A Quick Method for Determining Total Polar Compounds of Frying Oils Using Electric Conductivity

Abstract

Oil qualities during 40 h unconsecutive frying process were analyzed by combined tradition chemical indexes and electric conductivity (EC), and the correlation between quality index of frying oil and total polar compounds (TPC) was also studied. The result shows that frying oil’s quality trends to deterioration with the extension of frying time. TPC was positively related to EC, acid value (AV), carbonyl value (CV), peroxide value (POV), and p-anisidine value (PAV) of frying oil. The correlation coefficient between TPC and other quality index decrease in the order of EC, AV, CV, POV, and PAV and were 0.9583, 0.9303, 0.9152, 0.7949, and 0.7082, respectively. EC has the highest correlation with TPC. Furthermore, repeated experiment showed that relative standard deviation ranged from 1.08 to 2.17 %, and there are no significant differences in TPC value by between traditional TPC method and EC method (P > 0.05). EC method could be a good selection to predict the TPC and discard point of frying oil.