Correlation between the degree of hydrolysis and the peptide profile of whey protein concentrate hydrolysates: effect of the enzyme type and reaction time.

摘要

Use of protein hydrolysates for development of new food products requires their prior characterization, including determination of degree of hydrolysis (DH) and distribution of peptides according to chain length. In this study, the DH of whey protein concentrate hydrolysates was determined by 4 methods (formol titration, soluble protein content, ortophtalaldehyde and osmometry) and peptide profile was characterized by size-exclusion HPLC. Correlations among the 4 methods, as well as between DH and peptide profiles, were established. Highest DH values were obtained by soluble protein content determination (44.7%) and derivatization with ortophtalaldehyde (20.17%) for the proteinases from Bacilluslicheniformis and Aspergillus sojae, respectively. Use of B. licheniformis proteinase was more advantageous because it produced the highest contents of di-and tripeptides (8.79%) and the lowest of large peptides (53.57%). A significant correlation (P < 0.05) between DH and contents of peptides and free amino acids was observed and the intensity of the correlation varied as a function of method and the enzyme type analysed.