Short-chain polypeptides modulate ice crystallization to enhance cryoprotection of Saurida tumbil-derived fish balls

Short-chain polypeptides ( SCPs ) derived from bovine skin were investigated as natural antifreeze in Saurida tumbil -derived fish balls ( STFB ) during frozen storage. SCPs can inhibit ice crystal growth, reducing surface cracking of STFB at −20 °C. An optimal addition of 10.0 g/kg lowered cooking loss by 10.8% compared with 20.0 g/kg-added samples. It maintained springiness (8.5% reduction), and stabilized color (11.8% b* reduction) compared with none SCPs -added samples, reflecting balanced texture and palatability. Rheological results showed that increasing SCPs decreased G′ , G″ , and η* , indicating partial loosening of the gel network due to disruption of protein-protein hydrophobic interactions and disulfide bonds, with enhanced frequency dependence. Excess SCPs (≥ 15.0 g/kg) could weaken the gel network by competing with protein-protein hydrophobic interactions and disulfide bonds, as inferred from reductions in G′ , G″ , K f , and G′ 0 , leading to increased n′ . LF-NMR analysis showed that SCPs promote the migration of bound water to immobilized states in STFB by competitively binding hydrophilic sites, evidenced by rightward T 21 shifts and reduced A 21 proportions, while mitigating ice crystal-induced mechanical damage and bound water loss during frozen storage through adsorption-inhibition and thermal hysteresis mechanisms. Therefore, SCPs represent an effective cryoprotectant for surimi products with high sensory neutrality. • SCPs inhibited ice crystal growth, reducing surface cracking in STFB • 1.0% SCPs addition delayed discoloration with minimal quality loss • Excess SCPs (>1.5%) weakened gel network and texture integrity • LF-NMR showed SCPs improved water mobility and distribution • Sensory scores confirmed 1.0% SCPs balanced quality and acceptability