Assessing tyrosol and hydroxytyrosol in Portuguese monovarietal olive oils: Revealing the nutraceutical potential by a combined spectroscopic and chromatographic techniques - based approach

Abstract

Aiming to address the claims of nutraceutical status described in the EU Regulation 432/2012 for Extra Virgin Olive Oils (EVOO), this work is focused on the assessment of total contents of tyrosol (Tyr) and hydroxytyrosol (HTyr) for Portuguese monovarietal olive oils. To achieve this main goal, a multi-technique-based approach was performed encompassing the use of a multiple suppression nuclear magnetic resonance (MS-NMR) experiment followed by chromatographic determinations using High Performance Liquid Chromatography (HPLC-DAD). NMR-based experiments enable to screening Tyr and HTyr and their derivatives using a non-destructive and straightforward methodology. Further quantification of their levels was performed by HPLC-DAD being preceded by a sample preparation pre-treatment. The results show that levels of those compounds in the EVOOs analyzed varies in the ranges 1.135–5.715 mg·20 g−1 (Tyr) and 0.651–5.259 mg·20 g−1 (HTyr). Thus, a nutraceutical status could be claim for the EVOO's from the varieties Picual, Cobrançosa, Verdeal Alentejana and Blanqueta.