Abstract:
This study aimed to investigate the hydrolysis characteristics of walnut protein hydrolysates and identify low-bitterness antioxidant peptides derived from them. Four proteases—papain, chymotrypsin, alkaline protease, and acid protease—were used to hydrolyze walnut proteins, and the degree of hydrolysis of the resulting hydrolysates was evaluated. The study focused on alkaline protease treatment at varying hydrolysis durations (2, 4, and 6 h), examining the degree of hydrolysis, yield, molecular weight distribution, bitterness response value, and amino acid composition of the hydrolysates. Low-bitterness antioxidant peptides were subsequently identified from the hydrolysates with reduced bitterness. Results showed that alkaline protease effectively hydrolyzed walnut proteins, achieving the highest degree of hydrolysis (55.60%±0.46%) and yield (48.86%±0.99%) after 6 h. As hydrolysis time increased, the proportion of high molecular weight components decreased, while that of low molecular weight components increased. The hydrolysate obtained after 4 h of hydrolysis exhibited the lowest bitterness response value, characterized by minimal proportions of hydrophobic and bitter amino acids in its composition, and displayed significant antioxidant activity. Two non-bitter peptide sequences, YWL and FFL, were identified from the 4 h hydrolysate. Molecular docking analysis indicated that these peptides could effectively bind to the Keap1 protein through hydrogen bonding and hydrophobic interactions, thereby exerting antioxidant effects. This study provides a theoretical foundation for the development of high-quality, low-bitterness walnut-derived antioxidant peptides, offering valuable insights for their potential applications in functional foods and nutraceuticals.