Effects of cooked temperature on pork tenderness and relationships among muscle physiology and pork quality traits in loins from Landrace and Berkshire swine.

The effect of, and associations between, loin muscle morphology and pork quality indicator traits were assessed at three cooked temperatures in loin chops from 38 purebred Berkshire and 52 purebred Landrace swine. Three loin chops from each pig were randomly assigned to cooked temperature treatments of 62, 71, or 79 degrees C and loin tenderness was assessed as Warner-Bratzler shear force (WBSF). Cooked temperature (P<0.001), breed (P<0.001) and breed x cooked temperature (P<0.001) effects influenced loin chop WBSF, whereby WBSF increased as cooked temperature increased. Chops from Landrace pigs had greater WBSF at each cooked temperature compared with chops from Berkshire pigs. Chops from Landrace pigs became less tender with increasing cooked temperature, whereas chops from Berkshire pigs became less tender only when cooked to 79 degrees C. In loins from Landrace pigs, Minolta a* at 62 degrees C (R(2)=0.07), and average muscle fiber diameter at 71 degrees C and 79 degrees C (R(2)=0.07 and 0.24, respectively), contributed to WBSF variation. In contrast, for loins from Berkshire pigs, loin ultimate pH and intramuscular fat percentage accounted for 27% and 30% of the variation in WBSF at 62 degrees C and 71 degrees C, respectively, and loin ultimate pH accounted for 7% of variation in WBSF at 79 degrees C. Results suggest that loins from Berkshire pigs have properties that resist toughening at greater cooked temperatures and that associations between quality measures and loin tenderness differ between Landrace and Berkshire pigs.