Fluoresence Spectra From Vegetable Oils Using Violet And Blue Ld/Led Exitation And An Optical Fiber Spectrometer

Abstract

In this article the possibility to detect adulteration of costly olive oils with cheaper vegetable oils using fluorescence spectroscopy is studied. Total luminescence spectra were recorded by measuring the emission spectra in the range 350 nm to 720 nm for excitation wavelengths from 375 nm to 450 nm. Fluorescence spectra of 12 types of olive oil samples were studied. Ten of the olive oil types were purchased locally, while two (samples 1 and 4) were obtained directly from Greek olive oil producers. Analysis of the fatty acid and the tocopherol contents has been performed. Two of the samples exhibit the content of sunflower oils, two are admixtures of sunflower and olive oils, while the remaining eight samples are natural olive oils. The samples show differences in their fluorescence spectra. The latter fact shows that fluorescence spectroscopy can be used for the quick identification of possible adulterations of olive oil, although a more detailed gas chromatographic analysis is needed for the exact quantitative determination of the content of the adulterant.