Avaliação do método de termonarcose na insensibilização de Tilápias do Nilo (Oreochromis niloticus) e o efeito sobre o pH e bases nitrogenadas voláteis totais em filé congelado.

Abstract

The most widely traded food commodity in the world is fish. Because of the progress of fish farming and its importance in the brazilian economy, a greater production and concern with the welfare of the fish has been demanded from the farmers. One of the most important stages in maintaining the quality of the product is slaughter. Also, the lack of animal welfare practices affects the shelf life of the meat, and thus influences its quality. In Brazil, most of the slaughterhouses use thermonarcosis as method of stunning before the slaughter. However, this practice is not currently standardized. The objective of this work was to analyze the thermonarcosis as a stunning method in Nile Tilapia (Oreochromis niloticus) and the effect on pH and total volatile nitrogenous bases in frozen fillet. A total of 60 Nile Tilapias were used, with average weight of 650g and average length of 29,72cm. Ice-water mixture in a 1:1 ratio was used to evaluate the thermonarcosis. Six temperature ranges were tested: group 1 (0 to 1º C), group 2 (1 to 2º C), group 3 (2 to 3º C), group 4 (3 to 4º C), group 5 (4 to 5º C), and group 6 (5 to 6º C). The fish in groups 1, 2, and 3, showed faster loss of consciousness (p<0,001). No changes were observed in the characteristics of the fillets in relation to pH (6,86 to 7,00) and Total Volatile Nitrogen Bases (6,36 to 8,61 mg N/100 g), being in accordance with the parameters stipulated by the current legislation. The temperature range between 0 and 3º C among those evaluated was the one that presented the shortest time for the stunning of Nile Tilapia.