pH measurements in the slaughterline and carcass quality: a survey in six Belgian slaughterhouses

pH was measured early post mortem in longissimus muscle (and occasionally in semimembranosus muscle) in the slaughterline of six Belgian slaughtering plants in three or four sessions. Mean pH values differed according to the mode of expression: pH means calculated after transformation to hydrogen ion concentrations were always lower than means calculated directly from pH values. The differences was linearly dependent on the variance, meaning that transformation of pH values to hydrogen ion concentrations is strongly recommended when comparing mean values of groups with unequal variances. Large differences in pH means were found between slaughterhouses that could not be attributed to differences in time of measuring postmortem and that were probably not related to differences in the slaughtering procedure. On the other hand, negative relationships were apparent between carcass quality data (lean content and instrumental or visual conformation score) and pH values between as well as within all slaughtering plants. Although no exact information was available on the preslaughter treatment of the animals, it is suggested that the genetic antagonism between carcass quality and meat quality is the main source of the fairly high proportion of low initial pH values and inferior meat quality in Belgian slaughter pigs