Role of the Bifidobacteria in Soymilk Fermentation

Soy-based foods are rich in high quality proteins, essential amino acids, minerals, vitamins etc. thus they provide a range of health benefits. In this study, growth and α-galactosidase activity of bifidobacteria (Bifidobacterium lactis Bb-12, B. longum Bb-46, B. bifidum B3.2, B. bifidum B7.1 and B. breve B9.14) were investigated. All tested bifidobacteria strains showed αgalactosidase activity that catalyses hydrolysis of soybean galacto-oligosaccharides. The highest enzyme activity (23.94 U/L) was assayed in the case of B. lactis Bb-12 strain. Soymilk without any additional nutrients was good medium for growth of Bifidobacterium strains. Moreover, 1010 cfu/ml initial cell concentrations resulted in 10 cfu/ml after 8-12 h of incubation in soymilk, and were kept viable up to the end of fermentation (48 h). Due to intensive metabolism, the titratable acidities of the fermented soymilk were in the range of 14 and 29 SH° after 24h of fermentation. Production the lactic and acetic acid were in the range of 23–60 mmol/L and 2.45.6 mmol/L, respectively. Molar ratios of acetate to lactate in all tested strains varied from 0.080.1 that are very promising for further technological development of probiotic fermented soybased food products.