Submitted to: Journal of the American Oil Chemists' Society
Publication Type: Peer reviewed journal
Publication Acceptance Date: 8/29/2002
Publication Date: 8/29/2002
Citation: J. Am. Oil Chemists' Soc. 79:1201-1206, 2002 Interpretive Summary: All vegetable oils contain trace levels of antioxidants (mainly vitamin E and carotenoids such as beta carotene) and these contribute to the stability of the oil and to its health-promoting properties. All vegetable oils also contain phytosterols, and although most research on phytosterols has focused on their cholesterol-lowering properties, some types of phytosterols also possess antioxidant properties. The present study was conducted to evaluate the antioxidant activity of several phytosterols and two phytosterol-rich vegetable oils (corn fiber oil and rice bran oil). Antioxidant activity can be measured in many different ways and for this study two common methods were used: instrumental measurement of Oxidative Stability Index (OSI) and antioxidant-induced antipolymerization. The results indicate that using these two criteria, rice bran oil has very good antioxidant and antipolymerization activities.
Technical Abstract: The antioxidant activity of phytosterols, oryzanol, ferulic acid ester of sterols, corn fiber oil, and rice bran oil was investigated. Commercial soybean oil and distilled soybean oil fatty acid methyl esters were both used as substrate for oxidative stability determination and viscosity analysis after the oil was oxidized. At low concentration, these materials did not improve the oxidative stability of the oil substrates, although the viscosity tended to be reduced slightly. The antipolymerization activity of steryl ferulate was increased at higher concentration more than that at lower concentration, and it was more effective than oryzanol. Rice bran oil showed very good antioxidant and antipolymerization activities.