绿茶主要多酚类涩感物呈味效应与互作机制研究

Green tea is one of the most important teas in China. "Astrigent taste", which significantly influence the flavor quality of green tea, is the immediate cause which leads to low quality and low availability of summer and autumn tea. Polyphenols are the main chemicals for astringent taste. The chemical constituents of polyphenols are relatively clear, but the key astringent chemicals and their taste interactions have been not explicit. Without systemic interaction-mechanism study, it is impossible to achieve the objective evaluation and accurate control. This project uses LC-MS to analyse main taste compounds contents, and use quantitative sensory analysis method and TDA technology to analyse the taste attributes of main astringent polyphenols. It will clear the key astringent polyphenols by using polyphenols-protein astringency model, taste construction and reduction technology. Then we will study the taste interactions between astringent chemicls, and between polyphenols and not astringency factors (other taste chemicals and environmental effect factor). At last, we will analyse and reveal the interaction mechanism for the astringent taste of green tea infusion. The results will clear the key astringent polyphenols and taste effect, and improve the taste theory of green tea infusion. The results also provide theory base for tea infusion taste regulation, and help to improve the quality of low-and-medium-grade green tea and its efficient utilization.

绿茶在我国茶产业中占据着重要地位。“涩感”是影响绿茶品质极为重要的负面感官性质和主要评判指标，是导致我国占比高达60%以上的夏秋绿茶品质及其利用度低下的重要原因。多酚类是绿茶主要涩感化合物，其化学组成已较为清晰，但关键涩感物及其呈味互作效应并不明确，缺乏系统的作用机制，无法实现有效调控，制约了夏秋茶资源的进一步利用。本项目采用LC-MS等技术分析典型绿茶多酚组分含量，整合量化描述感官分析技术与滋味稀释分析（TDA）技术研究主要多酚涩感物呈味特性及涩感贡献率；创建多酚-蛋白涩感评价模型，结合滋味重构与消减技术明确关键多酚涩感物；重点开展绿茶关键多酚涩感物间呈味效应及其与非涩感影响因子间的互作效应，揭示其作用机制，探索绿茶茶汤涩感调控方法。研究结果不仅可以探明绿茶茶汤关键多酚类涩感物及其呈味效应与作用机制，完善绿茶滋味化学理论，而且对改善中低档茶滋味品质及其资源高效利用都具有重要意义。

项目重点研究了儿茶素、酚酸及黄酮糖苷等涩感特性、儿茶素之间及与酚酸的呈味互作效应、涩感物与其他滋味物质间的呈味互作效应，深入探讨其呈味互作机制，并初步提出可改善夏秋茶涩味的加工技术。研究结果对完善绿茶滋味理论体系和改进茶制品加工技术都具有一定的意义。项目在以下6个方面取得进展。（1）研究明确了酯型儿茶素EGCG、ECG及芦丁等黄酮苷为绿茶茶汤的关键涩感物；（2）研究明确了儿茶素涩感之间呈叠加效应，而儿茶素EGCG与酚酸涩感之间呈协同效应；（3）初步揭示了钙离子等促进酚类物质与唾液蛋白络合增强涩感的作用机制；（4）初步提出采用生物酶催化等方式可有效调控夏秋茶涩感强度；（5）发表学术论文14篇，其中SCI论文8篇；（6）获得授权发明专利3项，培养青年技术骨干2名，培养硕士生2名。现已完成了计划研究内容，实现了项目预期目标。