Assessment of postmortem proteolysis by gel-based proteome analysis and its relationship to meat quality traits in pig longissimus

This study was conducted to assess postmortem proteolysis using a proteomics approach, and to determine the relationship of proteolysis to WB-shear force, drip loss, and hunter L* value during chiller ageing in pig longissimus muscle. To generate various meat qualities, 20 male landraces were assigned into 2 × 2 factorial (10 pigs fasted for 18 h and 10 pigs fed until the morning of slaughter × 20 sides placed at -3°C and 20 sides at 6°C). An interaction between muscle temperature at pH 6.2 (TpH6.2) and ageing for both WB-shear force and drip loss showed that a high TpH6.2 produced meat with a lower shear force, but the advantage was gradually eroded by extended ageing (i.e., 1, 3 and 7 d). On the other hand, the detrimental effect of a high TpH6.2 on drip loss became more apparent as ageing time increased (i.e., 3 and 7 d). Changes in the objective quality traits and semi-quantitative spot density for 27 out of 133 identified proteins coincided during ageing. The proteins included myosin light chain 1, desmin, troponin T, cofilin 2, F-actin capping protein β subunit, ATP synthase, carbonate dehydratase, triosephosphate isomerase, actin and its relevant peptides, peroxiredoxin 2, α-b crystalline and heat shock protein 27 kDa.