Study of the effectiveness of quick tests based on physical properties for the evaluation of used frying oil

The aim of this paper was to evaluate the effectiveness of the quick tests Viscofrit, Testo 265 and Fri-check in the monitoring of used frying oil for discarding, as a substitute for the measurement of total polar compounds (TPC), indicating the advantages and disadvantages of each test. Fifty-nine frying oil samples used to fry different types of food were evaluated using quick tests and the TPC open-column conventional method. The samples presented TPC values from 6.0 ± 1.1% to 39.2 ± 1.0%. Testo 265 was correlated to the conventional method by the equation: y = 0.89x + 4.0 (r = 0.90), with a 5% level of significance. A correlation factor of 0.9 (α = 0.05) was essential for these results, since water in the food increases the TPC values. Viscofrit provided results consistent with the open-column method for 78.8% of the samples, with 9.3% of false positive results. Testo 265 and Viscofrit showed good results for the substitution of the TPC conventional method, respecting their limitations. Viscofrit is not recommended for high melting point samples.