牛肝菌是一类味道鲜美的野生食用菌，不同种类的牛肝菌呈现不同程度和方式的鲜味。经加工后，牛肝菌的鲜味有显著的变化。前期的研究主要集中在呈味氨基酸以及核苷酸等已知的有效成份，但是这些已知成份不足以解释牛肝菌鲜味的多样性。很显然，牛肝菌中存在未知的其它鲜味成份，其加工过程中呈味物质的变化规律也有待澄清。初步研究结果显示，牛肝菌中的鲜味肽可能是其呈现不同鲜味和加工过程中呈鲜的主要鲜味活性分子。本项目拟选取五种牛肝菌为切入点，利用现代分离分析技术，结合感官分析, 鲜味受体T1R1/T1R3筛选技术，对新鲜、热加工及酶处理的牛肝菌进行研究，分析比较不同处理牛肝菌中呈味肽的结构、呈味特性及变化趋势，研究鲜味肽呈鲜的规律，再进一步通过人鼠受体嵌合模型，定点突变等技术，从分子水平上论证鲜味肽调节鲜味受体的作用方式，阐明牛肝菌鲜味肽的分子机制，并为牛肝菌的加工储藏和牛肝菌风味调料的开发提供理论基础和技术支持。

Bolete is a class of wild edible mushrooms. Differrent species of bolete present a variety of savory taste profiles, which change dramatically after processing. Previous studies focused primarily on known umami molecules, such as amino acids and ribonucleotides. However, it is obvious that additional and unknown umami ingredients exist in bolete, as the variety of savory profile seen in bolete cannot be fully explained by the known umami molecules. It is also not clear how these umami molecules change during processing. Our preliminary results point to umami peptides as the major contributors to the savory profile of bolete.With this research proposal, we plan to select five boletes as the starting point, and use modern isolation/purification technology and umami receptor assay to identify the unknown savory peptides. Following identification of the active ingredients, we will perform structural analysis and characterize the impact of processing on these ingredients. Furthermore, we will use sensory test in combination with humam-rat chimeras and mutagenesis study to illucidate the molecular mechanism of these molecules. In summary, this research proposal could potentially lead to identification of novel savory ingredients, a deeper understanding of the molecular mechanism of umami taste, as well as application guidance over bolete processing and storage.