云南普洱茶产地微量元素的指纹溯源

The Application of Multi-Element Anlysis to Determine the Geographical Origin of Pu-erh Tea

摘要:

通过普洱茶特征元素筛选，结合土壤微量元素因子，建立高效准确普洱茶产地溯源模型。采用等离子发射光谱质谱法测定来源于云南普洱茶三大产区（西双版纳、普洱和临沧）的种植土壤和茶叶成品中的14种微量元素（Mn、Fe、Li、Be、Ti、Co、Ni、Mo、Cu、Zn、Pb、Cr、Cd、As、Se）和16种稀土元素（La、Ce、Pr、Sm、Eu、Gd、Tb、Dy、Ho、Er、Tm、Yb、Lu、Nd、Sc、Y）的含量，对其进行了方差分析、相关性分析、主成分分析和判别分析（逐步线性判别）。对不同产区的普洱茶微量元素和稀土元素分析，结合同种元素在土壤中的相关性，筛选出La、Ce、Pr、Sm和Se 5种元素作为判别普洱茶产地判别指标，对样品的初始正确识别率为：89.3%，交叉验证识别率为：89.3%。普洱茶中微量元素与稀土元素组成受到土壤的影响，在各自产地间形成各自的指纹特征，可以用于鉴别普洱茶的产地溯源。

Abstract:

In order to establish prediction model for identifying the different regions of Pu-erh tea origin, it is demanded to determine the geographical origin of tea. Contents of fourteen trace elements (Mn, Fe, Li, Be, Ti, Co, Ni, Mo, Cu, Zn, Pb, Cr, Cd, As, Se), and sixteen rare earth elements (La, Ce, Pr, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, Nd、Sc, Y) in tea and soil samples from three major producing Pu-erh tea regions including Xi-shuangbanna, Pu-er and Lincan City, were analyzed by inductively coupled plasma mass spectrometry (ICP-MS). The multivariate statistical methods such as variation analysis, correlation analysis, principle component analysis (PCA) and discriminant analysis were used for data analysis. The research showed that the mineral element fingerprints had distinct geographical features. The method of PCA could be used to classify the geographical origin of tea from different origins but with a cross in the scatter plot. Furthermore, five key variables (La、Ce、Pr、Sm and Se) were identified by stepwise discriminant analysis to develop the discriminant models by which 94.6% correct classification and 89.3% cross validation were achieved. The trace elements and rare earth elements of Pu-erh tea are affected by soil, which can form their own fingerprint characteristics in their habitats and regions and can be used to identify the origin of Pu-erh tea.