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, Caastiglionese, Nebbio and Grossa di Cassano. Such a vegetal 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 higer than those available in the literature for the corresponding olive fruits. The amounts of oleuropein in the leaves were markedly modified by the colour/age and genetic factors, whereas meaningless were ascribable to the quantisation method and collecting period factors. Various chemometrics, applied to the obtained analytical data appeared to be effective in discriminating the samples on the basis of above examined experimental factors, thus confirm how they should be carefully taken into account in future industrial recovery of oleuropein from olive leaves.