Tenderness classification of beef: III. Effect of the interaction between end point temperature and tenderness on Warner-Bratzler shear force of beeflongissimus

The objectives of this experiment were to determine 1) whether end point te mperature interacts with tenderness to affect Warner-Bratzler sheer force o f beef longissimus and 2) if so, what impact that interaction would have on tenderness classification. Warner-Bratzler shear force was determined on l ongissimus thoracis cooked to either 60, 70, or 80 degrees C after 3 and 14 d of aging fi om carcasses of 100 steers and heifers. Warner-Bratzler shea r force values (3- and 14-d aged steaks pooled) for steaks cooked to 70 deg rees C were used to create five tenderness classes. The interaction of tend erness class and end point temperature was significant (P < .05). The incre ase in Warner-Bratzler shear force as end point temperature increased was g reater (P < .05) for less-tender longissimus than more-tender longissimus ( Tenderness Class 5 = 5.1, 7.2, and 8.5 kg and Tenderness Class 1 = 2.4, 3.1 , and 3.7 kg, respectively, for 60, 70, and 80 degrees C). The slopes of th e regressions of Warner-Bratzler shear force of longissimus cooked to 60 or 80 degrees C against Warner-Brattier shear force of longissimus cooked to 70 degrees C were different (P < .05), providing additional evidence for th is interaction, Correlations of Warner-Bratlzer shear force of longissimus cooked to 60 or 80 degrees C with Warner-Brattier shear force of longissimu s cooked to 70 degrees C were .90 and .86, respectively. One effect of the interaction of tenderness with end point temperature on tenderness classifi cation was to increase (P < .01) the advantage in shear force of a "Tender" class of beef over "Commodity" beef as end point temperature increased (.2 4 vs .42 vs .60 kg at 14 d for 60, 70, and 80 degrees C, respectively). Whe n aged 14 d and cooked to 80 degrees C, "Commodity" steaks were six times m ore likely (P < .01) than "Tender" steaks to have shear force values 2 5 kg (24 vs 4%). The end point temperature used to conduct tenderness classific ation did not affect classification accuracy, as long as the criterion for "Tender" was adjusted accordingly. However, cooking steaks to a greater end point temperature than was used for classification may reduce classificati on accuracy. The beef industry could alleviate the detrimental effects on p alatability of consumers cooking beef to elevated degrees of doneness by id entifying and marketing "Tender" longissimus.