Processing yield and chemical composition of rainbow trout (Oncorhynchus mykiss) with regard to body weight

Abstract

The influence of weight (W) category of the rainbow trout on processing yield and chemical composition of the entire eviscerated fish and fish fillet was analyzed. A completely randomized design was employed for processing variables (W₁= 300 to 370 g and W₂ = 371 to 440) coupled to a 2 x 2 factorial scheme for the chemical composition (W₁and W₂ and forms of presentation: fillet and whole eviscerated fish). W₁ showed higher yield for entire eviscerated fish (83.00%) and head (13.27%), but a lower yield for the viscera (17.00%), when compared to W₂. We did not affect abdominal muscle yield, fillet with or without skin, skin percentage and residues. There were significant differences between W for moisture (W₁= 72.30% and W₂= 71.15%) and lipids (CP₁= 7.96% and CP₂= 9.04%) rates. Fillet moisture contents (73.74%) and crude protein (19.05%) were higher (p < 0.01) than for entire eviscerated fish (69.71% and 17.81%, respectively). Ash (2.15%) and lipid (10.48%) rates were higher (p < 0.01) for entire fish when compared to those of fillets (1.16% and 6.52%, respectively). The slaughter of fish weighing between 300 and 370 g and their fillets are more adequate for the market.