Blends of gellan gum/xanthan gum/zinc oxide based nanocomposites for packaging application: Rheological and antimicrobial properties

Gellan (G) and xanthan gum (X) based nanocomposites containing zinc oxide (Z) nanoparticles (NPs) were fabricated. The effect of zinc oxide on the structure, morphology, and rheological properties of GX composite films were studied. The prepared nanocomposites exhibited shear thinning behavior and a decrease in viscosity when the shear rate was increased. The storage and loss modulus of the GXZ nanocomposites increased with increased zinc oxide percentage and frequency. There was a decrease in complex viscosity at high frequency. The tensile strength (22.1-35.5 MPa), thermal stability (T-5%-82.5-96.2 degrees C), and glass transition temperature (69.9-74.8 degrees C) of the nanocomposite films increased with the addition of zinc oxide NPs. The results showed that the incorporation of zinc oxide NPs increased the contact angle (54.1-60.8 degrees) and decreased the water vapor permeability (3.83-2.31 x 10(-9) g/m(2) Pas) of the nanocomposites, indicating a decrease in hydrophilicity. The GXZ nanocomposite films exhibited higher ultra-violet light shielding, and superior thermal and water barrier properties than the GX composite film. Based on these results, GXZ composite films could make a beneficial contribution to food and pharmaceutical packaging applications. (C) 2019 Published by Elsevier B.V.