Gas Permeability of Fruit Coating Waxes

Abstract

The permeability to O 2 , CO 2 , C 2 H 4 , and water vapor was determined for 19 commercial fruit wax coatings, four ingredients thereof, and one shrink-wrap film. For the commercial coatings, the O 2 permeability at 50% relative humidity and 30C ranged from 470 to 22,000 ml (STP) × mil/(m 2 × day × atm) (1 mil = 0.0254 mm) with CO) 2 . permeability two to eight times as high. Permeability to noncondensable gases tended to be higher for coatings made from carnauba wax than for those made from shellac and rosin. Commercial fruit wax had sufficiently low noncondensable gas permeability to account for large reductions in the respiration rate of coated fruit. Wax coatings could be improved if permeability were controlled: