To date 12 isoflavones have been reported to be
present in soybean, consisting four chemical forms with
each form having three compounds, as malonyl-bglucoside,
acetyl-b-glucoside and aglycone (Kao &
Chen, 2002; Murphy, Barua, & Hauck, 2002). It has
been established that the bioavailability of isoflavones
can be influenced by their chemical form in foods and
the susceptibility to degradation during heating (Birt et
al., 2001). Barnes, Coward, Kirk, and Sfakianos (1998)
demonstrated that genistein could be formed from
genistin during fermentation, while 600-O-malonylgenistin
could be converted to 600-O-acetylgenistin or genistin
during heating. Thus, the conversion among various
isoflavones during processing of soybean products have
to be investigated.