The Dynamical Variation Of Culturable Functional Bacterial Groups In The Fermentation Process Of Fen-flavor Xiaoqu Jingjiu And It's Effect On The Flavor

Traditional Fen-flavor Xiaoqu Liquor is an important part of Chinese distilled spirits.Xiaoqu was used as the fermentation starter,combining solid saccharification culture and solid fermentation production process.Jin Brand Fen-flavor Xiaoqu Liquor is one of the representatives of Fen-flavor Xiaoqu Liquor.It has more than 103 kinds of hydrophobic ingredients,and microorganisms play an important role in the fermentation process.Among them,The role of fungi is mainly saccharification and producing alcohol,while the function of bacteria is increasing flavor substances in wine.It is of great significance to explore the inherent relationship between various culturable functional bacteria groups and liquor flavor during the traditional fermentation process of Jin Brand Fen-flavor Xiaoqu Liquor.By the method of dilution culture,the culturable bacteria outfrom the traditional fermentation process of Fen-flavor Xiaoqu Jingjiu was divided into nine functional groups(protein-degrading bacteria group,starch-degrading bacteria group,cellulose-degrading bacteria group,lignin-degrading bacteria group,fat-degrading bacteria group,acetate-producing bacteria group,lactic acid-producing bacteria group,butyric acid-producing bacteria group and caproic acid-producing bacteria group)to explore their dynamical variation in the traditional fermentation process of Fen-flavor Xiaoqu Liquor in different seasons,and combined with the result of gas chromatographic of the liquor to explore the influence of culturable functional bacteria groups on the flavor of liquor.The main research contents and conclusions of this article are as follows:(1)Determination of physical and chemical indicators during fermentation.The temperature of the pit,the water content,acidity and reducing sugar content of the Zaopei sample.The result shows that the temperature trends of the pits in different seasons were similar.The initial fermentation temperature was about 15 ?-20 ?,then rose to about 30 ?,and changed slightly until the end of fermentation.There was no obvious difference in the change trend of the water content of the samples in different seasons.The water content was about 65% at the beginning,then increased to 70% to 75%,and basically remained stable until the end.There was significant difference between the acidity in different seasons.The trends of acidity in spring and autumn both increased first and then decreased,while the acidity in winter showed a continuous increasing,and the acidity in summer decreased firstly and then increased.There was significant differences in reducing sugar content in different seasons.The reducing sugar in autumn was basically stable at about 0.8%-1.0% during fermentation.The initial reducing sugar content in winter was close to 0.8%,and gradually decreased to about 0.6%,then rapidly increased to 2.1% at the end of the fermentation.The reducing sugar in the spring started at 0.45%,then increased to 0.8%,and fell to 0.45% at the end.In the summer,it was 1.62% at the beginning,then fell to 0.8% and then declined to0.4% at the end of fermentation.(2)Isolation and counting of culturable functional bacterial groups in samples.Different screening plates were used for the isolation and counting of total bacteria and various culturable functional bacteria groups in the samples.Finally Five types of functional bacteria groups were detected: acetate-producing bacteria group,lactic acid-producing bacteria group,butyric acid-producing bacteria group,starch-degrading bacteria group,and protein-degrading bacteria group.Acetic acid-producing bacteria,lactic acid-producing bacteria were the dominant functional bacteria.(3)Preliminary identification of representative functional strains.Sequence analysis of16 S r DNA was performed on 88 strains of functional bacteria.Among them,25 strains belong to Bacillus,51 belong to Lactobacillus,2 belong to Staphylococcus,3 belong to Streptomyces,3 strains belong to Pediococcus,2 strains belong to Pseudomonas,1 strain belongs to Cellulobacterium,1 strain belongs to Acetobacter.The macromolecular degrading bacteria are mainly Bacillus,while the acid-producing bacteria are mainly Lactobacillus.(4)Gas Chromatographic analysis of volatile flavor components in wine Samples.Gas chromatographic analysis of wine samples in different seasons shows that the contents of volatile flavor components in the wine samples in the four seasons had their own characteristics.In the wine sample of spring: the ethyl acetate content was highest(61.1mg/100 m L,the ethyl lactate content was the lowest(29.2 mg/100 m L),the acetal content is the highest(12.2 mg/100 m L),and the isoamyl alcohol content was the lowest(45.8 mg/100 m L).In the sample of summer: ethyl alcohol content was the lowest(8.1 mg/100 m L),the fusel oil content was the highest(219.2 mg/100 m L)and the total ester content was the lowest.In the sample of autumn: the total ester content was the highest(120.9 mg/100 m L),the isobutanol content was the lowest(7.3 mg/100 m L).In the sample of winter: ethyl lactatewas highest(71.3mg/100 m L),the total acid content is significantly higher than in other seasons(75.45mg/100 m L).(5)Correlation analysis.Redundant analysis and correlation analysis were performed to explain the relationship between the number of functional bacteria and the flavor components of wine.The results showed that the content of volatile flavor substances in the wine sample was significantly related to the functional bacterial community.Among them,lactic acid-producing bacteria were significantly related to the content of 4 esters,2 organic acids and 1 alcohol,while butyric acid-producing bacteria were significantly correlated to the contents of 2 esters,3 organic acids and 2 alcohols.The acetic acid-producing bacteria were significantly correlated with the contents of 2 esters,1 organic acid,5 alcohols and acetaldehyde.Redundancy analysis and correlation analysis between the physical and chemical indicators of samples and the total bacteria and the number of five functional bacteria show that: The total bacterial and functional bacterial populations of each season have no obvious characteristics.The physical and chemical indicators of samples and the total bacterial and five functional bacteria was significantly correlated.The number of butyric acid-producing bacteria was significantly correlated with water content and temperature.The number of acetic acid-producing bacteria,lactic acid-producing bacteria,and butyric acid-producing bacteria were significantly correlated with each other.The total bacteria and the number of lactic acid-producing bacteria were significantly correlated.This study explored the dynamical variation of culturable functional bacterial groups and physical and chemical indicators during the traditional fermentation process of Fen-flavor Xiaoqu Liquor in different seasons,and analyzed the internal relationship between the two and the flavor of the liquor.It helps depth research on fermentation mechanism of Fen-flavor Xiaoqu Liquor and optimization of production conditions.