Characterisation of the Turkish and Slovenian extra virgin olive oils by chemometric analysis of the presaturation 1H NMR spectra

Abstract

Monovarietal extra virgin olive oils from 3 major Turkish cultivars (Gemlik, Ayvalık, Memecik) and 1 Slovenian cultivar (Bianchera) were analysed by standard and presaturation proton NMR experiments. In the latter method, signals arising from major lipid fractions upfield of 5.6 ppm were suppressed and, compared to standard proton experiment, considerable improvement was achieved in the intensities of the signals downfield of 5.6 ppm. For each sample, specific data sets were achieved by replacing the 0.04-ppm integration buckets in the region of 5.6–10.0 ppm of standard proton spectra with that of presaturation experiment values. Multivariate statistical analyses showed that olive oils of different olive cultivars could be effectively classified based on their one-dimensional proton NMR profiles. The buckets containing the signals belonging to protons of aldehydes (9.0–10.0 ppm), phenolic compounds (6.0–7.0 ppm), terpenes (4.0–5.0 ppm) and diacylglycerols (3.8–4.2 ppm) were the major discriminants of the oils used in the study.