White Common Beans (Phaseolus vulgaris) have Higher In vitro Iron Bioavailability than Colored Seed Coat Varieties
M. Mutambuka; S. Hendrich; P.A. Murphy; M.B. Reddy
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A poster presented at the 2012 Global Pulse Researchers Meeting, Kigali, Rwanda- “Transforming Grain-Legume Systems to Enhance Nutrition and Livelihoods”. Abstract: objectives: Common beans are an important source of iron in developing countries, yet there is need and potential to improve their iron bioavailability. This study aimed to model iron bioavailability with respect to key influencing factors; protein, polyphenol, phytate, bean ferritin and iron Content, as well as establishing effects of extrusion cooking. Methodology: A caco2 cell culture model was used to determine iron uptake from in vitro digested bean samples while Response Surface Methodology (RSM) was used for process optimization. Results: Protein Content ranged from 25.7-31.6%; polyphenol, 0.07-0.37 mg/100g; phytate, 0.91-2.17 g/100g; iron, 74.9-119.5 ?g/g; bean ferritin, 206-497 ?g/g, and relative iron bioavailability (based on 100% bioavailability of ferrous sulfate) was 9.1-52.1%. White coated varieties had the highest bioavailability. A fixed effects multiple regression model showed negative effects of polyphenol and positive effects of iron and ferritin interactions. Extruder temperature had greatest effect on extruded flours, increasing polyphenol Content and expansion ratio while reducing peak and final viscosities. Significance: Polyphenol Content is the major determinant of iron bioavailability in common beans, which in turn can be indirectly screened for by seed coat color.