Characterization of edible packaging films based on semi-refined kappa-carrageenan plasticized with glycerol and sorbitol

Semi-refined kappa-carrageenan (SRC) based edible films plasticized with glycerol or sorbitol at 20, 25 and 30% (w/w) were prepared and characterized. SRC films containing plasticizers had higher tensile strength and elongation at break than the control (unplasticized) SRC film. Increased moisture content, water solubility and water vapor permeability were found in films plasticized with 25-30% of glycerol and 30% of sorbitol as compared to the control SRC film. Water sorption kinetics indicated that all plasticized films reached the equilibrium rate. Films were more transparent and their seal strength increased significantly, whilst, their oil permeability was reduced when the plasticizers concentration increased from 20 to 30%. Films plasticized with sorbitol were more effective oxygen barriers than films plasticized with glycerol. Scanning electron microscopy and atomic force microscopy showed that SRC films plasticized with sorbitol were more homogeneous and smoother than the control SRC film. This study showed that the inexpensive SRC is a promising packaging material and has good potential to be used as an alternative polysaccharide material for the production of edible biodegradable packaging films with improved mechanical and barrier properties. (C) 2016 Elsevier Ltd. All rights reserved.