The cooking of single myofibres, small myofibre bundles and muscle strips from beef M. psoas and M. sternomandibularis muscles at varying heating rates and temperatures.

When single myofibres are heated in an aqueous medium up to temperatures of 90°C at pH 5·5, they do n ot shorten but instead decrease in diameter. This decrease begins slowly at 40° and reaches a maximal rate and extent at 60°, when the myofibre volume has decreased to 50% of the initial volume and about 60% of the cell water has been expelled. The myofibres behave similarly when the pH of the medium is raised to 6·8, but the loss of cell water is considerably less (about 42%). When small myofibre bundles are heated from 10° to 60° they behave similarly to single myofibres by decreasing, in diameter only, from 40° to about 63°. At the latter temperature their volume has decreased to 60% of the initial value and about 48% of the bundle water has been expelled. Above 64° the bundles shorten, the shortening reaching about 30% of the initial length at 90°. This shortening, combined with the diameter decrease, leads to a volume decrease to 43% of the initial value and to a loss of about 68% of the cell water.