Novel methods for identification and quantification of iron fortificants in cereal flours
Iron deficiency is the most common nutrient deficiency globally. Fortification of cereal grains is a main strategy used to ameliorate global iron deficiency due to its safety and efficacy. For fortification to be effective, fortification programs must use appropriate iron compounds at appropriate levels. However, existing laboratory methods to identify and quantify fortificants are time consuming and costly. Our objective was to develop a quick and simple method to identify and quantify iron compounds commonly used for flour fortification. Unfortified whole wheat, refined wheat, and yellow corn flours were fortified with 20–60 mg Fe/kg flour using ferric pyrophosphate (FePP), ferrous sulfate (FeSO4), ferrous citrate (FeCit), ferrous fumarate (FeFum), sodium ferric EDTA (NaFeEDTA), and electrolytic iron (EFe). Using potassium thiocyanate (KSCN) with HCl with and without hydrogen peroxide (H2O2), we identified EFe, ferric, and ferrous fortificants. NaFeEDTA, FePP, FeSO4, FeCit, and FeFum were identified based on their solubility in water using ferrozine with and without ascorbic acid (ASC). An alternative method for identification that uses only KSCN as a chromogen was also developed but was inferior to the ferrozine method. Four blinded samples were prepared with randomly selected fortificants (EFe, NaFeEDTA, FePP, FeFum) and all were correctly identified by four personnel. For quantification, those four samples plus an additional FeSO4 sample were tested blindly. The average of each person's reported iron levels for each sample were within 10 mg Fe/kg of actual iron levels 85% of the time. Estimated iron levels from the visual method were not significantly different than iron levels from two standard quantitative methods (p > 0.05) for all the fortificants tested suggesting reliability of simple visual testing. These quick, inexpensive, and reliable methods will be useful for agencies to identify the type and amount of iron added to flour to monitor the quality of iron fortification strategies.