Positional distribution of fatty acids on triacylglycerols of menhaden (Brevoortia tyrannis) and salmon (Salmo salar) oils

Pure triacylglycerols of both menhaden and salmon oils were separated on Florisil columns. The triacylglycerols were subjected to positional distribution analysis using a modified procedure involving reductive cleavage with a Grignard reagent. Cleaved fractions were separated on thin layer chromatography (TLC) plates using hexane-diethyl ether-formic acid (80:20:1, v/v/v) as the mobile phase. Separated fractions were derivatized and analyzed by gas chromatographic method to determine the component fatty acids. Results showed that salmon oil contained a greater percentage of PUFA at the Sn-2 position of the triacylglycerol as compared to menhaden oil. The PUFA of menhaden oil were randomly distributed in the triacylglycerol. In salmon oil, a greater percentage of 18:3 (n-3), 20:4 (n-3), 20:5 (n-3), 22:5 (n-3), and 22.6 (n-3) was in the Sn-2 position as compared to menhaden oil. However, a greater percentage of 16:4 (n-1), 20:4 (n-6) and 18:4 (n-3) was located in the Sn-2 position of menhaden oil compared to salmon oil.