Early Postmortem Prediction of Meat Quality Traits of Porcine Semimembranosus Muscles Using a Portable Raman System

Modern abattoirs are lacking objective, fast, and noninvasive methods to measure or predict important meat quality traits such as pH, color, drip loss, or shear force early postmortem. In this work, a mobile Raman system was used to perform measurements under real-life conditions in the cooling room of an abattoir using pig's semimembranosus muscles (N = 96), 60–120 min after exsanguination. The traits pH₄₅, pH₂₄, CIE L*a*b*, drip loss, and shear force after 24 and 72 h were measured as reference and correlated with the Raman spectra using partial least squares regression. Strong correlations of the Raman spectra were obtained for pH₄₅ (R ² cᵥ = 0.65, RMSECV = 0.17 pH units), pH₂₄ (R ² cᵥ = 0.68, RMSECV = 0.09 pH units), L*-value (R ² cᵥ = 0.64, RMSECV = 1.9), b*-value (R ² cᵥ = 0.73, RMSECV = 0.6), drip loss (R ² cᵥ = 0.73, RMSECV = 1.0 %), and shear force after 72 h (R ² cᵥ = 0.7, RMSECV = 4 N). On the other hand, shear force after 24 h and a*-value showed only weak correlations (R ² cᵥ = 0.22, RMSECV = 7.8 N and R ² cᵥ = 0.36, RMSECV = 1.3). The predictions can be traced back to differences in the early postmortem metabolic conditions as indicated by Raman signals of phosphocreatine, creatine, adenosine triphosphate, inosine monophosphate, glycogen, lactate, phosphorylated metabolites, and inorganic phosphate. This study demonstrates the potential of Raman spectroscopy for the early postmortem prediction of six pork quality traits which can be useful for the discrimination of meat qualities and sorting in the production chain.