Lipids and fatty acids of five freshwater food fishes of India

Five species of carp important in the diet of many of the people of India were examined for principal lipids and in particular for the highly unsaturated fatty acids with potential biomedical benefits. Muscle lipid was about 1% in four species but 2.5% in muscle of Labio bata. The livers however had lipid contents in the 5-10% range. The principle lipid classes were separated and the fatty acids were determined by open-tubular (capillary) gas-liquid chromatography; forty-seven fatty acids were quantified. Saturated fatty, acids were approximately 40-50% of total fatty acids in muscle lipids and monoethylenic fatty acids were 24-39%. Functionally important fatty acids of triacylglycerols in the muscle of all species included about 5% each of 18.-2n-6 and 18.-3n-3. The longer chain lengths 20:4n-6, 20:5n-3, and especially 22:6n-3, were found mostly in the polar lipids (phospholipids), although some had been hydrolyzed yielding free fatty acids with similar fatty acid profiles. Because of the low total lipid the polar lipids of the muscle were thus typically more important dietary sources of these functional fatty acids than the triacylglycerols. Among other potentially interesting polyunsaturated acids, 20:4n-6 was usually in the 5-10% range, 18:3n-6 was usually <1%, but 18:4n-3, easily converted in vivo to 20:5n-3, was common at around 1% and exceeded 2% in Labio bata muscle triacylglycerols.