title: Excess glycogen does not resolve high ultimate pH of oxidative muscle.
abstract: 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.
authors.affiliation: Department of Animal and Poultry Sciences, Virginia Polytechnic Institute and State University, Blacksburg, VA 24061, United States.
authors.forename: Eric M
authors.initials: EM
authors.lastname: England
authors.affiliation: Department of Animal and Poultry Sciences, Virginia Polytechnic Institute and State University, Blacksburg, VA 24061, United States.
authors.forename: Sulaiman K
authors.initials: SK
authors.lastname: Matarneh
authors.affiliation: Department of Animal and Poultry Sciences, Virginia Polytechnic Institute and State University, Blacksburg, VA 24061, United States.
authors.forename: Emily M
authors.initials: EM
authors.lastname: Oliver
authors.affiliation: Department of Animal and Poultry Sciences, Virginia Polytechnic Institute and State University, Blacksburg, VA 24061, United States.
authors.forename: Ariel
authors.initials: A
authors.lastname: Apaoblaza
authors.affiliation: Department of Animal and Poultry Sciences, Virginia Polytechnic Institute and State University, Blacksburg, VA 24061, United States.
authors.forename: Tracy L
authors.initials: TL
authors.lastname: Scheffler
authors.affiliation: Department of Animal and Poultry Sciences, Virginia Polytechnic Institute and State University, Blacksburg, VA 24061, United States.
authors.forename: Hao
authors.initials: H
authors.lastname: Shi
authors.affiliation: Department of Animal and Poultry Sciences, Virginia Polytechnic Institute and State University, Blacksburg, VA 24061, United States. Electronic address: dgerrard@vt.edu.
authors.forename: David E
authors.initials: DE
authors.lastname: Gerrard
mesh_terms: D000818:Animals; D006003:Glycogen / Q000378:metabolism*; D006019:Glycolysis; D006801:Humans; D006863:Hydrogen-Ion Concentration; D008460:Meat / Q000032:analysis*; D018482:Muscle, Skeletal / Q000378:metabolism*; D010084:Oxidation-Reduction; D011180:Postmortem Changes; D013552:Swine
chemical_list: D006003:Glycogen
keywords: Glycogen; Glycolytic capacity; Meat quality; Pork; Ultimate pH