Development of a biodegradable composite film from chitosan, agar and glycerol based on optimization process by response surface methodology

Abstract

The aim of the study has been to develop a biodegradable film from marine polysaccharides. The optimization of polysaccharides quantity for the composite film was sought by empirical response surface methodology. The Box–Behnken Model Design was applied to optimize the concentration of chitosan (1.0-2.0% (w/v)), agar (1.0- 2.0% (w/v)) and glycerol (0.1-0.5% (w/v)) as independent variables to achieve the goal. The overall desirability function fits with the quadratic model (0.862043) at a significant level (p < 0.05) for the optimum concentration of chitosan (1.5% (w/v)), agar (2.0% (w/v)) and glycerol (0.41% (w/v)) to obtain the minimum water vapor permeability (7.25 10-10g m m-2 Pa-1 s-1) and maximum tensile strength (12.21 Ma P), elongation at break (7.32%) and puncture resistance (16.18 N) in the optimized composite film. The absolute residual errors of experimental and predicted responses were between 1.24 and 3.56% acceptable levels. Attenuated total reflection–Fourier transform infrared spectroscopy confirmed the intermolecular non-covalent hydrogen bond between the hydroxyl groups of agar and glycerol with the amino group of chitosan. 3D atomic force microscopy images revealed that the chitosan, agar and glycerol film has layer-by-layer smooth surface properties due to homogenous interaction among the polysaccharides; this provides the film with good mechanical properties and with functional application. Chitosan was found to be responsible for the lower level of water vapor permeability and higher puncture resistance of the film. Tensile strength and elongation at break were influenced by agar and glycerol. The whiteness of the film was negatively affected with the concentration of chitosan.