Efficient Detection of Extra Virgin Olive Oil Adulteration via UV and FTIR Spectra in combination with Heat-Mediated Oxidation Method

Abstract

The main aim of this study is simple and fast authentication of extra virgin olive oil by different spectroscopic techniques individually and also in combination with minimal chemical waste. UV spectra of the EVOO and mixed olive oil samples were recorded before the heating test and then along the thermal degradation experiments at the 45- and 90-mins intervals set for the analysis.  The EVOO and mixed oils samples showed high absorption values around 240-300 nm band. The results showed that the characteristics of FTIR spectra including peak number, peak position and peak shape in mixed samples were significantly different from EVOO samples. According to the studies, the frequencies of around 2920 cm⁻¹ and 2856 cm⁻¹ could be related with C–H stretching (e.g. cis-double bonds) and with –C–H asymmetrical and symmetrical stretching in methylene groups. The frequency at 2925 cm⁻¹ is associated with aliphatic CH2 groups. Around 1366 cm⁻¹ and 1451 cm⁻¹, these frequencies could be associated with the bending vibrations of C–H groups. The results reveal that the UV–VIS and FT-IR analytical tools are the most suitable and reliable tools to detect and quantify high levels (over 10%) of adulteration in mixes of EVO with other vegetable oils.