Determination of oxidative stability of different vegetable oils by means of middle infrared spectroscopy and DFT calculations

Oxidative stability is one of the most important quality parameters of vegetable oils. This study aims to determine oxidative stability of five different vegetable oils by means of infrared spectroscopy combined with DFT calculations and to compare experimental and theoretical results. The oxidation induction times of hazelnut, corn, canola, safflower and sunflower oils were determined by the Rancimat method and fatty acid profile of the oils was analyzed by gas chromatography. Moreover, the middle infrared spectra of the samples was obtained by using Fourier transform infrared spectroscopy. The oxidative stability of the vegetable oils was analyzed by considering two mechanisms regarding to oxidation process in the theoretical parts of the study. The chemical hardness of fatty acids, a key characteristic of Conceptual Density Functional Theory, was calculated and discussed. It was evaluated that there was a remarkable correlation between oxidative stability and chemical hardness of fatty acids. The harder fatty acids had stronger oxidative stability. A new, accurate, cost-effective, and ecologically friendly technique was developed for determination of oxidative stability of vegetable oils.