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

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 ۴۵- and ۹۰-mins intervals set for the analysis.  The EVOO and mixed oils samples showed high absorption values around ۲۴۰-۳۰۰ 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 ۲۹۲۰ cm−۱ and ۲۸۵۶ cm−۱ 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 ۲۹۲۵ cm−۱ is associated with aliphatic CH۲ groups. Around ۱۳۶۶ cm−۱ and ۱۴۵۱ cm−۱, 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 ۱۰%) of adulteration in mixes of EVO with other vegetable oils.

Keywords:

Olive oil , Adulteration , FT-IR spectroscopy , UV-vis spectroscopy , Heat-Mediated Oxidation Method