THE MEASUREMENT OF LIGHT-SCATTERING AND ELECTRICAL-CONDUCTIVITY FOR THE PREDICTION OF PSE PIG MEAT AT VARIOUS TIMES POST-MORTEM

Measurements of light scattering and electrical conductivity were made in the Longissimus dorsi (LD) and Semimembranosus (SM) muscles using the Fibre Optic Probe (FOP) and Quality Meter (QM), respectively, to assess their ability to estimate pig meat quality, particularly the occurrence of PSE meat. One-hundred-and-fifty-three gilt carcasses were measured on three occasions post mortem (pm): 45 min (FOP45 and QM45), 2h (FOP2 and QM2 and 24 h (FOPu and QMu). Measurements of pH were taken in the same anatomical position and at the same times. At 24 h pm muscle reflectance (GOFO value) and subjective colour assessments were made on the cut surface of the LD at the level of the last rib. Water-holding capacity (WHC) was estimated in a sample taken from the exposed surface of the LD by the solubility of sarcoplasmic and myofibrillar proteins. The FOP45 predicted most accurately the WHC (R2 = 0·49). Neither of the other quality measurements improved the prediction at 45 min pm. However, at 2h, adding QM2 as a second independent variable improved prediction of WHC (R2 = 0.58). At 24 h the combination of FOPu, QMu and GOFO did not improve the prediction of WHC (R2 = 0.58). The best prediction used measurements of FOP45, QM2 and GOFO (R2 = 0·62). The best relationship between subjective colour scores and the quantitative measurements of meat quality using discriminant analysis was obtained with the FOPu with an error-count estimate of 15·1% followed by FOP2 (17%), GOFO value (18·7%), pH2 (19·7%) and QMu (20·2%). With combination measurements of two instruments, pH2 and FOP2 had the lowest error-count estimate (10·9%). No further precision was obtained with combinations of three instruments. These results suggest that FOP and QM can be used to predict PSE and normal pig meat at different times pm and can replace traditional pH muscle measurements. © 1990.