Softening of durian cultivars

The activities of the enzymes polygalactosidase, pectinesterase, beta-galactosidase and cellulase were assayed during aril softening of durian (Durio zibethinus Murray) cvs. Chanee and Monthong. The aril of both 'Chanee' and 'Monthong' durians softened continuously throughout the ripening period and coincided with a marked increase in water-soluble pectin, polygalacturonase and pectinesterase activities, while beta-galactosidase and cellulase activities were relatively high at picking time and slightly increased during ripening. The aril of 'Monthong' durian was firmer and contained less water-soluble: pectin and pectinesterase activity than that of 'Chanee' durian, while their polygalacturonase activities were comparable during ripening.