Physical, morphological and chemical changes during fruit development and ripening in three cultivars of prickly pear Opuntia ficus-indica (L.) Miller

Late ripening fruits of prickly pear cvs Gialla, Rossa and Bianca took 80-90 days from flowering to harvestable maturity. A decrease in fruit growth rate occurred from 30 to about 60 d after flowering, during the period of seeds development and hardening. The fruit continued to grow both on a fresh and dry weight basis until maturity. The greatest development of the core occurred from 50 d after flowering. During the same period there were consistent changes in biochemical activity: the total sugar content and the total soluble sugars (TSS) sharply increased whilst the fruit firmness and the total tritratable acids (TTA) decreased. Fruits reached the optimum maturity stage when TSS reached a "steady state" over 13% Brix; this stage corresponds to the period of peel colour breakage. From 90 d after flowering onwards the fruits became tender and unsuitable for processing and storage. At that stage the peel was fully coloured.