The effect of fatty acid content on water vapour and carbon dioxide transmissions of cellulose-based edible films

Water vapour and CO2 transmissions of methyl cellulose (MC)-based edible films with varying amounts of the fatty acids, stearic acid (SA), palmitic acid (PA) and lauric acid (LA) were studied and the results were compared with those obtained for a film without added fatty acid. Water vapour transmission rate (WVTR), water vapour permeance (WVPN) and water vapour permeability (WVP) values of films were determined by measuring the amounts of water vapour transmitted through the film and then adsorbed on anhydrous CaCl2 as a function of time, using a static method. A recently-developed static method which utilises ascarite to adsorb carbon dioxide transmitted through the film was employed for the determination of carbon dioxide transmission rate (CO2TR), carbon dioxide permeance (CO2PN) and carbon dioxide permeability (CO2P) of films. Among the three fatty acids studied, SA was found to be the most effective in decreasing both the water vapour and the CO2 transmissions of films. In general, it was observed that WVTR, WVPN and WVP values of films decreased with increasing fatty acid content in the film composition. CO2 transmission parameters also decreased with increasing SA and PA contents but increased with increasing LA content of films.