Study On The Effects Of Pan-firing And Baking Temperature On The Aroma Type And Characteristic Of Green Tea

A key aspect of tea quality is the aroma.More recently,there has been extensive research on active compounds of famous green tea.However,the research of the constitution of green tea is limited by the material.Previous research on green tea aroma has found that manufactory progress is one of the most important factors affecting tea aroma.Besides,pan-firing and baking are two of the most vital stages of manufactory progress.Therefore,in this paper,green tea samples were pan-fired at 220,270 and 320 ? respectively.Each of them was employed for the roasting stage under different temperatures of 80,100,120 and 140 ? respectively.Each set of them sampled every 60,45,30 and 30 min respectively.After that total 67 samples were prepared for further analysis.Quantitative descriptive analysis(QDA)and cluster analysis(CA)were used to classify the processed green tea according to its aroma type.Gas chromatography-mass spectrometry(GC-MS),gas chromatography-olfactometry(GC-O)and external standard quantitative method were used to analyse the volatile compounds in green tea with different aroma types to clarify the composition of volatiles of them.The main research contents and achievements are as follows:1.To evaluate the aroma attribute of green tea,an evaluation system for it were established by QDA.After that,cluster analysis(CA)was employed to analyze the statistics which got by QDA.According to the CA results,the 63 baking samples were divided into five categories: tender flavor,bean flavor,baking flavor,chestnut flavor and integrated flavor.Also,the samples with grass flavor prepare to pan-firing temperature of 270 ?,while the tender,baked,chestnut,etc samples were inclined to pan-firing temperature 320 ? and 370 ?.2.Volatile compounds of tea samples were extracted by headspace-solid phase micro extraction(HS-SPME)and detected by GC-MS.A total of 128 volatile compounds were identified from 67 samples,and 17 common compounds were found in the samples,among which linalool and its oxides,geraniol,?-terpenol and phenylacetaldehyde were the most abundant.All other factors being equal,with the rise of baking temperature,the types of volatile compounds increased gradually,and the increased compounds were mainly pyrroles and pyrazines.3.The active aroma compounds of 5 typical green tea samples were identified by GC-O combined with OAV.The results showed that the active aroma compounds of integrated green tea were mainly 2-methylbutyraldehyde,isopentyl alcohol and benzaldehyde;the active aroma compounds of baked green tea were mainly dimethyl sulfide,2-methylbutyraldehyde,pyrrole,2,5-dimethyl pyrazine,etc.;the active aroma compounds of chestnut green tea are mainly dimethyl sulfur,cis-3-hexenol,1-heptanol,1-octen-3-ol,etc.;the active aroma compounds of bean green tea were mainly 2-methylbutyraldehyde,cis-jasmon,1-octen-3-ol,?-ionone,etc.and the active aroma compounds of green tea were mainly hexanal,?-myrcene,isovaleraldehyde and so on.