Note: Descriptions are shown in the official language in which they were submitted.
1075~8
- This invention relates to a method of texturizing
legume flours.
Legumes are widely used for human food and include
the following species: peas (Pisum Sativum, P. arvense), beans
(Phaseolus spp.) faba beans (Vicia faba), vetch (Vicia sativa)
lupines (Lupinus spp.), lentils (Lens esculenta), chick peas
(Cicer arietinum), cow peas (Vigna sinensis) and pigeon peas
(Cajanus spp.). Legume flours are prepared by grinding the
dried seeds which are called pulses. The major food components
of legume flours are starch and vegetable protein. Protein con-
tents of the dried seeds are normally in the range 20 to 30%.
Procedures have been developed to raise the protein content of
legume flours and, for example, yellow smooth seeded pea flours
and faba bean flours with 60% protein contents have been pre-
pared. To achieve such large protein shifts the legume flour
can be finely ground and air classified to remove a percentage
of the starches and increase protein content; or the proteins
may be preferentially solubilized and the starches removed by
filtration or centrifugation to increase protein content.
High protein legume flours are excellent sources of
vegetable protein. Potential food applications include meat
fillers and extenders, high protein snack foods, pasta, bakery
and breakfast cereal products, non-dairy beverages and infant
weaning foods. Because legume proteins are good sources of
the amino acid lysine which is the limiting amino acid in
cereals such as wheat and corn, blends of legume and cereal
proteins have P.E.R. 5Protein Efficiency Ratio) values much
higher than the P.E.R. values for cereal proteins alone. By
using legume flours, alone or in combination with conventional
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cereal flours and proteins, foods containing good to excellent
sources of high quality dietary protein can be prepared.
While legumes are an excellent source of protein they
have not been extensively used as constituents in other food
systems extensively because they compete commercially with soy
protein and they are known to be more difficult to extrude in
food making processes. They tend to stick and clump. This in~
vention relates to a very s~mple process for texturizing legume
flours that have a high pro~ein content so that they can be
used in food systems without sticking or clumping. The inven-
tion will open up vast new practical applications for high
protein pea flour that were not previously available because of
the difficulty with sticking and clumping. This invention re-
lates to a very simple process for texturizing high protein
legume flours that avoids this difficulty with these flours.
It is an object of this invention to provide a simple
inexpensive method for texturizing legume flours that does not
require the use of complex extrusion equipment.
With this and other objects in view, a method of textur-
izing a flour having a substantial starch containing legume con-
tent comprises the steps of forming the flour with a substantial
starch containing content into a pumpable aqueous slurry; said
slurry being pumpable at pressures of less than 200 pounds per
square inch; generating a source of steam; separately passing
the slurry and steam through a mixing jet and then into a cooker
wherein said slurry and steam become intimately mixed and the
flour becomes heated to at least 115C to form the flour into
a textured gel; and collecting and cooling the textured gel;
; the aqueous slurry having at least 20% protein.
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)75968
In this inv~ntion the legume flour that is to be
texturized is formed into a slurry and admixed with steam
whereby it becomes heated to texturize it. The process is con-
veniently carried out in a conventional jet cooker of the type
that is commonly used in food processing industries for steril-
ization processes and for pregelatinizing starches. The cooker
comprises two feed pipes, one for the aqueous slurry and the
other for steam; a mixing jet where the two feed streams are
brought together; a cooking chamber where the steam disburses
intimately in contact with and heats the aqueous slurry; and
an exit tube for conducting the heated slurry from the cooker
, chamber. The process is a continuous one and adjustments of
feed rates and steam pressures are made to achieve the desired
results which is usually determined by the cooking temperature
in the cooking chamber. The cooking temperature will, of
course, depend upon the rate of feed of slurry through the
cooker, the pressure of the steam that is added to the slurry
and the thermal-insulation qualities of the cooker. In a
cooker used with conventional steam pressures of 80 to 120
pounds per square inch, slurry feed pressures into the mixing
jet valve are at least as great as steam pressures and may
; well be as high as 200 pounds per square inch to achieve the
; range of cooking temperatures (115C to 185C) which are
preferable for this invention. The aqueous slurry under these
conditions is in the cooker for about between 1 to 20 seconds.
Feed pressures and cooker throughput times, however, are not
critical. They are matters of adjustment within the scope of
the invention.
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.
This invention has been practiced with a jet cooker
having 1/2 inch inside diameter stainless steel feedlines and
exit control valves and a Schutte-Koerting (Trade Mark) mixing
jet valve. The cooking chamber was nine feet long and the
aqueous slurries were mixed and pumped from a stainless steel
container with a Moyno (Trade Mark) pump. In the case of the
results that are contained in the chart which follows slurry
feed pressures of 100 to 200 p.s.i. were used and steam
pressures of about 100 p.~.i. were used. Steam and slurry
feed rates were varied to achieve the cooking temperature
range of from 116C to 163C. Following are particulars of
specific runs of slurry made from a flour particulars of which
are given in each case and the texturizing effect achieved in
each case.
TABLE I
COOR RELATIVE COOKED
EXP TEMP SLURRY CONCENTRATION CONSISTENCY OF
NO. (C) MATERIAL % SOLIDS % PROTEIN GELS (90C)
1 160 60~ pea protein 43 26 textured
2 160 60% pea protein 37 22 textured
3 160 60% pea protein 30 18 semi-textured
4 143 60~ pea protein 37 22 textured
150 50~ pea protein 40 20 textured
6 143 50% pea protein 30 15 soft
7 116 50% pea protein 30 15 soft
8 150 45~ pea protein 42 19 semi-textured
9 150 35% pea protein 42 15 soft
150 22% pea protein 42 9 very soft
11 138 61% faba bean 42 26 textured
protein
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12 160 70% soy concen- 17 12 very soft
trate
13 143 50% soy flour 26 13 soft
14 150 60% pea protein: 42 21 textured
wheat flour 4-1
150 60% pea protein: 37 22 textured
soy flour 4:1
16 150 60~ pea protein: 42 27 textured
gluten 4:1
In each of the above examples steam was flashed off
from the product as it was emitted from the exit tube of the
cooker and the temperature of the product dropped to about
90C. The cooked slurries were collected in bucket containers.
All of the cooked slurr.ies formed rigid gels upon cooling to
about 2C. However, the gels that are described as soft or
very soft at 90C settled and completely merged taking the
shape of the collecting container to form homogenious pudding
like gels. In contrast the gels described as textured gels
had fibrous structure and nonhomogenious shapes which was not
predetermined by the shape of the collecting container. In
each case the assessment of texture was based upon the cooked
consistency of the slurries just after they had left the exit
tube of the jet cooker.
Soy flour and the soy concentrate (which is not a
legume), could not be formed into a pumpable slurry with a
protein concentration as high as 20% at pressures below 200
p.s.i. At lower protein concentrations pumpable slurries
were achieved but the consistancy of the cooked soy concentrate
and soy flour slurry were very soft and soft respectively
~Tests 12 and 13). The process cannot be used to texturize
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pure soy flour. A soy flour, unlike legume flours, contains
~ very little starch and this is a factor in determination of
; the viscosity of its slurry that make it difficult to pump
at the operating pressures of this invention.
The foregoing and other tests results have shown
that texturizing of a legume flour can be achieved ~y forming
it into a pumpable slurry and passing it through a jet cooker
with steam to cook it provided that the percent protein of the
slurry is at least 20%. It has additionally been found by
other testing that sufficient cooking to achieve texturizing
of such a mixture is achieved with cooking temperatures as
low as 115C.
- A consideration of the results i~ relation to tex-
turizing of pea and faba bean protein flours shows that pro-
tein content rather than solids content of the slurry is of
importance to the development of a textured gel. Increasing
the protein content of the slurry gradually raised the gel
` strength until at the 20% protein level the gels had sub-
stantial texture upon leaving the exit tube of the jet
cooker.
The tests also show that aqueous slurries prepared
from blends of a legume such as pea flour containing up to 60%
~rotein and other flours or protein ingredients ~wheat flour,
soy flour, wheat gluten, Experiments 14, 15 and 16) which con-
tained at least a total of 2~% protein were also textured by
jet cooking. Thus, if there is in the slurry ingredients a
substantial legume flour content and a percent protein content
of at least 20% and the slurry is pumpable texturizing in ac-
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cordance with this invention will result.
While the tests relate only to pea and faba bean
legumes, the characteristics of all legumes insofar as they
are thought to be critical to thic invention are the same and
they would all be textured by the process of this invention.
The characteristic of the legume that is thought to be impor-
tant is its starch and its protein content. These things
permit the formation of a slurry that is pumpable and that
has a protein conten~ of at least 20% for use in the process.
As indicated legumes can be added to other protenatious mat-
erials which of themselves would not be texturizable with
this invention. For example, soy bean flour cannot be formed
into a pumpable slurry with a 20% protein content at pressures
of less than 200 p.s.i. and cannot, therefore, by itself be
texturized in accordance with this invention. However, a
mixture of a legume flour and a soy bean flour can be formed
into a pumpable slurry that has at least a 20% protein content
and that can be texturized in accordance with this invention.
It should also be noted that the degree of fibrous
; 20 structure to the textured gels was correlated with the protein
content of the feed slurry. For example, the textured gels
- from Experiments 1, 11 and 16 became progressively more tex-
tured.
The textured gels were cooled, oven dried and crumb-
led into small pieces.
After drying and crumbling they were evaluated for
stability in water under boiling conditions (100C) and retort
conditions (116C). The dried textured gels of this invention
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1(~759~8
,
had stabilities comparable to the stabilities of a soy protein
product prepared by the conventional method of extrusion.
Those output gels from the jet cooker described as
soft and semi-textured were also dried in an oven but after
drying they were not brittle enough to crumhle. While they
could not be crumbled they were sliced and they were sheeted
through rollers. When subjected to the stability tests in
water under boiling and retort conditions they were less stable
than the textured legume flour product and less stable than
the textured soy product texturized in the conventional manner
; by pressure extrusion.
Textured vegetable protein products including those
prepared according to this invention do tend to soften under
retort conditions. It was found that retort stabilities of the
dried textured gels prepared according to this invention could
be improved by dehydrating the gel with alcohol prior to dry-
ing. Dehydration in this way was applied to samples from
Experiments 1, 2 and 3. In each case the pretreatment im-
proved the retort stability.
; 20 It was also found that retort stability could be
improved by adding calcium ions to the slurry (1% calcium
chloride by weight of solids) into the slurry. This was
tried in the cases of several of the slurries and it was
found that it did not effect the consistancy of the textured
gel obtained from the jet cooker but that it did improve the
retort stability of the dried gel.
The dried ground gels were evaluated as meat exten-
ders in beef patties and found to be satisfactory. Meat pat-
ties, for example, were extended 30% with the dried gels
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rehydrated with two parts of water, i.e. 70 parts meat, 10
parts dried gel and 20 parts water. The patties were frozen
and then cooked by,-frying. The patties containing the dried
textured gels had excellent juiciness, firmness and chewiness
characteristics.
The dried soft gels were also used as meat extenders
and it was found that meat patties extended with these soft
not completely textured gels were softer and less chewy.
Dried crumbled textured gels made in accordance with
the invention were also used in fresh pork sausage and in
wieners at the 30% meat extension level and a 1 to 2 water
rehydration level. In both applications the extended products
had gobd texture and flavour.
The textured product of this invention has many uses
and the foregoing are only by way of example to illustrate
its efficiency and suitability. Textured legume products do
have advantages over textured soy products as additives to
other food products because they do not suffer from an objec-
tionable flavour as some other products do (soy for example)
and because of their glass-like structure they impart more
juiciness to an extended meat product than some textured
products (soy products).
It is also significant in the use of the invention
as a meat extender that it is not necessary to dry the tex-
tured gels. A textured gel from experiments such as experi-
ment No. 1 was frozen and then used as a meat extender in
patties after partial thawing. Additional moisture was added
to give 33~ solids concentration in the hydrated extender.
107596~1
Cooked patties made from such a textured product had excellent
juiciness, firmness, chewiness and flavour characteristics
comparable to those obtained in the extended patties contain-
ing the dried textured gel. Thus, frozen storage of the tex-
tured gel as it is emitted from the cooker is an alternative
to drying.
Embodiments of the invention other than the one il-
lustrated will be apparent to those skilled in the art.
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