Selection Of Excellent Fermentation Strains And Optimization Of Fermentation Process Of Boza In Xinjiang

In this study,the isolation and identification of yeasts and lactic acid bacteria from the traditional fermented Boza in different areas of Xinjiang,Molecular identification and analysis of some strains,screening the Boza stable fermentation strains with fermentation characteristics,and the Boza traditional and the new fermentation process,the test results were as follows:1.Barley,millet,corn three grains were used as raw materials,through the response surface method to determine the optimum fermentation condition of natural fermented Boza,results showed that the fermentation temperature was 30.8?,the enzyme preparation was 3.25%,the Second fermentation time was 29 h,raw material ratio was Barley: millet: Corn(1:2.5:1.5).under the condition of Boza Alcohol content 3.67±0.06%(v/v),Total sugar 8.7±0.29 °Bx,Sensory evaluation can up to 88.33±2.08.2.30 strains of yeasts were isolated from Boza which was gathered from places such as Xinyuan,Tekesi,Aketao,Yining,Urumqi(natural fermentation Boza made by Xinjiang Agricultural University)in Xinjiang.According to the morphological characters,physiological and biochemical properties,25 strain was identified as cerevisiae;4 strain was identified as Pichia;and 1 strain was identified as Cryptococcus.The 11 representative strains(Y1,Y2,Y4,Y5,Y8,Y9,Y11,Y12,Y19,Y23,Y34)of yeasts isolated from Boza were identified by molecular biology,results showed that Saccharomyces cerevisiae,Pichia fermentans,Pichia membranifaciens,In addition to Y9,Y11 strains,the similarity of the comparative strains and strains in the NCBI database were greater than 94%.3.16 strains of lactic acid bacteria were isolated from Boza which was gathered from places such as Xinyuan,Tekesi,Aketao,Yining,Urumqi(natural fermentation Boza made by Xinjiang Agricultural University)in Xinjiang.According to the morphological characters,physiological and biochemical properties,1 strain was identified as Weissella confusa;5 strain was identified as Pediococcus pentosaceus;2 strain was identified as Lactococcus;6 strain was identified as Lactobacillus plantarum;and 2 strain was identified as Lactobacillus rhamnosus.The 8 representative strains(L1,L2,L4,L9,L10,L12,L14,L15)of lactic acid bacteria isolated from Boza were identified by 16 S rDNA sequence analysis,results showed tha Weissella confuse,Pediococcus pentosaceus,Lactobacillus plantarum,Lactobacillus rhamnosus,the similarity of the comparative strains and strains in the NCBI database were greater than 96%.4.The 6 strains of yeast and the 6 strains of lactic acid bacteria were isolated from Boza as the tested strains,Based on the screening single strain and complex microbial agents with analyzing the indicators of ethanol,total acid,tolerance test,fermenting power and growth conditions in the liquid medium,the Saccharomyces cerevisiae(Y8)and Lactobacillus plantarum(L9)were proved to be suitable for the fermentation of Boza.5.Use the orthogonal test method to investigated the liquefaction and saccharification process of starch before fermentation for producing Boza,results showed that ?-amylase amount of 0.11%,pH 6,liquefaction time of 50 min,liquefaction temperature of 65?,under the condition,the final DE of the hydrolyzate 32.6%;?-amylase amount of 0.01%,pullulanase amount of 40 ?l,pH 5.5,saccharification temperature of 58?,saccharification time of 2 h,under the condition,the final DE of the hydrolyzate 79.42%.Yeast and lactic acid bacteria isolated from Boza were used as mixed starter culture,through the response surface method to determine the best technology of fermented Boza,results showed that the mixed fermentation temperature was 30?,the mixed fermentation time was 33 h,mixed inoculum size was 2%(Yeast and lactic acid bacteria ratio 1:1).Under the condition of Boza Alcohol content 3.4±0.1%(v/v),Sensory evaluation can up to 82±0.5.