifuging raw milk and then
thermizing the skim milk for 15 s at 76.degree. C. This skim milk
was microfiltered in a process system with four spiral-wound
modules (DSS, pore size 0.45 .mu.m, membrane surface 56 m.sup.2),
at a temperature of 10.degree. C. and a maximum transmembrane
pressure of 2.5 bar (on average 1.5 bar). The skim milk was
filtered to a VRF of 3.3 in a continuous process mode. The permeate
was then concentrated by means of UF and dried, so that a powdery
serum protein concentrate was obtained. The casein content of the
serum protein concentrate was 15.9% and the serum protein content
was 33.4%, resulting in a protein fraction with 68% of serum
protein and 32% of casein. The casein fraction was comprised of 79%
of .beta.-casein and in addition 18% of .alpha.-casein and 3% of
.kappa.- and .gamma.-casein. The serum protein fraction comprised
25% of .alpha.-la and 73% of .beta.-lg and 1% of BSA. The amino
acid composition is represented in Table 2.
TABLE-US-00002 TABLE 2 Amino acid Content (g/100 g of crude
protein) Arginine 2.4 Cysteine 2.3 Histidine 2.1 Isoleucine 4.8
Leucine 11.8 Lysine 9.1 Methionine 2.1 Phenylalanine 4.0 Threonine
4.8 Tryptophan 2.0 Tyrosine 3.5 Valine 5.2 Aspartic acid 10.6
Glutamic acid 18.0 Serine 4.9 Proline 6.4 Glycine 2.0 Alanine
4.1
EXAMPLE 3
[0034] Prepared was a food for infants, which was composed as
specified in Table 3 below, starting from the serum protein
concentrate of Example 1. The serum protein concentrate contained
5.6% of proline and 5.2% of threonine and the Na caseinate 10.5% of
proline and 4.9% of threonine, expressed as a percentage of the
total crude protein.
TABLE-US-00003 TABLE 3 Component per 100 g Proteins g 10.7 Serum
protein concentrate g 7.1 casein g 3.6 Proline (% of crude protein)
% 7.1 Threonine (% of crude protein) % 5.1 Fat g 27 Linoleic acid g
3.3 .alpha.-Linolenic acid g 0.47 DHA mg 53 AA mg 53 Carbohydrates
g 55 Lactose g 53 Maltodextrin g 2 Dietary fiber g 1.8
Galacto-oligosaccharides g 1.8 Minerals, Vitamins Nucleotides g
1.9
EXAMPLE 4
[0035] This Example illustrates the favorable effect on the
intestinal flora of a serum protein product according to the
invention (herein called SPC) in comparison with DEMINAL90, a
conventional whey protein product based on sweet whey.
[0036] A serum protein product obtainable according to a method of
the invention utilizing a 0.45 .mu.m membrane and DEMINAL90 were
incorporated into media that served as nutrient source in
pH-controlled batch cultures (BATCH 2 and BATCH 3, respectively).
In addition, the two products were incorporated in two separate
media after being treated with proteases. These media were also
used as nutrient source in pH-controlled batch cultures (BATCH 4
and BATCH 5, respectively). The proteases had been so selected and
so incubated with the protein products as to simulate the
conditions in the gastrointestinal part of the human body as best
as possible, that is, pepsin treatment at pH 3.0 and a treatment
with a pancreas extract at pH 6.5. The medium contained yeast
extract, NaHCO.sub.3, KH.sub.2PO.sub.4, K.sub.2HPO.sub.4, NaCl,
cysteine.HCl, MgSO.sub.4, CaCl.sub.2, hemin, Resazurin, Tween-80
and vitamin K.
[0037] The sterile, pH-controlled batch culture with medium was
made anaerobic and inoculated with freshly obtained baby feces of a
healthy child, the feces having been incorporated in a slurry based
on PBS. The different protein sources were added to the batch
cultures. Also, a reference culture with a minimal amount of
protein and without additional test protein sources (BATCH 1) was
prepared which was also inoculated with feces slurry.
[0038] The batch culture was incubated for 6 hours at a temperature
of 37.degree. C., after which samples were taken which were
analyzed for the presence of microbial organisms. The analysis was
carried out by means of DNA amplification and a DNA hybridization
assay. The assay was set up and validated for detection and
quantification of both Bifidobacterium genera, Lactobacillus genera
and other bacterial species, such as Escherichia coli, Clostridium
difficile, Salmonella, Bifidobacterium longum, Lactobacillus casei.
The hybridization was carried out with fluorescent probes specific
to the bacterial species. Specifically bound probes were quantified
with a dedicated scanner. The measured fluorescence signal was
correlated with the amounts of bacteria by means of software. The
signals were corrected for the background signal obtained from
BATCH 1.
[0039] The corrected signals of the tested batches that correspond
to Bifidobacteria are shown in FIG. 1. The following codes were
used: [0040] DD=digested DEMINAL90 [0041] DS=digested serum protein
product of the invention [0042] UD=undigested DEMINAL90 [0043]
US=undigested serum protein product of the invention
[0044] The y-axis plots the number of bacteria in arbitrary units
that correspond to the fluorescence measured after hybridization
and standardization for each bacterial species.
[0045] The FIGURE shows the stimulating effect of a digested serum
protein product according to the invention in comparison with a
conventional whey protein preparation. The expectation is that this
favorable effect can be ascribed at least for a part to the
presence of beta casein.
EXAMPLE 5
[0046] This Example describes four different examples (A, B, C and
D) of a method according to the invention for the preparation of a
serum protein isolate.
[0047] A) Skim milk was prepared by centrifuging raw milk and then
thermizing the skim milk for 15 s at 67.degree. C. This skim milk
was microfiltered in a process system with two spiral-wound modules
(Parker, pore size 0.3 .mu.M, membrane surface 28 m.sup.2), at a
temperature of 15.degree. C. and a maximum transmembrane pressure
of 0.9 bar (on average 0.6 bar). The skim milk was filtered to a
VRF of 4.0 in a continuous process mode. The casein content of the
serum protein isolate was 0.8% based on total dry matter and the
serum protein content was 6.7% of serum protein based on total dry
matter, resulting in a protein fraction with 89% of serum protein
and 11% of casein.
[0048] B) Skim milk was prepared by centrifuging raw milk and then
thermizing the skim milk for 15 s at 67.degree. C. This skim milk
was microfiltered in a process system with two spiral-wound modules
(Parker, pore size 0.3 .mu.m, membrane surface 28 m.sup.2), at a
temperature of 10.degree. C. and a maximum transmembrane pressure
of 0.9 bar (on average 0.6 bar). The skim milk was filtered to a
VRF of 4.0 in a continuous process mode. The casein content of the
serum protein isolate was 1.3% based on total dry matter and the
serum protein content was 7.3% of serum protein based on total dry
matter, resulting in a protein fraction with 85% of serum protein
and 15% of casein.
[0049] C) Skim milk was prepared by centrifuging raw milk and then
thermizing the skim milk for 15 s at 67.degree. C. This skim milk
was microfiltered in a process system with two spiral-wound modules
(DSS, pore size 0.45 .mu.M, membrane surface 28 m.sup.2), at a
temperature of 10.degree. C. and a maximum transmembrane pressure
of 0.9 bar (on average 0.6 bar). The skim milk was filtrated to a
VRF of 2.0 in a continuous process mode. The casein content of the
serum protein isolate was 2.6% based on total dry matter and the
serum protein content was 6.3% serum protein based on total dry
matter, resulting in a protein fraction with 70% of serum protein
and 30% of casein.
[0050] D) Skim milk was prepared by centrifuging raw milk and then
thermizing the skim milk for 15 s at 67.degree. C. This skim milk
was microfiltered in a process system with two spiral-wound modules
(DSS, pore size 0.45 .mu.m, membrane surface 28 m.sup.2), at a
temperature of 10.degree. C. and a maximum transmembrane pressure
of 2.5 bar (on average 1.5 bar). The skim milk was filtrated to a
VRF of 2.0 in a continuous process mode. The casein content of the
serum protein isolate was 1.5% based on total dry matter and the
serum protein content was 3.0% of serum protein based on total dry
matter, resulting in a protein fraction with 67% of serum protein
and 33% of casein.
* * * * *