PAPAYA - Tropical Fruits - page 303

Fig. 11.7. The increase in papaya fruit total fresh weight and for skin, seeds and fl esh
(after Qiu et al. , 1995).
Flesh colour is white in immature fruit to a pale orange-yellow, salmon
pink or red, depending upon cultivar, when ripe. Total fruit starch declines
from 0.4% to less than 0.1% during the fi rst 80 days of fruit development
(Fig. 11.8). Sugars, however, do not begin to accumulate until 110 days from
anthesis, during the last 28-42 days of fruit development. Flesh total soluble
solids can be as low as 5% up to 19%.
Green fruit contains an abundance of milky latex that contains the
protease papain. The pericarp consists of a network of lacticifers that develop
close to the vascular bundles and anastomose profusely throughout the fruit.
This latex is under pressure and spurts out when the skin is pricked. Laticifers
collapse as the fruit ripens and there is little or no latex at the fully ripe stage.
Commercially, the skin is scarifi ed to induce latex fl ow, which is allowed to dry
then collected to be later processed into papain.
CULTIVAR DEVELOPMENT
Cytogenetics and genetics
The species in the genus Carica possess nine pairs of chromosomes and a small
genome (375 Mb). Meiosis is normal in the three sex types and there are no