Development and characterization of composite edible films based on sodium alginate and pectin

The objective of this study was to characterize physical properties including thickness, colour, water vapour sorption kinetics and isotherms, water vapour permeability, tensile strength, elongation at break, and microstructure of composite films prepared by casting sodium alginate and low methoxy pectin at proportions of: 100-0%, 75-25%, 50-50%, 25-75%, and 0-100%. Combination of both polysaccharides gave continuous, homogenous and transparent films. All of analyzed films reached their state of equilibrium within the 24 h of adsorption time. Water sorption isotherms for all films had a sigmoidal shape and were not influenced by the film composition. Sorption kinetics and isotherms indicated hydrophilic character of investigated films. Statistically significant (p < 0.001) correlations were found between colour, water vapour permeability, tensile strength, elongation at break, and chemical composition (alginate and pectin) of composite films. A different internal arrangement was observed as a function of film composition. (C) 2012 Elsevier Ltd. All rights reserved.