Biotransformation of isoflavones by bifidobacteria in fermented soymilk supplemented with D-glucose and L-cysteine

Abstract

Soymilk prepared using soy-protein isolate supplemented with D-glucose and L-cysteine was fermented with 4 strains of Bifidobacterium. Enumeration of bifidobacteria and quantification of isoflavones using HPLC were performed at 0, 12, 24, 36 and 48 h of incubation. Supplementation did not significantly enhance (p > 0.05) the growth of bifidobacteria between 0 and 12 h, but did after 12 h. The increase in concentration of isoflavone aglycones and equol was significantly lower (p < 0.05) in supplemented soymilk after 24 h when compared to plain soymilk. Supplementation increased the concentration of aglycones by 0.796 mg/100 mL in soymilk fermented with B. animalis between 12 and 24 h, and the population by 1.27 log10 CFU/mL (p < 0.05).