Discrimination between Zingiberis Rhizoma Praeparatum and carbonised ginger by colour measurement and fingerprint analysis.

INTRODUCTION

Zingiberis Rhizoma (ZR) has been used as a traditional Chinese herb and culinary food for thousands of years. Its two processed products, Zingiberis Rhizoma Praeparatum (ZRP) and carbonised ginger (CG), possess different therapeutic effects.

OBJECTIVES

To establish an objective and comprehensive method to differentiate ZRP from CG and to evaluate their qualities.

METHODOLOGY

Colour values of ZRP and CG were tested to establish the colour models by spectrophotometry. Moreover, high-performance liquid chromatography (HPLC) was developed for fingerprint and quantitative analysis, and chemometric approaches were applied to discriminate between ZRP and CG. Finally, Spearman's correlation analysis was performed to investigate the relationship between the colour values and the peak areas of the common chemical compositions.

RESULTS

Colour reference ranges of colour parameters and mathematical functions were built to distinguish ZRP from CG. In fingerprint analysis, 26 common peaks were detected in these two processed products, among which 6-gingerol, 8-gingerol, 6-shogaol, 10-gingerol, 8-shogaol and 10-shogaol were identified. Meanwhile, ZRP could be differentiated from CG by chemometrics analysis. In addition, the correlation between colour parameters and common peak areas was found and the contents of 6-gingerol, 8-gingerol, 6-shogaol, 10-gingerol, and 8-shogaol were determined simultaneously.

CONCLUSIONS

An objective approach of colour measurement, HPLC fingerprint coupled with chemometrics analysis and quantitative assessment could be applied to discriminate ZRP from CG and evaluate the qualities of ZRP and CG rapidly.