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

Abstract

a b s t r a c tThe aim of this paper was to evaluate the effectiveness of the quick tests Viscofrit, Testo 265 and Fricheck 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 AE 1.1% to 39.2 AE 1.0%. Testo 265 was correlated to the conventional method by the equation: y ¼ 0.89x þ 4.0 (r ¼ 0.90), with a 5% level of significance. A correlation factor of 0.9 (a ¼ 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.

Oxidative stability of crude palm oil after deep frying akara (Fried Bean Paste)

“…The equation that represented the model was TPC % (Testo 270) = -1.8229 + 0.5709*conventional method and the value found for the coefficient of correlation (r) was 0.69, explaining only 47.3% of the variation in the results of this quick test, which is considered insufficient. These results differ from those found by Dsawa et al (2012), who showed a correlation coefficient of r = 0.90 and R 2 of 80.5% from the Test 265 and the official methodology in 59 samples of palm olein and cotton oil in discarded frying oil. According to Bansal et al (2010), there are some disadvantages in the use of Testo 270, which included the presence of water, salt, minerals, long warm up time and the need of daily calibration factors that affect the polarity of a sample and can give false information on the TPC.…”

“…It has been reported that the test is imprecise and provides results that correlate poorly with total polar compounds (Dsawa et al, 2012). According that same author, the kind of oil /fat used or the type of food fried could indeed have had some influence, since the same kind of oils were dispersed and did not follow a linear pattern.…”

Quality of deep frying oils and fats used in street-fairs in Goiânia, Brazil

“…However, due to the complexity of the process, no single method can entirely measure the deterioration of oils in the frying process (PRISTOURI; BADEKA; KONTOMINAS, 2010). Some punctual diagnostics has already been performed about the oil quality and quality monitoring of oil or fat used in food service in several studies (STIER, 2004;BERTANHA et al, 2009;BANSAL et al, 2009;JUÁREZ et al, 2011;OSAWA et al, 2012;DAMY;JANIERI, 2004). They used rapid methods based in color.…”

Effect of the phytochemicals curcumin, cinnamaldehyde, thymol and carvacrol on the oxidative stability of corn and palm oils at frying temperatures

“…The amount of total polar compounds, that are formed through oxidation, thermal and hydrolytic reactions during frying, indicates the degree of deterioration in frying oil (Hampikyan et al 2011;Osawa et al 2012).…”

“…The principle of the instrument is based on the measurement of changes in dielectric constant of frying oil and directly transform the data into the percentage in weight of polar compounds (Hampikyan et al 2011;Osawa et al 2012). When frying oil decompose thermally or through oxidation processes, its dielectric constant increases (Hein et al 1998).…”