Water Vapor Permeability of an Emulsion Coating of Maltodextrin and Surfactants

Emulsion coatings were formulated mainly using maltodextrin as the structural material and a blend of surface-active compounds with a hydrophile-lipophile balance of 6.0 as the dispersed phase. The effect on the water vapor permeability of the coatings was determined as a function of disperse phase concentration, film thickness and relative humidity gradient. Results showed that the coatings were stable even in relative humidity gradients of 92–86%. Water vapor permeability values increased from 23.4 to 45.3 g × mm/kPadm2 when the dispersed phase was reduced from 0.20 to 0.10. A relative humidity gradient of 92–86% produced a permeability of 79.6, higher than 63.6gmm/kPadm2 obtained with an 82–53% relative humidity gradient.