Design and performance evaluation of a superabsorbent polymer-based dryer for medicinal plants

In this study, a superabsorbent polymer-based dryer (Polydryer) was constructed to dry rhizomes and fruits of various medicinal plants (turmeric, greater galangal, lesser galangal, ginger, Curcuma, finger root, and chili) into dried natural ingredients for the manufacture of drugs and medicines (simplisia). The Polydryer mainly consisted of a drying cabinet with three trays, a superabsorbent polymer hydrogel (polygel) cabinet with nine trays, and a blower. Ambient air at different airflow rates was utilized as the drying medium. A polygel based on acrylic acid monomers and cassava starch was employed to absorb the moisture carried by the air flow. Three Polydryer configurations, which included closed-loop or open-loop modes, were investigated to select the optimum dryer configuration. Drying of the rhizomes required 4-5 days to reach the maximum permissible moisture content in simplisia (<= 12%). The simplisia exhibited low color change and less structural damage than the commercial simplisia. Practical applications Superabsorbent polymer materials have been known to have outstanding moisture absorption properties. Upon storing in an ambient atmosphere, the material tends to swell in the presence of moisture. These promising properties prompt the development of a superabsorbent polymer-based dryer. The ability of the superabsorbent polymer to absorb moisture in the ambient atmosphere enables a low-temperature operation, retaining material structure and maintaining bioactive compounds in the medicinal plant materials. This study revealed that drying medicinal plants using the Polydryer is time-effective compared with conventional drying techniques, with less structural damage to the materials. This technology is simple, cost-effective, energy-efficient, and highly sustainable for the drying process of medicinal plants that can be implemented in agricultural and pharmaceutical industries. This study is the first to report the application of superabsorbent polymer in the drying process of medicinal plants.