Rapid and Reliable Qualitative Methods for Identification of Iron Fortificants in Wheat Flour (P13-015-19)

Abstract

Objectives. Fortification is a common strategy to reduce the prevalence of iron deficiency anemia (IDA). Currently, manufacturers are able to fortify wheat flour with cheaper iron compounds with lower bioavailability, leading to less of an impact on IDA. Therefore, a method is needed for government agencies to monitor the type of iron added to flour. The objective was to develop a quick and simple method to qualitatively determine iron compounds commonly used for fortifying wheat flour. Methods. Unfortified wheat flour was fortified with 40 ppm using these salts: ferric pyrophosphate (FePP), ferrous sulfate (FeSO4), ferrous citrate (FeC), ferrous fumarate (FeF), and sodium iron EDTA (NaFeEDTA), except for electrolytic iron (EFe) where 60 ppm was added. Iron salts were identified based on their magnetic property, solubility in water or acid, and oxidation state. EFe was identified by passing a magnet through the flour. Ferrous and ferric salts were identified using potassium thiocyanate (KSCN) in 3 N hydrochloric acid (HCl) with and without hydrogen peroxide (H2O2). Ferric salts (NaFeDTA and FePP) were identified using Ferrozine and ascorbic acid. Poor solubility of FeF in weak acid with KSCN was used to differentiate it from FeSO4 and FeC. Acidity testing with phenolphthalein and sodium hydroxide (NaOH) further differentiated FeC from FeSO4. Flour samples were tested in triplicates and blinded samples were tested independently. Results. EFe from flour was visible on the magnet. In addition to producing red specks with KSCN, NaFeEDTA in water produced strong color with Ferrozine and ascorbic acid, unlike FePP. Using KSCN and H2O2, FeF did not produce pink color with 0.1 N HCl, unlike FeSO4 and FeC. Acidity testing differentiated FeSO4 and FeC; FeSO4 produced pink color with less NaOH than FeC. Blinded flour samples were independently and correctly identified to confirm the validity of the methods. Conclusions. These quick, inexpensive, and reliable qualitative methods will be useful for agencies to identify the type of iron added to flour to monitor the quality of iron fortification strategies. Funding Sources. Supported by Nutrition International through a grant from Global Affairs Canada. Copyright © American Society for Nutrition 2019.