In this study, the effects of temperature on drying kinetics and eurycomanone content of
Eurycoma longifolia roots were investigated to determine the optimum temperature for
drying of this herb. The roots were subjected to drying temperatures of 40, 50, 60 and 70°
C. The drying kinetics data indicated that the drying rate increased with increase in
temperature but decreased with time. The drying process took place in the falling rate
period. Three established thin layer drying models include Page, Midili and Logarithmic
were employed to describe the drying process. The Midili model was found as the best
fitting model in representing the process. The quality of the products was evaluated by
comparing the content of its active compound, eurycomanone, quantified using an ultra
performance liquid chromatography (UPLC). The fastest drying process was achieved at
70°C, but UPLC results showed that the product suffered at 18% reduction in
eurycomanone content as compared to the control. Based on the findings of this work, the
optimum drying temperature for E. longifolia roots is 60°C.