Effect of linoleic acid position in triacylglycerols on their oxidative stability

Abstract

Four synthetically produced triacylglycerols containing linoleic and palmitic acid in different known positions were used to determine the effect of fatty acid position on their relative rates of autoxidation. The triacylglycerols were sn-1,3-dipalmitoyl-sn-2-linoleoyl (PLP); sn-1,2(2,3)-dipalmitoyl-sn-1(3)-monolinoleoyl (PPL); sn 2-palmitoyl-sn-1,3-dilinoleoyl (LPL); and sn 1 (3)-palmitoyl-sn-1,2(2,3)-dilinoleoyl (PLL) glycerols. Oxidation was evaluated both by peroxide value, and reversed phase HPLC with ultraviolet absorbance detection at 235 nm for conjugated diene of triacylglycerols oxidized linoleic acid. Triacylglycerols were oxidized at 60 °C in the dark. PLL had lower oxidative stability than LPL. This effect may be due to easier interactions between adjacent linoleic acid of PLL compared to nonadjacent linoleic acid of LPL during autoxidation. PLP had lower oxidative stability than PPL. Reversed phase HPLC analysis showed that at a low oxidation level, PLP and PPL produced monohydroperoxide and LPL and PLL produced both mono- and bishydroperoxides. These results are further evidence that fatty acid position on triacylglycerols plays a role in lipid oxidation.