Effect of stunning amperage on broiler breast muscle rigor development and meat quality

Two experiments were conducted to determine the effects of constant amperage (as opposed to constant voltage) electrical stunning on broiler blood loss, post-mortem breast muscle (Pectoralis major) rigor development, and breast meat quality. Broilers were individually stunned for 5 s at 0 (unstunned control group), 50, 100, 150, and 200 mA in Experiment 1 and at 0, 50, and 125 mA in Experiment 2. Breast muscle pH and R-value (ratio of adenosine to inosine nucleotides) were determined at 15 min and 24 h post-mortem; breast meat shear value and color were determined at 48 h post-mortem. Stunning amperage had no effect on percentage blood loss in either experiment. The most rapid post-mortem reactions were observed for the unstunned control group as determined by pH and R-value at 15 min post-mortem. Birds stunned with 50 mA were intermediate with regard to rate of rigor development. The slowest post-mortem reactions occurred in broilers stunned from 100 to 200 mA. There were no differences in pH, R-value, or color between stunning treatments after carcasses were aged for 24 h. Stunning amperage did not affect Allo-Kramer shear value for breast muscles deboned at 15 min post-mortem. In Experiment 2, 24 h aged breast meat from broilers stunned with 125 mA required significantly higher shear value (4.5 kg/g) than breast meat from broilers stunned at 0 or 50 mA (3.8 and 3.6 kg/g, respectively). Results indicate that stunning amperages between 0 and 200 mA had effects on the rate of early rigor development but there were no consistent effects on final breast meat quality.