Sustainable Layer-by-Layer Films Using Chitosan Decorated With Anthocyanins and Carboxylated Graphene Oxide for Food Packaging Applications

The abuse of traditional plastic food packaging has caused severe food safety and environmental pollution, urgently necessitating the development of green and sustainable biodegradable packaging materials. Chitosan (CS) belongs to an inexpensive and readily available biopolymer; however, the poor mechanical properties and weak resistance to UV light and water make it unsuitable for the food packaging industry. In this study, a layer-by-layer (LBL) assembly of CS decorated with anthocyanins as a polycationic electrolyte and carboxylated graphene oxide (GO-COOH) as a polyanionic electrolyte is used to fabricate bio-based films with the aim of improving comprehensive properties of CS-based films. The results indicate that the LBL assembly extremely enhanced the UV-blocking ability (the average transmittance in the UV-B region drops to 1.68%), tensile strength (TS) (53.52 MPa), toughness (71.81%), thermal stability, water resistance, hydrophobicity (the water contact angle is up to 109.5°), and antioxidant activities of the films, attributed to hydrogen bonds among CS, anthocyanins, and GO-COOH and electrostatic interactions between GO-COOH and CS along with anthocyanins. In addition, the LBL films show exceptional advantages in the storage application for fresh-cut apples. In general, the study demonstrates that a novel and sustainable CS-based film can be fabricated by the LBL technique for food packaging.