Thin layer drying of black tea

This paper describes the experiments used to determine the kinetics of tea drying. New thin layer drying apparatus was designed and built to measure the very high rates of drying found at the start of drying, and the results show that the Lewis equation satisfies. The drying rate constant proved to be a linear function of temperature and airflow rate, indicating that tea drying is not only diffusion limited but also a function of convection. The results were validated on independent experiments. (C) 1999 Silsoe Research Institute.