In the UK cereals products (mostly wheat) are considered to be the main source of iron as they contribute to 39-50% of iron intake. Iron from cereals has low availability due to presence of anti-nutrients and the resistance to digest plants cell wall in the human GI tract. However, they are still considred main dietry source due to the high consumption rate. Aleurone which is the layer found between the starch endosperm and the outer bran is rich in iron. However, aleurone is removed during white flour production leading to iron loss. Therefore, white flour in the UK is fortified with elemental iron which has low solubility. Adding aleurone back to white flour might have a greater bioavailability compared to wholegrain and white with elemental iron flour.
The aim of this project is to investigate the effect of hydrothermal processing and micro-milling on iron release, bioavailability, and phytic acid content which is the main iron bioavailability inhibitor. After in vitro digestion (gastric and intestinal), total iron release from baked and boiled bread made with different types of flour was determined using ICP-OES. Iron uptake by Caco-2 cells was measured using ICP-MS. Phytic acid levels in the bread samples was measured using K-PHYT kit (Megazyme, Inc, Bray, Ireland). All the obtained data was then analyzed applying two-way and three-way ANOVA.
Neither micro-milling nor hydrothermal processing had a significant difference on iron release and uptake. However, iron release from stand and micro-milled wholegrain and white flour enriched with aleurone in gastric phase was significantly increased compared to intestinal phase irrespective of cooking method. Phytic acid content which is found in wheat grain and is abundant in aleurone layer was significantly decreased in cooked wholegrain and aleurone flour compared to raw flour. Together with all the findings of this study, using aleurone as a fortificate for bioavailable iron can be possible. However, a human study which will take place soon can establish whether aleurone has the potential to be used as food fortificant for iron as well as other micronutrients.