Correlation of quality of frying oil and oil extracted from potato fritters fried in liquid and partially hydrogenated rapeseed oils

The increase in consumption of food fried in the so-called 'deep-frying-oil ' entails the necessity of knowledge of both thermooxidative transformation occuring in the frying medium and chemical composition of oil absorbed by the fried product. The aim of this study was to correlate the quality of fr ying medium and oil extracted from potato fritters fried under rigorously c ontrolled laboratory conditions in liquid and partially hydrogenated rapese ed oils. Oxidation and polymerization reactions predominated during deep fr ying of potato fritters in both frying media, but hydrolysis occured only t o a small degree. The peroxide value was not a suitable quality control ind icator for monitoring the thermooxidative transformation during deep frying . The most suitable method for examining such transformations was to study the content and composition of the polar fraction. A correlation existed be tween the amount of polymers and oxidized triacylglycerols (TAGs) and the a mount of polar fraction. Small differences existed in the content of thermo oxidative transformation products in the frying medium and the oil extracte d from potato fritters. By monitoring anisidine value (AnV), E-1cm(1%) and the content and composition of the polar fraction in the frying medium, it was possible to evaluate the quality of the fat in the fritters. Thus, the use of partially hydrogenated compared to liquid rapeseed oil in deep fryin g process may be preferred because at the same content of polar fraction an d its components partially hydrogenated rapeseed oil contained a lesser amo unt of secondary oxidation products.