Analysis of hydroperoxides, aldehydes and epoxides by 1H nuclear magnetic resonance in sunflower oil oxidized at 70 and 100 degrees C.

A global study of sunflower oil oxidation at two different temperatures (100 and 70 degrees C) with aeration was carried out by (1)H nuclear magnetic resonance ((1)H NMR), paying attention not only to the degradation of the main components but also to the formation of others. The functional groups of compounds monitored simultaneously during the oxidation were, in addition to acyl groups, the following: hydroperoxides, conjugated dienic systems of hydroperoxy acyl groups, aldehydes including the genotoxic and cytotoxic oxygenated alpha,beta-unsaturated aldehydes, and mono- and diepoxides. Chemical shifts of protons of all mentioned groups were given. Differences between both oxidation processes were found from the initial stages to the end. The formation of diepoxides in the oxidation process of edible oils was shown for the first time, as was the influence of temperature on the formation of epoxy acyl groups, some of these latter related to leukotoxin and isoleukotoxin.