Effect of Slaughter Methods on Quality of Frozen Channel Catfish Fillets
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Abstract:
To improve the quality of frozen fish fillet, different slaughter methods were evaluated to determine their effect on the quality of frozen channel catfish. Fresh channel catfish were slaughtered by four methods (carbon dioxide stunning, electrical stunning, percussive stunning, and bleeding in ice slurry) and fillets were stored in a refrigerator at -18 ℃. The pH value, color, hemoglobin content, drip loss, total volatile base nitrogen (TVB-N), and bacterial counts in each group were evaluated. Muscle pH values showed an upward trend after an initial decline at 45-h post-mortem; the change in pH value for bleeding-in-ice-slurry group was the smallest, followed by percussive-stunning group; whereas the largest pH change was found in CO2-stunning group. The a* and L* values for the bleeding-in-ice-slurry group were significantly different from those for other groups (p < 0.05), whereas less blood was retained in the bleeding-in-ice-slurry group (p < 0.05). During the 60-day storage period, highest drip loss (5.53%) was observed for the CO2-stunning group (p < 0.05), while the lowest (3.25%) was found for the percussive-stunning group. The lowest TVB-N value was found for the bleeding-in-ice-slurry group (p < 0.05), with no significant differences among other three groups (p < 0.05). The bacterial count exhibited a declining trend during storage and the lowest count was found for the bleeding-in-ice-slurry group, followed by percussive-stunning, CO2-stunning, and electric-stunning groups. Thus, fish slaughter by bleeding in ice slurry and percussive stunning produce good-quality fillets of frozen channel catfish.
