Phosphorylated Salmon bone polypeptides: enhancing stability and antimicrobial activity through zinc chelation

Salmon bones, a marine waste, have bioactive potential. Salmon bone peptides (SBPs) were phosphorylated at different pH to form P-SBPs, whose structure and that of their zinc chelates (P-SBPs-Zn) were analyzed <i>via</i> Fourier-transform infrared spectroscopy, fluorescence spectroscopy and CD spectrum. Among the pH-modified variants, phosphopeptide‑zinc chelates at pH 4 (P-SBPs4-Zn) exhibited the best solubility and highest zinc chelating property, with a zinc content of 86.15 ± 0.47 mg/g. The stability and digestibility were tested under simulated gastrointestinal conditions (adults/elderly, dietary components). P-SBPs4-Zn demonstrated optimal stability and digestibility. After evaluation the antibacterial activity, P-SBPs4-Zn exhibited significant antibacterial effects against <i>Escherichia coli</i> and <i>Staphylococcus aureus</i> through mechanisms involving membrane disruption. The safety assessment using Caco-2 and RAW 264.7 cells confirmed its biocompatibility, supporting its suitability for oral application. This supports its use as an efficient, stable, antibacterial zinc supplement for food processing.