# Chitosan Nanocomposite Coatings for Food, Paints, and Water Treatment Applications
## 4 Applications of Chitosan-Based Nanocomposites
### Shelf-Life Extension of Fruits and Vegetables
#### 4.3.1 Packaging Films  
One of the main research areas in food industries has focused on developing new packaging techniques capable of improving the post-harvest life of fresh foods based on their interaction with packaging. Such techniques are well-known as \"active packaging\". Active packaging can be defined as the incorporation of an active system/materials into packaging film or a container to maintain the quality or extend the shelf-life of food products. In particular, antimicrobial packaging is one of the most innovative and promising active packaging systems developed over the last decade, and these systems are capable of inhibiting microbial growth and action, leading to the maintenance of food quality with improved shelf-life [148; 151; 152]. Biopolymer-based packaging films have received considerable interest as an alternative packaging material to plastics. The bioplastics are usually degradable under appropriate conditions of moisture, temperature, and oxygen availability and do not produce any toxic residues. The problems associated with biodegradable polymers are three-fold (3P): performance, processing, and price. Problems due to \"performance and processing\" are universal to almost all biodegradable polymers irrespective of their origin [153]. In particular, brittleness, low heat-distortion temperature, high gas and vapour barrier properties, and poor resistance to harsh processing operations have strongly limited extensive applications of biopolymers. The application of nanotechnology has opened new options for improving properties of biopolymers. The incorporation of nanoscale materials as a filler into the biopolymer matrix have shown to markedly improve mechanical, thermal, barrier, and other physio-chemical properties, compared to the base polymers and conventional (microscale) composites [154]. Nano-sized fillers can be either inorganic or organic materials, such as clay (e.g., montmorillonite), natural antimicrobial agents (e.g., nisin), metal (e.g., silver, gold), and metal oxides (e.g., zinc oxide (ZnO), titanium dioxide (TiO\({}_{2}\))), to be the material of choice due to its antimicrobial activity, thermal stability and ability to improve mechanical properties of biopolymer films [147; 155; 156; 157; 153; 157]. Chitosan-ZnO hybrid coatings on polyethylene films have been reported to reduce growth of pathogenic bacteria and fungi [85], as well as increase the shelf life of okra (_Abelmoschus esculentus_) vegetables [158]. [PERSON] et al. developed a chitosan-TiO\({}_{2}\) composite film for the packaging of red grapes and evaluated antimicrobial activity against food-borne pathogenic microbes, namely _E. coli_, _S. aureus_, _Candidida albicans_, and _Aspergillus niger_[147]. Results showed that the chitosan-TiO\({}_{2}\) composite films were effective against all four tested microbes, with 100% sterilization within 12 h. The composite film could successfully protect red grapes from microbial infection thus enhancing their shelf-life (Figure 5). Recently, several other researchers have studied the fabrication, characterization, and application of chitosan-based nanocomposites films with antimicrobial properties for food packaging applications. A summary of recent work done on antimicrobial nanocomposite films and their applications in extending the shelf-life of fruits and vegetables are given in Table 4.  
Figure 5: Preservation of red grapes wrapped with (**a**) polyethylene film, (**b**) pure chitosan film, and (**c**) chitosan-TiO\({}_{2}\) film, stored at 37 \({}^{\circ}\)C for six days. (Reproduced with permission from [147], Copyright © 2017, Elsevier).