Mid-Infrared spectroscopic characterization: New insights on bioactive molecules of Olea europaea L. leaves from selected Italian cultivars

Oleuropein and hydroxytyrosol, bioactive molecules present in olive leaves, are well known to have strong beneficial properties for human and animal welfare. Infrared spectroscopy combined to Principal Component Analysis was employed to determine, characterize at molecular level and classify olive leaf from five Italian cultivars (Caiazzana, Coratina, Ortice, Frantoio, Leccino) in the different portions (adaxial, abaxial, bulk). The aim of this study was to determine the spectral characteristics, by means of mid-infrared spectroscopy as a rapid tool, in the different portions of the olive leaves to better understand the distribution of the bioactive molecules and to compare the absorption spectra. The results obtained showed that the absorption spectra of the abaxial and adaxial surface of the leaves not only better detect the presence of biomolecules but also present higher levels of oleuropein and hydroxytyrosol for all cultivars analyzed. Therefore, the methods used are potentially useful for discriminating between the different cultivars, the different portions and the bioactive molecules present.