| In this experiment,the amylase,acid protease and cellulase-producing Bacillus were isolated from the fermentation stage of Shanxi aged vinegar.Through environmental tolerance tests and enzyme production performance tests,Three dominant enzyme-producing Bacillus and Aspergillus niger AS3.4309 were selected to make compound Fuqu,The compound Fuqu and Daqu were applied to the fermentation stage of Shanxi aged vinegar.The purpose was that increased the utilization of starch and protein in the fermentation process and reduce the amount of Daqu,finally,improved the quality of vinegar products.The specific test results were as follows:(1)The Jiulao and Cupei which from the fermentation stage of Shanxi aged vinegar were isolated 18 strains enzyme-producing Bacillus through primary screening and rescreening,there were 6 strains of amylase-producing Bacillus,6 strains of acidic protease-producing Bacillus,and 6 strains of producing-cellulase Bacillus.8 strains of Bacillus with good enzyme-producing ability were screened by environmental tolerance tests,the numbers were JT10-9,JT4-4,CT32-3,CD92-3,CD33-4,JD7-7,JX4-13,and CX9-3 respectively.(2)Eight enzyme-producing strains were tested for enzyme production performance,screening three target strains with high enzyme activity that could secrete amylase,acid protease and cellulase simultaneously which were JT10-9,CD33-4 and JX4-13 respectively.Through morphological observation,physiological and biochemical test results and 16S rDNA analysis of strains JT10-9,CD33-4,and JX4-13,The strains JT10-9 and CD33-4 were identified as Bacillus amyloliquefaciens and the strain JX4-13 was Bacillus subtilis.The optimum mixing ratio of Bacillus JT10-9,CD33-4 and JX4-13 in the mixed culture system was determined to be 2:1:2 by orthogonal design.(3)Single factor and uniform design were applied to optimize the conditions for making compound Fuqu:The difference between the time of addition of the Bacillus combination and Aspergillus niger AS3.4309 was 28 hours,cultivation temperature 34?,Bacillus combinated inoculum was 4%.By comparing the performance of compound Fuqu and common Fuqu,compound Fuqu was not only rich in aroma but also The enzyme activity of glutenase,acid protease and cellulase of compound Fuqu which was inoculated with Bacillus combination increased by 26.64%?47.03%and 44.86%,respectively,compared with that of common Fuqu which was inoculated with Aspergillus niger AS3.4309.(4)Using HS-SPME combined with GC-MS to analyze the volatile components of compound Fuqu and common Fuqu,there were 30 kinds of volatile compounds in compound Fuqu and 28 kinds of volatile compounds in common Fuqu.2-methyl-1-butanol,1-octen-3-ol,?-phenylethanol,phenylethyl acetate,acetic acid,5-methyl-2-phenyl-2-hexanal,4-vinyl The relative content of guaiacol,guaiacol,and other components were higher than that of common Fuqu.In addition,3-hydroxy-2-butanone(acetoin)and 2,3,5,6-tetramethylpyrazine were detected in the compound Fuqu.(5)On the basis of single factor experiments,response surface methodology was used to optimize the alcohol fermentation of Shanxi aged vinegar,the optimized alcohol fermentation process conditions were that the total amount of Daqu and compound Fuqu was 51.48%?The liquid to material ratio was 3.46:1?the fermentation time was 11.5 d.,the alcoholicity of Jiulao was 9.8%vol,which was not significantly different from the prediction of 9.62%vol.Fermentation conditions optimized by response surface method were used for vinegar brewing.Compared with the traditional fermentation process,the utilization rate of starch and protein in Juliao and the utilization rate of starch and protein in Cupei.compared with the traditional process were respectively increased by 124.95%,6.50%;27.48%,8.49%.The content of total acid,non-volatile acid,reducing sugar and amino acid peptide nitrogen in the physical and chemical indexes of new vinegar was significantly higher than the traditional technology,which was 18.67%,43.82%,48.12%,and 18.75%,respectively. |
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