我国有机茶稳定同位素特征与δ^(15)N标识相关性研究

Characteristics of Stable Isotopes in Chinese Organic Tea and Correlations With δ^(15)N Indicator

为探明我国有机茶稳定同位素分布情况及δ^(15)N标识的相关因素,本研究收集了全国不同地区申请有机茶认证企业的145个样品,采用元素分析-稳定同位素比率质谱仪测定稳定同位素比率(δ^(13)C、δ^(15)N、δ^(2)H、δ^(18)O),结合单因素方差分析和正态分布模型探究稳定同位素特征分布规律。结果表明,有机茶样品δ^(13)C分布于-31.0‰~-23.7‰之间,不同产地间差异不显著。δ^(2)H和δ^(18)O范围分别为-107.1‰~-24.8‰和17.2‰~32.0‰,均存在显著地域差异。我国有机茶δ^(15)N正态分布范围为-4.6‰~7.0‰,平均值为1.2‰。其中有机茶生产面积大的地区样品δ^(15)N范围为1.6‰~5.8‰,显著高于生产面积小的地区(-2.5‰~0.4‰,P<0.01),表明δ^(15)N指标作为有机茶标识特征与产区生产面积之间存在一定的相关性。本研究为基于稳定同位素技术的有机茶真伪鉴别提供了研究基础,为有机茶的认证与监管提供了一定的理论依据。

The aim of the present study was to explore the distribution of stable isotopes in Chinese organic tea,and correlations withδ^(15)N indicator.145 organic tea samples produced in certified companies were collected from different regions,and the stable isotope ratio(δ^(13)C、δ^(15)N、δ^(2)H、δ^(18)O)of organic tea were determined by elemental analyzer-stable isotope ratio mass spectrometry.The distribution of stable isotope characteristics was investigated using one-way analysis of variance and normal distribution model.The results showed thatδ^(13)C values in organic teas were-31.0‰~-23.7‰,with no significant differences among regions.The range ofδ^(2)H andδ^(18)O were-107.1‰~-24.8‰and 17.2‰~32.0‰,respectively,showing significant differences in organic teas produced from different regions.The range ofδ^(15)N values was-4.6‰~7.0‰for normal distribution,and the average was 1.2‰.The tea samples produced from regions with large production area had significant higherδ^(15)N values with the range of 1.6‰~5.8‰,than samples produced from regions with small production area(-2.5‰~0.4‰,P<0.01).This study suggested thatδ^(15)N value as an indicator of organic teas was correlated with the production area.The present study provides research basis for the application of stable isotopes in discrimination of organic teas,which also supplies theoretical basis for the certification and supervision of organic teas.