Marine mussel peptide hydrolysate-zinc chelates: Structural characterization and enhanced zinc bioaccessibility

As an important trace element, zinc plays a key role in maintaining normal physiological functions and promoting human health. However, zinc deficiency is prevalent worldwide due to its low bioavailability and poor absorption. In this study, peptides with specific zinc-binding capacity was isolated from mussel hydrolysates, and the potential health benefits of marine peptide-zinc chelates were evaluated through cellular and simulated in vitro uptake studies. A mussel ( Mytilus edulis Linnaeus) protein hydrolysate-zinc complex (MPH-Zn) was prepared under optimized conditions: pH 7.5, 50°C, 60 min, peptide concentration 60 mg/mL, peptide-to-ZnSO 4 ·7H 2 O ratio of 6:1, and 5 volumes of ethanol. The structural features of the chelate were characterized, and its effect on zinc bioaccessibility was examined. Results showed that carboxyl, carbonyl, and amino groups associated with charged amino acid residues were the main zinc-binding sites. Chelation of zinc ions with mussel peptide induced intramolecular and intermolecular folding and aggregation, leading to the formation of homogeneous MPH-Zn clusters. Furthermore, the MPH-Zn chelates markedly enhanced zinc solubility, particularly by resisting precipitation in the neutral pH of the intestine during simulated gastrointestinal digestion. These findings may provide a theoretical basis for developing novel zinc supplements and support the high-value utilization of mussel protein resources. • Developed MPH-Zn under optimized conditions (peptide 60 mg/mL, peptide/Zn = 6:1). • Multi-site chelation enables MPH-Zn to reach a high Zn 2+ chelation rate of 96.24%. • MPH-Zn promotes Zn 2+ uptake in intestinal Caco-2 cells. • MPH-Zn prevents intestinal precipitation, maintaining 98.89% Zn solubility.