Effect of Post‐Mortem Aging and Enzyme Tenderizers on Mucroprotein of Bovine Skeletal Muscle

Abstract

SUMMARY— The effect of post‐mortem aging on the mucoprotein of bovine skeletal muscle was studied, and compared with the effect of papain. The effects were strikingly similar. After either treatment, the isolated mucoprotein products were observed to have lowered viscosity, various degrees of ultra‐filterability, and changes in the character of precipitates formed in the presence of alcohol or phosphotungstic acid. There was a decrease in glucosamine‐galactosamine ratio, which was indicative of lessened glucosamine content. Following post‐mortem aging, a portion of mucoprotein became extractable by KCI. This product was unfilterable, and exhibited low viscosity, with increased hexosamine content and marked loss of nitrogen. Loss of nitrogen was also observed in the ultrafilterable product which resulted after papain treatment. The mucoprotein solubilized by hot water increased in post‐mortem aging. These observations indicated that depolymerization of mucoprotein occurs as a result of either post‐mortem aging or enzyme tenderizer treatment. There appears to be a breakdown of the mucoprotein which produces fragments of lower molecular weight. Lessened nitrogen content, together with the decrease in glucosamine‐galactosamine ratio observed in the KCI‐extractable product isolated after aging as well as in the ultrafilterable product which resulted after papain treatment, indicate a splitting off of protein. Mucoprotein breakdown may be a factor in the increased tenderness as the result of either post‐mortem aging or treatment with papain‐containing tenderizers. Studies are needed which correlate mucoprotein changes with tenderness in order to establish this relationship. It is conceivable that the changes in the mucoprotein fraction observed in this study contribute significantly to the loss of integrity observed in bovine skeletal muscle after post‐mortem aging.