Effect of internal variables on drying of Orthosiphon stamineus (Misai Kucing) plant

Abstract

Orthosiphon stamineus (misai kucing) is one of medical herbs that is well known in south East Asia. The drying process need to be improved for increasing the quality of the O. stamineus as the product used for medical purpose. The goal for this project is to investigate the effect of the internal variable on the drying of the O. stamineus plant. The leaves and stem of O. stamineus were dried using the hot air dryer at 50 °C. The drying curve for both part of plant took place in falling rate period. The moisture content for both part also decrease as time increase. The drying process was done until the equilibrium moistur content was achieved. The effect on the bioactive constituent were done by determined the antioxidant activities and total phenolic content. The antioxidant activities and total phenolic content were determined using 2,2-diphenyl-1-picrylhydrazyl (DPPH) and Folin-Ciocalteu method respectively. The antioxidant activities of fresh leaves (42.47%) are higher than stem (31.57%) for dry sample the leaves (83.39 %) also higher than stem (34.76%). The phenolic content for fresh leave (108.44 mg Gallic acid /g dry weight) also higher compare to the stem (58.00 mg Gallic acid /g dry weight). for the dry sample the leave (184.43 mg Gallic acid /g dry weight) also have higher TPC than stem (177.17 mg Gallic acid /g dry weight). Overall the dry samples give higher antioxidant activities and TPC for both plant parts. The different in structure for before and after drying for leave and stem part can be observed by using FESEMs