Tenderness classification of beef: IV. Effect of USDA quality grade on the palatability of "tender" beef longissimus when cooked well done

The objective of this experiment was to determine the impact of USDA quality grade on the palatability of "tender" longissimus when cooked well done; Warner-Bratzler shear force was determined on longissimus thoracis steaks aged 3 or 14 d postmortem (cooked to 70 degrees C) fi om carcasses of 692 steers and heifers. Steaks from 31 carcasses with Modest or Moderate marbling scores (Top Choice) and steaks from 31 carcasses with Slight(00) to Slight(40) marbling scores (Low Select) were selected for this experiment from carcasses identified as "tender" (shear force < 5.0 kg at 3 d postmortem). Longissimus thoracis steaks with 3 or 14 d of postmortem aging were cooked to 80 degrees C and evaluated by a trained sensory descriptive attribute panel. Top Choice steaks had higher (P < .05) juiciness (5.8 vs 5.3) and beef flavor intensity ratings (4.9 vs 4.6) than Low Select steaks. Aging of steaks for 14, rather than 3, d postmortem improved (P < .05) beef flavor intensity rating (4.8 vs 4.7) but not (P > .05) juiciness rating (5.6 vs 5.5). The interaction (P < .05)of quality grade and aging time for tenderness rating indicated that Top Choice steaks were more tender (P < .05) with 3 d of aging than steaks from Low Select carcasses (6.3 vs 5.8), but steaks from Top Choice and Low Select carcasses had similar(P > .05) tenderness ratings after 14 d of aging (7.0 and 6.8),Compared to palatability of steaks from Low Select carcasses, the palatability of steaks fi om Top Choice carcasses was less affected by elevated degree of doneness in "tender" longissimus thoracis, especially when steaks were aged for only 3 d. Although differences in sensory traits between Top Choice and Low Select steaks were small, the consumers who cook beef well done may benefit from implementation of tenderness classification in conjunction with USDA quality grade.