Processing Characteristics of Porcine Muscle Related to pH and Temperature During Rigor Mortis Development and to Gross Morphology 24 hr Post‐Mortem a, b, c

SUMMARY pH and temperature in muscle during the onset of rigor mortis as well as gross morphology of muscle 24 hr post‐mortem were related to fluid losses and associated properties during refrigerated storage, cooking, and thawing. When rigor mortis onset occurred at pH values below 5.9 and temperature above 35°C, the longissimus dorsi muscle became pale and exudative. Evaporative cooking losses amounted to 40–45% of the sample weight and resulted in slow cooking rates and high shear‐force values. Conversely, when the onset of rigor mortis occurred while pH values remained above pH 6.0 the muscles were dark and firm, with superior juice‐retaining properties. Less than 20% of the sample weight was lost by evaporation during cooking, allowing the muscle temperature to rise at about twice the rate found for pale exudative muscle. Some muscles were found to be exudative and have low pH values (5.2) while retaining a dark red color. These muscles were found to have storage, cooking, and organoleptic properties similar to those found for pale exudative muscle. Storage of muscle samples at either 0°C or 6°C did not improve color, pH, juice retention or cooking characteristics. Gross morphology of muscle chilled 24 hr was associated more closely with thaw drip formation than with freezing or thawing conditions.