REDUCTION IN GAS-EXCHANGE OF CITRUS-FRUIT BY WAX COATINGS

Grapefruits and oranges were coated with various fruit waxes. Compared to control, internal CO2 concentration was markedly higher and weight loss markedly lower for coated fruit. Resistance of coated fruit to passage of CO2 and water vapor was shown to be influenced by permeability of the coating but more so by the degree to which the coating seals openings in the fruit epidermis. For restriction of CO2 exchange the coating thickness and surface tension of liquid coating were of less importance than type of wax. Critical surface tension of grapefruit and orange peel, after washing, was 23 dyn/cm. Shellac coatings adversely affected fruit flavor.