Two hundred broilers were commercially processed with and without electrical stunning to determine the effect of stunning on biochemical changes and its relationship to final meat tenderness. Electrically stunned birds were more tender with 30% lower shear values than no-stun controls after 24 hr aging. Breast muscles of electrically stunned birds showed significantly higher ATP, CP and pH, and lower lactate level than no-stun controls during the early processing steps. It was concluded that electrical stunning inhibited the rapid breakdown of ATP, CP and glycogen, and thus delayed the onset of rigor until after spin-chill by which time muscle temperature reached 4°C. Consequently, the rigor process occurred at low temperature where potential heat shortening was avoided, resulting in improved meat tenderness.

The sodium dodecylsulfate‐acrylamide gel electrophoresis was evaluated as a method to determine the cooking temperature to which beef has been cooked. Water soluble protein extracts from bovine muscles cooked to the final temperatures of 65, 70, 75, 80, 85 and 90°C were applied on SDS‐acrylamide gels. The extracts showed characteristic electrophoretic patterns for each cooking temperature examined. The thermoprofiles were highly reproducible among a number of experimental variables. The high degree of accuracy and reproducibility of the method described herein makes it possible to determine the precise temperature to which beef has been cooked, within ± 5°C.

The effects of heat stress (38"C), cold stress (4OC) 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.

The stacking sodium dodecylsulfateacrylamide gel electrophoresis method was evaluated for the qualitative detection of various vegetable proteins in meat products An additional study was also conducted to determine the influence of milk powder, casein, whey protein and egg white proteins on the previously reported electrophoretic procedure for the quantitation of meat and soybean protein content. Soybean, cottonseed flour, cottonseed protein concentrate and peanut protein concentrate exhibited their own unique electrophoretic patterns and were clearly identified when they are added to meat proteins singularly or in various combinations. It was also shown that meat and soybean protein can be successfully identified and quantitated in the presence of milk powder, casein, whey and egg white by employing the described electrophoretic method.

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