Preparation and characterization of antibacterial chitosan nanocomposites loaded with cellulose/chitosan nanofibers and essential oils

Multi-component nanocomposites based on chitosan, cellulose/chitosan nanofibers, and essential oils were developed in this study through solution casting technique. Both surface and structural properties of the nanocomposites were characterized. Surface morphology results revealed that the chitosan nanofibers were more localized at the films' surface than the cellulose nanofibers, leading to enhanced hydrophobicity (contact angle = 95 degrees). Moreover, the essential oils were distributed as micrometer-scale oil domains at the films' surfaces, making them heterogeneous, leading to a much more hydrophilic character (contact angle = 30-36 degrees). X-ray diffraction results revealed the disrupting role of nanofibers on the crystalline structure of chitosan; however, upon the addition of essential oils, the crystalline network was less affected than the pure chitosan film. The enhanced stiffness of the films in the presence of nanofibers was demonstrated by dynamic mechanical analysis. In contrast, the addition of essential oils highly reduced the stiffness, making the films much more flexible, which could benefit food packaging applications. Antibacterial properties were highly increased in the presence of essential oils, and the barrier properties were also improved, especially by the use of chitosan nanofibers. In conclusion, the developed nanofiber-loaded chitosan films could be considered innovative packaging to promote food conservation.