England Eric M, Matarneh Sulaiman K, Oliver Emily M, Apaoblaza Ariel, Scheffler Tracy L, Shi Hao, Gerrard David E
Department of Animal and Poultry Sciences, Virginia Polytechnic Institute and State University, Blacksburg, VA 24061, United States.
Department of Animal and Poultry Sciences, Virginia Polytechnic Institute and State University, Blacksburg, VA 24061, United States.
Meat Sci. 2016 Apr;114:95-102. doi: 10.1016/j.meatsci.2015.10.010. Epub 2015 Oct 23.
Skeletal muscle glycogen content can impact the extent of postmortem pH decline. Compared to glycolytic muscles, oxidative muscles contain lower glycogen levels antemortem which may contribute to the higher ultimate pH. In an effort to explore further the participation of glycogen in postmortem metabolism, we postulated that increasing the availability of glycogen would drive additional pH decline in oxidative muscles to equivalent pH values similar to the ultimate pH of glycolytic muscles. Glycolysis and pH declines were compared in porcine longissimus lumborum (glycolytic) and masseter (oxidative) muscles using an in vitro system in the presence of excess glycogen. The ultimate pH of the system containing longissimus lumborum reached a value similar to that observed in intact muscle. The pH decline of the system containing masseter samples stopped prematurely resulting in a higher ultimate pH which was similar to that of intact masseter muscle. To investigate further, we titrated powdered longissimus lumborum and masseter samples in the reaction buffer. As the percentage of glycolytic sample increased, the ultimate pH decreased. These data show that oxidative muscle produces meat with a high ultimate pH regardless of glycogen content and suggest that inherent muscle factors associated with glycolytic muscle control the extent of pH decline in pig muscles.
骨骼肌糖原含量会影响宰后pH值下降的程度。与糖酵解型肌肉相比，氧化型肌肉生前的糖原水平较低，这可能是导致其最终pH值较高的原因。为了进一步探究糖原在宰后代谢中的作用，我们推测增加糖原的可利用性会促使氧化型肌肉的pH值进一步下降，达到与糖酵解型肌肉最终pH值相当的水平。我们使用体外系统，在糖原过量的情况下，比较了猪的腰大肌（糖酵解型）和咬肌（氧化型）的糖酵解过程和pH值下降情况。含有腰大肌的系统的最终pH值达到了与完整肌肉中观察到的值相似的水平。含有咬肌样本的系统的pH值下降过早停止，导致最终pH值较高，这与完整咬肌的情况相似。为了进一步研究，我们在反应缓冲液中滴定了腰大肌和咬肌的粉末样本。随着糖酵解型样本百分比的增加，最终pH值降低。这些数据表明，无论糖原含量如何，氧化型肌肉产生的肉最终pH值都较高，这表明与糖酵解型肌肉相关的内在肌肉因素控制着猪肌肉中pH值下降的程度。
