| 主权项 |
1. A method of preparing a soy protein product with reduced astringency when tasted in aqueous solution at a pH below about 5, which method comprises:
(a) extracting a soy protein source with an aqueous calcium salt solution to cause solubilization of soy protein from the protein source and to form an aqueous soy protein solution, (b) separating the aqueous soy protein solution from residual soy protein source, (c) optionally diluting the aqueous soy protein solution, (d) adjusting the pH of the aqueous soy protein solution to a pH of about 1.5 to about 4.4 to produce an acidified soy protein solution, (e) optionally clarifying the acidified soy protein solution if it is not already clear, (f) alternatively from steps (b) to (e), optionally diluting and then adjusting the pH of the combined aqueous soy protein solution and residual soy protein source to a pH of about 1.5 to about 4.4 and then separating the acidified, preferably clear, soy protein solution from residual soy protein source, and (g) fractionating the proteins in the acidified soy protein solution of step (e) or (f) to separate lower molecular weight, less astringent proteins from higher molecular weight, more astringent proteins by adjusting the pH of the acidified soy protein solution to a pH value of about 5 to about 6.5 to precipitate the higher molecular weight, more astringent proteins from the acidified soy protein solution and provide a pH-adjusted soy protein solution, (h) removing the precipitate from the pH-adjusted soy protein solution, (i) adjusting the pH of the pH-adjusted soy protein solution to a pH value of about 1.5 to about 4.4, to form a re-acidified aqueous soy protein solution, and (j) optionally drying the re-acidified aqueous soy protein solution to provide a soy protein product of lesser astringency. |
