Enzymatic Preparation of Wheat Bioactive Peptides and Their Antioxidant Properties

This study aimed to develop wheat-active peptides with enhanced antioxidant properties by identifying suitable enzymes and optimizing the hydrolysis conditions. Gluten was hydrolyzed using neutral protease, alkaline protease, and papain, and the optimal enzyme was selected based on DPPH radical scavenging efficiency. Further optimization of enzymatic conditions (time, temperature, and enzyme dosage) for the neutral proteases was conducted using response surface methodology. The molecular weight distribution was analyzed using high-performance liquid chromatography (HPLC), while the degree of hydrolysis and protein purity were assessed using the OPA and BCA methods. The antioxidant capacity was evaluated using DPPH, ABTS⁺ radical scavenging, hydroxyl radical scavenging, superoxide anion radical scavenging, and ORAC assays. The results indicated that the DPPH radical scavenging rates of peptides produced by neutral protease, alkaline protease, and papain were 90.17%, 71.88%, and 39.12%, respectively, indicating that neutral protease exhibited superior performance. Optimal conditions—3.36 hours of hydrolysis time, 53 ℃ temperature, and 10187.5 U/g enzyme dosage—yielded a maximum DPPH radical scavenging rate of 92.22%. Under these conditions, the sample exhibited a degree of hydrolysis of 11.53% and a protein purity of 85%, with over 62.12% of the peptides having a molecular weight below 1000 Da, displaying higher antioxidant activity. Additionally, the prepared wheat active peptides demonstrated exceptional antioxidant capabilities in ABTS⁺ radical scavenging (97.47%), hydroxyl radical scavenging (55.21%), superoxide anion radical scavenging (89.65%), and ORAC value (2.65 mmol Trolox/g). Notably, the hydroxyl and superoxide anion radical scavenging activities were significantly higher than those of the control group (P<0.05). Although the DPPH and ABTS⁺ radical scavenging rates were slightly lower than those of the controls, the ORAC values were not significantly different (P>0.05). These findings indicate that the optimized enzymatic process effectively enhances the antioxidant properties of active wheat peptides, providing a robust foundation for further development of functional food applications.