Author : Sripan Cheyglinted

Summary : Two experiments were conducted at the Postharvest Laboratory of the Horticulture Research Institute in Bangkok, Thailand to determine the effect of ethephon on the physico-chemical changes during the ripening of "chanee" durian harvested at different maturities. "Chanee" durian fruits harvested at 75 percent maturity either failed to ripen or ripened abnormally, although there was an apparent climacteric rise in respiration and ethylene production. The sensory characteristics and other ripening parameters were inferior relative to more mature fruits. Fruits at 85 percent and 95 percent maturity had good eating quality at the table-ripe stage (TRS) which was attained 3 and 2 days after harvest (DAH), respectively. Normal ripening, (i.e. yellowing of the pulp and development of full flavor and aroma of fruits harvested at 75 percent maturity) was obtained at TRS if treated with 1,000 or 2,000 ppm ethephon. For all ethephon concentrations tried, internal ethylene production of fruits, irrespective of harvest maturity, was not enhanced. However, ethephon treatment consistently advanced the onset of the respiratory climacteric in fruits harvested before they were 95 percent mature. Ethephon treatment was no longer effective when used on fruits harvested at 95 percent maturity. Thus, it appeared that the failure of immature fruits to ripen normally could be attributed to a lower sensitivity to lower amount of ethylene. The immature fruit requires a level of ethylene higher than the endogenous level normally produced to elicit the normal ripening responses. Three days after harvest, ethephon treated fruits at 75 percent maturity were rated higher in firmness by mouthfeel than fruits at 85 percent and 95 percent maturity, regardless of treatment. This indicated that harvesting at 75 percent maturity combined with ethylene treatment extended shelf life of durian fruits by one day.