Optimization of microwave drying of Aquilaria malaccensis leaves

In this study, the operating condition of microwave drying of Aquilaria malaccensis leaves was optimized by Response Surface Methodology using existing data from the previous study. It is found that the extract from the A. malaccensis leaves have a promising potential in treating diabetic patients because of its anti-diabetic properties known as α-amylase inhibitor. In order to retain the valuable medicinal contents, the leaves were preserved using microwave drying prior to extraction process. Therefore, operating parameters of the microwave drying, such as power output and drying time, must to be optimized to obtain a better quality dried product and maximum αamylase inhibitor activity. A face-centered Central Composite Design in the Design Expert Version 7.1.3 software program was employed to optimize the microwave drying process conditions. At the end of this study, the optimum operating conditions for the microwave drying process were obtained. The optimized operating conditions selected by the software for the microwave drying process are at power input of 150W and drying time of 9.35 minutes in which gave the desired lowest moisture content of 0.158538 kg H2O/kg dry solids. The dried leaves obtained from these optimized conditions would result a maximum percentage of α-amylase inhibition of 96.77% with a combination of using ethanol solvent during the extraction process. The results from this study showed that a high percentage of α-amylase inhibition activity can be obtained from the extracts of Aquiliria malaccensis leaves that was preserved at optimized microwave drying conditions as stated here.