Effects of Different Slaughtering Methods on Rigor Mortis, Muscle pH and Blood Variables of selected fish species

Abstract:

Quality of fish as raw material is partly predicated on the stress it passes through before death and method used of fish slaughtering also contribute to it. Effect of different slaughtering methods on rigor mortis, muscle pH and blood hematological variables were investigated. Slaughtering methods employed include: percussive stunning, salt stunning, ice slurry asphyxia and electrical stunning methods. 10 Clarias gariepinus and Heteroclarias each was used for the study. C. gariepinus and Heteroclarias had a pH range of 7.1 -7.4 and 6.9 – 7.2 respectively. No significant difference (P < 0.05) exist in the glucose, sodium, chloride, potassium, osmolality, lactate and cortisol concentration of the C. gariepinus slaughtered using the stunning methods while the highest concentration of urea (2.65±0.07) was observed in the blood of fish killed by ice slurry asphyxia. There was significant difference (P < 0.05) in the urea concentration (4.85±0.07) of Heteroclarias killed by ice slurry asphyxia followed by that slaughtered using salt stunning method (4.30±0.14). Heteroclarias killed using electrical stunning method recorded the highest glucose (7.40±1.27) in its blood which could be as a result of the stress it passed through. The study concluded that killing fish using ice slurry asphyxia impacted more stress on the fish, followed by electrical stunning method. Further research using large sample size is hereby recommended.