Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
Case 81015
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B~CKGROUND OF THE INVE~TION
Imitation textured products~ prepared from low cost raw
material, have been proposed to replace the more costly natural food
products. The most prolific development h~s occurred within the field of
imitation meat products.
Ihe early synthetic meat-like extrudate technology involved
forming a vegetable protein slurry (e.g~ soy fla~es and water),
mechanically working the soy flour and water within the barrel of an
extruder under elevated pressures and temperatures to form a molten mass
and extruding the molten mass through an orifice into the atmosphere.
This resulted in a puffed extrudate which simulated the fibrous
character of meat products.
Subsequently issued patents modified the extrusion process to
produce a non-expanded, m~at-like extrudate. United States Patent No.
3,886,299 by Feldbrugger et al. discloses a dense, substantially unpuffed
fibrous, meat-like product. I~he Feldbrugger et al~ process initially
entails forming a dough o~ the water and proteinaceous ~aterial. The
dough is then fed to an extruder equipped with a heated channel of
decreasing volume adapted to simultaneously elongate and thermally
coagulate the dough and to release the compression without forcing the
dough through a die whi]e maintaining the pressure drop below 100 psi.
Although Feldbrugger et al. infer the water content may broadly range
between 20% and 65%, the working examples show that from 25% to 38% water
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is needed to form the fibrous dough and meat-like product. In U.S.
Patent No. 3,950,564 by Puski et al. an extrusion process for producing a
dense, fibrous, meat-like substitute is also disclosed. The dense,
fiberous extrudate of Puski et al. is reportedly achieved by passing a
protein 50~70~/water 30-50% mix through a plurality of zones decreasing
pressures and temperatures. The final ~one, preceding the shaping die,
is reportedly maintained at a pressure of less than 100 psi and a
temperature less than 212F. Puski et al.speculate that the higher
moisture content, reduced temperatures, extensive shearing action, open
space within the extruder barrel, step-wise pressure reduction
contributes to textural imp~v~el,~nts. ~lski et al. stresses that the
configuration of the annular spacing between adjacent screw sections of
the final, notched, tapered screw or cone section of the extruder and
alignment of the open section within the barrel preceding the extrusion
die head contributes to an extrudate having a more elongated3 fibrous
mass, plate li~e structure.
In the preparation of these meat-like extrudates, the extruder
design, extrusion conditions and the composition of the feed materials
are especially adapted to produce a fibrous, meat-like structure in the
finished product. Considerable mechanical working and exposure of the
molten mass to frictional forces contributes to the creation of the
desired fibrous character. Although this extrusion tec~mology is
suitably adapted for preparing synthetic meat-like products, it is
inapplicable to the preparation of imitation vegetable products.
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In view of the high cost of many vegetable products such as
mushroomsg the inventors desired to produce imitation vegetable products
from a low-cost-raw material. In pursuit of this objective, the
inventors discovered that under certain carefully controlled extrusion
conditions it was possible to produce an extrudate which simulated the
eating, flavor and textural attributes of a high quality vegetable
product.
DESCRIPTION OF IHE INVENTION
According to the present invention there is provided a method
for preparing imitation vegetable products from proteinaceous materials
which comprises: transferring under superatmospheric pressure and a
ternperature between about 130C. to about 160C. a molten mass containing
proteinaceous material and at least 110 parts by weight ~ater for each
lO0 parts by weight proteinaceous material into a confined cooling zone;
cooling themolten mass within the cooling zone to a temperature below the
boiling point of the water contained within said mass, solidifying the
flowable mass by extrudi~g the cooled mass into a zone maintained at a
temperature below the solidification temperature of the ~lowable mass;
piercing the solidified extrudate into the configuration of an imitation
vegetable piece and irnpartir~ the textural characteristics of a vegetable
product to the pierced extrudate by heating the pierced extrudate under
superatmospheric pressure in the presence of a saline solution at a
ternperature greater than 95C.
Proteinaceous materials used to prepare the imitation vegetable
pieces may be obtained from a variety of protein sources. Illustrative
~(37~3~
thereof are proteins derived from animal, poultry, vegetable, microbial~
marine, etc. sources. Exemplary proteinaceous materials include an~mal
proteins such as milk, whey, kerat m, globulins, etc., fish proteins such
as fish meal, proteinaceous materials obtained from microbial sources
(e.g. yeast, etc.) and vegetable proteins. Advantageously the protein
materials have a protein content of at least 40% by weight (d.s.b.) and
are derived from a vegetable source and particularly those obtained from
vegetable seed materials such as wheat, corn, oats, rye and legumes.
Proteinaceous materials obtained from defatted leguminous materials such
as soybean, peanut 5 cottonseed, etc. are particularly effective source
materials for producing the imitation vegetable products of this
invention. The preferred proteinaceous materials are soy proteins and
particularly those which contain (on a dry solids basis) at least 70% by
weight soy protein such as soy protein concentrates and isolates with the
soy protein concentrate being an especially suitable raw material.
The amount of water combined with the proteinaceous materials
affects the textural characteristics of the finished product. If less
than llO parts by weight water for each lO0 parts by weight protein
material is used, excessive mechanical working, shearing and fi7ictional
forces will occur within the extrusion mass. Such excessive forces will
result in the development of a tough, fibrous~ meat-like texture.
Conversely, an excessive water level (e.g. greater than 150 pbw? yields
an extrudate product of insufficient structural strength to retain its
integrity when retorted in saline solutions. To achieve the textural
characteristics of a vegetable material product the water content of the
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extrusion mix will typically range ~rom 55% to about 60% of the total
protein material and water weight. On a 100 parts proteinaceous material
weight basis (d.s.b.) the extrusion mix will advantageously contain from
100 to about 135 parts water for each 100 parts by weight proteinaceous
material and preferably about 115 to about 125 parts by weight water.
Other additives such as preservatives, coloring, flavoring,
sweetening, plasticizing, texturizing, etc. agents may be incorporated
into the base mix prior to extrusion or alternatively to the saline
solution. Such additives may be used to modify the desired textural,
color and organoleptic properties of the imitation vegetable product. If
such additives are incorporated into the extrusion mix they will
generally comprise less than 15% and most typically less than 10% of the
protein material dry substance weight. Metal salt additives such as
calcium chloride, sodium chloride, etc. may be incorporated into the
extrusion mix to satisfy the subsequent saline solution requirements.
Such netal salt additions tend toughen the texture of the extrudate and
are usually omitted from the extrusion mix in the manufacture of the
tender textured im~tation vegetable products. Organic and inorganic
coloring additives can also be effectively included in the extrusion mix
to impart the desired coloring affect to the imitation vegetable premix.
Plastîcizing agents such as edible oils, lecithin~ polyhydric
alcohols (e.g. glycerol, propylene glycol, so~itol~ mixtures thereof
and the like) may be effectively included to enhance pliability and tenderness
of the extrudate. ~e most appropriate plasticizing level will depend upon
the physical, chemical and organoleptical properties o~ the plasticizers.
~9(~7~9:~
Plasticizing additives such as the polyhydric alcohols may be satisfactorily
used at higher concentrations than other plasticizing additives such as
lecithin. In general, the added plasticizing agent level will normally
be less than 25 pbw for each 100 parts by weigJht proteinaceous materiaI~
The polyhydric plasticizing additi~es will effectively increase the water
boiling point which permits higher temperatures to be used in the cooling
and extruding of the product. The plasticizing additive levels will
advantageously range from about 5 to about 15 pbw for polyhydric alcohols
and about 0.25 to about 2 pbw for lecithin.
Flavoring agents thermally stable under the extrusion conditions
herein may also be incorporated into the extrusion premix. The thermally
unstable flavo~ing and coloring additives are advantageously omitted
from the extrudates.
The feed materials (including the proteinaceous material, water
and other desired additives) are charged to the extruder. The feed
materials are advantageously converted into a ht~mt~gt~n~us mass prior to
their submission to temperatures of 1~0C. or higher. Conventional
mixing equipment or adequate premixing techniques within the extruder
prior to the conversion o~ the feed materials into a molten mass may be~
used for this purpose. Further improvements in textural properties are
obtained by initially placing a m3~or portion of the water-soluble
protein into aqueous solution prior to the mechanical working of the feed
materials to a tem~erature of 130C. or higher. In the preferred
e~bodiments o~ the invention, the raw materials are initially mixed
together at a tem~erature of less than 40C. before being exposed to
temperatures of 130C. or higher.
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The homogeneous admixture is then converted to a molten mass
under superatmospheric pressllres at a temperature ranging from 130C. to
about 160C. The molten mass-for~Dilg temperature and extrusion conditions
are carefully controlled so as to develop the imitation vegetable textural
properties. Excessively low extrusion temperatures and water levels create
viscosity problems within the coolir~ zone and a grainy, fibrous textured
product. Conversely excessive charrlng and product toughness arise from
prolonged exposure at temperatures in excess of 155C. Advantageously,
the extrusion temper~atures rar~e from between 135C. to 155C. The
preferred operational temperatures range from about 140C. to about
150C.
The extruders used to prepare the i~itation vegetable products
are specifically adapted to minimize the amount of mechanical working,
shearing and frictional forces placed upon the protein composition. The
total amount of power required to force the product through the extruder
provides a guideline for ascertaining the extent of mechanical working,
shear and friction. Extrusion processes which extensively work, shear
and cause considerable friction require more power than tho æ operated
under low working, shearing and frictional conditions. Extrusion devices
requiring less than 100% operational increase in power over those
normally required to operate the extruder on a no-load basis are
advantageously used to produce the extrudates of this invention.
Compression and/or twin screw extruders such as conventionally used by
the plastic industry have been found to be particularly effective for
this purpose. Under the preferred operational conditions, extruders
which require less than a 30% power increase (usually between about 5%
to about 20% increase) are used to prepare the extrudates.
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The molten mass is extruded under conditions which prevent the
volatile constituents from formir~ a porous or puffed extrudate. Puffing
of the extruda~e is avoided by cooling the molten mass to a temperature
below the boiling point of the volatile constituents prior to exposing
the extrusion mass to ambient temperatures and pressi~res. The cooling
temperature should be maintained sufficiently high so as to permit the
cooled mass to continuously flow through the cooling zone but low enough
to prevent puffing. The required cooling temperatures will depend upon
the actual boiling point of the volatlle constituents of the extrusion
mix. If the extrusion mix contains additives that tend to elevate the
water boiling point te.g. metal salts~ plastici ærs, polyhydric alcohols,
sugars~ etc.), the cooling zone temperature may exceed the normal water
boiling point (i.e. 100C.) by 10C. or higher. For most extrudates,
the cooling zone will typically be maintained from about 35C. to
100C.,and most typically within the ~5C.-90C. range.
The coolir~ zone is suitably designed so as to confine the mass
under superatmospheric pressure until it c~n be extruded into an ambient
zone without puffing. Conventional plastic extruders equipped with a
water-jacketed cooling die assembly bolted directly onto the exit plate
are satisfactory for this purpose.
The shape and configuration of the opening cooling assembly
orifice should be designed to mini~ize the mechanical working and
frictional forces. For most operations the cooling assembly cross-
sectional area will range from about 10% to about 100% of the average
cross-sectional area of the extruder barrel (most typically from about
25% to about 50%~. Orifices adapted to produce extrudates in ribbons
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or sheets measuring from about 0.05 t;o about 0.25 ~ches thick and
preferably from about o.o8 to about 0.15 inches are particularly effective.
If desired the extrusion device may be equipped with a
plurality of zones~ each of which is operated at different ternperature
and pressure. For example, the first zone may be operated to provide a
homogeneous adTnixture of the proteinaceous material and water, the next or
succeeding zones adapted to convert the adrnixture into a hot, fluid,
molten rnass of rnaterial and the flnal zone to cool the product below the
boiling ternperature of the volatile constituents.
After sufficient cooling~ the Mowable and cooled mass is
solidified. This can be no~nally accomplished by extruding the cooled
mass into an aTribient zone. In the preferred embodiment of the invention~
the extrudate is forced through a cooling die assernbly which is adapted
to yield a flat belt- or sheet-like extrudate measuring approximately
o8 to about 0.15 inch thick. The extruded product can be easily cut or
starnped into the desired piece during this processing stage. The solidified
extrudates are most generally characterized by a non-fibrous, smooth surface
appearance. The high water-retention level has a plasticizing effect
upon the solidified product. This imparts a flexible and pliable character
to the solidified product. The extrudates have a su~ficîently high tensile
strength and low elasticity to pe~nit mechanical-drawing of the product
through a cutting device. In contract to the comnercially available, unpuffed,
retortable extrudates which often have void spaces in excess of 0.5 void
cm3/rnass cm3, extrudates of less than 0.1 void cm3~mass cm3 may be prepared
under this invention.
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The extrudates issuing ~rom the cooling zone are susceptible to
microbiological spoilage. Spoilage can be alleviated by incorporating a
preservative into the base formula, cooking the solidified extrudate or
by drying the extrudate. ~ne inclusion of prese~atives is generally
undesirable since such preservatives will often adversely affect the
textural and taste qualities of the imitation vegetable product. Drying
the extrudates will effectively inhibit or prevent microbiological or
enzymatic degradation and is useful when the extrudate pieces are
intended to be stored. Reducing the ~otal water content of the extrudate
to less than 15% (most typically from about 10% to about 15%) will
generally be sufficient to microbiologically protect the dry extrudate
agaInst microbial spoilage.
The solidified extrudates are pierced into the configuration of
the desired imitation vegetable product. The term "piercing" is intended
to broadly enco~pass a wide variety of techniques for cutting, partially
cutting, scoring, stam~ing, perforating, etc. the extrudate product into
the shape of a vegetable product or vegetable piece. The piercing device
may be designed to completely cut or partially cut the extrudate. If
the extrudate is partially cut or stamped, the initial scoring of the
extrudate should be sufficient to permit its subsequent separation.
Partial cutting can be conveniently used when it is desired to dry the
piece prior to the retort cooking step. Upon impact, separation of
vegetable pieces from the extrudate can be achieved by breaking or
shattering the dry extrudate along its scored lines.
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Cooking the extrudate under pressure in the presence of a saline
solution adJusted to a pH ranging from about 5.6 to abouk 6.4 is necessary
in order to impart the textural attributes of an imitation vegetable product
to the extrudate. The extrudates typically absorb or retain from about
2 to about 5 times their dry weight in water. The saline solution
requirements may be provided by pre-soaking the extrudate pleces in a
saline solution followed by retorting of the extrudate within the
prescribed pH range. Alternatively the extrudate may be combined with a
pickling brine adJusted to the appropriate pH, sealed in a container and
cooked under pressure to provide a canned imita~ion vegetable product.
A sufficient amount of a metal salt should be present during
the cooking to impart the desired vegetable product textural attributes
to the extrudate. Relatively dilute saline solution (e.g. 0.05M or higher)
are generally sufficient for this purpose. Excessive salinity (e.g. lM)
will not generally adversely affect the textural properties but will
result in an undesirable salty taste. Pragmatically the saline concentration
will typically range from about O.IM to about 0.3M and most typically
from about 0.15M to about 0.25M.
The pH at ~hich the extrudate pieces are cooked under pressure
also has a significant affect upon texture. Excessively low pH conditions
result in a fibrous texture while a pH of 6.5 or greater produces an
excessively mushy or soft text~e. Retort cooking at a pH ranging from
about 5.5 to about 6.5 (preferably at a pH 5.8-6.3) will generally impart
the desired vegetable textural characteristics.
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Another significant factor affecting the textural properties is
the retort cooking temperature. Although temperatures of less than
110C. may be used under prolonged cooking periods,the cooking tem~erature
advantageously ranges from about 115C. to about 135~. with particularly
effective results being achieved at cooking temperatures ranging from
about 115C. to about 125C.
The il~itation vegetable products produced in accordance with
the present invention differ from conventional meat extrudatesO The
dry extrudates are relatively free from internal voids (e.g. less than
15% of the mass and most typically less than 8%). Notwithstanding the
compacted dense e~trudate st~ucture, the extrudates are capable of
adsorbing several times their dry weight in water. When retorted in the
presence of saline solutions, the extrudates will no~nally adsorb water
in an amount of at least 2.5 the extrudate dry weight (e.g. 2.5-5) and
advantageously ~rom about 3 to about 4 times their dry weight. The highly
compacted extruded product is comprised of a plurality Or concentric
lamina, each of which is aligned substantially parallel-to the planar
surface of the extrudate (i.e. along longitudinal axis of extrusion).
In the dry form, a cross-sectional cut transverse to the direction of
extrusion~ macroscopically reveals a product substantially free of visible
voids including appreciable separations or void spaces between the l~min~.
Visually the extrudates appear to be a solid piece. When hydrated by
retorting~ the la~inated structure within the extrudate becomes more
readily discernible. Unlike the dry extrudates which appear substantially
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free rrom a multiplicity of lamina, the retor~ed and hydrated pr~duct
macroscopically reveals a plurality of very thin laminae. In the retorted
and hydrated rorm, the lamina can be separated (e.g. by peeling) into
distinct lamina which will individually measure less than about 0.5 mil
in thickness. Advantageously the lamIna which form the lamin2ted str~cture
will have a thickness of less than 0.3 mil and preferably less than 0.l
mil in thickness. Ihe retor1-ed and hydrated extrudates are also generally
characterized as a pliable and tender structure which possesses sufficient
Physical and str~ctural integrity to resist ~isintegration and laminate
separation during and af~er retorting.
~{Al~E
Imitation mushroom pieces were prepared by thermoplastic
extrustion Or a soy protein concentrate under non-expanding extrusion
conditions, cut~ mg the extrudate in the shape of mushroom pieces and
retorting the pieces in brine at a pH 5.8.
Ihe non-expanded ext4rudates were prepared by pre-blending one
hundred pounds o~ soy protein concentrate with 135 pounds water, metering
the pre-blended mixture into a Bonnot extruder (Model 2 l/41'~
at a rate of 60 pounds per hour. Ihe first section of extruder
(l0 inches~ was maintained àt 38C., the second at;65C; and the third and
fourth sections at 150C. The cooling section was labricated rrom two
carbon-hardened flat steel sheets each measuring l inch thick by 8 inches
by 6 inches. One of the flat steel sheets was machined on one side along
- PR0CON 2000 - M~nufactured and sold by the A. E. Staley
ManuractuFing Company, ~ecatur, Illinois
* Trade Mark
~(17~
the center of its longitudinal axis into a cavity measuring 3/32 inch thick
through its entire length. Three cooling holes ]/2 inches ID were bored
through each sheet at intervals of 1/2 inch, 3 inches and 5 inches from
the cooling zone exit with each bore being positioned about 1/4 inches from
the cooling zone cavity. The cool:Lng pipes were equipped with adapters
to receive heated water as a coolant. Assembled~ the cooling zone provided
a ribbon-shaped cavity measuring 6 inches wide, 3/32 inches high and
6 inches in length
A forming æction (adapted to be bolted directly onto the
extruder head and the cooling section) was made from carbon-hardened
steel piece measuring 6 inches wide, 5 inches high and 5 inches in length.
The orifice of the forming section was adapted to fit onto the extruder
head and machined to the same orifice size as the extruder head orifice
(1 inch ID). The remaining orifice portions of the forming section
~as designed to radiate inwardly in an eliptical funnel-shaped form so
as to coincide with the configuration of the cooling section orifice.
Cooling water at 38C. was used as a coolant in the cooling zone.
~e extruder and cooling assembly were preheated by heatin~ the
sections to the operational temperature and thereafter allowing a small
amount of water to pass through the extruder. After steam had issued
from the cooling sections for 5 minutes~ the water and soy concentrate
premix was fed to the extruder at a rate of 60 pounds/hour. The hot
molten protein exiting from the extruder passed through the forming
section into cooling sections. The product exited from the cooling zone
at 65 C. and contained about 70% moisture. ~he extruded product was
~307~3L
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very flexible with sufficient tensile strength to be recovered upon
drawing reels.
The power requirements ~or the unloaded or empty extruder was
10 amps wlth a 10% increase in power ~11 amps) being required to operate
during the product extrusion.
The rlbbon-shaped continuous extrudate (6 inches wide and
1/8 inches height) was scored to a depth of 0.10 inches with a cutting die
of a mushroom configuration and oven-dried (180F.) to moisture content
of 6%. Separation of the mushroom pieces was achieved by impact shattering
of the sheets in a rotary tumbler which caused the mushroom pieces to break
cleanly along the scored lines into discrete mushroom pieces.
m e volume, weight and true density (e.g. picnometer) of the
dried mushroom pieces were then determined. The bulk density of the
mushroom pieces was 1.28 g/cm3 + 0.05 and a true density tby air picnometer)
was 1 35 g/cm3. m e specific volume of the bulk piece was 0.781 cm3/gram
and the specific volume of the true density was o.7LIo cm3/g. A void volume
of 0.052 void cm3/mass cm3 was then determined by the following e~uation:
B - T = V
wherein B represents the bulk specific volume cm /g~ T is the true specific
volume in cm3/g and V equals the void volume cm3/mass cm3. A co~,mercial
meat-like retortable extrudate was likewise analyzed. The void volume of
this product was 0.604 void cm3/cm3 mass.
The dry mushroom pieces were then boiled in a hydrating brine
consisting of 1000 pbw of water, 12.5 pbw salt, 0.5 pbw citric acid and
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200 pbw pleces at a pH 5.8 ror one hour. T~e unadsorbed brine was drained
rrom the cooked hydrated pieces and the dralned pieces were then ~illed
~nto 603 x 700 eans followed by a fllllng of the cans with a 65C~ paek
brine consisting Or lO00 pbw water, 12.5 pbw salt, 0.5 pbw citric aeidg
1.29 pbw ~cGormick ~30083 flavor and ~FW mushroo~ f~avor #68060a The
contents were then exhausted at 85C., cans closed and retorted for 75
ninutes at 241F.
Analysis of the retorted pieces indicated the pieees had
adsorbed 3.5 times their dry weight in brine. The pH o~ retorted pieees
was 5.9. ~ne retorted pieces closely simulated the appearanee as well
as the sueculent texture and taste Or natural mushroo~ pieces. The
pieces were uni~ormly dispersed as individual pieces throughout the
packing brine. Upon storage lor several n~nths, the imitation mushxoom
- pieces retained the freshness and quality ~f the freshly packed product
without any evidence Or physical~ ehemieal, enzymatie or mierobial
deterioration.
* Trade Mark
. ,
