Proteolytic changes of myofibrillar and small heat shock proteins in different bovine muscles during aging: Their relevance to tenderness and water-holding capacity.

The objective of this study was to determine the proteolytic changes of myofibrillar and small heat shock proteins (HSPs) in different muscles during aging and to evaluate their relevance to meat quality attributes. From 8 beef carcasses, longissimus lumborum (LL), semimembranosus (SM), and psoas major (PM) muscles were obtained, cut into sections and assigned to various aging periods up to 23d. PM exhibited limited aging potential in quality developments shown by lower extents of shear force, water-holding capacity (WHC), and proteolytic changes, including calpain 1 autolysis, troponin T, and HSP27 compared to LL and SM. Conversely, LL had an increase in tenderization and WHC, which was accompanied with more extended calpain 1 autolysis, proteolysis and HSP27 degradation, compared with other muscles. The results of this study suggest that postmortem proteolytic changes of myofibrillar proteins, small HSPs and apoptotic factors occur in a muscle-specific manner, which is likely attributed to different rate and extent of meat quality developments of each muscle during aging.