Frying Oil Deterioration and Vitamin Loss During Foodservice Operation

Abstract
Oxidation and vitamin E loss in four frying oils (two partially hydrogenated soybean oils, one with methyl silicone, the other with tertiary butyl hydroquinone, citric acid and dimethyl siloxane added; a semi‐solid hydrogenated soybean and palm oil shortening with mono and diglycerides added; and 100% corn oil) were studied under experimental and ‘actual’ operational conditions. Vitamin E loss in the frying oil increased significantly with increasing fatty acid oxidation. Added antioxidants, vitamin E and hydrogenation of fat decreased the rate of vitamin E loss. No significant change in vitamin E of the French fries occurred during 4 days of commercial frying; a significant increase in French fry fat uptake improved the 40% reduction in vitamin E of the frying oil. Vitamin C in the French fries (a major source of the vitamin in fast food meals) decreased significantly as the vitamin E content of the oils was reduced.