Uso alternativo dei sottoprodotti dell'olivicoltura. Recupero dell'oleuropeina dalle foglie di olivo. Nota 1: Fattori di variabilità del glucoside iridoide

In this study, for the first time, was not only evaluated the impact of the genetic factor on the contents of oleuropein in olive leaves but also the influence exerted by the colour/age of leaves (green, green-yellowish and yellow) and the collecting period (spring or autumn). A repetitive high-resolution gas chromatographic (HRGC) quantitation method and a high-performance liquid chromatographic (HPLC) one were developed. The studied analytical methods gave results showing a high linear relationship. Samples of olive leaves were taken from seven major Italian olive cultivars, such as Dritta, Leccino, Caroleo, Coratina, Castiglionese, Nebbio and Grossa di Cassano. Such a vegetable raw material could actually be exploited for recovering Oleuropein, considered to be a high-added value molecule, which could successively be converted in hydroxytyrosol, a compound known to possess strong bioactive properties. Olive leaves showed considerable contents of oleuropein, which with some cultivars were even higher than those available in the literature for corresponding olive fruits. The amounts of oleuropein in the leaves were markedly modified by the colour/age and genetic factors, whereas meaningless variations were ascribable for the quantisation method and the collecting period factors. Various chemometrics, applied to the obtained analytical data, appeared to be effective in discriminating the samples on the basis of the above examined experimental factors, thus confirming how they should be carefully taken into account in future industrial recovery of oleuropein from leaves