Submitted to: Journal of the American Oil Chemists' Society
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: August 3, 2009
Publication Date: August 22, 2009
Citation: Warner, K.A., Moser, J.K. 2009. Frying Stability of Purified Mid-Oleic Sunflower Oil Triacylglycerols with Added Pure Tocopherols and Tocopherol Mixtures. Journal of the American Oil Chemists' Society. 86:1199-1207. Interpretive Summary: In this research, we found that an antioxidant mixture of three major tocopherols (alpha, gamma, and delta) significantly improved the shelf life of fried food. The antioxidant effect was better when all three tocopherols were part of the mixture compared to any of the three tocopherols added separately. Frying operators are looking for alternatives for trans fat-containing hydrogenated oils for frying in the U.S. Most oils that we buy in the grocery store are excellent for salads and home use cooking, but they break down rapidly under the conditions used for frying in restaurants or by fried food manufacturers. Therefore, methods are needed to help improve oils so they do not deteriorate in quality during commercial frying. We found that the a mixture of the three tocopherols, which contribute to vitamin E activity in the body, improved the frying life of oil when compared to the same oil without tocopherols or when only one of the three tocopherols were added to the oil at a time. The antioxidant mixture also extended the shelf life of tortilla chips fried in the oil in comparison to chips fried in oil without the tocopherols. The antioxidant mixture can help to improve the quality of oil used for commercial frying and provide better tasting, more healthful fried food for the consumer.
Technical Abstract: To determine the effects of the addition of pure tocopherols to triacylglycerols, alpha, gamma, and delta tocopherols were added singly and in various combinations to stripped mid-oleic sunflower oil (SMOSUN). Tortilla chips were fried in the treated oils and then aged at ambient temperature to determine storage stability of the fried food. Frying oils were evaluated for total polar compounds (TPC) as an indicator of oil deterioration and they were also analyzed for retention of tocopherols. To determine effects of tocopherols on fried food stability, chips were evaluated for hexanal as an indicator of oxidative stability and for odor characteristics by a trained, experienced analytical sensory panel. Oil extracted from the tortilla chips was also analyzed for residual tocopherols. TPC were highest in the SMOSUN control with no additives followed by the SMOSUN containing only alpha-tocopherol. The SMOSUN oil containing gamma-tocopherol had the best fry life as indicated by the lowest TPC. Hexanal content and rancid odor intensity were highest in the SMOSUN control and in the SMOSUN containing only alpha-tocopherol. The most stable tortilla chips were fried in SMOSUN containing all three (alpha, gamma, and delta) tocopherols; however, the lowest hexanal levels were measured when gamma and delta tocopherols were at their highest amounts.