Evaluation of effects of heating temperature and time on tenderness of beef based on principal component analysis

Thermal processing of meat is an essential step in meat industry, which turns raw meat into edible meat. Beef with high degree of doneness is the main form of beef consumption in China. In order to solve the problem that the cooking temperature and central temperature of beef with high degree of doneness are not consistent with the shear force method (NY/T 1180-2006), in this study, a comprehensive evaluation method of tenderness of beef with high degree of doneness was proposed based on principal component analysis (PCA), taking 3 parts of Xianan cattle i.e. shoulder, strip loin and topside as examples, representing the meat of front, middle and hindquarters of cattle, respectively. Nine texture indices including cooking loss, shear force, hardness, adhesiveness, springiness, cohesiveness, gumminess, chewiness and resilience were studied by PCA to evaluate the tenderness quality of the shoulder, strip loin, and topside parts of 6 Xianan cattle, treated at different temperatures (70, 80, 90 and 100 ℃) and time (0, 30, 60, 90, 120 and 180 min) by using SAS (statistical analysis system) software. Three principal components were extracted, and the contribution rates of variance were 56.53%, 24.43%, 8.62% respectively, which represented the mastication, compression and shear characteristics of beef, respectively. The cumulative contribution rate of variance was 89.58%, and a comprehensive evaluation model was established. The results showed that the third principal component with shear force as the main load accounted for only a small proportion in the comprehensive evaluation of meat tenderness, which did not represent all the information of meat tenderness in the tenderness evaluation process of beef with high degree of doneness. Therefore, the shear force should not be regarded as the main variable for evaluating the tenderness of beef with high degree of doneness. The indices related to the texture of meat should be comprehensively considered in the evaluation process. The comprehensive score results showed that the heating temperature and time significantly affected the comprehensive score. When the center temperature of meat was less than 80 ℃, with the extension of time, the score of beef tenderness was stable, and when the center temperature was more than 80 ℃, the score decreased. And for the same meat, the higher the center temperature, the longer the duration, the lower the score. The use of PCA can reduce the number of texture indices, and make the evaluation process simplified, and it provides theoretical reference for the tenderness evaluation of beef with high degree of doneness.