CA1046337A - Dried protein product of improved emulsification properties and flavor - Google Patents

Abstract

A DRIED PROTEIN PRODUCT OF IMPROVED
EMULSIFICATION PROPERTIES AND FLAVOR
Abstract of the Disclosure A process for the production of a dried soy protein product of improved emulsification properties having a substan-tially bland flavor is disclosed which comprises; forming a slurry of isolated soy protein having a pH of between about 5.7 to 7.5 and a solids content within the range ofr 5 to 17%, and dynamically heating the slurry under a positive pressure, after which undesirable flavors are removed by causing instant pressure release to flash off excess moisture laden with the undesirable flavor components. The addition of an edible reducing agent in an amount of at least about 0.1% by weight of the solids is included either before or after the deflavorization step and the drying temperature is controlled to a critical temperature of below about 200°F. to provide the protein product with improved emulsification properties.

Description

104~337 Background of the Invention The present invention relates to a dried proteln product of lmproved emulsiflcation properties and flavor.
Isolated protein which is derived from vegetable protein sources such as soybean meal has been determined to possess a wide degree of functlonallty in various food products.
One application for this material has been in the preparation Or ground meat products. The isola~ted soy protein or ~lour has been used in these ground meat products as a fat emulsifier and water binding agent. Normally, however, the relative percentages o~ ~at and molsture ls so hlgh in ground meat products that a hlgh percentage Or protein material must be ~;
used to ~orm a stable emulsion with the ~at and water. By the same token, the use of a higher percentage o~ soybean flour lmparts an undesirable flavor to the meat product because Or the "beany" ~lavor that ls characteristic of soybeans. For thls reason, sodlum caseinate or proteln sources derived ~rom materials other than soybeans have been employed to overcome the ~lavor problem assoclated with soybean blnders ln ground meat products. However, while the flavor problem ls overcome, casein ls relatively ine~fective in providing a stable emulsion.
This is readily illustrated by a cooking test in which an emul-slon Or ~at, water and protein is ~ormed, after which it is oanned and retorted at 245F. under pressure to coagulate the proteln. The emulsion can be removed as an integral mass, a~ter which lt is cooked in a hot skillet and the ~at and molsture loss measured. Usually, emulsions prepared with sodium caselnate as a blnder wlll completely melt or dislnte-grate upon cooking.
United States Patent 2,881,076 descrlbes a soy protein composition and method for its production includin~ its use as

- 2 -- . ~. .

an emulslfler for fat and water. This protein composition, of desirable emulsification properties is produced by heating the aqueous mass of protein at a pH above 6 at a temperature of 100 to 180F. to render the protein more colloidal or gel-like.
The solids suspension, after heat treatment is then dried to rorm a ~owder useful as a binder for ground meat. While the emulsification properties of the soy protein is enhanced by thls treatment, nevertheless protein products produced by this process still suffer from the above descrlbed deficlency with regard to flavor.
The flavor of isolated protein derived from soybeans has been significantly improved by processing techniques such as described in United States Patent 3,642,490. The process descrlbed in this patent relates to controlled dynamic heating o~ an aqueous slurry of the soy protein to an elevated temper-ature range followed by physlcal working of the slurry under dynamic condltions and under controlled posltive pressure. The slurry i5 retained for a brief period of time under these con-dltions after which the undesirable flavors are removed by causing subsequent lnstant pressure release to cause flash off, wlth vaporizatlon of some of the moisture that is laden with these undeslrable flavor components. The slurry ls then dried to a white powder of a substantlally bland flavor. Whlle the product is markedly improved in flavor, nevertheless, lt ls not as deslrable as a binder for ground meat products. Further processlng ls requlred to produce a product suitable as emulsifier for fat and water mlxtures which is of the same quallty o~ blandness as this product but which has superior emulsifying properties.
It ls therefore an ob~ect o~ the instant invention to produce a soybean protein product with a bland flavor having improved emulsification properties.

It is also an object of the instant invention to provide a process for the production of a protein isolate which signific-antly enhances its emulsifying properties while retaining a substantially bland flavour.
It is a further object of the instant invention to provide a process for the production of such a product that is economical and commercially feasible to produce.
It is another object to provide a protein product that will effectively bind fat and water emulsion even when the emulsion is subjected to cooking.

Summary of the Invention The emulsification properties of a dried soy protein isolate having improved flavor characteristics has been markedly improved by the addition of an edible reducing agent to the aqueous protein slurry either before or subsequent to the dynamic heating step together with critical control of the drying temp-erature of the isolate to below about 200F. The instant process for the production of a soy protein isolate having these propert-ies therefor includes, in one aspect, the process for the prod-uction of a dried protein isolate of improved emulsificationproperties and flavor comprising: forming a slurry of isolated 90y protein having a ph of about 5.7 to 7.5, dynamically heating said slurry under a positive pressure at a temperature above about 175F, retaining the heated slurry under a positive pressure for at least a few seconds, releasing the pressure to cause flash off volatilization and removal of moisture laden with undesirable flavor components, adding to the slurry an edible reducing agent in an amount of at least about 0.1% by weight of the solids in the slurry to improve the emulsification properties of the soy protein, and drying the slurry at a temperature below about 200F. to produce a dried protein isolate. AlthoUgh in the previous production the edible reducing agent is added subsequent to the heating step, it may be added prior to the heatlng step ~ - 4 -~' ~ 04a"~37 to also alter the properties of the protein isolate and as a consequence improve its emulsification properties.
Althouyh not limiting, it is theorized that an en-hancement in emulsification properties of the isolate 4 a -~t ~ 04~;;337 is achi~ved by a change in the svlubility characterlstlcs Or the isolate because of the processing techniques. This results in the productlon Or an lsolate that is a better emulsirler because Or the colloidal nature Or the dried protein particles. This change in the physlcal characteristics Or the particl s ls belleved to be due to the effect Or the reduclng agent and drying temperature on the rate of hydration Or the drled soy protein. The edl~le reduclng agent can be added to the slurry immediately prior to the dynamic heating step or subsequent to it. Following deflavorization, a drled protein isolate is produced by drying of the protein slurry.
It has been determined that lr critlcal control Or the drylng temperature ls maintained together with the addition of a reducing agent~ the emulsiflcation propertles Or the dr~cd product are further lmproved. In thls regard, lt has becn detcrnlincd that it ls necessary to control the drying temperature to below about 200F. and preferably between 165 and 200F. When the temperature ls permitted to exceed 200F., the rate of hydration Or the dried proteln product and hence its emulslrlcation properties are less deslrable.
It has also been determined in con~unctlon with the sbove that the addition Or an edible reducing agent is necessary to achieve an improvement in emulsificatlon properties Or the protein, wlth the amount Or addltion belng at least about 0.1%
by weight Or the solids, with a prererred range of 0.1 to 2.0 by weight of the solids. The mlnimum percenta~e Or reducing a~ent is necessary to change the emulsirication propcrties of the protein while the upper limit is determined slmply by the need to avoid another flavor problem, this one associated with a hlgh level Or reducin~ agent used to alter the physlcal Gharacterlstlcs of the proteln.

E~

When emulsions of fat and water are prepared with the protein isolate of the instant invention, canned and retorted to coagulate the protein, the resultant products when fried show less than 50Z Or the fat 105S which characterizes the same product without the addition of reducing agent. The isolate, however, st~ll possess~s the highly desirable bland flavor characteristics of the isolate which has employed a dynamic heating step to~deflavorize the pro-telnaceous slurry.
Description of the Preferred Embodiments In a brief outline Or the total process, the soy-beans forming the starting material are ground or crushed, the oil extracted to leave soybean meal or flakes, the pro-telns and sugars are dissolved out of the flakes into solution, the proteins are precipitated, washed and put into water sus-pension as a slurry. The slurry is ad~usted to a controlled pH range as described in detail hereinafter. The slurry also has a controlled range of solids. The slurry is thereafter deflavorized by a dynamic heating step employing positive pressure and "flash off" or release of pressure to volatllize entrapped flavors ln the protein. Prior to or subsequent to deflavorization, an edible reduclng agent is added to the slurry in a critically controlled amount to improve the emulsi-ficatlon properties of the protein followed by drying of the product at a temperature below about 200F.
More specifically, the soybeans are crushed or ground in convenient fashion. The oil is preferably removed by solvent extraction, using solvents normally employed for this purpose.
The resulting sollds, commonly referred to as soy-bean meal, and normally in the form of flakes, contain many ~04~37 lngred~ents including complex proteins, sugars, fibers, and others. The proteins and sugars are then preferably dissolved out Or the bath by adding a food grade al~aline mater~al to ralse the pH to 7 or above. Typical of such alkaline reagents i8 sodium hydroxide, potassium hydroxide, calcium hydroxide or other commonly accepted food grade alkaline reagents. The material is then extracted ror a period of time surficient to put the proteins and sugars in solution, usually about 30 minutes or so. The resulting liquor solution is separated ~rom the solids, as by passing the material through a screen and/or centrifuging. Preferably, the liquor is then cycled through a claririer to remove tlny particles.
It may ~urther be desirable to include other chemical reagents in the protein slurry during alkaline extraction lncluded among which are the sulfite salts and these modlfications o~ the alkaline extraction procedure are to be included within the scope of the present invention. Insofar as the addition Or sulrite ~ or similar reducing agent during extraction, most Or this is removed during the protein isolation process so the addition of the described percentage of reducing agent either berore or after deflavorization is still necessary to improve emulslfication of the protein, even if sulrite is added during the alkaline extraction step.
The soy proteins are then precipitated from the liquor by lowering the pH to an acidic value of the isoelectric point Or the protein, usually a pH Or 4.6 - 4.9, with the addition Or a common food grade acidic reagent such as acetic acid, phosphoric acid, citric acid, or others. The preclpitate is then separated as by centrlfuglng, and washed wlth water to remove remaining sugars, except for a minute trace which is practically impossible to remove. The aqueous slurry of the ~ O~ ;37 preclpltated protein is diluted by adding water.
The slurry then has its pH ad~usted, specifically, the pH ls ad~usted to a range of about 5.7 to 7.5, preferably between about 6.5 and 7.2. Below about 5.7, the water dlspersibility of the final product is very low and not useful for many purposes. At a pH above about 7.5 and approaching 8.0, the final product tends to assume an undesirable soapy taste.
The degree of disperslbillty in the flnal product can be regu-lated by varylng the pH wlthln the controlled pH range of about 5.7 - 7.5, to sult the product to the final food being prepared.
The pH may be easily adJusted by adding a ~ood grade alkaline reagent such as sodium bicarbonate, or an alkaline earth metal hydroxlde.
The slurry to be further processed should have a controlled solids content of about 3 - 30% by welght, and pre-ferably about 5 - 17% by weight. If lt falls below about 3%, subsequent processlng steps are not econom~cally advlsable when a contlnuous process is employed. Drying is particularly costly.
Above about 17% sollds content, the resultlng product does not subsequently lend itself to the preferred flash drylng tech-niques, such as spray drying using a ~et or spinning thrower or such, so that other drying techniques must be employed, to result in a product that is not as desirable in its functional ¢haracteristics.
The aqueous slurry of soybean protein materlal may be then sub~ected to dynamic heating pursuant to the deflavorization procedure as hereinafter described, after which reducing agent additlon can be carried out, or alternatively the reducing agent can be added be~ore the de~lavorizatlon procedure. In either situation the reducing agent is added in an amount of at least about 0.1% based on the weight of solids in the slurry, with a ~ 04~;337 preferred level of addition being between 0.1 and 2.0% by weight Or solids.
The edible reducing agent may be selected from a varlety Or materials including sulfur dioxide, sulrurous acid or salts thereof such as the sulfites and bisulfites, or salts Or phos~horous acid such as the phosphites. Typlcal salts of choice include the alkaline earth salts such as sodium and potassium. The present invention is not intended to be limited by the particular type Or edible reducing agent that may be employed, provided that the source is capable Or ionization in an aqueous system to yield a reducing component to improve the rate of hydratlon of the protein.
The de~lavorizatlon process Or the present invention ls that disclosed in United States Patent 3,642,490 which comprises sub~ecting the aqueous slurry to dynamic heating under positive pressure, followed by "flash off" or volatilization of a portlon o~ the moisture by e~ection of the pressurlzed slurry lnto a vacuum chamber or area Or negative pressure. In this manner entrapped flavor components are readily removed. The positive pressure can be created in the aqueous suspension ltself by direct steam in~ection into the slurry and conrinement Or the slurry, or the slurry can simply be conrined and the temperature elevated without direct steam in~ection.
The application Or positlve pressure, sub~ects the slurry to dynamic working while at this elevated temperature range. Currently, a typical but nonlimiting apparatus used to achieve this is a de~ice known as a ~et Cooker. It includes ad~acent ~et nozzle orifices, normally concentric, through which the slurry and the pressurized steam used as a heating agent are e~ected at high veloclties in intersecting flow patterns, so that each tiny bit of slurry ls instantly dynamlcally 3j~37 heated by the steam while practically simultaneously being sub~ected to severe physical forces at the nozzle, such physical workln~ being largely of a shearing nature. The physical working of each tlny portion is believed to expose the obnoxious sub-stances to further action, and this physical working with the elevateæ temperature heat treatment is believed to weaken and/or break the tenacious bond between these obvious substances and the complex protein molecules, to an extent where these substances can be laded away by flashed orf vapors, as described hereinafter. Thls physical working and heating also tends to eliminate some Or the characteristic soy flavor, but more importantly, prepares the material for the subsequent processing steps. The temperature range to which the slurry is heated for the desired results is about 175 - 400F., although the tempera-ture should not be in the lower region of this range unless the product is subsequently vented into a vacuum chamber after being held under pressure in a special holding chamber, as explained herelnafter. Normally,the temperature should be about 285 - 320F. for best results.
The product is introduced to the Jet Cooker nozzle at a positlve pressure. Thls pre~.sure should be at a value near the pressure Or the steam in~ected into the slurry, should be sufficient to cause high-velocity discharge of the slurry through the ~et nozzle, and must be greater than the pressure in the special retention chamber lmmediately down-stream of the nozzle. Normally the steam pressure is about 80 - 8~ psig, the slurry line pressure is slightly above the steam pressure, usually about 85 - 100 pslg, and the dlscharge pressure ln the chamber downstream of the nozzle is about 6;5 - 80 pslg. The pressure drop of the slurry across the nozzle is about 5 - 15 psi, depending upon these other pressures, with 6 - 10 psi being common.

~04s~37 The time interval of thc slurry in the nozæle is estimated to be about 1 second or less. The nozzle ori~ice for the slurry is small, being only a fraction of an inch, e.g., about one-eighth lnch, so that t~le slurry sollds are sub~ected to severe dynamlc, physlcal working during passage. The steam intermi~es intimately wlth the solids in the e~ected slurry.
The amount of steam requlred is not great, normally being an amount to lower the solids content ~o~ the slurry about 1 - ~%
by weight. Preferably the nozzle orifices are concentric, with the slurry being eJected from the center orifice, for example, and the steam from a surrounding annular orifice oriented to cause its output ~low path to intersect the output flow path of the center orlfice. The slurry and steam could be e~ected rrom the alternate orifices however. Further, the ad~acent orifices need not necessarily be concentrlc to obtaln this interaction.
As noted prevlously, the steam and slurry are e~ected lnto a special retention chamber. This may comprise an elongated tube through which the lntermixed slurry and steam moves from the ~et nozzle on one end of the tube to a pressure controlled dlscharge on the other end. The discharge can be controlled by a conventional preset pressure release valve to enable con-tinuou~ process flow ~rom the nozzle to and o~t o~ the dlscharge valve. mis valve regulates the pressure in the holdlng chamber.
Thls chamber pressure must be great enough to prevent any slgni-~lcant vaporlzation Or the moisture in the chamber, even though the temperature is well above the boillng point of water. A
pressure of about 65 - 80 psig readily achleves this. Slnce slurry and steam must continuously ~low into this pressurized chamber, the pressure behind the slurry and the steam must be greater than the chamber pressure to cause this continuous flow.

~O~i~;337 The heated slurry ls retained in the holding ch~mber for a definite but relatively short period of a few seconds up to a ~ew minutes, normally Or about 7 seconds to about 100 seconds and preferably from about 3 to 20 seconds. It is only necessary to retain the product in this heated condition for a f~w seconds for optimum reiults. Therefore, the pa ticu-lar retention time is not deemed to be limlting insofar as the present invention.
The pressure on the slurry is then instantly released by dlscharging the slurry to a reduced pressure zone, into a suitable receiving means. This causes "flash off" of a portion of the moisture in the form of water vapor which is laden with the entrained odiferous chemical components or substances of unknown composition from the soy product. The flash off also causes substantial coollng of the remalning slurry because Or the heat o~ vaporlzation absorbed from the slurry, so that the total time which the product is sub~ected to elevated tem-peratures is very short and controlled. Removal of the substance-laden vapors removes the ob~ectionable ~lavor and odor components.
The reduced pressure zone into which the slurry is dlscharged is normally at atmospheric pressure, but it is sometimes subatmospheric, i.e. at a partial vacuum. In elther case, the vapors should be lnstantly conducted away from the slurry, preferably by a movlng current of air across the slurry or by drawing a continuous vacuum on the discharge zone to draw the vapors away. The vapors may be specially condensed in a fashion to positively remove the condensate from the area of the collected discharged slurry. In production, the slurry may be discharged from the back pressure control discharge valve directly into a vessel ln the open atmosphere where the vapors are allowed and/or caused to rise directly away from the , ~ 04~;337 slurry and are prevented rrom condensing in a manner to a:low the condensed substance to flow back into the product.
To assure complete removal of the vapors from the purifled slurry wlthout allowlng the vapors to recondense back lnto the slurry, the slurry and vapor should be separated immediately after dlscharge, l.e. lmmediately after pressure release. In thls regard lt ls ur.deslrable to cause passage of both components through a common conduit downstream of the discharge valve, and lf such is done, lt should be minlmal.
The aqueous slurry may then be dried to a powdery condltlon, and lt ls preferred to flash dry the product because of the unlform nature of the product obtalned. It has further been determined pursuant to the instant invention, that lf the drying temperature of the protein product is controlled to below about 200F. or preferably to between about 165 to 200F. that the emulsification properties of the dried protein material are further im~roved. It is theorized that this is due to the better hydration capacity of a proteln product dried at this temperature slnce when a temperature above about 200F. is used, the dried protein material does not hydrate as readlly. Of the flash drying techniques, spray drying is usually employed.
The lnstant invention is not intended to be limited by the particular drying technique employed and other techniques may be employed provided that the temperature is controlled as stated. The dried protein product is then suitable as an emulsl~ier fox water and fat systems as are ordinarlly found in ground meat emulslons or products such as sausage, frank-furters, etc. In determinlng the suitablllty o~ the lnstant product as an emulsl~ler for ground meat products it is common to employ the protein product in a test for emulsification properties as hereinafter described.

~4~;337 The protein product is combined with fat and water in respective weight ratios of 1 part protein to between about

3 to 9 parts of both fat and water. Typically, a weight ratio of 1 part proteln, 5 parts fat and 5 parts water is employed.
Thls mlxture is then homogenized to form an emulsion and placed ln a suitable container such as a can. The product is then cooked for between about 15 to 20 minutes at 230 to 250F. to coagulate the protein and form a substantially unsegregated mass of the emulsion. A portion of the emulsion is then taken and placed ln a frying pan and fried, after which the loss of water, and particularly fat due to cooking is measured. In this manner, the emulsification properties of the protein product may be evaluated, in that the loss of fat is directly associated with the emulsification propertles of the protein product. It is desirable of course to keep the loss of fat due to cooklng to a minimum.
The followlng Examples are set forth as speclflc embodlments Of the lnstant invention for illustratlve purposes.
Example 1 ? About 500 lbs. of solvent extracted soybean flakes were suspended in 5000 lbs. of water to which was added 1.8%
Or calcium hydroxide thereby raising the pH to about 10.5.
Additionally, 1.5% of sodium sulfite was added to the alkaline slurry. The mixture was held at 90F. and extracted for 30 mlnutes. Following extractlon, the undissolved solids and spent ~lakes were removed by centrifugation and resuspended in 600 lbs. of water. The resuspended mixture was again centrifuged and the spent flakes discarded. The original extract and that of the resuspended flakes were combined. The pH of the extract was lowered to about 4.5 wi~h phosphorlc acid to precipitate the protein. The water was removed from the precipitated protein by centrifugation and to the "curd" was added an equal volume of water for washing of it. After agita-tion, the water wash was removed by centri~ugation, thereby ylelding 615 lbs. of curd at 27.9% solids.
The 615 lbs. of curd was dispersed in 640 lbs. of water tc produce a solids level of 13.6% by weight, and the pH
of the slurry was ad~usted to 6.8. One hundred pounds of the slurry was then passed through a Jet Cooker. The steam heats the slurry through the Jet Cooker to a temperature of 310F.
The heated mixture is held under a posltive pressure for 10 seconds, after which it is discharged into a vacuum chamber held at a pressure of 20 inches of mercury. This causes flash off volatilization of moisture laden with undesirable flavors.
To a 50 lb. portion of the ~et cooked slurry was added 0.2%
sodium sulfite based on the weight of the sollds ln the slurry.
Thls sample was spray dried at a temperature of 18~F. to yield a desirable, whitlsh protein powder of a bland flavor.
Example 2 To a second 50 lb. portion of the ~et cooked slurry produced in Example 1 was added 0.4% sodium sulfite based on the weight Or solids in the slurry. This sample was spray dried at a temperature of 180F. to yield a whitish protein powder of a bland flavor.
xample 3 To a 75 lb. portion of the aqueous slurry prior to ~et cooking, as set forth in Example 1, having a pH of 6.8 and a solids content o~ 13.6%, was added 0.2% by weight of sodium sul~ite, based on the weight of solids in the slurry. The slurry, with added sulfite is then passed through a Jet Cooker, and the Jet Cooker ~s used to heat the slurry to a temperature of 310F.
The heated mixture is held under a positive pressure at this ~(J4~37 temperatlre for 10 seconds after which it is discharged lnto a vacuum chamber held at a pressure of 20 in. of mercury, at which time flash off volatilization of the flavor components takes place. The cooked slurry was then spray dried at 180F. to yield a whitish prote~n powder of a bland flavor.
Example 4 The spray dried protein products obtained from Examples 1, 2 and 3 were then comparatively tested against a spray dried quantity of ~et cooked product designated as the control which had been processed pursuant to Example 1 absent any addition of sulflte. The testing was designed to evaluate the relative emulsification properties of these protein products and were handled as follows:
Protein, fat and water emulsions were prepared by adding 150 grams of the proteln products from Examples 1 to 3, and the control of 500 ml. of water ln a food chopper and chopplng the mixture for 90 seconds. Three hundred fifty grams of pork fat back was then added, and the mixture was chopped for an addltional 3 1/2 minutes.
The four dlfferent emulsions were then placed in 7 oz.
cans and retorted at 250F. for 30 minutes. Following retorting, each emulsion was removed from the can, at which tlme it was observed that the emulsions produced pursuant to Examples 1 to 3 were excellent in quality with little visible separation of fat and water while the control showed a considerable separation of the fat.
At this time, each solidified emulsion was sliced in half, and each half portion from each emulsion having the following designated we~ght was separately placed in an electric skillet held at a temperature of 340F. and cooked on one side only for 10 minutes to determine fat and moisture loss ~04~;~3~7 on cooking for each portion. The results of this testing are set forth below in Table 1.
Table 1 Cooking (gm) Average % Weight Weight % %
SampleSulfite Before A~terCookout Cookout Example 1 0.2 89.3 85.2 4.6 4.7 84.3 80.3 4.7 Example 2 0.4 79.4 76.2 4.0 4.1 86.6 83.o 4.2 Example 3 0.2 72.0 70.0 2.8 3.1 85.2 82.3 3.4 Example 4 0 74.1 67.6 8.8 8.3 91.0 84.o 7.7 It may be seen from the data in Table 1 that the samples of proteln product pursuant to Examples 1 to 3 was significantly better than the control in emulsifying the mixture of fat and water, as evidenced by smaller cookout of the emulslons prepared wlth proteln product produced pursuant to the lnstant lnventlon.
Example 5 A portion of washed curd produced as set forth in Example 1 was ad~usted to a solids content of 13% by the .addltion of water and the pH ad~usted to 6.6. To the slurry was added 0. 3% sodium sulfite based on the sollds content and the mixture was then passed through a ~et cooker. The steam heated the slurry in the ~et cooker to a temperature of 310F.
The heated mixture was then retained under a positlve pressure ror 10 seconds, after whlch lt ls discharged ~nto a vacuum chamber to cause flash off volatillzation of undesirable flavors.
Followlng this, the mlxture was spray dried at 180F. to a whitish powder.
~ This proteln product was then comparatively evaluated agalnst the followlng products to determine its emulsiflcation properties as compared to these products. Sample 1 was the ~ (~4~37 protein product of thls Example, Sample 2 was sodium caseinate, a prlor art emulsifier, Sample 3 was a soy protein 70%
concentrate, unprocessed to remove residual flavor components, and Sample 4 was a protein product processed as described above to remove resldual flavors, but without the addition of sulfite.
One part by weight of each of the above samples was combined with 5 parts b~ weight of water, and 5 parts by weight of pork fat back and chopped in a food chopper for 5 mlnutes to form an emulsion.
Each emulsion from each sample was then placed in a 7 oz. can, sealed and retorted at 230F. for 30 minutes.
Following this, each emulsion was removed from the can and sliced in half. Each half portion o~ each sample, was then placed in an electric skillet held at a temperature of 340F.
and cooked on one side only for 10 minutes to measure fat and moisture loss during cooking. The results of this test are set rorth in Table 2.
Table 2 ~ _ , .
~ooking ~gm~ Average Weight Weight %
20Sample _ Before After Cookout Cookout 1 90.6 82.5 8.9 8.4 lol.l 93.2 7.8 2 87.2 Emulsion broke during cooking 85 .2 3 90.1 78.0 13.4 13.1 99.8 87.1 12.7

4 85.3 74.0 13.2 12.3 91.9 81.5 11.3 It may be seen from the above cooking data that the emulsion using sodium caseinate as a binder could not withstand the cooking test, ~nd the 70% soy protei~ concentrate had a much 30 higher cooking loss than the product of the lnstant inventlon.

It is further illustrated by the above data, that a protein product deflavorized as in the instant invention but wlthout the addltlon of reducing agent had a higher cooklng loss than the emulslon prepared with the protein product of the lnstant lnventlon. The proteln emulslon contalning the product of the instant invention was further ch~racterlzed by a very wh~te color and essentially bland flavor.
The above Examples are merely illustrative of the instant lnvention and lt will be understood that varlous other changes in the details, materlals or steps whlch have been descrlbed may be made wlthout departing from the spirlt of the instant disclosure, and such changes or modl~ications are intended to be included wlthln the scope of the lnstant disclosure and appended clalms.

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Claims (19)

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

1. A process for the production of a dried protein isolate of improved emulsification properties and flavor comprising:
a. forming a slurry of isolated soy protein having a pH of about 5.7 to 7.5;
b. dynamically heating said slurry under a posi-tive pressure at a temperature above about 175°F.;
c. retaining said heated slurry under a posi-tive pressure for at least a few seconds;
d. releasing said pressure to cause flash off volatilization and removal of moisture laden with undesirable flavor components;
e. adding to said slurry an edible reducing agent in an amount Or at least about 0.1% by weight of the solids in said slurry to improve the emulsification properties of the soy protein; and f. drying said slurry at a temperature below about 200°F. to produce a dried protein isolate.

2. A process as set forth in Claim 1 wherein said slurry has a solids content of between about 5 to 17% by weight.

3. A process as set forth in Claim 1 or 2 wherein said slurry has a pH of between about 6.5 to 7.2.

4. A process as set forth in Claim 1 wherein said edible reducing agent is a salt of sulfurous acid.

5. A process as set forth in Claim 1, 2 or 4 wherein said slurry is heated to a temperature of between about 285 to 320°F.

6. A process as set forth in Claim 1 wherein said slurry is retained under a positive pressure for between about 3 to 20 seconds.

7. A process as set forth in Claim 1 wherein said drying is carried out at a temperature of between about 165 and 200°F.

8. A process as set forth in Claim 1, 6 or 7 wherein said edible reducing agent is sodium sulfite.

9. A process for the production of a dried protein isolate of improved emulsification properties and flavor comprising:
a. forming a slurry of isolated soy protein having a pH of about 5.7 to 7.5;
b. adding to said slurry a sulfite reducing agent in an amount of at least about 0.1% by weight of the solids in said slurry to improve the emulsification properties of the soy protein;
c. dynamically heating the slurry under a positive pressure at a temperature above about 175°F.;
d. retaining said heated slurry under a positive pressure for at least a few seconds;
e. releasing said pressure to cause flash off volatilization and removal of moisture laden with undesirable flavor components; and f. drying said slurry at a temperature below about 200°F. to produce a dried protein isolate.

10. A process as set forth in Claim 9 wherein said slurry has a solids content of between about 5 to 17% by weight.

11. A process as set forth in Claim 9 wherein said slurry has a pH of between about 6.5 to 7.2.

12. A process as set forth in Claim 9 wherein the edible reducing agent is a salt of sulfurous acid.

13. A process as set forth in Claim 9, 11 or 12 where in the edible reducing agent is sodium sulfite.

14. A process as set forth in Claim 9, 10 or 11 where-in said slurry is heated to a temperature of between about 285 to 320°F.

15. A process as set forth in Claim 9 wherein said slurry is retained under a positive pressure for between about 3 to 20 seconds.

16. A process as set forth in Claim 9, 12 or 15 wherein said drying is carried out at a temperature of between about 165 and 200°F.

17. A process for the production of a dried protein isolate of improved emulsification properties and flavor comprising;
a. forming a slurry of isolated soy protein having a pH of about 6.5 to 7.2 and a solids content of about 5 to 17% by weight;
b. dynamically heating said slurry under a positive pressure at a temperature of 285 to 320°F.;
c. retaining said heated slurry under a posi-tive pressure for at least a few seconds;
d. releasing said pressure to cause flash off volatilization and removal of moisture laden with undesirable flavor components;
e. adding to said slurry a sulfite reducing agent in an amount of at least about 0.1% by weight of the solids in said slurry to improve the emulsification proper-ties of the soy protein; and g. drying said slurry at a temperature below about 200°F. to produce a dried protein isolate.

18. A process as set forth in Claim 17 wherein said drying is carried out at a temperature of between about 165 to 200°F.

19. A process as set forth in Claim 17 or 18 wherein said slurry is retained under a positive pressure for about 3 to 20 seconds.