Papaya Polygalacturonase and its Role in Thermally Injured Ripening Fruit

Abstract
The polygalacturonase (E.C. 3.2.1.15) (PGase) activity in papayas increased with fruit ripeness. PGase activity was highest in the placenta with the activity decreasing outwardly from the placenta to the exocarp. Extended hot water treatments (46°C for 65 and 90 min) caused delayed softening of the fruit tissue which was correlated to a decrease in PGase activity. The decrease in PGase activity after the heat treatments was more severe in the riper fruits (quarter and half ripe) than the less ripe fruits (colorbreak stage).