制曲原料中添加绿茶对大曲发酵过程理化特征及细菌多样性的影响

Effect of Adding Green Tea on Physicochemical Characteristics and Bacterial Diversity of Daqu during Fermentation

基于高通量测序技术和数理统计手段,以小麦曲(原曲)为对照,探究按10%、20%和30%比例加入绿茶制曲,对大曲发酵过程理化特征、细菌群落多样性和演替方面的作用和影响。结果显示,添加绿茶可有效提升大曲群落多样性,并提高大曲糖化力、水分含量和酸度,但茶叶添加比例与群落多样性的升高不呈比例关系,各类曲中特有的群落系统进化结构是影响大曲理化特征的主要因素。发酵过程中,4类曲在中挺期开始出现演替分化,并至发酵结束形成各自独特的群落结构。变形杆菌门、厚壁菌门、拟杆菌门和放线菌门对4类曲群落演替存在不同程度影响,进而驱动各类曲出现不同的理化特征,其中Pseudomonas(假单胞菌属)是原曲和10%添茶曲的重要贡献菌群,乳酸菌Weissella(魏斯氏菌)和Pediococcus(片球菌)是20%添茶曲的重要贡献菌群,Bacillus(芽孢杆菌)是30%添茶曲的重要贡献菌群。本研究结果可为添茶曲的工艺优化和多原料制曲提供理论基础,对于大曲制备工艺和茶叶应用具有一定的指导意义。

In this study,high-throughput sequencing technology and statistical analysis were employed to explore the effects of adding green tea at proportions of 10%,20%,and 30%on physicochemical characteristics,bacterial community diversity and succession of Daqu during fermentation compared with pure wheat Daqu(control).The results showed that the addition of green tea significantly increased the bacterial community diversity of Daqu and improved its saccharification capacity,moisture content and acidity.However,the increase in tea addition did not exhibit a proportional relationship with the community diversity.The unique evolutionary structure of the bacterial communities in different types of Daqu was found to be the major factor affecting the physicochemical characteristics of Daqu.During the fermentation process,all four Daqu exhibited differentiation in bacterial community succession starting from the thermophilic stage,thereby leading to the formation of their unique community structure at the end of the fermentation process.The phyla Proteobacteria,Firmicutes,Bacteroidota,and Actinobacteria showed varying influences on the community succession of the four Daqu samples,thus making each of them have different physicochemical characteristics.Specifically,Pseudomonas was an important bacterial genus contributing to the physicochemical characteristics of the control and 10%tea Daqu,while Weissella and Pediococcus,were important contributors to the physicochemical characteristics of the 20%tea Daqu.Bacillus was found to be a significant bacterial genus contributing to the physicochemical characteristics of the 30%tea Daqu.This study provides a theoretical basis for process optimization in the production of tea-added Daqu and for the development of multi-raw material fermentation starters.It also has implications for improving the preparation process of Daqu and the application of tea in Daqu making.