In this study, the drying behavior of cassava starch-based edible films was investigated. Formulations were elaborated with rebaudioside A, glycerol, and low concentrations (0.5, 2, and 4%, w/w) of yerba mate (Ilex paraguariensis St. Hil.) extract (YM%). Physicochemical properties (pH, apparent viscosity, and density) and film-forming capacity (dip-coating method) were evaluated at 25°C. Films were casted by drying and mathematically described using the Henderson and Pabis thin-layer model. Effective moisture diffusion coefficients (D_eff) were determined using theoretical film thicknesses evaluated at the critical moisture content. The D_eff dependency on temperature and YM% was analyzed using an Arrhenius-type model. Based on the results, as YM% increased, values of pH, and apparent viscosity decreased. Low YM% increased the drying rates and the values of D_eff of cassava starch-based edible films elaborated with rebaudioside A as a sweetener and bioactive compound, obtaining the highest values at 4% (w/w) and 70°C.

Novelty impact statement

The optimization and control of the drying process are important to produce coated foods with high-quality and nutritional value in the industry. Yerba mate extract powder added to cassava starch-based formulations at low concentrations (<5%, w/w) is suitable for obtaining edible films and coatings with higher drying rates and effective moisture diffusion coefficients that control film casting due to the better hydrophobicity and plasticizing effect. This information could be useful to manufacture new film-forming fluids with bioactive compounds (e.g., rebaudioside A), such as alternative bio-packages that allow to replace the disposable composite synthetic plastic containers, and products for people with special diet requirements due to its low or sugar-free nature.