Low-temperature process for green tea drying using zeolite adsorption integrated fluidized bed dryer

This work studied the optimization of low-temperature drying by using a laboratory scale and applied it on the pilot plant scale of fluidized bed dryer integrated with zeolite adsorption. The drying time was observed regarding the airflow rate, temperature and zeolite-tea leave ratio. The green tea leaves moisture content was specified gravimetrically until constant weight can be obtained. Applying 70°C as the drying temperature, the green tea leave is secure for a faster drying rate and can be avoided from the catechin epimerization and thermal degradation. Applying 0.40 m/s as airflow rate can remove the water surface faster than 0.50 m/s of airflow rate, although it needs a longer time to drag out the inner moisture content of the solid. The pilot-plant scale required longer time (40 minutes) on the first falling rate period than laboratory scale (30 minutes), although it gave faster second falling rate period at the same airflow rate (0.50 m/s), temperature (70° C) and zeolite-tea leave ratio (25:75).