【作者】 李祥龙；

【导师】 许靖逸； 刘本英；

【作者基本信息】 四川农业大学 ， 农业硕士（专业学位）， 2019， 硕士

【摘要】 雅安藏茶是最早的黑茶,也是最典型的黑茶。其制作工艺已列入我国非物质文化遗产。经特殊工艺持久发酵制作而成的雅安藏茶含有多种对人体有益的物质,并具有独特的风味和保健功效。雅安藏茶渥堆和后发酵过程中均存在大量的微生物,微生物对藏茶品质的形成起了重要的作用。目前,对雅安藏茶中存在的微生物的研究主要集中在渥堆阶段,而对成品雅安藏茶中存在的微生物的研究却很少。长期的陈放过程中微生物的种类如何,数量多少,是否存在致病性微生物,至今尚未有研究报道。本试验采用四川雅安藏茶主产区7个厂家生产的14个代表性雅安藏茶(散茶和压制茶)为材料,通过涂布法和平板计数分离法,利用形态学、生理生化实验结合分子生物学方法对其进行分离和鉴定,探索成品雅安藏茶中微生物的数量、种类、优势微生物类群及致病菌存在状况;用不同(沸水、煮沸)处理茶样,对比不同处理的茶汤中微生物数量和种类的差异,以为雅安藏茶的安全饮用提供科学的理论依据。试验结果如下:(1)成品雅安藏茶中分离到的微生物主要是细菌,数量为10~4CFU/g,个别散茶中数量达到10~5CFU/g;霉菌数量次之,为10~2CFU/g,个别散茶中数量达到10~3CFU/g;酵母菌仅在散茶中才能检测到。(2)在所有雅安藏茶样品中,共分离出14株霉菌,选取5株优势霉菌进行形态学和分子生物学鉴定,结果为黑曲霉(Aspergillus niger)、烟曲霉(Aspergillus fumigatus)、杂色曲霉(Aspergillus versicolor)、橘青霉(Penicillium citrinum)、根霉属(Rhizopus sp.);此外,还分离出4种优势细菌,鉴定结果为枯草芽孢杆菌(Bacillus subtilis)、土壤短芽孢杆菌(Brevibacillus agri)、类短短芽孢杆菌(Brevibacillus parabrevis)、类芽孢杆菌属(Paenibacillus sp.);并鉴定出1株酵母菌为Jaminaea属(Jaminaea sp.)。(3)在致病性细菌的检测中,均未检测到致病菌大肠杆菌、金黄色葡萄球菌、沙门氏菌和志贺氏菌。(4)经沸水和煮沸处理的茶汤中微生物的数量和种类明显减少,检测不到霉菌和酵母菌,且分离出的微生物数量均低于茶饮料中国标规定的微生物限量标准。综上所述,成品雅安藏茶中存在的微生物对饮用藏茶无安全隐患,本研究结果将对消费者放心饮用雅安藏茶提供理论依据。更多还原

【Abstract】 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.更多还原