Optimization, Yield and Chemical Composition of Essential Oil from Kaempferia galanga L. Rhizome: Comparative Study with Microwave Assisted Extraction and Hydrodistillation

The microwave-assisted extraction (MAE) and the hydrodistillation (HD) were performed to extract the essential oil from the K. galanga dry rhizomes. The response surface method (RSM) and the analysis of variance (ANOVA) were deployed to optimize the process variables (microwave power, time and solid/liquid ratio). The aims of this research were to optimization of the process variables for MAE and to compare of the chemical compositions between HD and MAE. The microwave power, time and the interaction between time and solid/liquid ratio were the significant variables on the extraction yield of MAE. The highest yield of essential oil from HD and MAE that recovered on a dry weight basis were 0.52 and 0.92 % (w/w). The highest yield of MAE was derived by a power (800 W), time (28.38 min) and a solid/liquid ratio (100 g / 488.8 mL). The compositions were detected in the essential oil from HD and MAE at forty-five and sixtytwo contents. Ethyl (Z)-cinnamate, ethyl p-methoxycinnamate, eucalyptol and eicosane were the significant compositions that were detected in HD and MAE essential oils. The essential oil of K. galanga was rich in valuable compositions and the MAE is a potential extraction method for extracting the essential oil from K. galanga.