Soy protein concentrates by ultrafiltration

Soybean protein concentrates were produced by ultrafiltration with a commercial 4-in spiral wound module with a polyvinylidene difluoride membrane. With soy flour suspensions of 2% total solids (TS), protein content could be increased from 50% (dry basis) to 67% by ultrafiltration and/or diafiltration. Soluble sugars could be removed almost completely, but ash content of retentate solids did not decrease significantly. Higher protein contents would require removal of some of the fiber and/or manipulation of the feed environment to reduce solute-solute interactions. Protein yields were 90%. Flux decreased from 78 L/m(2)/h (LMH) with 2% TS soy flour suspension to 22 LMH at 17% TS.