Analysis Of Microflora And Flavor Compounds In The Production Of Special-flavor Liquor

Chinese liquor has a long history and deep culture.Special-flavor liquor is one of the aroma style of traditional liquors.It gives a pleasant flavor characterize of aroma and a unique role by unique production and fermentation technology in china distilling liquor.Different from other flavor type liquors,the main raw material of special-flavor liquor is rice,and renewal materials are mixed with steam during the distilling process.A portion of the heads and the ends of distillates are moved out to improve the liquor quality.Next,the fresh distillates were aged and blended to product liquor.However,there is little study carried out to analysis the aroma compounds and the brewing mechanism in special-flavor liquor,so it is still unclear about its fermentation mechanism and characteristic flavor compound.Thus leads to a lack of scientific theories for special-flavor liquor production.So,it is the key factor for special-flavor liquor to analyze microbial and volatile aroma compounds.In this paper,culture-dependent and high-throughput sequencing technology were employed to analyze the microbial structure of Daqu,Jiupei,Dizao of special-flavor liquor.In this research,headspace solid phase micro extraction(HS-SPME)and gas chromatography mass(GC-MS)technology were used to detect the changes of flavor compounds in Jiupei during the brewing stages and volatile flavor in base liquors after distilled.Multivariate statistical analysis was used to analyze the characteristic flavor compounds in Jiupei during different stages and different base liquors.This study served as a theoretical underpinning for exploring the fermentation mechanism of special-flavor liquor.The main results showed as follows:1.Bacterial communities analysis showed that Bacillales,Lactobacillales,Rhodospirillales,Saccharomycetes and Eurotiales were the predominant orders in matured special-flavor starter.Bacillales and Eurotiales were the predominant orders in inner of matured starter,Rhodospirillales and Saccharomycetes were concentrated distribution in surface of starter sample.Lactobacillales was uniform distribution whether surface or central samples.2.Bacillales,Lactobacillales,Rhodospirillales,Micrococcales,Saccharomycetes and Eurotiales were the predominant orders in the initial stage of fermentation,Lactobacillales and Saccharomycetes were the prevailed orders in the late brewing stage.The relevance of the results showed that Lactobacillus and Saccharomyces were functional microbes during fermentation process of special-flavor liquor,and their microbial community structure not changes with a change of the pits depth.Combined with the change of physicochemical parameters,the results of decrement of sugar,content of total nitrogen,p H and temperature showed positively correlation with bacterial composition at early stage of the liquor fermentation period;the results of total acidity and alcoholic strength showed positively correlation with bacterial composition at last stage of liquor brewing.Total acidity and alcoholic strength correlated positively with the predominant orders of Lactobacillales and Saccharomycetes,respectively.3.Acids,alcohols,and esters were a large proportion of volatile flavor contents in Jiupei during brewing process of special-flavor liquor.The content of esters was the highest,while acids the lowest.The contents of volatile compounds in upper layer were highest than bottom layer,but the changing trends of aroma compounds were similar between the upper and bottom layer of Jiupei at the end of fermentation.The results of PCA showed that: there is no aroma compounds were detected from samples at 0～3 days.Octanoic acid ethyl ester,heptanoic acid ethyl ester,ethyl caproate,pentanoic acid ethyl ester,ethyl benzene acetic acid,hexadecanoic acid ethyl ester,and butanediol were characteristic flavor compounds from samples at 6～15 days.Ethyl acetate,ethyl butyrate,succinic acid ethyl ester,phenyl ethyl acetate,pelargonic acid ethyl ester,ethyl decanoic acid,lauric acid ethyl ester,nutmeg acid ethyl ester,15 acid ethyl ester,ethyl oleate,linoleic acid ethyl ester,hexanoic acid,hexadecanoic acid,diethylene glycol,isoamyl alcohol,phenylethyl alcohol,isoamyl acetate,ethyl stearate were characteristic flavor compounds from samples at 20～30 days.The results showed that the flavor matter were accumulated at the end of fermentation,so prolonging fermentation period contributed to enhance flavor of special-flavor liquor.4.The optimal condition of HS-SPME for extracting aroma compounds in base liquor were 10 m L 5% alcohol liquor with 2g Na Cl at an extraction temperature of 50℃ for 30 min.103 kinds of aroma were detected in all base liquor samples.The most of esters concentrated in the head liquor,while the content of Alcohols,phenols,acids,aldehyde and ketone were high in the tail liquor.PCA showed that: isoamyl alcohol,ethyl acetate,isoamyl acetate,ethyl oleate,ethyl caproate,heptanoic acid ethyl ester,octanoic acid ethyl ester,hexanoic acid ester,hexanoic acid ester and ethyl butyrate were characteristic flavor compounds of head and body liquor;phenylethyl alcohol,benzene acetaldehyde,furfural,4-ethyl guaiacol,2,4-2ethyl tertiary butyl phenol,pentanoic acid,formic acid,octyl ester,ethyl benzoate,caproic acid butyl ester,benzene,phenyl ethyl acetate,ethyl acetate,8-nonene acid ethyl ester,pelargonic acid ethyl ester,ethyl decanoic acid and lauric acid ethyl ester,ethyl myristic acid,palmitic acid ethyl ester and linoleic acid ethyl ester were characteristic flavor compounds of tail liquor.