Stable isotopic and elemental characteristics with chemometrics for the geographical origin authentication of Dendrobium officinale at two spatial scales

Abstract

Dendrobium officinale Kimura et Migo (D. officinale) is a healthy tea with protected designation of origin labels, which requires of authenticating its geographical origin. Stable isotope ratios of 87Sr/86Sr, δ13C, δ15N, δ2H, and δ18O and 24 element contents of D. officinale in 379 samples from 11 sites in six provinces were compared at two spatial scales: regional scale among the six provinces, and local scale among six sites within Zhejiang province. 87Sr/86Sr, δ13C, and Ca were significantly different only at regional scale, while Fe was different only at the local scale. Combined with chemometric methods such as Linear Discriminant Analysis and Random Forest high accuracies were obtained for the geographical origin authentication at both regional (100%) and local scale (98.81%). Moreover, ranks of variable importance differed between the regional and local scale discrimination. The top ten important variables at the regional scale were Zn, Sr, δ2H, Ba, Mn, δ15N, Cu, 87Sr/86Sr, Nd, Rb, while those at the local scale were Na, δ15N, Cu, δ2H, Zn, Ni, La, Rb, Nd, and Pb. This study established a stable isotope and element fingerprints dataset of D. officinale, provided potential authenticating methods, and revealed different variable importance ranks for the two scales.