基于咖啡碱和氨基酸中碳氮稳定同位素比率的不同年份普洱生茶真实性认证

采用咖啡碱和氨基酸中碳氮稳定同位素比率分析方法（气相色谱-燃烧-同位素比值质谱，GC-C-IRMS）开展不同年份普洱生茶真实性认证研究。化学计量学分析表明，基于茶叶咖啡碱和氨基酸中碳氮稳定同位素比率结合化学计量学模型可以对不同年份普洱生茶进行有效区分，预测和验证准确率均达到80%以上，其中BP-ANN认证性能最优，预测和验证准确率均达到100%；进一步筛选和鉴定，得到不同年份普洱生茶的3种化学标记，包括δ15N_Thea、δ13C_Glu和δ15N_Glu。因此，基于GC-C-IRMS分析的咖啡碱和氨基酸中碳氮稳定同位素比率分析方法可以用于不同年份普洱生茶的真实性认证。本研究初步建立了普洱生茶产品认证的指标体系及技术体系，也为其他食品的认证研究提供研究思路和方法参考。

Authenticity Certification of Pu'er Raw Tea in Different Years Based on the Stable Isotope Ratios of Carbon and Nitrogen in Caffeine and Amino Acids

The method of carbon and nitrogen stable isotope ratio analysis in caffeine and amino acids (gas chromatography combustion isotope ratio mass spectrometry, GC-C-IRMS) was used to carry out the authenticity certification of Pu'er raw tea in different years. Chemometrics analysis showed that the stable isotope ratios of carbon and nitrogen in caffeine and amino acids combined with chemometrics model could effectively distinguish Pu'er raw tea in different years. And the accuracy of prediction and verification were more than 80%, BP-ANN had the best certification performance, whose accuracy of prediction and verification were 100%. Through further screening and identification, three chemical markers of Pu'er raw tea in different production years were obtained, which included δ15N_Thea、δ13C_glu and δ15N_Glu. Therefore, the analysis method of carbon and nitrogen stable isotope ratios in caffeine and amino acids based on GC-C-IRMS could be used to authenticate the authenticity of Pu'er raw tea in different years. This study preliminarily established the index system and technical system of Pu'er tea product certification, which also provided research ideas and method references for other food certification research.