Effect of temperature on porcine-muscle metabolism studied in isolated muscle-fibre strips

Abstract

In the period before and after slaughter, muscle temperature differs between pigs, which is likely to influence muscle metabolism. Muscle-fibre strips were isolated under anaesthesia from six halothane-negative Large White pigs and eight halothane-positive Pietrain pigs and kept in oxygenated Krebs medium at 38, 40, or 42°C, to study the effects of temperature on muscle metabolism. During a period of oxygenation, contraction measurements were carried out to assess the physiological state of the muscle-fibre strips. Aerated Krebs solution was replaced by paraffin oil at the same temperature to simulate post-mortem muscle metabolism. Pietrain muscle-fibre strips were more affected by preparation methods than Large White muscle strips, which led to a higher metabolite breakdown at the time of cessation of the oxygen supply. Pietrain muscle-fibre strips also showed a larger decrease in twitch-force contraction during the period of oxygenation. A moderate effect of temperature on energy metabolism could be seen in muscle-fibre strips of both types of pig, with increasing post-mortem metabolite breakdown at higher temperatures. However, this effect can play only a limited role in the tremendous acceleration of the post-mortem pH fall as observed in PSE muscle (up to five to ten times the normal rate).