Chinese Green Tea Research Articles

1H NMR Spectroscopy Combined with Machine-Learning Algorithm for Origin Recognition of Chinese Famous Green Tea Longjing Tea.

Premium green tea is a high-value agricultural product significantly influenced by its geographical origin, making it susceptible to food fraud. This study utilized nuclear magnetic resonance (NMR) spectroscopy to perform chemical fingerprint analysis on 78 Longjing tea (LJT) samples from both protected designation of origin (PDO) regions (Zhejiang) and non-PDO regions (Sichuan, Guangxi, and Guizhou) in China. Unsupervised algorithms and heatmaps were employed for the visual analysis of the data from PDO and non-PDO teas while exploring the feasibility of linear and nonlinear machine-learning algorithms in discriminating the origin of LJT. The findings revealed that the nonlinear model random forest (92.2%), exhibited superior performance compared to the linear model linear discriminant analysis (85.6%). The random forest model identified 15 key marker metabolites for the geographical origin of LJT, such as kaempferol glycoside, glutamine, and ECG. The results support the conclusion that the integration of NMR with machine-learning classification serves as an effective tool for the quality assessment and origin identification of LJT.

Characterization of the aroma-active compounds in Xiaokeng green tea by three pretreatment methods combined with gas chromatography−olfactometry (GC-O)

Chinese Xiaokeng green tea (XKGT) possesses elegant and fascinating aroma characteristics, but its key odorants are still unknown. In this study, 124 volatile compounds in the XKGT infusion were identified by headspace-solid phase microextraction (HS-SPME), stir bar sorptive extraction (SBSE), and solvent extraction-solid phase extraction (SE-SPE) combined with gas chromatography-mass spectrometry (GC–MS). Comparing these three pretreatments, we found HS-SPME was more efficient for headspace compounds while SE-SPE was more efficient for volatiles with higher boiling points. Furthermore, SBSE showed more sensitive to capture ketones then was effective to the application of pretreatment of aroma analysis in green tea. The aroma intensities (AIs) were further identified by gas chromatography–olfactometry (GC-O). According to the AI and relative odor activity value (rOAV), 27 compounds were identified as aroma-active compounds. Quantitative descriptive analysis (QDA) showed that the characteristic aroma attributes of XKGT were chestnut-like, corn-like, fresh, and so on. The results of network analysis showed that (E, Z)-2,6-nonadienal, nonanal, octanal and nerolidol were responsible for the fresh aroma. Similarly, dimethyl sulfide, (E, E)-2,4-heptadienal, (E)-2-octenal and β-cyclocitral contributed to the corn-like aroma. Furthermore, indole was responsible for the chestnut-like and soybean-like aroma. This study contributes to a better understanding of the molecular mechanism of the aroma characteristics of XKGT.

A sensor array based on a nanozyme with polyphenol oxidase activity for the identification of tea polyphenols and Chinese green tea

Green tea is popular among consumers because of its high nutritional value and unique flavor. There is often a strong correlation among the type of tea, its quality level and the price. Therefore, the rapid identification of tea types and the judgment of tea quality grades are particularly important. In this work, a novel sensor array based on nanozyme with polyphenol oxidase (PPO) activity is proposed for the identification of tea polyphenols (TPs) and Chinese green tea. The absorption spectra changes of the nanozyme and its substrate in the presence of different TPs were first investigated. The feature spectra were scientifically selected using genetic algorithm (GA), and then a sensor array with 15 sensing units (5 wavelengths × 3 time) was constructed. Combined with the support vector machine (SVM) discriminative model, the discriminative rate of this sensor array was 100% for different concentrations of typical TPs in Chinese green tea with a detection limit of 5 μM. In addition, the identification of different concentrations of the same tea polyphenols and mixed tea polyphenols have also been achieved. Based on the above study, we further developed a facile and efficient new method for the category differentiation and adulteration identification of green tea, and the accuracy of this array was 96.88% and 100% for eight types of green teas and different adulteration ratios of Biluochun, respectively. This work has significance for the rapid discrimination of green tea brands and adulteration.

Impact of drinking chinese green tea on postoperative short outcomes for gastric cancer: A randomized controlled trial

Impact of drinking chinese green tea on postoperative short outcomes for gastric cancer: A randomized controlled trial

Decoding the Chemical Signatures and Sensory Profiles of Enshi Yulu: Insights from Diverse Tea Cultivars.

Enshi Yulu, a renowned Chinese steamed green tea, is highly valued for its unique sensory attributes. To enhance our comprehensive understanding of the metabolic variation induced by steaming fixation, we investigated the overall chemical profiles and organoleptic quality of Enshi Yulu from different tea cultivars (Longjing 43, Xiapu Chunbolv, and Zhongcha 108). The relationships between sensory traits and non-volatiles/volatiles were evaluated. A total of 58 volatiles and 18 non-volatiles were identified as characteristic compounds for discriminating among the three tea cultivars, and the majority were correlated with sensory attributes. The "mellow" taste was associated with L-aspartic acid, L-asparagine, L-tyrosine, L-valine, EGC, EC, and ECG, while gallic acid and theobromine contributed to the "astringent" taste. "Kokumi" contributors were identified as L-methionine, L-lysine, and GCG. Enshi Yulu displayed a "pure" and "clean and refreshing" aroma associated with similar volatiles like benzyl alcohol, δ-cadinene, and muurolol. The composition of volatile compounds related to the "chestnut" flavor was complex, including aromatic heterocycles, acids, ketones, terpenes, and terpene derivatives. The key contributors to the "fresh" flavor were identified as linalool oxides. This study provides valuable insights into the sensory-related chemical profiles of Enshi Yulu, offering essential information for flavor and quality identification of Enshi Yulu.

Investigation of the effect of over-fired drying on the taste and aroma of Lu’an Guapian tea using metabolomics and sensory histology techniques

Lu’an Guapian (LAGP) tea, a representative Chinese roasted green tea, undergoes significant changes in taste and aroma during over-fired drying. However, limited studies have been conducted on these effects. This study employed metabolomics and sensory histology techniques to analyze non-volatile and volatile compounds the second drying and pulley liquefied gas drying (PLD) samples. The results revealed that after PLD, the samples exhibited lower umami, bitterness, and astringency; whereas floral, sweet, roasted, cooked corn-like, and cooked chestnut-like aromas became stronger. Among them, the content of (−)-epigallocatechin gallate, glutamic acid, and theogallin, which were closely related to taste, decreased by 4.5 %, 12.3 %, and 10.4 %, respectively. Eight key aroma components were identified as the main contributors to the sample aroma changes: (E)-β-ionone, dimethyl sulfide, (E,E)-2,4-heptadienal, geraniol, linalool, benzeneacetaldehyde, 2-ethyl-3,5-dimethylpyrazine, and hexanal. This study provides a theoretical basis for enhancing the quality of LAGP teas.

A green synthesized medicine residue carbon-based iron composite for the removal of chromium (VI) and cadmium (II): Performance, kinetics and mechanism.

Nowadays, clean-up of heavy metals from wastewaters using waste residue carbon-based material has received increasing attention. In this work, a novel Chinese medicine residue carbon-based nano zero-valent iron composite (CM-nZVI) had been successfully prepared using the combined Chinese medicine residue, FeCl3 and green tea extract. Cr(VI) and/ or Cd(II) removal in water by the CM-nZVI were systematacially investigated with a series of batch experiments. The most relevant findings indicated the adsorption efficiecy and capacity of Cr(VI) by CM-nZVI were respecitvely nearly 98% and 26mg/g under optimized reaction conditions. The negative influences of the cations on the Cr(VI) removal followed the order of Al3+ > Ca2+ > Mg2+ Na+ > K+, but the anions followed the order of HCO3- > PO43- > NO3- > Cl- > SO42-. Humic acid (HA) and ionic strength with high concentrations severely inhibited Cr(VI) removal. The Cr(VI) adsorption on CM-nZVI fitted well by the pseudo-second-order kinetic and Langmuir models. A monolayer endothermic chemisorption occurred on Cr(VI) adsorption over CM-nZVI, and Cr(VI) removal by CM-nZVI primarily involved in the absorption, reduction, precipitation and complexation processes. Both Cr(VI) and Cd(II) removals had been achieved by CM-nZVI at their low concentrations. This CM-nZVI showed a better reusability proprity for Cr(VI) and Cd(II) removal with the regeneration of CM-nZVI through simple pickling. The outcomes of this work show that CM-nZVI could be used an effective material for heavy metals removal from water.

The Role of Chinese Green Tea and Tourism Development in Hunan Province

The Role of Chinese Green Tea and Tourism Development in Hunan Province

Examining Consumer Perception and Purchase Intention of Gift Packaging: A Case Study of Chinese Consumers on Green Tea Packaging

Tea industry in China is continuing flourish and the sales volume increasing. It is significant for China tea industry focuses on upgrading their marketing strategy in boosting consumption and make it exclusive in the international market. The aim of this research was to identify the impact of gift packaging on consumer perception and their purchase intention. The literature revealed the colour of packaging influences consumer perception and purchase intention in China. This paper proposes two research questions; (1) Does packaging elements influence consumer perception and purchase intention? And (2) Does packaging elements increases business sales to different culture? Findings of this study can be added into current knowledge and literature for future reference. Furthermore, the findings show that consumers have spatial visual attention shifting from product to another product and impact on their evaluation of product evaluation and satisfaction. The findings also show that consumers perceive the brand with distinctive and unique meanings through its packaging elements that meet with contemporary consumers' functional and psychological needs. Additionally, the new insights obtained from this research are important for Chinese green tea businesses and marketers on determining long-term new product developments and in developing the marketing mix for packaging elements that are marketed and can influence consumer purchase intention. This research indicated that utilising packaging elements to influence consumer perception and their purchase intention.

Discrimination of Chinese green tea according to tea polyphenols using fluorescence sensor array based on Tb (III) and Eu (III) doped Zr (IV) metal–organic frameworks

A facile and rapid fluorescence sensor array based on Tb (III) and Eu (III) doped Zr (IV) metal–organic frameworks was proposed for Chinese green tea discrimination. According to large porosity of Tb@UiO-66-(COOH)2 and Eu@UiO-66-(COOH)2, phenolic hydroxyl groups of tea polyphenols could coordinate with free carboxylic acid groups and was captured into the pores, which led to the disturbance of electronic structure of ligand and inhibited the energy transfer efficiency from ligand to Tb (III) and Eu (III) center, causing the fluorescence quenching effect. Based on Hierarchy Cluster Analysis and Linear Discrimination Analysis, the fluorescence sensor array was employed for successful tea polyphenols classification through the analysis of different fluorescence quenching effect to tea polyphenols. Green tea samples within different categories and grades were also successfully discriminated using this assay according to tea polyphenols, providing a new method for Chinese green tea identification.

Induction of Apoptosis via Inactivating PI3K/AKT Pathway in Colorectal Cancer Cells Using Aged Chinese Hakka Stir-Fried Green Tea Extract.

Food extract supplements, with high functional activity and low side effects, play a recognized role in the adjunctive therapy of human colorectal cancer. The present study reported a new functional beverage, which is a type of Chinese Hakka stir-fried green tea (HSGT) aged for several years. The extracts of the lyophilized powder of five HSGT samples with different aging periods were analyzed with high-performance liquid chromatography. The major components of the extract were found to include polyphenols, catechins, amino acids, catechins, gallic acid and caffeine. The tea extracts were also investigated for their therapeutic activity against human colorectal cancer cells, HT-29, an epithelial cell isolated from the primary tumor. The effect of different aging time of the tea on the anticancer potency was compared. Our results showed that, at the cellular level, all the extracts of the aged teas significantly inhibited the proliferation of HT-29 in a concentration-dependent manner. In particular, two samples prepared in 2015 (15Y, aged for 6 years) and 2019 (19Y, aged for 2 years) exhibited the highest inhibition rate for 48 h treatment (cell viability was 50% at 0.2 mg/mL). Further, all the aged tea extracts examined were able to enhance the apoptosis of HT-29 cells (apoptosis rate > 25%) and block the transition of G1/S phase (cell-cycle distribution (CSD) from <20% to >30%) population to G2/M phase (CSD from nearly 30% to nearly 10%) at 0.2 mg/mL for 24 h or 48 h. Western blotting results also showed that the tea extracts inhibited cyclin-dependent kinases 2/4 (CDK2, CDK4) and CylinB1 protein expression, as well as increased poly ADP-ribose polymerase (PRAP) expression and Bcl2-associated X (Bax)/B-cell lymphoma-2 (Bcl2) ratio. In addition, an upstream signal of one of the above proteins, phosphatidylinositol 3-kinase (PI3K)/protein kinase B (AKT) signalling, was found to be involved in the regulation, as evidenced by the inhibition of phosphorylated PI3K and AKT by the extracts of the aged tea. Therefore, our study reveals that traditional Chinese aged tea (HSGT) may inhibit colon cancer cell proliferation, cell-cycle progression and promoted apoptosis of colon cancer cells by inactivating PI3K/AKT signalling.

GC-MS-based untargeted metabolomics reveals the key volatile organic compounds for discriminating grades of Yichang big-leaf green tea

In this work, headspace gas chromatography coupled to mass spectrometry (HS-GC-MS) combined with multivariate statistical analysis was applied to reveal volatile markers from different grades of Yichang big-leaf green tea (YBGT). A total of 94 volatile organic compounds (VOCs) were detected and identified, which can be categorized as alkanes, terpene, aromatics, ketone, ester, alcohol, heterocyclic compounds, aldehyde, olefin, acid, amine, and nitrogen compounds. The differences between low-grade and high-grade YBGT were demonstrated by principal component analysis (PCA) and hierarchical cluster analysis (HCA). Based on orthogonal partial least squares discriminant analysis (OPLS-DA), 19 VOCs were screened as markers for the discrimination of first-grade and second-grade YBGT, and 25 VOCs were screened as markers to distinguish first-grade from third-grade YBGT. Among them, 16 VOCs are common, which can be used as characteristic markers to distinguish low-grade from high-grade YBGT. Overall, our findings indicated that there are significant differences in VOCs among different grades of YBGT, and HS-GC-MS in combination with chemometric multivariate statistical analysis can be extended as a reliable strategy for discriminating grades of other Chinese green teas.

Discrimination of geographical indication of Chinese green teas using an electronic nose combined with quantum neural networks: A portable strategy

Sensory attributes of teas are related to their geographical origin and directly affect consumer preference and thus the value of products. In this paper, we propose a portable strategy of identifying five famous green teas with official geographical indications of China using a lab-made electronic nose combined with a quantum neural network (QNN). QNN can be regarded as a modified version of back propagation neural network (BPNN), in which transfer functions are superposed by several sigmoids forming multilevel intervals and can be adjusted during training. Firstly, principal component analysis and linear discriminant analysis are used for low-dimensional visualization. Then different QNNs with 2–6 quantum intervals are trained and tested compared with BPNN, support vector machine (SVM) and k-nearest neighbor (k-NN). The results show that averaged classification accuracies of QNNs are higher than that of BPNN, SVM and k-NN, and they raise with increasing of initial quantum intervals but vary a little when quantum intervals exceed 3, and reach highest to 99.38 %, indicating 3 quantum intervals is adequate for this application considering the trade-off between calculating cost and classification accuracy. The results demonstrate that QNN is a promising pattern recognition method for portable electronic noses due to its better generalization ability but simple implementation as a conventional BPNN.

Spent Chinese Green Tea as an Adsorbent for Simultaneous Removal of Potentially Toxic Metals from Aqueous Solution

Spent Chinese Green Tea as an Adsorbent for Simultaneous Removal of Potentially Toxic Metals from Aqueous Solution

Potential role of tea drinking in preventing hyperuricaemia in rats: biochemical and molecular evidence

BackgroundLifestyle and diet play a significant role in hyperuricaemia. Accumulating evidence indicates that tea consumption is associated with hyperuricaemia and gout. However, diverse compounds in different types of tea make it quite difficult to determine the relevant molecular mechanism. Here, we compared the effects of six types of tea on hyperuricaemia induced by potassium oxonate (PO) and hypoxanthine in rats and investigated the possible underlying mechanisms.MethodsRats were randomly assigned to ten groups: the control, hyperuricaemia model, benzbromarone positive control, traditional Chinese medicine Simiao San positive control, green tea, yellow tea, black tea, white tea, red tea, and cyan tea treatment groups. After 21 days, uric acid (UA), xanthine oxidase (XOD), alanine aminotransferase (ALT),blood urea nitrogen (BUN), and creatinine (CRE) were assessed. Serum levels of interleukin-1β (IL-1β) were measured with an enzyme-linked immunosorbent assay. Haematoxylin–eosin staining and immunohistochemistry were used to assess liver and kidney injury.ResultsThe levels of UA, CRE, and BUN in the treatment group were decreased to varying degrees. There was a significant reduction in UA, CRE, and BUN levels for yellow tea compared to the positive control drugs. Yellow tea suppressed XOD activity and alleviated hepatic and kidney injury. Network pharmacology and untargeted metabolomics indicated that ten yellow tea bioactive ingredients and 35 targets were responsible for preventing hyperuricaemia, which was mediated by 94 signalling pathways, including IL-1β and TNF.ConclusionThese findings indicate that green tea cannot reduce the serum uric acid level of hyperuricaemic rats. Yellow tea can significantly improve hyperuricaemia by regulating the inflammatory response, autophagy, and apoptosis. This study provides a potential candidate for the treatment of hyperuricaemia and a basis for selecting therapeutic tea for patients with hyperuricaemia.

The Endogenous Development Mechanism of the Baiyankeng Geocultural Village in China

This study aims to clarify a new endogenous model of geocultural villages by examining land use change, industrial transformation, and their impacts on rural society and the economy of Baiyankeng village, Zhejiang Province, China. This empirical study focuses on the actions of residents and their effects after Baiyankeng was registered as the pilot geocultural village in China. To address the dual configuration of urban/rural areas and three-dimensional rural issues, the Chinese government released a set of policies for rural vitalization in the early 2000s, which included the establishment and promotion of geocultural villages in 2013. This study found that the local leadership—the township government and the village committee—played a significant role in leveraging the unique geological resources of the village. They aggressively pitched for Baiyankeng village to be recognized as the first-ever geocultural village, and successfully established an effective model of self-governance that empowered villagers to actively and enthusiastically participate in the process. By doing so, they successfully created a booming tourism industry while boosting local production of Chinese Torreya nuts and green tea. From the perspective of the land system in China, the mechanism of geocultural villages (henceforth known as rural geoparks) in this study shows new endogeneities of rural vitalization in China.

Effect of thermal process on the key aroma components of green tea with chestnut‐like aroma

Chestnut-like aroma is one of the unique qualities of Chinese green tea and has become an important factor influencing consumer decisions. However, the chemical formation mechanism of chestnut-like aroma during green tea processing remains unclear. In this study, the dynamic changes of key components contributing to chestnut-like aroma and their precursors were analyzed in fresh leaves, fixation leaves, first baking tea leaves, and green tea. The thermal process had an important effect on volatile components in tea leaves, causing a significant decrease of alcohols and esters and a significant increase of ketones, acids, phenols, and sulfur compounds. Furthermore, 31 volatiles were identified as the key odorants responsible for chestnut-like aroma of green tea, including dimethyl sulfide, methyl isobutenyl ketone, 2-methylbutanal, 2,4-dimethylstyrene, d-limonene, methyl 2-methylvalerate, linalool, decanal, longifolene, phenylethyl alcohol, l-α-terpineol, jasmone, and so on. And the majority of these odorants were only formed in the drying stage. Additionally, isoleucine, theanine, methionine, and glucose were found to be involved in the formation of chestnut-like aroma of green tea. The drying process played a vital important role in the formation of chestnut-like aroma of green tea. © 2022 Society of Chemical Industry.

Geographical origin identification and chemical markers screening of Chinese green tea using two-dimensional fingerprints technique coupled with multivariate chemometric methods

Identifying the geographical origins of green teas produced in specific regions is of significance since the geographical origin of tea influences its quality and price greatly. In this work, a novel two-dimensional (2D) fingerprints acquired by high-performance liquid chromatography-diode array detector (HPLC-DAD) was firstly proposed to identify geographical origins of Chinese green teas. A total number of 62 chemical components were extracted from 2D HPLC-DAD fingerprints of 78 tea samples by multivariate curve resolution-alternating least squares (MCR-ALS) algorithm. Afterward, principal component analysis (PCA) and orthogonal partial least squares-discriminant analysis (OPLS-DA) were used to classify tea samples based on the extracted components. Inspection of PCA score plots of two scaling types (UV and Par) showed that tea samples from two different geographical origins have an obvious clustering tendency. As for the OPLS-DA analysis, the Q 2 cum of two types-scaling OPLS-DA models are greater than 0.75, and the total recognition rates for test set are 92.86%. What's more, according to p value of t -test, VIP values, V-plot and S-plot, 17 characteristic components were screened and identified as chemical markers to distinguish between Zhejiang teas and Shandong teas. This work indicated that the proposed strategy is suitable for identifying geographical origins of Chinese green teas. • 2D HPLC-DAD fingerprints was proposed to identify geographical origins of tea. • 62 chemical components were extracted from 2D HPLC-DAD fingerprints by MCR-ALS. • PCA and OPLS-DA were used to classify tea samples using the extracted components. • 17 characteristic components were screened and identified as chemical markers. • There are correlations between chemical components and geographical origins of tea.

Are organic acids really related to the sour taste difference between Chinese black tea and green tea?

Sour is an important taste in some foods, beers, and teas; organic acids, in particular, are thought to play a key role in the formation of the sour taste of beer. It has been generally thought that organic acids also contribute to some teas tasting sour. In this study, through sensory evaluation experiments with black tea (BT) and green tea (GT), the difference in the sour taste of BT and GT was quantitatively characterized. Then the organic acids in the two types of tea were identified and quantified via high‐performance liquid chromatography (HPLC) with taste activity value (TAV) analysis. The results showed that both teas had 12 identical common organic acids (including 11 taste‐active components), but the results of the TAV analysis were not consistent with those of the sensory evaluation. Therefore, there is no direct relationship between organic acids and the acidity in BT and GT. It is related to the interaction between organic acids and other substances, pH value, or other sour substances in tea infusions. The mechanism of the disappearance of sourness in tea infusions was also discussed. These results help us to understand the correlation between tastes in teas.

Effects of different tea tree varieties on the color, aroma, and taste of Chinese Enshi green tea.

Green tea processed by Echa 10 was shown to have a fresh and mellow taste as well as clean aroma with a clear honeysuckle fragrance. The colors of different Enshi green teas are closely related with the content of chlorophyll and chlorophyllide. The five green teas also vary in their aroma style. Echa 10 imparts a special honeysuckle fragrance, which was further analyzed by molecular sensory analysis and the formation of this honeysuckle fragrance was attributed to the key components of dodecane, octadecane, phenethyl alcohol, and jasmonone. In aroma evaluation, Echa 10 green tea showed the best performance, which is mainly related with the content of geraniol, linalool, phenethyl alcohol, and benzyl alcohol. Additionally, Echa 10 scored the highest in taste evaluation, which is mainly determined by the contents and ratios of tea polyphenols, amino acids, caffeine, and soluble sugars.