A comparison of the antioxidant properties of steryl ferulates with tocopherol at high temperatures

Steryl ferulates (esters of phytosterols and ferulic acid) have long been studied for their health-promoting properties, partially owing to their capacity to inhibit oxidation. The good heat-stability of rice bran oil has been attributed to its high content of steryl ferulates and tocopherols. It has been suggested that these compounds have a synergistic effect as antioxidants. In this model experiment, we determined the capacity of sitostanyl ferulate and a-tocopherol (alone or as a mixture) to prevent polymerization of high oleic sunflower oil at 100 and 180 degrees C. The formation of polymers was significantly reduced at both temperatures and by both antioxidants, as well as their mixture, though no synergistic effect was seen. Further, we followed the decrease in antioxidant levels and found that sitostanyl ferulate was degraded at a lower rate than alpha-tocopherol, indicating that sitostanyl ferulate is a promising antioxidant for high temperature applications. (c) 2006 Elsevier Ltd. All rights reserved.