Isothermal drying of plant-based food material: An approach using 2D polydimethylsiloxane (PDMS) micromodels

The aims of this study were to build PDMS micromodels that simulated plant-based food material, and use them to investigate the drying mechanisms at pore-scale, the drying front morphologies and the drying curves during the isothermal drying process. Micromodels were built using a modified photolithographic technique. Three normal pore size distribution functions were developed to simulate the plasmodesma, intercellular space, and cell wall. Micromodels were impregnated with a pyranine aqueous solution and placed on a balance illuminated with ultraviolet light. Isothermal drying was developed by natural convection (20 °C). Drying front morphologies displayed a hierarchical behavior in which pores with the largest diameter dried first. Drainage and surface evaporation sequences and internal evaporation controlled the drying of PDMS micromodels. The micromodels were useful to simulate plant-based food material and study isothermal drying of such porous media. The results led to the proposal of some drying mechanisms that were involved.