Development and optimization of iron- and zinc-containing nanostructured powders fornutritional applications

Abstract

Reducing the size of low-solubility iron (Fe)-containing compounds to nanoscale has thepotential to improve their bioavailability. Because Fe and zinc (Zn) deficiencies oftencoexist in populations, combined Fe/Zn-containing nanostructured compoundsmay be useful for nutritional applications. Such compounds are developed hereand their solubility in dilute acid, a reliable indicator of iron bioavailability inhumans, and sensory qualities in sensitive food matrices are investigated.Phosphates and oxides of Fe and atomically mixed Fe/Zn-containing (primarilyZnFe2O4) nanostructured powders were produced by flame spray pyrolysis (FSP). Chemicalcomposition and surface area were systematically controlled by varying precursorconcentration and feed rate during powder synthesis to increase solubility to the level offerrous sulfate at maximum Fe and Zn content. Solubility of the nanostructured compoundswas dependent on their particle size and crystallinity. The new nanostructuredpowders produced minimal color changes when added to dairy products containingchocolate or fruit compared to the changes produced when ferrous sulfate orferrous fumarate were added to these foods. Flame-made Fe- and Fe/Zn-containingnanostructured powders have solubilities comparable to ferrous and Zn sulfatebut may produce fewer color changes when added to difficult-to-fortify foods.Thus, these powders are promising for food fortification and other nutritionalapplications.