Deep-frying is chosen for being a rapid food preparation process and for attributing to the fried products unique characteristics of flavor. At the frying temperature oil interacts with air, water and components of the food which is being fried, producing compounds that are responsible for off-flavor development and deterioration in abused oils. The objective of this work was to determine the development of deterioration in fat and oils used in frying process in restaurants, bars and snack bars of São José do Rio Preto-SP. The analytical methods used to evaluate the alterations in 60 oil samples included determining the total polar compounds in frying oils (%), free fatty acids (%, expressed in terms of oleic acid) and value peroxide (meq/kg). The established limits for alteration in frying fats were 25% for polar compounds, 1% for free fatty acids and 15 meq/kg for value peroxide. According to the results obtained, it could be observed that, from the 60 analyzed samples, 30% showed higher values of polar compounds than the established limit for discarding frying oil and fat. For the free fatty acids and value peroxide, 18.3% and 8.3% of the samples respectively, showed higher values than the established limit for discarding. The high levels of total polar compounds found (57.4%) in a significant number of samples proved the necessity of making the quality of frying fat and oil better in this field of food.
frying oils; restaurants; snack bars; polar compounds; free fatty acids; peroxide value
