FUNCTIONAL-PROPERTIES OF PROTEOLYTIC-ENZYME MODIFIED SOY PROTEIN ISOLATE

The effects of proteolytic enzyme modification of soy protein isolate (SPI) on its molecular and functional properties were evaluated by treating a commerical SPI, Ardex F, with Alcalase, α-chymotrypsin, trypsin, Liquozyme, and rennet. Trypsin effectively decreased the molecular size of SPI followed by Alcalase and α-chymotrypsin. Hydrolytic breakdown occurred more extensively in the α', α, and β subunits of 7S globulins than in the acidic and basic polypeptides of 11S globulins. Partial hydrolysis of SPI contributed to improving its solubility at pH 7.0 and 4.5, emulsifying capacity, and ability to undergo thermal aggregation. The extent of contribution was dependent upon the enzymes used, duration of proteolytic treatment, and functional properties sought after. © 1990, American Chemical Society. All rights reserved.