FATTY-ACID COMPOSITION OF SALMONID MUSCLE CHANGES IN RESPONSE TO A HIGH OLEIC-ACID DIET

Substitution of high oleic acid sunflower oil for herring oil in formulated salmonid diets affected the fatty acid composition of muscle, liver and visceral fat from coho salmon (Oncorhynchus kisutch) and rainbow trout (O. mykiss). Fish were fed diets containing either high oleic acid sunflower oil or herring oil as the supplemental lipid source (12.4 g/100 g diet) for 1-2 mo. Muscle from fish fed the sunflower oil diet had twice the concentration of oleic acid (similar to 25 9/100 g lipid) as muscle from fish fed the herring oil diet (similar to 12 g/100 g lipid). The maximum concentration of oleic acid in the muscle was obtained after only 2 wk of feeding the sunflower oil diet. Oleic acid concentrations in liver and visceral fat of fish fed the sunflower oil diet were significantly higher than in fish fed the herring oil diet. Rainbow trout fed the sunflower oil diet for 4 wk maintained the higher oleic acid concentrations in muscle and liver when deprived of feed for 2 wk compared with fish fed the herring oil diet. These data indicated that accumulation of oleic acid in coho salmon and rainbow trout muscle was fairly rapidly achieved when a high oleic acid diet was fed. The differences between the fish receiving the two dietary treatments in fatty acid composition and in concentrations of thiobarbituric acid-reactive substances in muscle stored at refrigerated temperatures were consistent with previously reported differences in aroma perceived by a sensory panel.