46F-17 |
The effect of in vitro soy bread digestion on isoflavone profile |
Y. C. ZHANG1, K. R. Walsh2, M. L. Failla2, S. J. Schwartz1, and Y. Vodovotz1. (1) Food Science & Technology Department, Ohio State University, 2015 Fyffe Road, Columbus, OH 43210, (2) Department of Human Nutrition & Food Management, Ohio State University, 1787 Neil Avenue, Columbus, OH 43210 Isoflavones present in soy have been associated with a decrease in risks of certain cancers. Baked products, such as bread, made partly with soy ingredients, offer an attractive isoflavone delivery system due to their popularity in the Western diet. An in vitro digestion method serves as a model that emulates in vivo digestive processes thereby providing an indication of components available for intestinal absorption. Our objective was to determine the effects of in vitro digestion on the quantity and the relative stability of three isoflavones daidzein, genistein, and glycitein present in soy bread. Soy bread was homogenized and diluted in saline then subjected to a two-stage in vitro digestion method. This method involves acidification and incubation with pepsin (gastric phase) followed by neutralization and incubation with pancreatin, pancreatic lipase, and bile extract (small intestinal phase). The isolated aqueous micellarized fraction, containing the components which are readily available for absorption, was isolated by centrifugation. Reverse-phase HPLC was used to determine the isoflavone concentration and composition of these samples after acidified acetonitrile extraction. Undigested samples contained 353.8µg of total isoflavones per gram. Similar concentrations of isoflavones were found in the digested aqueous phase. However, the aqueous phase contained lower quantities of isoflavones (80% daidzein, 32% genistein and 46% glycitein) as compared to the amount of isoflavone present in the undigested samples. Aqueous phase micelles were placed on Caco-2 cells to measure the extent of uptake into the intestinal epithelial cells. Reduction of isoflavone concentrations in the aqueous phase and Caco-2 cells after soy bread digestion may lead to alterations in intestinal uptake and bioavailability.
Session 46F, Nutrition
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