Thermal stability and gel-forming ability of shark muscle as related to ionic strength

Thermal stability and gel-forming ability of silvertip, hammer-head and thresher shark as affected by ionic strength were investigated. Low temperature endothermic peaks (LTEP, between 30 and 44 degrees C) were observed in differential scanning calorimetric (DSC) thermograms of the shark muscles and surimi samples. Increases in ionic strength reduced the thermal stability of surimi as shown by depression of transition temperature, denaturation enthalpies and LTEP. Although gel strength of heat-treated surimi increased with increasing NaCl concentration, the three species had different sensitivities to ionic strength. The highest NaCl-induced gel-forming ability of surimi was achieved at 0.5M salt concentration for silvertip and thresher; at 1.0M for hammer-head shark.