Chemical and DNA authentication of taste variants of Gynostemma pentaphyllum herbal tea

• Published in: Food chemistry Vol. 128; no. 1; pp. 70 - 80
• Main Authors: Wu, Pui Kei, Tai, William C.S., Choi, Roy C.Y., Tsim, Karl W.K., Zhou, Hua, Liu, Xin, Jiang, Zhi-Hong, Hsiao, W.L. Wendy
• Format: Journal Article
• Language: English
• Published: Kidlington Elsevier Ltd 01.09.2011; Elsevier
• Subjects: Biological and medical sciences; Bitter taste; Food industries; Fundamental and applied biological sciences. Psychology; General aspects; Gynostemma pentaphyllum; Gypenoside; ITS sequence; Methods of analysis, processing and quality control, regulation, standards; Phylogeny; Taste variants; Taste variants; Gynostemma pentaphyllum; Gypenoside; ITS sequence; Phylogeny; Variant; Authentication; DNA; Quality control; Taste
• ISSN: 0308-8146; 1873-7072
• DOI: 10.1016/j.foodchem.2011.02.078

► The study involves authentication of taste variants of Gynostemma pentaphyllum (jiaogulan) herbal tea. ► No existing method is available to differentiate the bitter and sweet taste variants of jiaogulan. ► We find that the taste variants can be differentiated by HPLC-MS profiles of the plant saponins. ► Sequencing of the ribosomal DNA reveals a phylogenic distinction between the two variants. Gynostemma pentaphyllum Makino (Gp) was once used as a sweetener in Japan and is now widely consumed as an herbal tea worldwide for lowering cholesterol levels. Two taste variants, bitter and sweet, of Gp exist in the commercial market, but they cannot be differentiated morphologically nor by existing chemical analytical methods. This has been creating a problem in quality control of Gp products. In the present study, using HPLC-DAD and HPLC–ESI-MS analysis, we found that the Gp saponins, not flavonoids, from the sweet and bitter variants have distinctly different profiles. In addition, the two variants share only 69.01% homology in the ribosomal ITS-1 region, suggesting a phylogenic gap between these two variants. The combinations of chemical profiling and phylogenic analysis clearly confirm, for the first time, the distinction between these two taste variants. This information has direct application in the authentication and quality assessment of the various Gynostemma tea products.