Preparation, Structure Sharacterization and Stability of Adlay Bran Peptide-iron Chelate

In order to fully utilize adlay bran resources and reduce the waste of protein resources, we prepared adlay bran peptides through alkaline protease hydrolysis of adlay bran protein, which was extracted from adlay bran. The preparation of adlay bran peptides - iron chelate (ABP-Fe) was optimized based on univariate analysis and orthogonal tests. The ABP-Fe was characterized using UV spectroscopy, Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), and atomic force microscopy (AFM). Also, its stability was explored and its Fe²⁺ release characteristics were investigated through in vitro gastrointestinal digestion simulations. The results showed that the optimized conditions for the preparation of ABP-Fe were pH5.0, peptide-to-iron mass ratio 3:1, reaction temperature 40 ℃ and reaction time 20 min. Under the optimized conditions, the chelation rate of Fe²⁺ in the ABP-Fe reached 76.33%. Characterization using UV and FTIR spectroscopy indicate that Fe²⁺ chelates with the carboxyl oxygen and amino nitrogen on the ABP peptide chains to form a new substance. Characterization using SEM and AFM reveal that the adlay bran peptides transform from smooth fragments into rough particles after chelation with Fe²⁺, with significant morphological differences. Additionally, the ABP-Fe exhibited good stability under varying pH and temperatures, and its Fe²⁺ release rate was higher than that of ferrous sulfate in the in vitro gastrointestinal digestion simulations. The as-prepared adlay bran peptide-derived iron supplement exhibited excellent chelation capability, good stability, and high release rate. This study provides insights for efficient utilization of adlay processing by-products and development of novel dietary iron supplements.