Formation of hydroperoxy- and hydroxyalkenals during thermal oxidative degradation of sesame oil monitored by proton NMR

The usefulness of H-1 nuclear magnetic resonance (NMR) for studying oil oxidation processes was tested. Refined sesame oil was submitted to oxidative conditions at 70 degreesC with circulating air, and the status of the sample was studied daily by H-1 NMR. This technique permits the determination of the proportions of the acyl groups in the oil throughout the oxidation process and, at the same time, allows monitoring of the formation and degradation of primary oxidation compounds, as well as of the formation of secondary oxidation products. Generation of the geno- and cyto-toxic oxygenated aldehydes 4-hydroxy-, 4-hydroperoxy- and 4,5-epoxy-trans-2-alkenal was proved.