温度波动对大目金枪鱼低温流通期间品质变化的影响

Effect of Temperature Fluctuation on the Quality of Big-Eye Tuna(Thunnus obesus)during Low Temperature Circulation

为研究温度波动对大目金枪鱼低温流通期间品质变化的影响,本实验分别模拟了冷链(CK组)与2种断链(超市直销模式L1组、超市零售模式L2组)流通过程,并通过质构分析、pH值、高铁肌红蛋白质量分数、总挥发性盐基氮含量、组胺含量、菌落总数与感官分析等指标,综合表征不同低温流通过程对大目金枪鱼品质变化的影响。结果表明:各组样品在流通过程中的pH值、高铁肌红蛋白质量分数、总挥发性盐基氮含量、组胺含量与菌落总数均呈上升趋势;相较于CK组与L1组,L2组样品流通期间的温度波动最大,其硬度与咀嚼性增长最显著,品质劣变最明显;L2组样品在216 h时,pH值为6.66,高铁肌红蛋白质量分数升至35.23%,鱼肉褐变严重;此时,大目金枪鱼的总挥发性盐基氮含量为19.14 mg/100 g,组胺含量为89.97 mg/kg,菌落总数为5.43(lg(CFU/g)),感官评分为-2;由指标间的相关性分析可知,各组鱼肉样品间的高铁肌红蛋白质量分数、总挥发性盐基氮含量、组胺含量、菌落总数互相间呈显著正相关(P<0.01、P<0.05),这些指标可用于评价大目金枪鱼在不同低温流通过程中的品质变化。同时,流通期间应尽量减少温度波动,尤其是剧烈温度波动,其对大目金枪鱼的品质易造成明显影响。

In order to analyze the effect of temperature fluctuation on the quality of big-eye tuna(Thunnus obesus) during low-temperature circulation, changes in texture properties, pH, metmyoglobin(MetMb) content, total volatile basic nitrogen(TVB-N) content, histamine content, total viable count(TVC) and sensory evaluation score were measured during simulated cold chain logistics with constant(control) and fluctuating temperatures(L1: supermarket direct marketing;L2: supermarket retailing). The results showed that pH, MetMb content, TVB-N content, histamine content and TVC rose during the experimental period for all groups. The temperature fluctuation in group L2 was the most obvious compared with the other groups, and group L2 showed the most significant increase in hardness and chewiness as well as the most obvious quality deterioration. After 216 h, the pH of group L2 was as high as 6.66 and the MetMb content was increased up to 35.23%, indicating severe browning. In addition, the TVB-N content was 19.14 mg/100 g, histamine content 89.97 mg/kg, TVC 5.43(lg(CFU/g)), and sensory score-2 points. Correlation analysis demonstrated that the MetMb content, TVB-N content, histamine content and TVC were positively correlated with each other for all groups(P < 0.01 or P < 0.05), which could therefore be used to evaluate the quality changes of big-eye tuna during low temperature circulation. Conclusively, temperature fluctuations should be reduced as much as possible during circulation. Particularly, severe temperature fluctuations could affect the quality of big-eye tuna greatly.