Development of Chemometric Models Based on a LC-qToF-MS Approach to Verify the Geographic Origin of Virgin Olive Oil

Abstract

In the presented study a non-targeted approach using high-performance liquid chromatography coupled to electrospray ionization quadrupole time-of-flight mass spectrometry (HPLC-ESI-qToF-MS) combined with chemometric techniques was used to build a statistical model to verify the geographic origin of virgin olive oils. The sample preparation by means of liquid/liquid extraction of polar compounds was optimized regarding the number of multiple extractions, application of ultrasonic treatment and temperature during concentration of the analytes. The presented workflow for data processing aimed to identify the most predictive features and was applied to a set of 95 olive oils from Spain, Italy, Portugal and Greece. Different strategies for data reduction and multivariate analysis were compared. Stepwise variable selection showed for both applied multivariate models—linear discriminant analysis (LDA) and logit regression (LR)—to be the most suitable variable selection strategy. The 10-fold cross validation of the LDA showed a classification rate of 83.1% for the test set. For the LR models the prediction accuracy of the test set was even higher with values of 90.4% (Portugal), 86.2% (Italy), 93.8% (Greece) and 88.3% (Spain). Moreover, the reduction of features allows an easier following up strategy for identification of the unknowns and defining marker substances.

The potential of wild olive leaves (Olea europaea L. subsp. oleaster) addition as a functional additive in olive oil production: the effects on bioactive and nutraceutical compounds using LC–ESI–QTOF/MS

“…Liquid–liquid extraction was used for the extraction of phenolic chemicals [ 48 ]. In brief, 2 g of sample material was precisely weighed into a 10 ml glass tube, then 5 ml MeOH/H2O (80/20 (v/v) was added, the mixture was shaken for 1 min (Vortex, 1500 Mot/min), then centrifuged for 15 min at 3000 rpm.…”

“…Finally, the combined extract's solvent was evaporated under nitrogen at 40 °C, and the residue was dissolved in 500 μliters of MeOH/H 2 O (50/50 (v/v)). The dissolved extract was shaken for 1 min (Vortex (1500 Mot/min), then filtered using a syringe filter (PTFE 0.2 m, WICOM Germany GmbH, Heppenheim, Germany), and then transferred to a vial for injection into the HPLC–DAD or HPLC–ESI–QToF–MS system [ 48 ].…”

Discriminant Analysis of the Geographical Origin of Asian Red Pepper Powders Using Second-Derivative FT-IR Spectroscopy

“…Each country has a different crop cultivation environment, such as soil and climate, which lead to differences in the metabolite compositions of plants. Therefore, many studies have been conducted to discriminate foods and agricultural products based on their geographical origins by analyzing their metabolite profiles using mass spectrometry (MS) [ 9 ], nuclear magnetic resonance (NMR) spectroscopy [ 10 , 11 ], and chromatography [ 12 ]. Recently, simple non-destructive Fourier-transform infrared (FT-IR) spectroscopic techniques have been used for metabolite research [ 13 , 14 ].…”

New Insights into the Specificity, Authenticity, and Traceability Analysis of Olive Oils

“…Despite the aim of this Special Issue encompassing three key topics-specificity, authenticity, and adulteration-no contributions were received regarding the theme of specificity. Thus, this editorial has collected papers giving an interesting outlook on several promising methodologies, including NMR-based approaches [2,3], chromatographic techniques [4][5][6][7], and stable isotope analysis [8] combined with advanced statistical modelling techniques for addressing the geographic and varietal origin of olive oils and cultivar differentiation, highlighting the themes of authenticity and traceability. Researchers have also devoted their attention to some classes of target compounds that are present in olive oils, namely volatiles [6], n-alkanes and n-alkenes [5], triacylglycerols [2], and biophenols [7].…”

“…Another approach encompassed in this Special Issue covers the building of a specific 1 HNMR profiling database using monocultivar reference olive oil for the analysis of olive oil blends [3]. Additionally, to verify the geographic origin of virgin olive oil, an untargeted analysis using LC-qToF-MS was utilized in one study [4].…”