Mechanistic insight into polysaccharides and ultrasound synergistic enhancement of the quality of low-salt surimi gels.

To address gel network deficiencies in low-salt surimi caused by the poor solubility of myofibrillar proteins, a strategy combining different polysaccharides (carrageenan, chitosan, or curdlan) with ultrasound-assisted heating at 40 °C (US40) was investigated to elucidate their structure-function relationships. A synergistic enhancement was achieved when polysaccharides were combined with US40, resulting in further increases in gel strength, textural properties, and a reduction in cooking loss. Microstructural analysis revealed the development of denser and more homogeneous gel networks. The underlying mechanism involved US40-induced MP structural unfolding and polysaccharide chain extension, which promoted molecular interactions, as supported by altered protein aggregation patterns, the migration of tyrosine residues into hydrophobic microenvironments, and the enhancement of intermolecular forces, particularly hydrophobic interactions and disulfide bonds. The enhancement mechanism was dependent on polysaccharide type, with the combination of carrageenan and US40 demonstrating the most pronounced improvements. These findings provide theoretical foundations for developing high-quality low-salt surimi products.