Study On Volatiles And Scent Of Green Tea

Green tea is popular in daily consumption with the largest production and sale among six major teas. The aroma of green tea is generally grouped into refreshing fragrance, floral fragrance and baked stir-fry fragrance. The research on green tea aroma mainly focused on the influence of varieties, cultivation, processing, storage and other conditions. However, it is still need to be further studied on the quantitative analysis and contribution of volatile compounds to green tea aroma. The present study analyzed the volatile composition of a large number of green tea in difference varieties and picking time on the basis of the optimal extraction conditions of HS-SPME method. At last, the green tea scent was classified using a multinomial Bayes classifier with the data combined with sensory evaluation.1. Effects of difference extraction temperature on green tea volatiles were studied. The results showed that 40℃ was the best extraction temperature for getting most volatile compounds with the best GC-MS separation efficiency.2. The standard curves of 15 kinds of common volatiles of green tea has been established, including hexanal, leaf alcohol, tea, benzaldehyde, linalool,4-terpineol, a-terpineol, citral, nerol, geraniol, benzyl alcohol, phenylethyl alcohol,β-ionone, nerolidol and indole. And the good linear regression equation of each component showed a positive correlation between concentration and relative content.3. In 94 samples of green tea, a total of 125 kinds of volatiles were detected, of which alcohols content was the most. And,10 compounds with highest relative contents were linalool, geraniol, dimethyl sulfide, linalool oxide Ⅱ, cis jasmine, 2,4-bis(1,1-dimethylethyl)-phenol, methyl salicylate, hexanal, linalool oxide I and 4-methyl-3-penten-2-one.4. The types and contents of green tea volatiles were influenced by the processing and picking season. Basking in 30 minutes has the highest volatile contents. The relative contents of volatiles from fixing samples were significantly higher than that of steaming samples. Compared to summer tea, the types of volatiles and the average relative contents of spring tea samples were significantly higher, excepting few materials such as dimethyl sulfide,3-methyl-butanal,2-ethyl-1-hexanol and 1,7,7-trimethyl-bicyclo[2.2.1]hept-2-ene.5. Aroma types of green tea can be divided into chestnut-like scent, green tea flowers scent and oolong tea flower scent using the volatiles data combined with sensory evaluation. The result is consistent with that of multinomial Bayes classification. Multinomial Bayes classification can be applied to distinguish the green tea scent.