Abstract

The objective of this work was to know the deterioration of fats employed in deep frying of «french fries» potatoes at restaurant and food shop sector in Santiago (Chile), before the recent Chilean legislation became official. 96 % of the samples corresponded to polyunsaturated vegetable oils, 76 % had more than 2 % linolenic acid and 23 % of total samples contained more than 25 % of polar compounds. To predict the percentage of polar compounds, equations were developed: for soybean oil and mix soybean oil-canola the equation included viscosity or conjugated dienoic acids, while for sunflower oil viscosity and free fatty acids were considered. Sunflower oil, presented a different pattern of the altered groups that comprise the fraction of polar compounds, as compared with soybean and mix soybean-canola oils, these latter two showing significantly higher thermoxidative degradation. Among the diagnostic tests assayed, Oxifrit is recommended as a quick test for practical deterioration control.