Effect of Ethanol Concentration in Ultrasound Assisted Extraction of Glycyrrhizic Acid from Licorice Root

The major active component in licorice is glycyrrhizic acid which is very useful in the pharmaceutical industry. In the present work, the extraction of glycyrrhizic acid in licorice is carried out in a stirred reactor as well as under indirect sonication in an ultrasonic bath. Batch extraction is carried out in a glass reactor of 150 mL capacity equipped with a six bladed glass turbine for agitation. Ultrasound assisted extraction has been carried out in a dual frequency ultrasound cleaning bath. The glycyrrhizic acid is analyzed using HPLC. Various process parameters such as solvent concentration, power, frequency of ultrasound, extraction temperature and solvent to solute ratio, which affect the extraction yield are optimized for both techniques. In ultrasound assisted extraction with final optimized conditions, i.e. 50% ethanol as solvent, 230 W power, 40:1 solvent to solute ratio, 30?C temperature and 40 kHz frequency, 95.69% extraction is obtained in 20 minutes, whereas in extraction using stirred reactor only 68% extraction is observed in 60 minutes. Kinetic of the extraction process is studied and volumetric mass transfer coefficients as well as theoretical yield for different process parameters are estimated.