Soy Protein Isolate and Process for its Manufacture

Abstract

A soy protein isolate and method for preparing the same are disclosed. The novel soy protein isolate possesses excellent suspension stability and flavor. The process used to produce the soy protein isolate includes an enzyme hydrolysis process, and the resulting soy protein isolate can be used in acidic beverage formulations.

1 - 10 . (canceled)  
     
     
         11 . A process for producing a soy protein isolate, the process comprising: 
 dispersing white flakes produced from soybeans in a liquid to produce a soy protein extract;    separating insoluble material from the soy protein extract to form a soluble soy protein extract;    adjusting the pH of the soluble soy protein extract to about the isoelectric point of soy protein with an acid to form a precipitated soy protein mixture;    centrifuging the precipitated soy protein mixture and decanting the supernatant to form a soy protein curd;    diluting the soy protein curd with water to form a soy protein slurry;    adjusting the pH of the soy protein slurry to a pH of from about 9.5 to about 10.5 with a base to form a pH-adjusted soy protein slurry;    heating and reacting the pH-adjusted soy protein slurry with an enzyme without maintaining the pH level to form an enzyme hydrolyzed soy protein mixture; and    adjusting the pH of the enzyme hydrolyzed soy protein mixture with an acid to a pH of from about 7.0 to about 7.6;    wherein the enzyme hydrolyzed soy protein isolate has an average molecular weight of from about 12,000 Daltons to about 18,000 Daltons and a degree of hydrolysis of from about 2.9% to about 5.2%, wherein the soy protein isolate has a soluble solids index of from about 80% to about 100% at a pH of from about 7.0 to about 7.8, an average particle size of from about 15 μM to about 60 μM, and greater than 99% homogeneity in water at a pH of from about 7.0 to about 7.8 after 30 minutes, and    wherein the soy protein isolate has greater than 90% homogeneity in water at a pH of from about 7.0 to about 7.8 after 2 hours.    
     
     
         12 . The process as set forth in  claim 11  further comprising heating the pH-adjusted enzyme hydrolyzed soy protein mixture, cooling the pH-adjusted enzyme hydrolyzed soy protein mixture, and spray drying the pH-adjusted enzyme hydrolyzed soy protein mixture.  
     
     
         13 . The process as set forth in  claim 11  wherein the white flakes are dispersed in water at a pH of from about 6.4 to about 7.5.  
     
     
         14 . The process as set forth in  claim 11  wherein the white flakes are dispersed in an alkaline solution at a pH of from about 9.5 to about 10.0.  
     
     
         15 . The process as set forth in  claim 11  wherein the soy protein curd is comprised of from about 7.5% to about 16.9% soy protein (by weight dry matter), from about 82% to about 92% moisture, and from about 0.36% to about 0.8% ash (by weight dry matter).  
     
     
         16 . The process as set forth in  claim 11  wherein the soy protein slurry comprises from about 8 wt. % to about 18 wt. % solids.  
     
     
         17 . The process as set forth in  claim 11  wherein the pH of the soy protein slurry is adjusted to a pH of from about 9.5 to about 10.5 with a base selected from the group consisting of sodium hydroxide, potassium hydroxide, and mixtures thereof.  
     
     
         18 . The process as set forth in  claim 11  wherein the pH-adjusted soy protein slurry is heated to a temperature of from about 48° C. to about 58° C.  
     
     
         19 . The process as set forth in  claim 11  wherein the pH-adjusted soy protein slurry is heated directly or indirectly with steam.  
     
     
         20 . The process as set forth in  claim 11  wherein the enzyme is an alkaline protease.  
     
     
         21 . The process as set forth in  claim 11  wherein the pH-adjusted soy protein slurry is reacted with an enzyme for about 30 minutes to about 60 minutes to form the enzyme hydrolyzed soy protein mixture.  
     
     
         22 . The process as set forth in  claim 11  wherein the pH of the enzyme hydrolyzed soy protein mixture is adjusted to a pH of from about 7.0 to about 7.6 with an acid selected from the group consisting of hydrochloric acid, phosphoric acid, citric acid, and mixtures thereof.  
     
     
         23 . The process as set forth in  claim 11  wherein the pH of the enzyme hydrolyzed soy protein mixture is adjusted to about 7.2.  
     
     
         24 . The process as set forth in  claim 11  wherein the pH of the enzyme hydrolyzed soy protein mixture is adjusted with hydrochloric acid.