Allicin-mediated protection of myofibrillar proteins in refrigerated mandarin fish (Siniperca chuatsi): Molecular interactions with endogenous proteases and inhibition of protein degradation.

Endogenous proteases accelerate myofibrillar protein (MP) degradation and quality loss in fish. This study investigated allicin's protective effects on refrigerated mandarin fish (Siniperca chuatsi). Allicin treatment significantly inhibited cathepsin B, cathepsin L, and calpain activities and reduced MP degradation, leading to lower MFI values and slower accumulation of TCA-soluble peptides. Molecular docking and enzyme assays demonstrated that allicin binds to key catalytic residues of these endogenous proteases, suggesting a multi-target inhibitory mechanism. SDS-PAGE and histological staining further confirmed slower degradation of MPs and collagen, along with improved maintenance of muscle fiber integrity. CD and intrinsic fluorescence confirmed allicin attenuated α-helix loss, delayed tryptophan exposure, and stabilized sulfhydryl groups, indicating protection against oxidative and conformational damage. Overall, allicin inhibits endogenous proteases and preserves protein conformation, highlighting its potential as a natural preservative to improve fish storage quality.