Cryoprotective Effect and Mechanism of Fish Scale Gelatin on Surimi Myofibrillar Proteins

The cryoprotective effects of adding different concentrations (0.5%, 1% and 2% (m/m)) of fish scale gelatin on frozen-thawed surimi were investigated in terms of the molecular structure myofibrillar proteins and gel properties. After eight cycles of freezing and thawing, the solubility, sulfhydryl content and Ca²⁺-ATPase activity of myofibrillar proteins with 1% fish scale gelatin decreased by 49.2%, 17.4% and 31.2%, less than those in the control group without fish scale gelatin (69.8%, 26.6%, and 49.4%), respectively. The increase in surface hydrophobicity and carbonyl content was inhibited more by 1% fish scale gelatin (42.7% and 229.9%) than by commercial anti-freezer (159.4%). Meanwhile, adding fish scale gelatin obviously inhibited the deterioration of the rheological properties and gel properties of surimi during freeze-thaw cycles. Furthermore, sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) and differential scanning calorimetry (DSC) indicated that fish scale gelatin could inhibit myofibrillar protein degradation by interacting hydrophobically with the side chain of myofibrillar proteins as well as inhibiting ice crystal growth.