Phosphorproteome Changes of Myofibrillar Proteins at Early Post-mortem Time in Relation to Pork Quality As Affected by Season

The
effect of season on phosphorylation of myofibrillar proteins
and meat quality of pork longissimus muscles was
investigated. Muscle samples were obtained from 40 pork carcasses
(10 for each season) at 45 min and 3 and 9 h post-mortem. Myofibrillar
proteins were extracted, separated by SDS-PAGE, quantified by phosphor-specific
staining, and finally identified by LC-MS/MS. Muscle pH, glycogen,
and ATP were measured, and pale, soft, and exudative (PSE) meat was
identified by pH value at 45 min post-mortem. A total of 23 bands
were detected on SDS-PAGE gels. The phosphorylation levels of bands
did not differ between PSE and normal meat. However, the phosphorylation
levels of 22 bands were significantly changed by season. Nine of them
showed different changes from 45 min to 9 h post-mortem, which were
identified to be involved in energy metabolism and sarcomere contraction.
Correlation analysis indicated the regulatory progress of these proteins
during rigor mortis. These observations contribute to a better understanding
of the biochemical processes for the conversion of muscle to meat
varying with season.