PRODUCTION OF SOLUBLE SOY PROTEIN PRODUCT FROM SOY PROTEIN MICELLAR MASS ("S200Ca:)

Abstract

A soy protein product having a protein content of at least 60 wt % (N6.25) d.b., preferably an isolate having a protein content of at least about 90 wt % (N6.25) d.b., is formed from the supernatant from the precipitation of a soy protein micellar mass. A calcium salt or other divalent salt is added to the supernatant, before concentration, after initial concentration or after final concentration, to provide a conductivity of about 2 to about 30 mS. Precipitate is removed from the resulting solution and the pH of the clear soy protein solution is optionally adjusted to about 1.5 to about 4.4. The optionally pH-adjusted clear solution is concentrated to a concentration of about 50 to about 400 g/L and the clear concentrated protein solution is optionally diafiltered prior to drying. The soy protein product is soluble in acidic media and produces transparent, heat stable solutions at low pH values and, therefore, may be used for protein fortification of soft drinks and sports drinks.

Claims

1.-29. (canceled)

30. A process of preparing a soy protein product having a protein content of at least about 60 wt % (N6.25) on a dry weight basis, which comprises: partially concentrating supernatant from precipitation of a soy protein micellar mass to a protein concentration of less than about 50 g/L, adding calcium salt or other divalent salt to the partially concentrated supernatant to provide a conductivity of about 2 mS to about 30 mS, removing precipitate from the resulting solution to leave a clear solution, optionally adjusting the pH of the clear solution to about 1.5 to about 44, further concentrating the optionally pH-adjusted clear solution to a protein content of about 50 to about 400 g/L to provide a clear concentrated soy protein solution, optionally diafiltering the clear concentrated protein solution, and drying the concentrated solution.

31. The process of claim 30 wherein said calcium salt is calcium chloride.

32. The process of claim 30 wherein said calcium salt is added to the partially concentrated supernatant to provide a conductivity of about 8 to about 15 mS.

33. The process of claim 30 wherein said optionally pH adjusted clear solution is further concentrated to a protein concentration of about 100 to about 250 g/L.

34. The process of claim 30 wherein said concentration steps are effected using a membrane having a molecular weight cut-off of about 3,000 to about 1,000,000 Daltons.

35. The process of claim 34 wherein said concentration steps are effected using a membrane having a molecular weight cut-off of about 5,000 to about 100,000 Daltons.

36. The process of claim 30 wherein a diafiltration step is effected using water, acidified water, dilute salt solution or an acidified, dilute salt solution on the soy protein solution before or after partial or complete concentration thereof.

37. The process of claim 36 wherein said diafiltration step is effected using about 2 to about 40 volumes of diafiltration solution.

38. The process of claim 37 wherein said diafiltration step is effected using about 5 to about 25 volumes of diafiltration solution.

39. The process of claim 36 wherein said diafiltration step is effected using a membrane having a molecular weight cut-off of about 3,000 to about 1,000,000 Daltons.

40. The process of claim 39 wherein said diafiltration step is effected using a membrane having a molecular weight cut-off of about 5,000 to about 100,000 Daltons.

41. The process of claim 36 wherein an antioxidant is present during at least part of the diafiltration step.

42. The process of claim 30 wherein the concentrated and optionally diafiltered soy protein solution is treated with an adsorbent to remove colour and/or odour compounds prior to said drying step.

43. The process of claim 30 wherein said soy protein product has a protein content of about 60 to about 90 wt % (N6.25) d.b.

44. The process of claim 30 wherein said soy protein product is an isolate having a protein content of at least about 90 wt % (N6.25) d.b.

45. The process of claim 30 wherein said soy protein product is an isolate having a protein content of at least about 100 wt % (N6.25) d.b.

46. The process of claim 30 wherein the pH of the clear solution is adjusted to about 2.0 to about 4.0.

47. The process of claim 30 wherein the concentrated and optionally diafiltered soy protein solution, if not already acidified, is acidified to a pH of about 2.0 to about 4.0 prior to drying.

48. The process of claim 30 wherein said clear acidified soy protein solution is subjected to a heat treatment step to inactivate heat-labile anti-nutritional factors.

49. The process of claim 48 wherein the anti-nutritional factors are heat-labile trypsin inhibitors.

50. The process of claim 48 wherein the heat treatment step also pasteurizes the acidified clear aqueous protein solution.

51. The process of claim 48 wherein said heat-treatment is effected at a temperature of about 70 to about 100 C. for about 10 seconds to about sixty minutes.

52. The process of claim 51 wherein said heat-treatment is effected at a temperature of about 85 to about 95 C. for about 30 seconds to about 5 minutes.

53. The process of claim 48 wherein the heat-treated clear acidified soy protein solution is cooled to a temperature of about 2 to about 60 C. for further processing.

54. The process of claim 53 wherein the heat-treated clear acidified soy protein solution is cooled to a temperature of about 20 to about 35 C. for further processing.

55. The process of claim 36 wherein the concentration and/or optional diafiltration step are operated in a manner favourable to the removal of trypsin inhibitors.

56. The process of claim 30 wherein a reducing agent is added to the supernatant to disrupt or rearrange the disulfide bonds of trypsin inhibitors to achieve a reduction in trypsin inhibitor activity.

57. The process of claim 36 wherein a reducing agent is present during the concentration and/or optional diafiltration step to disrupt or rearrange the disulfide bonds of trypsin inhibitors to achieve a reduction in trypsin inhibitor activity.

58. The process of claim 30 wherein a reducing agent is added to the concentrated and optionally diafiltered soy protein solution prior to drying and/or the dried soy protein product to disrupt or rearrange the disulfide bonds of trypsin inhibitors to achieve a reduction in trypsin inhibitor activity.

59.-207. (canceled)

Description

EXAMPLES

Example 1

[0096] This Example illustrates the production of protein micellar mass (S300), supernatant derived protein isolate (S200) and calcium modified supernatant derived protein isolate (S200Ca) from soy.

[0097] a kg of defatted, minimally heat processed soy flour was added to b L of c M NaCl solution at ambient temperature and agitated for 60 minutes to provide an aqueous protein solution. The residual soy flour was removed and the resulting protein solution was clarified by centrifugation and filtration to produce d L of filtered protein solution having a protein content of e % by weight.

[0098] The protein extract solution was reduced to f kg by concentration on a g membrane having a molecular weight cutoff of h Daltons producing a concentrated protein solution with a protein content of T % by weight.

[0099] The conductivity of the concentrated protein solution was T mS.

[0100] Concentrated sodium chloride solution was added to the retentate to raise the conductivity to k mS. The concentrated protein solution at l C. was then diluted m into cold RO water having a temperature n C. A white cloud formed immediately. The supernatant was removed and the precipitated, viscous, sticky mass (PMM) was recovered by centrifugation in a yield of o wt % of the filtered protein solution. The dried PMM derived protein was found to have a protein content of p % (N6.25) d.b. The product was given a designation q 5300.

[0101] The parameters a to q are set forth in the following Table 1:

TABLE-US-00001 TABLE 1 Parameters for the production of S300 q S005-J27-08A S005-K19-08A a 10 10 b 200 200 c 0.15 0.50 d 185 165 e 0.70 1.34 f 5.28 12.06 g PES PES h 100,000 100,000 i 21.28 17.51 j 9.45 24.9 k 21.4 24.9 l 27.8 30 m 1:10 1:5 n 1.6 4 o 18.5 20.8 p 91.31 99.66

[0102] The supernatants from these two runs were processed in different ways. The supernatant from the S005-J27-08A run was processed without calcium modification. In this run, 65 L of supernatant was concentrated to a volume of 5 L on a PES membrane with a molecular weight cutoff of 10,000 Daltons then diafiltered with 25 L of reverse osmosis purified water on the same membrane. The diafiltered retentate had a protein concentration of 12.60 wt %. With the additional protein recovered from the supernatant, the overall recovery of the filtered protein solution was 69.2%. The diafiltered retentate was dried to form a product with a protein content of 98.76% (N6.25) d.b. The product was given the designation S005-J27-08A S200.

[0103] The supernatant from run S005-K19-08A was processed with calcium modification. To 65 L of supernatant was added 0.336 kg of CaCl.sub.2, which raised the conductivity of the solution from 6.31 mS to 12.65 mS. The precipitate that formed was removed by centrifugation and then the pH of the centrate adjusted to 3 with diluted HCl. The acidified centrate was then concentrated from a volume of 66 L to a volume of 5 L on a PES membrane with a molecular weight cut-off of 10,000 Daltons. The concentrate was then diafiltered on the same membrane with 25 L of reverse osmosis purified water adjusted to pH 3 with diluted HCl. With the additional protein recovered from the supernatant, the overall recovery of the filtered protein solution was 37.1%. The diafiltered retentate was dried to produce a product with a protein content of 98.01% (N6.25) d.b. The product was given the designation S005-K19-08A S200Ca.

[0104] The colour of the dry powdered products was assessed with a HunterLab ColorQuest XE instrument in reflectance mode. The colour values are set forth in the following Table 2:

TABLE-US-00002 TABLE 2 HunterLab scores for dry products sample L* a* b* S005-J27-08A S300 87.06 0.28 10.04 S005-K19-08A S300 85.98 0.72 10.91 S005-J27-08A S200 84.51 0.56 10.51 S005-K19-08A S200Ca 86.87 0.58 9.53

[0105] As may be seen from Table 2, the dry colour of all the products was quite light.

Example 2

[0106] This Example contains an evaluation of the heat stability in water of the soy protein isolates produced by the method of Example 1 (S300, S200, S200Ca).

[0107] A 2% w/v protein solution of each product in water was produced and the pH adjusted to 3. The clarity of these solutions was assessed by haze measurement with the HunterLab ColorQuest XE instrument in transmission mode. The solutions were then heated to 95 C., held at this temperature for 30 seconds and then immediately cooled to room temperature in an ice bath. The clarity of the heat treated solutions was then measured again.

[0108] The clarity of the protein solutions before and after heating is set forth in the following Table 3:

TABLE-US-00003 TABLE 3 Effect of heat treatment on clarity of various samples Haze (%) Haze (%) sample before heating after heating S005-J27-08A S300 24.9 21.1 S005-K19-08A S300 30.5 29.6 S005-J27-08A S200 11.0 3.2 S005-K19-08A S200Ca 7.3 7.9

[0109] As can be seen in Table 3, the S200 and S200Ca samples gave quite clear solutions in water at pH 3. The solutions of the S300 samples were not as clear. All of the samples were heat stable, with the haze level essentially staying constant upon heating, or actually improving.

Example 3

[0110] This Example contains an evaluation of the solubility in water of the soy protein isolates produced by the method of Example 1 (S300, 5200, S200Ca). Solubility was tested based on protein solubility (termed protein method, a modified version of the procedure of Mon et al., J. Food Sci. 50:1715-1718) and total product solubility (termed pellet method).

[0111] Sufficient protein powder to supply 0.5 g of protein was weighed into a beaker and then a small amount of reverse osmosis (RO) purified water was added and the mixture stirred until a smooth paste formed. Additional water was then added to bring the volume to approximately 45 ml. The contents of the beaker were then slowly stirred for 60 minutes using a magnetic stirrer. The pH was determined immediately after dispersing the protein and was adjusted to the appropriate level (2, 3, 4, 5, 6 or 7) with diluted NaOH or HCl. A sample was also prepared at natural pH. For the pH adjusted samples, the pH was measured and corrected two times during the 60 minutes stirring. After the 60 minutes of stirring, the samples were made up to 50 ml total volume with RO water, yielding a 1% w/v protein dispersion. The protein content of the dispersions was measured using a LECO FP528 Nitrogen Determinator. Aliquots (20 ml) of the dispersions were then transferred to pre-weighed centrifuge tubes that had been dried overnight in a 100 C. oven then cooled in a desiccator and the tubes capped. The samples were centrifuged at 7800 g for 10 minutes, which sedimented insoluble material and yielded a clear supernatant. The protein content of the supernatant was measured by LECO analysis and then the supernatant and the tube lids were discarded and the pellet material dried overnight in an oven set at 100 C. The next morning the tubes were transferred to a desiccator and allowed to cool. The weight of dry pellet material was recorded. The dry weight of the initial protein powder was calculated by multiplying the weight of powder used by a factor of ((100moisture content of the powder (%))/100). Solubility of the product was then calculated two different ways:

Solubility (protein method) (%)=(% protein in supernatant/% protein in initial dispersion)1001)

Solubility (pellet method) (%)=(1(weight dry insoluble pellet material/((weight of 20 ml of dispersion/weight of 50 ml of dispersion)initial weight dry protein powder)))1002)

[0112] The natural pH values of the protein isolates produced in Example 1 in water (1% protein) are shown in Table 4:

TABLE-US-00004 TABLE 4 Natural pH of protein solution prepared in water at 1% protein Batch Product Natural pH S005-J27-08A S300 6.67 S005-K19-08A S300 6.76 S005-J27-08A S200 6.70 S005-K19-08A S200Ca 3.29

[0113] The solubility results obtained are set forth in the following Tables 5 and 6:

TABLE-US-00005 TABLE 5 Solubility of products at different pH values based on protein method Solubility (Protein method) (%) Batch Product pH 2 pH 3 pH 4 pH 5 pH 6 pH 7 Nat. pH S005-J27-08A S300 100 94.2 43.4 19.1 91.9 99.1 95.0 S005-K19-08A S300 100 100 85.3 8.1 23.7 100 94.7 S005-J27-08A S200 91.5 100 98.8 0.0 76.7 94.4 89.5 S005-K19-08A S200Ca 94.7 100 100 20 38 66.3 100

TABLE-US-00006 TABLE 6 Solubility of products at different pH values based on pellet method Solubility (pellet method) (%) Nat. Batch Product pH 2 pH 3 pH 4 pH 5 pH 6 pH 7 pH S005-J27-08A S300 97.1 97.0 55.4 29.3 91.7 94.5 86.9 S005-K19-08A S300 96.5 96.1 76.3 5.7 29.1 93.1 86.8 S005-J27-08A S200 96.9 97.8 96.3 15.1 86.1 97.9 98.1 S005-K19-08A S200Ca 98.2 95.8 97.2 31.4 55.0 71.1 98.3

[0114] As can be seen from the results of Tables 5 and 6, the S300 products were very soluble at pH values 2, 3 and 7. The S200 was very soluble at pH 2 to 4 and 7. The S200Ca was very soluble in the range of pH 2 to 4.

Example 4

[0115] This Example contains an evaluation of the clarity in water of the soy protein isolates produced by the method of Example 1 (S300, S200, S200Ca).

[0116] The clarity of the 1% w/v protein solutions prepared as described in Example 3 was assessed by measuring the absorbance at 600 nm, with a lower absorbance score indicating greater clarity. Analysis of the samples on a HunterLab ColorQuest XE instrument in transmission mode also provided a percentage haze reading, another measure of clarity.

[0117] The clarity results are set forth in the following Tables 7 and 8:

TABLE-US-00007 TABLE 7 Clarity of protein solutions at different pH values as assessed by A600 A600 Batch Product pH 2 pH 3 pH 4 pH 5 pH 6 pH 7 Nat. pH S005-J27-08A S300 0.025 0.064 >3.0 >3.0 1.568 0.819 2.482 S005-K19-08A S300 0.059 0.117 1.995 >3.0 >3.0 0.319 0.468 S005-J27-08A S200 0.053 0.066 0.127 >3.0 1.064 0.070 0.080 S005-K19-08A S200Ca 0.031 0.040 0.066 >3.0 >3.0 1.922 0.047

TABLE-US-00008 TABLE 8 Clarity of protein solutions at different pH values as assessed by HunterLab analysis HunterLab haze reading (%) Nat. Batch Product pH 2 pH 3 pH 4 pH 5 pH 6 pH 7 pH S005-J27-08A S300 8.1 16.3 98.9 99.9 97.6 89.5 98.8 S005-K19-08A S300 5.8 16.9 92.4 93.4 93.4 40.2 54.1 S005-J27-08A S200 5.6 6.4 14.4 97.4 86.5 8.1 9.2 S005-K19-08A S200Ca 1.2 3.3 7.1 93.6 92.9 92.4 2.9

[0118] As can be seen from the results of Tables 7 and 8, solutions of 5300 were clear at pH 2 and slightly hazy at pH 3. Solutions of this product at the higher pH values were quite hazy. Solutions of 5200 and S200Ca were clear in the pH range 2 to 4 and the S200 solution was also clear at natural pH and pH 7.

Example 5

[0119] This Example contains an evaluation of the solubility in a soft drink (Sprite) and sports drink (Orange Gatorade) of the soy protein isolates produced by the method of Example 1 (S300, 5200, S200Ca). The solubility was determined with the protein added to the beverages with no pH correction and again with the pH of the protein fortified beverages adjusted to the level of the original beverages.

[0120] When the solubility was assessed with no pH correction, a sufficient amount of protein powder to supply 1 g of protein was weighed into a beaker and a small amount of beverage was added and stirred until a smooth paste formed. Additional beverage was added to bring the volume to 50 ml, and then the solutions were stirred slowly on a magnetic stirrer for 60 minutes to yield a 2% protein w/v dispersion. The protein content of the samples was analyzed using a LECO FP528 Nitrogen Determinator then an aliquot of the protein containing beverages was centrifuged at 7800 g for 10 minutes and the protein content of the supernatant measured.

Solubility (%)=(% protein in supernatant/% protein in initial dispersion)100

[0121] When the solubility was assessed with pH correction, the pH of the soft drink (Sprite) (3.39) and sports drink (Orange Gatorade) (3.19) without protein was measured. A sufficient amount of protein powder to supply 1 g of protein was weighed into a beaker and a small amount of beverage was added and stirred until a smooth paste formed. Additional beverage was added to bring the volume to approximately 45 ml, and then the solutions were stirred slowly on a magnetic stirrer for 60 minutes. The pH of the protein containing beverages was measured and then adjusted to the original no-protein pH with HCl or NaOH as necessary. The total volume of each solution was then brought to 50 ml with additional beverage, yielding a 2% protein w/v dispersion. The protein content of the samples was analyzed using a LECO FP528 Nitrogen Determinator then an aliquot of the protein containing beverages was centrifuged at 7800 g for 10 minutes and the protein content of the supernatant measured.

Solubility (%)=(% protein in supernatant/% protein in initial dispersion)100

[0122] The results obtained are set forth in the following Table 9:

TABLE-US-00009 TABLE 9 Solubility of products in Sprite and Orange Gatorade no pH correction pH correction Solubility Solubility Solubility (%) in Solubility (%) in (%) in Orange (%) in Orange Batch Product Sprite Gatorade Sprite Gatorade S005-J27-08A S300 25.6 42.2 87.9 90.3 S005-K19-08A S300 4.8 71.0 95.3 85.2 S005-J27-08A S200 17.3 69.9 66.5 74.4 S005-K19-08A S200Ca 95.7 100 94.1 100

[0123] As can be seen from the results of Table 9, the S200Ca was the product with the best solubility in the Sprite and Orange Gatorade. This is an acidified product and so had little effect on the beverage pH. The remaining products were not acidified and so their solubility was improved by pH correction of the beverages. After pH correction, the solubility of the 5300 products was quite good but the solubility of the 5200 was surprisingly low, given the solubility results obtained in water in Example 3.

Example 6

[0124] This Example contains an evaluation of the clarity in a soft drink and sports drink of the soy protein isolates produced by the method of Example 1 (S300, 5200, S200Ca).

[0125] The clarity of the 2% w/v protein dispersions prepared in soft drink (Sprite) and sports drink (Orange Gatorade) in Example 5 were assessed using the methods described in Example 4. For the absorbance measurements at 600 nm, the spectrophotometer was blanked with the appropriate beverage before the measurement was performed.

[0126] The results obtained are set forth in the following Tables 10 and 11:

TABLE-US-00010 TABLE 10 Clarity (A600) of products in Sprite and Orange Gatorade no pH correction pH correction A600 in A600 in A600 in Orange A600 in Orange Batch Product Sprite Gatorade Sprite Gatorade S005-J27-08A S300 >3.0 >3.0 1.730 1.740 S005-K19-08A S300 >3.0 >3.0 1.339 1.028 S005-J27-08A S200 >3.0 2.816 1.560 1.560 S005-K19-08A S200Ca 0.084 0.019 0.093 0.071

TABLE-US-00011 TABLE 11 HunterLab haze readings for products in Sprite and Orange Gatorade no pH correction pH correction haze haze haze (%) in haze (%) in (%) in Orange (%) in Orange Batch Product Sprite Gatorade Sprite Gatorade no protein 0.0 44.0 0.0 44.0 S005-J27-08A S300 97.7 98.1 89.3 89.9 S005-K19-08A S300 93.6 93.5 94.9 86.3 S005-J27-08A S200 97.4 98.2 88.6 90.4 S005-K19-08A S200Ca 12.3 46.7 19.5 53.3

[0127] As can be seen from the results of Tables 10 and 11, the S200Ca product had the least impact on clarity in Sprite and Orange Gatorade. However, the S200Ca in Sprite was slightly hazy, particularly when tested with pH correction. The Sprite and Orange Gatorade samples containing 5300 and 5200 were very hazy regardless of whether pH correction was employed.

Example 7

[0128] This Example illustrates the production of a soy protein isolate derived from concentrated retentate (S500) from a sodium chloride extraction.

[0129] 12.5 kg of defatted, minimally heat processed soy flour was added to 125 L of 0.15 M NaCl solution at ambient temperature and agitated for 30 minutes to provide an aqueous protein solution. The residual soy flour was removed and the resulting protein solution was clarified by centrifugation and filtration to produce 97 L of filtered protein solution having a protein content of 1.14% by weight.

[0130] The protein extract solution was reduced in volume to 7 L by concentration on a PVDF membrane having a molecular weight cutoff of 5,000 daltons, producing a concentrated protein solution with a protein content of 14.83% by weight.

[0131] The concentrated protein solution was then diafiltered using 14 L of 0.075 M NaCl solution. The diafiltered retentate had a final weight of 6.14 kg and a protein content of 14.16% by weight in a yield of 78.4 wt % of the filtered protein solution. The diafiltered retentate was dried to form a product with a protein content of 95.45% (N6.25) d.b. The product was given the designation 5005-L17-08A 5500.

[0132] A 3.2% w/v protein solution of 5500 was prepared in water and the pH lowered to 3 with diluted HCl. The colour and clarity was then assessed using a HunterLab ColorQuest XE instrument operated in transmission mode.

[0133] The colour and clarity values are set forth in the following Table 12:

TABLE-US-00012 TABLE 12 HunterLab scores for 3.2% protein solution of S005-L17-08A S500 at pH 3 sample L* a* b* haze (%) S500 94.86 1.15 15.45 22.0

[0134] As may be seen from Table 12, the colour of the 5500 solution at pH 3 was quite light but the solution was also hazy.

[0135] The colour of the dry powder was also assessed with the HunterLab ColorQuest XE instrument in reflectance mode. The colour values are set forth in the following Table 13:

TABLE-US-00013 TABLE 13 HunterLab scores for dry S005-L17-08A S500 sample L* a* b* S500 84.71 0.14 14.88

[0136] As may be seen from Table 13, the dry colour of the product was quite light.

Example 8

[0137] This Example contains an evaluation of the heat stability in water of the soy protein isolate produced by the method of Example 7 (S500).

[0138] A 2% w/v protein solution of the product in water was produced and the pH adjusted to 3. The clarity of this solution was assessed by haze measurement with a HunterLab ColorQuest XE instrument in transmission mode. The solution was then heated to 95 C., held at this temperature for 30 seconds and then immediately cooled to room temperature in an ice bath. The clarity of the heat treated solution was then measured again.

[0139] The clarity of the protein solution before and after heating is set forth in the following Table 14:

TABLE-US-00014 TABLE 14 Effect of heat treatment on clarity of S005-L17-08A S500 solution Haze (%) Haze (%) sample before heating after heating S500 7.9 9.8

[0140] As can be seen in Table 14, the S500 sample gave quite a clear solution in water at pH 3. The sample was heat stable, with the haze level only slightly changed upon heating.

Example 9

[0141] This Example contains an evaluation of the solubility in water of the soy protein isolate produced by the method of Example 7 (S500). Solubility was tested based on protein solubility (termed protein method, a modified version of the procedure of Morr et al., J. Food Sci. 50:1715-1718) and total product solubility (termed pellet method).

[0142] Sufficient protein powder to supply 0.5 g of protein was weighed into a beaker and then a small amount of reverse osmosis (RO) purified water was added and the mixture stirred until a smooth paste formed. Additional water was then added to bring the volume to approximately 45 ml. The contents of the beaker were then slowly stirred for 60 minutes using a magnetic stirrer. The pH was determined immediately after dispersing the protein and was adjusted to the appropriate level (2, 3, 4, 5, 6 or 7) with diluted NaOH or HCl. A sample was also prepared at natural pH. For the pH adjusted samples, the pH was measured and corrected two times during the 60 minutes stirring. After the 60 minutes of stirring, the samples were made up to 50 ml total volume with RO water, yielding a 1% w/v protein dispersion. The protein content of the dispersions was measured using a LECO FP528 Nitrogen Determinator. Aliquots (20 ml) of the dispersions were then transferred to pre-weighed centrifuge tubes that had been dried overnight in a 100 C. oven then cooled in a desiccator and the tubes capped. The samples were centrifuged at 7800 g for 10 minutes, which sedimented insoluble material and yielded a clear supernatant. The protein content of the supernatant was measured by LECO analysis and then the supernatant and the tube lids were discarded and the pellet material dried overnight in an oven set at 100 C. The next morning the tubes were transferred to a desiccator and allowed to cool. The weight of dry pellet material was recorded. The dry weight of the initial protein powder was calculated by multiplying the weight of powder used by a factor of ((100moisture content of the powder (%))/100). Solubility of the product was then calculated two different ways:

Solubility (protein method) (%)=(% protein in supernatant/% protein in initial dispersion)1001)

Solubility (pellet method) (%)=(1(weight dry insoluble pellet material/((weight of 20 ml of dispersion/weight of 50 ml of dispersion)initial weight dry protein powder)))1002)

[0143] The natural pH value of the protein isolate produced in Example 7 in water (1% protein) is shown in Table 15:

TABLE-US-00015 TABLE 15 Natural pH of S500 solution prepared in water at 1% protein Batch Product Natural pH S005-L17-08A S500 6.61

[0144] The solubility results obtained are set forth in the following Tables 16 and 17:

TABLE-US-00016 TABLE 16 Solubility of S500 at different pH values based on protein method Solubility (protein method) (%) Nat. Batch Product pH 2 pH 3 pH 4 pH 5 pH 6 pH 7 pH S005-L17-08A S500 92.6 100 60.4 26.9 88.3 100 92.6

TABLE-US-00017 TABLE 17 Solubility of S500 at different pH values based on pellet method Solubility (pellet method) (%) Nat. Batch Product pH 2 pH 3 pH 4 pH 5 pH 6 pH 7 pH S005-L17-08A S500 97.8 97.5 68.3 30.3 84.9 97.4 97.6

[0145] As can be seen from the results of Tables 16 and 17, the S500 product was very soluble at pH 2, 3 and 7 and at the natural pH.

Example 10

[0146] This Example contains an evaluation of the clarity in water of the soy protein isolate produced by the method of Example 7 (S500).

[0147] The clarity of the 1% w/v protein solution prepared as described in Example 9 was assessed by measuring the absorbance at 600 nm, with a lower absorbance score indicating greater clarity. Analysis of the samples on a HunterLab ColorQuest XE instrument in transmission mode also provided a percentage haze reading, another measure of clarity.

[0148] The clarity results are set forth in the following Tables 18 and 19:

TABLE-US-00018 TABLE 18 Clarity of S500 solution at different pH values as assessed by A600 A600 Prod- pH pH Nat. Batch uct pH 2 pH 3 4 5 pH 6 pH 7 pH S005-L17-08A S500 0.020 0.044 >3.0 >3.0 1.499 0.048 0.061

TABLE-US-00019 TABLE 19 Clarity of S500 solution at different pH values as assessed by HunterLab analysis HunterLab haze reading (%) Nat. Batch Product pH 2 pH 3 pH 4 pH 5 pH 6 pH 7 pH S005-L17-08A S500 0.6 6.5 95.3 95.9 90.8 7.0 5.5

[0149] As can be seen from the results of Tables 18 and 19, solutions of 5500 had excellent clarity at pH 2, 3 and 7 and at natural pH.

Example 11

[0150] This Example contains an evaluation of the solubility in a soft drink (Sprite) and sports drink (Orange Gatorade) of the soy protein isolate produced by the method of Example 7 (S500). The solubility was determined with the protein added to the beverages with no pH correction and again with the pH of the protein fortified beverages adjusted to the level of the original beverages.

[0151] When the solubility was assessed with no pH correction, a sufficient amount of protein powder to supply 1 g of protein was weighed into a beaker and a small amount of beverage was added and stirred until a smooth paste formed. Additional beverage was added to bring the volume to 50 ml, and then the solutions were stirred slowly on a magnetic stirrer for 60 minutes to yield a 2% protein w/v dispersion. The protein content of the samples was analyzed using a LECO FP528 Nitrogen Determinator then an aliquot of the protein containing beverages was centrifuged at 7800 g for 10 minutes and the protein content of the supernatant measured.

Solubility (%)=(% protein in supernatant/% protein in initial dispersion)100

[0152] When the solubility was assessed with pH correction, the pH of the soft drink (Sprite) (3.39) and sports drink (Orange Gatorade) (3.19) without protein was measured. A sufficient amount of protein powder to supply 1 g of protein was weighed into a beaker and a small amount of beverage was added and stirred until a smooth paste formed. Additional beverage was added to bring the volume to approximately 45 ml, and then the solutions were stirred slowly on a magnetic stirrer for 60 minutes. The pH of the protein containing beverages was measured and then adjusted to the original no-protein pH with HCl or NaOH as necessary. The total volume of each solution was then brought to 50 ml with additional beverage, yielding a 2% protein w/v dispersion. The protein content of the samples was analyzed using a LECO FP528 Nitrogen Determinator then an aliquot of the protein containing beverages was centrifuged at 7800 g for 10 minutes and the protein content of the supernatant measured.

Solubility (%)=(% protein in supernatant/% protein in initial dispersion)100

[0153] The results obtained are set forth in the following Table 20:

TABLE-US-00020 TABLE 20 Solubility of S500 in Sprite and Orange Gatorade no pH correction pH correction Solubility Solubility Solubility (%) in Solubility (%) in (%) in Orange (%) in Orange Batch Product Sprite Gatorade Sprite Gatorade S005-L17-08A S500 22.5 50.0 82.0 79.9

[0154] As can be seen from the results of Table 20, the 5500 was not very soluble in the beverages without pH adjustment. This can partially be attributed to the fact that the S500 is not an acidified product. Correction of the pH did improve the solubility of 5500 in both beverages, although the protein was still not completely soluble.

Example 12

[0155] This Example contains an evaluation of the clarity in a soft drink and sports drink of the soy protein isolate produced by the method of Example 7 (S500).

[0156] The clarity of the 2% w/v protein dispersions prepared in soft drink (Sprite) and sports drink (Orange Gatorade) in Example 11 were assessed using the methods described in Example 10. For the absorbance measurements at 600 nm, the spectrophotometer was blanked with the appropriate beverage before the measurement was performed.

[0157] The results obtained are set forth in the following Tables 21 and 22:

TABLE-US-00021 TABLE 21 Clarity (A600) of S500 in Sprite and Orange Gatorade no pH correction pH correction A600 in A600 in A600 in Orange A600 in Orange Batch Product Sprite Gatorade Sprite Gatorade S005-L17-08A S500 >3.0 >3.0 1.056 1.710

TABLE-US-00022 TABLE 22 HunterLab haze readings for S500 in Sprite and Orange Gatorade no pH correction pH correction haze haze haze (%) in haze (%) in (%) in Orange (%) in Orange Batch Product Sprite Gatorade Sprite Gatorade no protein 0.0 44.0 0.0 44.0 S005-L17-08A S500 97.5 98.1 83.6 98.2

[0158] As may be seen from the results in Tables 21 and 22, Sprite and Orange Gatorade with added 5500 were very hazy, with perhaps only slight improvement achieved by correcting the pH.

SUMMARY OF THE DISCLOSURE

[0159] In summary of this disclosure, there are produced soy protein isolates which can provide heat stable and clear aqueous solutions at acid pH values. Modifications are possible within the scope of this invention.