Muscle biomarkers to differentiate pork quality categories based on industry and consumer demands

Pork quality is a complex phenotype assessed by a combination of physical, biochemical, and occasionally sensory indicators measured one or even few days after slaughter using generally costly and/or invasive analyses. Early post-mortem (p.m.) biomarkers of pork quality have been identified by functional genomics however they usually refer to a single indicator and not to the overall quality level of a pork sample. This study aimed at determining pork quality categories combining both sensory and technological dimensions, and at identifying biomarkers discriminating these categories to further develop tools to monitor and predict pork quality in slaughterhouses. Sensory, technological and gene expression data were collected on the longissimus muscle of 100 pigs of two different breeds reared in various production systems and thereby exhibiting a wide and gradual variability in meat quality. Scientific expertise and statistical (multiple correspondence analysis) approaches were combined to select indicators and their thresholds specifying quality categories: low (impaired) quality (L; pH30<6.10 or pH 24 h<5.50, n=37); and among non-defective pork, acceptable (A; drip≥1% or intramuscular fat (IMF)<2.5%, n=26) and extra (E; drip<1% and IMF≥2.5%; n=35). The L category had the highest drip loss and lightness (P<0.001) and the lowest tenderness (P<0.001) and juiciness (P<0.05) scores, whereas E had the highest values of pH30, pH24, red colour and tenderness score (P<0.001). Levels of previously identified biomarkers of single quality traits, determined in longissimus sampled 30 min p.m., highly differed according to quality categories. Two genes were up-regulated (P=0.003) specifically in L, 5 genes were up-regulated (P≤0.007) and 4 down-regulated (P≤0.009) specifically in E, and 2 genes had gradual expression level between L, A, and E categories (P<0.0001). Biomarkers differentiating pork quality categories will be validated on a commercial pig population.