Study on Preparation Process, Antioxidant Activity and Stability of Maillard Reaction Products from Wodyetia bifurcata Pulp

To explore novel antioxidants, this study prepared Maillard reaction products（WBP-MRPs）and non-Maillard reaction control products（WBP-NMRPs）from Wodyetia bifurcata pulp. The differences between the two were clarified through in vitro antioxidant activity analysis, and high-activity WBP-MRPs were subsequently prepared. The Box-Behnken response surface methodology was employed to optimize the preparation process of WBP-MRPs using DPPH radical scavenging rate as the response indicator. Meanwhile, the application potential of WBP-MRPs was investigated from four aspect: in vitro simulated gastrointestinal digestion stability, the influence of metal ion, and tolerance to temperature and pH. The results showed that the DPPH radical scavenging capacity of WBP-MRPs was significantly superior to that of WBP-NMRPs（P＜0.01). When the sample concentration was 0.8 mg·mL⁻¹, the free radical scavenging rate of WBP-MRPs was approximately 3.78 times that of WBP-NMRPs, with a significant difference between the two. The optimal preparation process for WBP-MRPs obtained through response surface optimization was as follows: reaction temperature of 85°C, reaction time of 73 min, and reaction system pH of 8. Under these conditions, the DPPH radical scavenging rate of WBP-MRPs reached 80.60%. Further quantitative analysis of antioxidant activity characteristics indicated half-maximal inhibitory concentrations（IC₅₀）of WBP-MRPs against DPPH radicals, ABTS radicals and hydroxyl radicals were 14.10±2.39 μg·mL⁻¹, 9.58±1.01 mg·mL⁻¹, and 2.03±1.53 mg·mL⁻¹, respectively. Stability analysis demonstrated that after in vitro simulated gastrointestinal digestion, the antioxidant activity retention rate of WBP-MRPs was 61.24%. Among the tested metal ions, Ca²⁺, Cu²⁺, Zn²⁺, and Fe²⁺ could extremely significantly reduce on the antioxidant activity of WBP-MRPs（P＜0.01), while K⁺ had no significant effect on its antioxidant activity（P＞0.05). In addition, when the temperature was ≤ 80°C, the antioxidant activity of WBP-MRPs did not change significantly（P＞0.05); when the pH was ≤ 8, the antioxidant activity of WBP-MRPs also did not change significantly（P ＞ 0.05). This indicated that the temperature sensitivity threshold of WBP-MRPs was 80°C, and the pH sensitivity threshold was 8. In conclusion, WBP-MRPs prepared from W. bifurcata pulp exhibit favorable antioxidant activity and gastrointestinal digestion stability, but demonstrate weak tolerance to high temperature and alkaline environment（pH＞8). This research results can provide basic data for the development of antioxidant active substances based on the Maillard reaction, and offer new ideas and theoretical support for the high-value processing and utilization of W. bifurcata pulp.