Effect of age and cut on consistency of tenderness and leanness of beef

Longissimus dorsi and Semitendinosus muscles from 180 crossbred steers, representing three age groups and grading Canada A, were evaluated for consistency in leanness and tenderness. The majority of the carcasses graded Canada Al and received Canada A or AA marbling scores. Post-mortem pH and sarcomere lengths were normal. Percent fat in the muscle samples was not affected by age and few samples exceeded 10% fat. Twelve month L. dorsi samples were found to be significantly more tender and less chewy than the 24 month samples, as were the 12 month Semitendinosus samples compared to either the 17 or 24 month samples. Meat from 12 month animals was consistently tender but the 17 or 24 month samples were not. Chewiness, assessed as 'force X time to chew: identified more animals as tough than did tenderness, assessed as 'force to chew', early in the mastication process. Assessment during the later stages of mastication appeared to be more important In assessing tenderness of Semitendinosus muscle than L. dorsi.