44E-4

Effectiveness of diglycosidase for the conversion of isoflavone glycosides to aglycones

L. XIE1, N. S. Hettiarachchy1, K. Tsuruhami2, and S. Koikeda2. (1) Department of Food Science, University of Arkansas, Fayetteville, AR 72704, (2) Amano Enzyme Inc., 4-179-35, Sue-cho, Kakamigahara, Gifu, 509-0108, Japan

Cancer is the second leading cause of death in the United States, but early in the twenty-first century cancer is projected to surpass heart disease as the number one killer. There have been concerns about the bioavilability of isoflavones. In soybeans, most isoflavones exist as beta glycosides. However, it is recognized that readily bio-avilable isoflavones are present as aglycones rather than as glycoside.

The objective of this study is to evaluate the effectiveness of Amano Enzyme Inc. diglycosidase in converting acetyl and malonyl glucosides to aglycones in commercial soy meal and soylife.

Commercial 5 g soy meal (SM) or 5 g soylife (SL) were used for each treatment. 5 g SM or SL was dispersed in 30 ml deionized water. Three/ five /seven units of diglycosidase enzyme per g SM or SL were added to SM or SL dispersion. The SL & SM dispersions were adjusted to pH 4.0/pH4.5/pH5.0, respectively and stirred for 5 hours at 50° C/55° C. After 5 hours incubation, SM and SL solutions were extracted with 80% methanol buffer for 1 hour. This extract was separated and quantify by HPLC for the isoflavone contents (genistin, daidzin, glycitin and their corresponding aglycones).

These results demonstrated that 99.56% (SM) and 98.94% (SL) of genistin glycoside, 89.84% (SM) and 99.66% (SL) of glycitin glycoside, 98.69% (SM) and 98.2% (SL) of daidzin glycoside were converted to their corresponding aglycones at pH5.0, 50° C, 5 hours incubation. Almost all isoflavone glycosides were quantitatively converted to their corresponding aglycones. Diglycosidase can be very effective in the conversion of glycosides to aglycones (bioactive compounds) in various isoflavone enriched soy food products.

Session 44E, Nutraceuticals & Functional Foods
8:30 AM - 12:00 PM, 2001-06-25 Room Hall D

2001 IFT Annual Meeting - New Orleans, Louisiana