Valencia oranges [Citrus sinensis (L.) Osbeck cv. Valencia] and Marsh grapefruit [Citrus paradisi Macf.] were treated with single or double layers of coating. In cases where two coatings were applied, the first coating was a moisture-barrier wax; the second was either polyethylene wax or a mixture of shellac and resin ester. The inner coating reduced weight loss, and the outer coating imparted gloss. Fruit gloss, as measured by reflectometer, decreased more rapidly during 1 week at 20C with a single glossy coating than with the same coating applied as a second layer over a wax-based first coating. For citrus fruit, using resin ester or shellac as a high-gloss second coating tended to overly restrict the exchange of O2 and CO2; however, two layers of wax did not.
The shrinkage rate of `Marsh' grapefruit (Citrus paradisi Macf.), `Ambersweet' hybrid [(C. reticulata Blanco × C. paradisi Macf. × C. reticulata) × C. sinensis (L.) Osb.] and `Valencia' oranges [C. sinensis (L.) Osb.] was increased 50 % to 150% by washing the fruit with rotary brushes, but was not changed by hand-washing the fruit with cellulose sponges. Internal CO2 increased using both washing methods. Waxed fruit obtained from five Florida packinghouses and cleaned with rotary brushes and waxed had shrinkage rates the same as those of nonwashed controls. Thus, controlling the washing process is important to minimize shrinkage of fresh citrus fruit.