Optimizing the Quality and Energy Drying of Temu Lawak (Curcuma xanthorrhiza Roxb.) Slices

Temu lawak or curcuma ( Curcuma xanthorrhiza Roxb.) is a popular medicinal plant. The dried slices of its rhizome –known as simplicia- are used for traditional medicine materials. This research aimed to determine the optimum drying conditions for maximum quality and minimum energy. The drying quality of temu lawak was based on the curcumin content and the energy drying was based on the exergy efficiency. The constraint is that the minimum curcumin content of simplicia is 4%, and the final moisture content is below 10%. Curcuma slices samples were dehydrated at temperatures of 50, 60, and 70 o C and 20%, 30%, and 40% RH. The study reported that lower drying air temperature and higher RH resulted in a higher quantity of curcumin in terms of temu lawak quality. The exergy analysis method assessed the energy drying at different temperatures and RH. The second law of thermodynamics was applied to determine the exergy efficiencies of the drying process. The study showed that lower drying air temperature and RH increases exergy efficiency. The optimum drying conditions of temu lawak with the highest quality were at a temperature of 50 o C and 38% RH meanwhile, the highest exergy efficiency was at a temperature of 50 o C and 20% RH. The optimum drying process conditions for both the highest curcumin content and exegetical efficiency were at a temperature of 50 o C and 21% RH.