Investigation on lipid profile of peanut oil and changes during roasting by lipidomic approach

Peanut oil contains large amount of non-polar lipids and minor polar lipids. However, the effect of roasting on lipid profile of peanut oil has not been investigated systematically. Herein, an UPLC-Q-Exactive Orbitrap mass spectrometry-based lipidomic method was applied to comprehensively analyze lipid profile of the oils from raw, light and dark roasted peanut kernels. Microstructure of peanut kernels, physicochemical properties and oxidized fatty acids in peanut oil during roasting were also evaluated. Dark roasting destructed the cell membrane severely according to microstructure observation. The color of the oils became darken after light and dark roasting. Acid value increased during roasting. Peroxide value, conjugated dienens, and oxidized fatty acids increased after light roasting while decreased after dark roasting. Roasting had an obvious effect on phospholipids. Triglycerides and diglycerides showed a thermal stability during this process. Our study could provide useful information for peanut oil processing.