488 Postmortem muscle protein degradation and meat quality.

Abstract

Postmortem conversion of muscle to meat consists of complex biochemical mechanisms that influence meat quality. Energy metabolism and pH decline are the drivers behind quality attributes such as water-holding capacity, tenderness, and color stability. However, additional processes such as proteolysis and protein oxidation and phosphorylation also have significant roles during the aging period and contribute to quality variability. Much of the research on postmortem muscle protein changes has concentrated on degradation of myofibrillar proteins with major changes being observed through fractionation of proteins along the z-line of the sarcomere. Ultimately, these structural changes have significant impacts on tenderness as well as water-holding capacity in terms of steric and net-charge effects. However, causes of the inconsistencies in protein degradation are not completely understood. In the last decade, proteomic analysis has provided insight into these variations in postmortem protein degradation as orchestrated by proteolytic systems such as calpains, caspases, proteasome, or cathepsins. Through proteomics, protein degradation has been linked with energy metabolism (appearance of fragmented glycolytic and oxidative enzymes), cellular death cascades (apoptosis or autophagy), cellular survival (heat shock and chaperone proteins), and oxidative stress. Elucidation of these processes and their impacts on postmortem muscle proteins, as well as their inherent interactions, are key to understanding the mechanisms of meat palatability attributes and providing biomarkers that could be utilized by all facets of livestock production.