Analysis Of Main Characteristic Flavor Components Of Cyclocarya Paliurus Tea

Cyclocarya paliurus(Batal.)Iljinskaja is a dicotyledonous plant,Juglandaceae,and genus of Cyclocarya paliurus.It has the functions of lowering blood sugar,pressure and fat.Since October30,2013,the National Health Commission of the People's Republic of China approves Cyclocarya paliurus'leaves as a new food ingredient,and stipulated that its consumption method is“brewing”.However the flavor of Cyclocarya paliurus tea on the market is quite different.In order to study and evaluate the flavor of Cyclocarya paliurus tea more objectively,this study chose modern instrument detection methods combine with human senses,using different statistical analysis methods to research on the flavor substances of Cyclocarya paliurus tea.The main results were as follows:1)The volatile substances of Cyclocarya paliurus tea was extracted by simultaneous distillation extraction(SDE)and solid phase microextraction(SPME).To compare with the SDE method,the SPME method can adsorb more volatile substances in the leaves,and the adsorption amount is large.The optimal extraction conditions for SPME are:chose the extraction head was75?m CAR/PDMS,the extraction temperature was 80°C,the extraction time was 60 min and the tea to water ratio(mass ratio)was 1:15.Under the optimal extraction conditions,the volatile substances of Cyclocarya paliurus tea were identified by gas chromatography with high-throughput time-of-flight mass spectrometry(GC-TOF-MS).The total volatile substances were229,including 36 kinds of esters(4.66%),33 kinds of aldehydes(38.42%),34 kinds of olefins(18.35%),26 kinds of alkanes(3.00%),20 kinds of alcohols(11.81%),16 kinds of ketones(6.43%),3 kinds of acids(0.21%),61 kinds of nitrogen-containing sulfur and heterocyclic compounds(8.16%).2)Under the optimal extraction conditions,the samples of Cyclocarya paliurus tea from different producing areas were analyzed by SPME-GC-TOF-MS technique to identify the volatile substances and establish fingerprints.The similarity and overlap rate of chromatographic peaks in different samples were higher,but they were also slightly different.According to the difference of volatile substance types and content of different samples,cluster analysis(HCA)was carried out to visually divide all tea samples into four categories.Which indicated that there are significant differences in the types and contents of volatile substances from different samples.The total 19kinds of 100%shared peaks were obtained from the chromatograms of all the samples.The PCA analysis were extracted out 5 principal components,and the cumulative contribution rate reached91.04%.Among them,decanal,heptaldehyde,(E,E)-2,4-heptadienal and nonanal were high content in samples,which contributed a lot to the aroma of tea samples.Pterocarya stenoptera C.DC a common adulterates material of Cyclocarya paliurus tea which results of GC-TOF-MS were compared.It was found that the volatile substances of the two are significantly different in type and content.Although there were 41 kinds of common peaks with Cyclocarya paliurus tea,the content and ratio were significantly different,especially the substances with characteristic aroma:hexaldehyde,2-hexenal,heptaldehyde,nonanal,(E,E)-2,4-heptadienal,and caryophyllene oxide in high content and there were significant differences.3)Using modern instruments combine with human senses to detect samples,which can be obtained by electronic nose(E-Nose)analysis,the samples were divided into four categories,consistent with the classification results of discriminant function analysis(DFA).The result was same with GC-TOF-MS results of the raw data.Taking the data of the eighteen sensors of the electronic nose as the independent variable,the relative content of the four major types of compounds detected by GC-TOF-MS was used as the dependent variable to establish the PLS model.The regression equation R~2>90%,and the PLS model between the actual value and the predicted value was good,indicating that the electronic nose had a good correlation with the data detected by GC-TOF-MS.The LY/AA and P40/1 sensors had a great influence on the alcohols,aldehydes,ketones and esters in the volatile substances detected by GC-TOF-MS.Different proportions of Pterocarya stenoptera C.DC tea were analyzed by electronic nose,and the results were good for distinguishing adulterated samples.The human nose was combined with gas chromatography-sniffing method(GC-O)to detect 15 kinds of main volatile substances.It was found that a substance having a high FD value or an odor activity value(OAV)such as myrcene,phytol,and geranyl acetate played a main role in odor contribution.The determination of the main chemical components found that the content of polysaccharides,flavonoids,triterpenoids and scutellarin I was different in different samples.The evaluation of different samples by the product testers were also different.The sample of Pterocarya stenoptera C.DC tea was analyzed by electronic tongue(E-Tough),and the results were well differentiated.The fingerprint of Cyclocarya paliurus tea volatile substances and the analysis of modern instruments can be used comprehensively and effectively from tea flavors for the basic research and quality control of flavor substances.