Effect of alpha- and gamma-tocopherols on thermal polymerization of purified high-oleic sunflower triacylglycerols

The antipolymerization effects of alpha- and gamma-tocopherols were compare d in model systems composed of purified high-oleic sunflower triacylglycero ls at 180 degrees C. gamma-Tocopherol was much more effective as an antipol ymerization inhibitor than alpha-tocopherol, partly due to lower oxidizabil ity/disappearance. Purified triacylglycerols of sunflower, rapeseed, and hi gh-oleic sunflower oils were less stable than their nonpurified forms conta ining tocopherols. Results confirmed that tocopherols per se can act as ant ipolymerization agents in high-oleic oils at frying temperatures. No synerg ism was observed when alpha- and gamma-tocopherols were present together al though larger amounts of residuals were left for both tocols. Results sugge sted that high-oleic/high gamma-tocopherol oils (such as high-oleic canola and high-oleic soybean oils) may provide better frying oils than high-oleic /high-alpha-tocopherol oils (such as high-oleic sunflower oil).