Effects of Seasonal Variations on the Fatty Acid Composition of Total Lipid, Phospholipid and Triacylglicerol in the Dorsal Muscle of Mesopotamian Catfish (Silurus triostegus Heckel, 1843 ) in Tigris River (Turkey)

Abstract

The seasonal effects on the fatty acid composition of total lipid, triacylglicerol and phospholipid in the dorsal muscle of Silurus triostegus were determined by gas chromatographic (GC) method. The total polyunsaturated fatty acids (PUFA) and monounsaturated fatty acids (MUFA) were the most important groups of total lipid and statistically ranged (P<0.05) from 33.88% to 55.85% and from 23.37% to 38.71%, respectively. The major fatty acids of total lipid in all seasons were palmitic acid (16:0) in SFA, oleic acid (18:1) in MUFA, linoleic acid (18:2) in n-6 PUFA, and docosahexanoic acid (22:6, DHA) in n- 3 PUFA. In the present study, n-3/n-6 ratios of total lipid were 2.47, 1.20, 1.03 and 1.40 in spring, summer, autumn and winter, respectively. It was determined that MUFA and PUFA were the most important groups of triacylglicerol and statistically ranged (P<0.05) from 34.09% to 47.02% and from 33.13% to 46.12%, respectively. The main fatty acids of triacylglicerol were palmitic acid in SFA, oleic acid in MUFA and linoleic acid in PUFA. PUFA was the most important group of phospholipid except summer. The total PUFA percentages of the phospholipid statistically ranged (P<0.05) from 38.12% to 65.75%. The major fatty acids identified in the phospholipid were palmitic acid in SFA, oleic acid in MUFA, arachidonic acid (20:4, AA) in n-6 PUFA and DHA in n-3 PUFA in all seasons. DHA was very high in winter (30.41%). It was shown that the fatty acid compositions in the muscle of fish were significantly influenced by seasons.