| Oolong tea is a tea with Chinese characteristics,known for its high flavor and strong flavor.The new line "606"(Yuqiong)was bred from the single-breeding method of the natural hybrid offspring of Huang Dan.The picking period is early,and the tree body is suitable for machine picking.Its oolong camellia fragrance is long and lasting,the taste is fresh and mellow,the water fragrance is obvious,and the quality style is unique.In this study,the new strain(606)was taken as the research object,and Huang Dan as the control variety.The basic biochemical components,main flavor metabolites,main volatile components,and sensory qualities in the processing of the two varieties of oolong tea were measured and analyzed.Variation trends and flavor differences and characteristics of flavor components and volatile components during the processing of strain "606" and Huangdan Oolong tea;further analysis and analysis of the dynamic changes in the relative expression of flavonoid O-methyltransferase(FOMT)gene in the flavonoid pathway during processing to further reveal the flavor components of Oolong tea The molecular mechanism and differences.Provide theory and application basis for quality research,characteristic analysis and popularization of new oolong tea strains.The main findings are as follows:1.Study on the changes of basic biochemical components in the processing of new strain "606" and Huangdan Oolong teaThe new strain "606" and Huangdan oolong tea have similar changes in the main biochemical components.The new strain "606" and Huangdan have little difference in the water extract of fresh leaves,but the processed tea is 11.21% higher than Huangdan The tea polyphenol content and phenol-ammonia ratio of the new strain "606" are significantly higher than that of the Huangdan variety during the processing,the flavonoid content is mostly higher than the Huangdan,and the amino acid content is mostly lower than the Huangdan;the tea yellow during processing The growth rate of vegan,thearubin,and theaflavin is significant.The new strain "606" has a greater growth rate than Huang Dan;the caffeine content of the two varieties during the processing is relatively stable,with little change.The biochemical characteristics of the new strain "606" Maocha:water extracts,tea polyphenols,and flavonoids are significantly higher than those of Huang Dan,and the content of amino acids and caffeine is basically the same.Sensory quality characteristics show that the new strain "606" has tight knots,dark brown oily,delicate and long-lasting aroma,fresh and mellow taste,rich taste,more watery fragrance,bright orange soup,soft and bright leaf base Qi,with a high yield rate;and Huang Dan’s ties are tighter and more mellow,with a long-lasting aroma,rich flavor and mellow taste,the soup color is orange and bright,the leaf base is thicker and softer,more uniform;the new strain "606" and yellow Dandan is a high-scent variety,but the new strain "606" is slightly higher in appearance,aroma,taste,and leaf bottom score than the Huangdan variety.The rich content of the new strain "606" Maocha is consistent with the richer and more refreshing taste characteristics in the sensory evaluation,and is characterized by a long-lasting fragrance and a fresh and mellow flavor.2.Study on the dynamic changes of taste components during the processing of the new strain "606" oolong teaIn this study,by ultra-high performance liquid chromatography-triple quadrupole tandem mass spectrometry(UPLC-Qq Q MS)targeted metabolomics research methods,the new strain "606" processing samples and Huangdan Mao tea amino acid,catechins,The determination of caffeine,theaflavins,rutin and other components showed that: during the processing of the new strain "606",the fresh,sweet,and sour amino acids,EGCG3 "Me,and rutin showed a" decrease-rise-decrease " Change law;bitter taste,aromatic amino acids,caffeine showed a "first rise and then fall" change;while ester catechins and non-ester catechins showed a continuous decline,theaflavins components TF3 and TF1 The content is generally on the rise.The new strain "606" and Huangdan Maocha were compared andanalyzed.The results showed that the specific content of the flavored amino acids of the two varieties was different.The new strain "606" and Huangdan’s fresh,sweet,sour,The bitter amino acids have very significant differences,while the aromatic amino acids of the two have no significant differences.The fresh amino acids of Huang Dan are 17.78%higher than that of the new strain "606".The amino acids of the sweet,sour,bitter,and aromatic amino acids of the new strain "606" are higher than those of Huang Dan,respectively 52.38% and 27.34%.62.5%,64.44%.It shows that the taste is rich and diverse.The EGCG3 "Me content of the new strain" 606 "and Huang Dan is very significantly different.The EGCG3" Me content of the new strain"606" is 7.99 mg/g,1.1 mg/g for Huang Dan,and the new strain "606" is yellow Once 6.26 times,it may be the oolong tea strain with high EGCG3"Me content.The content of non-ester catechins and rutin in Huang Dan was significantly higher than that in the new strain "606",and the caffeine content in the new strain "606" was significantly higher than that in Huang Dan.The ester catechins and tea yellow of the two varieties There were no significant differences in the contents of the TF1 and TF3 components.3.Study on the dynamic changes of volatile components during the processing of the new strain "606" Wulong teaThe headspace solid-phase microextraction method combined with gas chromatography-time-of-flight mass spectrometry(HS-SPME-GCTOF-MS)was used to analyze and analyze the volatile components in the processing samples of the new strain "606" Oolong tea.The results showed that during the processing of the new strain "606",there were less volatile components in the fresh leaves and withered leaves,making geraniol,jasmone,α-farnesene,nerol,indigo in green leaves The formation and increase of important volatile components such as indole;31 main volatile components were identified during the entire process,which belonged to alcohols,ketones,aldehydes,ester compounds and nitrogen-containing compounds,hydrocarbons,and heterooxy compounds.7 types,of which esters and alcohols are the main types.The main component analysis results show that although the new strain "606" oolong tea has the floral and fruity characteristic volatile components such as α-farnesene,geraniol,phenylethanol,indole,linalool and their oxides,but its The content of tert-ol in neroli is relatively low,while the content of ester-type compounds with clear fruit aroma such as phyllohexanoate is higher.HS-SPME-GC-TOF-MS was used to measure and analyze the volatile components of Huangdan and new strain "606" Maocha.The results show that the main volatile components of Huangdan Maocha are indole,trans-nerol,4-hexene caproate,cis-tetrahydro-6-(2-pentenyl)-2H-2-Pyrone,phenylethanol,valeric acid,2,3-dihydro-3,5dihydroxy-6-methyl-4(H)-pyran-4-one,nerol,benzonitrile,etc.Mainly contains nitrogen compounds,alcohol compounds,ester compounds,ketone compounds,and has more acid compounds;and the main volatile components of the new series of "606" Maocha are leaf alcohol caproate,α-Farnesene,linalool,geraniol,phenylethanol,benzyl alcohol,etc.The volatile types are mainly ester compounds,alcohol compounds,hydrocarbons,etc.The new line "606" as a descendant of Huang Dan,the main volatile components of both are alcohols and ester compounds,both have α-farnesene,geraniol,phenylethanol,indole,etc.Volatiles,but the components and types of the two are different: the new line "606" is mainly composed of ester compounds and hydrocarbons with a clear fruit fragrance,while Huang Dan is composed of nitrogenous compounds and ketones with a floral fragrance The main type compounds,and Huang Dan has more acid compounds;the new line "606" has a low content of nerol(with floral fragrance),and its characteristic component,folic acid caproate(with clear fruit fragrance)is in It is rarely detected in Huang Dan,and the content of ester compounds of the new strain "606" with clear fruit fragrance is 67.08% higher than that of Huang Dan.In summary,the volatile components of the new line "606" are different from those of other floral and fruity varieties of oolong tea,which may be the reason for its unique variety flavor.4.Study on quantitative expression changes of FOMT gene in the processing of new strain "606" and Huangdan Oolong teaBased on ultra-high performance liquid chromatography-triple quadrupole tandem mass spectrometry(UPLC-Qq Q MS)targeted metabolism,the new strain "606" has a high content of EGCG3 "Me(methylated catechins),and EGCG3" Me belongs to the genus Flavonoid compounds may be O-methylated substances in the flavonoid pathway,while flavonoid O-methylation in plants is catalyzed by flavonoid O-methyltransferase(FOMT).In order to further reveal the molecular mechanism of the taste components of the new oolong tea strains,q PCR quantitative analysis of the relative expression levels of fresh leaves of the new strain "606" and Huang Dan and the FOMT genes(FOMT1,FOMT2,FOMT3)during processing was carried out.The relative expression levels of the three FOMT genes in the processing of the new strain "606" showed an overall "up-down" fluctuation trend.FOMT1 and FOMT2 reached the highest value in the five-leaved leaves,the expression levels were 6.08 and 4.38,respectively,and the lowest value in the fresh leaf stage.The relative expression of the five-leaved leaves was significantly higher than that in the fresh leaves.FOMT3 reached the highest value of 6.14 in the withered leaves,and reached the lowest value of 0.19 in the three leaves.The relative expression of the withered leaves was significantly higher than that of the fresh leaves,and the three leaveswere significantly lower than the fresh leaves.The relative expression level of FOMT gene showed an overall downward trend.The highest values of FOMT1,FOMT2 and FOMT3 are in the fresh leaf stage(expression level is 1.00),the lowest value is the green leaf,the relative expression levels of withered leaves,one shake leaf,three shake leaves,six shake leaves and green leaves are all very significantly lower than fresh leaves.The expression of FOMT gene in the processing of the new strain "606" was basically higher than the quantitative expression in the processing of Huang Dan.The relationship between the quantitative expression of FOMT1,FOMT2 and FOMT3 genes and the content of EGCG3 "Me in the processing of the new line" 606 "is: the relative expression of FOMT1,FOMT2 and FOMT3 genes in the fresh leaf-withered leaf stage increased,and the expression of FOMT3 gene increased significantly The content of EGCG3 " Me decreased significantly;the relative expression of FOMT1 gene increased during the withered leaf-green leaf stage,the relative expression of FOMT2 and FOMT3 genes and the content of EGCG3 " Me decreased;the content of EGCG3 " Me was highly negatively correlated with FOMT1 gene.It has a moderate negative correlation with the FOMT2 gene and a low negative correlation with the FOMT3 gene. |
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