Triple gel enhancement, antioxidant and cryoprotective effects of the enzyme-assisted extracted surimi by-product proteins on unwashed silver carp surimi.

The limited gel-forming ability and poor storage stability of unwashed surimi hinder its large-scale industrial adoption, requiring targeted solutions. This study aimed to investigate the gel enhancement, antioxidant and cryoprotective effects of enzyme-assisted extracted surimi by-product proteins (EAE-SBPs) on unwashed surimi. The EAE-SBPs were characterized and then incorporated into surimi system to evaluate their influences on the quality of freeze-thaw (FT) treated raw surimi or surimi gel. The results revealed that EAE-SBPs exhibited triple cryoprotective activity (54.90 % yeast cell viability), antioxidant capacity (58.72 % DPPH radical scavenging rate), and gel-strengthening capability. Compared to controls, the raw surimi containing EAE-SBPs demonstrated significantly retarded reduction in protein Ca-ATPase activities, and mitigated increase in TBARS levels and protein carbonyl contents during FT process (p < 0.05). After 6 FT cycles, a significantly higher (p < 0.05) gel strength, water holding capacity, and structural integrity of gel network, as well as a more restricted water migration and ice crystal growth, were observed in the EAE-SBPs-added surimi gels than those in controls. These findings offer a knowledge on severing EAE-SBPs as a concurrent cryoprotectant, antioxidant and gel enhancer in unwashed surimi processing, ultimately contributing to the production of unwashed surimi with enhanced quality.