Optimization of the Glycyrrhizic Acid Extraction from Licorice by Response Surface Methodology

This study aims to extract Glycyrrhizic Acid (GA) from Glycyrrhiza glabra L. (licorice) using a novel, high efficiency, and low-cost extraction method. Water was chosen as the proper solvent for the extraction process to eliminate the requirement of harmful and toxic solvents, prepare an environmentally friendly process, and reduce the costs. The effect of different process variables (extraction time, feed to solvent ratio, pH of extraction medium, and temperature) on the extraction, yield was investigated experimentally and statistical analysis using the RSM method was performed to analyze the effect of variables and obtain a proper model correlating the yield of extraction to variables. The obtained model was found successful in fitting the experimental results. It was found that all the four variables affect the yield of extraction significantly, and only the interaction between pH and extraction time was found important in increasing the GA% in the precipitate. The highest yield was achieved experimentally 54.9%, for the case with the extraction time of 17 h, feed to solvent ratio of 10 g/ml, pH of 10, and temperature of 60ºC.On the other hand, the optimum condition obtained by the model was found at extraction time of 10.12 h, feed to solvent ratio of 10.71 g/ml, pH of 9.8, and temperature of 119.7ºC.