Abnormally Low Ultimate pH in Pig Muscle

Abstract

THE pH attained when the process of post-mortem glycolysis has ceased—the ultimate pH¹—is influenced by the type of muscle considered, the species in which it occurs and the physiological condition of the animal from which it is derived. In the longissimus dorsi (1. dorsi) muscles of horses², oxen³ and pigs⁴, the glycogen reserves of which have not been depleted by such stresses as pre-slaughter exercise, starvation or excitement, an ultimate pH. of about 5.5 is characteristic. At this pH. the enzymes which effect glycolysis are assumed to be inactivated, and residual glycogen may be found. Stress, by depleting glycogen reserves at or before death, is therefore normally associated with values of ultimate pH above 5.5.