Modelling the drying characteristics of ashwagandha (Withania somnifera) roots

Abstract

Ashwagandha (Withania somnifera) is a medicinal plant, the roots of which have been used in Indian traditional system of medicines, Ayurveda and Unani. Generally, roots in powder form are utilized in pharmaceuticals industries. In the present study, the drying behaviour of Ashwagandha roots was investigated by performing mathematical modelling. The roots were dried in shade and in tray dryer at three different temperatures (45, 50 and 55°C). The experimental results were fitted into six semi- theoretical thin layer drying mathematical models. From statistical parameters (coefficient of determination and root mean square error), the Modified Page Model represented the best fit for establishing the drying kinetics at three drying temperatures. Further, the effective moisture diffusivity ranges between 6.35 × 10-8 and 9.92 × 10-8 m2/s over the temperature range and drying occurs in the falling rate period. This study will be helpful in designing a drying system for ashwagandha.