Publication no. C-2004-1028-01R |  VIEW ARTICLE

Changes in Distribution of Isoflavones and beta-Glucosidase Activity During Soy Bread Proofing and Baking.

Yu Chu Zhang (1), Jae Hwan Lee (1), Yael Vodovotz (1), and Steven J. Schwartz (1,2). (1) The Ohio State University, Department of Food Science and Technology, 2015 Fyffe Road, Columbus, OH 43210. (2) Corresponding author. Phone: 614-292-2934. Fax 614-292-4233. E-mail: <zhang.363@osu.edu> Cereal Chem. 81(6):741-745. Accepted May 5, 2004. Copyright 2004 American Association of Cereal Chemists, Inc.

Bread made partially with soy may represent a viable alternative for increasing soy consumption in populations consuming Western diets. The potential health-promoting activity of soy isoflavones may depend on their abundance and chemical form. The objective of this study was to characterize the changes in isoflavone distribution and beta-glucosidase activity during the soy breadmaking process. Soy bread ingredients were combined and mixed to form a dough that was subsequently proofed at 48°C for 1–4 hr and baked at 165°C for 50 min to produce breads. The isoflavone composition and beta-glucosidase activity in bread ingredients, doughs, and breads were monitored. Soy ingredients and wheat flour (not bread yeast) were the major contributors of the beta-glucosidase activity in bread. No degradation of isoflavones was observed during breadmaking but the isoflavone distribution was largely altered. Proofing and baking have important but different roles in changing the isoflavone distribution. Proofing converted isoflavone beta-glucosides to aglycones by highly specific beta-glucosidase activity. Thermal treatment during baking significantly decreased the isoflavone malonylglucosides and increased isoflavone beta-glucosides. Enzyme activity during proofing and the balance between formation and deconjugation of isoflavones during baking determine the isoflavone content and composition in the final product.