Convective Drying Kinetics of Corn Starch Biopolymer Films: Semi-Theoretical versus Fickian Modeling for Sustainable Packaging Process Design

Starch-based films are among the most promising biodegradable alternatives to petroleum-derived packaging, yet their strongly hydrophilic matrix makes drying a critical step that governs final film structure and properties. Despite this, drying modeling of biopolymer films remains far less explored than that of agricultural products, limiting the transport data needed for rational process design. This study compares semi-theoretical and diffusion-based models to describe the convective drying of corn starch films and to extract reliable transport parameters.

Films were cast from corn starch solutions plasticized with sorbitol and dried in a forced-air oven at 50, 60, 70, and 80 °C. Drying curves were fitted in MATLAB R2024a with the Newton, Page, and Modified Page models, while moisture diffusion was described by the analytical solution of Fick's second law for an infinite flat plate. Fit quality was assessed using R², RMSE, MAE, and SSE.

Higher temperatures markedly shortened drying time, and the effective moisture diffusivity increased overall from 1.54 × 10⁻⁸ to 4.47 × 10⁻⁸ m² s⁻¹. The Page model best described the kinetics, with R² above 0.98 at every temperature and clearly lower errors than the Newton model. The Arrhenius activation energy was 29.35 kJ mol⁻¹, indicating a moderate thermal barrier to moisture migration.

A combined semi-theoretical and Fickian approach accurately captured the drying of starch films and yielded transport parameters directly usable for the simulation and process design of biodegradable packaging manufacture.