Elucidation of decomposition pathways of linoleic acid hydroperoxide isomers by GC-MS and LC-MS/MS.

Food lipid oxidation provides various volatile compounds involved in food flavor via the decomposition of lipid hydroperoxide (LOOH). This study predicted the pathways which can coherently explain LOOH decomposition focusing on hydroperoxy octadecadienoic acid (HpODE) isomers (9-EZ-HpODE, 9-EE-HpODE, 10-HpODE, 12-HpODE, 13-ZE-HpODE, and 13-EE-HpODE) which are the major LOOH contained in edible oils. Each standard was first prepared and thermally decomposed. Generated volatile and non-volatile compounds were analyzed by GC-MS and LC-MS/MS. The results showed that all HpODE decomposition was based on the factors such as favorable scission, radical delocalization, and cyclization. Interestingly, the formation of 8-HpODE and 14-HpODE were demonstrated during HpODE decomposition. The insights obtained in this study would explain the generation pathways of flavor involved in food quality.