Major physical and chemical changes in oils and fats used for deep frying: Regulation and effects on health

Fried foods are widely consumed in Brazil and in the world. Frying is a complex process with human health risks. One of the objectives of this review was to present the main physical changes (darkening, viscosity and foam formation) and chemical changes (hydrolysis and autoxidation) that occur in oils and/or fats during the frying process. Another objective was to investigate the main factors associated with oil and/or fat degradation, namely frying temperature and time; surface/volume ratio; type of heating; addition of new oil; type and quantity of the food being fried; presence of metal contaminants; equipment used; and presence of antioxidants. Some existing frying oil or fat quality control methods (total polar compound analysis, acidity, peroxide index, p-anisidine value and rapid quantitative methods) were also presented. The review closes with the regulations concerning the frying process, effects of degraded compounds on human health, and recommendations for improving frying oil or fat quality listed in Technical Report no 11 of the National Sanitary Surveillance Agency.