EFFECT OF HALOTHANE GENOTYPE ON PORCINE MEAT QUALITY AND MYOGLOBIN AUTOXIDATION

The objective of this study was to determine effects of light (40-80 k g) or heavy (100-130 kg) slaughter weight and halothane status (positi ve, nn; negative, NN; and heterozygous, Nn) on meat quality. Longissim us muscle (LM) pH at 45 min (pH(45)) post-exsanguination was 6.25, 6.0 3, and 5.84 (different at p<0.01) for NN, Nn, and nn genotype, respect ively. At heavier weights (100-130 kg), genotype correlated (r = -0.71 ) with LM pH(45), 10th costae LM (TENLM) color score (r = -0.55), TENL M Hunter L-value (r = 0.47), water holding capacity (r = 0.42) and TE NLM subjective firmness-wetness score (r = 0.51). Rate constants for m etmyoglobin accumulation and oxymyoglobin autoxidation, indicators for fresh meat color stability, increased (p<0.05) with decreasing pH. Co lor stability for NN muscle was more stable than nn muscle (p<0.05). E lectrofocusing of myoblobin revealed two bands (MW 17.10(3)) at pI 6.1 and 6.5 across genotypes. Because differences were not observed acros s genotypes, an observed increase (p<0.05) in 24 hr myoglobin autoxida tion rate constant (associated with increased expression of the HAL ge ne) are presumed dependent upon post-mortem muscle changes. These data show that changes in halothane status affect fresh pork quality and t hat lowered meal quality results in further color destruction due to a ltered chemical reactions involving myoglobin oxidation. (C) 1998 Else vier Science Ltd. All rights reserved.