Effect of residual chymotryptic activity in a trypsin preparation on peptide aggregation in a β-lactoglobulin hydrolysate

Peptide composition and peptide aggregation in beta-lactoglobulin (beta-LG) hydrolysate were studied as related to residual chymotryptic activity in a commercial trypsin (CT) preparation. Residual chymotryptic activity produced smaller and more hydrophobic peptides in tryptic hydrolysate of beta-LG, which enhanced peptide aggregation, mainly at acidic pH. The contribution of the chymotryptic peptide beta-LG 15-20 to this aggregation process appeared to be very important, but other peptides (i.e., beta-LG 41/ 43-60, 1-8 and 61-69/70 + 149-162) and residual alpha-LA may also decrease peptide solubility. When using CT mixtures in the preparation of whey protein hydrolysates, the impact of residual chymotryptic activity should not be neglected because of its influence on peptide-peptide interactions and on the resulting solubility of the hydrolyzed product. (C) 2003 Elsevier Ltd. All rights reserved.