Estimation of glycyrrhizic acid content using canopy spectroscopy in visible-shortwave infrared region

Chinese licorice, the root of Glycyrrhiza uralensis Fisch, is one of the more widely used herbal drugs in China. Glycyrrhizic acid (GA), the one of the main active ingredients in G. uralensis, is generally used as an indicator to assess the quality of G. uralensis. At present, the methods of determining GA content are laborious and time consuming and cannot be applied to remotely sensed technology. In this study, we developed methods using canopy spectral data in visible-shortwave infrared region to qualitatively classify G. uralensis samples and to quantitatively predict the GA content by a partial least square (PLS) model. The results showed that our methods provided acceptable results and implied the ability of determining GA content from remote sensing data.