Some Studies on the Cuticular Wax of Citrus Fruits

Some preliminary data on the natural wax coat of citrus fruits are presented. Thin-layer and column chromatography showed that the main differences from apple and grape waxes were the relatively higher percentage of esters, the lower percentage of alcohols and the apparent lack of triterpenoids. During fruit development in the Shamouti orange wax production was approximately balanced by surface growth, sos that the amount of wax per unit surface of rind was approximately constant for most of this period. When fruit growth was slowed down by winter temperatures and incipient senescence, the amount of wax per unit surface increased. Wax production continued (possibly at a greater rate) after the fruit had been severed from the tree. Wax removal was enhanced by successive treatments with chloroform. Weight losses of fruit in storage were proportional to the number of wax removals. Packing-house treatments did not remove natural wax but seemed to check its secretion by rind cells.