In the postharvest processing of tea leaves,withering is the first indispensable manufacturing process which produces the mellow,umami and sweet taste of white tea.In this study,we aimed to determine the dynamic chang...In the postharvest processing of tea leaves,withering is the first indispensable manufacturing process which produces the mellow,umami and sweet taste of white tea.In this study,we aimed to determine the dynamic changes of the main metabolites and clarify the key differentially expressed genes(DEGs) involved in forming the characteristic taste of white tea during withering.Phytochemical analyses revealed that the contents of total catechins and starch decreased continuously,whereas the contents of theaflavin,γ-aminobutyric acid(GABA),maltose,and soluble sugars increased significantly during withering(from 0–48 h).Meanwhile,the elevation of α-amylase(AMY),β-amylase(BAM),total amylase,and glutamate decarboxylase(GAD) activities may be correlated with the accumulation of GABA and maltose.By transcriptome sequencing,we detected 9 707,15 921,17 353,and 17 538 DEGs at 12,24,36,and 48 h of the withering process,respectively,compared with 0 h sample(fresh leaves).The transcript levels of most of the DEGs involved in catechin biosynthesis were significantly inhibited,whereas those involved in catechin oxidation were significantly up-regulated,which could be correlated to a decrease in catechin content and an increase in theaflavin content.The DEGs involved in GABA biosynthesis were considerably up-regulated,and the down-regulation of SPMS could reduce the competition for converting spermidine to GABA.The up-regulation of the AMY and BAM genes could trigger starch degradation,resulting in the increase of soluble sugar content.These results provide new insights into the importance of the withering process to the characteristic taste of white tea.展开更多
Tea’s popularity and flavor are influenced by factors like cultivation and processing methods and shaping techniques also have an impact on tea flavor.This study employed targeted metabolomics and chemometrics to inv...Tea’s popularity and flavor are influenced by factors like cultivation and processing methods and shaping techniques also have an impact on tea flavor.This study employed targeted metabolomics and chemometrics to investigate how shaping techniques affect the flavor of milk-flavored white tea(MFWT).The results showed that the tea cake sample with the shortest pressing time(Y90)has the highest amino acid content and milky aroma intensity.There were variations in amino acids,catechins,and soluble sugars among MFWT samples with different shaping techniques.The total contents of amino acids and catechins in tea cake sample(Y90)were significantly lower than those in the loose tea sample(SC)and bundle-like tea sample(SG),while the total sugar content was significantly higher than that in SC(P<0.05).Additionally,the content of volatiles presenting milky aroma(VIP&OAV>1)in Y90 remained lower relative to SC and SG(P<0.05),but the proportion was not different from that in SC and SG,minimally affecting the overall flavor.The short-time pressing method might be suitable for mass production of MFWT.These findings provide insights into improving the tightness of the appearance of MFWT with minimal impact on tea flavor.展开更多
[Objective] The biological safety of white insect tea in Xifeng County of Guizhou Province was evaluated in order to provide a scientific basis for the development of white insect tea. [Method] Acute toxicity test in ...[Objective] The biological safety of white insect tea in Xifeng County of Guizhou Province was evaluated in order to provide a scientific basis for the development of white insect tea. [Method] Acute toxicity test in mice, Ames microbiological test and mouse bone marrow polychromatic erythrocyte micronucleus test were done with wild white inset tea produced in Xifeng County. At the same time, the contents of six kinds of limit pollutants were determined, including Pb,Cr,Cd,Hg,As,and F-. [Result] The results showed that white insect tea had LD505.0 g/kg（BW）in acute toxicity test, negative response in Ames test and microkernel test. In addition, the contents of Pb,Cr,Cd,Hg,As,and F- in the white inset tea were 2.20,1.06,0.46,0.09,0.71,21.50 mg/kg, much less than the national standard of tea （GB2762-2005,NY 659-2003）. [Conclusion] The white insect tea produced in Xifeng County of Guizhou Province is non-toxic, and good for human as beverage.展开更多
基金supported by the China Agriculture Research System of MOF and MARA (CARS-19)the Scientific Research Foundation of Graduate School of Fujian Agriculture and Forestry University, China (102–1122YS010)+6 种基金the Rural Revitalization Tea Industry Technical Service Project of Fujian Agriculture and Forestry University, China (11899170145)the “Double First-class” Scientific and Technological Innovation Capacity and Enhancement Cultivation Plan of Fujian Agriculture and Forestry University, China (KSYLP004)6.18 Tea Industry Technology Branch of Collaborative Innovation Institute, China (K1520001A)the Fujian Agriculture and Forestry University Construction Project for Technological Innovation and Service System of Tea Industry Chain, China (K1520005A01)the Construction of Plateau Discipline of Fujian Province, China (102/71201801101)the Biochemical Analysis and Biological Study of Tea Plant Germplasm Resources of Fujian Agriculture and Forestry University, China (K1518023A)the Innovation Training Program for College Students of Fujian Agriculture and Forestry University, China (102–111ZC20061)。
文摘In the postharvest processing of tea leaves,withering is the first indispensable manufacturing process which produces the mellow,umami and sweet taste of white tea.In this study,we aimed to determine the dynamic changes of the main metabolites and clarify the key differentially expressed genes(DEGs) involved in forming the characteristic taste of white tea during withering.Phytochemical analyses revealed that the contents of total catechins and starch decreased continuously,whereas the contents of theaflavin,γ-aminobutyric acid(GABA),maltose,and soluble sugars increased significantly during withering(from 0–48 h).Meanwhile,the elevation of α-amylase(AMY),β-amylase(BAM),total amylase,and glutamate decarboxylase(GAD) activities may be correlated with the accumulation of GABA and maltose.By transcriptome sequencing,we detected 9 707,15 921,17 353,and 17 538 DEGs at 12,24,36,and 48 h of the withering process,respectively,compared with 0 h sample(fresh leaves).The transcript levels of most of the DEGs involved in catechin biosynthesis were significantly inhibited,whereas those involved in catechin oxidation were significantly up-regulated,which could be correlated to a decrease in catechin content and an increase in theaflavin content.The DEGs involved in GABA biosynthesis were considerably up-regulated,and the down-regulation of SPMS could reduce the competition for converting spermidine to GABA.The up-regulation of the AMY and BAM genes could trigger starch degradation,resulting in the increase of soluble sugar content.These results provide new insights into the importance of the withering process to the characteristic taste of white tea.
基金support from the National Key Research and Development Program of China(2022YFD2101101)the Modern Agricultural(Tea)Industry Technology System of Fujian Province,China([2021]No.90)+2 种基金the Guiding Project of Science and Technology Department in Fujian Province,China(2022N0031)the Special Fund Program for Science and Technology Innovation of Fujian Agriculture and Forestry University,China(KFB23203)the Special Fund for Science and Technology Innovation of Fujian Zhang Tianfu Tea Development Foundation,China(FJZTF01)。
文摘Tea’s popularity and flavor are influenced by factors like cultivation and processing methods and shaping techniques also have an impact on tea flavor.This study employed targeted metabolomics and chemometrics to investigate how shaping techniques affect the flavor of milk-flavored white tea(MFWT).The results showed that the tea cake sample with the shortest pressing time(Y90)has the highest amino acid content and milky aroma intensity.There were variations in amino acids,catechins,and soluble sugars among MFWT samples with different shaping techniques.The total contents of amino acids and catechins in tea cake sample(Y90)were significantly lower than those in the loose tea sample(SC)and bundle-like tea sample(SG),while the total sugar content was significantly higher than that in SC(P<0.05).Additionally,the content of volatiles presenting milky aroma(VIP&OAV>1)in Y90 remained lower relative to SC and SG(P<0.05),but the proportion was not different from that in SC and SG,minimally affecting the overall flavor.The short-time pressing method might be suitable for mass production of MFWT.These findings provide insights into improving the tightness of the appearance of MFWT with minimal impact on tea flavor.
基金Supported by Science and Technology Foundation of Guizhou Province(LKS[2009]No.24)Technological Innovation Team-building Projects of Guizhou Province([2009]4007)~~
文摘[Objective] The biological safety of white insect tea in Xifeng County of Guizhou Province was evaluated in order to provide a scientific basis for the development of white insect tea. [Method] Acute toxicity test in mice, Ames microbiological test and mouse bone marrow polychromatic erythrocyte micronucleus test were done with wild white inset tea produced in Xifeng County. At the same time, the contents of six kinds of limit pollutants were determined, including Pb,Cr,Cd,Hg,As,and F-. [Result] The results showed that white insect tea had LD505.0 g/kg（BW）in acute toxicity test, negative response in Ames test and microkernel test. In addition, the contents of Pb,Cr,Cd,Hg,As,and F- in the white inset tea were 2.20,1.06,0.46,0.09,0.71,21.50 mg/kg, much less than the national standard of tea （GB2762-2005,NY 659-2003）. [Conclusion] The white insect tea produced in Xifeng County of Guizhou Province is non-toxic, and good for human as beverage.
