Isolation,Identification And Characterization Of Aerogens From Traditionally Fermented Broad Bean Paste

The aerogenesis defect was defined as the production of gas in broad bean paste.This will increase waste,reduce consumers' confidence and cause economic losses.In this study,aerogenic broad bean paste samples were studied and compared.An aerogen was isolated and identified from aerogenic sample and its properties were characterized.Verify experiment of gas producing ability was performed by inoculating the aerogen back into broad bean paste.Finally,the effect of three inhibitors on the growth of aerogen was tested.The results are showed as follows:1.Compared to normal sample,the aerogenic sample had a kind of off-odour and acerb taste.In quality characteristics,the pH value and amino acid nitrogen concentration were decreased by 0.52 and 0.42 g·100mL^-1,respectively while the concentration of total acid was increased by 1.600 g·100mL^-1.In microbial community,proteobacteria bacteria are more abundant in aerogenic sample while firmicutes bacteria were more abundant in normal sample.2.An aerogen was isolated from aerogenic sample and identified as B.licheniformis FHYM 8.It's facultative anaerobic microorganism with high tolerance against high temperature,low-pH and high salinity environment.Its growth was observed under 15% salinity environment in aerobic cultivation and 13% salinity environment in anaerobic cultivation.It could survive after 100? disposal for 10 min and when it was cultivated at pH 3.8.The anaerobic metabolites of B.licheniformis FHYM 8 consisted of lactic acid,ethanol,2,3-butanediol and CO2.3.The gas producing ability of B.licheniformis FHYM 8 in broad bean paste was confirmed.The total acid concentrations in aerogenic broad bean paste samples were higher than that in normal samples.B.licheniformis FHYM 8 showed the ability to produce gas when the broad bean paste was sterilized at 66? while no gas was produced when B.licheniformis FHYM 8 was inoculated in broad bean paste after the sterilization process,indicating that heat treatment was the necessary step for B.licheniformis FHYM 8 to produce CO2 in broad bean paste.4.The minimal inhibitory concentrations?MICs?of nisin,sodium benzoate and sodium propionate on B.licheniformis FHYM 8 were 0.16 mg×mL^-1,8.00 mg×mL^-1 and 20.00 mg×m L^-1 in normal MRS medium while the MICs of the three substances were decreased to 0.02 mg×mL^-1,1.00 mg×mL^-1 and 5.00 mg×mL^-1,respectively,in high salinity?8%?medium.5.A strain of B.tequilensis named HYM 42?CGMCC NO.12092?was selected from dominant bacteria in broad bean paste and proved to be able to inhibit the growth of aerogen.