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

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。

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

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 of δ¹³C, δ²H, and δ¹⁸O in Shandong tea was not significant; δ²H and δ¹⁸O of littoral were higher than that of inland near littoral, and δ¹⁸O was linearly correlated with δ²H (R²=0.8175); δ¹⁵N 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.