Determination of Extra Virgin Olive Oil Adulteration Using Laser Induced Fluorometry – Chlorophyll Relative Intensity Method

Abstract A new method has been proposed for detecting the potential adulteration of extra virgin olive oil with processed sunflower oil. This method is based on analysing the laser-induced fluorescence (LIF) spectra of samples. The technique involves measuring the intensity ratio of three specific fluorescence peaks within the 650–750 nm region of the spectra, which are attributed to chlorophyll derivatives. The samples are excited with a 460 nm blue laser in an offset configuration. The results obtained indicate that the relative intensity ratio of these characteristic chlorophyll peaks is consistently correlated with the percentage of oil adulteration. A parameter named the chlorophyll relative intensity (CRI) number has been introduced, which is based on the relative intensity ratios of the chlorophyll peaks in the LIF spectra of the extra virgin olive oil sample. The CRI function demonstrates a linear relationship with the adulteration percentage up to 80%, with a high regression coefficient ( R 2 ) value of 0.9984. This method can be applied accurately when the original fluorescence spectra of unadulterated extra virgin olive oil are known, and it can provide valuable information about the source of unknown oil samples.