Formulation and process investigation of glycerol/starch suspensions for edible films production by tape casting

Potato starch-based films obtained by the tape-casting process for producing biodegradable food packages were studied. The stability of starch-in-water suspensions was preliminary investigated via the Turbiscan technique, as a function of the amount of starch, and the mixing regime adopted to suspend the system. The most stable samples, prepared with the addition of different fractions of plasticizer (glycerol), were investigated with transient viscosity tests upon cooling to mimic the real conditions of cooling ramp and shear rate occurring during the tape casting process. Thanks to these investigations, a few samples were selected for producing films at a constant fraction of starch while varying the amount of glycerol. The thermal behavior, microstructural investigation, FT-IR (Fourier-transform infrared) spectroscopy carried out on bioplastic films confirmed the plasticizing action of glycerol. On a smaller scale, atomic force microscopy highlighted a quite uniform and homogeneous surface of samples increased by the glycerol content.