Effects of high-intensity ultrasound on aggregate states of alkaline-extracted silver carp protein: Correlating mechanisms of structural disruption and functional enhancement

This study systematically investigated the mechanism of high-intensity ultrasound (HIU, 400 W) modification on alkaline-extracted silver carp protein (AP). Short-time HIU treatment (3–10 min) effectively dissociated AP aggregates and reduced particle size. Structurally, HIU induced unfolding of the α -helical structure in the myosin tail, promoting exposure of hydrophobic groups and active sulfhydryl residues, thereby increasing solubility to 85%. Functionally, emulsifying activity index (EAI) and emulsifying stability index (ESI) increased by 60.4% and 14.3%, respectively; gel strength enhanced nearly fourfold, and water-holding capacity (WHC) improved by approximately 95%. This study reveals the synergistic behavior between alkaline extraction and HIU: the previous conformational loosening during alkaline treatment offers the “preliminary space” for the subsequent “deagglomeration-activation” action of ultrasound to restructure silver carp protein from aggregated states to molecular level, which offers new technical route and theoretical support to obtain highly functional fish protein products.