ARS | Publication request: The Effect of Phytosterol Content on Polymerization and Oxidation of Heated Oils

Submitted to: Annual Meeting and Expo of the American Oil Chemists' Society
Publication Type: Abstract Only
Publication Acceptance Date: February 21, 2007
Publication Date: May 13, 2007
Citation: Moser, J.K., Warner, K.A. 2007. The Effect of Phytosterol Content on Polymerization and Oxidation of Heated Oils. Annual Meeting and Expo of the American Oil Chemists' Society. 00:000-000.

Technical Abstract: Phytosterols occur as hundreds of different structures in nature, but beta-sitosterol, campesterol, stigmasterol, and delta5-avenasterol make up the majority of phytosterols in most vegetable oils. Some vegetable oils have higher phytosterol content than others, therefore one of the objectives of this research was to determine if phytosterol content has an effect on stability of heated oils. Mixed free phytosterols were added to soybean and high-oleic sunflower oils stripped of their endogenous tocopherols and phytosterols at levels of 0.5, 1.0 and 2.5%. These oils were heated for 8-12 hr at 180 deg C and polymer formation was followed by HPLC-SEC. Phytosterol content up to 2.5% did not have any effect on polymer formation in either of the two oils. Some phystosterols, especially those with a side-chain ethylidene group, have been found to inhibit oxidative degradation and polymerization of unsaturated fatty acids at high temperatures. However, the mechanism for this activity has not yet been clearly determined. To determine if phytosterol composition has an effect on heat stability, phytosterols were added individually to stripped soybean oil (500 and 1000 ug/g) and heated at 180 deg C. After 8 hr heating, oils that had added phytosterols with one or more double bonds had fewer polymerized triacylglycerides than the control.