EFFECTS OF HEAT AND PROTEOLYSIS ON DEAMIDATION OF FOOD PROTEINS USING PEPTIDOGLUTAMINASE

Enzymatic methods were developed for the deamidation of food proteins. Modification of proteins by peptidoglutaminase was dependent on their size and conformation. After such treatments as heat or alkali solubilization, which might have partially broken hydrogen and disulfide bonds, peptidoglutaminase deamidation of proteins increased by proteolysis as a function of percent peptide bond hydrolysis (DH), up to 54-fold at 20% DH. With prior heat treatment at 100-degrees-C for 15 min, followed by proteolysis and alkali solubilization of soy protein, casein, and gluten, over 48, 37, and 39% protein deamidation can be achieved, respectively.