94-4 |
|
Y. C. ZHANG1, J. H. Lee2, S. J. Schwartz1, and Y. Vodovotz1. (1) Dept. of Food Science & Technology, Ohio State Univ., 2015 Fyffe Ct., Columbus, OH 43210-1007, (2) Dept. of Food Science & Technology, Seoul National Univ. of Technology, 172 Gongreung 2- Dong, Nowon-gu, Seoul, 139-743, South Korea The bioavailability and biological activity of soy isoflavones depend greatly on the chemical forms of these compounds. The bread preparation process has shown not to degrade isoflavones in soy bread, however, a significant increase in isoflavone aglycones (165%) occurred throughout the proofing (90% during fermentation) stage. The objective of this study was to optimize proofing conditions (temperature and duration) for endogenous b-glucosidase in soy bread ingredients to yield maximum isoflavone aglycones in the final product. Samples were obtained from soy bread dough before proofing and after proofing at 32oC, 48oC, and room temperature (22oC) for 1, 2, 3, and 4 hours. Isoflavones and b-glucosidase activity in these samples were extracted and quantified. The changes in isoflavone content and composition and their correlations with b-glucosidase activity were studied. Both isoflavone b-glucosides and malonylglucosides in soy bread ingredients were converted to isoflavone aglycones during proofing by b-glucosidase. However, isoflavone b-glucosides was preferred to isoflavone malonylglucosides in this enzyme-substrate reaction. The activity of the b-glucosidases in soy bread ingredients were found to be temperature and time dependent. This study demonstrated how the production of isoflavone aglycones can be manipulated by controlling the time and temperature of proofing with 48oC for one hour being optimal for soy bread.
Session 94, Food Chemistry: Chemical effects of food processing, preservation and formulation
|