Understanding the role of CaCl2 in salt substitute for low-salt and high-quality surimi products

Salt substitute has been widely used to prepare low-salt foods due to potential health benefits, though the role of CaCl₂ in salt substitute and its unique impacts on food quality have been rarely investigated. In this study, comprehensive research has been conducted to elucidate the effects of replacing NaCl with varying concentrations of CaCl₂ on the surimi gel characteristics. The introduction of CaCl₂ interacted with surimi proteins differently from NaCl, thus leading to difference in protein aggregation behaviors and surimi gel properties. It has been found that a proper proportion of CaCl₂ for NaCl substitution could create salt bridges between surimi proteins more effectively, resulting in an ordered, smooth and dense gel network with an increased water holding capacity (WHC) and improved gel strength. Furthermore, TGase activated by Ca²⁺ boosted the formation of ε-(γ-glutamyl) lysine bonds, which cross-linked surimi proteins to form a firm gel with a better three-dimensional structure. However, replacing NaCl with excessive amount of CaCl₂ as divalent salts induced more serious protein aggregation, leading to water loss and gel properties deterioration. More specially, replacing NaCl with CaCl₂ at 50% showed the best performance, as evidenced by the most abundant disulfide bonds and hydrophobic interactions, highest hardness and chewiness, and greatest storage modulus. This study provided new insights on developing high-quality surimi gels with significantly reduced salt concentration and improved gel characteristics.