Developing multicomponent edible films based on chitosan, hybrid of essential oils, and nanofibers: Study on physicochemical and antibacterial properties

Abstract

Plastic waste is one of the major threats to the environment, and an urgent need to replace synthetic plastics with sustainable materials is progressively growing. Herein, sustainable films based on chitosan, Satureja, and Thyme essential oils (EOs), and chitosan nanofibers (NF) were developed for the first time. To this end, 1% (w/w) of EOs and 2 wt% of NF were incorporated into the chitosan solution. Despite the very similar chemical structure of carvacrol and thymol, which are the major constituents of Satureja and Thyme EOs, respectively, they imposed notably different effects on the physicochemical properties of chitosan films. Thyme EO was more efficient at establishing hydrogen bonds with chitosan. The disruptive effect of EOs on the crystalline network of chitosan was demonstrated through X-ray diffraction analysis. Satureja and Thyme EOs decreased and increased the barrier property of the chitosan films against water vapor, respectively. However, the barrier property was greatly improved in the presence of chitosan nanofibers. Satureja EO exhibited a more efficient antibacterial property against E. coli rather than Thyme EO. The fruits and vegetables, coated by the chitosan/EO/NF system, were less perished as compared with the control and chitosan-coated samples indicating the promising potential of the developed system to be used as edible and sustainable films and coatings due to their enhanced antibacterial and barrier properties.

Keywords: Antibacterial; Chitosan; Essential oil; Films; Nanofiber.