Note: Descriptions are shown in the official language in which they were submitted.
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BACKGROUND OF THE INVENTION
Field of the Invention
This invention relates to the treatment of untextured
protein materials to form a product possessing the fibrous
texture and mouth feel properties of animal meat.
Description of the Prior Art
The food industry has spent much effort over a span
of many years and has expended large sums of money in an
attempt to utilize non-meat proteins, such as those derived
from vegetables, as additives to or substitutes for animal
meat products. It long has been recognized that the ever-
increasing worldwide food shortage could be in material part
obviated if only such relatively inexpensive materials could
be converted into products so closely approximating the
naturally occurring food material that public acceptance
would be achieved. One of the major roadblocks encountered
by-the industry has been the inability to impart the natural
and accustomed chewy, fibrous texture to vegetable protein
materials. Animal meat products inherently possess a tex-
ture giving them a definite "mount feel" which is clearlyrecognized and strongly preferred. Vegetable proteins in
their natural state generally take the form of amorphous
powders which, despite their unquestioned nutritive value,
possess mouth feel characteristics wholly unacceptable to
the consumer as a meat substitute. Moreover, vegetable
proteins normally are characterized by objectionable "beany"
flavors which the industry has been unable to remove or mask.
In recent years a number of processes and apparatus
have been developed for treating vegetable protein material
to produce a bland texturized product. None of these
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processes, however, has achieved any substantive measure
of commercial success.
The first generation of these prior art techniques
involved the wet spinning process disclosed in Boyer, U.S.
2,730,447. This process produces a fibrous product by
extruding a plurality of fine streams of an aqueous solution
of protein into a chemical coagulating bath. The protein
coagulates into fine fibers which are collected together and
treated to form an edible textured protein product. The wet
10` spinning process suffers from a number of drawbacks in addi-
tion to its general failure to produce an adequately textured
product as discussed above. The equipment employed to
perform this process is extremely sophisticated for the food
industry and represents a very high initial cost problem.
Adding further to the economic infeasibility of the product
produced by the w,et spinning process is the expensive
starting materials which must be employed. Moreover, pro-
duct uniformity is difficult to achieve due to the general
complexity of the process and the numerous parameter control
problems presented.
The second generation technique advanced in this area
is the extrusion cooking process disclosed in Atkinson,
U.S. 3,488,770, in which a protein mass is subjected to
severe physical working at an elevated temperature and there-
after extruded at an elevated temperature and pressure
through an orifice into a medium of lower professure and
temperature. This process also suffers from high equipment
costs. Moreover, the product contains objectionalbe flavor
notes in addition to the "beany" flavor originally present
in the starting materials which are apparently imparted to
the product by the processing steps. Other patents demon-
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strating the current state of the art in respect to theextrusion texturizing approach include Hale, U.S. 3,447,929;
Jenkins, U.S. 3,496,858; Anker, U.S. 3,684,522; Strommer,
U.S. 3,778,522; Lang, U.S. 3,800,053; Atkinson, U.S.
3,812,267; and Yang, U.S. 3,814,823.
The third generation of the development in the protein
texturization involves the use of steam as the texturizing
-medium. Exemplary of this approach are Strommer, U.S.
3,754,926 and 3,863,019 which treat either finely divided
protein particles or slurries with steam and Heusdens U.S.
Re. 28,091 whic~ employs a steam treatment of a protein
slurry following complex hydration steps. Products produced
by these processes also possess the general problems of poor
texture and flavor discussed above. The product is also
extremely friable.
Other attempted solutions by the art include the
cooking and shaping of a protein dough disclosed in McAnelly,
U.S. 3,142,571, and the heat coagulation of undenatured
protein disclosed in Rusoff, U.S. Re. 27,790.
Notwithstanding the veritable plethora of prior art
attempts to satisfactorily texturize vegetable proteins--no
one to date has made any really substantial progress toward
the desired goal. The present absence from the market of
any commercially accepted consumer products based on vegeta-
ble protein demonstrates clearly that the problems involved
simply have not been solved. Indeed, those meat analog
products which have found their way to the supermarket
shelves generally have been met with little or no consumer
acceptance and have generally been withdrawn. Especially
in the United States, where consumer preferences rather than
nutritional values often dictate the fate of food products,
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a successful texturized vegetable protein material simply
must possess taste and mouth feel characteristics similar
to natural meat. In addition, the prior art processes
generally have employed such complex apparatus and pro-
cedures that initial equipment and operating costs have
made protein analog products economically unattractive to
manufacturers, despite the relatively inexpensive nature of
the raw product.
Given the ever-increasing fears of worldwide famine
and the diminishing availability of animal meat protein
products, it is clear that an inexpensive, consumer-accep-
table, high protein food product based on texturized vegeta-
ble proteins is urgently needed.
BRIEF SUMMARY OF THE INVENTION
=
It is an object of an aspect of the present invention
to provide a process and apparatus for texturizing protein
which fulfills the need left by the prior art texturizing
processes.
More specifically, it is an object of an aspect of
the present invention to provide a process and apparatus
for producing discrete pieces of puffy irregularly shaped
protein material having a random fibrous texture simulating
that of natural meat.
It is an object of an aspect of the present invention
to provide a process and apparatus which will produce a bland
flavoured protein product.
An object of an aspect of the present invention is to
provide a process and apparatus which will produce a retort
stable protein product.
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It is also an object of an aspect of this invention to
provide a texturizing process and apparatus which will produce
such a product at a much lower cost due to lower initial equip-
ment costs and lower energy requirements.
It is also an object of an aspect of the present inven-
tion to provide a high quality texturized protein product from
relatively inexpensive, low protein starting materials.
In accordance with one aspect of this invention there
is provided a method for producing texturized protein in the
form of irregularly shaped pieces of puffy, randomly texturized
protein, said method comprising: a. mixing dry untextured
protein material and water to form a dough said dough contain-
ing from about 40 up to about 60% solids; b. advancing said
dough to a tubular shaped extrusion die at a temperature below
that at which texturization takes place, c. continuously
extruding said dough in the form of a hollow tubular shell of
protein material at a temperature below that at which texturi-
zation occurs; d. passing said extruded tubular shell into a
confined treating zone while simultaneously injecting a heated
gaseous stream into the interior of said shell, said gaseous
stream blowing said shell into discrete pieces of irregularly
shaped protein material and randomly texturizing said protein
material, and said gaseous s~ream further propelling said
discrete pieces of protein through said confined zone and
further texturizing said protein material, said gaseous
stream being at a pressure sufficient to perform said blowing
said shell into discrete pieces of irregularly shaped protein
material and randomly texturizing said protein material, and
being at a temperature sufficient to further texturize said
protein pieces as they are propelled through said confined
zone; e. passing said texturized protein pieces through means
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for maintaining back pressure disposed at the discharge end
of said confined treating zone; and f. recovering said text~-
rized protein pieces.
In accordance with another aspect of this invention
there is provided an apparatus for texturizing protein
material comprising: a. means for continuously extruding a
tubular shell of semi-rigid protein dough material into a
confined treating zone; b. means for injecting a heated gas-
eous stream into the interior of said extruded shell as it
enters said confined zone to blow said shell into discrete
pieces of irregularly shaped protein material; and c. means
for recovering said texturized protein material.
In accordance with another aspect of this invention
there is provided apparatus for texturizing protein material
comprising: a. means for mixing a source of protein and
water to form a protein dough; b. means communicating with
said means for mixing for advancing said dough without impart-
ing excessive work to said dough; c. means communicating
with said means for advancing for extruding said dough in the
form of continuous tubular shell of semi-rigid material; d.
means for blowing said protein shell into discrete pieces of
irregularly shaped protein material, said means for blowing
said shell into pieces comprising means for injecting a
gaseous stream into the interior of said shell as said shell
leaves said means for extruding; e. means defining a con-
fined treating zone communicating with said extrusion means
whereby said injected gaseous stream propels said pieces into
and through said confined zone; f. back pressure maintain-
ing means disposed at the discharge end of said confined
zone, said back pressure maintaining means maintaining a pre-
determined back pressure to said confined zone; and g. means
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communicating with said back pressure maintaining means
for recovering said texturized protein material.
BRIEF SUMMARY OF THE DRAWING
The Figure is a schematic drawing of the protein textu-
rizing apparatus of the present invention.
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DETAILED DESCRIPTION OF THE INVENTION
The present invention is directed to a process and
apparatus for texturizing protein material. The term
texturizing as used herein and widely understood in the art
refers to the process of changing globular amorphous
particles of protein into fibrous continuous phase protein
material with structural identity-.
The term retort stable as used herein refers to a
product which keeps its structural integrity after treatment
at elevated temperature and pressure. In the typical retort
processing test about 1 part texturized protein is mixed
with 10 parts of a 1% salt solution and sealed in a can.
The can then is placed in a retort and subjected to a temp-
erature of 250 F. and a pressure of 15 psig for about 60
minutes. The ability of a retorted product to maintain its
structural integrity and bite characteristics can be tested
by placing the product between the thumb and forefinger and
subjecting the product to shear forces. A retort stable
product will not disintegrate with moderate finger pressure.
A product with poor retort stability will feel mushy and will
fall apart when subjected to moderate shear forces.
Protein material employed in the process of the
present invention should contain at least about 40% protein
on a dry weight basis. Of primary interest are vegetable
protein materials derived from soybean. Soy proteins can
take the form of soy flour, soy concentrate, soy isolate or
mixtures thereof. The process of the present invention is
expecially well suited to texturizing low protein materials
such as soy flour. Other oilseed materials such as peanut,
cottonseed, and sesame seed may also be employed. Other
known protein materials such as those derived from wheat,
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milk, egg, single cell or leaf proteins and the like may be
texturized according to the process of the present invention.
Protein material employed should be viable, i.e., have a PDI
(Protein Dispersability Index) in the range of from about 40
to about 90%.
Other protein sources suitable for the practice of
the present invention include natural meat products. When
texturizing meat proteins, the starting material employed
should consist of a mixture of meat and a protein binder.
lQ Meat proteins may comprise meat scraps or pieces possessing
poor textural qualities such as mechanically deboned chicken,
beef, seafood, etc. or blends of the foregoing. Suitable
protein binders include vegetable proteins such as soy pro-
tein or other known proteins such as those derived from
wheat, yeast, milk, egg, etc. In general, mixtures contain-
ing up to about 80% comminuted meat may be texturized
according to the process of the present invention.
In accordance with the preferred embodiment of the
process of the present invention the protein material des-
cribed above is first mixed with water to form a proteindough or paste containing from about 40 to 60% solids. This
pasty or dough-like mixture then is advanced by an extrusion
device comprising an essentially unheated passive screw
feeding means. In this feed zone the product may be pre-
heated to a relatively low temperature in the range of about
110 to 170 F. which is below the temperature at which any
substantial texturization will take place. The screw feed
means should be of the low work type which serves mainly to
advance the protein dough rather than subjecting it to
severe physical working, and typically is operated below
100 RPM's and preferably at about 20 to 50 RPM's.
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Protein dough from the screw feed extrusion chamber
then is forced under pressure through a ring-shaped die
which produces a continuous tubular shell of semi-rigid
protein material. The term "tubular" as used throughout
the specification and claims refers to shapes other than
cylindrical tubes, such as square or triangular tubes. In
the preferred embodiment, however, the tubular extrudate
forms a right circular cylinder of protein doug. Extrusion
pressures developed at the die in the range of about 1000 to
about 1400 psi are suitable in the practice of the present
invention.
The next step of thè process of the present invention
comprises injecting a heated gaseous stream into the interior
of the tubular shell as it enters a confined treating zone
which communicates with the extrusion die.
Thè purpose of the internally injected gas stream is
to stretch the tubular protein shell in the direction of the
gas flow while simultaneously creating internal forces on the
shell which result in it being blown into discreate pieces of
irregularly shaped protein material. The gas flow serves
the further purpose of imparting a random texturizing effect
to the protein pieces as they are torn from the protein
shell. Preferably, the injection pressure and protein
material composition are chosen so that the protein shell
retains its integrity for a short distance into the confined
treating zone. In this manner the protein is held within
the environment present in the confined zone for `a period of
time, up to a minute or more, before it breaks up and is
carried out of the zone by the gas flow. This increased
holding time in the confined zone greatly enhances the
textural qualities of the product and allows a shorter
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confined zone to be employed.
In the preferred embodiment the gaseous medium is
high pressure steam. Generally, any steam pressure high
enough to blow apart the semi-ridig tubular protein shell
may be employed. In practice it has been found that pres-
sures of about 80 to 150 psi are suitable to accomplish
this result. Best results are achieved when employing
pressures in the range of from about 110 to about 120 psi.
Any manner of injection which results in an impinging
flow of steam onto the inner surface of the tubular shell
may be utilized. Preferably, the steam is injected coaxially
into the tubular shell.
After the discrete pieces of texturizing protein
break off from the semi-rigid shell, the gas stream serves
to propel the pieces through a confined treating zone. In
this confined treating zone the elevated temperàture,
pressure and turbelence of the gas flow serves to impart
further texture to the protein pieces and to volatilize
objectionable flavor compounds. Generally, temperatures in
this confined treatment zone of up to ab~ut 350 F. are
suitable to achieve texturization with best results achieved
in the range of 310 to 350 F. Pressure in the confined
treatment zone is regulated by a back pressure maintaining
means at the discharge end of the confined zone. Back
pressures of up to about 100 psi measured at the exit port,
should be maintained in the zone. Preferably, the back
pressure is kept in the ranges of 60 to 80 psi. After
passing through the back pressure maintaining means the
discrete protein particles can be recovered in any known
3Q manner.
One embodiment of the apparatus of the present
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invention now will be described by reference to the Figure.
A mixture of protein to be texturized and water is formed in
any suitable mixing means 1. The dough-like mixture from the
mixing means is discharged directly into a screw feed extru-
sion chamber 2. The screw feed extrusion chamber may be
unheated over most of its length and serves only to forward
the dough to the extrusion die. As the protein dough nears
the extrusion die some external heat may be applied by steam
jackets 3 or the like.
Communicating with the screw feed extrusion chamber
is a die assembly 4 which is effective to form a continuous
tubular shell of semi-rigid protein dough. The die assembly
of the preferred embodiment comprises two concentrically
disposed cylindrical surfaces defining an extrusion orifice.
The product produced by such a die assembly is a continuous
tube of protein material. As indicated above, the preferred
shape of the extrusion orifice defined by the die assembly
is a right circular cylinder, although other shapes may be
employed. The dimensions of the die assembly are not
critical. Preferably, the orifice thickness (i.e., the
distance between the two cylindrical surfaces of the die
assembly) should be small enough to produce an extruded
shell which can be blown apart by internal injection at
reasonable steam pressures.
As the extruded protein shell leaves the die assembly,
it passes into an area defining injection zone 5. In this
zone, a heated gaseous stream is injected into the tubular
protein shell. This preferably is accomplished by the use
of a coaxial injection nozzle 6 which delivers high pressure
steam to the inside of the shell.
Communicating with the injection zone is a confined
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treating zone 7 in which the protein material is subjected
to the action of heat and pressure from the turbulent gas
flow leaving the injection zone. Preferably, this confined
treatment zone takes the form of an elongated tube or cham-
ber. The dimensions of this tube are not critical. In
practice tube lengths of about eight to ten feet generally
provide suitable retention times although longer or shorter
tubes may be employed satisfactorily.
At the discharge end of the confined treating zone is
a back pressure maintaining means 8. This back pressure
means can comprise, for example, a spring loaded valve, a
rotary valve, or a rotary letdown pump. In general, any
device which allows the product to exit the confined zone
while maintaining a predetermined back pressure upstream
may be employed. The product issuing from the back pressure
valve may be subjected to recovery by any known means.
Since the product is essentially dry, it is only necessary
to forward the steam/protein mixture to a zone where the
steam can be vented off.
The product produced by the process of the present
invention comprises large irreguIarly shaped discrete pieces
of protein material having structural and eating properties
similar to animal meat products. This product has a fibrous
structure which is generally random in orientation. This
structure has a relatively low density and can be charac-
terized as puffy. The protein matrix has a random distribu-
tion of voids. These voids serve as shear points which give
way upon chewing to provide bite and mouth feel characteris-
tics which simulate natural meat products. Furthermore, the
product is free from objectionable flavor notes which in
themselves often made prior art products unacceptable to
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humans. Another advantage achieved by the process andapparatus of the present invention lies in the retort
stability of the product. The protein product formed in
accordance with this invention may be retorted without ther-
mal degradation of its physical or organoleptic properties.
Products produced by the process of the present
invention find utility in a number of food processing fields.
These texturized protein products may be cut into portions
suitable for direct incorporation into canned or frDzen
foods. The texturized product may also be employed as a
filler or extender in ground meat products. It is also
possible to produce fabricated nutrients from the protein
material produced according to the present invention.
The process of the present invention is also useful
to provide upgraded or restructured natural meat products.
Meat scraps or by-products with little or no food value (due
to their poor structural characteristics) can be texturized
according to the process of the present invention to provide
chicken, crabmeat, etc. cubes with good texture and mouth
feel.
The following specific examples are intended to
illustrate more fully the nature of the present invention
without acting as a limitation on its scope.
EXAMPLE 1
A textured protein material is produced in accordance
with the process of the present invention as follows. Soy
flour and water are mixed in a Hobart* bowl mixer equipped
with dough hooks to form a dough-like proteinaceous material
having a solids content of 50%. The protein dough is fed
to an extrusion texturizing apparatus as shown in the Figure.
* trade mark -13-
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The extruder is a tamale extruder originally designed
to produce a filled shell tamale type product. This tamale
extruder is modified by replacing the filling inlet mechanism
with a 1/2" steam inlet line. The die employed is tubular
in shape with a diameter of 2". The steam inlet line is
positioned concentrically inside the tubular die and the :
inlet line is provided with a plurality of holes for the
steam to escape. The die communicates with a confined
treating zone which is a 9' long tube having a 1 1/2" diame-
ter. As the extruded semi-rigid protein tube leaves the
die, it is contacted with the steam from the inlet line.
The injected steam blows the protein shell into pieces and
carries these pieces through the confined zone. At the
discharge end of the confined zone is a spring loaded back ~
pressure valve (Model # D6OR THMP Triclover Triclamp*). The
back pressure in the confined zone is about 40 to 50 psi and
the zone is maintained at a temperature of about 250 to 270
F. The resulting product consists of irregularly shaped
pieces of protein material possessing good textured quali-
ties.
EXAMPLE 2
In this example, a blend of 50% Promine* R (a soyprotein isolate having a protein content of about 95% and
produced by Central Soya, Inc.) and 50% soy flour Sprotein
content about 50%) is slurried with water to a solids
content of 45% and texturized as in Example 1. The product
exhibits a high degree of fiber development.
EXAMPLE 3
A textured protein material is produced as in Example
* trade marks -14-
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1 except that the spring loaded back pressure valve is
replaced with a back pressure rotary pump (Model C-P6 by
Creamery Package Company**). In this example, the back
pressure is maintained at about 70 psi and the temperature
in the confined zone is about 320 F. A highly textured
product is obtained from the recovery zone.
While certain specific embodiments of the invention
have been described with particularity herein, it should be
recognized that various modifications thereof will occur to
those skilled in the art. Therefore, the scope of the inven-
tion is to be limited solely by the scope of the claims
appended hereto.
** trade name
'
