In this study, inulin (INU) extracted from burdock root was utilized as a new film base material and combined with chitosan (CHI) to prepare composite films. Oregano and thyme essential oils (OT) were incorporated into the INU-CHI film to confer the films with bioactivities. The physical and optical properties as well as antioxidant and antimicrobial activities of the films were evaluated. INU film alone showed poor physical properties. In contrast, the compatibility of INU and CHI demonstrated by the changes in attenuated total reflectance-Fourier transformation infrared spectrum of the INU-CHI film increased tensile strength and elongation at break of the INU film by 8.2- and 3.9-fold, respectively. In addition, water vapor permeability, water solubility, and moisture content of the films decreased proportionally with increasing OT concentration in the INU-CHI film. Incorporation of OT also increased the opacity of a and b values and decreased the L value of the INU-CHI films. All INU-CHI films containing OT exhibited antioxidant and antimicrobial properties. Particularly, the INU-CHI film with 2.0% OT exhibited the highest 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulphonic acid), 2,2-diphenyl-1-picrylhydrazyl radical scavenging, and antimicrobial activities against four pathogens. Thus, the INU-CHI film containing OT developed in this study might be utilized as an active packaging material in the food industry.
Keywords: burdock root; chitosan; edible film; essential oil; inulin.