Fabrication of pH-sensitive galactomannan/glycerol bio-composite films for food packaging applications

Polysaccharide has attracted tremendous attention for their potential applications in film material with biodegradable, non-toxic, and environmentally friendly. Herein, the novel degradable galactomannan composited films were fabricated by a simple one-pot method based on physically crosslinking hydrogen bonding interactions between the hydroxyl of Gleditsia sinensis polysaccharide gum (GSG) and glycerol (Gly). Meanwhile, the film was incorporated with dye ingredients (Methyl orange, MO; Methyl red, MR; Bromocresol green, BG) as responsive agents and displayed considerable pH-responsive behavior by simulating the contact under acidic and alkaline conditions. The WVP values of films directly related to the concentration of Gly, and the highest WVP value was determined to be 0.1153 g center dot mm/m2 center dot h center dot kPa. By taking mechanical property for emphasis, the composites film had decreased tensile stress (from 89.6 to 33.6 MPa) and significantly improved elongation rate (from 3.7% to 177.0%) with the increased Gly concentration, owing to the dynamic variation of inter- and intramolecular hydrogen bonds between GSG and Gly chains and the corresponding molecular motion. The results demonstrated the properties of a novel galactomannan composited film that can potentially be applied in food packaging.