Quaternary solvent system for highly efficient separation and purification of glabridin by fractional extraction

•A quaternary solvent extraction system was explored to separate and purify glabridin.•The extraction system is green and simple without reactive extractant.•A mathematical model was established to simulate and optimize extraction process.•Residual rate is introduced to describe product purity and impurity content.•Glabridin with high purity and yield has been obtained continuously.