The effects of ultimate pH and color on sensory traits of pork loin chops cooked to a medium-rare degree of doneness.

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 pH of 5.36 through 6.23 were used. Previously, ultimate pH was correlated with sensory characteristics of chops cooked to a medium (71 °C) degree of doneness. Additionally, increasing ultimate pH improved sensory tenderness and juiciness of loin chops cooked to a medium degree of doneness. However, in 2011, the United States Department of Agriculture Food Safety and Inspection Service reduced the recommended final internal cooking temperature of pork chops from 71 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, 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. On 1-d postmortem, loins were evaluated for CIE instrumental L*, a*, b*, visual color, marbling, and subjective firmness. Then, loins were aged in vacuum packages at 4 °C until 16-d postmortem. After aging, loins were cut into 2.54-cm thick chops, vacuum-packaged, and frozen until sensory or instrumental tenderness analysis. One chop was also used to determine extractable lipid. 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. Coefficients of determination (R2) were calculated to determine the predictability of ultimate pH and instrumental color on sensory tenderness, juiciness, and flavor. A 1-way ANOVA and means separation test were used to determine specific differences among pH categories. Ultimate pH explained less than 5% of the variation in tenderness and less than 1% of the variation in juiciness or flavor. Furthermore, sensory tenderness did not differ (P > 0.05) among pH categories, except for chops with an ultimate pH > 5.95. Chops with a pH > 5.95 were at least 9.1% more tender (P < 0.05) than chops with a pH < 5.95. Visual and instrumental color were not predictive (R2 ≤ 0.03) of any sensory traits. Overall, pH does not influence sensory traits of pork chops cooked to medium-rare degree of doneness unless pH is at least 5.95.