Effect of NaCl replacement by other salt mixtures on myofibrillar proteins: Underlining protein structure, gel formation, and chewing properties

The protein structure, gel changes, and chewing properties of low-sodium myofibrillar protein (MP) prepared by compound chloride salts (KCl/MgCl₂, KCl/CaCl₂, and KCl/MgCl₂/CaCl₂) and different substitution degrees (10%, 25%, and 40%) at same ionic strength (0.6 M) were investigated. The results revealed that the low-sodium MP gels containing CaCl₂ manifested more liquid loss and less moisture content accompanied by obvious morphological shrinkage, while KCl/MgCl₂ contributed to the gel juiciness. At high substitution degree of 40%, KCl/CaCl₂ substitution rendered the gel with dense structure and highest strength, but worse water retention capacity. Using other compound chloride salts influenced the chewing efficiency, and CaCl₂ substitution made the gel relatively hard to chew. The inhomogeneous structure accompanied by cluster blocks in KCl/CaCl₂-substituted MP gel accelerated the overall fracture rate. During heating process, more proteins in CaCl₂-substituted MP did not participate in gel formation, intervening the final gel properties. The chloride salt mixtures containing MgCl₂, rather than CaCl₂, avoided or alleviated the liquid loss and shrinkage of low-sodium MP gel within the substitution degree of 10%-40%, and substitution degree not exceeding 25% was more reasonable for the controlled qualities.