| For Shanxi age vinegar,the quality of Daqu is an important guarantee of excellent products.Daqu is rich in microbial system,which is influenced by its unique production technology to a great extent.In this study,traditional strain isolation combined with ITS sequencing and construction of systematic evolutionary tree were used to study the difference of mold community structure in Daqu from five different manufacturers of Shanxi old vinegar.The basic physical and chemical properties(temperature,total acid,reducing sugar)of Daqu were studied.Starch,water,amino nitrogen,protease,Glucoamylase,cellulase)organic acids,volatile aroma components to explore the relationship between starch,water,amino nitrogen,protease,Glucoamylase,cellulase)organic acids and mold community,at the same time from Shanxi old vinegar Daqu separation screen Three excellent strains producing protease,Glucoamylase and cellulase were selected and optimized.The results are as follows:The difference of microorganisms in different Shanxi old vinegar Daqu was studied by traditional strain isolation method.The results showed that the total number of bacteria in five kinds of Shanxi old vinegar Daqu was significantly different,and the highest C vinegar factory Daqu was 9.86×1013cfu / g,the highest was 9.86×1013cfu/g,and the highest was 9.86×1013cfu / g.There was no significant difference in the number of yeast among the five kinds of Daqu,and the number of yeast in C Daqu was the most,which reached 1.57×1012cfu / g.In the same way,the maximum number of molds in Daqu was 8.5×1018cfu/g.C,which was significantly different from that in other Daqu.Using traditional method of bacteria isolation and combining with modern molecular biology technology to treat Shanxi age vinegar a total of 10 species of mold were detected,among which Rhizopus miltiorrhiza 23.71% was the first dominant bacteria,and the average proportion of total transverse mildew in all samples was 22.22%,which was the second dominant bacteria.The other relatively large proportion were Aspergillus flavus 22.01% and Aspergillus nigra21.31%.The most dominant mold in A Daqu was Aspergillus nigra,accounting for 22.16% of the total mold in A Daqu.Aspergillus nigra was the first dominant bacteria in Daqu,accounting for 28.66%.Aspergillus nigra was not detected in E Daqu,and the first dominant bacteria was 48.46%.In B Daqu,the rate of Aspergillus nigra was 48.46%.The most dominant strain was Aspergillus flavus 40.51%,followedby Rhizopus miltiorrhiza 34.48%.The first dominant strain in D Daqu was Aspergillus flavus 30.25%.(2)the total acid and amino nitrogen content of C Daqu in Shanxi old vinegar Daqu from five different manufacturers were 1.77g/100 g and 0.76g/100 g,respectively.The highest protease activity was C Daqu up to 54.31U/g,which was produced by Aspergillus nigra during metabolism.The highest activity of Glucoamylase in D Daqu was 591.68U/g,and the number of Aspergillus niger and Aspergillus flavus in C Daqu was higher.It was speculated that Aspergillus in Daqu was the main source of glucoamylase activity.The highest cellulase activity was 93.95U/g in C Daqu,followed by 9011U/g in D Daqu,and the fiber between the two kinds of Daqu was the highest.There was no significant difference in enzyme activity(P>0.05).The number of Aspergillus flavus in D Daqu was more than that of Aspergillus flavus.It was speculated that the cellulase activity was related to Aspergillus flavus.The esters detected in A Daqu were the most volatile compounds,with a total of 18 kinds.The total content of esters in 1.6288mg/g.B Daqu was the highest among five kinds of Daqu,reaching 2.9141 mg /g.In B Daqu,the highest content of isoamyl acetate in 14 kinds of esters was 0.3056 mg/g,and in B Daqu,the highest content of isoamyl acetate was 0.3056 mg/g.And the content of these two substances in B Daqu is higher than that in the other four samples.The ester content in C Daqu is 0.7784 mg/g,the highest content of butyl acetate in fruit flavor was the highest content in 0.1369mg/g.E Daqu,and the highest content of ester in Daqu was L(-)-ethyl lactic acid,which had a strong aroma of alcohol,which was 0.24 mg/g,L(-)-ethyl lactic acid,which was0.24mg/g.However,there were only two kinds of esters in E Daqu.The total content of organic acid in C Daqu was the highest,which was 3.2998g/100 g,followed by D Daqu was 2.2726g/100 g,and the highest lactic acid content was C Daqu(0.4556g/100g).The quality of C Daqu and D Daqu is excellent.(3)The high yield protease strain Aspergillus flavus SAV896-2,glucoamylase producing strain SAV186 and Aspergillus flavus SAV774,were isolated and screened from Shanxi vinegar Daqu and cultured in the basic medium of enzyme producing liquid fermentation.The conditions and medium of protease production,glucoamylase and cellulase were optimized.The results showed that when the conditions were barley pea 6%,ammonium chloride 0.5%,initial p H 6,liquid volume 75 m L,rotating speed 165r/min,inoculum size 8 days,Aspergillus flavus SAV896-2 grew best and laid eggs.The highest white enzyme(55.08 U/m L),4% of bran,1.0% of sulfuric acid,7 of initial p H,100 m L of liquid loading,145r/min of rotation speed and 8% of inoculation amount,the activity of Aspergillus niger SAV186 was the highest(852.98 U/m L),and the addition of bran was 2% and the sulfate content was 1.5%.The initial p H was 7,the amount of the solution was 75 m L,the rotational speed was 165 r/min,and the inoculum size was 8% for 7 days,and the activity of the Aspergillus flavus SAV774 was the highest(272.11 U/m L).Aflatoxin SA The activity of the protease V896-2 increased by 16% compared with the initial proteaseactivity,the activity of the Aspergillus niger SAV186 glucoamylase increased by 25%,and the activity of the Aspergillus flavus SAV774 was about twice that of the prior art,and was a supplement to the study on the high-yield enzyme strain of the vinegar in Shanxi. |
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