碱性蛋白酶对鲢肌原纤维蛋白凝胶特性的影响
Effect of alkali protease on gel properties of sliver carp myofibrillar protein

以鲢肌原纤维蛋白为研究对象，通过测定碱性蛋白酶处理前后鲢肌原纤维的降解率、巯基含量、表面疏水性、Ca2+ ATPase活性、凝胶特性等的变化， 研究在不同的贮藏条件下（25℃和4℃）碱性蛋白酶对鲢鱼肉中肌原纤维蛋白的降解情况及凝胶特性的影响。结果发现，经过碱性蛋白酶处理后，在不同温度下，鲢肌原纤维蛋白的降解率均随着时间的延长而增大；表面疏水性、Ca2+ ATPase活性、总巯基及活性巯基含量均先增高后降低；在反应温度25℃、酶解时间2.0 h以及反应温度4℃、酶解时间2.5 h处理条件下，鲢肌原纤维蛋白的表面疏水性、总巯基及活性巯基含量均达到最高值；在反应温度25℃和4℃下，酶解时间0.5 h 时， Ca2+ ATPase活性达到最高值；蛋白凝胶的持水力与凝胶强度均呈下降趋势；凝胶白度值先降低后增加；扫描电镜结果显示，碱性蛋白酶对鲢肌原纤维蛋白凝胶网络结构产生了一定的破坏作用。
Myofibrillar proteins were prepared and stored at 25℃ and 4℃. The effects of alkaline protease on the degradation and gel properties of myofibrillar protein were studied using the degradation rate,sulfhydryl content,surface hydrophobicity,Ca2+ ATPase activity and gel properties as indexes. For the myofibrillar proteins with alkaline protease,the degradation rate increased with prolonging storage time at different temperatures. The surface hydrophobicity,Ca2+ ATPase activity,contents of total and active sulfhydryl groups increased followed by a decrease,and reached the maximum under the conditions of 25℃ and 2.0 h,or 4℃ and 2.5 h. In addition,the Ca2+ ATPase activity reached the maximum at 0.5 h. As the storage time prolonged,the water holding capacity and gel strength decreased,and the whiteness decreased followed by an increase. The SEM showed that the protease destroyed the three dimensional network structure of the gel to an extent.