Prediction of Pork Loin Quality Using Postmortem Temperature and pH Decline Curves

Muscle temperature and pH are the 2 major factors impacting pork quality during the postmortem carcass chilling process. In commercial settings, it is difficult to sort carcasses at an early stage of processing based on meat quality. Therefore, the objective of this study was to develop models to predict loin quality using muscle temperature and pH at selected time points postmortem. Data were collected at 4 different commercial US pork abattoirs with either blast, soft-blast, or conventional chilling (210 total carcasses). Hot carcasses were selected randomly, and temperature and pH measurements were collected in the loin every 1 min from 40 min to 20 h postmortem. Loin quality including pH, color, firmness, and drip loss was evaluated on boneless loins 24 h postmortem. Correlations among temperature, pH, and loin quality were evaluated. Multiple statistical models were explored to predict loin quality using temperature and initial pH or pH up to 360 min postmortem. Results confirm that abattoirs with accelerated temperature decline had reduced rate and extent of pH decline (P < .05), leading to better loin quality with darker color (P < .05) and reduced drip loss (P < .05). Color and 22 h boneless loin pH were moderately correlated with temperature and pH from the mid (360–720 min postmortem) to late (after 720 min postmortem) postmortem period. For quality prediction, the highest correlation was found in the model predicting 20 h bone-in pH using pH at 75, 300, and 360 min and temperature at 345 and 1200 min (r = 0.94). Moderate correlations were observed in models predicting boneless loin pH, color, and drip loss with selected parameters. These data indicate that pork loin quality can be predicted using postmortem muscle temperature and pH. However, commercial application of these models will require abattoir-specific validation to mitigate any variation between commercial settings.