Changes Of The Composition In Fermentation Process Of Pu-er Tea And Preparation Of Caffeine

In this paper,the analytical method of and determination method of active ingredients in Pu-er tea was established.And the microorganisms in fermented tea was isolated and identified,and new fermentation process of Pu-er tea was studied.The microflora in traditional natural fermented Pu'er tea and machine fermented Pu'er tea were separated and identified:the ratio of dominant strains of bacterias in the traditional fermented tea Aspergillus japonicus:Aspergillus niger:uncertain species was 9:11:3.In the machine fermented tea Aspergillus japonicus:Aspergillus niger:uncertain species was3:7:1.In accordance with the above two percentage,inoculating seeds were prepared and were compared with the non-inoculated test.The results showed:the quantitative relationship of the dominant strain in the 2 batches was:Aspergillus niger>Aspergillus japonicus>uncertain species,Aspergillus niger and Aspergillus japonicus were the main species.The fermentation of artificial inoculation start quickly,tea color transfected fastly.Compared with the traditional tea fermentation time(typically 40 to 60 days),The fermentation period was 16d?20d in this study,The optimum fermentation temperature was 45 ?-55 ?..The effective components in Pu-er tea were determined by HPLC.the fermented tea in this study contained caffeine and gallic acid mostly.Other active ingredient content of catechins were little or almost absence.Extract caffeine from mechanical Pu-er tea(500g)With Ethanol.availability of crude extracts was 44.97g,the extraction rate was 9.0%.And then the crude product was dissolved in water,extracted with dichloromethane,the organic layer containing the crude caffeine was 14.49g,the yield was 2.9%;aqueous layer containing the crude product gallic acid and catechin 30.48g,the yield was 6.1%.Taken crystallization and ion exchange resin method to purify Caffeine,the result display:the pale yellow caffeine(0.43g)was obtained by the crystallization method from crude product(0.5g),the yield was 82%,relative to the mechanical Pu'er raw materials(500g),the yield was 2.4%;the white caffeine(4.54 g)was obtained by the ion exchange resin method from crude product(6g).the yield was 75.67%,relative to the mechanical Pu'er raw materials(500g),the yield was 2.19%.Isolation and screening of microorganisms from the naturally fermented Pu-er tea,to determine the dominant strain,artificial inoculation fermentation by the proportion of the dominant strain,application of this method can effectively control the types of bacteria,the bacteria is not easy to grow,the time is reduced to 16-20d.That overcomed the defects such as the long fermentation cycle in traditional fermentation,unstable product quality,too much bacteria,and large blindness,etc.