Isolation And Identification Of Main Microorganisms In Finished Ya'an Tibetan Tea

Ya'an Tibetan Tea is the earliest dark tea and the most typical dark tea.Its production process has been listed as China's intangible cultural heritage.Ya'an Tibetan Tea,which has been produced by special process and long-lasting fermentation,contains a variety of substances beneficial to the human body,with unique flavor and health benefits.Microorganisms have played an important role in the formation of quality characteristics of Ya'an Tibetan tea.At present,the research on the microorganisms existing in Ya'an Tibetan tea is mainly concentrated in the pile-fermentation stage,but there are few studies on the microorganisms present in the tea of Ya'an Tibetan tea.What kind of microorganisms exist in the long-term precipitation process,the quantity and whether it exists pathogenic microorganisms have not been reported so far.In this experiment,14 representative Ya'an Tibetan tea(loose tea and pressed tea)produced by 7 factories in Ya'an Tibetan tea producing area of Sichuan Province were used as materials.The microorganisms in Ya'an Tibetan tea were separated and identified by coating method and plate counting separation method.The quantity,species,dominant microorganisms and pathogenic bacteria in Ya'an Tibetan tea were explored by morphological,physiological and biochemical experiments combined with molecular biological methods.In order to provide a scientific theoretical basis for safe drinking of Ya'an Tibetan Tea,the difference of microorganism quantity and species in tea soup treated with different methods(boiling water and boiling)was compared.The results are as follows:(1)The microorganisms isolated from the finished Ya'an Tibetan tea are mainly bacteria,the number is 104 CFU/g,the amount of individual loose tea reaches 105 CFU/g.The second is the number of molds,the number is 102 CFU/g,and the amount of individual loose tea reaches 103 CFU/ g.Yeast can only be detected in loose tea.(2)In all Ya'an Tibetan tea samples,14 strains of mold were isolated,and 5 dominant molds were selected for morphological and molecular biological identification.The results were Aspergillus niger,Aspergillus fumigatus,Aspergillus Versicolor,Penicillium citrinum and Rhizopus sp.;in addition,four dominant bacteria were isolated,and the results were identified as Bacillus subtilis,Brevibacillus agri,Brevibacillus parabrevis,Paenibacillus sp.;and one strain of yeast was identified as Jaminaea sp.(3)In the detection of pathogenic bacteria,no pathogenic bacteria such as Escherichia coli,Staphylococcus aureus,Salmonella and Shigella were detected.(4)The quantity and species of microorganisms in Ya'an Tibetan tea tea soup after boiling water and boiling treatment were significantly reduced,mold and yeast were almost undetectable,and the number of microorganisms was lower than the microbial limit standard specified for tea beverages.In summary,the microbes present in the finished Ya'an Tibetan tea have no safety hazards for drinking Tibetan tea.The results of this study will provide a theoretical basis for consumers to safely drink Ya'an Tibetan tea.