Bitter and volatile compounds in ethylene-treated Citrus grandis [L.] Osbeck fruits

'Suisho- buntan' (Citrus grandis [L.] Osbeck) fruits were treated with 0,20 and 40ppm ethylene for 72 hr in the dark. After the treatment, the coloring and the secondary metabolites (naringin and volatile compounds) of 'Suisho-buntan' fruits were investigated. The 20 and 40 ppm ethylene-treated fruits advanced degreening of the fruit, compared with the untreated fruits. Analyses for naringin and volatile compounds by HPLC and capillary GC and GC- MS, respectively, revealed that ethylene treatment or the exposure period had no effect on the amount of naringin and the flavoring compounds of coldpressed oils (CPO) in the fruits. These results suggest that exposure of 'Suisho-buntan' to 20 and 40 ppm ethylene for 72 hr is useful for degreening of fruit for shipment to the market.