Avaliação de diferentes métodos de insensibilização nas respostas de estresse, aspectos comportamentais e qualidade da carne do pintado amazônico (fêmea de Pseudoplatystoma fasciatum x macho de Leiarius marmoratus)

Abstract

This work evaluated different stunning methods effect (carbon dioxide narcosis, ice asphyxia and air exposure) on the stress response and meat quality of Amazon pintado (Pseudoplatystoma fasciatum female x Leiarius marmoratus male). Seventy individuals (1.28 ± 0.45 kg and 54.13 ± 6.20 cm) were submitted to CO2 narcosis (treatment 1), hypothermia (treatment 2) and air exposure (treatment 3), plus a control group (no disturb). After the application of the treatments above, the fish were tagged using microtransponders and bled to physiologic parameters analyses. After measuring the weight and length, the fish were sacrificed by gill cutting, gutted and then followed for post mortem pH, rigor mortis, meat water-holding capacity and coloration (L,a,b). After air exposure, the fish presented cortisol and glucose levels significantly higher when compared with other treatments. No significant differences were observed within treatments for hemoglobin, total protein, chloride, lactate dehydrogenase and creatinine phosphokinase. The fish stunned using CO2, ice asphyxia and air exposure presented coloration a* significantly higher in comparison with control group, suggesting oxidation of pigments due to stress in slaughtering. No significant differences were observed on meat water-holding capacity. After slaughtering (0h), the fish stunned using CO2 and ice asphyxia presented pH significantly higher than other treatments, with no significant differences with sampling timing and lower angles on rigor mortis within 3 hours. The results demonstrate that air exposure caused an increase on stress response and subsequent deterioration of flesh quality. The methods using CO2 or ice stunning on the tested periods were equivalents for the reduction of such negative responses, delaying the establishment of rigor mortis and leading to better parameters related to fish quality.