Hydrolysis of Cheese Whey Proteins with Trypsin, Chymotrypsin and Carboxypeptidase A*

* Trabalho elaborado com auxílio financeiro da FAPESP (Processo no 98/11620-8) e PADCT/CNPq (Processo no 620164/97-2). ** Departamento de Alimentos e Nutrição Faculdade de Ciências Farmacêuticas UNESP 14801-902 Araraquara SP Brasil. *** Departamento de Engenharia Química UFSCar 13565-905 São Carlos SP Brasil. ABSTRACT: This work presents a method for adding value to cheese whey residues by whey proteins hydrolysis, using trypsin, chymotrypsin and carboxypeptidase A as catalysts. Sweet cheese whey was dialyzed and filtered in kaolin. Lactose and protein contents were analyzed after each step. The activities of bovine pancreas trypsin and chymotrypsin were measured at different pHs and temperatures. The optimal pH for the hydrolysis of whey proteins was 9.0 for both enzymes. Optima temperatures were 60oC for trypsin, and 50oC for chymotrypsin. Trypsin exhibited typical Michaelis-Menten behavior, but chymotrypsin did not. Electrophoretic analysis showed that neither trypsin nor chymotrypsin alone hydrolyzed whey proteins in less than three hours. Hydrolysis rates of -lactalbumin by trypsin, and of bovine serum albumin by chymotrypsin were low. When these enzymes were combined, however, all protein fractions were attacked and rates of hydrolysis were enhanced by one order of magnitude. The addition of carboxypeptidase A to the others enzymes did not improve the process yield.