Production of β-Glucosidase and Hydrolysis of Isoflavone Phytoestrogens by Lactobacillus acidophilus, Bifidobacterium lactis, and Lactobacillus casei in Soymilk

The study determined β-glucosidase activity of commercial probiotic organisms for hydrolysis of isoflavone to aglycones in fermenting soymilk. Soymilkmade with soy protein isolate (SPI)was fermented with Lactobacillus acidophilus LAFTI� L10, Bifidobacterium lactis LAFTI� B94, and Lactobacillus casei LAFTI� L26 at 37 ◦C for 48 h and the fermented soymilkwas stored for 28 d at 4 ◦C. β-Glucosidase activity of organisms was determined using ρ-nitrophenyl β-D-glucopyranoside as a substrate and the hydrolysis of isoflavone glycosides to aglycones by these organisms was carried out. The highest level of growth occurred at 12 h for L. casei L26, 24 h for B. lactis B94, and 36 h for L. acidophilus L10 during fermentation in soymilk. Survival after storage at 4 ◦C for 28 d was 20%, 15%, and 11% greater (P < 0.05) than initial cell counts, respectively. All the bacteria produced β-glucosidase, which hydrolyzed isoflavone β-glycosides to isoflavone aglycones. The decrease in the concentration of β-glycosides and the increase in the concentration of aglyconeswere significant (P