Impact of divergent selection for ultimate pH of pectoralis major muscle on biochemical, histological, and sensorial attributes of broiler meat

The impact of divergent selection based on the ultimate pH (pHu) of pectoralis major (P. major) muscle on the chemical, biochemical, and histological profiles of the muscle and sensorial quality of meat was investigated in broiler chickens. The protein, lipid, DM, glycogen and lactate content, glycolytic potential, proteolysis, lipid and protein oxidation index, muscle fiber cross-sectional area, capillary density, and collagen surface were determined on the breast P. major muscle of 6-wk-old broilers issued from the high-pHu (pHu+) and low-pHu (pHu-) lines. Sensory attributes were also evaluated on the breast (roasted or grilled) and thigh (roasted) meat of the 2 lines. Protein, lipid, and DM content of P. major muscle were not affected by selection (P > 0.05). However, the P. major muscle of the pHu+ line was characterized by lower residual glycogen (-16%; P <= 0.001) and lactate (-14%; P <= 0.001) content and lower glycolytic potential (-14%; P <= 0.001) compared with the pHu- line. Although the average cross-sectional area of muscle fibers and surface occupied by collagen were similar (P > 0.05) in both lines, fewer capillaries per fiber (-15%; P <= 0.05) were observed in the pHu+ line. The pHu+ line was also characterized by lower lipid oxidation (thiobarbituric acid reactive substance index: -23%; P <= 0.05) but protein oxidation and proteolysis index were not different (P > 0.05) between the 2 lines. At the sensory level, selection on breast muscle pHu mainly affected the texture of grilled and roast breast meat, which was judged significantly more tender (P <= 0.001) in the pHu+ line, and the acid taste, which was less pronounced in the roasted breast meat of the pHu+ line (P <= 0.002). This study highlighted that selection based on pHu does not affect the chemical composition and structure of breast meat. However, by modifying muscle blood supply and glycogen turnover, it affects meat acidity and oxidant status, both of which are likely to contribute to the large differences in texture observed between the 2 lines.