New frontiers in understanding drip loss in pork: recent insights on the role of postmortem muscle biochemistry

The aim of this review was to summarize some of the most important and novel hypotheses regarding the development of water-holding capacity in pork. Among the key factors that determine water-holding capacity are rate and extent of pH decline and the structure of the muscle and the muscle cell itself. However, there have been numerous reviews on the importance of pH yet relatively few on the concept of how muscle cell structure influences the ability of the postmortem cell to maintain water/moisture. Recent advances in the ability of scientists to monitor the movement of water within the cell and within the muscle and to monitor protein degradation have led to new hypotheses regarding the development of drip or purge from fresh meat. One of the more novel and promising hypotheses that has surfaced recently is that alterations in the architecture of the cell may govern the retention/loss of moisture from the muscle cell and ultimately the muscle. The degradation of cytoskeletal and intermediate filament proteins (like desmin) early postmortem may release constraints within the cell that limit the space available for water/fluid that has been forced from the myofibril during rigour. Conversely, degradation of some membrane proteins (like integrin) could actually contribute to the formation of drip channels and thus might actually improve the ability of moisture to 'escape' from the muscle cell. Thus, water-holding capacity in fresh meat is associated with specific changes that occur in early postmortem muscle.