Preparation, characterization, and properties of wampee seed antioxidant peptides‐iron chelate

The chelation process of antioxidant peptides with iron was optimized by response surface methodology with iron chelation percentage as a response. The optimum process was chelation time of 38 min, chelation temperature of 31°C, chelation pH of 5.2, and peptides-to-iron mass ratio of 3.4:1. Scanning electron microscopy observation showed the chelate was a smooth and dense granular aggregate morphology. Fourier transform infrared spectroscopy analysis indicated the chelate's characteristic peaks shifted significantly compared with the antioxidant peptides. The α-helix and random coil contents decreased from the peptides of 60.86% to the chelate of 43.74%. However, the β-structure contents increased from the peptides of 39.14% to the chelate of 56.26%. The in vitro digestion test suggested the chelate had 97.37% bioaccessibility and 58.53% DPPH radical scavenging effect in gastric digestion. But those in intestinal digestion remained 50.02% and 41.02%, respectively. The chelate can be used as a new iron supplement. Novelty impact statement The preparation process of wampee seed antioxidant peptides-iron chelate was optimized by response surface methodology. Iron ions binding to the peptides was through carboxyl oxygen and amino nitrogen atoms. Chelate showed good antioxidant activity and bioaccessibility during gastrointestinal digestion.