MOISTURE PERMEABILITY OF EDIBLE FILMS MADE WITH FATTY-ACID AND (HYDROXYPROPYL)METHYLCELLULOSE

Edible films made up of 55% (hydroxypropyl) methylcellulose and 45% stearic acid had permeability of 0.17 ± 0.04 g mil/(m2 day mmHg), evaluated with 85% relative humidity on one side of the film, 0% on the other. The permeability was unchanged at 94% relative humidity. It was higher at 97–99% relative humidity and also higher if shorter chain fatty acids were substituted for stearic acid. Permeability increased 10-fold when stearic acid crystals were removed from the surfaces of the film. The permeability was higher when the more crystalline side was toward the high-humidity atmosphere. Tensile strength of the film decreased rapidly at values of relative humidity above 90% on both sides of the film. © 1990, American Chemical Society. All rights reserved.