冷藏过程中草鱼肌肉蛋白质特性的变化

将草鱼在4℃条件冷藏0、2、4、6、8、10 d后,提取并制备其肌肉蛋白质样品,以体积排阻色谱、流变仪、差示扫描量热法等方法分析其蛋白质分子量分布、持水性能、溶液黏度、热力学性质及肌动球蛋白盐溶性的变化。结果显示,随着冷藏时间的延长,草鱼肌肉蛋白质分子量总体变小,持水力、溶液黏度、肌动球蛋白溶出量均呈下降趋势,热变性焓先降低后升高;其中持水力冷藏前期下降剧烈,第8 d降幅达56.12%;黏度在低剪切速率下下降明显,在剪切速率20 s^-1条件下黏度由第0 d的0.89 Pa·s降至第10 d的0.05 Pa·s;肌动球蛋白的溶出量在冷藏前6 d下降趋势明显,冷藏第6 d时降幅达40.96%;冷藏后的蛋白质样品的DSC曲线出现两个吸热峰,其最大峰的起始温度和峰顶温度均在第6 d时最大,而热变性焓在第6 d时最低,表明冷藏第6 d是草鱼肌肉蛋白质变化的关键时间点。研究结果为了解冷藏过程中草鱼肌肉品质劣变机制提供了基础数据。

Changes in Characteristics of Muscle Protein from Grass Carp during Cold Storage Period

To explore the changes in physicochemical characteristics of muscle protein of grass carp during cold storage, the muscle protein samples were prepared from the grass carp fillets which were refrigerated at 4 ℃ for 0, 2, 4, 6, 8 and 10 d, respectively. And their molecular weight (MW) distribution, water holding capacity（WHC）, solution viscosity, thermodynamic property, as well as salt solubility of actomyosin were determined by size exclusion HPLC, rheometer and differential scanning calorimetry (DSC), etc. The results showed that the average MW of muscle protein was decreased during the whole cold storage period, while the WHC decreased severely in the early stage of cold storage and was dropped by 56.12% at the 8th day. The apparent viscosity of muscle protein decreased quickly at low shear rates, and fell from 0.89 Pa·s of 0 d to 0.05 Pa·s of 10 d at a shear rate of 20 s?1. The salt solubility of actomyosin declined obviously and dropped by 40.96% after 6 d of cold storage. Moreover, two endothermic peaks were observed in DSC curves of the protein samples from refrigerated fish muscles, and the onset temperature (T_e) and peak temperature (T_m) of the biggest peak were both maximized at the 6th day, while its corresponding enthalpy change (?H) was minimized. The results indicated that the 6th day of cold storage was a key time point for complex changes of grass carp muscle proteins. This study provides basic data for better understanding the deterioration mechanism of grass carp muscle during cold storage.