STUNNING METHODS EFFECTS IN ATP DEGRADATION IN REFRIGERATED COBIA (Rachycentron canadum) MEAT

Ninety fish were submitted to 3 stunning methods: electronarcosis (E), CO2 narcosis (C), and hypothermia (H). After this, the animals were killed by gill cut and kept refrigerated at 4 ºC for 21 days. Muscle samples were excised after death (time 0), 5 hours after death and after 1, 7, 14, and 21 days of cold storage for evaluation of ATP degradation. Data were submitted to ANOVA and differences (P<0.05) compared by Tukey test. The time for fish stunning differed between methods: 2s for E, 31 min for C and 17.5 min for H. The initial ATP level observed in C (4.9 µmol g−1) and E (3.57 µmol g−1) was higher than that in H samples (1.71 µmol g−1). AMP was deaminated to inosine monophosphate in all treatments, which showed an increase in this catabolite levels from the 14th storage day. Different stunning methods influenced the speed of degradation and in fish stunned by H this process was slower. Hypoxanthine, formed in adverse handling, presented higher levels in H causing shorter shelf life. Amongst tested methods, E and C presented less detrimental effects on cobia meat quality, when compared to H. Electronarcosis is recomended as stunning method for cobia because, causing fast unconsciousness, it produced a human slaughter and a potential better meat quality.