It has been well-documented that both ultimate pH and instrumental color are correlated with the sensory characteristics of pork loin chops cooked to a medium (71˚C) degree of doneness. In addition, consumers use color more than any other meat quality trait to determine purchase intent. Furthermore, increasing ultimate pH positively influenced both sensory tenderness and juiciness scores when chops were cooked to 71˚C. However, in 2011, the USDA Food Safety and Inspection Service reduced the recommended final internal cooking temperature of pork chops from 71°C to 63°C (followed by a 3 min rest). The effects of ultimate pH on sensory traits of pork chops cooked to a medium-rare (63°C) degree of doneness are not known. Therefore, the objective was to determine the effects of pH and color on sensory characteristics of boneless pork loin chops cooked to an internal endpoint temperature of 63˚C. Center cut loins (296 total) from barrows and gilts, 5 different sire lines, and a range in ultimate pH of 5.36 – 6.23 were used. Loins were categorized using historical categories based on ultimate pH: >5.95, n = 22; 5.80 to 5.95, n = 75; 5.65 to 5.80, n = 102; 5.50 to 5.65, n = 91; <5.50, n= 6. Loins were then evaluated for CIE instrumental L*, a*, b*, NPPC visual color, NPPC visual marbling, and subjective firmness on 1 d postmortem. All measurements were collected on the ventral surface of the loin at the approximate location of the 10th rib. Then, loins were transported to the University of Illinois Meat Science Laboratory and aged in vacuum packages at 4°C until 16 d postmortem. At 16 d postmortem, the same quality measurements were recorded and loins were sliced into 2.54 cm thick chops. Chops were then vacuum packaged and frozen until further analyses. One chop was also used to determine extractable lipid. The second chop was used to evaluate instrumental tenderness. These chops were weighed, cooked to 63°C, cooled to approximately 23°C, weighed again to determine cook loss, and then evaluated for Warner-Bratzler shear force. Another chop was cooked to 63°C internal temperature and served warm to trained panelists to determine sensory traits. Trained sensory panels consisted of six individuals that evaluated pork chop tenderness, juiciness, and pork flavor. Panelists were selected from a pool of experienced, trained students and faculty from the University of Illinois (Champaign-Urbana, IL).Coefficients of determination (R2) were calculated to determine the predictability of ultimate pH and instrumental color on sensory tenderness, juiciness, and flavor. Ultimate pH explained 5% of the variation (R2 = 0.05, P < 0.001) in trained sensory tenderness scores. However, ultimate pH was not an effective predictor of trained sensory juiciness or flavor scores as it explained less than 1% (R2 < 0.01; P = 0.10) of the variation in panelist scores. Ultimate pH was also not predictive (R2 < 0.01, P = 0.34) of Warner-Bratzler shear force (WBSF). Furthermore, NPPC visual color score explained less than 1% (R2 < 0.01, P = 0.83) of the variation in sensory tenderness, juiciness, and flavor scores or WBSF and, therefore, was not an effective predictor of eating quality. In addition, instrumental L*, a*, and b* explained at most 3% of the variation in tenderness and juiciness scores. Finally, the combination of ultimate pH, instrumental L*, instrumental a* and instrumental b*accounted for 11% (R2 = 0.11, P < 0.0001) of the variation in sensory tenderness scores, but was not at all predictive of sensory juiciness or flavor scores (R2 ≤ 0.01, P ≤ 0.13). Overall, ultimate pH does not independently influence eating quality (tenderness, juiciness, and flavor) of boneless pork loin chops cooked to a medium-rare degree of doneness (63°C) unless pH is at least 5.95.
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The effects of ultimate pH and color on sensory traits of pork loin chops cooked to a medium-rare degree of doneness
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