During deep-fat frying, a complex series of reactions takes place resulting in hydrolysis, oxidation and polymerization of the oil. As quality of fried foods is affected by that of the oil, regulations or guidelines have been established in many countries to guarantee high quality foods. In this lecture, present regulations mainly focusing on oil deterioration and setting limits to alteration compounds are reviewed. Among analytical methods to control oil quality, polar compound and polymer

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... rminations stand out. Studies carried out in different countries indicate the need for improving the quality of frying oil to produce more nutritious fried foods. Practical deep-fat frying can be divided in industrial and fast-food segments, characterized by the use of continuous and discontinuous fryers, respectively. From the analysis of a high number of samples it is deduced that the present situation is very different in both segments and that the main problem is to determine when the fat or oil has to be replaced where there are no laboratory facilities. Hence, simple rapid analytical tests to substitute for official methods are neccesary to monitor oil quality in restaurants and fried food outlets. Data of validity of rapid tests will be presented with particular emphasis on the utility of commercialized kits like Oxifrit-Test and Veri-Fry to improve the quality of frying fats and oils.