Densidades de transporte associadas a tempos de repouso pós-transporte para tilápia-do-nilo em peso de abate

Abstract

The transport of live fish for slaughter is stressful due to factors such as crowding, increased ammonia nitrogen, temperature fluctuations, and vehicle vibration. A resting period after transport can help mitigate stress and ensure fillet quality. Thus, the study of practices commonly used by the tilapia processing industry, such as transport densities and rest times before slaughter, is important to understand their impacts on processing and fillet quality. This study evaluated the impacts of transport at medium (250 kg/m³) and high (500 kg/m³) densities with different post transport resting times (0, 2, 4, 6 hours) on Nile tilapia fillets, aiming to define a protocol that promotes a return to initial homeostasis and benefits tilapia meat quality. The experiment was conducted in a 2 x 4 factorial design, with 15 repetitions per treatment. The results indicated that the longest pre-rigor mortis time was observed at 500 kg/m³ with 4 hours of rest. The density of 250 kg/m³ with 4 hours of rest produced fillets with higher red and yellow intensities. The greatest cooking weight loss occurred at 500 kg/m³ without rest. Fish fillets with 4 and 6 hours of rest showed greater firmness, lower brightness, and better water retention. Six hours of rest restored glycogen, glucose, and lactate levels, increased pH, and reduced red and yellow intensity. The activity of catalase and glutathione S-transferase enzymes increased at a density of 250 kg/m³ with 6 hours of rest. However, no significant effects were observed between treatments for the activity of superoxide dismutase, lipid peroxidation, and protein carbonylation. A six-hour post-transport rest period for tilapia, regardless of transport density, is effective in re-establishing animal homeostasis. The use of high transport density (500 kg/m³) promotes metabolic damage that affects the quality of Nile tilapia fillets.