Self-Reinforced and Antibacterial Zn2+ @Vanillin/Carboxymethyl Chitosan Film for Food Packaging

Polysaccharide-based films cannot replace petroleum-based food packaging due to their poor mechanical properties, and the lack of antibacterial properties also makes it difficult to extend the food shelf life. Herein, we used the Schiff base reaction and zinc ion (Zn2+) complexation on carboxymethyl chitosan (CMCS) chains to introduce antibacterial properties to extend the shelf life of food and achieved self-reinforcement to improve mechanical properties, reaching 7.28 MPa and making it suitable for food packaging. The Zn2+@Vanillin (VA)/CMCS film possessed broad-spectrum antibacterial properties that extended the shelf life of fruits and offered better thermal stability and water vapor barrier. Besides, it also provides more comprehensive protection and inhibits the respiration of fruits during the preservation process that maintains the quality of the fruits. In addition, the process for the preparation of the Zn2+@VA/CMCS film was environmentally friendly (the solvent is water), safe, and simple and had mild reaction conditions. Noteworthily, the Zn2+@VA/CMCS film possessed biodegradability (35 days in soil) and renewable characteristics that offer significant potential for the development of sustainable food packaging systems.