Sustainable multifunctional packaging films based on chitosan and food waste-derived carbon nanodots for fruit preservation

Chitosan (CS), an abundant and biodegradable natural polymer, represents a highly valuable alternative to non-biodegradable packaging materials. But it is limited by unsatisfactory mechanical, barrier, and antibacterial properties. Food waste is rich in active ingredients. Using them for food preservation not only facilitates a closed-loop of resource utilization but also reduces dependence on traditional preservatives, providing a more eco-friendly and sustainable solution. In this study, nitrogen-doped carbon dots (N-CDs) were synthesized from orange peel waste via a green hydrothermal method. Sustainable multifunctional composite films were prepared by compounding N-CDs with chitosan (CS). The results showed that adding N-CDs enhanced the mechanical properties, UV protection, water barrier, antibacterial activity, and antioxidant capabilities of the composite films. Furthermore, the films also exhibited good humidity-responsive fluorescent sensing capability, making them suitable for smart humidity monitoring. When used for fruit preservation, the composite films could effectively extend the shelf life. This study of multifunctional packaging films composed of seafood waste (CS) and fruit waste (N-CDs) providing an easy approach for the high-value utilization of food waste and the sustainable development of food packaging materials.