青砖茶烯醛类物质的呈香特性及形成机制

Huibei Qingzhuan tea is one of the most important border-selling tea in China, which has unique stale flavor characteristics. However, owing to the poor studies on the key aroma compounds in high quality Qingzhuan tea satisfied by Chinese tea customers, the development of the Qingzhuan tea and industrial level is seriously affected. Our previous study showed the olefine aldehydes are key aroma components of Qingzhuan tea, but the aroma characteristics and formation mechanism of olefine aldehydes are still unclear. Based on the existing studies, recombination of aroma models and addition/omission tests are carried out. Therefore, we are ready to use sensomics to analyze the aroma characteristics of olefine aldehydes in Qingzhuan tea, and use metabonomics and lipidomics to study the dynamic evolution of key olefine aldehydes in the pile-fermentation process, then the metabolic flow of target precursors are tracked by using the stable isotope labeling technology. Finally, the formation mechanism of olefine aldehydes is analyzed based on the integration of multi-omics data. The implementation of the project would not only illuminate the critical fundamental theory of aroma quality formation in the production process of Qingzhuan tea, but also provide technical support for directional improvement of production technology and precise regulation of high quality flavor types of Qingzhuan tea products.

湖北青砖茶是我国三大边销砖茶之一，具有独特的“陈香”风味。由于目前我国消费者认可的高品质青砖茶感官质量评价标准及其特征风味组分相关研究缺失，严重影响了青砖茶品质和产业水平的提升。本申请拟在前期发现烯醛类物质是青砖茶关键香气成分的基础上，继续研究其呈香特性及在渥堆发酵过程中的形成机制。开展实施香气模型重组和消增技术，系统运用感官组学分析烯醛类物质的呈香特性；采用代谢组学和脂质组学分析关键烯醛类香气成分在渥堆过程的动态衍变，进而结合稳定性同位素标记技术示踪目标前体物质的代谢流，基于多组学数据整合解析烯醛类物质的形成机制。本项目实施不仅能够阐明青砖茶生产过程中香气品质形成的关键基础理论，而且为定向改进生产工艺、实现青砖茶产品优质香型的精准调控提供技术支撑。

青砖茶具有独特的香气特征和保健功能，备受国内外消费者的关注，其中“陈香”是青砖茶的一种典型香型。青砖茶常因渥堆发酵条件难控制而导致其产品的风味不稳定，至今尚不明确其香气特征成分组成、呈香特性及形成机制。本项目主要通过感官组学、脂质组学及代谢组学等多组学数据的系统整合和深度挖掘，解析青砖茶中关键烯醛类香味化合物的呈香特性及形成机制。主要研究结果有：（1）首先对青砖茶香气成分进行定性、定量分析，采用气相色谱嗅闻法（GC-O）和气味活度值（OAV）鉴定特征香气成分主要为烯醛类和酮类，通过单个单体风味描述、两个及三个单体互作分析，明确了关键香气成分的呈香特性及互作机制；（2）香气重组试验证明关键香气成分的组合可以较好的重现青砖茶风味，缺省试验证明了烯醛类物质、酮类物质，尤其是反,反-2,4-癸二烯醛、β-紫罗酮对青砖茶风味的重要性；（3）通过脂质组学明确了青砖茶加工中游离脂肪酸及氧化脂肪酸的衍变规律，从渥堆陈化到成品茶，脂肪酸的转化是以降解为主，加工过程以α-亚麻酸和顺式-9,12,-亚油酸变化极显著、转化率最大，而氧化脂质总量在加工期间总体呈增加趋势，尤其是亚麻酸类、亚油酸类脂质显著增加；（4）关键差异脂质成分与香气成分的相关性分析及代谢通路分析表明，与关键香气成分呈现正相关的主要为不饱和烯醛类和酮类成分，涉及代谢通路主要有不饱和脂肪合成等途径；（5）通过同位素示踪亚麻酸在渥堆发酵期间的代谢流，证实了亚麻酸产生多种氧化脂肪酸，进而形成醛类等成分;目标脂质前体的模拟试验结果表明，部分醛类和酮类成分都可以α-亚麻酸和亚油酸脂质作为前体物质通过酶促或非酶促降解反应生成。本研究结果不仅有助于深入理解烯醛类香气物质的形成机制，且为实现青砖茶产品优质香型的精准调控奠定基础。