Instrumental meat quality characteristics associated with aged m. longissimus thoracis from the four Canadian beef quality grades

Canadian beef is quality graded to characterize the potential eating quality of the cooked product. Instrumental meat quality characteristics of 48 m. longissimus thoracis (LT, rib eye) from four Canadian beef grades (Canada A, AA, AAA, and Prime, n = 12) before and after an additional 14-d aging were compared using a split plot design with grade, aging, and their interaction as fixed sources of variation. Mean percentage intramuscular fat was greatest in Canada Prime muscle and least in Canada A and AA muscles (P < 0.0001), whereas mean percentage drip loss was lower in Canada Prime muscle than in muscle from all other grades (P = 0.0348). Canada Prime and AAA muscles were redder and yellower than muscles from other grades even after aging (P < 0.03), which may be associated with increased fat content and indicative of accelerated myoglobin oxidation and increased myoglobin oxygenation. Shear force was not different among the Canada grades, although the differences between Canada AA cooked beef LT and that of Canada Prime and AAA carcasses approached significance (P = 0.0993). Results indicated that Canada quality grades did not differentiate beef on cooked product tenderness, substantiating that muscle compositional characteristics alone define beef grade advantages.