竹荚鱼冻藏过程中肌肉品质与蛋白质理化性质的变化及其相关性分析

为探究竹荚鱼冻藏期间的新鲜度品质变化规律，本文以色泽、电导率、冰晶大小及形态、质构、K值、TBA值、拉曼光谱、总蛋白二级结构、肌原纤维蛋白巯基含量和Ca2+-ATPase活性等为指标，研究了真空包装（VP）和空气包装（AP）的竹荚鱼在?18 ℃冻藏90 d内的肌肉品质和肌肉蛋白质理化性质的变化。结果显示，随着冻藏时间的延长，VP、AP两组鱼肉样品的K值、L*值、白度值、TBA值均逐渐升高，其中K值冻藏90 d后分别增加了65.83%和66.44%；同时鱼肉中冰晶孔隙逐渐增大，a*值、b*值、硬度、咀嚼度、回复性则逐渐下降，内聚性和电导率呈现先升高后降低趋势。蛋白质理化测定结果显示，冻藏过程中，α-螺旋百分含量由63.28%分别降低到43.70%、41.91%，β-折叠、β-转角、无规则卷曲百分含量逐渐升高，肌原纤维蛋白的总巯基、活性巯基含量逐渐降低，Ca2+-ATPase活性分别下降了63.58%和72.52%。空气、真空两种包装方式对竹荚鱼冻藏期间的肌肉品质影响不大，对蛋白质生化特性有一定影响且真空包装略优于空气包装。由相关性分析可知，两组鱼肉样品的K值、色泽、TBA值、巯基含量、Ca2+-ATPase活性、总蛋白二级结构百分含量与冻藏时间之间、两两之间均显著相关（P<0.05）或极显著相关（P<0.01），可作为评价竹荚鱼冻藏过程中品质变化的有效指标。研究结果可为深入探究竹荚鱼的品质变化机理和生产实践中的货架期预测提供理论参考。

Changes of Trachurus japonicus Muscle Quality and Protein Physicochemical Properties during Frozen Storage and Correlation Analysis

In order to explore the changes of Trachurus japonicus freshness quality during frozen storage, the color, conductivity, ice crystal size and morphology, texture, K value, TBA value, Raman spectrum, secondary structure of total protein, total sulfhydryl content, active sulfhydryl content and Ca2+-ATPase activity of myofibrillar protein were investigated during the frozen storage of ?18 ℃ for 90 days with vacuum and air packaging. The results showed that the K value, L* value, whiteness value and TBA value of samples both in VP and AP groups increased gradually with the extend of storage time, among which the K value increased by 65.83% and 66.44% after frozen storage for 90 days, respectively. At the same time, the porosity of ice crystal in fish muscle increased gradually, while a* value, b* value, hardness, chewiness and resilience decreased gradually, however the cohesiveness and conductivity increased firstly and then decreased. The α-helix percentage of muscle protein decreased from 63.28% to 43.70% and 41.91%, respectively, while β-folding, β-turning and random curling percentage increased gradually. The total sulfhydryl content and active sulfhydryl content of myofibrillar protein decreased gradually, Ca2+-ATPase activity decreased by 63.58% and 72.52%, respectively. The packaging had little different effect on muscle quality during frozen storage, but had a certain effect on protein biochemical characteristics in which vacuum packaging effect was slightly better than that of air packaging. Correlation analysis showed that K value, whiteness value, TBA value, sulfhydryl content, Ca2+-ATPase activity, total protein secondary structure content of the samples of the two groups were significantly correlated (P<0.05) or highly significantly correlated (P<0.01) with the frozen storage time and each other, indicating that those indexes could be used as effective indexes to evaluate the quality change of T. japonicus during frozen storage. This study provided a theoretical reference for the further studying of the quality change mechanism and the shelf life prediction of T. japonicus.