Chaotic parameters from fluorescence spectra to resolve fraudulent mixtures of fresh and expired protected designation of origin extra virgin olive oils

Abstract

One of the most profitable products from the Mediterranean basin is extra virgin olive oil (EVOO), and, therefore, some of them have protected designation of origin (PDO) labels. In order to prevent fraudulent practices, a method to quantify adulterants has been developed. 459 binary blends composed of PDO EVOO in date (Saqura, Oleoestepa, and Duque de Baena) mixed with expired PDO EVOO (Quinta do Vallouto, Señorío de Segura, and Planeta) to serve as adulterants (<17%) have been analyzed. Using a laser diode as a source light, the fluorescence emission has been measured and 20 chaotic parameters from the resulting spectra have been calculated. Using these as independent variables of multi-parameter regression models, the concentration of adulterant has been estimated. Every model was evaluated through the mean square error, adjusted correlation coefficient, Mallows’ Cp, Akaike information criterion, Hannan-Quinn criterion, and Bayesian information criterion. This approach was validated by the leave-one-out cross-validation method and the results were promising (lower than 10% quantification error). Additionally, the structure of the sensor has been designed and developed by a 3D printer and has the potential of being applied in situ for real-time and cost-effective analysis at oil mills or for quality control.