Note: Descriptions are shown in the official language in which they were submitted.
43~7
This invention relates to a process for the production
of edible proteinic filaments of high nutritive value, and
to the proteinic filaments thus obtained.
One of the conventional methods of preparing meat sub-
stitutes based on vegetable proteins comprises forming fila-
ments from a spinning solution of alkaline pH (known as "dope"
in the English-language literature) containing the proteins,
washing the filaments thus formed and then subjecting them to
more or less complicated technological operations in the pre-
sence of various additives so as to form blocks or slabs ofwhich the characteristics are very similar to those of a piece
of meat.
Now it is known that meat is a "protein" of high nutritive
I value, whilst soya proteins, for example, are relatively medio-
'I
l 15 cre in this respect due to the lack of essential amino acids in
-, sufficient quantities, in the present case sulphur-containing
amino acids, methlonine, cysteine or cystine.
It is difficult to enhance the nutritive value of soya fi-
laments by adding the missing amino acids to the spinning so-
lution because the amino acids are only lost again when thefilaments are washed. It is equally difficult to enhance the
1 nutritive value of the end products by adding the amino acids
i to the washed filaments because these amino acids will bé lost
during the cooking process, if any. This addition can also give
rise to problems on the organoleptic level. It ls for this rea-
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son that the nutritive value is enhanced by the addition of
compounds that are less soluble in water than the amino acids.
To this end, it is possible to use spinnable proteins, such as
casein.
The present invention enables the nutritive value of fila-
ments of vegetable proteins to be enhanced at moderate cost by
utilising an abundantly available commercial by-product, namely
proteinic
whey. The present invention provides a process for producing~fi-
laments of high nutritive value, which comprises preparing an
alkaline solution containing proteins which is a mixture of (1)
proteins of vegetable origin and (2) proteins of whey and con-
taining up to 50 % by weight of proteins of whey, and passing
the solution through spinnerets into an acid coagulation bath
to form the proteinic filaments therein.
The expression "proteins of vegetable origin", hereinafter
:.
abbreviated to "vegetable proteins", applies to proteinic ex-
tracts poor in sulphur-containing amino acids, for example those
of the type which, as well known in the meat substitute indus-
try, are obtained from such plants as soya,sunflower, ground-
nuts, cow peas (Vigna sinesis), maize, horse beans and other
varieties of bean, such as broad beans (also known as Lima
beans), etc. and, generally, from leguminous plants.
I The proteins of whey are the soluble proteins of milk
which remain in the aqueous phase when the casein is coagula-
ted under the conditions normally adopted for cheese making
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or for industrially producing caseins and caseinates, and
which are therefore contained in the whey. They are known ge-
nerically by the name of "lactalbumin" which will be used here-
inafter. The lactalbumin is normally isolated by precipitation
at the isoelectric pH after thermal denaturation, or by physi- -
cal separation, in particular by ultrafiltration or gel filtra-
tion which gives a non-denatured "native" protein.
Apart from its protein content, i.e. the presence of lac-
talbumin, the alkaline starting solution or spinning solution
is an entirely conventional solution which is in the form of a
true solution, a colloidal solution or a more or less viscous
gel, depending upon the following parameters: the pH-value in
the range from 11 to 14 and preferably from 12 to 13; the con-
` centration of proteins which may amount to as much as 25 %, al-
though it is preferably from 5 to 20 %; the temperature which
is in the range from 20 to 80 C and preferably in the range
from 50 to 65 C. The alkaline agent used is normally a strong
hydroxide
base, such as sodium or potassium."The dwell time of the alka-
line solution before it passes through the spinnerets should be
as Rhort as posslble ln order to avoid excessive damage to the
proteins at these high pH-values and temperatures. Nevertheless,
it should be long enough for the solution to be homogeneous. It
, is generally from 1 to 60 minutes, depending upon the particular
i' type of apparatus used, and preferabl~ between 1 and 15 minutes.
In general, this alkaline solution also contains non-proteinic
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substances because the proteinic extracts used are generally
not 100 % pure. Thus, the vegetable extracts used contain at
least 80 % and preferably at least 90 % of proteins, whilst
the "lactalbumin" used contains from 40 to 9S % of proteins,
80 % being a satisfactory percentage.
The coagulation bath used is a bath of the conventional
type with a pH-value in the range from 0 to 4, and, better
still, in the range from 1 to 3, the acid used, obviously of
food grade, preferably being hydrochloric acid, phosphoric
acid, citric acid, acetic acid or lactic acid. As a general
rule, it also contains salts, such as sodium or calcium chlo-
ride for example.
The proteinic filaments obtained by the process according
to the invention are distinguished both by their high nutri-
tive values and also by their favourable mechanical proper-
ties. The nutritive value may be measured biologically, for
example on the scale of protein efficiency ratios (PER). The
PER is defined in the work entitled "Evaluation of Protein
Chemlstry", National Academy of Sciences and National Research
Council, No. 1100 (1963). The nutrltlve values of the fila-
ments in question are of course governed by the quantities of
lactalbumin involved, although PER-values of from 2.2 to 3.2
are readily reached as against values of at most 1.5 and, in
some cases, even negative values in the case of soya extracts
for example (depending on the treatments to which they have
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been subjected) and a value of 3.8 in the case of lactalbumin
on its own, which is one of the best proteins there is on the
nutrition level. By way of illustration, the PER values of ca-
sein and beef are of the order of 2.5 to 3. The PER of the fi-
laments increases rapidly up to a percentage content of 40 %
of lactalbumin in the spinning solution, but only minimally
thereafter so that there is no great advantage in exceeding
a proportion of the order of 50 % of lactalbumin.
Lactalbumin is known to be a protein which cannot be spun
in the absence of additives (cf. for example H.O. Jaynes and
T. Asan, J. Dairy Sci. 57 (1), 137). Accordingly, it was sur-
prising to find that mixtures of vegetable proteins in lactal-
bumin could be spun without significant difficulties, above
all when these mixtures contained a large percentage of lac-
talbumin. In addition, it was equally surprlsing to find that
,
the presence of lactalbumin did not greatly affect the mecha-
nical properties of the filaments obtained. These properties
remain more or less stable up to about 30 % of lactalbumin
coagulated at 130 C or of ultrafiltered lactalbumin. Beyond
, .
, 20 that level, the filaments obtained are not as strong as the
filaments of pure vegetable proteins, which can be an advan-
¦ tage for the preparation of certain meat substitutes. Finally,
beyond 50 % of lactalbumin, the filaments become weak, fragile
and, for example, cannot be wound onto spools. The mechanical
properties of the filaments also vary according to the nature
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of the lactalbumin. It has been found that, for an equal pro-
portion of lactalbumin, the filaments are stronger, the higher
the temperature at which the lactalbumin has been coagulated
or if the lactalbumin is an ultrafiltered lactalbumin.
Accordingly, the alkaline starting solution is a solution
containing a mixture of vegetable proteins and lactalbumin,
with a lactalbumin content of at most 50 % and preferably from
20 to 40 %.
The application of the process according to the invention
does not involve any special factors other than those which
are already well-known in the technology of spinning proteins.
One preferred embodiment of the process according to the -
invention is characterised by the use of soya protein extracts
marketed commercially by the Central Soya Company under the
trade mark Promine R, and thermally coagulated lactalbumin or,
lf appropriate, ultrafiltered lactalbumin.
The following Examples illustrate the application of the
. process according to the invention, the percentages quoted be-
` ing percent by weight.
I 20 Batch Production of Filaments
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l The following Examples relate to laboratory tests conduc-
i ted under extreme conditions. Examples 1 to 8 are intended
above all to illustrate the mechanical properties of the fila-
ments obtained; they are summarised in the following Table.
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Examples 1 to 8
885 g of an 18 % dispersion in water of proteins accord-
ing to the Table and 120 g of a 12.5 % sodium hydroxide solu-
tion are separately prepared, the dispersion and solution are
heated to 60 C and the sodium hydroxide solution is poured
slowly while stirring into the protein dispersion. This tem-
perature is maintained for 10 minutes. The liquid thus obtained
is then continuously drawn under suction into the flask of a
rotary evaporator connected to a water jet pump for deaeration.
After all the liquid has been transferred and after the tempe-
rature has fallen to the ambient temperature, the liquid, which
forms the spinning solution, is passed through a spinneret with
100 bores 100 pm in diameter immersed in a coagulation bath. At
the beginning of spinning, the total dwell time of the spinning
lS solution, including the deaeration time, is of the order of 20
to 25 minutes, and about 1 hour on completion of spinning. The
filaments obtained, with an average diameter of 97.5 ~m, are
then liberally washed with hot water (70 C~ to a pH-value of
4.5, followed by centrifuging.
The mechanlcal properties of the filaments obtained are set
out in the Table, in which the so-called "coagulated" lactalbu-
mins are lactalbumins containing 12.5 % of nitrogen (i.e. about
~0 % of proteins) coagulated by heating for 23 minutes at 100C
or for 5 seconds at 130 C and then for 20 minutes at 100 C
` 25 from a cheese-making rennet whey quality acidified to pH 4.5.
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Finally, the so-called "ultrafiltered" lactalbumin is a lac-
talbumin containing 12.5 % of nitrogen (i.e. 80 % of proteins)
obtained by the ultrafiltration on DDS 600 membranes of a
cheese-making rennet whey quality.
Example 9
Filaments are prepared under the extreme conditions of the
preceding Examples by spinning from an alkaline solution con-
taining 60 % of Promine R and 40 % of ultrafiltered lactalbu-
min. The PER of the filaments obtained is 1.38 + 0.08 as com-
pared with -0.16 + 0.08 for filaments of pure Promine R. Accor-
.,
dingly, the increase in PER amounts to 1.54.
- Continuous Production of Filaments
The following Examples relate to production tests carried
out on an industrial scale in which the alkaline treatment of
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Example 10
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'~ A 13.9 % dispersion in water of a mixture of 60 % of Pro-
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~ mine R and 40 % of lactalbumin coagulated at 130 C (cf. pre-
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~ ceding Examples) ls prepared. A 7.65 % solutlon of sodium hydro-
.,
1 20 xide is also prepared. The dispersion and the solution are
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; I pumped through a heat exchanger kept at 65 C into a Kenics
mixer, after which the liquid obtained is transferred imme-
I
diately to a vacuum deaeration tower which glves a viscous li-
: quid cooled to 25 C. This liquid is then passed through two
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spinnerets with 2500 bores 140 ~um in diameter opening into a
3 % acetic acid bath (pH 2.2). The dwell time in the alkaline
medium is approximately 5 minutes. The filaments obtained are
liberally washed with hot water to a pH-value of the order of
4.5 and then centrifuged. These filaments have a PER of 2.97
+ 0.05 as compared with 1.02 + 0.23 for pure Promine R spun
under the same conditions, and with 3.39 + 0.03 for lac~albu-
min coagulated at 100 C treated under the same conditions
(no spinning because it is not spinnable). Thus, these fila-
- 10 ments have a high nutritive value.
-~ Before preparation of the spinning solution, the PER-va-
lues of the crude mixtures were respectively:
Filaments
Promine R 1.12 + 0.17 1.02 ~ 0.13
60/40 mixture 3.09 + 0.05 2.97 + 0.05
coagulated lactalbumin 3.74 + 0.05 (3.39 + 0.03)
Accordingly, it can be seen that spinning involves only
moderate PER losses.
Examples 11 and 12
. .
The operations described in Example 10 are repeated, the
coagulation bath being a hydrochloric acid bath, with Promine
R (comparison Example) and mixtures of Promine R and ultrafil-
tered lactalbumin containing 25 % (Example 11) and 40 ~ (Exam-
ple 12) of lactalbumin.
The following results were obtained:
-- 10 --
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1064317
_ , _
ExampleBreaking load Elongation at break
g/g in %
._ ._.
Comparison 280 + 50 120 + 10
ll 326 + 20 90 + 3
63 + 18 3l + 9
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