Structure and properties of iron-chelated peptides from chicken blood hemoglobin hydrolysates

• Arboxyl oxygen, carbonyl oxygen, and amino nitrogen were involved in chelation of CHH. • Chelation significantly improved the thermal stability of CHH. • The bioavailability of CHH-Fe was higher than FeSO4. • CHH-Fe had antioxidant activity with supplement iron function. This study aimed to develop a novel iron-chelated peptide complex (CHH–Fe) from chicken hemoglobin with better iron solubility and bioavailability compared to conventional iron sources. The structural properties, antioxidant activity, and iron bioavailability of CHH–Fe were systematically evaluated using spectroscopic techniques, stability assays, antioxidant tests, as well as in vitro digestion and Caco-2 monolayer cell models. The results of FTIR indicated that hydroxyl, carboxyl, and amidogen of the chicken hemoglobin peptides were involved in chelation. Chelation significantly modifies the microstructure of the complex. Particle size analysis revealed that the chelate exhibits improved dispersibility, while thermodynamic property analysis demonstrated its enhanced thermal stability. Both the chicken hemoglobin peptides and CHH-Fe demonstrated dose-dependent antioxidant activities; however, at equivalent concentrations, CHH-Fe exhibited significantly stronger antioxidant effects, with scavenging rates of 84.82% (DPPH) and 91.72% (ABTS) at 0.9 mg/mL. CHH-Fe exhibited superior iron solubility to FeSO 4 (56.59% vs. 14.65% at pH 9) and greater stability during intestinal digestion. Furthermore, in a Caco-2 cell monolayer model, CHH-Fe exhibited significantly enhanced iron bioavailability. This study demonstrates that chicken blood can be utilized as a sustainable raw material for the of highly bioavailable iron supplements.