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Abstract: Licorice, the roots of Glycyrrhizia uralensis Fisch, is used as a medicinal herb and food additive in China. At present, the quality grading and authentication of licorice products is generally done by visual inspection, which is subjective and often biased. In this study, a rapid and nondestructive method for the classification of licorice samples according to their growing conditions, geographic areas and plant parts was developed using fiber optic diffuse reflectance near-infrared spectroscopy (FODR-NIR). With the use of multiplicative signal correlation (MSC) and Norris derivative filter, the differences of the NIR spectra among different licorice samples were enhanced even though the raw spectra were very similar. The results showed that the NIR spectra of the samples were moderately clustered in the principle component spaces, and pattern recognition technique of soft independent modeling of class analogy (SIMCA) provided satisfactory classification results. Additionally, a partial least square (PLS) method using HPLC data set as reference was constructed to predict the value of glycyrrhizic acid (GA) in licorice. The results showed that PLS models with both data normalization (DN) coupled with first derivative pretreatments, and MSC coupled with first derivative pretreatments provided acceptable results. [Copyright &y& Elsevier]

Abstract: Glycyrrhizic acid (GA) and licorice flavonoids (LF) are the two classes of bioactive components in licorice with known pharmacological effects. But long-term excessive intake of GA may cause sodium retention and hypertension. In this study, the performance and adsorption characteristics of four widely used macroporous resins for the separation of deglycyrrhizinated, flavonoids enriched licorice has been critically evaluated. The sorption and desorption properties of LF and GA on macroporous resins including XDA-1, LSA-10, D101 and LSA-20 have been compared. The adsorption capacity was found to depend strongly on the pH of the feed solution. XDA-1 offers much higher adsorption capacity for GA and LF than other resins, and its adsorption data fit the best to the Freundlich isotherm. XDA-1 also shows much higher adsorption affinity towards LF than that of GA based on calculated results from the measured adsorption isotherms. Dynamic adsorption and desorption experiments have been carried out on a XDA-1 resin packed column to obtain optimal parameters for separating GA and LF. An enriched LF extract (about 21.9% purity) free of GA, and an enriched GA extract with 66% purity can be separated from crude licorice extract in one run. [Copyright &y& Elsevier]

Multi-stage countercurrent extraction (MCE) technique has been developed for the extraction of glycyrrhizic acid (GA) from Glycyrrhiza uralensis Fisch, a particular plant species of licorice. The effects of extraction stage numbers, temperature, extraction time and solvent to licorice ratio on the extraction yield of GA were investigated in detail. The process conditions of MCE were optimized using orthogonal array experimental design (OAD) technique. Under optimum process conditions (five stages, 60 min extracting time for every stage, 60 °C temperature and 6 ml/g solvent to licorice ratio), the extraction efficiency of MCE has been compared with those of conventional techniques including batch single pot extraction (SPE), microwave-assisted extraction (MAE), ultrasonic extraction (USE), Soxhlet extraction (SHE) and room temperature extraction (RTE). Results show that the MCE process offers the highest GA extraction yield and considerable savings in time, energy and solvent consumption. [Copyright &y& Elsevier]