Improvement of Frozen Shrimp Surimi Quality by Gelatin Prepared through Hot-pressing of Sturgeon Cartilage and Its Effects on the Myofibrillar Protein

This study aimed to investigate the cryoprotective effect of gelatin prepared by hot-pressing sturgeon cartilage (SCG) on myofibrillar protein (MP) in shrimp surimi, with the aim of improving the quality stability of frozen shrimp surimi. In this study, different concentrations of SCG (0%, 0.5%, and 1.0% w/w) were added to shrimp surimi and compared with traditional commercial antifreeze (4% sucrose+4% sorbitol). Changes in minced shrimp quality and gel characteristics during a 60-day freezing period were systematically evaluated using sensory analysis, texture profile, colorimetry, water holding capacity, pH, TVB-N, TBARs, and protein content. Concurrently, MP structure and functionality, relating to shrimp integrity differences, were analyzed by determining total sulfhydryl, active sulfhydryl, carbonyl, and disulfide bond content, alongside circular dichroism and endogenous fluorescence spectroscopy. The results showed that the addition of SCG improved the elasticity and gel strength of minced shrimp, optimized sensory attributes, and enhanced the water holding capacity. Meanwhile, SCG slowed down the oxidation of MP during freezing and storage, reducing the carbonyl content of the oxidation marker and increasing the content of antioxidant-related total and active sulfhydryl groups. At the 0.5% addition level, SCG showed the best effect on the improvement of gel properties and MP oxidation inhibition of minced shrimp, even better than traditional commercial antifreeze. After 60 d of freezing, the gel of minced shrimp with 0.5% SCG increased 43.30% and 14.36% in elasticity and gel strength, increased by 12.73% in water-holding capacity, 12.90% and 34.39% in total MP sulfhydryl group and active sulfhydryl group content, respectively, decreased 27.08% in the carbonyl group content, and increased by 21.21% (P<0.05) in Ca²⁺-ATPase activity. In conclusion, the addition of 0.5% SCG had an antifreezing effect comparable to that of commercial antifreeze and was able to effectively slow down the protein denaturation of minced shrimp during the freezing process and maintain its good quality.