Spectroscopic and chemometric analysis and oil stability index characterization of thermo-oxidized edible vegetable oils

Abstract

Edible vegetable oils are sources of polyunsaturated fatty acids, necessary for a balanced diet capable of providing elements that act on the energetic, structural, and hormonal composition of humans. The growing consumption of these foods has encouraged the search for techniques capable of characterizing their compositions and transformations when subjected to industrial processes or during domestic use. We propose to analyze the transformations undergone by edible vegetable oils originating from different plants due to thermal oxidation. For this, dynamic viscosity, oxidative stability index, fatty acid profile, and infrared spectra determined before and after being subjected to thermal oxidation. The results from infrared spectroscopy were improved through Principal Component Analysis (PCA). Among other results, it was possible to establish correlations between the FTIR spectra, dynamic viscosity, and the profile of fatty acids, allowing the prediction of the concentration of polyunsaturated fatty acids (PUFA) after thermal oxidation by measuring the spectrum of samples before the thermal oxidation process. Furthermore, it is observed that the dynamic viscosity is strongly altered by thermal oxidation, which is directly related to the decrease in PUFA content. The results obtained can be used to predict quality factors of edible vegetable oils, helping to choose the right type of oil for each industrial or domestic process.

Practical Applications: This research holds significant practical implications, particularly in detecting adulteration and fraud of edible vegetable oils. The developed method uses physicochemical properties and infrared spectroscopy with principal component analysis to characterize oils and to determine the oil stability index.