Sodium selenite synergistic strategy based on myosin structural modification: Achieving soft selenium-enriched gel of large Yellow croaker surimi

This study elucidates a sodium selenite (Na₂SeO₃)-mediated strategy based on myosin structural modification to produce a soft selenium-enriched gel of large yellow croaker surimi. Experimental results provide compelling evidence that the incorporation of 10 mg/kg Na₂SeO₃ into the gel leads to a significant textural improvements: hardness decreases by 12.32%, chewiness by 10.62%, and gumminess by 12.41% (P < 0.05), rendering the surimi more conducive to swallowing. With increasing Na₂SeO₃ concentrations, gel strength exhibits a marked downward trend, which is attributed to Na₂SeO₃-myosin interactions. The processed surimi develops a softer, more dispersed, and moister "fine consistency" texture, conforming to IDDSI Level 5 standards (soft and cohesive, requiring minimal chewing). Mechanistic investigations reveal that Na₂SeO₃ induces static quenching and forms a stable binding with myosin, triggering secondary structural changes: the α-helix content decreases from 59.50% to 57.24%, while the β-sheet content increased from 16.17% to 17.90%, thereby altering protein aggregation behavior. This binding process is spontaneous, primarily driven by electrostatic interaction and hydrogen bonds. Molecular-level evidence confirms that Na₂SeO₃ possesses a narrow frontier orbital energy gap (3.51 eV) and strong molecular docking affinity for myosin (binding energy: -32.58 kcal/mol), enabling specific non-covalent interactions with this motor protein. This study has developed a soft surimi-based product that simultaneously achieves selenium nutritional fortification and texture improvement, thereby providing a theoretical foundation for the research and development of specialized foods for patients with dysphagia.