New insights into the cryoprotective mechanism of antifreeze peptides for surimi: Dual regulation of ice crystals and myosin.

This study investigated the cryoprotective effects and mechanisms from Evynnis japonica scales antifreeze peptides (Ej-AFP) on myosin during freeze-thaw cycles. Ej-AFP was evaluated through biochemical assays, multispectral analyses, and molecular docking. Results showed that Ej-AFP inhibited myosin oxidation and aggregation, maintaining Ca2+-ATPase activity at 76.90 %, reducing carbonyl formation by 40.76 %, and preserving total sulfhydryl content at 79.51 %, indicating enhanced structural integrity. Spectroscopic analyses revealed that Ej-AFP stabilized the microenvironment of tryptophan and tyrosine residues and maintained the secondary structure of myosin. Molecular docking demonstrated that representative peptides (GGAFP and NKAFP) interact with myosin through hydrogen bonds, salt bridges, and van der Waals forces, thereby stabilizing its conformation. By combining ice recrystallization inhibition with direct protein stabilization, Ej-AFP provided superior protection at lower concentrations than conventional sucrose-sorbitol mixtures, highlighting its potential as a safe, food-grade cryoprotectant for improving the quality and stability of frozen surimi products.