Quality parameters of black and red currants during ripening

Color parameters, pH value, the content of sugars, organic acids and polyphenols were monitored during the ripening of red and black currant berries. The content of organic acids declined and the content of sugars increased significantly during currant maturation. A decline in the content of total hydroxycinnamic acids and flavonols has been observed in red currant fruit during ripening. On the other hand, increased levels of hydroxycinnamic acids, ellagic acid and flavonols have been measured in black currants during ripening. The changes in the levels of individual phenolic groups also affected total phenolic content and antioxidative activity of ripening currants. The results indicate that a simple index for determining optimal currant ripeness could be formed based on the content of individual phenolic groups and the sugar/organic acid ratio.