Characterization of Oyster Protein Hydrolysate–Iron Complexes and their In Vivo Protective Effects against Iron Deficiency-Induced Symptoms in Mice

Iron is one of the trace mineral elements, and iron deficiency is a common phenomenon that negatively influences human health. Food-derived iron supplements were considered excellent candidates for improving this syndrome. In this work, oyster-protein hydrolysates (OPH) and ferrous chloride successfully formed the OPH–Fe complex (6 mg/mL, 40 °C, 30 min), where the main binding sites involved were the carboxyl and amino groups. The OPH–Fe complex showed no obvious changes in the secondary structure, while the iron changed the morphological appearance and also showed fluorescence quenching, an ultraviolet shift, and an increase in size distribution. The OPH–Fe complex showed better dynamic absorption of iron (64.11 μmol/L) than ferrous sulfate (46.90 μmol/L), and the medium dose had better protective effects against iron-deficiency anemia in vivo. Three representative peptides (DGKGKIPEE, FAGDDAPRA, and VLDSGDGVTH) that were absorbed intact were identified. This experiment provided a theoretical foundation for further study of the digestion and absorption of the OPH–Fe complex.