Impact of electrical stunning on fish behavior and meat quality of pacu (Piaractus mesopotamicus)

Electrical stunning is considered one of less stressful fish stunning method. However, for its efficiency, it is important to determine the best way of application of the electrical variables. The aim of this study was to evaluate the effect of different voltages (100, 150, and 200 V) of alternating current (AC) or direct current (DC), frequency of 50 Hz, for 180 s exposure, concerning the aspects of behavior and meat quality of pacu (Piaractus mesopotamicus). Fish subjected to AC remained unconscious longer, evaluated by behavior analysis, when compared to DC. The pacu subjected to 100 AC, 200 AC and 100 DC showed less bleeding in the fillets. The lightness ([L.sup.*]) of the fillets were higher in 150 AC, 150 DC and 100 DC, followed by 200 and 100 AC. The redness ([a.sup.*]) in pacu fillets were moderate in treatments 200 and 150 AC and less intense in treatments 100 DC and 100 AC. The yellowness ([b.sup.*]) was higher in fish fillets treatment 150 DC and lower in 100 AC. Therefore, the 200 V alternating current (AC) used in water stunning caused apparent unconsciousness of up to 4 min. after exposure and less bleeding in fillets, thus it is a suitable stunning method to be recommended for the pacu processing industry. Keywords: fillets color, slaughter, native species, fish. O atordoamento eletrico e considerado um dos metodos de abate de peixes menos estressantes. No entanto, para eficiencia deste metodo, e importante determinar a melhor combinagao de variaveis eletricas. O objetivo deste estudo foi avaliar o efeito de diferentes voltagens (100, 150 e 200 V) de corrente eletrica alternada (CA) ou continua (CC), frequencia de 50 Hz, por 180 s de exposigao, nos aspectos de comportamento e de qualidade da carne de pacus (Piaractus mesopotamicus). Os peixes submetidos a CA permaneceram mais tempo inconscientes, o que foi avaliado pela analise comportamental, do que aqueles submetidos a CC. Os pacus submetidos a 100 CA, 100 CC e 200 CA apresentaram menor hemorragia nos files. A luminosidade dos files ([L.sup.*]) foi maior nos tratamentos 150 CA, 150 CC e 100 CC, seguidos dos de 200 CA e 100 CA. A intensidade de vermelho ([a.sup.*]) nos files dos pacus foi moderada nos tratamentos 200 CA e 150 CA e menos intenso nos tratamentos 100 CC e 100 CA. A intensidade de amarelo ([b.sup.*]) foi maior nos files dos peixes submetidos ao tratamento 150 DC e menor em 100 CA. Portanto, a corrente alternada com 200 V usada no atordoamento de pacus causa aparente inconscienc