Studies on the storage of hebezu fruits [Citrus sp.]

Hebezu (Citru sp.), one of the green citrus fruit varieties had rich acid content and good flavor, have been used for making a sauce or dressing for seafood in Japan. The qualities of these citrus fruits are estimated by the green color of the peel as same as sourness and flavor. As the green color of the fruit peel turn to yellow in short period after harvest and during marketing, the salable period was limited. When the fruit color change to yellow on October, the fruit prices go down rapidly. Controlling of the fruit color is the most important postharvest technology in this fruits and also beneficial technique both of the producers and the consumers. The fruits were harvested from early of August to late of September were stored at 1 to 21 deg C. Determination of the optimum harvest season, storage temperature and the fruit qualities such as the content of chlorophyll, citric acid, ascorbic acid were investigated. 1) The peel color was changed faster to yellow in the fruits stored at temperature above 10 deg C. The fruit showed the chilling injury symptoms as pitting and browning on the peel when stored lower than 6 deg C. The intensity and occurrence rate of chilling injury were reduced at latter harvest season fruits. 2) The respiratory rate was higher in the harvested fruits at early season than late season. The fruit respiration was temporary increased in a few days after storage and then decreased in all harvest season fruits. The rate of respiration increased associated with degreening or changing to yellow of the fruit rind at high storage temperature. The in creased of respiration was related to the development of chilling injury in early August harvested fruits stored at 5 or 6 deg C. While, in the fruit harvested at the late season, the respiration had slightly changed. The ethylene production was increased coincidentally in the same as peel color changes or deterioration of the fruit by chilling injury. 3) The chlorophyll content in the rind was reduced above 10 deg C and maintained below 5 deg C in August harvested fruits. In the fruits harvested at September, the chlorophyll content was decreased above 6 deg C and the reducing rate of chlorophyll content was faster depended on the delaying of harvest season. The ratio of juice content in the fruit was increased up on the delaying of harvest season, storage periods and the stage of fruit ripening. The citric acid and ascorbic acid contents in the fruit juice were not different at any harvest seasons and also not different at any storage temperature. 4) The fruits in CA and MA (film packaging) storage were remained green color and suppressed the reducing of chlorophyll content than that air stored fruits.