Focused Microwave-Assisted Extraction Versus Conventional Solvent Extraction of Glycyrrhizic Acid from Licorice Root

Abstract

Conventional solvent extraction and microwave-assisted techniques were used to extract glycyrrhizic acid (GA) from licorice root, using different solvents including polar and non-polar solvents. For both extraction techniques, higher glycyrrhizic acid yields were consistently obtained with water than with other solvents from the same samples. Solubility of glycyrrhizic acid or salts in water is the major cause of this observation. For microwave assisted extraction (MAE) with water, glycyrrhizic acid yield increased to 3.10% in 7min. Similar observations were made with conventional solvent extraction, glycyrrhizic acid yield was raised to 3.12% in 90min. The extracts were analyzed by high-performance liquid chromatography equipped with an ultraviolet detector. The kinetic studies were supplemented by scanning electron micrographs (SEM), and a mechanism based on the mass transfer between the solvents and matrix had been proposed to account for the acceleration extraction made with MAE.