GROWTH AND COMPOSITIONAL CHANGES DURING THE DEVELOPMENT OF PRICKLY PEAR FRUIT

Growth and compositional changes in prickly pear (Opuntia spp.) fruit during the development of four species (O. ficus-indica, O. inermis, O. hyptiacantha and O. lindheimeri) were studied. The weight and size of fruits belonging to O. ficus-indica, O. hyptiacantha and O. lindheimeri generally followed a single sigmoid growth pattern while fruits belonging to O. inermis followed a double sigmoid growth pattern. In all species, soluble solids and ascorbic acid contents increased with a concomitant decrease in titratable acidity as fruits matured. O. hyptiacantha consistently had the highest soluble solids and ascorbic acid contents and the lowest titratable acidity while O. lindeimeri consistently had the lowest soluble solids and ascorbic acid contents and highest titratable acidity throughout ontogeny. Although significant differences in soluble solids and ascorbic acid contents were observed, all four prickly pear species exhibited similar trends in compositional changes with growth. Attributes that contributed to fruit flavour such as sugar to acid ratio positively correlated with attributes that contributed to eating quality such as sugar and ascorbic acid content. The attainment of the characteristic fruit colours is highly species-specific and dependent on the number of days after fruit set.