Acid-induced gel formation of silver carp (Hypophthalmichthys molitrix) myofibrils as affected by salt concentration

Abstract

The influence of salt concentration on acid-induced gel formation and gel properties of silver carp myofibrils was investigated. Results showed that silver carp myofibrils were slightly soluble regardless of salt concentration in the presence of D-gluconic acid-d-lactone (GDL). The increase of myofibrils solubility in the absence of GDL was mainly caused by the dissociation of myosin and actin, as evidenced by SDSPAGE. Myosin and actin were the major protein components involved in acid-induced aggregation of silver carp myofibrils. Ca2+-ATPase activity and surface reactive sulphydryl (SH) contents of myofibrils with GDL addition were much lower than those in the absence of GDL. Significant decrease in total SH content of silver carp myofibrils in the present of GDL at salt concentration of 0.3 mol/L NaCl was observed, suggesting the contribution of disulphide bonds to the acid-induced gel formation. The gel properties of acidinduced silver carp myofibril gel were highly dependent upon salt concentration, and acidified myofibril gel with high gel strength could be obtained with addition of 1.7% - 2% NaCl.