牛肉低温储藏期间质构参数分析及新鲜度指标的确定

为了寻求低温储藏期间牛肉新鲜度的快速检测指标,将牛肉置于5℃冷鲜密封储藏和-5℃冷冻密封储藏2种条件下,用挥发性盐基氮检测(total volatile basic nitrogen,TVB-N)、恒温干燥法与质构多面分析方法(texture profile analysis,TPA)对牛肉样品(储藏时间0、3、6、9、12、15 d)进行检测。发现-5℃冷冻条件下储藏的牛肉比5℃冷藏条件下储藏的牛肉保鲜时间更长,且随着储藏时间的增加2种储藏条件下牛肉的含水率都降低。得到0~15 d内5℃冷鲜密封储藏和-5℃冷冻密封储藏牛肉质地参数(硬度1、硬度2、回复性)的变化规律。用二因素方差分析得知储藏时间、储藏温度对回复性均有显著影响(P0.05),用相关性分析得知硬度1、硬度2、回复性与新鲜度指标显著相关(P0.05)。选取2℃条件下冷鲜密封储藏牛肉进行试验验证,测定挥发性盐基氮与回复性,对试验数据进行统计分析并线性拟合,挥发性盐基氮与回复性两者的线性函数关系具有较好拟合优度(R2=0.85311),挥发性盐基氮值与回复性呈显著相关(P0.05)。因此回复性可作为牛肉低温储藏期间新鲜度的检测指标。研究结果可为生产储运过程与日常生活中牛肉保鲜和保持质地口感提供依据。

Analysis of texture parameters and determination of freshness index of beef in low temperature storage

Beef would be oxidative decomposition and decayed because of enzyme, external environment, microorganisms, and many other factors during the storage. Beef freshness detection is urgently needed. Sensory evaluation method is easily affected by the reviewers and environment. Chemical evaluation is destructive and tedious. Therefore, it is necessary to seek a rapid detection method to monitor the freshness of the beef in the storage and transportation. Beef samples are placed in the 5℃ cold sealed and the -5℃ frozen sealed conditions respectively. Beef samples are detected by using the method of total volatile basic nitrogen(TVB-N), constant temperature drying and texture profile analysis (TPA) in the two storage conditions during different storage days(0, 3, 6, 9, 12, 15 d). The freshness keeps longer in the -5℃ frozen sealed condition than that in the 5℃ cold sealed condition. The water content decreased in the two conditions, water content decreased in the -5℃ frozen sealed condition is more than that in the 5℃ cold sealed condition. The laws of texture parameters (hardness, resilience) during the storage days are analyzed. With increase of storage days in two conditions, hardness 1 and hardness 2 shows decreasing trends. In the condition of 15 days storage, the value of hardness 1 and hardness 2 are closed. The value of hardness 1 and hardness 2 that beef stored in 5℃ cold sealed condition are higher than that beef stored in -5℃ frozen sealed condition during 0-15 days. With increasing of storage days, resilience is decreased. Beef is stored in 5℃ cold sealed condition has a better resilience than that in -5℃ frozen sealed condition in 0-15 days. The test result of adhesiveness is stochastic and can't accurately reflect the chewing, the meat fibers on the tongue, teeth, jaw and other contact surface adhesion properties of beef. The method of two-way ANOVA is used to analyze the influence to the texture parameters. The results present that resilience are significantly influenced by the storage time and storage temperature (P<0.05). Correlation analysis of texture parameters and freshness in the 2 storage conditions are done. In 5℃ cold sealed condition, the correlation coefficient between hardness1, hardness 2, resilience, adhesiveness and freshness are -0.89791, -0.92072, -0.88443, -0.34857; in -5℃ frozen sealed condition, the correlation coefficient between hardness1, hardness 2, resilience, adhesiveness and freshness are -0.88818, -0.8976, -0.98148, 0.38746. Correlation of hardness1, hardness 2, resilience and freshness are significant at the 0.05 level in the two conditions. Detect TVB-N value and resilience of the beef in the of 2℃cold fresh seal storage condition, TVB-N value and resilience can fit linearly (R2=0.85311). TVB-N value and resilience was significantly correlational (P<0.05). Resilience can be used as detection indicator for beef freshness in storage. This study provides a method for rapid detection of beef freshness, and provides the basis for beef fresh keeping during production and transportation.