Note: Descriptions are shown in the official language in which they were submitted.
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This invention relates to a process for the preparation
of a proteinaceous foodstuff.
For the production of various food systems oil seed
proteins are often used in the form of flours, concentrates or
isolates, which have been subjected to some treatment in order
to remove undesirable components such as off-flavours, pigments,
typsin inhibitors and flatulence factors.
The products obtained after removal of the undesirable
components are often denatured and not very useful especially
in the case where a relatively high functionality is required.
There is thus a need for a process resulting in a product
combining a high functionality with good organoleptic
properties.
We have found a process enabling a facilitated release of
pigments and off-flavour components from soy protein-containing
material.
The present invention provides a process for producing a
refined soy protein concentrate substantially free of off-
flavour components and pigments, comprising the steps of:
a) forming an aqueous slurry of defatted soy protein- ~ `
containing materia:L;
b) subjecting said slurry to alkaline conditions in the
presence of an alkali metal halide for a time
sufficient to obtain a mixture in which said pigments
and off-flavour components are substantially
completely released from said soy protein-containing
material by adjusting the pH of said slurry to a pH
of 9 to 12, and adding an amount sufficient of said
alkali metal halide such that the concentration of
said alkali metal halide in said slurry is 0.2 to 1
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Molar; and
c) separating the released pigments and off-flavour
components from the soy protein-containing material
by either apply~ng ultra-filtration to obtain a
retentate which contains the soy protein and a
filtrate containing off-flavour components and
pigments, or by precipitating the soy protein at its
isoelectric point and separating the precipitated
protein from the supernatant containing said off-
flavour components and pigments.
The starting soy vegetable protein material is defatted
prior to use, using e.g. solvent extraction. Extraction with
e.g. hexane gives excellent results. The aqueous slurry of the
starting material is easily prepared by thoroughly mixing the
defakted material with suitable amounts o~ water. The applied
ratio of solids to water can vary within wide limits but
preferably a ratio of solids to water from 1:5 to l:30 is used. -
The alkaline conditions can be obtained by using a base,
preferably an alkalimetal hydroxide such as sodium- or
potassium-hydroxide, which can be added in solid form to the
aqueous slurry or in the form of concentrated aqueous solution
in a proportion suf~icient to give a pEI ~rom 9 to 12 and
preferably ~rom 10 to 11.
The alkali metal halide is pre~erably a sodium- or
potassium halide, ideally sodium chloride is used.
The concentration of the alkali metal halide should range
from O.2 to 1 M,~preferably from 0.35 to 0.70 M.
The treatment of~the vegetable protein-containin~ material
under alkaline conditions in the presence of the alkali metal
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halide can be performed after removal of insoluble material,
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~inly consisting o~ carbohydrates or in the presence thereo~.
We have found that an effective removal of off-flavour
components and pigments is obtained if the treatment
(step a) is carried out in the absence of the insoluble
material (mainly consisting of carbohydrates), rather than
in the presence thereof, in the case where the treatment
of the starting material is followed by an ul'tra-filtration
operation (step b) which is carried out in order to
separate the released off-flavour components and pigments
from the rest of the material.,However in the case where
step (b) consists of an isoelectric precipitation it is
more advantageous to perform the treatment ~step a) in
the presence of the insoluble material.
The alkali metal halide can be added
either before or after ad~justing the pH of the aqueous
slurry of vegetable protein-containing material to the
desired value which,as already stated,lies between 9 and 12. ;'
In some instances it has been ~ound advantageous to first
raise the pH of the aqueous slurry to a pH value within '
the given range andthen to add the alXali metal halide.
The treatment under alkaline conditions in the presence of the
alkali metal halide is carried out for a sufficiently long
time to achieve a sufficient dissociation of pigments
and release of off-flavour components. A suitable method
for assessing the released amount of off-flavour components
is GL chromatography.
The duratlon of the treatment and the temperature
should be such that the treated protein remains substantially
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undenatured by which term is meant that the functionality
of the protein ~solubility, heat-setting properties, etc.)
remains practically unchanged.
Usually a treatment of less than one hour and
preferably from 1 to 15 minutes at a temperature ranging
from 20 to 40C will be adequate. -
Anyho~ the man skilled in the art will easily
find the ideal conditions in each particular case.
Separation of the undesirable components such as
off-flavour components and pigments from the rest of the
materialcanbe achieved by usirlg conventional techniques.
Preferably isoelectric precipitation or ultrafiltration
is applied. When startin~ from e.g. an aqueous slurr-y of
de~atted soy ~lakes or soymeal lsoelectric precipitation
f the protein is carried out at a pH ~rom 1l.5 to 5.5,
preferably at a pH from 4.5 to 4.8.
Dilution of the aqueous slurry prior to isoelectric
precipitation is sometimes required to facilltate the
separation of the insoluble carbohydrate and to effectively
perform the isoelectric precipitation, especially if
relatively high concentrations of the alkali metal halide
have been used.
Depending on whether the desired end-product is a protein
concentratehavingaprotein concentration of about 70% or a protein
isolate having a protein concentrati~no~ about 90%, the
isoelectric precipitation is performed in the presence or
in the absence of insoluble material mainly consisting
of carbohydrates.
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A preferred embodiment of the process according to
the invention involves:
i) forming an aqueous slurry of defatted soymeal;
ii) subjecting said slurry to alkaline condibions at a
pH from 9 to 12 in the presence o~ 0.2 M to 1 M of
an alkali metal halide to obtain a mixture i.n which
pigments and off-flavour-components are substantially
completely released;
iii) diluting said mixture with water to obtain a
mixture in which the molarity of the alkali metal .
halide is less than 0.2 M; -
iv) precipitating the protein at a pH ranging from 4.5 .
to 5.5;
v) separatin~ the insoluble mater:ial consisting of
carbohydrate~ and protein from the liquid, to
obtain a soyprotein concentrate.
Another preferred embodiment of the process
according to the invention involves:
i) forming an aqueous slurry of defatted soymeal; .
ii) subjecting said slurry to alkaline conditions at
a pH from 9 to 12 in the presence of 0~2 ~ to 1 M
of an alkali metal hal:i.de to obtain a mixture in
which pigments and off-f:Lavour components are ~ .
substantially completely released;
iii) diluting said mixture wlth water to obtain a
mixture in which the molarity of the alkali metal :
halide is less than 0.2 M;
iv) separatine the insoluble material, mainly
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DOZ~E;
consisting of carbohydrates from the ~ixture to
obbain a clarified protein solution;
v) precipitating the protein at a pH ranging from 4.5
to 5.5 from the solution to obtain a protein isolate.
According to the invention the undesirable off-flavour
components and pigments can ~ separated from the rest of the
material byusing ultra-filtration. Ultra-filtrationcan be
carried out preferably after lowering the pH of the
vegetable protein containlng mixture from the alkaline
value to a value from 6-8, by using conventional
membranes having a molecular weight cut-off limit of not
less than 1000 daltons and preferably not less than 5000
daltons. ~epending on which end-product is envisa~,e~ (protein
concentrate or protein isolate),the ultrafiltration can
be carried out in the presence or in the absence of the
insoluble carbohydrate.
A particularly preferred embodiment of the process
according to the invention for the preparation of a soy-
protein isolate involves:
i) forming an aqueous slurry of defatted soymeal;
ii) removing insoluble material,mainly consisting of
carbohydrates, from said slurry to obtain a
clarified solution; -
iii) subjecting said clarified solution to alkaline
conditions at a p~ ranging from 9 to 12 in the
presence of 0.2 M to 1 ~ of an alkali metal
halide, to obtain a mixture in which pigments
and off-flavour components are substantially
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completely released; : '
iv) lowering the pH of the mixture to a value ranging -
from 6 to 8; and
v) ultra-filtering said mixture on a membrane having :
a molecular weight cut-off limit of not less than ~.,
1000 daltons, to obtain a soyprotein isolate.
Another particularly ~referred embodiment of the
process according to the invention for the preparation
of a soyprotein isolate involves: "'
i) forming an aqueous slurry of defatted soymeal, ,
ii) subjecting said slurry to alkaline condi.tions at a ,
pH ranging from 9 to 12~ in the presence of 0.2 M ' ''
to 1 M of an alkali meta]. halide, to achleve a
substantlally complete release of pi~ments and
off-flavour components;
iii) lowering the pH of the slurry ,to a value ranging
from 6 to 8;
iv) removing insoluble material mainly consisting of
carbohydrates from said slurry to obtain a :
clarified solution,
v) ultra-filtering said clarified solutlon on a
membrane having a molecular weight cut-off limit ,''
of not less than 1000 daltons, to obtain a soy , ,
protein-isolate.
A particularly preferred embodiment of the process : .
according to the invention for the preparation of a soyprotein
concentrate involves: .'
, l) forming an aqueous slurry of defatted soymeal; ':
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ii) subJecting said slurry to alkaline conditions at a
pH ran~ing from 9 to 12, in the presence of 0.2 ~ ;
to 1 M of alkali metal halide;
iii) lowering the pH of the slurry to a value ranging
from 6 to 8;
iv) ultra-filtering the slurry on a membrane having a
molecular weight cut-off limit of not less than
1000 daltons, to obtain a protein concentrate.
The products obtained according to the invention can
be used in several food systems and particularly in those where
good functional and organoleptic performance isrequired,
like dairy desserts, simulated meat, or fish etc.
The followlng Examples illustrate the invention.
Example I
Production of a soyprotein concentrate by ultra-filtration
One part by weight of defatted soybean meal was mixed
with 10 parts by weight of water to form an aqueous slurry.
Solid sodlum chloride was added to the aqueous slurry in a
proportion sufficient to obtain o.6 M dissolved NaCl.
The pH of the mixture was raised to 10.0 using sodium
hydr-oxide. After 10 minutes the pH was lowered to 6.5 by
adding hydrochloric acid. The mixture was concentrated
two-fold in a conventional tubular module ultra-filtration
plant at 55C using a membrane cast from a solution of
, .
cellulose acetate in dimethylsu~hoxide, of a molecular
weight cut-off limit of more than 5.000 daltons. The inlet
pressure was 90 psig. and the outlet pressure 40 psig.
The concentrated slurry was diluted with an equal
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1080~2~ :
volume of water and then reconcentrated by ultra-filtration `
in order to remove the sodium chloride, water soluble
sugars, and other low-molecular weight impurities. This
washing step was repeated until atleast 90%of the low-molecular
weight impuritieshadbeenremoved. The concentrate obtained was
spray-dried to yield a white powder containing about 70% of
. protein and 30% of insoluble carbohydrate.
Example II .
Production of a soyprotein isolate by ultrafiltration
The procedure of Example I was followed except that the
insoluble material (mainly consistin~ of carbohydrates) present
in the acidified mixture (pH 6.5) was centrifuged off and the
clarified solution was ultra-filtered to yield aprotein
isolate having a protein concentration of' about ~0%.
~
Production of a soyprotein isolate by ultrafiltration
The general procedure of e~ample II was followed except
that the insoluble materi~l was removed from the aqueous
slurry bef'ore the addition of salt and sodium hydroxide
Example IV
_ duction of asoyproteln concentrateby isoelectricprecipitation
. . .
One part by welght of defatted soybean meal was mlxed
with 10 parts by weight of water. Sodium chloride was
dissolved in the aqueous extract to give a concentration
f 0.25 molar and the pH of the mixture was ad,justed to
10.0 by adding sodium hydroxide. After 10 minutes the mixture
wasdiluted with 22 volumes of water and the p~ adjusted to 4.8
by adding hydrochloric acld. The insoluble material
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consisting of precipitated protein and insoluble carbohdrate~
was centrifuged off and spray-dried.
Example V
Production of soyprotein isolate by isoelectric precipitation
The general procedure of example IV was followed except
that the pH was first lowered from 10.0 to 6.5, and the
insoluble material, mainly consisting of carbohydrate, was
removed by centrifugation before performing the isoelectric
precipitation of the protein at pH 4.8.
The precipitated protein was washed once with water
and spray-dried to yield a white bland protein powder with
a protein concentrat`lon of about 90%.
Example VI
Preparation of a proteinaceous ingredient for meat or fish
analogues
A fibrous ingredient useful for producing extended meat
or fish products or full analogues was prepared starting from
an isolate prepared according to example II.
Following the procedure outlined in US patent 3,987,213
drops of 0.05 ml of an aqueous solution containing about
25% soyprotein were added to a laminar flow of water of
9llC to coagulate the protein added. The product was collected
and used for the production of 1) a seafood analogue and 2)
a beef analogue.
Production of a seafood analogue
100 g. of the coagulated soyprotein were mixed
with 200 ml. of a flavouring composition, pH 5.8-6.2 consist- `
ing of 3% natural seafood extracts, 1.5% seafood flavours,
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0.1% salt and 95.4% water. The liquid was subsequently
drained and the drained material was mixed with a dressing
made of 94.9% mayonaise, 5% tomato ketchup and 0.1% lemon
juice.
Production of beef analogue
A mould was filled with collected soyprotein coagulates
and the material was compressed at 55O kN/m2 between paper
towelling to avoid a glossy surface on the final material.
The compressed sheet of material having a thickness
of 3 - 5 mm was soaked for a few minutes in a flavour/
texturising bath. The sheet was drained and then heat-set
in steam for 10 minutes.
When cooked in gravy and vegetables the analo~ue looked,
chewed and swallowed like a slice of beef.
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