Alginate and pectin composite films crosslinked with Ca2+ ions: Effect of the plasticizer concentration

The manufacture of composite biofilms of alginate and LM-pectin crosslinked with calcium ions requires a two-step contact with Ca2+: initially a low-structured pre-film is formatted which is further crosslinked in a second contact with a more concentrated Ca2+ solution containing plasticizer. This research evaluated the influence of the plasticizer (glycerol) concentration (1-15% w/v) in this finishing reticulation step on final films characteristics. The results indicated that the extent of the simultaneous Ca2+ crosslinking and plasticization with glycerol was determined by the level of structural organization obtained in the pre-reticulation. Increasing the glycerol concentration of the crosslinking solution increased film solubility in water, moisture content, volumetric swelling and flexibility and decreased the resistance to tensile stress. Transparent alginate and pectin composite films with acceptable mechanical properties, low solubility and limited degree of swelling were obtained with 10% glycerol in the second contact solution. (C) 2009 Elsevier Ltd. All rights reserved.