Abstract: Objective: To investigate the effect of calcium, magnesium and potassium salts on the properties of coix seed starch-myofibrillar protein (CSS-MP) composite gel with low sodium content. Methods: Based on the results of previous research, the effects of partial substitution of NaCl by CaCl2, MgCl2 or KCl on the gel strength, water holding capacity (WHC), rheological properties, surface hydrophobicity, sulfhydryl group content, gel microstructure and sensory evaluation of CSS-MP composite gel were investigated. Results: The texture and rheological properties of the CaCl2 substitution group were better than those of the control group (3% NaCl), and the WHC and whiteness of the KCl substitution group were not significantly different from those of the control group, but the gel strength was decreased by MgCl2 or KCl substitution. The total sulfhydryl content of the CaCl2 and MgCl2 replacement groups was significantly lower than that of the control group, and the surface hydrophobicity of the CaCl2 replacement group was significantly higher than that of the other three groups. The addition of MgCl2 promoted the formation of hydrogen bonds, enhanced the hydrophobic interaction, while CaCl2 substitution had the opposite effect. In terms of sensory properties, the substitution of 1.0% CaCl2 and 0.5% MgCl2 could attain a saltiness perception similar to 3% NaCl. However, the comprehensive sensory score showed that the substitution of the three chlorine salts caused no significant difference in sensory properties of CSS-MP composite gel. Conclusion: Calcium, magnesium and potassium salts can improve the properties of CSS-MP composite gel in different degrees. The results of this study lay a theoretical foundation for the development of low-sodium composite surimi gel products.

Key words: myofibrillar protein; chlorine salt replacement; low sodium salt; composite gel; coix seed starch