Ultimate pH values in the musculature of sheep ranging from 5.6-7.0 have been obtained by using pre-slaughter injectfens of epinephrine. A high speed centrifugal method was used to measure the water-hdding capacity of raw M. semitendinosus (ST), semimembranosus (SM) and biceps femoris (BF). Results showed a high corrdation with ultimate pH. Cooking losses end the amounts of centrifugally expressed juice were determined for the JM and BF cooked for 1 hr at either 65°C or 90°C. Cooking losses et 65°C decreased linearly with increasing pH while the losses at 90°C showed little change up to o raw meat pH of CQ. 5.9, then decreased linearly with increasing pH. The amount of juice centrifugally expressed from the cooked meat, which has a high positive correlations with orgondeptic juiciness, increased linearly with pff. Tenderness of the cooked SM and BF muscles was measured using o Warner-Bratzler shearing device and cm lnstron Universal Testing Machine: both gave high objective-subjective correlations. lnstron measurements have high negative linear correlations with ultimate pH for both the 65°C and 90°C cooked samples. Hardness of these muscles, cooked at 65°C or 90°C. decreased approximately three-fold 0s ultimate pH increased from 5.649.Results obtained using the Warner-Bratzler device showed linear regressions with a significant quadratic component for one muscle at both 65°C and 90~.

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Pressures of the order of 100 MNm'* applied for 2.5 min or longer to postrigor muscle heated to 40-60"~ improved the tenderness of the meat when subsequently cooked. The magnitude of the effect depended on the intensity and duration of pressurization, and the temperature attained by the meat during pressurization. As judged by taste panel assessment and by shear values of the cooked meat, the properties of pressure-heat treated postrigor muscle approximated those of prerigor pressurized muscle. The process is effective in overcoming toughness associated with contracted muscle. It is suggested that the treatment operates on the myofibrillar component of toughness.

Contributions to the structural strength of meat samples by the myofibrillar and connective tissue components were altered by varying the myofibrillar contraction state, muscle type and the cooking temperature. Shear, tensile and adhesion measurements were used to evaluate quantitatively changes in the properties of the samples. Detailed examination of shear and tensile force‐deformation curves suggested that the initial effect of shear, compression or tensile force was to produce a yield in the myofibrillar structure. After the initial yield, the applied force was probably resisted mainly by the connective tissue structure. Adhesion and tensile values showed changes which indicated a probable rearrangement of the collagen fibers in the connective tissue network as it adjusted to accommodate changes in the myofibrillar contraction state.

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