CA1151156A - Heat gellable protein isolate - Google Patents

Abstract

ABSTRACT OF THE DISCLOSURE
Heat-gellable protein isolates are described which are capable of forming heat set gels of hardness values comparable to or exceeding that of egg white. The isolate is formed by manipulating the pH and ionic strength con-ditions of aqueous dispersion of a substantially undenatured vegetable protein isolate to provide an ionic strength greater than 0.2 and a pH up to about 6Ø

Description

5~6 HEAT G~LLABLE PROTEIN ISOLATE
The present invention relates to novel heat gellable protein isolates which are suitable for use as substitutes or extenders for egg white.
Egg white has certain functional properties which enable the material to be usefully used in various food compositions. One of those properties is the ability of aqueous dispersion thereof to heat set to a gel. Such gels are quite hard, typically having hardness values (when formed from 20~ w/w dispersions thereof) of about 35 to 40 texturometer units (T.U.), as determined by the G.F. Texturometer. The G.F. Texturometer and its operation are described in detail in an article entitled "The Texturometer - A New Instrument for Objective Texture Measurement" by H.H. Friedman et al published in J. of Food Science, Vol. 28, p. 390 (1963).
Attempts have been made to provide vegetable proteins which are capable of being heat set to gels of hardness value similar to or exceeding that of egg white, but to date, as far as the applicants are aware, none have been successful. Conventional isoelectrically-produced soy isolates produce much softer gels than egg white, such gels having hardness values of below about 20 T.U.
It has now surprisingly been found that dispersions of vegetable proteins which are heat gellable to gels of hardness values comparable to or exceeding gels produced from egg white dispersions at the same dispersion concentration can be provided by controlled manipulation of the pH and ionic strength values of an aqueous dispersion of a substantially undenatured vegetable pro-tein isolate.
Gels which are produced from dispersions which are manipulated in accordance with the present invention at the same dispersion concentratlon (ie 20~ w/w) have a hardness value of at least 35 T.U. and preferably at least about 40 T.U.

Accordingly, the present invention provides a novel vegetable protein isolate containing at least about 90% by weight of vegetable protein (as determined by K jeldahl nitrogen x 6.25) and capable of forming heat set gels from dispersions thereof, which yels have a hardness value which is at least that of a heat set gel formed from a dispersion fo egg white having the same dispersion concentration.
The present invention also provides a method of improving the heat gelation properties of a substantially undenatured vegetable protein isolate containing at least about 90% by weight of vegetable protein (as determined by Kjeldahl nitrogen x 6.25), which comprises:~a) settling the solid phase from an aqueous dispersion of protein micelles consisting of amphiphilic protein moieties and formed from at least one vegetable source material to provide an amorphous protein mass containing the substantially undenatured protein isolate, the isolate -~ having substantially no lipid content, substantially no lysinoalanine content and substantially the same lysine : content as the storage protein in the source material, and (b) subsequently treating the vegetable protein isolate with at least one food grade salt and at least one food grade acidifying agent to incorporate in a heat gellable dispersion of the protein isolate sufficient food grade salt to provide an ionic strength of the dispersion fo at least about 0.2 molar and sufficient food grade acidifying - agent to provide a pH value of the dispersion of up to about 6Ø
The present invention also includes an aqueous protein dispersion suitable for heat gelation to a gel, which comprises a substantially undenatured vegetable protein isolate containing at least about 90% by weight of vegetable protein (as determined by Kjeldahl nitrogen x 6.25) and in the form of an amorphous protein mass which is formed by settling the solid phase from an aqueous dispersion of protein micelles consisting of homogeneous amphiphilic protein moieties and formed from at least one vegetable protein source material, the product having B

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- 2a substantially no lipid content, substantially no lysinoalanine content and substantially the same lysine content as the storage protein in the source material, the isolate being dispersed in an aqueous ~., : ~ :
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phase having an ionic strength of about 0.3 to about 0.75 molar and a pH value of about 4.5 to about 5.5~
The present invention is based on the combined effect of the manipulation o~ pH and ionic strength conditions of a vegetable protein isolate which is substantially undenatured, as determined by dif~erential scanning calorimetry.
In United States Patents Nos. 4,169,090 and 4,208,323, assigned to the applicant of this application, there are described procedures for isolating protein from protein source materials by solubilizing the protein by contact of the protein source material with sodium chloride solution under critical pH and ionic strength conditions and diluting the protein solution with water 15 to a lower ionic strength to cause the formation of protein micelles in the aqueous phase which settle and are collected as an amorphous protein micellar mass (sometimes abbreviated herein as '1P~I"). The protein solution may be subjected to ultrafiltration prior to the 20 dilution step and the settling may be enhanced by centrifugation~
The protein micellar mass produced by this procedure is a novel protein isolate and represents the vegetable protein isolate from which the heat gellable 25 dispersions are formed. The novel protein isolate is described in detail in copending United States Patent No.
4,285,802, assigned to the applicant of this application.
; As described in more detail therein, the novel protein isolate is a substantially undenatured protein 30 isolate product containing at least about 90~ by weight of vegetable protein, as determined by Kjeldahl nitrogen times 6.25 and in the form of a protein micellar mass which is formed by settling the solid phase from an aqueous dispersion of protein micelles consisting of homogeneous amphiphilic protein moieties and formed from at least one vegetable protein source material. The protein isolate product has substantially no lipid content, substantially no lysinoalanine content and substantially the same lysine content as the storage 9,~

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3a protein in the source material. The isolate product may be provided in dry form by drying the amorphous protein mass.
The aqueous dispersion of protein micelles from which the isolate is settled may be formed, in accordance with the procedure of U.S. Patent No. 4, 169,090, by solubilizing the protein in the vegetable protein source material at a temperature of about 15 to 35C using a food grade salt solution having a concentration of at least 0.2 molar ionic strength and a pH of 5.5 to 6.3 to form a protein solution, and diluting the protein solution to an ionic strength of less than 0 1 molar to cause formation of the dispersion.
The aqueous dispersion of protein micelles also 15 may be formed, in accordance with the procedure of U.S.
Patent No. 4,208,323, ~y solubilizing the protein in the vegetable protein source material at a temperature of about 15 to about 35C using a food grade salt solution having a concentration of at least 0.2 molar ionic 20 strength :

5~ S6 and a pH of about 5 to about 6.8 to form a protein solution, increasing the protein concentration o~ the protein solution while maintaining the ionic strength thereof substantially constant, and diluting the concen-trated protein solution to an ionic strength below about0.2 molar to cause formation of the dispersion~
In the latter process, the food grade salt solution preferably has an ionic strength o~ about 0~2 to about 0.8 molar anda pH of about 5.3 to about 6.~. In addition, the protein concentration step is preferably effected by a membrane technique at a volume reduction factor of about 1.1 to about 6.0, as determined by the ratio of volume of protein solution and the volume of concentrated protein solution.
Further, the dilution of the concentrated protein solution is prefera~ly effected by passing the concentrated protein solution into a body of water having a temperature below about 25C and a volume sufficient to decrease the ionic strength of the concentrated protein solution to a value of about 0.06 to about 0.12 molar.
In one embodiment of the latter process, the food grade salt solution has a pH of about 5 to about 5~5 and the phosphorus content of the protein solution is decreased prior to the dilution step.
The food grade salt used in the above-described solubilization procedures usually is sodium chloride, although other salts, such as, potassium chloride or calcium chloride may be used.
In accordance with this invention, the heat gelation properties of dispersions of the protein isolate in water are improved ~y incorporating in such dispersions suffic-ient at least one food grade salt to provide an ionic strength of the dispersion of at least about O~ molar and sufficient at least one food grade acidifying agent to pro~ide a p~ of the dispersion of less than about6Ø
The ionic strength of the protein dispersion pro-vided by the at least one food grade salt usually varies from the lower limit of about 0~2 molar up to about 1.5 molar and preferably is in the range of about 0.3 to about 0.75 ' 5~ :
molar for the reasons discussed in detail below. While such ionic strength values represent a relatively high salt concen tration in terms of the heat gellable dispersion, the overall salt concentration in a food composition incorporating the heat gellable dispersion will inevitably be very much lower and invariably within tolerable le~els.
The pH of the protein dispersions may var~ from the upper limit of about 6.0 down to about 3.5 and preferably is in the range of about 4.5 to about 5.5 ~or the reasons dis-~ussed in detail below.
The incorporation of the food grade salt and foodgrade acidifying agent into the protein dispersion may be effected in a num~er of ways. One manner of incorpora-tion is to dissolve the ~ood grade salt and food grade acidifying agent directly in an aqueous dispersion of the vegetable protein isolate.
Alternatively, the food grade salt and food grade acidifying agent, in the required proportions, may be uniformly mixed with the settled solid phase from the isolation procedure after separation from the residual aqueous phase, the mixture thereupon dried and the protein dispersion is formed from the dried mixture. Such a dried mixture also may be formed by dry mixing the food grade salt, food gradeacidifying agent and dried isolate.
The intermixed dry composition which results from - the latter operations and which is capable o~ dispersion in water to form a heat~gellable d~spersion constitutes one aspect of the invention. The relative proportions of pro-tein, food grade salt and food grade acidifying agent in ~ 30 such intermixed dry compositions depends on a number of factors, including the intended protein concentration in the aqueous heat gellable dispersion to be formed therefrom, the form of the acidifying agent and the source of the food grade salt.
For example, the food grade acidifying agent may be such as to provide part of the food grade salt~ Also, the overall food grade salt concentration may be intended to be provided in part by the food system with which the protein dispersion is to be used.

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:~5~ 5;6 In general, for each 100 parts by weight of dry vegetable protein isolate, there may be mixed therewith about 0.5 to about 4.0 parts by weight of food grade acidifying agent and from 0 to about 2.5 parts by weight of food grade salt. Such a composition is capable of dispersion in water to form a dispersion of protein concentration of about 10 to about 30% w/w wherein the isclate is dispersed in an aqueous phase having an ionic strength of at least about 0.2 molar and a pH of up to about 6Ø
The food grade salt used in this invention to provide the required ionic strength usually is sodium chloride, although other food grade salts, such as, potassium chloride or calcuim chloride may be used.
The food grade acidifying agent used in this invention to provide the required pH value may be any desired food grade acid, usually hydrochloric acid, but also including phosphoric acid, citric acid, malic acid 20 and tartaric acid. The food grade acidifying agent may be of such a nature that it provides part of the ionic strength in the dispersion, for example, sodium tartrate or sodium citrate.
It has been found that an increase iJl the ionic 25 strength of the dispersion of the protein above about 0.2 molar leads to an increased hardness of heat set yel -~ formed from the dispersion up to a maximum at a given pH
up to about 6.0, before once again decreasing.
Further, as the pH is decreased, an increased 30 gel hardness is observed for the same ionic strength value above about 0.2 molar to a peak beyond which further decreases in pH value lead to decreases in gel strength. As the ionic strength of the dispersion increases, the peak gel hardness occurs at a lower pH
35 value.
There is a broad spectrum of ionic strength and pH values over which the gel strength does not significantly change and the gel strength value produced from 20% w/w dispersions usually is at least about 35 ;~

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6a T.U. and preferably at least about 40 T.U. and hence at least as good as egg white gels produced from the same concentration dispersions (35 to 40 T.U.).
For example, for soy PMM gels with no added sodium chloride in the pH range of 4.5 to 7.5, the gels were generally soft, exhibiting hardness values of 4 to 8 T.U.

, with the hardest gel (21 T.U.) being produced at pH 6.5.
These values compare with hardness values for egg white (35 to 40 T.U.).
As the concentration of added sodium chloride increasea, the magnitude of the gel hardness values - obtained increased, reaching a maximum value in excess of egg white of 48 T.U. at pH 5.0 and 0.5 M NaCl. Increased concentrations of sodium chloride in the range of 0.75 to 1.0 M over the pH range caused a slight decrease in gel hardness from this maximum. A broad region of high gel hardness was observed at sodium chloride levels above 0.3 M
and gels with hardness values above 40 T.U. were obtained in the pH range of 4O5 to 5.5. With increasing sodium chloride concentration, the pH at which maximum gel hardness occurs decreased from pH 6.5 at 0 M NaCl to pH
5.0 at 0.5 M NaCl and pH 4.5 at 1.0 M NaClO
The presence of the added salt substantially increases the dispersibility of the proteins. At low ionic strength values, from 0 to 0.1 Ml dispersibility is low, ranging from lO to 30% and gels produced under these conditions are extremely soft. At 0.2 M NaCl and above, dispersibility increases markedly to greater than 70~
and is relatively insensitive to NaCl concentration and changes in pH. The gel hardness of the heatset gels, hcwever, is independent of the dispersibility above about 30~ and both hard and soft gels may be attained under conditions where the protein dispersibility exceeds 70%.
The presence of the food grade salt affects the end properties of the gel which is formed by heat gelation of the dispersion. Gels of similar hardness value can be quite different in visual appearance. The "sl~cea~ility"
of the gels, an important factor in product application/ may -`
be determined by the Warner-Bratzler method as described in detail in an article entitled "Modification of Texture Instruments" by P. W. Voisey, J. of Texture Studies, 2 (1971~, p.l29 tol95. As the ionic strength of the dispersion increases, the sliceability of the gel, as determined by the Warner-Bratzler methodj increases before again dropping off rapidly.

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5:~56 For example, it was found -that the sliceability of a soy PMM gel was relatively independent of pH but quite sensitive to changes in soaium chloride concentration. The highest values were attained in the region of 0.3 to 0.5M
NaCl and the values decreased rapidly for higher and lower NaCl levels. The sliceability values were observed to be inferior to those for egg white gels but substantially superior to those for gels from other conventional vegetable protein isolates.
The manipulation of ~he protein dispersions formed from the protein isolate by the addition of sodium chloride and pH adjustment enables heat-set gels to be formed which have hardness values which are as good as or exceed those of egg white. This result enable the dispersions lS or dry mixes of the isolate, food grade salt and food grade acidifying agent to be used in various ~ood systems as a su~stitute or extender for egg white, where the same is used for its gelation properties more efficiently ihan the unmodified isolate.
The food system in which the compositions o~ this invention find particular utility utilize various meat analogs, including bacon analogs, such as that described in U.S. Patent No. 3,84Q,677 assigned to General Foods Corporation. The broad spectrum o~ pH and salt concentration values over which the high gel hardness values are attained permits flexibility from a processing standpoint.
Egg white is multifunctional over a wide range o~
conditions ana often is used in meat analogs for both gelation and emulsification properties. The PMM
-isolate, however, exhibits functionality which is much more sensitive to environmental conditions, so that the conditions which favour optimum gelation properties, as set forth herein, may not necessarily be those conditions which favour emulsification, so that the composition of this invention cannot be substituted directly into a - formulation which has been optimized for egg white multifunctionality.

~:~L5~56 The protein source material from which the protein isolate is formed may be any convenient salt-extractable vegetable protein source, usually an oil seed, preferably soybeans, or a legume, preferably fababeans and field peas. The responses of the isolates from differing protein sources are similar and any differences in gelation behaviour result from differences in speciflc characteristics, such as, amino acid composition, between the protein sources.
The invention is illustrated by the following examples. In the Examples, reference will be had to the accompanying drawings, wherein:
Figure 1 is a graphical representation of the effects of pH and sodium chloride concentration on the hardness of gels produced from a substantially undenatured soy protein isolate;
Figure 2 is a graphical representation of the effects of pH and sodium chloride concentration on the texture of gels produced from the soy protein isolate;
and Figure 3 is a graphical representation of the effects of p~ and sodium chloride concentration on the dispersibility of the soy protein isolate.
Example 1 This example illustrates the effect of ionic strength and pH on the gelation properties of soy PMM
dispersions.
A protein isolate was formed from soybeans following the procedure of U.S. Patent No. 4,203,323.
34.1 kg of soybean concentrate (about 50 wt.% protein) was mixed with 50 Imperial gallons of 0.35 molar sodium chloride solution at a 15% w/v concentration at a temperature of about 25C. The mixture was stirred for about 30 ~inutes at a pH of about 6.3. The aqueous protein extract was separated from residual solid matter.
The extract was concentrated on an ultrafiltration unit using a "ROMICON" (Trademark) type XM50 and a Romicon type PM50 cartridge for a time .

5~
9a sufficient to achieve a volume reduction fac-tor of four times. The Romicon ultrafiltration cartridges are manufactured by Rohm and Haas Company, the designation of "50" referring to a molecular weight cut-off of 50,000 Daltons.
The concentrate was diluted into cold water having a temperature of 7C to an ionic strength of 0.1 molar whereupon a white cloud of protein isolate formed in the dilution system. The protein dispersion was allowed to settle as a highly viscous amporphous gelatinous precipitate in the bottom of the dilution vessel.
4.2 Kg of wet PMM containing 72.7 wt.% moisture were separated from the residual aqueous phase and was freeze dried to 1.275 Kg of protein isolate which was found to be substantially undenatured (as determined by differential scanning calorimetry) and to contain 95.5 wt.% protein (as ~, ; : .

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determined by Kjeldahl nitrogen x 6.25~.
Samples o~ the dry isolate formed ky the above-described procedure were formed into 20~ w/w aqueous dispersions. The ionic strength of such dispersions was adjusted to varying values 5 from 0 M to 1 M usin~ sodium chloride and the pH of the dispersions also was adjusted to varying values from 4.5 to 7.5 by the addition of 6N HCl or 6 NNaO~I for maior varia-tions and 0.1 N HCl or 0.1N NaOH for minor adjustments.
Samples were dispersed for 30 minutes at ambient temper-ature (20 to 25C).
The protein dispersions were poured into stainlesssteel gel tubes (2 1/~ in. x 3/4 in. I.~.) with re~ovable stainless steel caps after greasing to facilitate removal of the gel. The gel tubes were heated in a boiling water bath for 45 minutes and then cooled to 20C for a minimum of 2Q minutes. The gels were removed from the tubes immediately before testing, to minimize water loss from the surfacep Each gel was sliced into three3/4 inch len~th cyl;ndérs and tested for hardness on the G.F. Texturometer using a

2-inch diameter disc plunger. Each sample was compressed twice and the peak heights measured~ The hardness was calculated according to the method of Freidman et al(men-tioned above)from the formula:
Height of First Peak x millivolts Hardness = 2 (T.U.) Voltage The hardness values obtained for the various gels were plotted graphically against the pH and NaCl concen-tration. The results are reproduced in Figure 1.
As can be seen from Figure 1, the gel hardness rapidly increased for ionic strength values abo~e 0.3 for pH values of about 4.5 to about 5.5. As the ionic strength increases, the pH at which maximum gel hardness was ` attained shifts downward, reaching a maximum of48 T.U~
at pH 5.0 and 0.5 M NaCl. Further increases in NaCl concentration were accompanied by a downward shift in the optimum pH, except that gel hardness values began to decrease slightly.

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~S~i6 The result of the pH shifts and increases in gel hardness values was a broad area of high hardness in excess of 35 T.U. occurring in the pH range of 4.5 to 5.5 and the ionic strength range of 0.3 to 0.75 M NaCl.
In contrast, gels formed from egg white under various salt concentrations and pH values exhibited relative insensitivity to pH and salt concentration variations, with gel hardness values in the range of 35 to 40 T.U. being observed.
Example 2 This Example illustrates the effect of pH and NaCl on sliceability of the gels formed from soy PMM disper-sions.
Soy PMM was prepared following the procedure of Example I and gels were formed from dispersions of the dry soy PMM at various pH and sodium chloride concentra-tions as described in Example I. me sliceabili~y of the gels was evaluated using a Warner-Bratzler (W.B.) apparatus (the details of which are described above).
The apparatus consisted of an electrically powered press and a force transducer to detect the force generated ~y deformation of the samples. The transducer signal was amplified and recorded on a Hewlett Packard Strip Chart Recorder (Model 7100B with a 200 series disc integrator).
Three 0.04 inch blades were attached to the transducer and each has a triangular hole which circumscribe a c~rcle one inch in diameter. The sample was placed through the holes of the three blades and pulled up through three 0.045 inch slots. A crosshead speed of 12 cm/sec was used, the apparatus was calibrated to read 2.5 kg full scale at 5~ sensitivity and the millivolt input to the recorder was varied to keep the sample peaks on the scale.
A recorder chart speed of 0.1 inches/min was used.
The areas of the peaks produced were measured using a mechanical integrator and reported in number of countsO
The values attained were plotted graphically against pII
and NaCl concentration and results are found in Figure 2~
The higher the area value, the greater is the sliceability of the gel.

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`-- 12 As may be seen from Figure 2, the W. B . area was found to be relatively independent of pH and most sensitive to changes in sodium chloride concentration, the areas being highest between 0.2 and 0.5 M NaCl and decreasing rapidly for higher and lower NaCl levels.
Exam~le 3 This Fxample illustrates the effect of pH and NaCl on protein dispersibility.
Soy Pr~M was prepared and dispersions were formed therefrom fo'lowing the procedures of Example I. The disper-sions which were used to form protein gels at various pH's and NaCl concentrations were centrifuged at 3000 x g for 10 minutesO The supernatant was sampled and the amount of nitrogen was determined by Rjeldahl analysis.
The percent dispersibility of the protein was expressed as a percentage of the total expected protein (20~ w/w~.
The dispersibility results obtained ~ere plotted graphically against pH and NaCl concentration and the results are found in Figure 3. As is seen f~om Figure

3, NaCl concentrations above 0.2 M result in consistently high protein dispersibility throughout the entire pH
range.
Example 4 This Example illustrates the application of pH and ionic strength adjustment to other protein source materials.
(a) P~ isolates were prepared from fababean and field peas following generally the procedure of Example 1 and gels were prepared under varying pH and NaCl concentra-tion conditions in analogous manner to that described inExample I and the hardness values determined. Similar responses to pH and NaCl concentration to those for soy were observed.
For fababeans, gels of maximum hardness value were formed under conditions of high NaCl (0~5 to 1.0 M) and low pH(4.0 to 5.5).For field peas, the corresponding conditions were NaCl 0.5 to l.OM and pH 4.0 to 5.5 . The conditions of maximum hardness varied among the protein sources and the hardest gels were observed with soy PMM.

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(b) Promine D (a commercial soy isolate formed by isoelectric precipitation and sold by Central So~) was formed into gels from 20~ w/w dispersions containing varying concentrations of sodium chloride at various pH
values following the procedures outlined in Example 1.
Gel hardness was determined and it was found that a slightly higher gel hardness in 0.2 M NaCl than in O M NaCl while soy PMM gels were significantly harder both with and without added NaCl. Promine D gels containing higher concentrations of NaCl (0.5 to 1.0 M) and at low pH (4.0 to 5.0) are very soft (4T.U.). These results indicate a gelation behaviour for this commercial isolate which is very different from soy PMM.
Example 5 This example illustrates the use of the compositions of the invention as a replacement for part of the egg white in a bacon analog.
Following the procedure outlined in U.S. Patent 20 No. 3,840,677, the red and white phases of a bacon analog were prepared utilizing the components and quantities outlined in Tables I and II of the patent.
A series of replacement levels of soy PM~I
replacing egg white ("albumen") were tested for the white 25 phase under varying pH and salt concentrations. The results are reproduced in the following Table I:
TABLE I
~ Total Egg White pH NaCl( ) Hardness( ) Cohesive-Egg White Replaced (M) (T.U.) ness (3) r _ _ 100 - 6.0 1.8 75 0.80

4.5 0.75 67 0.75 6.0 1.8 59 0.78 6.0 1.8 46 0.77 Notes: (1) The sodium chloride concentration is the basis of the aqueous phase basis and represents an overall sodium chloride concentration in the composition o~ about .
,:
.

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, 51~

l to 2wt.%.
(2) The hardness values ~easured as for the product and not for the heat set gel.
t3) The cohesiveness is determined by the texturometer as the ratio of the second peak to the area of the first peak.
Replacement of 55~ of the egg white at pH 4.5, 0.75 M NaCl (in the aqueous phase), produced a product of acceptable texture, whereas the other levels of replacement at higher p~ and NaCl concentration lead to a significant and unsatisfactory decline in the texture.
For the red phase, lO0~ replacement of egg white by soy PMM did not produce an acceptable product, but when the soy P~ also was used to replace conventional soy isolates in the red phase, a product was obtained having a texture equivalent to that of the conventional product containing egg white and conventional soy isolate.
- In summary of this disclosure, the present invention provides a novel heat-gellable protein isolate which is formed by pH and ionic strength manipulations of dispersions of protein micellar masses and which forms gels of hardness comparable to or exceeding that of egg white. Modifications are possible within the scope of the invention.

Claims (7)

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

1. A vegetable protein isolate containing at least about 90% by weight of vegetable protein (as determined by Kjeldahl nitrogen x 6.25) and capable of forming heat set gels from dispersions thereof, which gels have a hardness value which is at least that of a heat set gel formed from a dispersion of egg white having the same dispersions concentration.

2. A vegetable protein isolate capable of forming heat set gels from dispersions thereof, which gels have a hardness value of at least 40 texturometer units when measured for a heat set gel formed from a dispersion of said isolate having a protein concentration of about 20%
w/w.

3. The isolate of claim 1 of 2 wherein the vegetable protein is soybeans.

4. A method of improving the heat gelation properties of a substantially undenatured vegetable protein isolate containing at least about 90% by weight of vegetable protein (as determined by Kjeldahl nitrogen x 6.25), which comprises:
(a) settling the solid phase from an aqueous dispersion of protein micelles consisting of amphiphilic protein moieties and formed from at least one vegetable source material to provide an amorphous protein mass containing said substantially undenatured protein isolate, said isolate having substantially no lipid content, substantially no lysinoalanine content and substantially the same lysine content as the storage protein in the source material, and (b) subsequently treating said vegetable protein isolate with at least one food grade salt and at least one food grade acidifying agent to incorporate in a heat gellable dispersion of said protein isolate sufficient food grade salt to provide an ionic strength of said dispersion of at least about 0.2 molar and sufficient food grade acidifying agent to provide a pH value of said dispersion of up to about 6Ø

15a

5. The method of claim 4 wherein said ionic strength is from about 0.2 to about 1.5 molar.

6. The method of claim 4 wherein said ionic strength is from about 0.3 to about 0.75 molar.

7. The method of claim 4, 5, or 6 wherein said food grade salt is sodium chloride.