Identification of Oxidation Compounds of 1-Stearoyl-2-linoleoyl-sn-glycero-3-phosphoethanolamine during Thermal Oxidation.

Heat-induced oxidative modification of phosphatidylethanolamine molecular species as potential functional food components was investigated. 1-Stearoyl-2-linoleoyl-sn-glycero-3-phosphoethanolamine (SLPE) was chosen as a model. The optimal temperature for hydroperoxide formation was determined by mass spectrometry. The maximal level of formation of this compound was obtained at 125 °C. The structures of nonvolatile organic compounds (non-VOCs) were identified using liquid chromatography-electrospray ionization mass spectrometry combined with an acid treatment. Kinetics of formation of non-VOCs was monitored over time. Results showed that the level of the SLPE precursor rapidly decreased during thermal oxidation and oxygenated products, such as hydroxyl, oxo, or epoxy groups, were formed. The VOCs formed from oxidized SLPE were determined by headspace solid-phase microextraction followed by gas chromatography-mass spectrometry analysis. The result showed that a saturated methyl ketone (2-heptanone) was the most predominant VOC of SLPE. Kinetics indicated that the formation of VOCs was related not only to the decomposition of hydroperoxides but also to the further decomposition of non-VOCs.