Effects of heat exposure on muscle oxidation and protein functionalities of pectoralis majors in broilers.

This study was conducted to determine the effects of heat stress on pH, lipid peroxidation, protein oxidation, and functionalities of breast meat in broilers. The experimental birds were exposed to 2 temperatures: 24 degrees C (control) and 41 degrees C (heat-stressed) for 0, 1, 2, 3, and 5 h. As compared with control, the pH determinations after slaughter for 30 min and 24 h of chilling, respectively, of the pectoralis major in the heat-stressed groups were significantly lower (P < 0.05). Oxidative stability of i.m. lipid in 3- and 5-h groups (P < 0.01) and protein in 2-, 3-, and 5-h groups (P < 0.01) increased. Protein solubility of pectorilas major decreased after heat exposure. Drip loss and cooking loss were increased in groups from 1 to 5 h of exposure. A reduced strength was noted for myofibrillar protein gels of heat-stressed breasts in exposed groups (P < 0.01); also water-holding capacity of the gels was reduced in treatments of 2, 3, and 5 h (P < 0.01). The results demonstrated that preslaughter exposures to heat reduced the oxidative stability of broiler muscle protein, which might be responsible for decreased protein functionalities such as gelation.