山东茶叶轻稳定同位素和矿物元素特征与产地识别化学计量学分析

Light Stable Isotope and Mineral Element Characteristics and Geographical Discriminate Analysis With Chemometrics of Shandong Tea

为保护我国山东地理标志茶叶,通过元素分析仪-稳定同位素比率质谱(EA-IRMS)和电感耦合等离子体质谱(ICP-MS)测定轻稳定同位素比值、矿物元素含量或同位素比进行特征挖掘及探讨,并采用化学计量学方法对山东不同产地的绿茶进行识别分析研究。结果表明,山东各产地茶叶中δ13C、δ2H、δ18O无显著差异,但δ2H和δ18O表现出沿海地区高于沿海内陆地区的规律,且δ18O与δ2H变化呈较高的线性相关性(R2=0. 817 5);崂山产地的δ15N值较大,与其他产地间差异显著;临沂-泰安产地与崂山、胶南和日照三地地质条件不同,使得茶叶中某些矿物元素特征表现出空间分布上的差异。利用偏最小二乘判别分析分别对崂山、日照与山东其他产地建立茶叶识别模型,总体判别准确度分别为97. 8%(崂山模型)和96. 4%(日照模型),能够有效识别2个产地的茶叶。本研究结果可为茶叶中稳定同位素、矿物元素特征与产地环境的关联性分析,地理尺度更小的茶叶产地判别和地理标志产品保护提供研究思路。

In order to protect Shandong tea with protected Designation of Origin,the characteristics of light stable isotope,mineral element content or isotope ratio of green tea samples were determined by elemental analyzer-stable isotope ratio mass spectrometry(EA-IRMS)and inductively coupled plasma-mass spectrometry(ICP-MS),and the origin identification were discussed by chemometrics.The results showed that the difference ofδ13 C,δ2 H,andδ18 O in Shandong tea was not significant;δ2 H andδ18 O of littoral were higher than that of inland near littoral,andδ18 O was linearly correlated withδ2 H(R2=0.8175);δ15 N was larger in Laoshan origin which was significantly different with that of other origins.As for geological condition of Linyi-Tai’an region were different from those of Laoshan,Jiaonan and Rizhao,which makessome elementsappear spatial distribution.PLS-DA was used to establish the models of tea in Laoshan and Rizhao origins,and total discriminant accuracy were 97.85%and 96.4%,respectively.Tea samples from the two producing areas wereeffectively distinguished.The significance of this study was thatlight stable isotope and multi-element characteristics of tea was associated with growingenvironment,and provided chemometrics method for discrimination of tea origin andprotected designation origin with a small geographical scale.