EVALUATION OF THE QUALITY OF FRYING OILS USED AT THE UNESP IBILCE CAFETERIA

Abstract

In this work, the frying oils used by the cafeteria located at IBILCE/UNESP in São José do Rio Preto-SP were evaluated. The goals were to determine the levels of alteration of the oils and to inform the establishment about good manufacturing practices, in order to provide higher quality food for the customers. The following methodologies were used: determination of total polar compounds, percentage of free fatty acids, Oil Test method, conjugated dienes, peroxide indices, and fatty acids profile. The limits adopted for the evaluation of the possible alterations were based on the legislation adopted by some countries: 25% for total polar compounds, 1% for the presence of free fatty acids, and 10 meq/kg for peroxide indices. The results obtained indicated that 53.2% of the 47 samples analyzed for total polar compounds were above the limit; 77.8% of the 9 samples whose contents of free fatty acids were analyzed exceeded the 1% limit; and 33.3% of the 9 samples evaluated for peroxide indices showed values higher than 10 meq/kg, exceeding the established limit. The contents of conjugated dienes varied between 0.36% and 2.43%, with an average value of 1.57%. Application of the Oil Test method showed that oil changes would be recommended for 66.7% of the samples analyzed, with the results obtained using the colorimetric scale indicating the alteration level “change”. In the evaluation of the fatty acids profiles of the oils, the polyunsaturated fatty acids were predominant, with a percentage decrease after each cycle of frying. Consequently, the saturated fatty acids and monounsaturated fatty acids increased. The results of the analytical determinations reinforce the importance of evaluation and monitoring of the changes undergone by the oil during the time interval in which the same oil is used for differing frying processes, so that the establishment can offer a higher quality of fried foods to the customer.