Optimization of Solvent to Feed Ratios and Extraction Times of Green Tea Assisted by Microwave

An extraction method assisted by microwave is an extraction process that utilizes microwave energy to create molecular vibrations to produce friction which eventually generates heat in a short period of time. The heat formed will damage the cell wall or tissue material so that the solute can quickly exit from its solid. In this research, the ratios of solvent to feed and the extraction times to obtain optimum yield and tannin content of green tea were examined. The microwave-assisted extraction experiments were conducted by varying the ratio of solvent to feed (S/F) and the extraction times. The variations of S/F were 8, 12, 16, and 20 and the extraction times were 2, 4, 8, and 16 minutes. The extraction process was carried out at $75 \pm 5 ^{\circ }\mathrm {C}$ and the power input of 150 W. Thermal or mechanical treatments were not conducted before the tea leaf extraction processes were done. Microwaves were used for the extraction and drying of the tea extracts. The tea extract solution was concentrated by rotary evaporator. Analysis of tannin contents was performed by potassium permanganate titration method. This research resulted in the optimum S/F ratio of 14 and the optimum extraction time of 2.5 minutes.