食盐添加量对预制鲈鱼冷藏保鲜及热加工特性的影响

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

为研究不同食盐添加量（0～2.0%）对鲈鱼冷藏保鲜及热加工特性的影响,采用差示扫描量热法,研究鲈鱼鱼肉的含水率、冰点、变性温度、热焓和比热容等热特性并进行分析。研究发现,预制鲈鱼的冰点和含水率随食盐添加量的增加而逐渐降低;加热温度50℃附近吸热峰的起始温度、终止温度及变性热焓随食盐添加量的增加均逐渐降低;70℃附近吸热峰仅明显存在于新鲜鲈鱼样品中,其他食盐添加量条件下70℃附近吸热峰消失;鲈鱼鱼肉的比热容随食盐添加量的增加未呈现明显的变化趋势（P〉0.05）,当鱼肉处于冻结状态、肌球蛋白及肌动蛋白处于变性状态时,2.0%食盐添加量鲈鱼的比热容最高,当鱼肉处于未冻结状态时,1.0%食盐添加量鲈鱼的比热容最高。研究表明：在不同食盐添加量（0～2.0%）条件下,随着食盐添加量的增多,鲈鱼冰点和含水率逐渐下降,肌球蛋白变性温度向低温方向移动,峰高逐渐降低,变性热焓逐渐下降,肌动蛋白峰消失;添加食盐的鲈鱼比热容变化皆小于新鲜鲈鱼（除1.0%食盐添加量）（P〈0.05）;在不同食盐添加量（0～2.0%）条件下,未冻结鱼肉的比热容高于冻结鱼肉（P〈0.05）,加工后的鱼肉的比热容高于未加工的鱼肉（P〈0.05）。研究结果为预制鲈鱼热加工和低温贮藏的品质控制提供参考。

The study was to investigate the refrigeration preservation and the hot working properties of muscle from weevers with different additive sodium chloride（NaC l） 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 Na Cl content increased; the original temperature, the end temperature and the denaturation enthalpy of decalescence peak around 50 ℃ all decreased with the increase of the NaC l 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 NaC l contents. There was no obvious variation trend of the specific heat capacity when the NaC l content increased（P〈0.05）. The specific heat capacity of the precooked weever with 2.0% additive NaC l 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 NaC l 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 NaC l contents（0-2.0%）, when the NaC l 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 NaC l was less than that of fresh weevers（except that of the weevers with 1.0% additive NaC l content）（P〈0.05）; with the different additive NaC l 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.