Differences in the post‐mortem kinetics of the calpain system in meat from bulls and steers

摘要

Abstract Strip loins (longissimus thoracis et lumborum) from bulls with normal ultimate pH (NOR, pHu < 5.7), bulls with unacceptably high pH (HI, pHu > 5.7), and steers were compared after storage at 15°C. HI samples had higher shear forces 120 hours post‐slaughter than NOR and steer samples (P < 0.05). Calpastatin and μ‐calpain activities were higher in the NOR bulls than in steers, but the rates of decline in these activities were more rapid in NOR samples. The activity of μ‐calpain was low at all times and appeared to be involved in the increased toughness of the HI samples. The activity of m‐calpain and the calpastatin : μ‐calpain activity ratio provided a good prediction of shear force 120 hours post‐slaughter in the strip loin (R2 = 0.70; P < 0.001). This suggests that calpastatin, μ‐calpain, and m‐calpain all play a role in tenderisation and that on‐farm and pre‐slaughter management rather than post‐slaughter treatment need to be used to decrease the incidence of high pH meat.