Preparation of antioxidant enzymatic hydrolysates from alpha-lactalbumin and beta-lactoglobulin. Identification of active peptides by HPLC-MS/MS.

We have investigated the antioxidant activity of hydrolysates from whey proteins bovine alpha-lactalbumin (alpha-La) and beta-lactoglobulin A (beta-Lg A) by commercial proteases (pepsin, trypsin, chymotrypsin, thermolysin, and Corolase PP). Corolase PP was the most appropriate enzyme to obtain antioxidant hydrolysates from alpha-La and beta-Lg A (ORAC-FL values of 2.315 and 2.151 micromol of Trolox equivalent/mg of protein, respectively). A total of 42 peptide fragments were identified by HPLC-MS/MS in the beta-Lg A hydrolysate by Corolase PP. One of the sequences (Trp-Tyr-Ser-Leu-Ala-Met-Ala-Ala-Ser-Asp-Ile) possessed radical scavenging (ORAC-FL value of 2.621 micromol of Trolox equivalent/micromol of peptide) higher than that of butylated hydroxyanisole (BHA). Our results suggest that whey protein hydrolysates could be suitable as natural ingredients in enhancing antioxidant properties of functional foods and in preventing oxidation reaction in food processing.