Postmorten glycolysis in ground skeletal muscle as influenced by prerigor freezing and subsequent thawing.

Ground bovine longissimus and rabbit white muscles were frozen (-25 degrees C) in the prerigor state and subsequently thawed(+20 degrees C) to determine the combined effect of grinding and freezing on glycolytic metabolites and enzymes. Frozen ground muscle, when compared to unfrozen ground tissue, showed significantly lower hexose monophosphates and significantly greater levels of all metabolites from fructose diphosphate to phosphoenolpyruvate, indicating activation of phosphofructokinase and inhibition of pyruvate kinase during the freezing process. Thawing caused rapid glycolysis and the metabolites returned to near unfrozen levels by the time glycolysis ceased, due to strong activation of phosphorylase by Ca2+. Both muscle types had a similar pattern of changes.