Identification of geographical origin of Keemun Black Tea based on its volatile composition coupled with multivariate statistical analyses
Shimao Fang, Jingming Ning*, Wenjing Huang, Gang Zhang, Wei-Wei Deng, Zhengzhu Zhang
J Sci Food Agric (2018)
BACKGROUND: Keemun black tea (KBT) is one of the most popular tea beverages in China due to its unique flavor and potential health benefits. The geographical origin of KBT influence its quality and price. The present study aimed to apply head-space solid phase microextraction (SPME) approach, and gas chromatography-mass spectrometry (GC–MS) combined with chemometric analysis to profile the volatile compounds of KBT collected from five production areas.
RESULTS: Thirty-one peaks were detected in 61 KBT samples using hierarchical cluster analysis (HCA), principal component analysis (PCA), k-nearest neighbor (k-NN) and stepwise linear discriminant analysis (SLDA) were employed to visualize the volatile fractions. The results of unsupervised statistical tools were compared using a test for similarities and distinctions, which showed that different sources may be associated. The satisfying combination of average recognition (91.7%) and cross-validation prediction abilities (84.6%) were obtained for the PCA–k-NN. Among all statistical tools, SLDA provided promising results with 100% recognition and 96.4% prediction ability.
CONCLUSION: The results indicated that the volatile compounds can be used as indicators to identify the geographical origin of KBT. These findings could assist researchers in understanding the caffeine-related mechanisms in Camellia plants containing low, normal, and high caffeine content and be applied to caffeine regulation and breeding improvement in future research.