Abstract: Using Lactobacillus to ferment whey protein, the antioxidant capacity of the fermentation product were analyzed. For the fermentation products, the DPPH radical scavenging rate adopted as the evaluation standard of the antioxidant capacity was 66.95%. The DPPH radical scavenging rate of graded product increased to 79% after 5kDa ultrafiltration. Tricine-SDS-PAGE electrophoresis analysis showed that, the molecular weight of the whey peptides which had antioxidant activity clearly was concentrated in less than 2kDa . Amino acid analysis of fermentation products demonstrated that, the content of the hydrophobic amino acids and aromatic amino acid closely related to the antioxidant activity were more than 70.17%. At the same time, these fermented products were full of the essential amino acids, and were suitable to develop new functional food.

Key words: whey protein, antioxidant peptide, DPPH, ultrafiltration, electrophoresis, amino acid analysis