Modelling of the formation of pale, soft and exudative meat: Effects of chilling regime and rate and extent of glycolysis.

The high drip losses and softness of pale, soft and exudative meat are caused by denaturation of myosin before rigor. A simple predictive model is described based on calculations of the time-course of myosin denaturation in carcasses using the known dependence of the rate of denaturation of isolated myosin on temperature and pH (Penny, 1967a). The fraction of myosin denatured increases with the rate of pH fall, then reaches a maximum at a rate of pH fall that depends on the chilling conditions, and finally decreases. The relationship between drip loss and pH(45) value (Warris & Brown, 1987) is well explained by the calculations. The fraction denatured also increases as the final pH decreases, particularly at higher rates of pH fall. Increasing the chilling rate causes a marked reduction in the fraction denatured at low rates of pH fall but is only slightly effective if the rate of glycolysis is very high.