Cross-linked films based on N-hydrophobic-O-hydrophilic chitosan derivatives: Preparation, properties and application in banana storage

Two kinds of N-hydrophobic-O-hydrophilic chitosan derivatives, N-2-hydroxypropyl-3-butyl ether-O-carboxymethyl chitosan (HBCC) and N-2-hydroxypropyl-3-(2-ethylhexyl glycidyl ether)-O-carboxymethyl chitosan (H2ECC) were synthesized and cross-linked with glutaraldehyde to prepare HBCC and H2ECC films. The properties of the cross-linked films, including microstructure, mechanical properties, water vapor permeability, swelling property, light transmission, wettability, thermal stability, antibacterial property, and biocompatibility were characterized. The uncross-linked HBCC and H2ECC films were used as controls. The results showed that the cross-linked films had tight structures, low water vapor permeability, strong water resistance, high UV light resistance, a slight decrease in visible light transmittance, and a small contact angle. The cross-linked films showed strong antibacterial activity against S. aureus and E. coli, non-toxicity to endothelial cells, and good biodegradability. Also, the cross-linked films can effectively prolong the fresh-keeping time of bananas by delaying the formation of soluble polysaccharides and malondialdehyde (MDA) in bananas. These results indicate that HBCC and H2ECC cross-linked films are potential biodegradable materials for fruit preservation.