Study On The Fermentation Of Pear Grain Co-leavened Distilled Liquor

The planting area and yield of pear in China were in the forefront of the world,and Hebei Province was the main pear producing area in China.At present,pear mainly ate directly,its further processing ability was relatively weak.Pear wine,as one of the deep processing methods of pear,had great development potential.However,there were many problems in the market,such as weak taste,which led to its low market share.In contrast,China's traditional Baijiu was popular among consumers because of its flavor and taste,and it occupied a relatively high proportion in the wine industry market in China.In order to make up for the defects of pear wine in taste and flavor,and make it more in line with the market demand,this paper integrated the advantages of Chinese traditional solid liquor brewing and fermented pear wine,and produced a new distilled wine with both the fresh and elegant flavor of pear wine and the mellow and rich taste of white wine by means of the method of pear grain fermentation.Firstly,the brewing technology of pear grain co fermented distilled liquor was optimized by orthogonal test,secondly,the distilled liquor prepared under the optimal conditions was analyzed,and the volatile flavor compounds were analyzed by gas chromatography-mass spectrometry;finally,the microbial diversity of fermented grains of pear grain co fermented distilled liquor was analyzed by high-throughput sequencing technology.The main results were as follows.(1)Study on the process of pear grain fermentation.The optimal parameters of each fermentation process were determined by single factor experiment.On the basis of single factor,orthogonal test was conducted with the addition amount of pear juice,grain grains ratio and Daqu amount as independent variables.The results showed that the addition amount of pear juice(according to grain quality)was 15%,the ratio of grain grains ratio was 1:2.3,and the addition amount of Daqu(according to grain quality)was 30%.Under the optimized conditions,the sensory score of the distilled spirit was 92,the liquor yield was 27.86%,the total ester content was 2.1584 g/L,and the total acid content was 1.4675g/L.(2)Analysis and evaluation of volatile components in the distilled wine from pear grain.Under the optimal brewing conditions,46 kinds of volatile components were identified,and the total content of volatile components was about 4.711 g/L,including 20 kinds of esters,12 kinds of alcohols,8 sorts of acids,5 kinds of aldehydes and so on.And for the odor activity value(OAV)greater than 1,There were 22 flavor compounds,such as acetic acid,caproic acid,iso-valeric acid,ethyl acetate,ethyl caproate,ethyl oleate,ethyl palmitate,etc.The chromatographic framework composition of the pear grain co-fermented liquor was basically the same as that of the traditional Chinese liquor.It was a new type of distilled liquor with a unique style,which combined the aroma and flavor characteristics of the traditional Chinese liquor and pear wine.(3)Comparative analysis of microbial diversity in fermented grains from pear grains.Under the optimal brewing conditions,the changes of microbial composition in fermented grains from pear grains were compared and analyzed.The results showed that the dominant bacteria in fermented grains were Ruminococcaceae,Acinetobacter,Muribaculaceae,Lactobacillus and Azospirillum.And the fungi were Phialemoniopsis,Echria,Alternaria,Didymella,Monascus,Dokmaia,Botryotrichum,Aspergillus,Mortierella,and Candida.Compared with fermented grains without pear juice,the abundance of Lactobacillus in fermented grains was significantly increased(P<0.05),the abundance of Azospirillum was significantly decreased(P<0.05),Fungi that are growing in abundance include Botryotrichum,Aspergillus,Mortierella,Candida,Cutaneotrichosporon,Thermomyces.In addition,the change of dominant flora also had a certain degree of influence on the composition and content of flavor.