The Microbiome Of Raw Material Influences The Flavor Compounds Of Jiang-Flavor Baijiu

High-temperature Daqu plays a vital role in the brewing of Jiang-flavor Baijiu.It was made from raw materials and fermented at high-temperature to form a special Daqu microbial community with unique process.The quality of high-temperature Daqu is closely related to the quality and flavor of Baijiu.The raw materials are an important source of Daqu microorganisms,of which wheat raw materials are the most important.These microorganisms in different environments then bring more possibilities for the evolution of the microbial community in Daqu,thereby affecting the metabolism of flavor microorganisms and affecting the quality and flavor of Baijiu.However,there are few related studies at present,it is difficult to effectively guide the selection of raw materials for Daqu making from different producing areas.In this study,we collected 21 wheat samples,8 water samples and 5 rice straw samples from different producing areas,and focused on the microbial composition of the raw materials and the volatile compounds of Daqu.Through 16 s DNA full-length sequencing and internal transcribed spacer(ITS)region sequencing,we revealed the microbial composition of the raw materials.Based on the high-temperature Daqu production process,Daqu was prepared by simulated solid-state fermentation.Using HS-SPME-GC-MS,the flavor compounds of simulated Daqu were analyzed and evaluated.This study assists with understanding the effects of the microbiome on the flavor compounds of Daqu.More importantly,this study lays a foundation for guiding the selection of raw materials for Daqu making and exploring the relationship between the microbial composition of raw materials and the flavor of Daqu.The main results of this study were as follows:(1)Based on high-throughput sequencing technology,the microbial community composition of 21 wheat samples were analyzed.A total of 23572 OTUs were obtained by 16 S rDNA sequencing.In the wheat samples from Guizhou Province,Pantoea was the dominant bacteria,which accounts for 31.98%;the main fungus was Epicoccum,which accounts for36.83%.Compared with the microbial composition of the local wheat in Guizhou Province,the main sauce-flavored production area,the wheat samples in Anhui Province was the closest to those in Guizhou Province,and the samples from Hubei Province had the largest difference.(2)Based on the high-throughput sequencing of the 16 S rDNA full-length region and the fungal ITS region,a total of 25807 bacterial OTUs and 2255 fungal OTUs were obtained from8 water samples.The microbial composition of samples from different sections was different.During the flood period(July),Limnohabitans(5.00%)was the dominant bacteria in the samples from the Moutai River section;Rhodosporidium(31.98%)was the dominant fungus.Compared with the samples from the Maotai River section,the composition of the bacterial microbial community in the samples from the Zhonghua River section was the most similar;For fungal microbial community,the samples from the Limin River section was closest.In the dry season(January),the samples from the Maotai River section was dominated by Armatimonas(26.48%);Rhodotorula was the dominant fungus.The microbial community composition of the samples from the Zhonghua River section was most similar to that of the samples from the Moutai River section.(3)Based on the high-throughput sequencing of the 16 S rDNA full-length region and the fungal ITS region,a total of 372 bacterial OTUs and 324 fungal OTUs were obtained.The community diversity of rice straw samples from Tianmenzhuang and Jinsha were lower.Therefore,selecting rice straw samples from Tianmenzhuan and Jinsha can reduce the influence of rice straw microorganisms on Daqu microorganisms during fermentation.(4)Using wheat from different typical regions to simulate Daqu making and measuring the flavor composition of Daqu,it was clear that the flavor compounds of Daqu was significantly different when using wheat from different typical regions.Daqu flavor compounds were detected by HS-SPME-GC-MS.The relative content of tetramethylpyrazine in sample LHKM-D was >80%,which was significantly higher than other samples;the relative content of 2,3-dimethyl-5-ethylpyrazine in sample XCM-D was prominent;the relative content of 2,3-butanediol and acetoin in sample YJM-D were respectively 3.13% and 0.63%,higher than other samples.(5)Based on the high-throughput sequencing of the 16 S rDNA full-length region and the fungal ITS region,the microbial community composition of 12 simulated Daqu samples was analyzed.For bacterial communities,Bacillus was the dominant bacteria.For fungal community,Alternaria,Epicoccum were the dominant fungal microorganisms.Compared with the sample from Guizhou,the bacterial microbial composition of the sample from Fuyang was the most similar.For fungal community,sample from Nanchong was the closest to the sample from Guizhou.