Abstract

Egg white protein powder was hydrolyzed by alcalase to produce antioxidant peptides, which were prepared under optimal enzymatic parameters that were obtained from the preliminary one-factor-at-a-time test and response surface methodology (RSM). Thereafter, the hydrolysates were sequentially fractionated by ultra filtration membranes in cut-off molecular weight (MW) of 30, 10 and 1 kDa and tested in terms of their reducing power (RP). The results show that the alcalase hydrolysates possessed strong RP ability, particularly for the fraction within <1 kDa. This fraction was further treated by high-intensity pulsed electric field (PEF) to investigate its effect on the antioxidant activity of the peptide within 6 h. The result demonstrated that the PEF could significantly improve the antioxidant activity of the treated peptide fraction within 4 h, but the effects might be reversible.

Key words: Egg white, hydrolysis, antioxidant, response surface methodology (RSM), high-intensity pulsed electric field (PEF).