Combined isoflavones biotransformation increases the bioactive and antioxidant capacity of soymilk.

This study evaluated the potential of microbial and enzymatic treatments in biotransformed isoflavones in their biologically active forms in soymilk. Seven different cultures of lactic acid bacteria and bifidobacteria associated with the action of immobilized tannase enzyme were screened for isoflavone glycoside biotransformation ability. The biotransformed soymilk samples were characterized regarding isoflavone profile, total phenolic content, and in vitro antioxidant activities. All bacterial strains showed a good growth capacity in soymilk matrix and produced β-glucosidase enzyme, which hydrolyzed isoflavone glycosides into aglycones in soymilk after 24 h of fermentation. The microbial fermentation followed by tannase reaction (FT processes) resulted in the highest increase of bioactive aglycones (10.3- to 13.1-fold for daidzein, 10.4- to 12.3-fold for genistein, and 3.8- to 4.7-fold for glycitein), compared to control soymilk. Further, FT processes enhanced the total phenolic content (53-70%) and antioxidant activity by ORAC (69-102%) and FRAP (49-71%) assays of the soymilk matrix. Therefore, the combination of microbial fermentation and tannase treatment is a promising strategy to obtain a fermented soy product rich in bioactive isoflavones with greater health-promoting potential. KEY POINTS: • Bacterial cultures and tannase enzyme displayed isoflavone deglycosylation activity. • The addition of tannase following the fermentation maximized the isoflavone conversion...
Source: Applied Microbiology and Biotechnology - Category: Microbiology Authors: Tags: Appl Microbiol Biotechnol Source Type: research