Application Of Bioaugmetation Aspergillus Niger And Acetobactar Pasteurianus In Sichuan Bran Vinegar In Solid State Fermentation Process

Using a mixture of uncooked materials and multi-strain open fermentation mode,deeply colored,rich fragrance and well tasted Sichuan bran vinegar is made from wheat flour,wheat bran as major ingredients.However,the traditional solid-state fermentation has some issues such as underutilization of starch,low productivity and long fermentation period.Compared to the control group of natural fermentation,the experiment groups with Aspergillus niger and acetobacter bran-koji based on bioaugmentation methodology was set up to investigate the variable parameter of starch content of Sichuan bran vinegar,total acid et al.Combined with flavor compounds determination and microbial diversity analysis,the purpose of this thesis was to investigate the quality of Sichuan bran vinegar using bioaugmentation methodology.The major conclusions are summarized below:1?Adopted with strains AS 3.758 and C9-4 as bioaugmentation strain,the producing conditions with fungus age 2.93 days,water added 79.55%,inoculum dose 3.3 × 104 can be obtained by single factor test and response surface Box-Behnken experimental design.In this condition,the value of saccharification ability reaches 4653.194 mg/g.The producing conditions of C9-4 bran-koji are water content 90%,acetic acid 0.5%,ethanol concentration 1%,inoculum dose 6%.In this condition,a total number of acetic acid bacteria reached 2.69 × 108(value of the log is 8.43).2?A control group with natural fermentation and two experimental groups with only Aspergillus niger bran-koji and both Aspergillus niger and acetobacter bran-koji were conducted for this research.After fermenting,the total acids of experimental groups were 4.66 g/100g and 4.62 g/100g,respectively,which significantly increased vinegar productivity compared to the 3.04 g/100g for the control group.The starch content of control group,with only Aspergillus niger bran-koji experimental group and with both Aspergillus niger and acetobacter bran-koji experimental group reduced from 14.77%,14.6%and 14.54%to 7.23%,5.08%and 4.85%with starch utilization ratio of 51%,65.2%,and 66.6%,respectively.In conclusion,use of bioaugmentation methodology by adding Aspergillus niger and acetobacter bran-koji significantly increased the utilization ratio of starch and vinegar productivity of Sichuan bran vinegar.3?Compared the experimental groups and control group,in terms of the contents of organic acids,organic acids,free amino acid and volatile substance in the raw and cooked vinegar,it is found that the highest component is lactic acid,followed by acetic acid and these two acids have more than 90%components.The content of organic acids in experimental groups significantly increased than the control group.There are many types of free amino acids in Sichuan bran vinegar,and the top five components are glutamic acid,alanine,valine,leucine,and proline.The contents of free amino acid in experimental groups are higher than the control group,as well as histidine and tyrosine,which increased functional factor.During fermentation of Sichuan bran vinegar,many types of esters were produced.The most proportions of esters are hexanoic acid ethyl ester and Octanoic acid ethyl ester,which are the components of principle fragrance.Acetic acid and Furfural have more than 65%content,which are the principle components of fragrance.The components of fragrance in the experimental group are similar to components in the control group,retained the typical fragrance components.In conclusion,the experimental groups with bioaugmentation are able to contain the typical flavor of Sichuan bran vinegar and taste better.4.Some conclusions could be obtained from microbiological diversity analysis using high-throughput sequencing method during fermentation of Sichuan bran vinegar.Sichuan bran vinegar contains abundant mycelium.After bioaugmentation,there was no obvious difference observed for community structure.During the fermentation,the principle bacteria such as Actinobacteria,Alphaproteobacteria,Betaproteobacteria,Gammaproteobacteria,Bacilli,Sphingobacteriia and fungus such as PezizomycetesWallemiomycetes?Agaricomycetes?Dothideomycetes?Eurotiomycetes?Leotiomycetes?Saccharomycetes?Sordariomycetes?Tremellomycetes were included in class.There were abundant contents and types of lactobacillus and yeasts during fermentation.The results showed that bioaugmentation of Aspergillus niger and acetobacter bran-koji significantly improved the utilization of starch,the productivity of vinegar.Meanwhile,flavor character tested results also showed that with bioaugmentation experiment is able to ensure typical tasty of Sichuan bran vinegar and improve acetic acid content as well as free amino acid content.