**4. Conclusions**

Using the DGAS enzymatic process, IFAs were modified to generate various forms of isoflavone glucosides with different polarities. In addition, transglycosylated IFAs had α-glycosidic bonds in the isoflavone backbone because of the enzymatic properties of DGAS. Different conversion yields of transglycosylation products were achieved for different reaction conditions. The most efficient transglycosylation resulted from a low acceptor concentration (IFAs), donor-high concentration (sucrose), and high DGAS enzyme activity. Applying the reaction conditions used in this study, IFA-rich extracts from SBE were obtained by an environmentally friendly process using CE. The treatment of IFA standards and IFA-rich extract with DGAS produced higher amounts of isoflavone polyglucosides than isoflavone monoglucosides. Taken together, the results of this study suggest that DGAS-treated transglycosylation changes physicochemical properties such as the bioactivity, solubility and stability of isoflavones in soybeans and produces soybean-based functional ingredients rich in transglycosylated IFA.

**Author Contributions:** Conceptualization, Y.S.J. and D.-H.S.; methodology, Y.-J.K., D.J., and M.-S.K.; validation, Y.S.J.; formal analysis, T.G.N., and C.-S.R.; data curation, C.-S.R.; investigation, D.J., M.-S.K., D.-H.S., and T.G.N.; writing—original draft preparation, Y.S.J., and Y.-J.K.; writing—review and editing, A.T.K., C.-S.P., and D.-O.K.; supervision, D.-O.K.; project administration, D.-O.K. All authors have read and agreed to the published version of the manuscript.

**Funding:** This research was funded by the Rural Development Administration Agenda of Korea, grant number "PJ01251204".

**Conflicts of Interest:** The authors declare no conflict of interest.
