Physiological changes during postharvest ripening of durian fruit (Durio zibethinus Murray)

Postharvest changes in ethylene production, respiration, soluble solids, total sugars, starch, firmness, pectic substances and activities of polygacturonase (PG), pectinesterase (PE), beta-galactosidase (GAL) and cellulase in 'Chanee' durian fruits were followed at ambient conditions. The rise in ethylene production and respiratory climacteric coincided and simultaneously reached a maximum on the fourth day. Soluble solids and total sugars in the aril also increased concomitantly with the decrease in starch content. The rapid decrease in the aril firmness was accompanied by changes in pectic substances; an increase in the water-soluble fraction and a decrease in ammonium oxalate and alkali-soluble fractions. PG and PE activities increased rapidly, while GAL and cellulase activities increased slightly. The increase in PG activity appeared more significant than that of the PE, GAL and cellulase activities.