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 % (N×6.25) d.b., preferably an isolate having a protein content of at least about 90 wt % (N×6.25) 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.

1 . A process of preparing a soy protein product having a protein content of at least about 60 wt % (N×6.25) on a dry weight basis, which comprises:
 adding calcium salt or other divalent salt to supernatant from the precipitation of a soy protein micellar mass 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 4.4, 
 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. 
 
     
     
         2 . The process of  claim 1  wherein said calcium salt is calcium chloride. 
     
     
         3 . The process of  claim 1  wherein said calcium salt is added to the supernatant to provide a conductivity of about 8 to about 15 mS. 
     
     
         4 . The process of  claim 1  wherein the optionally pH adjusted clear solution is concentrated to a protein concentration of about 100 to about 250 g/L. 
     
     
         5 . The process of  claim 1  wherein the optionally pH adjusted clear solution is concentrated using a membrane having a molecular weight cut-off of about 3,000 to about 1,000,000 Daltons. 
     
     
         6 . The process of  claim 5  wherein the optionally pH adjusted clear solution is concentrated using a membrane having a molecular weight cut-off of about 5,000 to about 100,000 Daltons. 
     
     
         7 . The process of  claim 1  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 complete concentration thereof. 
     
     
         8 . The process of  claim 7  wherein said diafiltration step is effected using about 2 to about 40 volumes of diafiltration solution. 
     
     
         9 . The process of  claim 8  wherein said diafiltration step is effected using about 5 to about 25 volumes of diafiltration solution. 
     
     
         10 . The process of  claim 7  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. 
     
     
         11 . The process of  claim 10  wherein said diafiltration step is effected using a membrane having a molecular weight cut-off of about 5,000 to about 100,000 Daltons. 
     
     
         12 . The process of  claim 7  wherein an antioxidant is present during at least part of the diafiltration step. 
     
     
         13 . The process of  claim 1  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. 
     
     
         14 . The process of  claim 1  wherein said soy protein product has a protein content of about 60 to about 90 wt % (N×6.25) d.b. 
     
     
         15 . The process of  claim 1  wherein said soy protein product is an isolate having a protein content of at least about 90 wt % (N×6.25) d.b. 
     
     
         16 . The process of  claim 1  wherein said soy protein product is an isolate having a protein content of at least about 100 wt % (N×6.25) d.b. 
     
     
         17 . The process of  claim 1  wherein the pH of the clear solution is adjusted to about 2.0 to about 4.0. 
     
     
         18 . The process of  claim 1  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. 
     
     
         19 . The process of  claim 1  wherein said clear acidified soy protein solution is subjected to a heat treatment step to inactivate heat-labile anti-nutritional factors. 
     
     
         20 . The process of  claim 19  wherein the anti-nutritional factors are heat-labile trypsin inhibitors. 
     
     
         21 . The process of  claim 19  wherein the heat treatment step also pasteurizes the acidified clear aqueous protein solution. 
     
     
         22 . The process of  claim 19  wherein said heat-treatment is effected at a temperature of about 70° to about 100° C. for about 10 seconds to about sixty minutes. 
     
     
         23 . The process of  claim 22  wherein said heat-treatment is effected at a temperature of about 85° to about 95° C. for about 30 seconds to about 5 minutes. 
     
     
         24 . The process of  claim 19  wherein the heat-treated clear acidified soy protein solution is cooled to a temperature of about 2° to about 60° C. for further processing. 
     
     
         25 . The process of  claim 24  wherein the heat-treated clear acidified soy protein solution is cooled to a temperature of about 20° to about 35° C. for further processing. 
     
     
         26 . The process of  claim 7  wherein the concentration and/or optional diafiltration step are operated in a manner favourable to the removal of trypsin inhibitors. 
     
     
         27 . The process of  claim 1  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. 
     
     
         28 . The process of  claim 7  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. 
     
     
         29 . The process of  claim 1  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. 
     
     
         30 . A process of preparing a soy protein product having a protein content of at least about 60 wt % (N×6.25) on a dry weight basis, which comprises:
 partially concentrating the supernatant from the 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 4.4, 
 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 % (N×6.25) 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 % (N×6.25) 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 % (N×6.25) 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)