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

摘要

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 madium and chemical composition of oil absorbed by the fried product. The aim of this study was to correlate the quality of frying medium and oil extacted from potrato fritters fried under rigorously controlled laboratory conditions in liquid and partially hydrogenated rapeseed oils. Oxidation and polymerization reactions predominated during deep frying of potato fritters in both frying media, but hydrolysis occured only to a small degree. The peroxide value was not a suitable quality control indicator for monitoring the thermooxidative transformation during deep frying. The most suitable method for examining such transformation was to study the content and composition of the polar fraction. A correlation existed between the amount of polymers and oxidized triacytlycerols (TAGs) and the amount of polar fraction. Small differences existed in the content of thermooxidative transformation products in the frying medium and the oil extracted from potato fritters. By monitoring anisidine value (AnV), E~(1%) _1cm 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. Thur, the use of partially hydrogenated compared to liquid rapeseed oil in deep frying process may be preferred because at the same content of polar fraction and its components partially hydrogenated rapeseed oil contained a lesser amount of secondary oxidation products.