Production of antioxidant hydrolyzates from a whey protein concentrate with thermolysin: Optimization by response surface methodology

Whey protein concentrate (WPC) enriched in beta-lactoglobulin (beta-Lg) was hydrolyzed using Corolase PP (R) and thermolysin to produce hydrolyzates with antioxidant activity. The optimization of the main experimental variables involved in the process, such as type of enzyme, and hydrolysis conditions, concretely enzyme to substrate ratio, time and temperature, were evaluated using response surface methodology. A central composite circumscribed (CCC) design was employed to study the effect of the experimental variables on the antioxidant activity determined by radical scavenging potency. The parameters of the model were estimated by multiple linear regression, and the highest radical scavenging activity (2.57 mu mol Trolox/mg protein) was found in WPC hydrolyzed with thermolysin after 8 h at 80 degrees C and an enzyme/substrate ratio of 0.10 (w/w). Nineteen beta-Lg derived peptides were identified by RP-HPLC-MS/MS in this hydrolyzate. Of special interest are peptides LQKW f(58-61) and LDTDYKK f (95-101), which amino acid composition makes them potential contributors on the radical scavenging activity detected. (C) 2010 Elsevier Ltd. All rights reserved.