Moroccan extra virgin argan oil authentication by using ultraviolet–visible and front face fluorescence spectroscopies combined with different descriptive and predictive chemometric tools

Abstract

This study investigates the feasibility of using front face fluorescence (FFFS) and ultraviolet–visible (UV–visible) spectroscopies to authenticate 100 extra virgin argan oil (EVAO) samples from five Moroccan regions (Chtouka, Essaouira, Sidi Ifni, Taroudant, and Tiznit). Additionally, the study aims to identify and predict the percentage of adulteration in pure EVAO samples from these regions using less expensive vegetable oils (such as peanut, walnut, hazelnut, sunflower, grape, rapeseed, sesame, olive, and a mixture of these oils) at varying levels (1, 5, 10, 20, 30, 40 and 50%). By applying principal component analysis and factorial discriminant analysis on emission spectra acquired after excitation wavelengths set at 430 nm, 290 nm, and 270 nm, a perfect discrimination of EVAO samples based on their geographic origin was observed, achieving 100% correct classification; while UV–visible spectra data achieved 98.67% correct classification. Regarding the prediction of purity level of EVAO, partial least square regression applied to FFFS and UV–visible spectra data yielded an excellent prediction of adulteration level, with R² values of 0.99 for both spectral technics.