EFFECT OF ANTEMORTEM ENVIRONMENTAL TEMPERATURES ON POSTMORTEM GLYCOLYSIS AND TENDERNESS IN EXCISED BROILER BREAST MUSCLE

The effects of heat stress (38°C), cold stress (4°C) and extreme cold stress (−20°C) before slaughter on the tenderness and postmortem glycolysis of the excised chicken breast muscle were studied. Heat stress significantly (p < 0.05) increased the toughness of breast muscle. Though statistically not significant, cold stress also adversely affected the tenderness. The heat-stressed birds showed higher zero hr glycogen, higher zero hr pH and significantly (p < 0.05) lower ultimate pH than the controls. The cold-stressed birds showed intermediate values in these parameters. Highly significant correlations were observed between shear value and each of these three parameters. Glycolysis rate and final moisture content were minor factors which affected the muscle tenderness to a limited extent. The slightly elevated lactatedehydrogenase and creatine phosphokinase activities in serum and breast muscle of stressed birds failed to account for any variations in tenderness.