Gc Analysis of Changes in the Fatty Acid Composition of Sunflower and Olive Oils Heated with Quercetin, Caffeic Acid, Protocatechuic Acid, and Butylated Hydroxyanisole

The objective of this study was to determine the effect on fatty acid composition of heating olive and sunflower oils with selected natural and synthetic antioxidants. The antioxidants investigated were quercetin, caffeic acid, protocatechuic acid, and butylated hydroxyanisole (BHA), each at concentrations of 0.02, 0.04, and 0.06%. Oils with no added antioxidants were also heated. After heating of the samples at 90°C for 72 h and 120 h, then preliminary saponification of the fat and esterification of the acids, the fatty acids were determined as the methyl esters by gas chromatography; heptadecanoic acid was used as internal standard. The high temperatures had a negative effect on fatty acid composition. Olive oil was more resistant than sunflower oil to changes during heating. In general, the effectiveness of natural antioxidants (quercetin, caffeic acid, and protocatechuic acid) was no less than that of the synthetic antioxidant (BHA).