Analysis Of The Effect Of Fine Bacteria On The Composition Of Flora In Fermented Sausage

This research was aimed at analyzing the microflora of Jinhua ham and Xuanwei ham at different period by using high-throughput sequencing. Basing on the analysis results, the primary microorganisms were isolated and screened. Further more, they were used as started culture for product validation by sausage fermentation. And then, PCR-DGGE was used for studying the dominant bacterial community at different fermentation stage. In addition, the texture and sensory were determined at the fermentation anaphase. The final purpose of the article is in order to study the mechanism of change in flora and provide the theoretical foundation for starter culture exploiting. The main results of the research as follows:(1) The total DNA of microbes were extracted from Jinhua ham and Xuanwei ham, and amplified on 16S rDNA V3 region and then were studied by Illumina MiSeq high-throughput sequencing. The results showed that OUT of the four ham samples could be divided into 1600 groups. And the microflora could be divided into 26 groups on the level of phylum which mainly included Firm cutes and Proteobacteria. On the level of class, they could be divided into 56 groups. There were 69 groups on the basis of orders and 138 groups on the level of families which mainly contained Planococcaceae, Staphylococcaceae, Leuconostocaceae, Lactobacillaceae, Bacillaceae 1 and Moraxellaceae. And they could be classified into 265 groups on the basis of genus which principally contained Citrobacter spp., Psychrobacter spp., Kurthia spp., Staphylococcus spp., Yersinia spp., Weissella spp., Lactobacillus spp. and Bacillus spp. Among the samples, OUT of the Staphylococcus of B20 and B19 reached 4485 and 5275, which accounted for 29% and 39% of the total OUT, respectively, suggesting Staphylococcus was the dominant bacteria. OUT of lactic acid bacteria (LAB)of B20 reached 1316, which occupied 9% of the total OUT and indicating LAB was dominant bacteria. Therefore, B19 and B20 were chosen as the raw material.(2) The LAB,Staphylococcus in the two samples was isolated by two media MRS and MSA.The results of isolation indicated 8 strains conformed to LAB,10 strains lined with the characteristic of Staphylococcus.The strain screening was carried on by Gram stain,ability of viscosity production,catalase test,the strain tolerance of simulated sausage fermentation environment, lipolysis capacity, proteolysis and acid production capacity of LAB.The results of these experiments showed G+,no viscosity,catalase positive of bacteria in MSA and negtive of bacteria in MRS. All of the 18 strains isolated could tolerate the temperature of 15℃、pH=5.0、 nitrite of 100mg/kg,while 17 strains survive in 6% NaCl,8 strains could hydrolyze fat,6 strains possessed proteolysis capacity.In summary,the dominant bacteria of Staphylococcus and LAB was S3,S7.The identification results of 16SrDNA showed that S3,L7 respectively was S.epidermidis,L.sakei subsp.(3) The screened strain was used in sausage fermentation with a inoculum of 1%, and the control group was set at the same time(ck). The dominant bacteria were analyzed during fermentation with PCR-DGGE. The results showed that lactic acid bacteria and Staphylococci were dominant bacteria in early fermentation, but Staphylococci decreased and lactic acid bacteria increased later. In sausage inoculated with L7, L7 was dominant bacteria during whole fermentation. The total number of bands significantly reduced from 12 to 4 after fermentation of 14 days. However, the number of bands reduced slowly from 6 to 4 in sausages inoculated with S3. Texture and sensory test showed no significant change in hardness, adhesion of inoculated sausage was significantly higher than the natural fermented sausage, and elasticity of sausage inoculated with Staphylococci was least. Viscosity values of natural fermented sausage and sausage inoculated with S3 has no significant difference, which was lower than sausages fermented with Staphylococci. Chewiness of naturally fermented sausages was best. Sensory evaluation showed that the taste of sausage fermented with lactic acid bacteria was best and the aroma was obvious.The screening strains with sausage fermentation agent.