Influence of maturity and postharvest treatment on the volatile profile and physiological properties of the durian (Durio zibethinus Murray) fruit

Variation in the volatile profile and physiological properties of durian (Durio zibethinus Murray cvs. Monthong and Chanee) were examined in fruits harvested at 100% (abscised) or 75-85% maturity, with the latter further subjected to various postharvest practices (i.e. Ethephon or 1-methylcyclopropene treatment followed by low temperature storage at 15°C, 75% RH). Consistent with literature, abscised and untreated 75-85% fruits kept in ambient condition (28°C, 75% RH) were the earliest to reach full maturity (dehiscent stage), with dehiscence observed a day earlier in Chanee for both maturities. Fruits kept in low temperature storage have delayed dehiscence, but exhibited the typical climacteric and normal ripening when transferred to ambient condition. Pulp texture of the fruits in all treatment groups reached the same degree of firmness upon dehiscence. Volatile profile analysis of dehiscent fruits by headspace solid phase microextraction coupled with gas chromatography-mass spectrometry revealed cultivar-specific variations. In Monthong, abscised and untreated 75-85% mature fruits ripened in ambient condition produced comparable levels of the major volatiles, while in Chanee, the levels of sulfur-containing compounds were decreased in 75-85% mature fruits. Ethephon-treated Chanee fruits kept in low temperature storage and transferred to ambient condition produced all the sulfur-containing volatiles upon dehiscence, while the 1-MCP-treated fruits were only detected of diethyl disulfide. Interestingly in Monthong, sulfur-containing volatiles production appears to be abolished in all fruits kept in low temperature storage. But, keeping these fruits for three more days in ambient condition recovered their capacity to produce the sulfur-containing compounds. On the other hand, all the major ester compounds were detected in all treatment groups, with the concentration of ethyl 2-methyl butanoate apparently enhanced in ethephon-treated fruits of both cultivars. The production of sulfur-containing volatiles exhibits a cultivarspecific sensitivity to low temperature storage and 1-MCP application. With further investigation, studies along this line may provide basis for the control of sulfur-containing volatiles in durian by the use of postharvest interventions.