Effect of synthetic antioxidants on cholesterol stability during the thermal-induced oxidation of a polyunsaturated vegetable oil

As a molecule with an unsaturated bond, cholesterol is prone to oxidation. Cholesterol oxidation products (COP) are found in many common foods and have been shown to be atherogenic, cytotoxic, mutagenic, and possibly carcinogenic. Efforts to reduce the formation of oxidation products are considered important during the manufacture and processing of foods. The effect of synthetic antioxidants on cholesterol oxidation has not been extensively studied. We assayed the effect of five commonly used antioxidants-BHT, BHA, the n-propyl ester of 3,4,5-trihydroxy benzoic acid (PG), TBHQ, and 6-ethoxy-1,2-dihydro-2,4-trimethylquinoline (EQ)-on cholesterol stability when oxidation is induced in a Rancimat 679 instrument by bubbling air through the sample at 150degreesC. The sample consisted of 200 mg cholesterol dispersed in 100 g of a polyunsaturated vegetable oil (soybean oil). Formation of six COP was measured at the induction period, and at the 50 and 100 muS conductivity values. Under the experimental conditions, BHT and TBHQ were the most effective inhibitors of cholesterol oxidation. BHA and EQ were less effective, and PC was unable to prevent cholesterol oxidation. Synthetic antioxidants were more effective in preventing COP formation at the nucleus of the cholesterol structure than at the lateral chain.