Effect of Phosphate in Compound Cryoprotectant on Antifreeze Effect of Acanthopagrus latus

In order to improve the quality of frozen bream and use it to produce high-quality surimi, the effect of phosphate ratio in compound cryoprotectant on frozen Acanthopagrus latus was studied. The freezing point and latent heat of fish were measured by differential scanning calorimeter. The ratio of phosphates in compound cryoprotectant was optimized by orthogonal experiment based on the results of single-factor experiment. The results of orthogonal experiment showed that when 3% sodium pyrophosphate, 3% sodium tripolyphosphate and 1% sodium hexametaphosphate were added into the compound cryoprotectant, the freezing point and latent heat of fish decreased to −2.3 ℃ and 147.2 J/g respectively. Acanthopagrus latus were treated with the optimized compound cryoprotectant and frozenat −18 ℃ for 30 days, the protein solubility of the fish increased by 8.1%, and the activities of Ca2+-ATPase, Mg2+-ATPase and Mg2+-Ca2+-ATPase increased by 75.6%, 26.9% and 113.7% respectively, compared with the unsoaking group. The activities of Ca2+-ATPase and Mg2+-Ca2+-ATPase could reach 98.6% and 84.5% of those in fresh fish. The breaking force and breaking distance of the surimi prepared by fish of the soaking group were 84.9% and 96.3% of those in surimi prepared by fresh fish respectively, and the gel strength was more similar to the surimi prepared by fresh fish compared with the unsoaking group. In conclusion, the optimized compound cryoprotectant could effectively reduce the denaturation of Acanthopagrus latus proteins during frozen storage.