Changes in pectic substances and cell wall hydrolase enzymes of mangosteen (Garcinia mangostana) fruit during storage

Mangosteen (Garcinia mangostana) fruits at mature green stage with 5% red spotting were held at room temperature (31-35 degrees C, 84 +/- 2% relative humidity (RH)) and at the storage temperature of 13 degrees C (90 +/- 2% RH). Firmness, pectin content, and activities of pectin methylesterase and polygalacturonase in the pulp (aril) were monitored every 2 days. Pulp firmness rapidly decreased at room temperature from day 0 to day 4 after storage and slightly decreased thereafter, whereas pulp firmness slowly decreased at 13 degrees C. Water soluble pectin content in pulp increased more rapidly at room temperature than at 13 degrees C. Insoluble pectin content in pulp decreased throughout the storage time at both storage conditions. Both pectin methylesterase and polygalacturonase activities in pulp increased more rapidly at room temperature than at 13 degrees C. Changes in water soluble pectin and cell wall hydrolase enzymes in relation to pulp softening of mangosteen fruits are discussed.