Spatial Difference Analysis Of Pit Mud And Preparation Of High Butyric Acid Flavored Liquor

As the fermentation equipment of Luzhou-flavor liquor,the pit mud was closely related to the quality of Luzhou-flavor liquor.Pit mud was rich in a variety of fermentation microorganisms,which can produce important aroma components and their precursors in the flavor of the liquor.By screening the functional microorganisms of pit mud,studying their metabolites and their metabolic pathways,and applying them to the biological enhancement of pit mud,it is of great significance to improve the quality of pit mud and the development of artificial pit mud.It provides theoretical and technical guidance for the regulation and control of liquor flavor.In order to study the spatial distribution difference of microorganisms and volatile compounds in pit mud,Illumina Mi Seq sequencing was used to analyze the composition of microbial community in pit mud,and solid phase microextraction(SPME)coupled with gas chromatography-mass spectrometry(GC-MS)was used to qualitatively and quantitatively analyze the main volatile compounds in pit mud.A total of 10 phyla,15 classes,21 orders,42 families,and 64 genera of prokaryotic microorganisms were detected in the pit mud samples.The dominant flora accounted for 98.86%～99.93% of the total number of bacteria at the phylum level,and Firmicutes was the absolute dominant flora.The volatile components in the pit mud were mainly esters and acids,accounting for 73.01%to 98.36%.The spatial distribution is as follows: from top to bottom,with the increase of pit depth,the proportion of esters in volatile substances increased from 7.68% to 76.35%,and the proportion of acids increased from 4.08% to 19.37%.The abundance and diversity of microflora gradually increased from top to bottom,which was consistent with the distribution of volatile substances.The dominant bacteria such as Clostridium and Methanobacteria are the main microorganisms that carry out microbial metabolism and interspecific material exchange,produce important aroma substances and their precursors,and enrich continuously with the increase of spatial depth.The formation of the law closely related to the spatial position of pit mud.The spatial difference is an important reason for the difference of prokaryotic microflora and volatile substances in different spatial positions of pit mud.Butyric acid-producing bacteria were screened and isolated from pit mud by electric field-assisted screening device.Through the molecular biological identification of the strains and the study of acid production,it was determined that all the three butyric acid-producing bacteria were Clostridium butyricum.Among them,Clostridium tyrobutyrate W-1 had the better ability to produce butyric acid.Clostridium butyricum was anaerobes and the main product was butyric acid.Through the preliminary study on the acid production capacity of Clostridium tyrobutyrate fermentation,it was found that the butyric acid production capacity of Clostridium tyrobutyrate could be improved by adding exogenous ethanol in a certain concentration range.However,the addition of acetic acid could not increase the yield of butyric acid.The optimal culture conditions of Clostridium tyrobutyricum W-1 strain were studied,and it was determined that the maximum biomass could be achieved under the conditions of 9% inoculum,initial medium p H of 6.4 and culture temperature of 37 ℃.The solid-state brewing of Luzhou-flavor liquor was carried out in the experiment pit,and the prepared Clostridium tyrobutyricum solution was sprayed in the process of distiller’s grains,fermented grains,pit mud and mixing Daqu powder for fermentation,and a high butyric acid seasoning liquor was finally obtained.The relative content of total acid in high butyric acid flavored liquor increased by 26.15%,in which the content of butyric acid increased by1.66 times,the content of total ester increased by 14.51%,and the content of total higher alcohol decreased by 0.88%,all in line with national standards.