Chemical profile changes during myrtle (Myrtus communis L.) fruit development and ripening

The chemical composition of fruit belonging to ‘Barbara’ and ‘Daniela’ myrtle cultivars was monitored
during development from fruit-set to an over-ripe stage (July–January), with the aim to identify a reliable
maturity index. Acidity, pH, reducing and total sugars, phenols, tannins, anthocyans, carbon dioxide and
ethylene production rates were monitored over two different year seasons. Titratable acidity decreased
during maturation, with significant differences due to cultivar and year of observation. Reducing sugars
increased in both cultivars approximately sevenfold from fruit set to complete maturation. Total sugar
content increased similarly ranging from 1.43% and 1.41% at fruit set to 8.28% and 7.56% at maturation
for ‘Barbara’ and ‘Daniela’, respectively. Total phenols and tannins occurred at high levels after fruit set
and declined during development. Anthocyans levels increased, in both cultivars, according to a sigmoid
curve. The pattern of respiration rate showed a gradual decline in both cultivars ranging from 365.81
and 396.42mgkg−1 h−1 to 79.98 and 52.27mgkg−1 h−1, respectively for ‘Barbara’ and ‘Daniela’ in 2006. A
peak of variable size was observed in October–November period. Small increases in ethylene production
have been detected during fruit development ranging from 130.57 and 269.14Lkg−1 h−1 measured at
the onset of development to 13.04 and 19.36Lkg−1 h−1 measured at harvest for ‘Barbara’ and ‘Daniela’,
respectively.