# Electrospinning of Chitosan for Antibacterial Applications--Current Trends
## 7 Application Fields of Electrospun Chitosan Nanofibers and Chitosan Derivatives
### Food Storage
#### 7.3.1 Fruit Freshness  
Due to its proven antibacterial preserving properties and biocompatibility, chitosan has been used in food containers to extend the shelf life of fruits and meat and to keep them as fresh as possible during long transportation distances, in storage rooms, and on shelves. The disadvantage of coating fruit with a chitosan wet film is that it absorbs moisture from the air, providing a good environment for bacterial growth on the fruit's surface. Constant drying is, therefore, required through wet coating applications, which causes moisture loss and damage to the fruit. The alternative solution would be to produce a protective nanofibrous membrane via electrospinning of chitosan blend solutions. For this purpose, a solution of a chitosan derivative, carboxymethylchitosan (CMCS), and PEO was prepared for electrospinning of a nanocomposite membrane to explore its effectiveness in maintaining strawberry freshness. A reference sample covered with a commercial wrap was tested for fruit weight loss and degree of rotting and compared to the nanofibrous package, whose antibacterial activity, porosity, hydrophilicity, and intermolecular structure were also assessed [187]. As it is difficult to form chitosan-derived fibers using electrostatic fields, in order to optimize the electrospinning process, water-soluble non-toxic PEO was added to the CMCS solution, as this facilitates polyol binding and the solubility of the CMCS. With concentrations in the range of 2.5-7.5 wt% for each CMCS and PEO solution, clear Taylor cone building was observed. The composite nanofibers had an average diameter of 290 nm. The packaging film consisted of an electrospun membrane with a ratio of 1:12 PEO/CMCS, because the viscosity of that mixture was the most suitable for the formation of a complete electrospun film with homogeneous nanofibers and uniform micropore size. This ensured even breathability, promoting the exchange of air through the packaging film with regulated concentrations of O\({}_{2}\) and CO\({}_{2}\) for an optimum fruit storage environment. With infrared spectroscopy, characteristic peaks indicated no change in the structure of electrospun pure CMCS powder compared to CMCS/PEO composite nanofibers. To test the antibacterial effect of the CMCS/PEO nanofibrous membrane against the most spoiling bacteria found in food, _E. coli_ and _S. aureus_ were placed on two control non-woven filters and two electrospun membranes separately. The antibacterial rings clearly formed around the two bacteria strains in each of the samples including the composite material and were absent in the control samples, which confirmed the inhibitory effect of CMCS/PEO. Afterward, to test its compatibility with the fruit storage industry, four groups of similar strawberries were prepared. The first control sample was completely exposed to air, the second one was wrapped with a conventional polyethylene (PE) film, the third group was coated with a protective layer of CMCS/PEO solution with the film being dried, and the last group was covered with the electrospun CMCS/PEO membrane. All groups were placed at the same room temperature and their weights were measured multiple times. After 6 days, the unprotected control group experienced a fast weight loss and degradation due to the increase in fruit metabolism. The second covered group did not exhibit any bacteriostatic effect, as mildew was spotted on the surface, although its weight loss was slower than the coated group 3, as the latter exhibited surface browning and shrinkage but without any rotting effect. This demonstrates that the PE cover was very compact, not letting any air enter, seeing as it could control the fruit dehydration but not rotting, whereas the CMCS/PEO protective coating prevented the bacterial attack. As it was exposed to air moisture on the fruit's surface, however, it caused the oxidative degradation of ascorbic acid and internal water loss.