Identification of geographical origin of Keemun black tea based on its volatile composition coupled with multivariate statistical analyses

Abstract

BACKGROUND: Keemun black tea (KBT) is one of the most popular tea beverages in China as a result of its unique flavor and potential health benefits. The geographical origin of KBT influences its quality and price. The present study aimed to apply a head-space solid phase microextraction approach and gas chromatography-mass spectrometry 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. Hierarchical cluster analysis, 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. A satisfying combination of average recognition (91.7%) and cross-validation prediction abilities (84.6%) was obtained for the PCA-k-NN. Among all of the statistical tools, SLDA provided promising results, with 100% recognition and 96.4% prediction ability. CONCLUSION:The results obtained in the present study indicate that the volatile compounds can be used as indicators to identify the geographical origin of KBT.

Discrimination and Identification of Aroma Profiles and Characterized Odorants in Citrus Blend Black Tea with Different Citrus Species

“…Limonene and β-myrcene were the most important volatile components in orange ( Citrus sinensis ), lemon ( Citrus limon ), and mandarin ( Citrus reticulata ), and a very low content had also been identified in pure tea [ 12 , 13 , 19 , 20 ]. Compared with the previous report in lemon and tea, p -Cymene was much higher in our results [ 7 , 13 , 18 , 21 ]. It was supposed that p -cymene and linalool may come from both citrus and tea leaves.…”

“…In detail, limonene was absolutely the highest constituent (CG, 35.41%; BG, 26.10%; LG, 29.44%), followed by β-myrcene (CG, 4.75%; BG, 5.73%; LG, 4.25%). Benzaldehyde was the main aldehyde, which was reported in many famous Chinese black teas, and considered as a key aroma compound in them contributing floral odorant [ 17 , 18 ]. p -Cymene, a common aromatic hydrocarbon in nature, with various biological activities, was detected in a high level (CG, 2.82%; BG, 6.93%; LG, 5.80%).…”

Region identification of Xinyang Maojian tea using UHPLC‐Q‐TOF/MS‐based metabolomics coupled with multivariate statistical analyses

“…Due to the differences of region conditions including temperature, precipitation and altitude (Fang et al., 2017; Liang et al., 2008), previous studies showed the differential compounds contributed to the identification of geographical origin (Fang, Huang et al., 2019; Fang, Ning et al., 2019; Xin et al., 2018). Based on the differential metabolites related to production place (Supporting information Table S1) and tea cultivar (Supporting information Table S2), KEGG metabolic pathway analysis was carried out with Arabidopsis thaliana as the corresponding species (Figure 7).…”

Geographical origin traceability of Keemun black tea based on its non‐volatile composition combined with chemometrics

“…The characteristic sensory and the nutritional properties of KBT vary slightly depending on its geographical origin . There are several famous tea subregions in China such as Longjing Village, Anxi Town, Qimen Town, and Dongting Mountain, and tea cultivation areas with long history .…”

“…The characteristic sensory and the nutritional properties of KBT vary slightly depending on its geographical origin. 2 There are several famous tea subregions in China such as Longjing Village, Anxi Town, Qimen Town, and Dongting Mountain, and tea cultivation areas with long history. 3,4 As the price of KBT from Qimen Town is much higher than other black teas from adjacent regions (such as Guichi and Dongzhi County), many imitation products have existed in almost all tea-production areas in Anhui Province in recent years, causing confusion in the tea market.…”