EFFECT OF ULTIMATE pH UPON THE WATER‐HOLDING CAPACITY AND TENDERNESS OF MUTTON

Abstract

SUMMARY— Ultimate pH values in the musculature of sheep ranging from 5.6–7.0 have been obtained by using pre‐slaughter injections of epinephrine. A high speed centrifugal method was used to measure the water‐holding capacity of raw M. semitendinosus (ST), semimembranosus (SM) and biceps femoris (BF). Results showed a high correlation with ultimate pH. Cooking losses end the amounts of centrifugally expressed juice were determined for the SM and BF cooked for 1 hr at either 65°C or 90°C. Cooking losses at 65°C decreased linearly with increasing pH while the losses at 90°C showed little change up to o raw meat pH of ca. 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 organoleptic juiciness, increased linearly with pH. Tenderness of the cooked SM and BF muscles was measured using o Warner‐Bratzler shearing device and an Instron Universal Testing Machine: both gave high objective‐subjective correlations. Instron 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 as ultimate pH increased from 5.6–6.9. Results obtained using the Warner‐Bratzler device showed linear regressions with a significant quadratic component for one muscle at both 65°C and 90°C.