Effects of altered ration levels on sensory characteristics, lipid content and fatty acid composition of rainbow trout (Oncorhynchus mykiss)

This study describes the effects of altered ration levels on sensory characteristics, lipid content and fatty acid composition of rainbow trout fillet. Ration levels were altered from adequate to restricted level after 0.2 and 1.0 years from hatching and from strongly restricted and restricted levels to adequate level 1.0 years from hatching. A selected and trained panel carried out descriptive sensory tests on fish fillet cross-sections. The intensity of total odour increased, and that of juiciness decreased with age, independent of ration level. Ration level had an overall effect on the total taste intensity, independent of age. Fresh odour correlated negatively to the saturated fatty acids 14:0 (r=-0.834; p<0.001), 16:0 (r=-0.831; p<0.001) and 18:0 (r=-0.668; p<0.05). Trout that had their ration level altered from restricted to adequate level 1.0 years after hatching had a higher lipid content than trout having their ration level altered from adequate to restricted level after 0.2 and 1.0 years, respectively. Including fillet lipid content in the statistical model indicated that lipid is an important factor decisive for total taste and flesh texture of the trout. Fish having their ration level altered from adequate to restricted level after 0.2 years had a significantly lower condition factor than fish having it altered 1.0 years after hatching.