Establishment of mass storage technology of middle and late-maturing citruses covering storage at container unit using perforated polyethylene films

With regard to middle and late-maturing citruses (summer orange, Citrus iyo and Citrus hassaku) that are cultivated at the long north district that faces the side of Japan Sea of Yamaguchi prefecture, because the storagelasts for a long term, it is general to use individual packaging in polyethylene films. However, the method to store a fruit one by one necessitates a lot of efforts in the pretreatment before storage and in removal of bags at the delivery. Therefore, about summer orange, Citrus iyo and Citrus hassaku, covering materials and treatment methods were investigated that were appropriate for the storage at container unit and that had the equivalent storage properties as that of the storage to put the fruit one by one in a polyethylene bag, In each case, the temperature condition of storage should be the same as the case of individual packaging in polyethylene films. As for summer orange, 3-4% of pretreatment was carried out for fruits which were harvested in mid-January, and it was considered that the storage could be made in very close conditions with those in case of individual packaging by polyethylene films for a long period until early June where improved perforated polyethylene films were spread in the container and fruits were fully packed in which the number of perforation was decreased to the half of ready-made perforated polyethylene films (there were perforations with the diameter of 1.8mm and with the interval of about 2.0 * 1.5cm, and 0.05mm of film thickness). As for Citrus hassaku, without pretreatment for fruits which had been harvested in late December, and it was considered that the storage was possible until early April by using perforated polyethylene films with improvements in which the number of perforation was decreased to one-third of ready-made perforated polyethylene films. The time of material covering ouold be reduced to one-third of the case of individual packaging.