1a.Objectives (from AD-416):
Determine the temperature and pH profiles for optimal quality of modern pork.
1b.Approach (from AD-416):
Four pork processing plants that represent both conventional and blast chilling will be sampled twice, once in summer and once in winter. Within each day of sampling, test carcasses will be taken from early, mid, and late time points within the harvest shift to represent the diversity of blast and batch chilling conditions that occur throughout the day. In total 960 carcasses will be tested (120 carcasses per day × 2 sampling days/plant × 4 plants). Hot carcass weight, fat thickness, deep loin and deep ham temperature decline, loin pH decline will be recorded for each test carcass. The ham and the loin will be obtained from the left side of each carcass. Color of the ham face will be assessed visually and instrumentally. Loins will be deboned and trimmed, vacuum-packaged and aged until 14 days postmortem. Purge loss will be measured and two loin chops will be cut and cooked for LM slice shear force measurement. Remnants of the slice will be frozen for subsequent measurement of sarcomere length and postmortem proteolysis.
Pork processing collaborators could not be identified for this project, so the objective was changed to evaluate biochemical traits related to beef lean color stability. Insufficient color-life of meat products is a problem that costs the meat and livestock industries $1 billion annually. Many of the enzyme systems known to influence lean color stability of meat products are located in the mitochondria of muscle cells. Site specific defects in the electron transport chain have been demonstrated to cause oxidative conditions in muscles cells, and reduce feed efficiency in meat producing species. Mitochondrial inefficiency was hypothesized to affect lean color stability in meat products. Lean color stability, reducing capacity, and mitochondrial efficiency (electron loss) were determined on beef ribeye muscles. Greater electron loss is associated with decreased reducing capacity and, consequently, decreased beef lean color stability. These results indicate that mitochondrial efficiency influences lean color stability in meat products, and technology targeting the improvement of mitochondrial efficiency could improve lean color stability of meat products. Furthermore, genetic selection for increased feed efficiency may also improve lean color stability.