Avaliação da qualidade de óleos e gorduras de descarte de fritura utilizados em estabelecimentos da cidade de Itaqui/RS

Abstract

Frying is a complex process in which the food is submerged in hot oil or fat and giving the product a characteristic of color, flavor and texture, making the sensory attributes intensified and increasing its consumption. However, when oils are used for a long time or are subjected to high temperatures, a complex series of reactions occurs, producing many degradation compounds, which modify their quality and can put consumers health at risk. The objective of the work was to evaluate the physicalchemical alterations of vegetable oils used in the frying process, after their disposal in different samples provided by commercial establishments in the city of Itaqui/RS. The analyzes applied to evaluate the quality of oils from the 10 establishments were: refractive index (40ºC), acidity index (mg/KOH.g-¹), peroxide index (mEq/Kg), conjugated trienic acids (E-¹%1cm) and instrumental color parameters. The results found for the refractive index showed an average value (1,468), being slightly above the limit range. Regarding the acidity index 100% of the samples showed values less than 0,6 mgKOH.g-¹ of oil, in accordance with established by RDC 270. As for the peroxide index, only 30% of the samples showed results less than 10 mEq.Kg-¹ A4 (7,83 ± 0,025), A6 (2,08 ± 0,097) and A8 (2,16 ± 0,145). For the percentage of conjugated trienic acids, where the highest percentage A9 (4,62%) soybean oil compared to the standard. The instrumental color parameters, evaluated the (∆E*) expressing the color difference of the samples comparing them with the standards A7 (4,32 ± 0,07) shows greater difference in color for soybean oil, and for oil cotton A8* (1,68 ± 0,08) shows greater difference in color. And for values (∆H*) it evaluates the difference in hue between the discard samples and the standards, in samples A1 and A2 (1,91 ± 0,05 and 0,07) showed greater difference in hue for soybean oil, for cotton oil (∆H *) A8* (0,98 ± 0,04) greater difference in shade. In the samples of refractive indexes there was a decrease in the number of installations and the acidity index was in agreement with what was allowed, the peroxide index 70% indicated the deterioration of compounds by oxidation, the conjugated trienoic acids obtained a higher percentage compared to the standards, color distinguished referring to pattern. The amount of compounds formed during frying is related to the composition of the oil, care in the process preserves the quality of the final product and extends the useful life of the oil, after its disposal the oil continues to undergo changes.