Graphene-Oxide-Infused Marine Biopolymers: Layer-by-Layer Assembled Nanocomposite Packaging for Prolonged Fresh-Cut Apple Preservation

Considering the ecological and environmental issues caused by petroleum-based plastics for packaging fresh-cut fruits and vegetables (FFVs), there is an urgent need to develop sustainable and ecofriendly active packaging. Therefore, marine-derived biodegradable carboxymethyl chitosan (CMC) and sodium alginate (SA) were used to construct a layer-by-layer assembly system. Then, graphene oxide (GO) was introduced into the SA layer to produce (CMC/SA)n@GOx composite films. The impacts of the GO content (x) and assembly layers (n) were investigated on the internal interactions, microstructure, and packaging properties of the multilayer films. The rise of x and n leads to the increase of the microregion size and interface thickness in the films, and the introduction of GO into the SA layer enhanced its attraction to the CMC layer. With variations in both x and n, the (CMC/SA)19@GO5 film exhibited the greatest mechanical and barrier properties, along with enhanced UV-shielding capacity. Based on the above result, three different (CMC/SA)n@GOx films were selected for fresh-cut apple packaging, with transcriptomics used to investigate preservation mechanisms. The results showed that the (CMC/SA)19@GO5 packaging performed with the best physiological quality due to its high barrier properties, resulting in lower weight loss, reduced browning, and improved hardness. This was attributed to enhanced antioxidant capacity and resistance to wounding stress as well as delayed cell wall degradation and terpenoid biosynthesis, extending the shelf life of fresh-cut apples. In conclusion, this study demonstrated the potential of green packaging based on marine biopolymers for FFV preservation.