Effects Of Multiple Rounds Of Aspergillus Niger Bran Koji Intensification Technology On Microbial Flora And Flavor Quality During The Solid Fermentation Of Sichuan Bran Vinegar

This article takes Sichuan bran vinegar as the research object,explores the effects of multiple rounds of biological fortification on the index of Sichuan bran vinegar starch utilization and total acid content of vinegar,and simultaneously analyzes the flavor substances and microbial diversity.The main results are as follows:1.Using Aspergillus niger As 3.758 as the fortified strain,set different addition amounts of Aspergillus niger bran.The results showed that when the addition amount of Aspergillus niger bran was 0.6%(w/w,based on the total amount of raw materials input during fermentation),its starch utilization rate and total acid content of vinegar were up to 51.46%and 4.03g/100g.Therefore,the amount of Aspergillus niger bran added was determined to be 0.6% during multiple rounds of bio-enhanced fermentation in the later stage.2.At the end of multiple rounds of fermentation,the total acid content of vinegar in the control group was 3.36g/100g in the first round,3.90g/100g in the second round,and 3.64g/100g in the third round;the total acid content in the test group was 3.64g/100g;The first round was 3.90g/100 g,the second round was 4.25g/100g,and the third was 4.11g/100g.The total acid content of vinegar in the test group increased by about 10% on average.The starch content of the control group decreased from 12.60% to 5.70% in the first round,13.35%to 5.12% in the second round,and 12.53% to 6.00% in the third round.The starch content in the test group decreased from 13.00 in the first round.% Dropped to 4.77%,the second round of 13.24% fell to 3.61% and the third round of 12.37% fell to 4.69%,the average starch utilization rate of the experimental group increased by about 9.8%.It can be seen that the use of biological fortification technology to introduce Aspergillus niger bran koji can significantly improve the total acid content and starch utilization of Sichuan bran vinegar vinegar.3.The analysis of free amino acids in the cooked vinegar samples after multiple rounds of fermentation showed that the total amount of free amino acids obtained from the multi-round fermentation of vinegar in the first round of the control group was 2979.38mg/100mL and the second round was 2302.26mg/ 100mL and the third round were 2468.39mg/100mL,with an average value of 2252.67mg/100mL;in the experimental group,the first round was 2936.62mg/100mL,the second round was 2407.35mg/100mL,and the third round was 2333.55mg/100mL,the average value is 2559.17mg/100mL,and the histidine content is significantly higher than the control group.Comparing the volatile substances of fermented vinegar samples and raw and cooked vinegar samples between the control group and the test group showed that there was no significant difference in the types and contents of aroma components between the control group and the test group during multiple rounds of fermentation.During the fermentation process of the control group and the test group,the ethyl ester compounds used ethyl caproate and ethyl octanoate as the main ester compounds,and their contents were much higher than other ester substances;in the test group,the ester substance diethyl succinate ester and propyl octanoate were detected but almost did not appear in the control group.These lower esters also increased the aromatic flavor of vinegar;the phenylethanol content in the cooked vinegar in the multi-round fermentation test group was significantly higher than that in the control group.The fragrance is a certain improvement;the carbonyl compounds are mainly furfural.4.High-throughput sequencing of vinegar samples in the multi-round fermentation process of Sichuan bran vinegar showed that the structure of Sichuan bran vinegar flora is rich,and multiple rounds of biological enhancement have a certain impact on the structure of the experimental group.During the multiple rounds of fermentation,both the control group and the test group were the two most abundant auricles Firmicutes and Proteobacteria in all samples,and there was no significant difference in the door level;the level Compared with the control group and the experimental group at the beginning of fermentation and the end of fermentation at the end of the fermentation of two species of genus found at the end of the fermentation genus is mainly Lactobacillus,Acetobacter and Bacillus three kinds.The relative abundance of Lactobacillus in the test group at the same fermentation stage was increased compared with the control group,especially the relative abundance of Lactobacillus in the test group was significantly higher than that in the control group,indicating that the fermentation process after adding Aspergillus niger The structure of the bacteria in the bacteria has an impact on the structure of the bacteria.The Ascomycota and Basidiomycota are the two most abundant phylums in the fungal phylum of all samples.The Ascomycota phylum is the most abundant phylum throughout;the most abundant genera of the control and test groups are: Saccharomyces,unclassified-p-Ascomycota and Aspergillus Genus.Saccharomyces and Aspergillus are the most dominant fungi in the fermentation process of Sichuan bran vinegar,and their types and numbers are significantly higher than other fungi.After biofortification,the number of Aspergillus in the experimental group during the fermentation stage was significantly higher than that in the control group,and Aspergillus niger belongs to the genus Aspergillus,indicating that the addition of Aspergillus niger bran koji has a certain impact on the flora of Sichuan bran vinegar.