Study On Aroma Components Of Ten Types Of Fenghuang Dancong Tea

Fenghuang Dancong tea belongs to oolong tea,and it is the excellent single plant selected by the Fenghuang Narcissus variety,which has been picked individually and processed separately.Fenghuang Dancong tea enjoys high reputation for its special aroma of flower,fruit,honey,and is famous for ten fragrance types which are magnolia,honey orchid,cinnamon,almond,ginger flower,orchid,osmanthus,jasmine,yellow gardenia,cordate telosma.Aroma quality is an important factor affecting the flavor and price of Fenghuang Dancong tea.At present,although gas chromatography-mass spectrometry(GC-MS)has been used to analyze the aroma components of different fragrant Fenghuang Dancong tea,the research method is relatively simple.People can only analyze the types and contents of volatile components by GC-MS,but cannot determine the aroma-active compounds that play a key role in the aroma of tea.In this paper,GC-MS,chromatography-olfactometry(GC-O),gas chromatography(GC)external standard method,sensory evaluation and quantitative description analysis(QDA)were combined to analyze the aroma components of ten fragrance types of Fenghuang Dancong tea.This study aimed to clarify the main volatile constituents and aroma-active compounds,and explore the differences of aroma of Fenghuang Dancong tea.By aroma recombination test,these important aroma compounds contributing to the most typical Fenghuang Dancong tea were verified.This paper provides the reference for the further study on the classification of fragrance types of Fenghuang Dancong tea.The main research contents and results were presented as follows:1,The volatile components of ten fragrance types of Fenghuang Dancong tea were extracted using solvent assisted flavor evaporation(SAFE),and then analyzed by GC-MS.A total of 122 volatile components were identified,including 29 hydrocarbons,26 alcohols,23 esters,15 ketones,11 aldehydes,5 lactones,5 ethers,5 acids,1 phenols and 2 nitrogenous heterocyclic compounds.Among them,the types and contents of hydrocarbons,alcohols,ketones and esters were the most abundant.All the tea samples contained 29 common components,among them,the contents of dihydroactinidiolide,nerolidol,epoxylinalool,methyl hexadecanoate,hexanal,?-ionone,linalool oxide I were higher.The compositions and contents of volatile compounds of ten fragrance types of Fenghuang Dancong tea had certain regularity,but there were still significantdifferences among all tea samples.The results showed that different fragrance types had content differences on the common components,and each also had its characteristic components.2,Based on the results of volatile components identified by GC-MS,the similarity rates of ten fragrance types of Fenghuang Dancong tea were compared,and the cluster analysis(CA)were done.Results showed that the volatile components of jasmine fragrance was the most similar to yellow gardenia fragrance,while cordate telosma fragrance had obvious differences to other fragrance types.Principal components analysis(PCA)was used to analyze volatile components.It was found that the cumulative variance contribution rate of the first 6 principal components reached 82.79%,which could basically explain the variable information of the aroma of Fenghuang Dancong tea.The characteristic volatile components obtained by the PCA were isophorone,?-caryophyllene,decanal,methyl myristate,cyclohexanone,?-pinene,linalool oxide I,epoxylinalool,cis-3-hexenyl 2-methylbutanoate,(Z)-3-decenol,indole,(Z)-3-hexenyl hexanoate,hexyl hexanoate,nerolidol,2-isopropyl-5-methyl-2-hexenal,cyclooctanone,1-nonanol,?-ionone,?-terpinene,ocimene,nerol oxide,dihydro-?-ionone,?-ionone.The comprehensive score evaluation model based on PCA was in good agreement with the results of aroma sensory evaluation.3,By GC-O analysis,36 aroma-active compounds were perceived from ten fragrance types of Fenghuang Dancong tea.The fragrance of flower,sweet aroma,fruity flavor and refreshing fragrance were the major aroma categories.33 aroma-active compounds were identified,including 9 alcohols,4 hydrocarbons,6 ketones,6 esters,2lactone,4 aldehydes,1 acids and 1 nitrogenous heterocyclic compounds,and the other 3unknowns need to be further studied.Nerolidol and linalool were main aroma components in ten tea samples,which also displayed the fragrance of flower,fruit and honey.It can be inferred that nerolidol and linalool have an important contribution to the formation of the aroma of Fenghuang Dancong tea.4,The aroma recombination models of the osmanthus fragrant and the yellow gardenia fragrant Fenghuang Dancong tea were determined based on the identification results of strength method by GC-O and quantitative results of external standard method by GC.Through QDA of tea infusions and recombinant models,it was found that the intensity of osmanthus aroma and honey were the highest among the 8 characteristic aroma properties in tea infusion of osmanthus fragrant Fenghuang Dancong tea,while the intensity of sweet and gardenia aroma were the highest in tea infusion of yellowgardenia fragrant Fenghuang Dancong tea.The recombination models of two fragrance types of Fenghuang Dancong tea were basically consistent with the aroma outlines of the original tea infusions,which can effectively verify the identification results of GC-O.