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 hyrophile-lipophile balance of 6.0 as the dispersed phase, The effect an 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/kPa.d.m(2) 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 63.6.g.mm/kPa.d.m(2) obtained with an 82-53% relative humidity gradient.