Production of acid soluble soy protein isolates (“S700”)

摘要

A soy protein product having a protein content of at least about 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 by extracting a soy protein source with a salt solution, preferably aqueous sodium chloride solution, to form an aqueous protein solution having a pH of about 1.5 to 11, preferably about 5 to about 7 and separating the resulting aqueous protein solution from residual soy protein source. The protein concentration of the aqueous protein solution is increased to about 50 to about 400 g/L while the ionic strength is maintained substantially constant by using a selective membrane technique. The resulting concentrated protein solution is optionally diafiltered and a calcium salt, preferably calcium chloride, is added to the concentrated and optionally diafiltered protein solution to a conductivity of 15 to about 85 mS. Precipitate formed as a result of the calcium salt addition is removed and the resulting clarified retentate is diluted into about 2 to about 20 volumes of water prior to acidification to a pH of about 1.5 to about 4.4 to produce an acidified clear protein solution. The acidified clear protein solution is then concentrated and optionally diafiltered and optionally dried. Variations of this procedure can be used to produce a soy protein product which is soluble, transparent and heat stable in acidic aqueous environments.

主权项

1. A method of producing a soy protein product with a protein content of at least about 60 wt % (N×6.25) d.b., which comprises:
(a) extracting a soy protein source with an aqueous salt solution, optionally containing an antioxidant, at a temperature of at least about 1° C., to cause solubilization of soy protein in the soy protein source and to form an aqueous protein solution having a protein content of about 5 to about 50 g/L and a pH of about 1.5to about 11, (b) separating the aqueous protein solution from residual soy protein source, (c) optionally treating the aqueous protein solution with an adsorbent to remove colour and/or odour compounds from the aqueous protein solution, (d) increasing the protein concentration of the aqueous protein solution to about 50 to about 400 g/L while maintaining the ionic strength substantially constant by using a selective membrane technique to provide a concentrated protein solution, (e) optionally diafiltering the concentrated protein solution to provide a concentrated and optionally diafiltered protein solution, (f) optionally pasteurizing the concentrated and optionally diafiltered protein solution at a temperature of about 55° to about 70° C. for about 30 seconds to about 60 minutes followed optionally by cooling to a temperature of about 20° C. to about 35° C., (g) adding calcium salt solution, to the concentrated and optionally diafiltered protein solution to a conductivity of about 15 to about 85 mS to cause a precipitate to form in the concentrated and optionally diafiltered protein solution, (h) removing the precipitate from the concentrated protein solution to form a clarified concentrated and optionally diafiltered protein solution, (i) diluting the clarified concentrated and optionally diafiltered protein solution into about 2 to about 20 volumes of water having a temperature of about 2° to about 90° C., (j) acidifying the resulting solution to a pH of about 1.5 to about 4.4 to produce an acidified clear protein solution, (k) optionally polishing the acidified clear protein solution, (l) increasing the concentration of the acidified clear protein solution to about 50 to about 300 g/L while maintaining the ionic strength substantially constant by using a selective membrane technique to provide a second concentrated protein solution, (m) optionally diafiltering the second concentrated protein solution using water or dilute saline solution, before or after complete concentration thereof to provide a second concentrated and optionally diafiltered protein solution, (n) optionally treating the second concentrated and optionally diafiltered protein solution with an adsorbent to remove colour and/or odour compounds, and (o) optionally drying the second concentrated and optionally diafiltered protein solution to provide a soy protein product having a protein content of at least about 60 wt % (N ×6.25) d.b.