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 C and loin tenderness was assessed as Warner–Bratzler shear force (WBSF). Cooked temperature
(P < 0.001), breed (P < 0.001) and breed 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 C. In loins from Landrace pigs, Minolta a* at 62 C
(R2 = 0.07), and average muscle fiber diameter at 71 C and 79 C (R2 = 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 C and 71 C, respectively, and
loin ultimate pH accounted for 7% of variation in WBSF at 79 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.