Journal of Tea Science

Review on the Formation Pathway of Kombucha Bacterial Cellulose and Its Application in Efficient Utilization of Tea Waste

XU Qingqing, NIE Qing, LIU Zhusheng, GUO Qing, LIU Zhonghua, CAI Shuxian

Journal of Tea Science. 2024, 44(5): 707-717. doi:10.13305/j.cnki.jts.2024.05.001

Abstract ( 190 )

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Tea waste and summer-autumn tea can be used to produce Kombucha and bacterial cellulose, helping to reduce environmental pollution and resource waste while developing high market value products. Bacterial cellulose, as a highly crystalline and sustainably renewable polysaccharide, has a wide range of potential applications in biomedicine, eco-friendly packaging, textiles, new energy batteries, skincare products, and other fields. This paper reviewed recent research on the applications of bacterial cellulose membranes, focusing on the effects of different fermentation environments and tea types on the quality of bacterial cellulose membranes. It confirmed that adjusting fermentation parameters can produce cellulose with specific crystalline structures. The paper also discussed the role of tea components in the formation of bacterial cellulose membranes and proposed new ideas for improving the yield and quality of Kombucha bacterial cellulose membranes. The health benefits of Kombucha bacterial cellulose membranes and their significant role in sustainable product development were emphasized. The paper highlighted the need for further research to promote their industrial application.

Physiological Response of Tea Plants Inoculated with Arbuscular Mycorrhizal Fungi under Drought Stress

LU Wei, WU Xiaolong, HU Xianchun, HAO Yong, LIU Chunyan

Journal of Tea Science. 2024, 44(5): 718-734. doi:10.13305/j.cnki.jts.2024.05.002

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To explore the mechanism of arbuscular mycorrhizal (AM) fungi on the growth and physiological characteristics of tea plants under drought stress, tea cultivar ‘Fuding Dabaicha' was used as experimental material to inoculate with or without (Claroideoglomus etunicatum) under well-watered and drought stress. Plant growth performance, photosynthesis, osmotic regulation and stomatal aperture were determined to investigate the effect of AMF on tea seedlings under different duration of DS (4 weeks, 6 weeks and 8 weeks). The results show that under well-watered and drought stress conditions, AMF inoculation significantly promoted plant growth performance, increased the shoot and root biomass, improved the root system architecture, in particularly increased total root length, secondary and tertiary lateral root numbers, and leaf osmotic potential by 20.00%-38.77%, 48.90%-163.33%, 60.00%-442.86%, 29.77%-41.24%, decreased the stomatal density and relative conductance under drought stress by 16.00%-42.37% and 2.21%-6.67% respectively. The effects were more significant under drought stress. Whereas, drought stress significantly inhibited the root AMF colonization and plant growth, as evidenced by impaired establishment of root system architecture, reduced leaf chlorophyll content, maximum light quantum effect (QY_max), leaf relative water content, stomatal aperture and osmotic potential, etc. AMF inoculation could significantly alleviate this inhibitory effect, improve the physiological response of tea plants under drought stress and thus promote tea plant growth. The results indicate that AMF could promote the absorption of water and nutrients, alleviate the damage of drought stress and improve the drought resistance of tea seedlings by improving root morphology, promoting the water retention and photosynthetic capacity, adjusting the stomatal and osmotic balance, and the promotion effect of AMF became more significant with the extension of drought time.

Investigation of Differential Fluorine Enrichment in Leaf Cell Walls of Different Tea Cultivars

LIU Yu, YANG Peidi, ZHANG Peikai, ZHAN Wenli, LI You, YAO Suhang, ZHAO Yang, CHENG Yang, LIU Zhen, SHEN Chengwen

Journal of Tea Science. 2024, 44(5): 735-746. doi:10.13305/j.cnki.jts.2024.05.003

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Tea plants are known to hyperaccumulate fluorine, with significant variation in fluorine accumulation among different cultivars. To explore the patterns of fluorine accumulation in tea leaf cell walls, the fluorine content in leaves of 15 tea cultivars was measured. Moreover, the contents of pectin, hemicellulose, cellulose components, and their respective fluorine contents were analyzed. The distribution of fluorine in the cell walls at different maturity stages of leaves were examined. The results indicate that pectin is a crucial component reflecting the differences in fluoride accumulation and maturity level of the cell walls among cultivars. Only the mature leaves of ‘Liancha 7', ‘Zhuyeqi' and ‘Shangmeizhouzhong' increased pectin content and fluoride content in pectin compared to the young leaves. ‘Tieguanyin' was the only cultivar with the fluoride content in pectin decreased in the mature leaves compared to the young leaves. Correlation analysis of the fluoride proportion in the cell wall components reveals that higher fluoride content in the leaves correlates with greater maturity, reflecting a trend of multi-component fluoride accumulation in the cell walls. Through a comprehensive evaluation and cluster analysis, ‘Hanlü' exhibits consistently high levels of fluorine accumulation in cell walls at different maturity stages (D_1-4=0.704 6, D_5-8=0.928 6). ‘Fuding Dabaicha', ‘Xiangbolü', ‘Xiangbolü 2', ‘Biyun', and ‘Qianmei 702' show moderate levels of fluorine enrichment in cell walls (D_1-4=0.3267-0.4861, D_5-8=0.484 4~0.699 3), while ‘Yunnan Wuheidaye' and ‘Zhuyeqi' exhibit low levels of fluorine accumulation (D_1-4=0.146 5-0.268 8, D_5-8=0.2223-0.345 7). This study explored the regularity and difference of fluorine accumulation in tea cell walls from the perspectives of cultivar and leaf maturity, and provided insights for molecular breeding of low-fluorine tea cultivars.

Study on the Differences of Volatile Components in Jingshan Tea from Different Tea Cultivars

HOU Zhiwei, LÜ Yongming, MA Kuan, ZHANG Huiyuan, GU Zhe, ZHANG Ran, LI Le, JIN Yugu, SU Zhucheng, CHEN Hongping

Journal of Tea Science. 2024, 44(5): 747-762. doi:10.13305/j.cnki.jts.20240824.001

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To investigate the differences of volatile components in Jingshan tea from different tea cultivars, the stir bar sorptive extraction gas chromatography-mass spectrometry (SBSE-GC-MS), headspacegas chromatography-ion mobility spectrometry (HS-GC-IMS) were used to analyze the volatile components in Jingshan tea from five tea cultivars, including ‘Jingshan No. 1', ‘Jingshan No. 2', ‘Jiukeng', ‘Yingshuang' and ‘Cuifeng'. Firstly, a total of 93 volatile components were identified by GC-MS and 79 volatile components by GC-IMS. Secondly, principal component analysis (PCA) was used to reveal the differences in the volatile components of Jingshan tea from different tea cultivars. Finally, orthogonal partial least squares discriminant analysis (OPLS-DA) was used to determine the differential volatile components between different cultivars, and the relative odor activity value (ROAV) was used to further identify the key differential volatile components. The results show that 16 and 12 volatile compounds were identified as the key differential volatile compounds of different tea cultivars by SBSE-GC-MS and HS-GC-IMS respectively. Among them, the characteristic volatile components of ‘Jingshan No. 2' include 2-heptanol, methyl jasmonate, 2-methyl butanal, and 2-heptanone, which have clear fragrance characteristics and higher contents than other cultivars. The contents of methyl eugenol, hexanal, and (Z)-3-hexen-1-ol in ‘Jingshan No. 1' were relatively rich. The contents of oxidized limonene and pentanal in ‘Jiukeng' were relatively higher. The sensory evaluation results indicate that ‘Jingshan No. 1', ‘Cuifeng' and ‘Jingshan No. 2' had higher aroma scores. This study revealed that the characteristic volatile compounds in Jingshan tea from different tea cultivars have significant differences, which provided a theoretical basis for the selection of high-quality raw materials in Jingshan tea production, and had important value for achieving precise processing and targeted quality control of high-quality Jingshan tea.

Research on Flavors and Qualities of Optimization Blending Samples of Hunan Raw Dark Teas

JIANG Ating, LIU Qiaofang, XIAO Juanjuan, HE Junhui, GAO Bingcai, HUANG Jian'an, WANG Kunbo, LIU Zhonghua, YU Lijun

Journal of Tea Science. 2024, 44(5): 763-778. doi:10.13305/j.cnki.jts.20240829.001

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In order to study how to obtain the raw materials of dark tea processing with Hunan regional characteristics of mellow and fresh taste, heavy and long-lasting aroma, Zhuyeqi raw dark tea (Z), Taoyuan-daye raw dark tea (T), Huangjincha 1 raw dark tea (H) were obtained by processing the fresh leaves of relative cultivars, and six blending tea samples were obtained by blending these three raw dark tea (Z∶T∶H) with the ratio of 20∶20∶60, 20∶60∶20, 40∶15∶45, 40∶45∶15, 60∶10∶30, 60∶30∶10. Comparative analysis of their sensory evaluation, taste quality and aroma components was also conducted. The results show that when the proportion of Zhuyeqi raw dark tea was 40% and 60%, the blended teas were mellower and fresher in taste, with heavier and longer-lasting aroma than the original raw tea and the two blends with the proportion of Zhuyeqi raw dark tea of 20%. The tea samples' quality had significant improvement. The results of biochemical analysis show that, when the proportion of Zhuyeqi raw dark tea was 40% and 60%, the contents of water extract and gallic acid were higher, and the taste was mellow and fresh. On this basis, when Taoyuan-daye raw dark tea accounted for a higher percentage of tea, the contents of tea polyphenols, flavonoids, total catechins and caffeine were higher and the taste was mellow. When Huangjincha 1 raw dark tea accounted for a higher percentage of tea, the content of soluble sugar was higher, and the taste was sweeter. A total of 77 volatile components were detected by headspace-solid phase microextraction (HS-SPME) combined with gas chromatography-mass spectrometry (GC-MS). Based on the variable importance in projection (VIP) of the orthogonal partial least squares discriminant analysis method (OPLS-DA), 41 components (VIP>1) were screened out by this experiment, and by further calculating their relative odor activity value (ROAV), 13 key differential volatiles such as linalool, L-α-terpineol, cedrol, isopropylidene acetone and crocinaldehyde were identified (VIP>1, ROAV>1). When the proportion of Zhuyeqi raw dark tea was 40% and 60%, the high aroma and lasting characteristics were closely related to the high contents of saffron and aldehyde. Adding high proportion of Huangjincha 1 raw dark tea, the contents of D-limonene and linalool oxide (Ⅳ) were higher, which gave the floral aroma of the blending samples.

A Study on the Neuroprotective Effects of Combined EGCG and L-Theanine from Tea Leaves

DING Shuqia, XIE Xinya, LIU Zhusheng, LIAO Xianjun, LIU Zhonghua, CAI Shuxian

Journal of Tea Science. 2024, 44(5): 779-792. doi:10.13305/j.cnki.jts.20240918.001

Abstract ( 92 )

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Differentiated neurons need to maintain axonal growth and function in a quiescent state. Previous studies have shown that epigallocatechin gallate (EGCG) and L-theanine can maintain the quiescent state of neurons and have neurorestorative effects, although the specific mechanisms are still unclear. In the Aβ_25-35-induced PC12 cell damage model, combined treatment with EGCG and L-theanine improved cell metabolism and repair capacity, enhanced cell viability and showed a significant synergistic effect. Transcriptomic and network pharmacological analyses indicate that EGCG mainly maintains the quiescent state of cells by inhibiting oxidative stress, regulating fatty acid metabolism, and mitigating amyloid protein toxicity stress. L-theanine promotes axonal growth and regulates neuronal metabolism and synaptic function. The combined application of both compounds results in a broader and milder regulation of cellular networks, reducing cellular stress. This study provided theoretical support for the neuroprotective effects of tea and its value in an aging society.

Genetic Diversity Analysis of Euproctis pseudoconspersa and Its Bunyavirus (EpBYV) in China

CHEN Shichun, JIANG Hongyan, LIAO Shuran, CHEN Tingxu, NIU Jinzhi, WANG Xiaoqing

Journal of Tea Science. 2024, 44(5): 793-806. doi:10.13305/j.cnki.jts.2024.05.009

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Tea tussock moth, Euproctis pseudoconspersa, is an important pest which damages tea plants and causes human dermatitis. Euproctis pseudoconspersa bunyavirus, EpBYV, is a bunyavirus that widely distributed in different geographical populations of E. pseudoconspersa. In order to control the E. pseudoconspersa and utilize the virus resources, it is necessary to fully understand the genetic background of E. pseudoconspersa and EpBYV. In this study, 148 samples of E. pseudoconspersa larvae from 15 geographic populations were collected. COI and ND5 gene sequences of E. pseudoconspersa and RdRp sequences of EpBYV were determined. The genetic diversities of E. pseudoconspersa and EpBYV were analyzed by DnaSP 6.12.03, Arlequin 3.5.2.2 and MEGA 7.0.26. Sequence analysis of the combined sequences of COI and ND5 genes shows that 15 geographic populations have high haplotype diversity (h=0.880 68) and low nucleotide diversity (π=0.003 17). Significantly high genetic differentiation among 99 population pairs (F_ST>0.290, P<0.05) was identified. Molecular variance analysis (AMOVA) shows that the genetic differentiation of E. pseudoconspersa was mainly among populations (87.12%), and the differentiation among groups was consistent with the second and third ladder boundaries in China. Demographic history analysis suggests that the population of E. pseudoconspersa is relatively stable. RdRp sequences were successfully amplified in the 138 samples except CK population. RdRp sequence analysis reveals that the 14 geographic populations of EpBYV had high haplotype diversity (h=0.935 26) and relatively low nucleotide diversity (π=0.017 95). The 93 population pairs had significantly higher genetic differentiation (F_ST>0.257, P<0.05). AMOVA analysis shows that the genetic differentiation of EpBYV was mainly between populations (62.13%). Demographic history analysis reveals that EpBYV might have undergone population expansions in the past. Based on the analysis of this study, the population of E. pseudoconspersa in China is relatively stable, and there is a risk of population expansion in Chengkou, Chongqing and Ningde, Fujian. The population of EpBYV has experienced population expansion. The infection rate and population expansion ability of EpBYV in E. pseudoconspersa are high, which has good potential for biological control of E. pseudoconspersa.

Identification of the Pathogen Causing New Twig Wilting on Tea Plants and Screening of Control Chemicals

WANG Juan, TU Yiyi, LÜ Wuyun, CHEN Yijia, LI Shipu, WANG Yuchun, CHEN Yanan

Journal of Tea Science. 2024, 44(5): 807-815. doi:10.13305/j.cnki.jts.2024.05.007

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During summer and autumn, serious new twig wilting occurs on a large scale in ‘Jiaming No. 1' tea gardens of Ruian City, Wenzhou, Zhejiang Province, China. The disease initially appears as irregular brown spots on the twigs, which later spread to shoots and leaves, causing the tea shoots to wilt and the leaves to curl and shrink, and eventually the whole branch to die. In this study, a strain was isolated and purified using the tissue isolation method. Combining the morphological characteristics with the phylogenetic analyses based on the sequences of the internal transcribed spacer regions (ITS), β-tubulin (TUB2), and the translation elongation factor1 alpha (TEF1-α), the isolated strain was identified as Botryosphaeria fusispora. Laboratory pathogenicity tests show that B. fusispora was the pathogen causing the twig wilting disease present on ‘Jiaming No. 1'. These results indicate that B. fusispora can be a new record species causing twig wilting on tea plants. In addition, mycelial growth inhibition tests were conducted to examine the sensitivity of the pathogen to three commercial fungicides, including chlorothalonil, thiophanate-methyl and pyraclostrobin. Among the tested fungicides, thiophanate-methyl was found to be the most effective in suppressing the radial growth of the strain, with an EC₅₀of 1.91 μg·mL^-1, followed by pyraclostrobin, with an EC₅₀of 2.25 μg·mL^-1.

Response of γ-Aminobutyric Acid Metabolic Pathway in Tea Plants to Early Infestation of Ectropis obliqua

SUN Juan, CHEN Hui, LIU Guanhua, ZHANG Han, HUANG Fuyin, WANG Yuxi, WANG Nuo, BAO Demeng, SHI Jiang, DAI Weidong, CHEN Jian, FU Jianyu

Journal of Tea Science. 2024, 44(5): 816-830. doi:10.13305/j.cnki.jts.2024.05.008

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Tea geometrid (Ectropis obliqua Prout) infestation induces tea plants to release massive amounts of volatile organic compounds (VOCs), which are widely reported as important chemical cues that either repel the pests or attract their enemies. However, the spatial variations and the roles of the non-volatile metabolites in tea leaves infested by the tea geometrids are confusing. Taking tea leaves as materials, the feeding of E. obliqua was limited at the leaf tip, and then the tissues at the leaf tip, middle and base were collected. The non-volatile metabolites of the tissues at the three sites were identified and analyzed by ultra-high performance liquid chromatography-quadrupole orbitrap mass spectrometry (UHPLC-Q-Exactive/MS). The results demonstrate that compared with the blank control and mechanical injury tea leaves, tea geometrids induced 11 differential metabolites, including six dimeric catechins, three amino acids (including γ-aminobutyric acid), one flavonoid and flavonoid glycoside, and one phenolic acid compound. After the infestation of the tea geometrids, the relative contents of γ-aminobutyric acid at the three sites in tea leaves were significantly increased compared to the blank control tea leaves, and increased by 1.99-fold in the middle and base of leaves. In addition, the key genes involved in the γ-aminobutyric acid biosynthetic pathway were upregulated at all three sites of tea leaves. There was a significant positive correlation between the relative content of γ-aminobutyric acid and the relative content of glutamic acid (P<0.05). When the tea geometrids were fed with artificial diet supplemented with 0.2 mg·g^-1, 0.5 mg·g^-1 and 2.0 mg·g^-1 γ-aminobutyric acid, their body weight and length were both significantly decreased compared with the control (P<0.05). The present study indicates that the inhibitory neurotransmitter γ-aminobutyric acid plays a pivotal role in the early defense response against tea geometrids, which will shed light on the biochemical resistance mechanism of the tea plants.

Simultaneous Determination of 27 Pyrrolizidine Alkaloids in Tea by Ultra-High Performance Liquid Chromatography-Tandem Mass Spectrometry with Integrated QuEChERS Purification

YAO Leijun, CHEN Yanqiu, LIN Hao, WANG Luyao, SHI Peiyu, ZHANG Yangyang, HUANG Ting, SONG Juan, WANG Yi, DAI Qin, LIU Chuan

Journal of Tea Science. 2024, 44(5): 831-842. doi:10.13305/j.cnki.jts.2024.05.005

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In this study, an integrated QuEChERS purification-ultra-performance liquid chromatography-tandem mass spectrometry method was established to detect 27 pyrrolizidine alkaloids (PAs) in tea, taking into account the residual risk of PAs in tea and the challenges of traditional QuEChERS. The method involves extracting the sample with 1% formic acid in acetonitrile, salting out using the centrifuge tube integrated salt bag and Down-Pressure QuEChERS Cleanup, detecting by multiple reaction monitoring mode (MRM), and quantifying it using the matrix-matched external standard method. The 27 PAs exhibit a strong linear relationship within their concentration ranges, with average recovery rates ranging from 73.0% to 111.8% and relative standard deviations from 1.6% to 13.8% (n=6). This method has the characteristics of simple operation, large detection throughput, high sensitivity, and reduction of repeated opening of the traditional QuEChERS, meeting the monitoring requirements for PAs in tea. During the actual testing of 60 batches of samples, different levels of PAs were detected in some tea samples, proving that there is indeed a risk of these plant toxins in tea, and continuous monitoring and tracking is recommended.

Analysis of the Differences in Physical and Chemical Indicators of Tea Product Quality Standards in China

LI Wenyan, ZHANG Lin, CHEN Liyan, ZHANG Yingbin, ZHOU Sujuan, HONG Yiwei, LIANG Sichen, SUN Hongfeng, CHEN Hongping

Journal of Tea Science. 2024, 44(5): 843-852. doi:10.13305/j.cnki.jts.2024.05.006

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Physical and chemical components, as the key substance of tea quality, to a certain extent determine the flavor, quality characteristics, and quality level of tea, thus becoming the key indicator of Chinese tea product standards. China has set up a variety of standards related to tea products, which have certain common characteristics and specificities. However, at present, there is little research on the physical and chemical indicator characteristics of Chinese tea product standards. We collected 227 national, industry, and local standards for tea and related products in China, including 20 physical and chemical indicators. Due to differences in origin, raw materials, processing technology and harvesting time, there is some variability in the requirements of physical and chemical indicators among different tea standards, but the direction of quality requirements is consistent. The number of green tea standards, as well as their physical and chemical index parameters are the most numerous and most demanding. The requirements of national standards for tea are generally lower than those of industry or local standards. Compared with national basic tea product standards, geographical indications for tea products are generally higher in terms of physical and chemical index requirements. This study provided a reference for the construction and improvement of the product quality standard system of tea products in China.

Analysis of the Regurgitation Effect of New Tea Beverage Consumption Intention on Traditional Tea Consumption

ZHANG Yi, HU Linying, YI Xiaoyun, CHEN Fuqiao, JIANG Aiqin

Journal of Tea Science. 2024, 44(5): 853-868. doi:10.13305/j.cnki.jts.2024.05.004

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To a certain extent, new tea beverage is the product of innovation and development based on traditional tea. China's long history of tea drinking provides a wide space for the new tea beverage market. The rich flavor of traditional tea as well as its inclusiveness become the main means of innovation for new tea beverage. Will new tea beverage consumption in turn affect traditional tea consumption? In this research, a theoretical model of new tea beverage consumption influencing traditional tea consumption was established, and the regurgitation mechanism was revealed. Then, using the new tea beverage research data from the Tea Research Institute of the Chinese Academy of Agricultural Sciences, it empirically examined the influence of new tea beverage consumption on traditional tea consumption. This research finds that there is a regurgitation effect of new tea beverage consumption on traditional tea consumption. The mechanism analysis shows that consuming new tea beverage can make consumers develop a traceability psychology and accumulate certain knowledge related to tea, thus promoting consumers' traditional tea consumption intention. The heterogeneity analysis shows that the effects of milk tea series and cheese-foam tea series are more prominent. Young groups with higher health consciousness are more likely to be influenced. The research conclusion helps to understand the ways of cultivating tea consumers through new tea beverage, and also has reference significance for expanding our country's tea consumption.

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