Response surface methodology model to optimize concentration of agar, alginate and carrageenan for the improved properties of biopolymer film

The present study intended to develop improved biopolymer film from seaweed polysaccharides. The quantity optimization of polysaccharides for the composite film was sought by empirical response surface methodology. To achieve the goal, Box-Behnken model was applied to the concentration of three independent variables, viz. agar (1.0-2.0% w/v), alginate (1.0-2.0% w/v) and carrageenan (1.0-2.0% (w/v). The glycerol was used as a plasticizer and kept constant (25% w/w) for total solid mass. The overall desirability function fits with the quadratic model at 99.78% level of significance for the optimization of agar (1.99% w/v), alginate (1.45 w/v) and carrageenan (2.0% w/v) to reach minimum water vapor permeability and maximum tensile strength, elongation at break and puncture resistance. The absolute residual error (1.04-3.37%) of experimental and predicted response was also validated. Attenuated total reflection-Fourier transform infrared spectroscopy confirmed the interactions such as stretching at 2900 cm(-1) region corresponded to C-H stretching vibration and an intensity peak observed at 1200 cm(-1) of AAC film corresponded to sulfate ester groups. The shift in crystalline nature of composite film was confirmed by XRD. The 3D image of atomic force microscopy showed layer-by-layer assembly of intermolecules at 310-nm resolution, and the characterized smooth surface has more functional application. The carrageenan and agar are found to be more responsible for the film properties such as moisture content, thickness, whiteness index, transparency, swelling and erosion than alginate.