Maintaining the quality of extra virgin olive oils (EVOOs) in the current globalised market is a key challenge for the olive oil manufacturers. To maintain the quality, one major factor is to resist its oxidation during processing and storage. Resisting the oxidation in EVOOs is a challenging task requiring control of different physical and chemical factors. However, rapid, real-time, and non-destructive monitoring the oxidation in EVOOs could support in maintaining its quality during storage. The present study utilises a novel right-angle fluorescence spectroscopy-based prototype for rapid monitoring of oxidation changes in three different EVOOs varieties (Arbequina, Picual, and Cornicabra) during storage. Furthermore, the effects of light exposure on oxidation of EVOOs were also studied. Two major changes in the fluorescence spectra of EVOO samples were mainly observed: a decrease in fluorescence emission intensity at 671 nm, and an increase in fluorescence intensities at 420, 440, 464, and 515 nm. These two changes were related to a decrease in chlorophyll content and parallel formation of oxidation products. The formation of oxidation products was found to have a linear relationship with the decrease in chlorophyll content. Out of the three, the Cornicabra variety showed the highest rate of oxidation changes. Furthermore, the EVOOs degraded rapidly when get exposed to light. In a fast and non-destructive manner, the fluorescence spectroscopy-based prototype successfully monitored the oxidation changes in the EVOOs. Keywords Extra virgin olive oil • Oxidation • Storage • Light exposure Abbreviations C0 2) Singlet oxygen (3 0 2) Triplet oxygen EU European Union EVOOs Extra virgin olive oils nm Nanometre UV-Vis Ultraviolet and visible VOOs Virgin olive oils Compliance with ethical standards Conflict of interest The authors declare no conflict of interest. Compliance with ethics requirements This article does not contain any studies with human and animal subjects.

No 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.