CA1116009A - Protein texturization - Google Patents

Abstract

ABSTRACT OF THE DISCLOSURE

A bland protein product having a texture and mouth feel simulating animal meat is prepared from a dough-like mixture of proteinaceous material and water. The proteinaceous material can comprise relatively low protein content blends or even single ingredients such as soy flour. The process comprises continuously extruding the protein dough in the form of a relatively thin sheet of semi-rigid protein material into a confined treating zone while simultaneously subjecting the thin sheet in the extrusion die to externally applied heat to texturize both surfaces of the sheet before it enters into the confined zone. In the confined zone a stream of heated gas is directed at the thin sheet of surface-texturized protein to break off the leading segment of the sheet and further to propel the segments through the confined zone where additional texturization takes place. Finally, the protein segments are passed through a back pressure means at the end of the confined zone, and recovered in usable form. Apparatus for performing this process is also disclosed,

Description

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13~CKGE~OUND OF TEIh` INV¢NTION

Field of the Invention ~ This invention relates to the treatment of untextured protein materials i to form a product possessing the flbrous texture and rnouth feel properties of animal meat.
. ' De,scription oE the Prior Art The food industry has spent much eEfort over a span o~ many years and has expencled large sums of money in an attempt to utilir.e non~meat proteins~ such as those derived from vegetables, as additives to or substitutes for anirnal meat products. It long has been recognized that the ever-increasing worldwide Eood shortage could be in material part obviated iE only such relati~ely inexpensi~e materials could be converted into products So closely approximating the naturally occurring food material that public I acceptance vrould be achieved. One of the major roadblocks encountered ¦ by the industry has been the inability to impart the natural and accustomed chewy, Eibrous tex-ture to vegetable protein materials. Animal meat products inherently possess a texture giving them a definite 1'mouth feel"
whlch is clearly recogniæed and strongly pre~erred. Vegetable proteins in their natural state generally take the form oE amorphous powders which, despite their unquestioned nutritive value, possess mouth ~eel characteristics wholly unacceptable to the consumer as a meat su~stitute. Moreover, vegetable proteins normally are characterized by objec-tionable "beany" -Elavors which the indusltry has been unable to remove or xnask.
In recent years a number oE processes and apparatus have been ~ de~eloped for treating vegetable protein material to produce a bland 1~ , i, ¦¦ texturized product. None o~ th~sc processes~ h~w~ver, has achieved any substant;ve measure oE commercial s~lccess.
I The first generation o~ these prior art techniques 1nvolved the wet ¦I spinning process disclosed in Boyer, W.S~ 2~730J~47. This process 5 ¦ produces a fibrous product by extruding a plurality of ine streams of an aqueous solution of protein into a ~hemical coagulating bath. The protein coagulates into fine fibers which are collected together and treated to Eorm an edible textured protein product. The wet spinning process sufers rom a number o drawbacks in addition to its general ailure to produce ~n adequately texture;d ploduct as discussed above. The equipment employed to per~orm this process is extremely sophisticated Eor the food industry and represents a very high initial cost problem. Adding urther to the economic infeasibilit;y of the product produced by the wet spinning I process is the expensive starting materials wilich must be employed.
15 ¦ Moreover, product uniformity is diicult to achieve due to the general complexity of the process and the numerous palameter control problems presented.
The second generation technique advanced in this area is the extrusion cool~ing process disclosed in Atkinson, U.S. 3,488,'170, in which a protein mass is subjected to severe physical workir~g at an elevated temperature and ther eafter extruded at an elevated temperature and pressure ¦
through an oriEice into a medium of lower pressure and temperature. This process suers rom high equipment costs and is extr emely energy intensive ¦
¦ due to the extreme temperature and pressure requiremi~nts. In addition, 25 ~ the product produced by extrusîon cooking has a very low density which ~. !
,, , ,'' ' i 61~0 ¦ swells up in water to give a "spongy" texture. Moreover, the product ¦! contains objectionable Elavor notes in addition to the i'beany" Elavor ! originally present in the starting materials which are apparently imparted to the product by the severe processing steps. Other patents demonstrating the current state oE the art in re$pect to the e~trusion texturizing approach include Hale, U,S. 3,447,92~); Jenkms, U.S. 3,496,858; ~nker, ~,S.
3,684,522; Strommer, U.S. 3,778,522, Lang, U.S. 3,~00,053; Atkinson, U.S. 3,812,267; and ~ang, IJ.S. 3,81~L,823, The third generation oE development in the protein texturi~ation involves the use of steam a.s the texturi~ing medium. Exemplary of this approach are StrommerJ U.S. 3,7S4,926 and 3,863,019 which ~reat either finely divided protein particles or siurries with steam and Heusdens U. S. Re. 28,091 which employs a steam treatmenl oE protein slurry ~ollowing complex hydration steps. Products produced by these processes also possess the general problems o poor texture and Elavor discussed above. In additlon, the product has low density problems similar to the second generation extrusion coo~ed products in that on hydration they tend to be very soEt. 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 heal; coagulahon of undenatured protein disclosed in RusofE, U.S.
Re. 27~790. -Notwithstanding the veritable plethora oE prior art attempts to satis~actorily te~turize vegetable proteins--no one to date has made any 25 ¦I really substantial progress toward the desired goal. The present absence -4~

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from the marke~ of any commercially accepted consumer products based on vegetable protein demonskrates c]early that the problems involved simply have not been solved. Indeed, those meat analog products which have found their way to the super-market shelves generally have been met with little or noconsumer 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, 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 procedures that initial equipmen~ and operating osts 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 diminishi~g availability of animal meat protein products, it is clear that an inexpensive, consumer-acceptable, high protein food product based on texturized vegetable 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 thin discrete segments of relatively dense protein material having a fibrous texture simu'lating that of natural meat.

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It is an ob~ect of an aspect of the present invention to provide a process and apparatus which wiLl produce a bland flavored 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~
It is an ohject of an aspect of this invention to provide a texturizing process and apparatus which will produce such a product at a much lower cost d.ue to lower ini-tial equipment costs and lower energy requirements.
It is an object of an aspect of the present invention ;
to provide a high quality texturized protein product from :;
relatively inexpensive, low protein starting mat~rials.
Various aspects of the invention are as follows:
A method for producing a relatively dense texturized protein product with a unidirectional laminated surface structure comprisin~: (a~ mixing untextured protein material and water to form a protein dough, said dough containing from about 60 to about 73~ solids; (b) advancing said dough to a die means at a temperature below that at which -texturization takes place; (c) continuously extruding a relatively thin sheet of semi-rigid protein material through said die means while simultaneously texturizing both surfaces of said thin sheet as it passes through said die means by externally apply-ing heat to both surfaces of said sheet; (d) passing said extruded sheet directly into a confined treating zone while simultaneously directing a heated gaseous stream at said extruded sheet as it enters said confined treating zone to break off the :Leading segment of said extruded sheety said gaseous stream further propelling said segments through said 30 confined trea~nent zone; passing said protein seg~ents tB
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through a back pressure maintaining means disposed at the discharge end of said confined treating zone; and If) recovering the texturized protein segments.
Apparatus for texturizinq protein ~hich comprises die means for extruding a continuous~ relatively thin sheet of semi-rigid protein material; means for external-ly applying heat to both surfaces of said thin sheet as it passes through said die means to effect surface texturization of said thin sheet; means defining a con-fined treating zone communicati.ng with said die means;means for - 6a -,:, . :
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¦~ directing a heated ~aseo-ls stre~m ~t saià extruded thin sheet as it enters ¦~ said confined zone to break off the leading segment of said extruded sheet;
il and means Eor recovering said texl;uriæed protein material.

l B~IEE I~ESCF:IPTION OF THE D~AWINGS

Figure 1 represents a scl~lematic of one embodiment of the appa~ratus of the present invention.
Figure 2 i5 a sectional view taken along lines 2-2 showing the slitting means at the discharge from the die assembly.
~ Figure 3 is a photomicrograph of a section oE the product produced 10 I by the present Invention, observed at 50~.
Figure 4 represents a series of photomicrographs of an interior ~ section oE the product produced by the present in~rention; 4a is at 2 5~g;
¦~ 4b at 50X; 4c at 100~; 4d at 300X; 4e at 500X; 4f at 1000~; and 4g at 1500X, ¦ Figure 5 represents a series o~ photomicrographs o an exterior ~5 ~ section; 5a is at 50X; 5b at 100X; 5c at 30,0~; 5d at 500X; 5e at 1000~; and ~f at 1500X.
Figure 6 represents a serles oE photomicrographs of the product of the prior art extrusion cooking process; 6a is taken at 50X; 6b at 100X;
6G at 300~; 6d at 5U0X, 6e at 1000X; and 6f at l500X.

DEI'AILED DESCRIPTION OF THE INVE:NTION

¦ The present invention is directed to a process and apparatus for texturizing protein material. The terxn texturizing as used herein and widely understood in the art reEers to the process oE changing globular i arnorphou6 particles of protein into fibrous continuous phase protein material with structuYal identi-ty.
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 abou-t 1 part tcxturized protein is mi~ed with 10 parts of a 1% salt solutiorl and sealed in a can.
The can then is placed in a retort and subjected to a temperature o 250~ F.
and a pressure of 15 psig or about 60 minutes. The abllity Oe a retorted product to maintain its structural integrity and bite characteristics can be tested by placing the product bet~,veen the thumb and forefinger and subjecting the product to shear forces. ~ retort stable prod~ct will not disintegrate with moderate finger pressure. A product with poor r etort stability will ~eel mushy and will fall apart when sub3ected to ~ derate shear orces, I Protein material employed in l;he process oE the present invention should contain at least about 40% protein on a dry weight basis. Of primary -iinterest are vegetable protein materials derived from soy~iean. Soy proteins - can take the form oE soy flour, soy conce~trate, soy isolates or mixtures thereo. The process oE the present invenhon is especially well suited to texturizing low protein materials swch as soy flour. Other oilseed -materials such as peanut, cottonseedJ and sesame seed may also be employed. Other known protein materials such as those derived Erom wheat, milk~ egg, single cell or leaf proteins and the like may be texturized according to the process of the present invention. Protein material 1~ employed should be viable9 i. e., have a PDI (Protein Dispersability Index~
25 lli in the range of from about 40 to about 90%~
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. : , . , . .. , .: . , ~, ¦~ Other protein sources suitable ~or the practice oî the present ¦! invention include natural meat proclucts. When texturizing meat proteins, the starting material employed should consist of a mi~sture o~ meat and a protein binder. Meat proteins may comprise meat scraps or pieces possessin~ poor textural qualities such as mechanically deboned chicken, beef, seafood, etc. or blends oE the ~oregoing. Suitable protein binders include vegetable proteins such as soy protein or other known proteins such as those derived fromwh'eat, yeast, milk~ egg, etc. In general, mixtures containing up to about 80% comminuted meat may be texturized according to 10 the process oE the present invention.
In accordance wlth the preEerred embodiment o~ the process of the ¦ present invention the protein material described' above is Eirst mixed with water to ~orm a protein dough or paste containing from about 60 to about 73% solids. I'his pasty or dowgh-like mixture then is advanced in a passive screw feeding means. In this ~eed ~one the produc~ may be preheated to a relatively low temperature in the range of about 110 up to about 150~ F.
It will be recognized that this is a temperature below which texturization will occur. The screw ~eed should be of the low work type which serves mainly to advance the protein dough rather thar~ subjecting it to severe 20 physical working, and typically is operated at less than 50 RPM's and pre~erably between about 8 to 12 RPMIs.
Protein dough ~rom the screw ~eed chamber then is rorced under I pressure through an extrusion die assembly which ~orms the protein into Il~ a thin sheet--like product. Applicants have ~ound that an extruded protein

2 5 1¦ product will possess hetter overall textural qualities i~ a unidirection~l li . .
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laminar tcxturiæat;on is imparted to both suraces of the pxotein sheek while ¦¦ it is still in the die assembly. SurEace texturi~ation of the protein sheet ¦¦ while it is still in the die assembly has been ~ound to build in certain unique Il textural characteristics to the protein structure such as retort stability, greater density and Eirmer bite identity.
SurEace texturizcltion as used herein is accomplished by appiyin~
external heat to both surfaces of the thin protein sheet aE: it passes through the die assembly. ~s the protein sileet passes through the die~ it should contact the heated die surEaces Eor a tirne suE~icienl: to texturize the surfaces of the protein sheet. The residence time in the die an be controlled by varying the product feed rate and/or by increasing the length of the die assemblyO Generally, residence times oE from about 0. 3 minutes up to about 1 minute or more are satis~actory to achieve the requisite degree ` o~ surEace texturization. I'he preferred residence time is about 0, 5 minutes,The upper limit vn die residence time should be less than the time at which ¦ thermal degradation begins. I)ie lengths of 6 inches or more have been satisfactorily employed in the process of the present invention.
The protein sheet formed in $he die should be relative~sr thm to achieve the overall enhanced properties oE the present invention. Satis factory results have been achieved with sheet thickness of up to about 1i 2 ¦ inch. The preEerred sheet thicl~ness is ahout 3/16 inch. The sheet thickness~
¦ should nol; be so great as to have a significant adverse eEEect on the final product.
~1 As used herein, the term "sheet" is intended to include (1~ a Elat 2 5 1! product with leng~h and width dimensions much greater than its thicknes~

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e a sheet oE paperJ and (2) a product in which a sheet as defined above is not all in one plane, e, g. J a tubular sheet Eormed Erom a flat sheet as in ? When reEerring to l'both" sides or surEaces oE a tubular sheet, the inner and outer surEaces are intended.
In the preferred embodiment the die assembly produces a thin tubular sheet oE protein. The te.rm "tubul'ar" as wsed througrhout the speciEication and clairns reEer's to shapes other than cylindrical tubes, such as square or triangular tubes. In the p.referred embodimen-t, however, the tubular extrudate forms a right circular c~linder of protein dough.
~ 3~trusion pressures developed at the orifice in the range oE about 1000 to about 1400 psi are suitable in the practice of the present inventio.n..
The temperatures developed at the extrusion dle are generally in the range of Erom about 150 to about 320~ F.
The thin protein sheet having the above described textured surface is extruded directly into a confined treating zone. :tn this treating zone, the protein texturization is completed by the action of heat and pressure from a ~lowing gaseous steam. This Eurther texturization is accomplished by' directing a heate~ gaseous stream at the thin protein sheet as ;t enters the conEned zone. The gaseous stream is directed at the protein sheel; in such a way as to cauee shear forces to develop in the sheet whereby a leading segment oE the continuous sheet is broken ofr and passes l:hrough the remainder of the confined treating zone. The Eorces necessary to break oEE any given segment of the sheet may vary with the degree oE turbulence and other EactorsJ and the:refore, the continuous extruded sheet is sheared o~E by the gas stream into segments oE varying lengths.

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` 11.- . `, , . i The surface texture bwilt int~ the protein sheet in ~he die assembly ~¦ also plays an important role in this gas shearing step. Since surface texturization greatly strengthens the shee-t product, greater shear forccs are needed to break off the leading segment As a result of the ti~ne it takes for these forces to d~velop, the intact extrùded she~t is retained in the Elowin~ stream of heated gas in thè confined zone for c~m extended period o time, e. g., Eor up to a minute or more. During this period beEore the protein segment is sheared oE, the flowing gas is extremely effective to impart textured qualities to the protein product. Moreover~ this holding period allows a high degree oE texturir~ation to be achieved without employing an extremely long conEined treating ~one, When the thin extruded sheet oE protein is tubular in shape, it is ¦ preîerred to longitudinally slit the tube into a plurality o~ indi~idual arcuate sheets as the tube leaYes ~e die assembly. Each o these arcuate sheets then is subjected to the gas low and broken oEf in the manner described above.
In the preEerred embodiment the gaseous medium is high pressure steam. Generally, arly steam pressure h;gh enough to shear of a portion o protein sheet may be employed. In practice, it has been Çound tha~
pressures of about 80 to 150 psi are suitable to accomplish this result.
Best results are achieved when employing pressures in the range o Erom about l:lO to about 120 psi.
~ny manner of steam injection which results in an impinging Elow oE steam at the surEace o the protein sheets may be utilized. Prererably, 1~ th~e steam is injected coaxially into the tubular sheet.

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.1 , After the cliscrete segments of textured proteirl breal; olf from the ~¦ semi-rigid sheet, the gas stream propels the segments through the conEined treating zone. In this confined treating s.one the elevated temperature, presswre ancl turbulence oE the gas Elow imparts ~urther texture to the protein pieces and volatilizes objectiona~le ~lavor cornpounds.
Generally, temperature~; in this confined treatment zone of up to about 350 F.
are suitable to achieve texturization with best results achieved in the range ' oE 310 to 35U F. Pressure in the conEined treatment zone is regulated by a back pressure maintaining means at the discharge end oE the conEined zone, Back pressures of up to about 100 psi measured at the exit port.~ should be mamtained in the zone. PreEerabb, the back pressure is l~ept in the range oE 60 to 80 psi. After passing through the back pressure maintaining means ¦ the protein segments can be recovered in any known manner. - , ~ One embodiment of the apparatus oE,the presen-t invention ~w will ~ be described by reeerence to Figure 1. A mixture of protein to be texturized and water is formed in any suitable mi~ing means (not shown).
The dough-like mixture Erom the mixing means is discharged into a screw feed chamber 2. The screw Eeed chamber ma~ be unheated over most oE its lengl~ and serves only to forward the dough to the extrusion die,. ~s the protein dough nears the extrusion die some external heat may be applied by steam or hot water jackets 3 or the like.
Communicating with the screw feed chamber is an elongated die l assembly 4 which is eEfective to extrude a continuous thin sheet oE

i semi-rigid protein dough. Ithe die assembly of the preEerred embodiment 1 comprises two concentrically disposed cylindrical surfaces dcEining a '', , I

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tubul~r extrusion orifice. 'rhe product produce(l by such a dic assembly ~¦ is a continuous tube of protein materialO ~s indicated ahove, the pre~erred shape oE the extrusion orifice deEined by the die assembly is a right ~, circular c~Tlinder, al~hc>ugh other shapes ~nay be employed.
1 In order to achieve a prodllct with high textural qualities the die ! assembly should be equipped with provision ïor supplying external heat to both sides oE the protein sheet. This externally supplied heat can take the Eorm of steam jackets 5. When the extrudate is a tubular sheet, heat must be applied to both the inner and outer surEace. The r equislte degree of texturization is not achieved when only one side oE the sheet is heated.
As the thin tubular sheet leaves the die assembly, it is longitudinally sliced into a plurality oE continuous arcuate sheets by slitting mear~ 6, as best shown in Figure 2.
I Communicating with the die/slitter assembly is a confined treating l zone 7~ ~s the protein sheets enter this treating zone, a stream oE heatedgas IS directed at them by an injeotion means. This preEerably is accomplished by the use oE a coaxial steam supply line 8 which d~Dlivers high pressure steam to the inside oE the tubular sheet.
In the confined treating zone 7 the protein material is subjected to the action o heat and pressure from the twrbulent gas ~low. PreEerably, this confined treatment zone takes the Eorm of an elongated tube or chamber, I The dimensions of this tube are not critical. In practice, tube lengths oEl about eight to ten Eeet generally provide suitable retention times although I longer or shorter tubes may be employed satisEactorily.
l At the discharge end o~ the con~ined treating zone is a back pressure I maintaining means 9. This back pressure xneans can comprise, ~or ,,, l ~

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`, e~ample, a spring loaded valve, a rotar~ valve, or a rotary letdown pump.In general, any device which allows the pro~3uct to e~it the conEined zone while maintaining a back pressure upstr earn may be employed. Suitable back pressure devices in the rotary letdown pump category incllltle the C P-6 ¦ made by Crearnery Package Co., Inc., and the Moclel R2 4PB Foster Food Pump made by 3~oster Pump Works, Inc. 'rhe product issuing from the l~ack pressure valve may be subjected to recovery by any 3~nown means. Since the product is essentially dry, it is only necessary to forward the steam protein mixture to a ~one where the steam can be ventecl off.
The product produced by the process of the present invention comprises sheet-like segments Or protein mateIial having structural and eating properties similar to animal meat produc~s.
l This product consists of two discrete regions. A cross section of a¦ portion of the extruded protein sheet of the present invention is shown in the ¦ photomicrograph o~ Figure 3. At the surface o~ the sheet, shown at the right of the picture, is a layer of dense ibrous protein material o:riented in one direction. This surface orientation is achieved by the special ~urface texturizing perFormed in the extrusion die according to the present invention, The interior portion of the sheet-li3se product of the preserlt invention is a dense protein matrix containing an open spherical cell development.
The interior porous structure o~ this product is best shown in the ¦¦ series of photomicrographs in Figure 4. This unique system of spherical voids surrounded by Q dense fibrous matrix provides randomly spaced ll shear points which give way upon chewing to provide bite and mouth feel ¦~ characteristics which simulate natural meat products. I
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The lalninar surface texturir~ation of the product of the present ¦l invention is best sho~vn in the series of photomicrographs which rnake up ~i Figure 5. This dense fibrous skin is formed on both sides of the product ~¦ where the sheet touches the heatecl die surfaces, ¦ By way of contrast, the product produced by the prior ar-t extrusion cooking process described above is showri in Figure 6. This product exhibits a structure comprising layers of protein separ ated by ~n elongated oval void system. Note also that the matrix is not very dense.
Furthermore.. the product of the present invention is Eree from objectionable elavor notes which in themselves often made prior art products unacceptable to humans. The severe working, temperature, and pressure ¦ conditions present in the prior art e~trusion cooking processes are believed ¦ to ~enerate certain oE flavors not produced in the r elatively passive treatment Oe the present invention.
¦¦ The severe condihons oE the prior art processes are also believed ¦ to adversely afEect the color and nutritional value of the finished product.
¦ The pxoduct produced according to the present invention possesses excellent ¦ color and nutritional stability. Another advantage achieved by ~e process and apparatus ot the present invention lies in the retort sta~ility o~ the product. Due to the unique structure imparted by the combination of surface texturi7ing in the die Eollowed by steam texturizing in the confined zone, the protein product Eormed in accordance with this invention may be j processed by conventional food preparation techniques without thernnal I degradation oE Its physical or organoleptic properties.
~1 Prod~lcts produced by the process oE the present invention ~ind ',1 utility in a number o~ ~ood processing fields~ These textllrized protein , . . .

products may be cut into portions sui-table for direct incorporation into li carlned or frozen foods. The texturized product may also be employed as li a Eiller or extender in ground meat products. It is also possible to produce ~ - ~abricate~ nutrients Erorn the protein material produced according to the ¦ present invention.
¦ The process oE the present inventlon is also useful to pro~7;de upgraded or restructured natural meat products, Meat scraps or by-products with little or no ood value (due to their poor struc-tural characteristics) can be texturizecl according to the process c) the present invention to provide chic~en, crabmeat, etc. cubes with good texture and mouth ~eel, The following specific examples are intended to illustrate more I ully the nature o the present invention without acting as a limitation on ¦~ its scope.
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l 5 E~MPLE 1 ~ textured soy protein material is produced according to the B present invention from soy 1Our. The starting material, Soy Flour 200W
~a soy 1Our produced by Central Soya, Inc. having about 50% protein) is mixed with water to orm a dough-like mixture having about 70% solids, This dough-like ~laterial is texturized in the apparatus shown in :F`igure 1, except that~ a longitudinal slitter was not employed, The extruder ~screw feeding means) is a Derancisci Model L.A.B
2VSM, The ~ie is a Cannelloni die which has been modified by providing ~ for steam injection in the center area~ and by lengthening the die to ~ inches, 25 ' The die Eorms a con-tinuous tubular sheet of protein urhich is ~bout ¦, ~ tr~de n,.al~<s ~, i l ~

1 3/16 inches ID and 3/16 inch thick. Surrounding the die is a conccntric ¦ steam jacket. The stearn supply to the center of the die is 110 to 115 psi.
¦ ~rom the clie the product is extruded into a 7 ~eet long cooking tube which is2 inches in diameter and equipped with a Model C-P 6 rotary letdown purnp made by Creamery Package Co., Inc. l'he bacl~ p:r essure in the coolcing tube is 76 to 84 psi and the cooking tube temperature~ is about 315 to 330 :F'.¦ The product recovered Erom the back pressure pump varies Erom small ¦ pieces to sheets approximately 3 x 8 inches~ This product is collected and dried and then subjectecl to retort processing. The retorted product exhibits excellent texture and mouth ~eel properties and has good clean odor and flavor.

E~MPLI~ 2 ., .
~ textured soy protein material is produced from a 70% solids dough oE soy flour as in Example 1, except that the longitudinal slitting means shown in :Figure 2 are employed. The extruder drive is run at 8 RPM and the extrusion pressure, at the die, is 1100 -~ 50 psi. The steam supply is 110 psi and a back pressure oE 70 -~ 5 psi and a temperature of 310 F, are maintained in the coo3~ing tube. The product~ similar to that produced in Example 1J exhibits excellent te~{tural charactelistics.

E~MPLE 3 This example demonstrates the importance oE applying external heat to the protein as it is being extrucled to impart surface texturization to the extruded product. The apparatus oE Figure 1 is modified hy employing an unheated clie and supplying the cooking tube steam Erom a T aEter the die ' ~
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~¦ rathe,r than coaxially within the die. In other respects, the starting ¦1, materials and process parameters are as in Examplt,~ 1. rrhe product produced does not have the characteristic texturi~ed skirl of' the product of the present invention. Although this product appears to have satis-factory texture as produce~d, upon retort processing the product completel~
loses its texture and has no integri-ty when handled. The re-toxted product appears to have more gel properties than tex-turecl properties.
While certain specific ernbodiments o~ the invention have been described with particularity herein, it should be recognized that various 10 ~ modificat;ons thereof will occur to those sl~illed in the art. Therefore,the scope of the invention is to be limited solely by the scope o~ the claims appended h reto.

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Claims (28)

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

1. A method for producing a relatively dense texturized protein product with a unidirectional laminated surface structure comprising:
(a) mixing untextured protein material and water to form a protein dough, said dough containing from about 60 to about 73% solids;
(b) advancing said dough to a die means at a temperature below that at which texturization takes places;
(c) continuously extruding a relatively thin sheet of semi-rigid protein material through said die means while simultaneously texturizing both surfaces of said thin sheet as it passes through said die means by externally applying heat to both surfaces of said sheet;
(d) passing said extruded sheet directly into a confined treating zone while simultaneously direc-ting a heated gaseous stream at said extruded sheet as it enters said confined treating zone to break off the leading segment of said extruded sheet, said gaseous stream further propelling said segments through said confined treatment zone;
(e) passing said protein segments through a back pressure maintaining means disposed at the discharge end of said confined treating zone; and (f) recovering the texturized protein segments.

2. The method of claim 1 wherein said protein material comprises at least about 40% protein on a solids basis.

3. The method of claim 1 wherein said protein material comprises soy flour having a protein content of about 50% on a solids basis.

4. The method of claim 1 wherein said protein dough is advanced to said die means by a low-work screw feeder.

5. The method of claim 4 wherein said protein dough is preheated to a temperature in the range of about 110 up to about 150°F in said screw feeder.

6. The method of claim 1 wherein said externally applied heat is supplied by steam jackets.

7. The method of claim 1 wherein said thin sheet of protein material is heated to a temperature of from about 150°F to about 320°F as it is being extruded.

8. The method of claim 1 wherein said thin sheet of protein material is extruded at a pressure of about 1000 to 1400 psi.

9. The method of claim 1 wherein said extruded thin sheet is tubular in shape and further comprising the step of longitudinally slitting said tubular sheet into a plurality of continuous arcuate sheets as said tubular sheet enters said confined treatment zone.

10. The method of claim 9 wherein said tubular sheet comprises a right circular cylinder.

11. The method of claim 1 wherein said gaseous stream is steam.

12. The method of claim 11 wherein said steam is directed at said thin sheet at a pressure of from about 80 to about 150 psi.

13. The method of claim 11 wherein said steam is directed at said thin sheet at a pressure of about 110 to about 120 psi.

14. The method of claim 1 wherein said confined treating zone is maintained at a temperature of about 310 to 350°F.

15. The method of claim 1 wherein said confined treating zone is maintained at a temperature of 310°F.

16. The method of claim 1 wherein said confined treating zone is maintained at from about 60 to about 80 psi.

17. The method of claim 1 wherein said extruded thin sheet of semi-rigid protein material retains its integrity for a short distance into said confined treatment zone before the shear forces created by said gaseous stream reach sufficient strength to break off said leading segment, whereby said sheet is subjected to the conditions in said confined zone for an extended period of time.

18. Apparatus for texturizing protein material comprising:
(a) die means for extruding a continuous, relatively thin sheet of semi-rigid protein material;
(b) means for externally applying heat to both surfaces of said thin sheet as it passes through said die means to effect surface texturization of said thin sheet;
(c) means defining a confined treating zone communicating with said die means;
(d) means for directing a heated gaseous stream at said extruded thin sheet as it enters said confined zone to break off the leading segment of said extruded sheet; and (e) means for recovering said texturized protein material.

19. The apparatus of claim 18 additionally compri-sing low-work screw feed means communicating with said die means.

20. The apparatus of claim 18 wherein said die means defines a tubular shaped orifice, said apparatus further comprising means for longitudinally slitting an extruded tubular sheet into a plurality of continuous arcuate sheets, said slitting means disposed at the entrance to said confined zone.

21. The apparatus of claim 20 wherein said die means comprises two concentric cylindrical shaped surfaces defining a right circular cylindrical orifice.

22. The apparatus of claim 21 wherein said means for directing a heated gaseous stream is coaxially disposed within said die means.

23. The apparatus of claim 18 additionally com-prising back pressure maintaining means disposed at the discharge end of said confined zone.

24. Apparatus for texturizing protein material comprising:
(a) means for mixing a source of protein and water to form a protein dough;

(b) means for advancing dough without imparting excessive work to said dough;
(c) die means for extruding said dough in the form of a continuous relatively thin sheet of semi-rigid protein material;
(d) means for externally applying heat to both surfaces of said thin sheet as it passes through said die means to effect surface texturization of said thin sheet;
(e) means defining a confined treating zone communicating with said die means;
(f) means for directing a heated gaseous stream at said thin sheet of protein material as it enters sad confined zone to break off the leading segment of said extruded sheet;
(g) back pressure maintaining means disposed at the discharge end of said confined zone, said back pressure means maintaining a predetermined back pressure in said confined zone; and (h) means for recovering said texturized protein material.

25. The apparatus of claim 24 wherein said advancing means comprises a low-work screw feeder.

26. The apparatus of claim 24 wherein said die means defines a tubular shaped orifice, said apparatus further comprising means for longitudinally slitting an extruded tubular sheet into a plurality of continuous arcuate sheets, said slitting means disposed at the entrance to said confined zone.

27. The apparatus of claim 26 wherein said die means comprises two concentric cylindrical shaped sur-faces defining a right circular cylindrical orifice.

28. The apparatus of claim 27 wherein said means for directing a heated gaseous stream is coaxially disposed within said die means.