Effects of natural and synthetic antioxidants on the oxidative stability of borage and evening primrose triacylglycerols

The effects of natural and synthetic antioxidants on the oxidative stability of borage and evening primrose triacylglycerols (TAG), under Schaal oven conditions at 60 °C were evaluated. Conjugated dienes (CD) and 2-thiobrabituric acid-reactive substances were used as indicators for evaluation of primary and secondary lipid oxidation products, respectively. Results suggest that tocopherols are more effective antioxidants at 500 ppm than at 200 ppm. The most effective natural antioxidant was Tenox GT-2 (the formulation in oil was composed of 7.88 ppm of α-, 39.7 ppm of γ- and 21.8 ppm of δ-tocopherol) followed by δ- and α-tocopherols, while, among synthetic antioxidants, tert-butylhyroquinone (TBHQ) was more effective than butylated hydroxytoluene (BHA) and butylated hydroxyanisole (BHT) and served as the strongest antioxidant in borage and evening primrose oil TAG.