ARS | Publication request: Controlling the frying stability of vegetable oils with tocopherols and phytosterols

Submitted to: United States-Japan Cooperative Program in Natural Resources
Publication Type: Proceedings
Publication Acceptance Date: July 1, 2008
Publication Date: August 24, 2008
Citation: Warner, K.A., Moser, J.K. 2008. Controlling the frying stability of vegetable oils with tocopherols and phytosterols. United States-Japan Cooperative Program in Natural Resources. 00:000-000.

Technical Abstract: Polyunsaturated vegetable oils are usually oxidatively stable for salad oils; however, in high stability applications such as frying, these oils are not resistant to the deteriorative processes of oxidation, hydrolysis and polymerization. To solve this problem in the past, oils were hydrogenated and contained additives to increase fry life of the oil and shelf life of foods. Now, food manufacturers are investigating alternatives to hydrogenated oils in order to decrease/eliminate trans fatty acids. One solution includes modifying fatty acids in the oil--increasing oleic and decreasing linoleic and linolenic acids. In addition, enhancing amounts and types of inherent minor oil components such as tocopherols and phytosterols may help produce more stable frying oils. Tocopherols are well known antioxidants in vivo and in vitro. The generally accepted order of antioxidant efficacy in ambient temperature oils is delta>gamma>alpha. The amounts of the four homologues vary between oilseed types. For example, sunflower oil has approximately 95% of its total tocopherols as alpha; however, soybean oil has the highest percent of delta for most common oilseeds and is one of the best sources of gamma tocopherol. Phytosterols are the largest unsaponifiable component in vegetable oils, yet little is known about the effects of phytosterol concentration, and of individual phytosterols, on oil stability. Some phytosterols have been reported to have either antioxidant or antipolymerization activity in heated oils, but little is known about the possible mechanisms for their activity or about the effect of phytosterol concentration, and structures on oil stability.