Combining stable C, N, O, H, Sr isotope and multi-element with chemometrics for identifying the geographical origins and farming patterns of Huangjing herb

Huangjing (Polygonati Rhizoma) is a high-value homology of medicine and food in China, for which the geographical origins (i.e., geoherbalism) and farming patterns (natural or farmed) are decisive in its functions and selling price. In this study, five stable isotope ratios (delta 13C, delta 15N, delta 18O, delta 2H, and 87Sr/86Sr) and 48 multielement signatures of 238 Huangjing samples collected from seven main production areas in China were analyzed together for origin traceability and farming authentication purposes. An analysis of variance (ANOVA) for each variable revealed that delta 18O, delta 2H, 87Sr/86Sr, Fe, and rare earth elements were significantly different among origins. The orthogonal partial least squares discriminant analysis (OPLS-DA) modeling of all variables indicated that K, Ca, Mg, Fe, and Mn were the most important variables (VIP > 1) for identifying Qingyang Huangjing protected geographical indication (PGI) from those of other origins, and discriminant accuracy reached 100 %. Moreover, ANOVA and OPLS-DA demonstrated that delta 15N, K, Ca, and Mg were the elements that effectively distinguished natural and farmed Huangjing. Therefore, the strategy may be an important alternative tool for authenticity management, which is significant for combating origin mislabeling and the fraudulent conducts of Huangjing products.

Automated summary

This study analyzed stable isotope ratios and multi-element signatures of Huangjing samples from different production areas in China, identifying key elements for origin traceability and farming authentication. Elements such as potassium, calcium, and magnesium were found to be important for distinguishing geographical indication and natural farming Huangjing from others.