Effect of different additive NaCl content on refrigeration freshness and thermal properties of precooked weevers

Abstract: The study was to investigate the refrigeration preservation and the hot working properties of muscle from weevers with different additive sodium chloride (NaCl) content (0-2.0%) by differential scanning calorimetry (DSC), and the analysis of thermal properties of the weevers included the moisture content, the freezing point, the denaturation temperature, the denaturation enthalpy, the specific heat capacity, and so on. Results showed that the freezing point and the moisture content both decreased gradually when the NaCl content increased; the original temperature, the end temperature and the denaturation enthalpy of decalescence peak around 50 ℃ all decreased with the increase of the NaCl content; the decalescence peak around 70 ℃ only existed in the fresh weever samples evidently and it could not be found under the condition of other additive NaCl contents. There was no obvious variation trend of the specific heat capacity when the NaCl content increased (P<0.05). The specific heat capacity of the precooked weever with 2.0% additive NaCl content was the highest in the condition of the precooked weever's frozen status, the myosin's denatured (and actin's non-denatured) status or actin's denatured status; the specific heat capacity of the precooked weever with 1.0% additive NaCl content was the highest when the precooked weever was in the unfrozen status. As demonstrated by the research, among these 5 kinds of different additive NaCl contents (0-2.0%), when the NaCl content increased, the freezing point and the moisture content of weever both gradually decreased, the denaturation temperature of myosin moved toward the direction of lower temperature, the denaturation enthalpy of myosin decreased, which could reflect the decrease of the height of myosin's decalescence peak, and meanwhile the decalescence peak of actin disappeared; the change of specific heat capacity of the weevers with the additive NaCl was less than that of fresh weevers (except that of the weevers with 1.0% additive NaCl content) (P<0.05); with the different additive NaCl content (0-2.0%), the specific heat capacity of unfrozen fishes was higher than that of frozen fishes (P<0.05) and the specific heat capacity under processed status was higher than that under unprocessed status (P<0.05). The research results can provide the reliable reference for the hot working and the cryopreservation of the precooked weevers.