Effect of α- and γ-tocopherols on thermal polymerization of purified high-oleic sunflower triacylglycerols

The antipolymerization effects of alpha- and gamma-tocopherols were compared in model systems composed of purified high-oleic sunflower triacylglycerols at 180 degrees C. gamma-Tocopherol was much more effective as an antipolymerization inhibitor than alpha-tocopherol, partly due to lower oxidizability/disappearance. Purified triacylglycerols of sunflower, rapeseed, and high-oleic sunflower oils were less stable than their nonpurified forms containing tocopherols. Results confirmed that tocopherols per se can act as antipolymerization agents in high-oleic oils at frying temperatures. No synergism was observed when alpha- and gamma-tocopherols were present together although larger amounts of residuals were left for both tocols. Results suggested 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).