Effect of different slaughter methods on quality of Oreochromis sp. fillets

To improve the flesh quality of tilapia, we studied the effects on flesh quality of tilapia by different slaughter methods. Tilapia were slaughtered by four different methods as follow: (Ⅰ) bleeding followed by immersion in ice/water slurry for 20 minutes, (Ⅱ) immersion in ice/water slurry for 20 minutes, (Ⅲ) percussive stunning, (Ⅳ) percussive stunning followed by bleeding and immersion in water for 20 minutes. TVB-N values, Ca2+-ATPase activity, color and texture profile analysis (TPA) were measured during iced storage. The results show that TVB-N values of four groups increase signally, and Ca2+-ATPase activities of four groups decrease obviously during iced storage. TVB-N values in group Ⅱand Ⅲ are significantly lower than that in group Ⅰ and Ⅳ. Group Ⅱand Ⅲ are benefit for retaining freshness during iced storage, while group Ⅲ and Ⅳ are conducive to maintaining Ca2+-ATPase activity. Fillets of group Ⅱand Ⅲ become paler than that of group Ⅱand Ⅲ, and fillets of group Ⅱand Ⅲ have higher redness than groupⅠand Ⅳ. Hardness, chewiness and gumminess in fillets of four groups decreased significantly during iced storage. Texture quality in group Ⅲ maintains better than that in other groups. In conclusion, percussive stunning is the optimum to kill tilapia in the four methods.