| Pu-erh tea is one of the representative dark tea in china.For its unique flavor and health care functions, more and more consumers at home and abroad like drinking it in recent years. The"stale flavor"of pu-erh tea is the one of the main quality characteristics as well as the decided factors of the price in the market. However, due to lacking of advanced analytical equipments and evaluation methods, the characteristic aroma components of Pu-erh tea has not been identified up to now. In this study, Heads space solid phase microextraction( HS-SPME) was optimize, The aroma components of Pu-erh tea and their variation in the process were studied by using HS-SPME/GC-MS, and the characteristic aroma components were further identified by GC-MS /GC-Olfactometry.The main research results are as follows:1. HS-SPME method was choosen to extract the aroma components of pu-erh tea.the analytical condition that influence the effect of the aroma extraction, such as the selection of extration fiber, the extraction time, the extraction temperature in water-bath, the brewing proportion of tea and water etc were optimized. The best extracted conditions were selected as following: the fiber is 65μm SPME head (DVB/ PDMS), the extraction time is 60 min, the extraction temperature in water-bath is 60℃and the brewing proportion of tea and water is 1:3.2. Five tea samples were selected from Pu-erh Tea, Green Tea, Black Tea, Oolong Tea and White tea .The aroma constituents of these samples were determined by HS-SPME/GC-MS. The aroma formation in pu-erh tea and other teas were shown to be of great difference. The biggest difference in aroma constituents between Pu-erh tea with other tea samples is that pu-erh tea were identified with higher contents of heterocyclic oxygen compounds( 20.84%) .3. The change of aroma constituents in Pu-erh raw tea during the pile-fermentation process were determined by HS-SPME/GC-MS. Results showed that the alcohols and hydrocarbons decreased distinctively but the heterocyclic oxygen compounds increased distinctively during the pile-fermentation process; 1,2,3-trimethoxybenzene was the most abundant component in the heterocyclic oxygen compounds and its content reached the highest when the pile-fermentation process finished.4. Five Pu-erh tea samples with stale flavor were selected from 36 samples by sensory tests, and the aroma constituents of these samples were determined by HS-SPME/GC-MS. Furthermore the mainly difference in aroma constituents between Pu-erh tea with stale flavor and other Pu-erh tea samples was discussed in this study. Results showed that the aroma constituents of Pu-erh tea with stale flavor were mainly heterocyclic oxygen compounds and alcohols, The contents of 1,2,3-Trimethoxybenzene in Pu-erh tea with stale flavor were 9.0%,lower than that 12.3% in other pu-erh tea, but the total content of heterocyclic oxygen compounds in Pu-erh tea with stale flavor was the same as other Pu-erh tea samples.The content of Alcohols and Hydrocarbons were lower but the Aldehydes and Ketones were higher in Pu-erh tea with stale flavor than other Pu-erh tea samples ,.there were many difference inβ-Linalool,β-Terpineol,β-ionone, Decanal, Nonanal,β-cyclocitral, Methyl Salicylate, Longifolene.etc between Pu-erh tea with stale flavor and other pu-erh samples.5. Volatile components of pu-erh tea were extracted using HS-SPME and the major flavor compounds were identified by GC-MS/GC-Olfactometry. Results showed thatβ-Terpineol,andβ-Linalool oxides,1,2,3-Trimethoxybenzene, 4-ethyl-1,2-dimethoxy-benzene, 1,2-dimethoxy-, 1,2,3-trimethoxy-5-methyl-benzene,1,2,4-Trimethoxybenzene,β-ionone, Decanal,Dihydro actinidiolide, Geranyl acetone,α- Cedrene,etc have great contribution to the flavor of pu-erh tea. A m o n g t h e m , 1 , 2 , 3 - T r i m e t h o x y b e n z e n e , 4 - e t h y l - 1 , 2 - d i m e t h o x y - b e n z e n e , , 1,2-dimethoxy- benzene,, 1,2,3-trimethoxy-5-methyl- benzene,,1,2,4-Trimethoxybenzene,etc were the characteristics aroma components of pu-erh tea with"stale flavor".
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