Relationships between activities of polygalacturonase, pectin methylesterase, cellulase and beta-galactosidase and pulp softening of ripe durians
1995
Tira Daengkanit
Relationships between activities of polygalacturonase (PG), pectin methylesterase (PME), cellulase and beta-galactosidase and pulp softening of ripe durians cv. Chanee harvested at 102 and 109 days and Monthong harvested at 116 and 123 days after anthesis were studied. The two cultivars ripened normally at ambient temperature. CO2 and C2H4 production increased gradually. Chanee harvested at 109 days reached a climacteric peak at day 4 whereas those harvested at 102 days and Monthong exhibited the peak at day 5 and CO2 and C2H4 production decreased thereafter. Pulp softening, soluble solids (SS) and water soluble pectin (WSP) contents of Chanee increased more rapidly than those of Monthong. Chanee harvested at 109 days had higher SS and WSP contents than those harvested at 102 days and Monthong fruits. The increase in PME and PG activities was accompanied by pulp softening and the increase in WSP content as ripening advanced. PME and PG activities in Chanee were higher than those of Monthong fruits. However, the PME activity was not significantly different between two different stages of maturity in both cultivars. The change in cellulase and beta-galactosidase activities apparently did not involve in pulp softening of both cultivars since cellulase showed high level of activity at initial time and remained constant and there was no consistent change in beta-galactosidase activity during ripening.
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