Browse by section

    Content of SPECIAL FOCUS: TEA in our journal
        Published in last 1 year |  In last 2 years |  In last 3 years |  All
    Please wait a minute...
    For Selected: Toggle Thumbnails
    Effects of LED Light Withering at Different Temperatures on Expression of Key Genes in the Upstream of MEP and Formation of Volatiles in Tieguanyin Tea
    YOU FangNing,DENG HuiLi,HU Juan,YAO ZhiLing,WU ShuaiQiang,QIN YiJia,TANG TongHua,SUN Yun
    Scientia Agricultura Sinica    2020, 53 (2): 346-356.   DOI: 10.3864/j.issn.0578-1752.2020.02.009
    Abstract249)   HTML11)    PDF (515KB)(188)       Save

    【Objective】Terpenoids are important aroma components of oolong tea, and the key upstream genes of the MEP are directly involved in the regulation of the synthesis of terpenoid precursors. Withering, a process closely related to the aroma formation of oolong tea, is affected by many factors such as light exposure and temperature. The present study was aimed at investigating the effects of LED light and temperature on the aroma formation of oolong tea during withering process and to provide reference for improving aroma quality of withered leaves of Oolong tea. 【Method】 Firstly, the key upstream genes of MEP (DXS, DXR, HDS, and HDR) in tea which responded to light were selected according to our previous transcriptome data and KEGG pathways. The tea cultivar Tieguanyin was chosen as test materials, which were plucked in Tea Science Teaching and Research Base of Fujian Agriculture and Forestry University with one bud and three leaves. The freshly plucked leaves were treated under white LED light coupling with series temperature ((20℃ (L20), 25℃ (L25), 30℃ (L30), 35℃ (L35) and 40℃ (L40) ), Dark treatment (20℃ (D20), 25℃ (D25), 30℃ (D30), 35℃ (D35), and 40℃ (D40) ), and then the aroma contents and key upstream gene of MEP of withered leaves were determined.【Result】Under L30 treatment, DXS, DXR, HDS and HDR genes in the withered leaves were reached maximum, and which was 4.31, 5.28, 11.77, and 1.59 fold of XY (CK), respectively; these genes in L30 were 2.24, 2.39, 1.86 and 1.60 fold compared to D30 treatment; these genes expression were highest in D30 among Dark group and was 1.92, 2.21, 6.34 and 0.99 fold of XY, respectively. The contents of α-Farnesene and Linalool oxide (I, II) of L20 was the highest, which were increased by 15.05%, 4.92% and 15.13%, respectively, compared to XY. The highest content of Nerolidol, Linalool and Geraniol were occurred in L30 treatment, which were increased by 3.71%, 6.14% and 15.28%, respectively, compared with XY. The content of main aroma components in the LED group of Tieguanyin withered leaves was higher than that of temperature group. The mathematical model was established by principal component analysis method and the aroma components of the withered leaves were evaluated. It was found that the L20 treatment had the highest score and followed by L30, which were consistent with the aroma analysis. 【Conclusion】According to the comprehensive test results, there was no synchronization between the expression of the genes and the aroma contents of Tieguanyin, The gene expression under L30 treatment, aroma contents and principal component analysis scores were higher than that under other treatments. These results were consistent with the withering temperature in Tieguanyin production: when withering temperature was too high (40℃), the related gene expression and the formation of terpenoids in the withered leaves were prohibited.

    Table and Figures | Reference | Related Articles | Metrics
    Metabolic Changes in the Processing of Yunkang 10 Sun-Dried Green Tea based on Metabolomics
    DAI YuQiao,Lü CaiYou,HE LuNan,YI Chao,LIU XueYan,HUANG Wen,CHEN JiaMin
    Scientia Agricultura Sinica    2020, 53 (2): 357-370.   DOI: 10.3864/j.issn.0578-1752.2020.02.010
    Abstract352)   HTML13)    PDF (3096KB)(361)       Save

    【Objective】The ultrahigh phase liquid chromatography/mass spectrometry (LC-MS) combined technique of metabolomics was used to explore the changes of metabolites in the processing of sun-dried green tea of Camellia sinenis var. assamica cv. Yunkang 10, and to find the iconic metabolites affecting the formation of sun-dried green tea quality. Further study on the change path of these substances would lay a foundation for understanding the formation mechanism of sun-dried green tea quality. 【Method】In the process of making Yunkang 10 sun-dried green tea, 3 samples of fresh leaves, rolled leaves and sun-dried leaves were taken respectively. After the samples were pretreated, the metabolites in the three groups of samples were detected by LC-MS and identified by mass spectrometry database. Principal component analysis (PCA) and partial least squares discriminant analysis (PLS-DA) were used to analyze the detection data of three groups of samples. Metabolites with significant differences were screened out by PLS-DA method. 【Result】LC-MS analysis method for the endogenous metabolites of Yunkang 10 fresh leaves, rolled leaves and sun-dried leaves was established, and commercial mass spectrometry database was used for rapid identification of the detected metabolites. The metabolome data were imported into SIMCA-P software for principal component analysis and partial least squares discriminant analysis, and the metabolome data could be used to distinguish the three groups of samples. By LC/MS technique on Yunkang 10 sun-dried green tea and its processing tea, in combination with multivariate statistical analysis, there were 701 kinds of metabolites were significant differences among the fresh leaves, rolling leaves and sun-dried leaves, and 116 kinds metabolites between fresh leaves and rolling leaves, 158 kinds of metabolites between sun-dried leaves and fresh leaves, and 48 kinds of metabolites between sun-dried leaves and rolling leaves were found. By searching KEGG database to analyze metabolites, these metabolites were mainly related to amino acid metabolism, polyphenol metabolism and other energy metabolism pathways. 【Conclusion】LC-MS technique could be used to distinguish fresh leaf group, rolled leaf group and sun-dried leaf group of Yunkang 10, which proved that metabolomics technology could reveal the chemical changes of metabolites in sun-dried green tea to some extent. The key metabolites were found in the study could provide a theoretical basis for evaluating the quality of sun-dried green tea, and lay a theoretical foundation for exploring the formation of "sunburn taste" of sun-dried green tea and the formation mechanism of sun-dried green tea quality.

    Table and Figures | Reference | Related Articles | Metrics
    Typical Yellow Tea Taste Characteristic and Its Related Taste-Chemical Compositions
    FAN FangYuan,TANG GuiZhen,GONG ShuYing,ZONG BangZheng,GUO HaoWei,LI ChunLin
    Scientia Agricultura Sinica    2020, 53 (2): 371-382.   DOI: 10.3864/j.issn.0578-1752.2020.02.011
    Abstract363)   HTML49)    PDF (3631KB)(358)       Save

    【Objective】Yellow tea is a unique Chinese traditional tea, which has a special taste characteristic produced by a unique processing step, namely “sealed yellowing”. Studies about the associations of yellow tea taste characteristic attributes and their related chemical compositions would create the conditions for elucidating the chemical-acting mechanism of formation of yellow tea taste characteristic. Meanwhile, it would provide important evidence for standardization production of yellow tea. 【Method】 In this study, the taste characteristic attributes of yellow teas from China traditional yellow-tea producing areas and their related taste-chemical compositions were explored by sensory evaluation, chemical detection and chemometrics analysis 【Result】This research showed that mellow taste and sweet taste were the common characteristic attributes of yellow teas. It had different performance of umami, thickness, astringency and coarse taste in yellow teas from different tea producing areas. There were significant differences on the content of taste chemical compositions among yellow teas from different tea producing areas. In this study, the correlation was closer between thickness and astringency. The coarse taste attribute was an important contributor to separating Anhui yellow big tea from other types of yellow teas, which was due to the lower tenderness of fresh leave materials. The correlation analysis showed that gallic acid, gallic acid/flavone ratio (GA/Fla), gallic acid/catechins ratio (GA/Ca) and gallic acid/alkaloids ratio (GA/Alk) had a high correlation with coarse taste characteristic, which presumably was due to the high content of gallic acid in the yellow tea made from mature leaves under the experimental conditions. Amino acids are the important contributors for the umami taste in yellow teas, especially like glutamic acid, theanine/amino acids ratio (Thea/aa) and umami/total amino acids ratio (Umami/aa) under this experimental condition. 【Conclusion】 The mellow and sweet taste attributes were the taste characteristic common attributes of yellow teas. The coarse taste was typical taste characteristic attribute of yellow big teas. In this study, the gallic acid, GA/Fla, GA/Ca and GA/Alk were closely relation with coarse taste based on the characteristics of these experimental samples, and the glutamic acid, Thea/aa, Umami/aa were highly correlated with umami taste in yellow teas.

    Table and Figures | Reference | Related Articles | Metrics
    Taste Characteristic and Main Contributing Compounds of Different Origin Black tea
    SONG ChuJun,FAN FangYuan,GONG ShuYing,GUO HaoWei,LI ChunLin,ZONG BangZheng
    Scientia Agricultura Sinica    2020, 53 (2): 383-394.   DOI: 10.3864/j.issn.0578-1752.2020.02.012
    Abstract817)   HTML40)    PDF (2487KB)(571)       Save

    【Objective】 This study focused on the taste characteristic of typical black tea from main black tea producing areas in China. The important taste compounds of black tea were detected, and the correlation between the main contributing compounds and the taste characteristic of black tea was analyzed. 【Method】 In this study, the black tea samples were collected from Shandong, Hubei, Anhui, Henan, Zhejiang, Hunan, Fujian, Guizhou, Sichuan and Yunnan, named by Shandong Linyi black tea, Hubei Hongan black tea, Anhui Qimen black tea, Henan Xinyang black tea, Zhejiang Shaoxing black tea, Hunan Guzhang black tea, Fujian Wuyishan black tea, Guizhou Puan black tea, Sichuan Yaan black tea and Yunnan Fengqing black tea, respectively. The taste characteristic of black teas were analyzed and compared by sensory evaluation according national standard. High performance liquid chromatography (HPLC) and ultrahigh performance liquid chromatography-mass spectrometry (UPLC-MS) were used for the determination of 65 compounds including catechins, alkaiods, flavonoids, amino acids and gallic acid, sugars and organic acids. The correlation between the compounds and the taste characteristic of black teas were analyzed by principal component analysis (PCA) based on IBM SPSS Statistics 25. 【Result】 There were obvious difference on taste characteristic of black teas from 10 tea producing areas in China. Black teas from Yunnan and Guizhou were belong to large leaf teas, which were considered by the taste of mellow, thick, and umami, while the taste characteristic of black teas from other 8 tea producing areas were mainly reflected in fresh and umami. The PCA results showed that the taste constituents directly were responsible for discrimination of black teas from different sources. The clear separation of large-leaf black teas from small leaf-black teas could be found based on PC1. Black teas with taste characteristic of fresh and umami could be divided into two categories based on PC2, among which Shandong Linyi black tea, Anhui Qimen black tea and Zhejiang Shaoxing black tea with more fresh taste scored higher. According to the loading plot of principal component analysis, fumaric acid, total catechins, Myr-3-O-glu, theophylline, theobromine and theaflavins with high scores on the positive of PC1, two kaempferol triglucosides and total flavonol glycosides with high scores on the negative of PC1 and most of the free amino acids with high scores on the positive of PC2, were presumed to make important contribution for classification of geological black teas. Further chemical content analysis showed that the content of fumaric acid, total catechins, Myr-3-O-glu, theophylline, theobromine and theaflavins in large-leaf black teas were higher than that in other samples, with average value of about 7.6, 554, 1.3, 7.9, 205, and 15 μg?mL -1, respectively. Conversely, the contents of two kaempferol triglucosides and total flavonol glycosides were higher in small-leaf black teas than that in the big-leaf ones. Hubei Hongan black tea had the highest amounts of total flavonol glycosides, up to 80 μg?mL -1, which was four times as much as that in large leaf black teas. Black tea numbered 1, 3, and 5 had strong umami taste characteristic based on sensory evaluation, in which the content of free amino acids reached 300 μg?mL -1. 【Conclusion】 In conclusion, there were significant differences in the taste characteristic of 10 representative black tea producing areas in China. The taste characteristic of large-leaf black teas was mellow, thick and umami, while that of small-leaf black teas was fresh and umami. Alkaloids, organic acids, catechins and its oxides were the important contributors for taste characteristic of mellow and thick in black teas. The taste characteristic of fresh and umami in black teas maybe caused by free amino acids.

    Table and Figures | Reference | Related Articles | Metrics
      First page | Prev page | Next page | Last page Page 1 of 1, 4 records