Patterns of Fluorescence Associated with Citrus Peel Defects

Unshu citrus were sorted by fluorescence imaging in a commercial packinghouse and undamaged-appearing unshu that had been rejected by the packinghouse due to fluorescence appearing on their peel were studied. We examined the various visible patterns, based upon fluorescence and microscopic images, to provide a categorization of physical reasons for the observed fluorescence. The categorization classes were: 1) slight physical damage: thin scar, hole and flow, shrunken at calyx; 2) rubbing against decayed fruits; 3) green spots; and 4) rind puffing. The percentage of observation for each of the four classes was 22 %, 15 %, 42 % and 21 %, respectively. Storage of the classes indicated that, except for the green spot class, the injured area expanded quickly and caused the fruits to rot within a week.