Carcass, fillet and byproducts yield of filleting of Nile tilapia <em>Oreochromis niloticus</em> (L.) in relation to body weight

Abstract

The experiment was undertaken at the fish processing industry Frigopeixe in Toledo, state of Paraná, Brazil. Its aim was to analyze carcass, fillet and other byproducts yields (ventral abdominal muscles yield, percentage of skin and residues) of the Nile tilapia, Oreochromis niloticus (Perciformes, Cichlidae) for two live weight categories. Residues consisted of head, viscera and fin percentages. One hundred specimens were fed with pellet rations with 22% of crude protein during 5 months. Fish were placed in tanks for 24 hours before put down, underwent thermal shock, eviscerated and filleted. Filleting process was done in series by more than one person using industry methodology. Completely randomized design with two treatments (weight categories W₁=300-400 g e W₂=401-500 g), with 50 replications. Each fish was considered an experimental unit. The W₂ category produced high yield in carcass without head (78.18%), ventral abdominal muscles (3.51%) and crude skin (6.56%). The W₁ was significantly higher for head (14.29%) and viscera (10.09%) percentages. There was no significant difference for fillet yields (W₁=36.50% and W₂=36.84%) and fin percentages (W₁=8.14% and W₂=8.00%), between the two weight categories of Nile tilapia.