Response surface methodology for optimisation of glycyrrhizic acid extraction from Glycyrrhiza glabra in the aqueous two-phase system

ABSTRACT Glycyrrhizic acid (GA) is a natural sweetener obtained from Licorice (Glycyrrhiza glabra) and has numerous biological activities. In the present study, partitioning of GA in the polyethylene glycol (PEG)-salt aqueous two-phase system (ATPS) was optimised using the central composite design of response surface methodology (RSM). Effects of different operational parameters, such as salt concentration, pH, molecular weight of PEG, and concentration were studied to recover GA. The RSM predicted optimised conditions comprised 15.65% (w/v) of PEG 4000, 19.69% (w/v) of Sodium citrate and pH 8.0, yielding 28.39 mg/g GA. The close resemblance of the predicted and experimental yield of GA outlined the successful validation of the response model. In addition, the ATPS method offered lower energy, process time, cost economics and solvent consumption over conventional Soxhlet extraction. GRAPHICAL ABSTRACT