Water-resistance chitosan film through enzymatic treatment and layer-by-layer assembly with bacterial cellulose for food packaging materials

The pervasive presence of plastic packaging has led to significant environmental contamination due to excessive reliance on petrochemicals and the inherent non-biodegradability of these materials. Both bacterial cellulose (BC) and chitosan (CT) films offer a promising option for food packaging purposes due to their sturdy mechanical strength, biodegradability, environmentally friendly manufacturing process, and non-toxic composition. However, the considerable moisture absorption capacity of these eco-friendly materials has hindered their extensive use, as it leads to a reduction in their strength and ability to serve as a barrier. In the present study, we introduced a composite material of BC reinforced with a lauryl gallate grafted CT coating. After grafting CT with lauryl gallate (CT-LG) through enzymatic modification, it showed excellent hydrophobic properties also in a green route of chemistry synthesis. Based on the results of the study, the duration of the water droplet test of the pure CT-LG film and BC coated with CT-LG (BC/CT-LG) films was more than 15 min, showing that water droplets can be completely blocked by the CT-LG coating without water penetration. For the mechanical properties, the wet flexural strength and wet tensile strength of BC/CT-LG films have improved 400% and 70% compared with the original BC. This method produces a composite material with enhanced hydrophobicity and green properties and shows great potential for use in drinking straws or packaging bags.