Composition, Properties and Sensory Quality of Rainbow Trout Affected by Feed Formulations

Rainbow trout were fed a fish meal-based diet or diets where 25, 50, 75, or 100% of the fish meal protein was replaced with a mixture of rendered animal protein ingredients. Diets were formulated to be iso-nitrogenous (36% crude protein) and meet all known nutrient requirements of rainbow trout. The effect of five diets on dressing percentage, chemical composition, functional properties, and sensory characteristics of rainbow trout fillets stored up to 1 wk on ice in a refrigerated room (4 C) was determined. Dressing percentage based on body weight (from 724 to 811 g) did not show a significant difference due to the diet. Raw tissue pH, 24 and 144 h post mortem, were significantly lower than the control when 75 and 100% fish meal replacement were utilized. Assessment of color, texture, flavor, and tenderness indicated that fillet were lighter, less firm, more bland, and more tender after 144 h compared to 24-h storage time. Fillets from fish fed all diets were considered as acceptable by the panel.