Study On The Aroma Components Of Yunnan Black Tea By Using GC-MS And Electronic Nose

In this study,gas chromatography-mass spectrometry(GC-MS)and electronic nose were used to study the aroma components of Yunnan black tea.The main contents were as follows:1 A comparative study of different polarity chromatographic columns in analysis of aroma components in Yunnan black teaThe saparation effects of two different polarity chromatography columns was compared.The separation effects of non-polar chromatographic column HP-5MS and standard polar chromatographic column CP-Wax were good,and there were some differences between the analysis results.Chromatographic column HP-5MS was more suitable for the aroma of Yunnan black tea.2 Study on the application of electronic nose combined with GC-MS in the analysis of aroma compounds of Yunnan black teaA pretreatment and analysis method were proposed in this study.46 different Yunnan balck tea samples were divided into A,B and C three classes by using electronic nose.Futhermore,in order to select suitable fiber the sensitivity of five fibers with different polarities were examined.As a result,75 ?m CAR/PDMS showed good extraction efficiency for the aroma compounds of Yunnan black tea.10 representative black tea samples were futher analysed by using GC-MS.The results showed that the aroma compounds which led to the differences in the three classes of Yunnan balck tea were mainly include linalool,linalool oxide,geraniol and methyl salicylate.Futhermore,it also included some other main aroma compounds of Yunnan black tea,such as dihydrolinalool,a-terpineol,nerolido,benzaldehyde,?-ionone and some other compounds with low content.3 Quantitative analysis of the main aroma compounds of Yunnan black teaTaken the peak area as index,the sensitivity of five fibers with different polarities were examined.As a result,50/30?m DVB/CAR/PDMS,65?m PDMS/DVB and 75 ?m CAR/PDMS showed good extraction efficiency for the main aroma components of Yunnan black tea.The extraction conditions such as the ratio of tea to water,extraction temperature,extraction time and the rate of agitation to extraction efficiency were investigated.The optimal HS-SPME conditions of 50/3?m DVB/CAR/PDMS,.65?m PDMS/DVB and 75?m CAR/PDMS were developed.Under the optimal conditions,the proposed method affords a wide of linearity for the main aroma compounds,good linear regression coefficients(R2?0.995),and the limits of detection were below 20 ng/g.The method accuracy and repeatability is satisfactory.