Application of FTIR spectroscopy for monitoring the stabilities of selected vegetable oils during thermal oxidation

Abstract

Fourier transform infrared spectroscopy has been developed for rapid monitoring of the oxidative stabilities of selected vegetable oils, namely corn oil, rice bran oil, soybean oil, and sunflower oil during thermal treatment at 160°C for 120 h. There were several absorbance changes between non-oxidized and oxidized vegetable oils during thermal oxidation. Peak intensities at 3470, 1655, and 967 cm-1 were increased; meanwhile peak intensities at 3008 and 722 cm-1 were decreased. The R2 values for the correlation between the absorbance changes at 3008 cm-1 and the specific absorptivities of conjugated dienes for corn oil, rice bran oil, soybean oil, and sunflower oil were 0.938, 0.845, 0.978, and 0.824, respectively. The absorbance changes of Fourier transform infrared spectra at 3008 cm-1 were also correlated with the specific absorptivities of conjugated trienes and p-anisidine values with the acceptable R2 values. Compared with the conventional technique, the use of Fourier transform infrared spectroscopy for measurement the thermal oxidative stability has some advantages, i.e., it is a rapid technique and no sample preparation. In addition, Fourier transform infrared spectroscopy reduces or eliminates solvents and chemical reagents that are hazardous to human health or to the environment; therefore, Fourier transform infrared spectroscopy can support the campaign of "green analytical chemistry." © 2013 Copyright Taylor and Francis Group, LLC.