Effect of deacetylation degree on properties of Chitosan films using electrostatic spraying technique

Chitosan (CH) films at 4.4 kDa with different deacetylation degree (DD, 81.0, 88.1 and 95.2%) and concentration (0.9, 1.2 and 1.5%) were prepared using electrostatic spraying (ES) system. The effects of DD and concentration on film-forming solution properties, ES-atomization effects, and film performances were investigated. Results indicated that surface tension and viscosity of CH solution declined with the increase of DD, while solution conductivity displayed the opposite trend. The spray angles of film-forming solution during ES were in the range of 10.6-14.2 degrees, and the average median diameters of droplet sizes were all ranged from 6.4 to 13.9 gm. The spray angle and droplet size generally reduced with increasing DD, and thus more complete, rougher and more crystalline microstructures of CH films were observed by SEM, AFM and XRD. CH films at 88.1 and 95.2% DD had better water barrier property and tensile strength. In addition, antibacterial capacities of CH films against L.innocua and K con were enhanced with DD. The results could provide guidance on the application of ES technology to improve the commercial food safety such as, fruits, vegetables, poultry, meat, and seafood.