Table 1 presents the isoflavone profiles of soy germ after
Monascus aged vinegar soaking, water soaking and cooking as the
control. In the raw soy germs, the isoflavones consisted of 63.34%
malonylglycosides, 31.79 % b-glycosides, 3.69% acetylglycosides
and 1.18% aglycones. In general, isoflavones are not destroyed by
soaking in water, acid hydrolytic, fermentation and heat, but rather
are subjected to the interconversion between the different forms.
The changes of isoflavone profiles in soy germ were investigated
after Monascus aged vinegar soaking for 72 h at 25 C, and the
related results were listed in Table 1. The data indicated that
malonylglycosides in soy germ could readily be converted to their
respective acetylglycosides and nonconjugated b-glycosides
through the decarboxylation and deesterification, respectively.
Concomitantly, b-glycosides forms were transformed to aglycone
forms by endogenous b-glucosidase (Table 1). The deesterification
reaction of malonyl glycosides was faster than the decarboxylation
reaction under the environment, that is, the conversion from malonyl
glycosides to glycosides was faster than to acetylglycosides.
The Monascus aged vinegar soaking resulted in aglycone-rich soy
germ, and aglycones were further increased from 36.8% to 51.34%
by the soaking with recovered Monascus aged vinegar (Table 1