NMR Fingerprint to Classify Spanish Olive Varieties

Traditionally the analysis of vegetable oils has been carried out by classic procedures such as gas chromatography, which requires previous derivatization of the sample. This, involves the consumption of reagents and, sometimes, the composition of the sample could be altered with the corresponding error in the measurement. Therefore, it is desirable to use faster and environmental friendly techniques that do not require manipulation of the sample. In this sense, the spectroscopic techniques are an alternative. Specifically, nuclear magnetic resonance (NMR) spectroscopy can be used in the field of olive oil to measure some of its characteristics (eg fatty acids, phenols, hydrocarbons, etc.).

The aim of this work have been to study the difference between samples of extra virgin olive oil of different varieties (picual, arbequina and verdial), based on the information provided by the ¹H and ¹³C spectra. The chemical shifts of the spectra were referenced with respect to tetramethylsilane, using the deuterated solvent signal as internal reference.

The data obtained have been treated by multivariate statistical analysis procedures (Multiple Analysis of Variance (MANOVA) and Principal Component Analysis (PCA)) to establish relations that have been interpreted from a chemical point of view and have allowed the discrimination of samples according to their variety.