Front-face and right-angle fluorescence spectroscopy for monitoring extra virgin olive oil spectrum evolution

Abstract

Fluorescence spectroscopic techniques were applied in a study in order to monitor the evolution of the spectral pattern of extra virgin olive oil (EVOO) samples exposed to indirect light at room temperature. Detailed information was extracted from three-dimensional front-face (FF) fluorescence spectra with excitation wavelengths ranging from 230 to 646 nm and emission wavelengths ranging from 250 to 698.5 nm. Relevant emission regions were revealed in FF experiments that were useful to study the variability of the characteristic spectral patterns and to develop fast inspection procedures. Such procedures include simultaneous excitation at wavelengths lower than 400 nm, which was proposed and implemented in a rightangle prototype in order to monitor the evolution of EVOO samples exposed to indirect light. Emission signals at local maxima around 400, 434, 464, 513 and 674 nm were found to be relevant. Ongoing research highlights that hyperspectral images provide spectral patterns of the olives, allowing more precise sorting into categories, which would enable the classification into lots of oils with more homogeneous characteristics for subsequent modelling.