Isolation,identification And Fermentation Characteristics Of Lactic Acid Bacteria In Vinegar

Lactic acid bacteria are an important resource for probiotics secreening,which have the functions of regulating intestinal flora,enhancing immunity and reducing blood lipid.With the further research on the solid-state fermentation process of vinegar,it is found that lactic acid bacteria play an important role in the whole process of vinegar brewing and there are rich bacterial species diversity in vinegar.Therefore,lactic acid bacteria were isolated and identified from vinegar samples in Zhangjiajie,Hunan.Then,the isolated dominant lactic acid bacteria were screened for acid resistance,growth characteristics and coagulation properties.The screened excellent strain was applied to the milk and plants materials,for evaluating their fermentation characteristics.The main results are as follows:(1)The viable count of 6 vinegar samples in Zhangjiajie,Hunan,ranged from 1.30×10~2～2.66×10~3CFU/m L.A total of 26 strains were isolated and identified as 6 genera and 12species by 16S r RNA gene sequencing and phylogenetic relationship analysis.Lactococcus lactis was the dominant strain,accounting for 23.1%of the total number of isolates.A strain of Lactococcus lactis IMAU95221 was obtained with excellent coagulating properties.(2)The fermentation results showed that it took about 9h to get the fermentation end(p H=4.5)for fermented milk and fermented soymilk when Lactococcus lactis IMAU95221compounded with the basic starter.For fermentation,the viable count and titratable acidity of Lactococcus lactis IMAU95221 in fermented milk were significantly higher than those in fermented soymilk(P<0.05),while results of the viscosity and water holding capacity were opposite.At the end of fermentation,the fermented milk compound group reached the end of fermentation firstly,and each index was higher than other groups.(3)The results of storage showed that the hardness,consistency and cohesiveness of the two groups of fermented milk were higher than those of the control group,showing excellent storage stability.After the end of storage,the number of viable bacteria in the fermented milk of the compound group was higher,which was 9.7×10~9CFU/m L.The results of electronic tongue detection showed that the taste of fermented milk was moderately sour and sweet,and the taste was stable during storage.The sample state was more delicate,the wire drawing was good,and the sensory evaluation score was the highest.The results of sensory evaluation showed that Lactococcus lactis IMAU95221 had better sensory characteristics in milk fermentation.In summary,the excellent lactic acid bacteria Lactococcus lactis IMAU95221 was obtained from vinegar samples for fermentation of milk and soymilk respectively.The results showed that the strain had more advantages in milk fermentation.This study provided guiding significance for the utilization of the excellent strain Lactococcus lactis IMAU95221 in vinegar and the development of new fermented milk.It provided theoretical data support for the development of the strain as a probiotic starter.