Department of Animal and Food Sciences, Oklahoma State University, Stillwater, Oklahoma 74078, United States.
Department of Biochemistry and Molecular Biology, Oklahoma State University, Stillwater, Oklahoma 74078, United States.
J Agric Food Chem. 2024 Nov 13;72(45):25275-25285. doi: 10.1021/acs.jafc.4c06490. Epub 2024 Nov 4.
Dysregulated muscle glycogen metabolism preslaughter contributes to aberrant postmortem muscle pH (>5.8) in dark-cutting beef phenotypes. However, the underlying mechanisms have remained elusive. Herein, we examine the glycogen dependent regulation of postmortem muscle pH decline and darkening in beef. We show that supplementation of glycogen in vitro restores postmortem pH decline in dark-cutting beef by reverting the metabolome toward a typical postmortem muscle state characterized by increased activities of enzymes glycogen phosphorylase and lactate dehydrogenase ( < 0.05) coupled with a pronounced abundance of glycolytic metabolites and reduced abundance of tricarboxylic acid cycle and amino acid metabolites. Furthermore, concurrent inhibition of mitochondrial respiration at complexes I, IV, and V with glycogen supplementation stimulates greater pH decline. Together, our findings show that supplementing glycogen at low concentrations (10 mM) can reprogram the dark-cutting beef muscle's metabolome toward typical postmortem state and promote muscle acidification. Thus, enhancing glycogen levels could represent a promising strategy for mitigating dark-cutting beef phenotypes and improving meat quality.
宰前肌肉糖原代谢失调导致暗切割牛肉表现型异常的死后肌肉 pH 值（>5.8）。然而，其潜在机制仍难以捉摸。在此，我们研究了糖原对牛肉死后肌肉 pH 值下降和变暗的依赖调节。我们表明，体外补充糖原可通过将代谢组恢复到典型的死后肌肉状态来恢复暗切割牛肉的死后 pH 值下降，其特征是糖原磷酸化酶和乳酸脱氢酶（<0.05）的活性增加，同时伴有糖酵解代谢物的明显增加和三羧酸循环和氨基酸代谢物的减少。此外，在补充糖原的同时抑制线粒体呼吸复合物 I、IV 和 V 会刺激更大的 pH 值下降。总之，我们的研究结果表明，低浓度（10 mM）补充糖原可以将暗切割牛肉肌肉的代谢组重新编程为典型的死后状态，并促进肌肉酸化。因此，提高糖原水平可能是缓解暗切割牛肉表型和改善肉质的一种有前途的策略。
