Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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~L~72392
This invention relates to textured proteins. More
specifically, the present invention provides a new process for
preparin~ fibrous protein materials which can be used as, or in
the production of, meat analogs.
In recent years, considerable research eforts have
been focused upon developing new technology for producing meat-
like, protein-containing foods from various vegetable and animal
protein sources. ~conomics provides a major incentive. It would
clearly be advantageous to substitute, at least in part, the more
efficient process of growing vegetable protein for the rather
inefficient process by which animals convert the proteinaceous
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vegetable materials into meat. This is especially true where the
ever-increasing human population is feared to be out-distancing
the availability of grazing land for meat-producing animals.
Additionally, recent efforts have also been directed to avoiding
certain natural products which may be undesirable for religious,
ethnic, or health reasons.
All natural meats, including fish and poultry, have
fibrous structures. The texture of the meat products is inherently
dependent upon the fibrous nature of the meat. Likewise, the
presence of a fibrous structure is an important factor in fabri-
cated meat-like products. Thus, in producing these meat-like
; products, e.g. meat analogs, much effort has been directed to
creating a fibrous structure, similar to natural m~at. ~any
workers have developed a wide variety of techniques for obtain-
ing fibrocity, and a good deal of published literature is avail-
able on the production o~ meat analogs with fibrous structures.
One early worker, Boyer, in U.S. Pa-tent ~,682,466
discloses the formation of synthetic meat products containin~
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quantities of vegetable protein filaments. These protein
filaments are made by forcing a colloidal protein dispersion
through a porous membrane, such as a spinnerette, into a coagu~
lating bath causing precipitation of the protein in filament form.
The filaments are assembled into a meat-like product by employing
binding materials, including cereals and protein. The use o~
spun vegetable fibers enables the formation of a highly aligned
fibrous structure. Unfortunately, the manufacture of spun fibers
is complicated and relatively high in cost. Moreover, spun
vegetable protein is generally poor nutritionall~ because the
starting material depends on soy isolateO
In view of the difficulties inherent in spun fiber
technology, other workers were encouraged to seek alternatives to
this technique. One alternative, disclosed in U.S. Patent
No. 3,488,770, describes the production of a proteinaceous meat-
like product having an open celled structure with cell length
greater than cell width, and with the cells being substantially
aligned. This product is made by extruding a dough, substantially
free of non-proteinaceous filler, into an area of reduced pressure
to cause expansion. Another alternative process working with a
dough is disclosed in U.S. Patent 3,693,533. ~ccording to that
process, the protein containing dough is coagulated while being
passed through a set of converging conveyors. The resulting
stretching during coagulation produces what are described as uni-
directional fibers. While these processes are potentially less
costly than the spun fiber technology, they suffer a penalty in
the quality of the fibers produced.
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- Several workers, in published Japanese Specifications
48-21,502 and 48-34,228, and United States Patents 3,870,808 and
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3,920,853 describe the production of fibrous protein masses by
processing including freezing a protein solution or dispersion
- and heating the frozen mass to heat set the protein. These
fibrous products are described as being meat-like and can be
further improved by a freeze-drying step prior to heat setting.
This invention, in its broad aspects, comprises
freezing an aqueous~mixture of heat coagulable protein by cool-
; ing in a manner and at a rate effective to create elongated ice
crystals generally aligned perpendicular to the surface of
cooling, and immersing the resulting frozen mass in an aqueous
solution, comprising an edible, water-soluble material capable
of lowering the freezing point of water and stabilizing the
protein for a time effective to stabilize the protein in the
frozen mass. Aqueous ethanol is a preferred solution.
- According to the present invention, a wide variety of
meat-like textures can be simulated using a wide variety of
~; protein materials. The common characteristic of all of these
products is the presence of weIl-defined, well-ordered fibers.
The fibers are produced by the present method from protein of
vegetable or animal origin---used separately or in combination.
In this manner it is possible to easily balance the textural,
taste and nutritional characteristics of the fibers to provide a
- textured protein material having the desired characteristics.
Among the features important to the present invention are the need
for cooling in a direction and at a rate effective to produce the
weIl-defined, well-ordered ice crystals, and the need to stabilize
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the protein by immersing the frozen mass into a stabilizing solu-
` tion to assure retention of the fibrous structure defined by the
ice crystals.
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Any edible protein, or combination of proteins, can be
employed in the process of the present invention, providing that
the sole protein or, in the case of combinations, at least one of
the proteins is soluble or partially soluble and can be stabilized
by treatment according to this invention. In general, proteins
having excellent solubility provide excellent, distinct fibrous
structures---probably because the ice crystals can grow freely,
unrestricted by undissolved solids. ~owever, protein solutions
containing considerable insoluble material, such as soy flour,
meat homogenates, and fish homogenates, can also be employed with
good results to form fibrous structures according to the present
invention. Representative of the protein materials which can be
employed to give excellent results according to the present
process are soy milk, soy isolates, whole milk, meat slurriesr
fish slurries, gluten, soy flour, wheat protein concentrate, milk
whey, egg protein, blood protein, single cell protein and the
like.
The final texture of the products depends in part on
the protein source employed, as well as the additives such as
flavoring, fillers, fat, carbohydrates, salts, and the like. For
example, the products prepared from soy milk have a juicy, smooth,
soft texture with good fiber tensile strength. The soy milk
produces a product having a smoothness and softness resembling
raw chicken meat, probably due to the oil emulsified in the
protein. Soy flour, on the other hand, gives a product with
lower tensile strength than the soy milk, but this type of
tenderness is desired in some products either alone or as a
component with another protein material.
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The protein, from whatever source, is admixed with
water to form an aqueous protein mixture wherein at least a
portion of the protein is dissolved in the water. The aqueous
protein mixture can be characterized as a solution, dispersion
or suspension of protein and water. To increase the degree of
solubility of the protein, which varies for different types of
protein, the pH of the mixture can be adjusted. To obtain the
optimum tensile strength and fiber integrity it is usually
desirable to adjust the pH of the aqueous protèin mixture to the
point of maximum protein solubility. The pH of the mixture
appears to directly affect the tensile strength of the final
textured product. Some protein materials such as soy flour, give
better texture and tensile strength at high pH, e.g. pH 10, than
at lower pH. This is probably because these proteins are more
soluble at higher pH, and are partially dissociated and de-
natured by the alkaline conditions before texturization. At high
pH, the protein molecules tend to unfold, allowing more complete
dissociation and apparently allowing more freedom of movement
during freezing to form more perfect fibers. Some proteins, such
as egg white have good solubility at their natural pH and need
not have their pH adjusted to alkaline conditions.
While h~gh pH is sometimes useful in preparing the
textured product, excessively high pH values may not be desirable
in a meat analog product. The pH of the ~inal product can be
reduced during rehydration, to be later explained in detail, by
the use of an acid in the rehydration bath. At times, however,
reducing the pH of the textured product to a level below the
point at which the particular protein is immobilized, may a~fect
the texture of the product. Depending on the particular end use
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contemplated, this textural effect may be desirable or undesirable.
; For the proteins which are solubilized at their natural pH of 6
to 8, no neutralization will be needed.
The aqueous protein mixture is easily obtained by
mixing the protein in water. If necessary, the protein material
can be fineIy divided or comminuted either before or after mixing
with the water; and, the pH can be adjusted to obtain the optimum
solubility. The presence of soluble and insoluble non-coagulating
materials is acceptable, and indeed in some cases desirable so
long as it does not adversely affect the desirable qualities of
the fiber structure for a particular application. In some
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cases, the presence of excessive amounts of fat would be un-
desirable where it would reduce the tensile properties of the
fibers.- However, in other cases, a reduced tensile strength
would be desirable as it would impart a more tender texture to
the product. Thus, those additives normally employed in forming
fibrous meat analog products can be employed according to the
present invention, it being realized that the process of the
present invention provides a process capable of widely modifying
the compositional features of the fiber forming material to obtain
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a wide variety of textural and nutritional variations from the
single basic process. It is an added advantage of the present
invention that relatively high fat contents can be employed and a
good fibQr structure obtained.
` The solids concentration of the mixture can affect
both product texture and processing efficiency. It is generally
desirable to maintain low solids concentrations. One reason is
that there is a tendency to diminish distinct fibrous structure
by increasing the concentration of solids. Typically, the solid
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content will not exceed about 40%, and preferably not more than
about 35% of the mixture on a weight basis. When the solids
concentration increases, the time required for imm-ersion in the
stabilizing solution is increased. However, processing at
excessively low concentrations loses economy due to the increased
costs of removing the water. The costs for eneryy, vessels,
transfer and storage equipment increase rapidly as concentration
is reduced. However, the quality of the fibers produced at low
concentrations is high. It is therefore necessary to determine
the optimum concentration for ea`ch particular system, under-
standing that there are many influences which must be considered.
~ In a very broad sense it can be said that the optimum concentra-
; tion for freezing will be anywhere from 3% to about 35% protein,
with concentrations of from 10~ to 30% being preferred, based
upon the total weight of the aqueous protein mixture. It is
clear however that the optima for particular protein and addi-
tive materials, may vary widely within this range and at times
extend beyond this range.
Those skilled in the art will be able to determine the
optima for the particular systems employed especiall~ with the
knowledge of the economics of their particular processing equip-
ment and procedures. Reference to the examples below will provide
those skilled in the art with working examples of a number of
different systems. Any concentration effective to produce sub-
stantiall~ independent, oriented ~ibers is acceptable according
to the present invention. The particular concentration must be
determined in each case for the balance of product physical
properties and processing efficiency which is desirable and
justified. It is noted that a gelled protein material of the
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type employed in forming TOFU, where the water is restricted from
forming long crystals by the gell s~ructure, cannot be employed
according to the present invention.
` Once prepared, the aqueous protein mixture is frozen
by cooling according to a defined directional pattern to provide
a well-defined, well-ordered fibrous structure produced by the
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ice crystals. As the water is frozen to ice crystals, the
remaining protein mixture becomes more concen-trated. The forma-
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tion of the ice crystals separates the protein material into
distinct, generally paralleI aligned zones. Any means capable
of accomplishing this result is suitable according to the present
invention. The ice crystals form in a latice-work entrappin~
protein in orderly fiber-like portions between the elongated ice
crystals. The zones of protein material are separated from each
other almost completely --- forming substantially independent
fibers of protein when coagulated. ~Iowever, the zones of protein
are not completely independent of each other and are joined at
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`` sufficient locations to bind the individual zones into a branched
or cross-linked structure. The degree of binding achieved is
just sufficient to provide a cohesiveness to the final product
similar to cooked meat, and does not destroy the substantially
independent fibers. This binding, achieved during the formation
of the fibers, eliminates the need for added binder materials.
Freezing is obtainable by cooling at least one surface,
preferably one surface or two opposed surfaces, of the mixture
to below the freezing temperature of the mixture. The cooling or
refrigerating preferably causes freezing to take place throughout
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the thickness of the mass to produce generally parallel fibers,
~ aligned generally perpendicularly *o the cooling surfaces.
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Desirably, the cooling surface or surfaces will be planar;
however, they can have any other, regular or irregular configura-
tion. For example, a single cooling surface can be employed
having a hemispherical, spherical or cylindrical configuration
in contact with the aqueous protein mixture. In these exemplary
situations, the ice crystals, and thus the protein ~ibers, would
form generally perpendicularly to tangents to the surface,
radiating generally toward the center. During freezing, a
boundary between the frozen mi~ture and the liquid mixture
appears and moves in the direction of cooling. At typical
freezing temperatures employed according to the present inven-
tion, and where the cooling surface is not highly irregular, the
boundary will generally conform to the shape of the cooled sur-
face of the protein mixture. Mowever, under other conditions
according to the present invention, the boundary will assume a
somewhat modified shape. It is to be understood that after an
`~ initial thickness of the mixture has been fro~en, the moving
boundary of freezing becomes the cooling surface through which
heat transfer takes place. It is this moving boundary, which then
controls the pattern of the formation of ice crystals and, -there-
forer fibers. The important consideration in all cases is the
production of well-defined fibers having an orderly alignment
similar to natural meat. If needed, the surfaces of the mass not
in contact with the cooling source can be insulated to reduce
heat transfer at these surfaces. It is observed, in most cases,
` that the surfaces not in contact with the one or the two opposed
cooling surfaces exhibit a thickness of somewhat randomly oriented
, fibers. This is because directional cooling at these edges is
difficult to obtain due to heat transfer with external sources.
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This edge portion can be either retained in the inal product or
severed therefrom such as by cutting with a knife, heated wire or
the like. It is also noted that where cooling is effected Erom
two opposed surfaces, horizontal surfaces o~ discontinuity appear,
bisecting the thickness of the frozen mass~ This is apparently
due to the independent crystal growth from each of the opposed
surfaces toward a plane of contact in the middle of the mass.
Many cooling sources can be employed according to the
present invention. For example, the a~ueous protein mixture can
simply be placed in a pan and the pan set on a piece of dry ice
or submerged to a slight depth (e.g. 1/8 inch) in a cold liquid
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such as liquid nitrogen, ethylene glycol, brine, or the like.
Alternatively, a container of the aqueous protein material can be
; placed on a plate freezer or between two opposed plate freezers~
Also suitable would be a moving helt type freezer of the kind
illustrated in U.S. Patents 3,253,420 and 3,606,763. The tempera-
ture employed can be any temperature effective to yield substan-
tially independent, aligned ice crystals. It is noted that,
while the rate of cooling is generally not a factor with regard
to the formation of well defined, well-ordered, elongated fibers
where the cooling is substantially unidirectional, the rate of
cooling does definitely affect the size and shape of the crystal.
Rapid cooling rates result in the formation of minute, microscopic
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ice crystals. Slower cooling or freezing rates result in the
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formation of long, needle-like ice crystals. Preferred cooling
; rates, defined in terms of the rate of advance of the freezing
;` boundary, range from about 0.02 to about 1.0 ft/hr, more prefer-
"~ ably from about 0.03 to about 0.5 ft/hr.
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While there is nothing presently beIieved critical in
the temperature of the protein solution or slurry prior to the
freezing step, it is considered preferably to reduce the tempera-
ture o the solution or slurry to as close to the freezing point
as possible prior to subjecting it to freezing. This is pre-
ferred at the present time solely on the basis of economic~. It
is less expensive to cool a liquid by conventional means with
turbulence and high surface contact with the heat transfer media
than to cool by means of the single or two opposed heat transfer
elements employed for freezing. It is cautioned, however, that
the liquid mixture should not be supercooled prior to the freez-
ing operation as this will result in too rapidl random cooling
and will produce an undesirable, random fiber structure in the
product.
After freezing, the crystalline structure of the
material can be easily observed, if desired, by fracturing the
frozen mass and observing it visually. To retain the integrity
of the individual protein fibers thus formed, the protein is
stabilized according to the present invention by immersing the
frozen mass in an aqueous solution, comprising an edible, water-
soluble material capable of lowering the freezing point of water
and stabilizing the protein. If the substantially soluble
protein is not stabilized prior to heating, such as for heat
setting, the heating will result in excessive bonding of the
individual fibers due to melting of the ice crystal lattice
separating them. As the fibers are then heat set, the~ tend to
form a less distinctly fibrous mass. For many meat analogs, and
especially fish analogs, this excessive bonding of the protein
material is undesired. Also in this regard, the frozen mass
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should not be stored at temperatures which are only slightly
beIow the freezing point of the mass for extended periods of
time. Storage under these conditions will cause recrystal-
lization of the ice and randomization of the fibrous structure.
While this may be desirable to some extent as a means of affect-
ing the texture of a final meat analog, it must only be done
with the knowledge that reorientation is occurring, and it must
be allowed to proceed only to the extent that would be desirable
for a particular application.
The frozen mass is immersed in the stabilizing solu-
tion in any convenient manner using conventional equipment. The
product can be subdivided either before or after immersion.
Water miscible organic solvents have been previously used to
precipitate proteins, and any of these known materials can be
used as the stabilizing material in aqueous solution so long as
they decrease water availability to the protein, decrease the
hydrophilic potential of the protein by causing conformational
changes in the protein, lower the freezing point of the water
and lower the surface tension of the water. The amount of water
available to the protein is reduced simply by the reduced mole
fraction of water in the presence of these stabilizing materials.
Thus, the water is less available for dissolving the protein.
The effective stabilizing materials also enhance the displacement
j of the equilibria.
`~ - helix ~ water
hydrated random protein coil
- conformation ~ water
to the right, thereby adverseIy affecting the solubility of the
proteins. The most effective stabilizing materials which can be
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employed, reduce the surface tension of the water and thereby
reduce the contribution of the water to protein hydrophobic group
adherence. The most noticeable adherence effective in decreas-
ing protein solubility is noticed, in the case of organic solvents,
where the molecules have short, straight-chained hydrophobic
groups. Reducing the freezing point of the water is essential
because the stabilizing material must be able to penetrate the
ice in the frozen product mass.
Among the suitable stabilizing materials are the polar
organic solvents such as alcohols, with e*hanol being preferred
on the basis o its lack of toxicity even where relatively large
residual amounts of this solvent remains in the product.
Ethanol is particularly preferred; however, any solvent can be
employed so long as it has the indicated functionality and is not
toxic at the reasonable levels which may remain in the product
after removal of the solvent by known techniques such as extrac-
tion and drying. Also suitable as the stabilizing or coagulating
materials are the known acids and salts having the necessary
functionality in aqueous solution. If desired, these known salts
and/or acids can be employed in combination with an alcohol, such
as ethanol, or other organic solvent. Such combinations are
desirable from the standpoint that it allows a balancin~ of the
benefits and liabilities of the various stabilizing agents for a
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particular processing or product application. Among the suitable
acids are hydrochloric, sulphuric, phosphoric, acetic and other
; edible acids. Among the suitable salts are the edible ammonium,
alkali metal and alkaline earth sales of these`acids as well as
- other salts having the indicated functionality.
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~' While only exemplary of suitable stabilizin~ materials
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which can be employed according to the present invention,
ethanol will be employed as the stabilizing material in the
following discussion for concisenessO When a frozen mass of
protein and ice prepared in the manner described above is brou~ht
into contact with ethyl alcohol in a coa~ulation bath, a dif-
fusional interchange occurs between the two phases, water in the
protein and ice the crystals, and ethyl alcohol. The ice crystals
melt and water leaves while alcohol enters the protein phase.
As soon as protein comes into contact with alcohol, it is insolu-
bilized and the fibers stabilized. In order to insolubilize the
protein completely, alcohol has to diffuse into the protein
phase thoroughly. After a sufficient length of time, no more
exchange takes place: hence,,a state of equilibrium is achieved
between the two phases. The final equilibrium concentration of
alcohol in the coagulating bath is dependent on ratio of alcohol
to the water in the frozen protein massO The concentration of
alcohol in this coagulating bath affects the freezing point of
solution as well as the diffusion rate and coagulation rate of
protein which are important factors to cohtrol in this process.
When the unidirectionally frozen protein mass is
immersed in the alcohol bath to stabilize the freeze-aligned
ibrous structure, the temperature of the bath must be lower
than freezing point of the protein solution. This immobilizes
free water to minimize rehydration of protein and dissolution of
freeze-aligned structure by water. At the freezing temperature,
water exists as ice crystals in the protein mass. ~hen ice
crystals contact with alcohol,,the ice melts and water diffuses
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1~72392
out; at the same time the protein also contacts with a suffi-
cient concentration of alcohol and is insolubilized. If the
temperature o alcohol bath is close to freezing point of water,
higher than -5C, recrystallization takes place in the frozen
protein block, and the unidirectional fibrous structure disap-
pears and a random structure is formed.
Freezing point depression is dependent on the concen-
tratiGn of solute added in solution. Therefore, the freezing
point of coagulating bath can be regulated by changing the
concentration of alcohol. In order to prevent freezing the
alcohol bath, the freezing point of coagulating solution must be
lower than the processing temperature.
While any effective concentration of stabilizing
material can be employed, in the case of ethanol, it is found
that the concentration should be maintained at above about 10%,
and preferably above 20%. With one particular sample using 5%
ethanol, the protein was completely solubilized and fibrous
structure was disintegrated. At 10%, the protein was partially
! solubilized and fibers were very soft. However, the fibers did
not fall apart. At 20% alcohol, the protein was not solubilized.
The texture was soft due to partial hydration. At higher than
30% alcohol, the protein was completeIy insoluble and the texture
of the fibrous material was hard. When the final equilibrium
concentration of alcohol in this coagulation process was higher
than 70~, the fibers were very fragile due to excessive de~hydra-
tion of protein. It appears that optimum concentration at
equilibrium was about 60% of ethyl alcohol.
Ethanol soluble pigments, carbohydrates, oil and fat
in protein materials are diffused out during this process. This
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is desirable in standpoint of removing pigments and flatulents
from the products. Fat and oil can be recovered and used in
foods.
Once stabilized in this manner, the fibrous mass can
be dried, stored for indefinite periods of time, or heat set
immediately and then stored for subsequent use. It is, however,
presently preferred that the fibers be heat set before rehydra-
tion. The heat setting strengthens the protein fibers. If not
heat set before rehydration, the desirable structural properties
obtained may be diminished.
It is possible through the proper selection of the
; particular type of heat treatment, to effect the texture, color,
toughness, tensile strength, rehydration and water retention
properties of the final product. Textured materials receiving
severe heat treatment tend to retain less water upon rehydration.
-~ However, all textured materials according to the present inven-
` tion preferably receive an amount of heat treatment suficient
to increase the structural integrity of the fibers. ~aterials
receiving mild heat treatment is highIy efficient and gives an
extremeIy good meat-like texture to the final product.
The amount of heat treatment, with or without pressure,
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to stabilize the product varies with the type of protein mate-
rials used. By way of example, dry soy milk fibers are prefer-
ably heat treated in an autoclave under a 15 psig pressure for
from abbut 5 to 10 minutes to stabilize the structure, and
fibers from soy flour, on the other hand, are preferably heat
treated for from 20 to about 25 minutes under the same conditions.
Any combination of time, temperature, and pressure effective to
heat set the protein into substantially independent fibers can
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be employed according to the present invention. It appears that
heat treatment at a tempera*ure ranging from about 100C to
about 120C for a time of from ahout 5 to abou-t 30 minutes is
adequate depending upon the texture desired in the final product.
The exact times, temperatures, and pressures employed will be
easily determinable by those skilled in the art for a wide
variety of products. Reference to the examples below will show
a number of specific heat treatment operations which will guide
those skilled in the art.
Typical of the heating means which can be employed are
conventional autoclave or steam chamber devices capable of pro-
ducing pressures of up to about 20 psig and temperatures of up
to about 130C. Also suitable would be electric or gas-fired
infrared ovens capable of operating under conditions of high
reIative humidity. The use of moist heat in such devices, or in
the autoclave or steam chambers previously mentioned, aids in
providing a more complete coagulation or immobilization of the
protein materials. The specific heating means employed is not
critical to the present invention. All that is necessary is
that the heat be sufficient in time and intensity to coagulate
or immobilize the protein sufficiently to substantially prevent
loss of the individual protein fibers upon rehydration.
A~ter heat setting, the fibrous protein material can
be marketed as is, or rehydrated immediately to obtain a more
meat-like texture. The product is easily rehydrated by soaking
in water for a period o time effective to obtain a desired
water content. The rehydrating solution can contain acids for
; neutralizing any residual alkali, or flavorings, emulsified
fats, flavor enhancers, condiments, sugars, heat coagulable or
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soluble proteins, amino acids, and the like. In this manner,
the product can be` modified to have the taste as well as the
texture of meat. Of course, as indicated previously, these
ingredients can also be employed in the a~ueous protein mixture
before freezing. Experience with particular recipes will dictate
at what point these additives are employed.
The following examples are presented for the purpose
of further explaining and illustrating the present invention,
and are not to be taken as limiting in any regard. Unless
otherwise indicated, all parts and percentages are by weight.
EXAMPLE I
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To prepare a texturized soy protein product having
highly-oriented, well-defined fibers, a soy milk is used as a
protein source. The soy milk is prepared by soaking 600 grams
of soy beans overnight in water~ changing the water several
times. The soaked beans are then hot ground with boiling water,
the water being present at a 10:1 ratio with regard to the soy
beans. The resulting slurry is heated to boiling and held there
for lS minutes, and filtered through a double layer oE cheese-
cloth. The residue on the cheesecloth is discarded and the
level of solids in the supernatant is determined. The p~l of the
supernatant is then adjusted to 7.5 using 2N sodium hydroxide,
and an antioxidant is added to the supernatant at a level equiva-
lent to 0.02~ of the fat content. Because full fat soy beans
are employed, the fat content of the superna-tant is about 1/4
the weight of the solids present. The soy bean milk is then
placed in an aluminum pan to a depth of about one inch. The pan
is placed on a block of dry ice ~-76C) which extends across the
entire bottom surface of the pan. Unidirectional ice crystals,
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- substantially perpendicular to the bottom of the pan, are genera-
ted. The mass is completeIy frozen in about 30 minutes. The
frozen mass is removed rom the pan and immersed in 95~ ethanol
at the weight ratio of 1:4 for 8 hours with stirring at a temper-
ature ranging from -5~C to -lO~C. The stabilized fibrous material
is pressed by applyin~ force perpendicular to the direction of
fibers to hasten the release of ethyl alcohol trapped in the
spaces between the fibers. The pressed product is then air
- dried to remove water and residual ethanol. ThiS drying process
strengthens the structure. This dried material is autoclaved at
15 psig for 10 minutes to strengthen the structure. The heat
set material is then rehydrated by soaking in water for about
20 minutes to yield a product having discrete, long, soft, chewy
fibers.
EXAMPLE II
The procedure of Example I is repeated, but thi~ time
inmersing the aluminum pan containing the soy bean milk into a
propylene glycol freezing bath (-32C) to a depth of about 1/8
inch instead of placing it on the dry ice.
EXAMPLE -III
The procedure of Example II is repeated, but this time
:: the stabilized fibrous material is not pressed, but is placed in
a vacuum chamber for 15 minutes to remove residual ethanol.
EXAMPLE IV
A fibrous soy protein product is prepared from soy
protein isolate. Here lOOg of so~ protein isolate ~91~ protein)
was mixed with 900g of water to ma]~e 10% solution and pH was
~ adjusted to 7.0 - 8Ø This solution is placed in a pan to a
- depth of about one inch and frozen and stabilized as described
~; 30 in Example III.
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EXAMPLE V
A fibrous peanut protein product is prepared ~rom
peanut protein isolate. Here 150g of peanut protein isolate
~93% proteih) was mixed with 850g of water to make 15% solution
; and pH was adjusted to 7.0 - 8Ø This solution is placed in a
pan to a depth of about one inch and frozen and stabilized as
described in Example III.
EXAMPLE VI
A fibrous egg albumin product is prepared from fresh
egg white. The whites of several eggs are separated from the
yolks, placed in a pan, frozen and stabilized as described in
Example III. Here 10~ egg albumin solution prepared from egg
white powder can be successfully used.
EXAMPLE VII
~ .
A fibrous fish protein product is prepared from a 15%
aqueous mixture of fresh fish meat. To prepare the aqueous
mixture, 150g of lean fish meat is homogenized with 850 ml of
,
cold 3~ NaCl aqueous solution in a Waring Blendor* at high speed
` for about five minutes under vacuum. The resulting homogenate
mixture is then placed in a pan, frozen and stabilized as des-
cribed in Example III.
EXAMPLE VIII
: A fibrous milk protein product is prepared from fresh
`whole milk. The milk is placed in a pan, frozen, and stabilized
according to the procedure of Example III.
EXAMP~E IX
A procedure of Example I is again repeated, but this
time the soybean milk is concentrated as ollows:~ The pH of the
soy bean milk is adjusted to 4.5 by adding HCl (IN). The
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resulting precipitate is separated by centrifugation at 5,000 x
G for 20 minutes. The supernatent is discarded. The precipi-
tate is transferred to a mixer and mixed with water for 20
; minutes to get a smooth and concentrated (I8~ to 20% solids~
soybean milk. The soybean milk slurry is then adjusted to a pH
of about 7.5 using 2N sodium hydrozide and the resulting solu-
`' tion is placed in a pan,~frozen and further processed as in
Example I.
Many modifications and variations of the present
invention will be apparent to those skilled in the art upon
; reading the above disclosure. It is intended that all such
modifications and variations be included within the scope of the
present invention which is defined by the following claims.
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