Modelling the effect of guar gum on physical, optical, barrier and mechanical properties of potato starch based composite film.

The composition of potato starch (PS) and guar gum (GG) based biodegradable composite film was optimised based on physical, optical, mechanical and barrier properties. The rotatable central composite design applying desirability function was used to assess the effect of PS (2.5-4.5%), GG (0.2-0.8%) and glycerol (15-35%). The optimisation was performed considering minimization of film solubility, opacity, yellowness index and water vapour permeability; and maximization tensile strength and percentage elongation at break. Viscosity of film forming solution; thickness, moisture content and whiteness index of the films were also evaluated. The optimum value of PS, GG and glycerol was 3.7%, 0.4% and 15% (of total solids), respectively. All the independent variables depicted significant effect on the responses (p < 0.05) except starch which did not exhibit any statistically significant effect on WVP. The structural characterisation of the optimised film was also analysed by FESEM and XRD which point to the semi-crystalline nature of the developed film.