Effect of natural deep eutectic solvent and chitosan nanoparticles on physicochemical properties of locust bean gum films

Novel bio-based films containing Locust Bean Gum (LBG) and Chitosan (CH) or Chitosan nanoparticles (CHNPs)/natural deep eutectic solvents (NADES) were investigated. The films with different LBG and CH-NPs w/w ratios in the absence or in the presence of NADES plasticizer were prepared by a semi-continuous knife-coating process. The detailed characterization of the films confirmed their transparency, uniformity, and homogeneity, without cracks or pores. FTIR spectra confirmed physical entanglements and miscibility between film components and suggested the occurrence of interaction between CH and LBG components. The mechanical, optical, rheological, thermal and water barrier properties of the new films were also evaluated. It was found that addition of CH-NPs reduced the apparent viscosity of LBG solution, and that the presence of NADES provided more flexible films with less mechanical and barrier resistance. In contrast, the addition of CH-NPs to the LBG solution provided films with enhancement of tensile strength and Young's modulus and a slight increase in water vapour permeability.