engleski

Chemometric analysis of high-temperature degradation of edible vegetable oils

As registered from previous studies, oils submitted to thermal degradation undergo physical and chemical changes. Changes in infrared spectra of several vegetable oils after exposure to frying were monitored using ATR-FTIR spectroscopy and principal component analysis. Commercial samples of extra virgin olive oil, sunflower oil, rapeseed oil, hazelnut oil and palm oil were exposed to frying at the temperature of (230 ± 1) °C during the five hours. Samples of 5 ml were taken from the frying flask every 10 minutes which gave total of 32 samples for FTIR measurement and further statistical analysis. The aim of this study was to investigate the effects in vibrational spectra during the frying process and to assign possible structural changes of particular vegetable oil using the eigenvectors obtained from principal component analysis. Furthermore, from the vibrational spectra a kinetic model of oil degradation was established. In this study we recognized the most prominent changes in vibrational band at 967 cm− 1 which arise due to the formation of trans- fatty acids and in the C– H stretching area due to decrease in degree of unsaturation. These changes are not so prominent for palm oil because palm oil does not contain so much unsaturated fatty acids as other measured vegetable oils from this study. There are also changes in vibrational bands at 1163 cm− 1, 1118 cm− 1 and 1097 cm− 1 due to the formation of ketones, aldehydes and free fatty acids from esters.

Chemometrics; Vegetable Oils

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