Phenolic profiles, oil amount and sugar content during olive ripening of three typical Tuscan cultivars to detect the best harvesting time for oil production

This work deals with the evolution of the phenolic profile in olive fruits of three typical Tuscan cultivars, Frantoio, Moraiolo and Leccino, during the ripening period (September and end of November). The main goals were to study the possible relationships between phenol, total sugar and oil contents in the fruit to determine the best harvesting time for oil production. The analysis by HPLC/DAD/ESI/MS enabled the assessment of the evolution during ripening for 20 different phenolic compounds. The presence of lignans and dialdehydic form of decarboxymethyl oleuropein aglycone (3,4-DHPEA-EDA) was excluded in all these fruits. In terms of total phenols, Moraiolo was always the richest cultivar with concentrations ranging between 12.1 and 21.3 g kg- 1; the phenolic reduction was scarcely appreciable in Frantoio, while for Moraiolo and Leccino the decrease was almost inversely related to the ripening time. For every cultivar the oleuropein trend was compared with the sugar and oil contents over time. By the statistical evaluation (correlation coefficient approach) inverse relations between the sugar amount and the oil content and significant relations between two minor phenols (chlorogenic acid, tyrosol) and the oil amount have been highlighted for each cv.