Influence of drying methods on the quality of Orthosiphon stamineus extract

Abstract

The interest in herbal products is tremendously increasing in recent years, probably due to their health promoting benefits. Drying is one of the important processes in herbal extract preparation. Therefore, this study evaluated the effects of drying methods on the quality of Orthosiphon stamineus (OS) extract. The OS extract was concentrated by a centrifugal concentrating system operated at three different modes (Infrared (IR), IR-Heat and Heat), vacuum evaporator (VE) and oven dryer. The phytochemical profiles of the dried extracts were analysed by LC-MS/MS. The oven-dried OS extract showed the highest yield (26.2%), followed by heat-dried, IR-heat-dried, IR-dried and VE-dried. The VE-dried extract showed the highest reduction of extract quality in term of its phytochemical content, particularly for the major compounds such as caffeic acid, eupatorin, eupatorin derivative, myricetin, rosmarinic acid, rutin and sinensetin. The drying kinetic for IR, heat and IR-heat methods were fitted well into Page model with R2>0.99. This research concluded that the selection of drying method is important because it will affect the phytochemical profile of the plant extract significantly.