Assessment of a maturity index in jabuticaba fruit by the evaluation of phenolic compounds, essential oil components, sugar content and total acidity

Abstract

Jabuticaba is a Brazilian tree with edible grape like fruits which are consumed fresh or used to prepare jams, liqueurs and wines. The aim of this study was to identify the optimal harvest period for winemaking by monitoring chemical parameters during jabuticaba's development. Jabuticaba fruit was analysed at four developmental stages for total acidity, reducing sugars, anthocyanins, tannins, total phenols and essential oi! composition. Total acidity significantly decreased (15.46-4.56 g citric acid 100 g-1), whereas reducing sugars increased about threefold in pulps up until the full ripe stage (32.52-88.92 g glucose equivalent 100 g-1). Anthocyanin leveis underwent a sharp increase in the skins reaching 22.0 mg cyanidin 3-glucoside equivalent g-1 at complete maturation. Tannins and total phenols showed no significant differences in their leveis between ripe and full ripe stages. The essential oi! contains 88.1% of sesquiterpene compounds, being y-eudesmol (33.9%) and a-eudesmol (15.5%) the major constituents. Some minar terpenoids changed significantly in their contents during jabuticaba's maturation. The monoterpenes a-pinene, p-pinene, (E)-P-ocimene, linalool and a-terpineol increased while the sesquiterpenes amorpha-4, 7(11)-diene, õ-amorphene, õ-cadinene and a-cadinene decreased from green to ripe stages. However the major terpenoids showed no significant changes. Results demonstrated that the use of sugar/acid ratio and anthocyanin concentration seemed to be the most effective parameters to reveal the optimal harvest period for winemaking.