Tenderness and oxidative stability of post-mortem muscles from mature cows of various ages

Two experiments were conducted to investigate the influence of age of mature cows (2–4 yr, 6–8 yr, and 10–12 yr cows; n = 6 in each) on beef quality. In Experiment 1, Longissimus dorsi (LD) steaks were stored at 3 °C for 0–10 d. Steaks from more mature cows had an increased (P < 0.05) Warner-Bratzler shear force (WBSF) and a slower troponin-T post-mortem degradation. Storage reduced WBSF in all steak samples regardless of animal age. In Experiment 2, Semitendinosus (ST) and Semimembranosus (SM) patties were stored at 3 °C for 0–7 d simulating retail display. The rate of lipid oxidation during storage increased with animal age (P < 0.05) and was greater in ST than in SM patties. However, myoglobin oxidation was minimally affected by animal age. Thus, advanced maturation not only intensified cow meat toughness but also lowered its oxidative stability.