The First Identification of the Uniqueness and Authentication of Maltese Extra Virgin Olive Oil Using 3D-Fluorescence Spectroscopy Coupled with Multi-Way Data Analysis

Abstract

The potential application of multivariate three-way data analysis techniques, namely parallel factor analysis (PARAFAC) and discriminant multi-way partial least squares regression (DN-PLSR), on three-dimensional excitation emission matrix (3D-EEM) fluorescent data were used to identify the uniqueness and authenticity of Maltese extra virgin olive oil (EVOO). A non-negativity constrained PARAFAC model revealed that a four-component model provided the most appropriate solution. Examination of the extracted components in mode 2 and 3 showed that these belonged to different fluorophores present in extra virgin olive oil. Application of linear discriminate analysis (LDA) and binary logistic regression analysis on the concentration of the four extracted fluorophores, showed that it is possible to discriminate Maltese EVOOs from non-Maltese EVOOs. The application of DN-PLSR provided superior means for discrimination of Maltese EVOOs. Further inspection of the extracted latent variables and their variable importance plots (VIPs) provided strong proof of the existence of four types of fluorophores present in EVOOs and their potential application for the discrimination of Maltese EVOOs.

Non-destructive Fluorescence Spectroscopy as a Tool for Discriminating Between Olive Oils According to Agronomic Practices and for Assessing Quality Parameters

“…Other less intense maxima were found at higher excitation wavelengths. The obtained EEMs are similar to those found in existing literature (Guimet et al 2004b;Jiménez-Carvelo et al 2019;Lia et al 2020). According to the conclusions of these prior studies, the first fluorescence band may be related to vitamins and oxidation products, whilst the second band appears to be correlated with chlorophyll derivatives.…”

Application of 1H and 13C NMR Fingerprinting as a Tool for the Authentication of Maltese Extra Virgin Olive Oil

“…The chemical shifts are expressed in d scale (ppm), referenced to the residual signal of chloroform. For 1 H NMR, this was found at 7.24 ppm [ 21 ] whilst for 13 C NMR, this was found as a triplet centerd around 77.01 ppm [ 22 ]. The corrected spectra were exported as ASCII files from Topspin 3.5 (TopSpin™ version 5, Bruker, Billerica, MA, USA) and imported directly into The Unscrambler X 10.3 (CAMO Software, Oslo, Norway) for all subsequent mathematical data processing.…”

“…Considering the small state of the market, mislabeled EVOO originating from other countries sold as Maltese EVOO could severely impede the growth of the industry, with severe negative economic repercussions. Recent studies have shown that Maltese EVOOs have a significantly different phenolic composition and mineral composition [ 20 , 21 , 22 ]. In this study, a variety of olive oils selected from different areas around the Maltese islands and countries around the Mediterranean were studied.…”

Nuclear magnetic resonance spectroscopy in extra virgin olive oil authentication

“…Synchronous fluorescence spectroscopy was found to be a useful tool coupled with multivariate statistical analysis to detect and quantitatively assess EVOO adulteration (Nigri & Oumeddour, 2016; Poulli et al., 2007). A development of this technique is 3D‐excitation‐emission matrix fluorescence spectroscopy, which is widely used in food areas because of its rapidity and simplicity, coupled with chemometrics, mostly parallel factor analysis (Lia, Formosa, et al., 2020; Xu et al., 2015). Fourier transform infrared spectroscopy (Aykas et al., 2020; Christy & Egeberg, 2006; Karunathilaka et al., 2016; Rohman & Man, 2010) coupled with attenuated total reflection (Poiana et al., 2015) has been adopted not only for research purposes but also by industries.…”