Submitted to: World Aquaculture Magazine
Publication Type: Peer reviewed journal
Publication Acceptance Date: 10/1/2003
Publication Date: 12/1/2003
Citation: Chaiyapechara, S.K.K. Liu, F.T. Barrows, R.W. Hardy, F.M. Dong. 2003. Proximate Composition, Lipid Oxidation and Sensory Characteristics of Fillets from Rainbow Trout Onchorynchus mykiss Fed Diets Containing 10% to 30% Lipid. World Aquaculture. 34(3):266-277. Interpretive Summary: We evaluated the effect of feeding high energy feeds to rainbow trout. The high fat feeds can promote greater weight gains and improved feed conversion rates, but the effect of these feeds on the fillet quality was undocumented. Feeds containing 10, 15, 20, 25 and 30% fat were fed for 24 weeks. Greater weight gains were observed for the fish fed the 30% fat diet than the fish fed the other diets. The fish fed the 30% lipid diet had higher fat content in the fillet, and the fillets has a “fishier” aroma than the fillets from fish fed the 15% lipid diet, but otherwise there were no negative effects of feeding the higher fat diets.
Technical Abstract: This study was conducted to determine the effects of increasing dietary lipid concentrations on fillet characteristics of post-juvenile rainbow trout. A feeding trial was conducted with fish meal based diets containing 10, 15, 20, 25, or 30% lipid for 24 wk. Menhaden oil was the lipid ingredient. Weight gain was significantly greater in fish fed the 30% lipid diet than in fish fed either 10%, 15%, or 20% lipid diets. There were no significant differences in visceral somatic index. Fillet lipid concentration of fish fed the 30% lipid diet (9.2-g lipid/100-g fillet) was significantly higher (P< 0.05) than fish fed either the 10% or 15% lipid diets (5.8- and 6.9-g lipid/100g fillet, respectively). In samples stored for 3 d at 5 C or 8 wk at -20 C, sensory panelists reported that the cooked fillets from fish fed the 30% lipid diet were “more fishy” than fish fed the 15% lipid diet, and preferred the cooked fillets from the 15% lipid treatment over the 30% lipid treatment. Triangle tests and fillet colorimetry showed no significant differences between fillets from fish fed the 15% and 30% lipid diets at any sampling time point. No significant differences in fillet concentrations of thiobarbituric reactive substances were observed among dietary treatments stored at either 5 C or -20 C. These results suggest that two main effects of feeding a 30% lipid diet (with fish oil as the lipid source) are higher lipid concentration in the fillet and a “fishier” aroma compared to fillets from fish fed a 15% lipid diet.