Fermentation characteristics of six probiotic strains in soymilk

Fermented soymilk was produced with the single culture of the six probiotic strains, including Lactobacillus casei Zhang, Bifidobacterium animalis ssp. lactis V9, Lactobacillus acidophilus NCFM, Lactobacillus rhamnosus GG, Bifidobacterium animalis Bb12, and Lactobacillus casei Shirota, and their fermentation characteristics were evaluated. The free amino nitrogen of soymilk fermented with the four probiotic strains, L. casei Zhang, B. animalis V9, L. acidophilus NCFM and L. rhamnosus GG, increased greatly. Significant increases in viable counts were observed among the six probiotic strains. All the fermented soymilk had a viable count above 8.69 log CFU/g at the end of fermentation, especially the four probiotic strains of L. casei Zhang, L. acidophilus NCFM, B. animalis Bb12, and L. casei Shirota, which were all over 9.00 log CFU/g. The content of glucose and fructose decreased for all the six probiotic strains after the fermentation, but along with the reduction in the content of stachyose and raffinose only for B. animalis V9, L. rhamnosus GG, and B. animalis Bb12. Our results indicated that the six probiotic strains can grow well and increase the contents of bioactive substances in soymilk, including gamma-aminobutyric acid, vitamin B6, and total isoflavone aglycone, and deserves further research on utilization as potential starters for soymilk.