Soy germ rich in isoflavones has attracted much attention for health-promoting characteristics. An
effective approach via Monascus aged vinegar soaking was adopted to enhance the aglycone amount.
The profiles and interconversion of soy germ isoflavones via Monascus aged vinegar soaking were investigated,
and the distribution in vinegars were also explored. The aglycones were dramatically increased
by 40.76 times. Concomitantly, b-glycosides and malonylglycosides were significantly decreased. The
proportion of aglycones presented a sharp increase with the endogenous b-glucosidase activity at the initial
4 h incubation. There appeared to be correlations between b-glucosidase activity and the hydrolysis
of conjugated isoflavones. The results demonstrated that the reactions of decarboxylation, de-esterification
and de-glycosylation were involved in the Monascus aged vinegar soaking, supporting synergistic
effects of enzymolysis by endogenous b-glucosidase from soy germ and acid hydrolysis of vinegars.
Soaking by vinegar is a promising pathway for preparing aglycone-rich soy germ.