不同海拔区间白茶化学元素特征分析及产地判别

Characteristic Analysis of Chemical Elements and Identification of Production Regions of White Tea from Different Altitudes Intervals

为探究矿质元素和稀土元素在小尺度区域内白茶产地鉴别的可行性,本研究以政和县内不同海拔区间生产的白茶为对象,采用电感耦合等离子质谱法(ICP-MS)测定矿质元素和稀土元素含量,并结合化学计量学工具,筛选出指标元素,构建不同海拔白茶判别模型。结果表明,政和县相对较低海拔区间福安大白茶(LWT)中K、Ca、Mg、Mn的含量极显著(P<0.01)或显著(P<0.05)高于相对较高海拔区间福安大白茶(HWT),LWT中的Na、As、Cd、Sn、Se含量极显著低于HWT(P<0.01);LWT中的Ce、Y、La、Lu、Pr、Sm、Tb、Tm、Nd含量极显著(P<0.01)或显著(P<0.05)低于HWT。采用逐步判别分析方法,筛选出Ca、K、Cd、Pb和Sn 5种特征矿质元素,其整体初始和交叉验证的判别准确率分别为91.7%和88.3%;筛选出Eu和Tb 2种特征稀土元素,其整体初始和交叉验证的判别准确率均为91.7%;7种特征化学元素整体初始和交叉验证的判别准确率分别为98.3%和96.7%。正交偏最小二乘判别分析的预测指数顺序为16种矿质元素(0.619)<5种特征矿质元素(0.678)<15种稀土元素(0.682)<2种特征稀土元素(0.734)<7种特征化学元素(0.807),以7种特征化学元素为指标时最佳。联合特征矿质元素和特征稀土元素,可以对小尺度区域内不同海拔区间生产的白茶进行有效的产地判别,可作为产地溯源的有效方法。本研究为福建省名特茶叶中化学元素数据库建立及产地判别提供了科学依据。

This study aimed to investigate the feasibility of mineral elements and rare earth elements in identification of white tea origin.The mineral elements and rare earth elements of white tea produced in Zhenghe county at different altitudes were analyzed using inductive plasma coupled with mass spectrometry and chemometrics tools to screen the index elements and construct the discriminant models.The contents of K,Ca,Mg and Mn in Low altitude intervals of Fu’an big white tea(LWT)were extremely significantly(P<0.01)or significantly(P<0.05)higher than that of the high altitude intervals of Fu’an big white tea(HWT).However,the contents of Na,As,Cd,Sn,Se in LWT were extremely significantly lower than that of HWT(P<0.01),Ce,Y,La,Lu,Pr,Sm,Tb,Tm and Nd in LWT were extremely significantly(P<0.01)or significantly(P<0.05)lower than that of HWT.Five characteristic mineral elements,including Ca,K,Cd,Pb and Sn,were selected by step discriminant analysis.The overall discriminant accuracy of initial and cross verification was 91.7%and 88.3%,respectively.Two rare earth elements,including Eu and Tb,were screened,and the discriminant accuracy of both the overall initial and cross validation was 91.7%,respectively.The overall initial and cross validation discriminant accuracy of the seven special chemical elements were 98.3%and 96.7%,respectively.The discriminant prediction index value analyzed by orthogonal partial least squares discriminant analysis followed the order of 16 mineral elements(0.619)<5 characteristic mineral elements(0.678)<15 rare earth elements(0.682)<2 characteristic rare earth elements(0.734)<7 characteristic chemical elements(0.807).When seven characteristic chemical elements were used as indexes,the LWT and HWT had a better identification effect.Therefore,combination of mineral elements and rare earth elements was effective in the identification of white tea produced in small scale areas of different altitudes.This study provides a scientific basis for the establishment of chemical element database and the identification of origin tracing of special tea in Fujian Province.