Effects of Enzyme Modified Soy Protein on Rennet-Induced Reconstituted Nonfat Dry Milk Coagulum Properties

Soy protein was hydrolyzed by trypsin, pepsin and α-chymotrypsin. Effects of adding hydrolyzed soy protein on rennet-induced nonfat milk coagulum texture and syneresis were studied. Pepsin-modified soy protein increased coagulum firmness and syneresis greater than untreated soy protein. Soy protein hydrolyzed with trypsin for 150 min and added to nonfat milk increased coagulum firmness greater than nonfat milk with no soy protein added. Chymotrypsin-modified soy protein acted similarly to the trypsin modified soy protein except the coagulum firmness was less than nonfat milk alone. Soy protein hydrolyzed by trypsin followed by pepsin increased coagulum firmness more than hydrolysis by a single enzyme and was close to nonfat milk without soy protein.