| Tenderness is a key palatability trait influencing consumers' perception of meat quality and is influenced by a multitude of factors, including postmortem proteolysis. A fundamental understanding of this biological mechanism regulating tenderness is necessary to decrease variability and increase consumer satisfaction. However, reports regarding the enzyme systems involved in postmortem tenderization are conflicting. Therefore, the objective of this study was to determine if caspase-3 is responsible for the degradation of myofibrillar proteins during aging. Analysis of western blots revealed no change in abundance of intact troponin-T, desmin, titin, or nebulin over time in myofibrils incubated with caspase-3. However, abundance of these proteins subjected to digestion with mu-calpain and mu-calpain + caspase-3 revealed degradation patterns similar to in vivo samples. No degradation of alpha-actinin was observed in either in vitro or in vivo samples. Results of this study indicate mu-calpain, not caspase-3, is responsible for degradation of specific myofibrillar proteins during beef aging. |
