Comparative study of the oxidation of cold-pressed and commercial refined camellia oil during storage with 1H and 31P NMR spectroscopy.

The oxidation of cold-pressed and commercial refined camellia oil stored at room temperature for one year was comparatively studied by 1H and 31P NMR spectroscopy. The oxidation of extra virgin olive oil (EVOO) under the same conditions was further compared. The 1H NMR showed that no aldehydes were formed in the studied period. Coupled with the changes of unsaturated acyl groups, the oxidation degrees of the three oils could be obtained follow the order: commercial refined camellia oil > cold-pressed camellia oil > EVOO. The 31P NMR showed that the evolution of diacylglycerols (DGs) and ratio D in commercial refined camellia oil was fairly different from other two oils. Besides, the kinetics curves of unsaturated acyl groups and ratio D both fit to an exponential equation with high coefficients which indicated that the oxidation of the studied oils progressed in an exponential way with storage time at room temperature.