Sitosterol as an antioxidant in frying oils.

The antioxidative effect of sitosterol at 1, 2 and 5% levels, in triolein, refined canola, high oleic sunflower and flaxseed oils, continuously heated for a period of up to 72 h at frying temperature of 180 °C, was studied. High Pressure Size Exclusion Chromatography (HPSEC) was used to monitor changes in peak areas of triacylglycerol (TG) polymer, monomer and ester hydrolysis products. The presence of enhanced levels of sitosterol was found to significantly decrease TG polymer formation in triolein and the vegetable oil samples after heating at 180 °C for a period of 72 h. A corresponding increase in the level of intact TG monomer and the extent of TG ester hydrolysis was observed in all samples with enhanced levels of sitosterol. Conversion of sterol to steradiene, by the 1, 2 elimination of water, may be responsible for the antioxidative effect of sitosterol at frying temperatures.