Electrical stunning, hot boning, and quality of chicken breast meat

Centro de Tecnologia de Carnes, Instituto de Tecnologia de Alimentos, Campinas, SP, Brazil.

The first experiment was conducted to determine the effects of varying voltage, 20, 40, 80, and 100 V at 60 Hz, on stunning efficiency, blood loss, and carcass defects. In the second experiment, the same parameters were evaluated to determine the effects of varying frequency, 60, 200, 350, 500, and 1,000 Hz at 40 V. A control group for both experiments was not stunned. At 40V, 30 to 50 mA, 90% of the birds were unconscious, as shown by no response to comb piercing, and blood loss was maximized (55.3%). When varying the stunning frequency, maximum blood loss (73.1%), 90% of the birds were unconscious, and minimum carcass defects were observed at 1,000 Hz, 40 V. In the third experiment, birds were stunned at 40 V, 1,000 Hz and deboned immediately after defeathering (hot boning) and chilled or deboned after passing through all stages of a commercial abattoir operation (conventional boning). Control lots were unstunned and followed normal abattoir stages. Average shear value was significantly lower for stunned compared to unstunned birds (6.0 vs. 7.1 kg/g), although tenderness scores, as measured by a trained panel, were not significantly different (6.6 for stunned birds vs. 6.1 for unstunned). Scores for juiciness were also not significantly different (5.5 for stunned vs. 5.8 for unstunned). Average shear value was also significantly lower for conventionally boned birds (5.2 kg/g) than for hot boned birds (7.9 kg/g). Sensory analysis confirmed the shear value results. Conventionally boned breasts had an average tenderness score of 7.4 vs. an average of 5.3 for hot boned breast. No statistical differences were observed with respect to juiciness, although a score of 6.2 was observed for conventionally boned breast meat vs. a score of 5.1 for hot boned breast meat.