The preparation and physicochemical properties of biodegradable konjac glucomannan-based films reinforced with bacterial cellulose and tea polyphenol for food packaging

Biodegradable and edible packaging films derived from konjac glucomannan (KGM) are gaining popularity as promising candidates to replace petroleum-based plastics with the aim of alleviating environmental problems. However, their poor mechanical strength and lack of antioxidant activity have restricted their practical application in food packaging. Bacterial cellulose (BC), with a three-dimensional nanostructure and biodegradable and biocompatible properties, was chosen as a reinforcing agent to enhance the mechanical properties of KGM film. Film prepared with 15% BC displayed the highest tensile strength of 62.87 MPa and elongation at break of 38.17%, owing to the strong hydrogen bond interactions between the BC and KGM chains. Furthermore, tea polyphenols (TP), a type of natural antioxidant agent, were incorporated into the BC and KGM composite films and endowed films with excellent antioxidant properties, with scavenging rates toward DPPH and ABTS free radicals of up to 96.74% and 97.50%, respectively. Meanwhile, the mechanical strength, UV shielding performance, and water-vapor and oxygen barrier properties of the films were also improved through the incorporation of TP. The film was successfully applied as a packaging material for fresh-cut apple preservation. The prepared film demonstrated nontoxicity and excellent biodegradability over 28 days, with no significant impact on plant growth. Therefore, the prepared composite film exhibited great prospects as a novel type of biodegradable, sustainable and bioactive film for food preservation.