基于咖啡碱和氨基酸中碳氮稳定同位素比率的茶叶地理溯源

采用咖啡碱和氨基酸中碳氮稳定同位素比率分析方法，基于气相色谱-燃烧-同位素比值质谱（gas chromatography combustion isotope ratio mass spectrometry，GC-C-IRMS）开展不同产地茶叶地理溯源技术研究。结果表明，基于GC-C-IRMS特异性化合物稳定同位素比值分析方法可以用于茶叶地理溯源；化学计量学分析表明，本方法可以对不同产地茶叶进行有效区分，预测和验证准确率均达到85%以上，BP人工神经网络认证性能最优，预测和验证准确率均达到100%；经过进一步筛选和鉴定，得到不同产地秀芽的2 种特征标识化合物——δ15N丙氨酸和δ13C茶氨酸。本研究可为茶叶地理溯源提供一定技术支撑，有利于茶叶产品的认证体系的建立和完善。

Geographical Traceability of Tea Based on Carbon and Nitrogen Stable Isotope Ratios in Caffeine and Amino Acids

The geographical traceability of tea from different production areas was studied by gas chromatography combustion isotope ratio mass spectrometry (GC-C-IRMS) based on carbon and nitrogen stable isotope ratios in caffeine and amino acids. The results showed that GC-C-IRMS combined with compound specific stable isotope ratio analysis could be used to trace the geographical origin of tea. Chemometrics analysis showed that this method could effectively distinguish tea from different production areas, with accuracy of prediction and verification more than 85%. BP artificial neural network had the best authentication performance, with accuracy of prediction and verification of 100%. After further screening and identification, two characteristic marker compounds, δ15Nalanine and δ13Ctheanine, were obtained for Xiuya green tea from different production areas. This study can provide some technical support for geographical traceability of tea and help to establish a sound certification system for tea products.