Quality assessment of liquorice combined with quantum fingerprint profiles and electrochemical activity

Liquorice, as a nutritional plant with a long histroy, is used in food and medical fields. In this study, we explored the quality consistent of liquorice from different locations by using multiple fingerprint profiles, including High Performance Liquid Chromatography (HPLC) and Fourier Transform Infrared Spectroscopy (FTIR). In addition, the average method of systematic quantified fingerprint method (AMSQFM) was presented to combine the chemical information of chromatography and spectral fingerprint. Macro qualitative similarity (Sm) and macro quantitative similarity (Pm) were used to assess the quality of 55 samples in terms of both qualitative and quantitative aspects. As a result, all the samples were well differentiated and classified into 6 grades. Additionally, partial least squares (PLS) model was used to evaluate the feasibility of quantizing glycyrrhizic acid (GLA) and liquiritin (LQT) by FT-IR spectral quantized fingerprint. The explanatory ability (R2Y) and prediction ability (Q2) of model were all greater than 0.9 and 0.5 respectively, the root mean square error of estimation (RMSEE) and root mean square error of prediction (RMSEP) were both less than 2.0. In the end, two characteristic parameters of electrochemistry (EC), oscillation life (tosc) and maximum amplitude (ΔEmax), were used to predict the reducibility of liquorice. Models were accurate and had good predictive abilities with the appropriate parameters, five active components in liquorice all exhibited certain reducing ability. In conclusion, this study provides a new idea for evaluating the quality and reduction ability of liquorice.