Abstract
The use of morpholine in fruit coatings in the U.S. is common, however ammonia can be used instead. Resin coatings were made from aqueous ammonia solutions of shellac and wood rosin. The affect of rosin coatings on internal gas concentrations was found to be highly variable, depending on the amount of plasticizer added--thus opening the possibility of developing a rosin coating of citrus fruit that is more flavorfriendly. Wax coatings were made from ammonia-based anionic microemulsions of various waxes, with emphasis on carnauba wax. Preparation of these microemulsions involved development of a new laboratory method for their preparation as well as selection of the most appropriate fatty acids. For carnauba-wax coatings, which consist partly of fatty acids, the optimum formulation consisted of a mixture of oleic, lauric and myristic acids, with total fatty acid content equal to about 14% of the wax. Carnauba wax coatings allowed for optimum exchange of gases on pummelo fruit. These ammonia-based fruit coatings were also successfully tested on apples, oranges and grapefruit. The results indicate that morpholine is not a necessary ingredient of fruit coatings.
