Improvement of stability and antioxidant capacity of peptide - iron complexes by sonication

In the present study, peptide‑iron complexes derived from Dictyophora rubrovolvata volva (U-VP-Fe) were prepared using ultrasonication. Their structures, interactions, stability and antioxidant activity were systematically characterised. The production conditions optimized by orthogonal tests were as follows: ultrasonic power 90 W, peptide concentration 4 %, mass ratio of peptide/FeCl₂ 1:1, and pH 4. Under such conditions, the iron binding capacity could reach 66.35 mg/g. Fluorescence spectral analyses revealed that hydrophobic forces dominated the binding to Fe²⁺, and the binding process was endothermic and spontaneous. Morphological analyses showed that U-VP-Fe featured a dense and smooth surface with significantly improved surface hydrophobicity and particle size. Stability analyses suggested that U-VP-Fe exhibited better resistance to high temperature, pH and gastrointestinal digestion than the hydrothermal control (C-VP-Fe). Antioxidant assays demonstrated that U-VP-Fe presented superior antioxidant capacity than C-VP-Fe. The findings lay the theoretical foundation for applying ultrasound method to produce peptide‑iron complexes as novel iron supplements.