Influence of chemical modification of whey protein conformation on hydrolysis with pepsin and trypsin

The whey protein conformation was modified by sulfitolysis. The modified whey protein was fractioned into the precipitate and soluble fractions by lowering pH. The modified whey proteins and the two protein fractions were hydrolyzed with pepsin and trypsin. The modified whey proteins hydrolyzed more readily than intact proteins, and the formation of the peptides <2000 Da correlated with the rate of the hydrolysis of both proteins. The rate of the hydrolysis of the precipitate fraction was higher than that of the soluble fraction, while the rate of the intact protein was variably lower or higher than that of the soluble fraction. Generally, the rate of the formation of peptides <2000 Da correlated with that of the hydrolysis of both fractions. The beta -lactoglobulin antigenicity of both fractions decreased markedly during pepsin hydrolysis and approached zero in trypsin hydrolysis within 30 min. (C) 2001 Elsevier Science Ltd. All lights reserved.