# Chitosan Nanocomposite Coatings for Food, Paints, and Water Treatment Applications
## 4 Applications of Chitosan-Based Nanocomposites
### Shelf-Life Extension of Fruits and Vegetables  
During postharvest transportation and storage, fresh produce (fruits and vegetables) undergo quality deteriorations due to the various physiology reactions and processes, such as postharvest respiration, ripening, ethylene production, and senescence. These physiological changes are directly influenced by the surrounding environment, i.e., temperature, oxygen, humidity, and light, that lead to loss of water, texture, colour, and nutrients of the produce [142; 143]. Microbiological spoilage leads to postharvest losses of about 15% to 50% of fruits and vegetables produced worldwide [144]. In developing countries, the percentages of product losses are quite high due to a lack of appropriate technologies for postharvest storage of fruits and vegetables. The physiological, biochemical, and environmental changes promote the growth of postharvest pathogens that are the major causes of loss/damages in the supply chain. However, controlling postharvest destruction of fresh produce involves the application of synthetic antimicrobials, fungicides, and insecticides. Consumer concerns about the adverse effect of synthetic chemical residues on human health and environment, and the chances of the development of pathogen resistance, have led global scientific research towards the development of alternative strategies for the preservation of fresh produce [145].  
The application of a natural polymer (biopolymer)-based films and coatings on food surfaces have recently gained interest for the shelf-life extension of fresh produce due to their similar functions to those of conventional protection or synthetic packaging. Out of several natural polymers, the use of chitosan-based treatment at the postharvest stages has been considered to be a suitable alternative treatment to replace the use of synthetic chemicals [146]. Chitosan-based films and coatings have been reported to effectively extend quality and storability of food products in general, and of fresh agricultural produce in particular, due to its excellent natural antioxidant, antibacterial, and antifungal activities [147; 148; 149; 150].  
\begin{table}
\begin{tabular}{c c c c c} \hline \hline
**Application** & **Carrier/Additive** & **Type of the Study** & **Effective Against** & **References** \\ \hline Films & No & Laboratory & Bryozoan & [130] \\ \hline Films & No & Field & Micro-fouling & [131] \\ \hline Ultra-thin nanocoatings & No & Laboratory & Bacteria & [138] \\ \hline Films & Polyelectrolyte brushes & Laboratory and & Pathogens, & \\  & & field & micro-fouling and & [134] \\ \hline Paints & Silicon-polyurethane & Field & Micro-fouling and & [129] \\ \hline ZnO nanocomposites & ZnO nanoparticles & Laboratory & Micro-fouling & [86] \\ \hline ZnO nanocomposites & ZnO nanoparticles & Laboratory & Pathogenic bacteria & [85] \\  & & & and fungi & \\ \hline Silver nanocomposite films & Silver nanoparticles & Laboratory & Pathogenic bacteria & [132] \\ \hline Cellulose membranes & No & Laboratory & Pathogenic bacteria & [136] \\ \hline PAN-chitosan membranes & No & Laboratory & Bacteria & [139] \\ \hline Chitosan membranes & No & Laboratory & Pathogenic bacteria & [135] \\ \hline Forward osmosis & Graphene oxide & & & \\ membranes & nanosheets & Laboratory & Proteins & [137] \\ \hline PES membranes & Fe\({}_{3}\)O\({}_{4}\) nanoparticles & Laboratory & Proteins & [140] \\ \hline PES membranes & Silver nanoparticles & Laboratory & Proteins, bacteria & [141] \\ \hline \hline \end{tabular}
\end{table}
Table 3: Chitosan-based antifouling applications.