Effect of the genotype for malignant hyperthermia as determined by a restriction endonuclease assay on the quality characteristics of commercial pork loins.

A total of 913 boned pork loins were selected in a commercial cutting operation on the basis of color measured by a Colormet surface colorimeter. Color (L, a, b values) at three locations, free water, and ultimate pH were measured on each loin. In addition, the genotype with respect to malignant hyperthermia was determined by a restriction endonuclease assay. Six hundred ninety-three loins were determined to be of normal (NN) genotype, 198 heterozygote (Nn), and 22 homozygote (nn). This distribution reflected the selection strategy and not the incidence in the general population. Meat was darker (P < .01) and free water was reduced (P < .01) in NN loins compared to Nn or nn loins. Ultimate pH was lower (P < .01) in Nn loins than in NN loins. An increase in the incidence of Nn or nn meat samples was observed as the paleness of the loins or their free water content increased, or as the ultimate pH of the meat decreased. Based on this study, approximately 30% of meat classified as PSE on a color basis would come from heterozygote pigs.