Nitrogen compounds as potential biochemical markers of pork meat quality

Muscle proteins, peptides and free amino acids were analysed at 2 h post-mortem as potential markers of different pork meat qualities. The meat quality classification was based on the measurements: pH2h, pH24h, the colour parameter L, and drip loss. The measurement of proteolytic fragments by SDS-PAGE revealed that the nebulin band was different among classes being more defined in the dark, firm and dry meat class. The detection and characterisation of small peptide fragments resulting from protein breakdown was done by isolation through cationic and reverse-phase chromatography. The analysis of peptide fractions isolated by reverse-phase chromatography revealed that could be used as potential markers of meat quality. So, peptide fraction 1 could be used to distinguish exudative from non-exudative meats and peptide fraction 4 distinguished dark, firm and dry meat from the rest. The concentration of free amino acids present in muscle was not different among qualities, probably due to the early post-mortem time (2 h) used in the study.