Measurement of the heat production in beef muscle during rigor mortis

Summary The post mortem heat production in beef at body temperature has been measured by observing the rise in temperature of the muscles M. semitendinosus and M. extensor carpi radialis when enclosed in an insulated container submerged in a water bath at 37°C. The variation with time of the muscle's radial temperature profile was measured using a multi-junction thermocouple probe and a data logger, and this enabled the heat loss to be calculated. The mean values obtained for the total heat production during rigor mortis were 6·4 kJ/kg for M. semitendinosus and 7·9 kJ/kg for M. extensor carpi radialis, these being equivalent to temperature rises of 1·8°C and 2·2°C respectively, in perfectly insulated muscles. The heat production per unit decrease in pH averaged 5·4 kJ/kg for M. semitendinosus and 6·8 kJ/kg for M. extensor carpi radialis. The rate of heat production reached a mean maximum level of 1·5 kj/kg hr, which was maintained until 4–5 hr post mortem before decreasing to zero. These results are in general conformity with calculations based on the known relations of glycogen, phosphocreatine and ATP.