茶叶后发酵机制与质量安全预测性控制机理研究

Post-fermented teas occupy an important position in Chinese tea industry, such as Puer tea, Liubao tea, Fu tea etc. post-fermentation is the key process to formed their unique flavor and functional quality, which also determined to the hygiene and safety for Post-fermented teas. While, there are series food safety riskes existing in post-fermentation process. on the basis of a series earlier research of quality formation mechanism and toxicology of Pu-erh tea, this project is plan research correlation between quality on security as well functional and fermentation mechanism of post fermented process, evaluate security risk of dominant microbes and their metabolites, interaction between dominant microbes, Unlimited time and space aging and storage process as well to post fermented tea using comprehensive analysis method such as hazard factors analysis，fermentation metabolic analysis combined with harmful organisms evaluate, toxin chemical and toxicology safety evaluation with the Puer tea for mode. this project will helpful specific beneficial microbe, control harmful organisms, guide and provide scientific support transition from traditional Post-fermented tea processes of which fermented by Natural mixed microorganism fermentation to advanced fermentation process which through People industrial control microorganism and subsection control microorganism fermentation mechanism; Promote transition of fermented tea quality control through limited Finished products quality examination to through effective predictive safety quality process control, which will helpful improve hygiene quality of post fermented tea effectively and promote post fermented tea quality standards reached the International CAC standards level, breakthrough export technical barriers.

普洱茶、茯砖茶、六堡茶等后发酵茶在我国茶业中占有重要地位，后发酵加工是形成特殊功能风味的基础，更是决定其卫生安全品质的关键环节；工艺全凭经验，操作千差万别是后发酵茶加工的现状，大量不明自然接种的霉菌、酵母菌、细菌参与，不限时空条件的收藏，传统后发酵机制存在重大安全风险！现有相关安全研究局限于对终端产品有限检测，缺乏预测性安全控制机制。在对后发酵茶品质形成机理及毒理学前期研究基础上，采用有害微生物分析、毒素化学分析和毒理学评价结合的综合分析法，对"仓贮微生物后发酵"等三种后发酵机制的安全性进行研究：重点探明参与微生物及其代谢产物的安全性，明确后发酵条件及微生物间互作对微生物毒素代谢的影响调控机理。以促进自然接种杂菌发酵到控菌发酵的工艺革新，安全科学利用微生物；为"茶叶多菌复合分段控菌发酵机制"设想提供依据；对保护消费者健康，突破出口绿色壁垒，实现茶叶后发酵加工安全预测性全程控制具有重要意义。

四年来，项目组根据基金委项目计划任务书要求，围绕普洱茶发酵优势微生物茶叶发酵代谢功能为主要内容，展开对普洱茶发酵机制与质量安全预测性控制研究，主要研究内容和结果如下： .（1）项目通过对系列自然渥堆普洱茶发酵优势菌的菌种分离纯化、形态学和分子鉴定，茶叶发酵生化转化功能及氧化酶产酶能力评价，微生物毒素分析、挥发性组分及安全性研究，初步建立起了一个普洱茶发酵微生物综合研究体系和菌种数据库，为下一步普洱茶现代化人工接种控菌发酵打下了一定的物质和理论基础；.（2）项目研究获得测试普洱茶中系列真菌毒素的检测方法，通过对部分普洱茶发酵优势真菌茶叶单菌发酵样品的筛查分析，找出了一些茶叶发酵产毒菌株和非产毒素菌株，初步从定性和定量角度评估了这些菌株作为普洱茶发酵菌种的安全风险，可以直接或间接为普洱茶发酵安全卫生品质预测性控制提供科学依据；.（3）项目通过生化分析定性分析了一些微生物发酵代谢挥发性组分可能存在的风险，尝试利用果蝇和酵母作为毒理学研究模式生物分析了普洱茶发酵微生物在实验室茶叶纯菌发酵体系中代谢的挥发性成分的安全性，证明在茶叶发酵条件下这些种菌株代谢挥发性成分的安全性较高，对模式生物果蝇的发育和生命周期没有显著影响，对酵母菌生长没有显著影响。 .（4）项目研究发现那些产酶能力强的菌株处理的茶样色泽变化最显著，进一步明确了微生物分泌的多酚氧化酶在普洱茶发酵变色和多酚类氧化作用起着主导作用。.（5）项目研究了普洱茶发酵过程中一些他汀类物质的产生菌的代谢调控和安全风险问题，对更好发展利用普洱茶降脂保健功能有重要意义。