5. Conclusion
The isoflavone profiles were significantly changed in soy germ
soaked by Yongchun Monascus aged vinegar. The conversion and
degradation of 12 isoflavone forms were determined. The possible
degradation mechanisms varied with the different treatments. It
was obvious that the aglycones were dramatically increased
meanwhile the glycosides significantly reduced via Monascus aged
vinegar approach. 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 present data indicated that the decarboxylation,
de-esterification and de-glycosylation reactions were involved
the interconversion of the isoflavones forms of soy germs during
the soaking by Monascus aged vinegar, reflecting the synergistic
effects of endogenous b-glucosidase activity of soy germ, acid
hydrolysis and formation of the microorganisms. In addition, a
schematic illustration of the interconversion pathway of
isoflavones forms of soy germs via vinegar soaking approach was
proposed. This study opens a promising safe pathway for preparing
aglycone-rich soy germ as functional food ingredients via vinegar
soaking.