Regulation of post-mortem glycolysis in ruminant muscle

Abstract

Abstract. As a tissue, muscle has the unique ability to switch its metabolic source of ATP, the energy currency underpinning muscle function. During oxygen debt, such as that occurring immediately following the death of animals, anaerobic metabolism is initiated in an attempt to restore homeostasis within the muscle. The cascade of biochemical events that are initiated is paramount in the context of meat quality. This review revisits this reasonably well-known subject but takes a new perspective by drawing on the understanding outside the traditional discipline of meat science. Our understanding of the intrinsic regulators of glycolytic flux has improved but knowledge gaps remain. Further efforts to understand how the glycolytic enzyme kinetics are influenced by both pre-and post-slaughter factors will be beneficial in the ongoing quest to maximise fresh meat quality.

Characteristics of selected pork muscles 45 min and 24 h post mortem

“…Warner et al (1993) The accumulation of lactate is a good measure of the extent and level of glycolysis. It is, however, deceptive to use the level of lactate directly to determine the fall in the pH value in the muscles (Ferguson and Gerrard 2014). A significant correlation (r = -0.61, P < 0.001) was found between pH values and the level of lactic acid 45 min post mortem, though not 24 h after slaughter (r = -0.25, P > 0.05).…”

Muscle metabolism in sheep and cattle in relation to high rigor temperature – overview and perspective

“…Fasting will deplete glycogen, but mixing of bulls before slaughter will increase glycogenolytic rate and hence be more likely to cause high rigor temperatures (Tarrant 1989). Emotional stress preslaughter resulting in an adrenal response, even naturally experienced, together with moderate activity, causes elevation of cAMP, one of the main drivers of glycolysis (Ferguson and Gerrard 2014). Obviously high fat levels and muscle mass (large carcasses) will then further exacerbate the effect on rate of glycogenolyses.…”

“…Therefore, DFD (dark, firm, dry) meat caused by low preslaughter glycogen levels may more likely be a problem in stressed animals than high rigor temperatures, although the study did not report on the latter. However, Ferguson and Gerrard (2014) pointed out that type and duration of stressors will determine whether glycogen levels and, more important to this discussion, glycolytic rate will be affected. Fasting will deplete glycogen, but mixing of bulls before slaughter will increase glycogenolytic rate and hence be more likely to cause high rigor temperatures (Tarrant 1989).…”

“…However, Simmons et al (2006) suggested that this might be a complicated procedure, because not all carcasses have the same specifications with regard to their reaction to electrical impulses. It should also be noted that ES advances pH decline (glycolysis) not only during the application but also after the application has ceased, as illustrated in Ferguson and Gerrard (2014), and that the effect of stimulation depends on the type and duration of the application. Intrinsic factors such as muscle type and glycogen level preslaughter may also affect pH decline rate.…”

“…In the review by Ferguson and Gerrard (2014) the authors emphasise that post-mortem energy metabolism plays an important role when muscle changes to meat and that this crucially impacts on the quality of the final product. They also rightfully acknowledge that although models of anaerobic metabolism in living muscle are used to understand transitions in this type of metabolism post mortem, there are gaps in our knowledge, more so for ruminants than for pigs.…”