Characterization of starch, agar and maltodextrin blends for controlled dissolution of edible films.

Biopolymer blend interactions influence the physical, mechanical and barrier properties of edible packaging. Starch (rice and hydroxypropyl cassava starch mixture), agar and maltodextrin were formulated to control the solubility of edible films. Blend materials were characterized for fluid rheology, solid microstructure, mechanical barrier and physical properties. Agar enhanced solid behavior and governed low temperature gelation of the blends, giving improved film forming ability and hydrophobicity. Flexibility of the films highly depended on integrity of polymer networks. Agar formed continuous networks entangled in starch matrices. Conversely, maltodextrin acted as a filler that reduced mechanical strength at high concentration (>40%) due to interruption of network integrity. Interaction between starch and agar led to poor water solubility that was insignificantly impacted by agar concentration (10% to 30%) due to identical molecular bonding. Maltodextrin produced highly miscible and plasticized starch-agar films and led to reduced mechanical relaxation temperature and shriveling of film structures after mold dipping. Solubility increased linearly with higher maltodextrin concentration. Molecular interaction between maltodextrin and starch/agar matrices insignificantly influenced solubility, while strong interaction between starch and agar highly controlled solubility. Findings clarified the interaction mechanisms and behavior of biological macromolecule materials in fluids and solid matrices for manufacture of edible packaging.