Bioconversion of isoflavone glycosides to aglycones, mineral bioavailability and vitamin B complex in fermented soymilk by probiotic bacteria and yeast

Aim: To study the role of b-glucosidase producing probiotic bacteria and yeast
in the biotransformation of isoflavone glycosides to aglycones, mineral
bioavailability and vitamin B complex in fermented soymilk.
Methods and Results: Five isolates of probiotic lactic acid bacteria (LAB),
Lactobacillus acidophilus B4496, Lactobacillus bulgaricus CFR2028, Lactobacillus
casei B1922, Lactobacillus plantarum B4495 and Lactobacillus fermentum B4655
with yeast Saccharomyces boulardii were used to ferment soymilk to obtain the
bioactive isoflavones, genistein and daidzein. High-performance liquid
chromatography was used to analyse the concentration of isoflavones. Bioactive
aglycones genistein and daidzein after 24 and 48 h of fermentation ranged from
97Æ49 to 98Æ49% and 62Æ71 to 92Æ31% respectively with different combinations
of LAB with yeast. Increase in bioavailability of minerals and vitamin B complex
were also observed in fermented soymilk.
Conclusions: LAB in combination with yeast S. boulardii has great potential for
the enrichment of bioactive isoflavones, enhancing the viability of LAB strains,
decreasing the antinutrient phytic acid and increasing the mineral
bioavailability in soymilk fermentation.
Significance and Impact of the Study: Fermentation of soymilk with probiotic
organisms improves the bioavailability of isoflavones, assists in digestion of
protein, provides more soluble calcium, enhances intestinal health and supports
immune system. Increased isoflavone aglycone content in fermented soymilk
improves the biological functionality of soymilk.