Effect of CaCl₂ Substitution of NaCl Combined with Sodium Alginate on the Gelling Properties of Shrimp Surimi

In order to reduce the content of NaCl in shrimp surimi while improving its gelation properties, the effects of different levels of NaCl substitution with CaCl₂ combined with sodium alginate (SA) on the protein structure and gelation properties of shrimp surimi as characterized by 3D printing characteristics, gel strength, water-holding capacity (WHC), texture properties, rheological properties, protein secondary structure, and and molecular chemical forces were investigated under the same ionic strength. The results showed that the hardness, gel strength, β-sheet content, and hydrogen bond content of shrimp surimi increased significantly (P < 0.05) with increasing level of CaCl₂ substitution, while WHC of surimi gels showed a gradual decreasing trend (P < 0.05), and the 3D printing supportability became worse. The high concentration of Ca²⁺ (0.5%) caused excessive protein aggregation, which was unfavorable to the formation of a good gel structure, thereby leading to a decrease in WHC. The addition of SA improved the WHC of shrimp surimi gels, and the results of protein secondary structure and chemical force showed that substitution of CaCl₂ had no significant effect on the protein secondary structure of shrimp surimi, but increased the hydrogen bond content and hydrophobic interaction of the surimi gels, promoted the formation of gel networks, and improved the quality of the surimi gels. The above results indicate that incorporation of CaCl₂ combined with SA can improve the gel characteristics and quality of shrimp surimi, which provides a reference for the development of low-salt shrimp surimi products.