NATURAL AND APPLIED WAX COATINGS ON ORANGES

Scanning electron microscopy was used to examine the wax coating on oranges. The natural wax platelets are irregular in shape and size, have a rough surface and increase in numbers as the orange matures. Most natural platelets can be removed by dipping the orange in a chloroform-methanol solution and rubbing the surface. Store-bought oranges have natural wax platelets 1–2 microns thick covered with a 2–5 micron layer of commercial wax. Wax applied over platelets may be ineffective if the platelets break off in handling and expose the orange's surface. Removal of natural wax platelets prior to commercial waxing allows uniform wax application and consequently better storage life. Drying with air at 2.5 m/s produced uneven wax thickness while 14 m/s air produced a complete, uniform wax layer.