Correlation of fresh muscle firmness with sensory characteristics of pork loins destined for a quality focused market

Production of pork for quality-driven export markets offers economic incentive. Pork processors use subjective firmness as a sorting tool for loins intended for high-quality export. The objectives of this study were to determine 1) durometer efficacy in muscle, 2) if firmness on one portion of the loin is indicative of other locations, 3) if 1 d firmness is related to export quality traits, and 4) if variation in firmness is explained by mechanistic measures. Subjective firmness scores (1 = extremely soft and 5 = extremely firm) were determined by a trained individual 1 d (initial time point) postmortem. Loins (North American Meat Processors number 414 Canadian back; = 154) were wet aged for 28 d at 1.7°C. On d 28, a panel of 4 individuals assigned firmness scores on the ventral side of the loin at the area of the 10th rib, the anterior half, and the posterior half of the loin. Durometer readings were collected at the area of the 10th rib on the dorsal and ventral side of the loin. Spearman correlation coefficients were computed in SAS (version 9.3) to account for nonnormality of categorical data. Subjective firmness measurements at d 28 at the 10th rib and on the anterior portion of the loin were not correlated ( ≥ 0.21) with whole loin durometer readings on the dorsal or ventral portion of the loin or the average of the whole loin values. Subjective firmness (d 28) at the 10th rib accounted for 38.44 ( = 0.620) and 48.30% ( = 0.695) of the variation in firmness at the anterior portion of the loin and the posterior portion of the loin, respectively ( ≤ 0.05). One-day subjective firmness measurements were correlated with 28-d Warner-Bratzler shear force measurements ( = 0.174, = 0.03) but were not significantly correlated with sensory characteristics ( ≥ 0.08). Purge tended to be correlated with 1 d firmness ( = 0.136, = 0.10); however, drip and cooking loss, 24-h and 28-d pH, and soluble and insoluble collagen content were not correlated ( ≥ 0.34). Firmness measurements collected in the production facility (1 d) were negatively correlated with iodine value (IV; = -0.199, = 0.02), yet no 28-d subjective firmness measurements were correlated with IV ( ≥ 0.33). When loins not achieving export standards are removed from the population, 1 d firmness was not correlated to export quality or sensory characteristics (d 28). Differences in firmness were not explained by mechanistic measures. Inconsistencies among subjective and objective firmness measurements suggest that the durometer may not be an appropriate way to determine firmness.