The effect of halothane genotype on porcine meat quality and myoglobin autoxidation

Lorraine Git-Ying Tam, Purdue University

Abstract

The effect of halothane genotype (NN, Nn, nn) and slaughter weight (88-286 lb) on porcine meat quality was investigated. Nn and nn genotypes exhibited increased muscularity and decreased fat deposition. Nn and nn pigs 220-286 lb showed increased expression of the HAL gene. Differences between genotypes were maintained across slaughter weights. Longissimus pH$\sb{45}$ for Nn pigs 88-176 lb was intermediate in value (p $<$ 0.01) compared to NN and nn Longissimus $\rm pH\sb{45}$. Longissimus NPPC color score decreased and Hunter L$\sp*$-value increased for nn 88-176 lb indicating a reduction in color; NPPC firmness-wetness score decreased (p $<$ 0.05) and exudativeness increased (p $<$ 0.01) indicating softer and more watery meat than Nn Longissimus. Longissimus $\rm pH\sb{45}$ for Nn pigs 220-286 lb was intermediate in value (p $<$ 0.01) compared to NN and nn Longissimus $\rm pH\sb{45}$. The reduction in Nn Longissimus pH$\sb{45}$ compared to NN was accompanied by a reduction in NPPC color score (p $<$ 0.01) and therefore a less red color. Nn Longissimus Hunter L$\sp*$-value (p $<$ 0.01) and water holding capacity (p $<$ 0.05) were similar to NN. Genotype was highly correlated with Longissimus $\rm pH\sb{45}$ ($-$0.71) and moderately correlated to NPPC color score ($-$0.55), L$\sp*$-value (0.47), water holding capacity (0.42) and NPPC firmness-wetness score (0.51) for pigs 220-286 lb. A three dimensional model describing porcine meat quality was developed based on correlation coefficients between $\rm pH\sb{45}$ and genotype and meat quality parameters. A significant increase (p $<$ 0.05) in rate constant for metmyoglobin accumulation was observed between NN (0.0639 hr$\sp{-1})$ and nn (0.0797 hr$\sp{-1}$) genotypes. The rate constant for metmyoglobin accumulation and oxymyoglobin autoxidation increased (p $<$ 0.05) with decreasing pH. Porcine myoglobin was separated from other muscle components by electrofocusing and two bands of MW $17\times 10\sp3$ were identified at pI 6.1 and 6.5; identical banding patterns were observed between NN, Nn and nn genotypes.

Degree

Ph.D.

Advisors

Okos, Purdue University.

Subject Area

Livestock

COinS