Abstract

Effects of preslaughter stress and postslaughter ageing regimes on calpain activities and indicators of meat quality were investigated in lambs selected for Fast and Slow glucose clearance (GC). Loins were aged at 11- 17 C for 4, 22 or 70 hrs and then stored frozen (-20 C) or chilled (0 C). Loins aged up to 70 hrs from Fast GC lambs that were exposed to a high level of preslaughter stress had the highest pH and lowest residual glycogen (P<0.05). Calpain activity and cooked meat shear force declined rapidly over the periods of ageing, with significant differences being found between 4 and 22, 22 and 70 hrs aged loins (P<0.05). At the same time pH increased, with a significant difference observed between 4 and 70 hrs aged loins (P<0.05). This data suggests that there is a potential conflict between the beneficial effects of ageing on tenderness and the adverse effects of ageing on the elevation of pH. Calpain I and II activities declined at different times after slaughter in loins aged 22 hrs and then stored chilled for 8 weeks. The loss in calpain I activity was closely associated with a large reduction in shear force over the first 22 hrs after slaughter. The results suggest that an understanding of the factors that control calpain activities may identify methods of improving meat tenderness.

FI, Hill, T Ryan, and AF Death

Proceedings of the New Zealand Society of Animal Production, Volume 53, , 343-346, 1993