High glycolytic potential does not predict low ultimate pH in pork.

Extent of postmortem pH decline influences meat quality development. To better understand physiological determination of ultimate pH (pHu), we utilized female and castrated male pigs from a line whose selection index includes differentiated pHu. All genotypes of AMP-activated protein kinase γ3 subunit (AMPKγ3) V199I site were present. The mutant 199II genotype increased pHu, but only in castrated males. Genotype affected glycolytic potential (GP), but GP was weakly associated with pHu. A subset of animals was selected based on low (-Gly) and high (+Gly) residual glycogen content, and compared with AMPKγ3 200Q, which is associated with low pHu. Both +Gly and 200Q muscle contained glycolytic substrate at 24h; however, 200Q muscle generated low pHu and greater lactate compared to +Gly. Additionally,-Gly and +Gly groups exhibited similar pHu despite a large difference in GP. In conclusion, high GP does not appear to directly impact the extent of postmortem pH decline.