PREPARATION OF A GEL OF PARTIALLY HEAT-DENATURED WHEY-PROTEIN BY PROTEOLYTIC DIGESTION

After heating 10 % (w/w) of whey protein isolate (WPI) solution to 90 degrees C for 10 min, the partially heat-denatured WPI solution was su bjected to proteolytic digestion with trypsin, papain, pronase, pepsin and protease at neutral pHs. The results indicate that 3-dimensional gel networks were formed after proteolytic digestion with trypsin, pap ain, pronase and protease within 8, 2, 4 and 1.3 h, respectively, but not with pepsin. Gelation was considered a result of hydrolyzation of the soluble aggregates of WPI following an interaction between them. T hese 4 proteolytic digestion-induced gels were generated in a similar mechanism, because similar SDS-PAGE patterns were obtained. The gel st rength of the proteolytic digestion-induced gels depended on the pretr eatment of heating temperature and the degree of hydrolysis attained.