UC Davis

Highlights Performance evaluation of a convective Drying Beads® (DB) zeolite-based system. Compared rice paddy drying with DB to 50°C conventional heated-air (HA) drying. Four distinct drying experiments were applied under two ambient conditions. DB significantly enhances the moisture removal rate by 84.3% in humid ambient conditions. DB and HA have a similar total milling yield, but DB has a 10% higher head rice yield in temperate ambient conditions. DB's exothermic reaction increases the drying rate by reducing humidity and rising temperature. Abstract. Desiccant-based drying has the potential to enhance rice quality and reduce energy consumption compared to conventional heated-air drying. This laboratory-scale study evaluated the performance and resultant quality of a convective Drying Beads® (DB) zeolite-based desiccant drying system to dry Calrose rice paddy (Oryza sativa). A rice paddy to DB ratio of 1:2 was compared to conventional 50°C heated-air drying (HA). Four distinct drying experiments, HA and DB, were performed under two controlled ambient temperature and relative humidity (RH) conditions. Conditions were representative of typical paddy drying environments: 22°C at 45% RH (HA1 and DB1) and 27°C at 80% RH (HA2 and DB2) conditions. All drying experiments aimed to achieve a wet basis moisture content (MC wb ) below 14%. Compared to their respective HA counterparts, the moisture removal rate (MRR) for DB1 was 9.3% lower, and DB2 was 84.3% higher. The head rice yield (HRY) and total milling yield (TMY), critical determinants of paddy grade and price, showed a 10% increase for DB1 and a 27.5% decrease for DB2. Despite these differences, TMY exceeded 71% for all drying experiments, and rice kernel color remained consistent throughout. This study showed that rice paddy DB drying is promising under temperate drying conditions. However, under humid drying conditions (DB2), improvements are necessary to enhance HRY, and the scalability to larger-scale operations warrants more investigation. Keywords: Dehydration, Food safety, Milling yield, Moisture removal, Paddy drying.