In vitro iron availability from iron-fortified whole-grain wheat flour

Iron deficiency is the most common nutritional disorder worldwide. Iron fortification of foods is considered to be the most cost-effective long-term approach to reduce iron deficiency. However, for fortified foods to be effective in reducing iron deficiency, the added iron must be sufficiently bioavailable. In this study, fortification of whole-grain wheat flour with different sources of iron was evaluated in vitro by measuring the amount of dialyzable iron after simulated gastrointestinal digestion of flour baked into chapatis and subsequent intestinal absorption of the released iron using Caco-2 cell layers. The dialyzability of iron from iron-fortified wheat flour was extremely low. Additions of 50 mg/kg iron to the flour in the form of ferrous sulfate, Ferrochel amino acid chelate, ferric amino acid chelate taste free (TF), Lipofer, ferrous lactate, ferrous fumarate, ferric pyrophosphate, carbonyl iron, or electrolytic iron did not significantly increase the amount of in vitro dialyzable iron after simulated gastrointestinal digestion. In contrast, fortification of flour with SunActive Fe or NaFeEDTA resulted in a significant increase in the amount of in vitro dialyzable iron. Relative to iron from ferrous sulfate, iron from SunActive Fe and NaFeEDTA appeared to be 2 and 7 times more available in the in vitro assay, respectively. Caco-2 cell iron absorption from digested chapatis fortified with NaFeEDTA, but not from those fortified with SunActive Fe, was significantly higher than from digested chapatis fortified with ferrous sulfate. On the basis of these results it appears that fortification with NaFeEDTA may result in whole-grain wheat flour that effectively improves the iron status.     

Effect of Micronutrient Fortification on Nutritional and Other Properties of Nixtamal Tortillas

Nixtamalization is the process of steeping dried corn in hot water with calcium hydroxide (lime) with subsequent removal of all or most of the pericarp through washing. The resulting product is called nixtamal. Approximately 60% of corn tortillas in Mexico are produced from nixtamal, with the remainder prepared from nixtamalized corn flour. Nixtamal was fortified with micronutrient premix containing iron, zinc, folic acid, niacin, riboflavin, and thiamin. Premix composition followed a proposed Mexican regulation for corn flour fortification, adjusted for moisture. Effects of premix on masa adhesiveness, hardness, and pH, as well as tortilla sensory properties, stretchability, rollability, and color were measured. Micronutrient levels were tested in the dry corn, nixtamal, masa, and tortillas. There were no significant differences in masa texture or pH, tortilla rollability, or consumer acceptance of tortillas when comparing unfortified control and fortified treatments. Added thiamin was almost entirely degraded during processing. Folic acid and riboflavin decreased 26 and 45%, respectively, through the masa‐tortilla manufacturing process. Niacin showed no significant loss. Despite processing losses, fortification resulted in significant nutrient increases compared with control tortillas. Folic acid increased 974%, riboflavin increased 300%, niacin increased 141%, iron increased 156%, and zinc increased 153% in fortified tortillas.     

Evaluation of the Functionality of Five Different Soybean Proteins in Hot‐Press Wheat Flour Tortillas

Five different soybean protein sources were added to wheat flour to increase the protein content by 15–25%, and the resulting composite flours were optimally processed into hot‐press tortillas in a pilot plant. The rheological properties of composite flours were evaluated with the farinograph, alveograph, and other wheat quality tests. Tortilla‐making qualities of the control and soybean‐fortified flours were evaluated during dough handling, hot pressing, and baking. The resulting tortillas were tested in terms of yield, physical and chemical parameters, sensory properties, color, and objective and subjective texture. The soybean‐fortified tortillas had increased yields because of the higher dough water absorption and enhanced essential amino acid scores. Among the five different soybean proteins, the defatted soybean flour (SBM1) with the lowest fat absorption index and protein dispersibility index (PDI) and the soybean concentrate produced the best fortified tortillas. The protein meals with high PDI and relatively lower water absorption index (SBM3 and SBM4) produced sticky doughs, lower alveograph P/L values, and defective tortillas. All soybean proteins produced higher yields of tortillas with an enhanced protein quality and amount of dietary fiber.     

Inhibition of iron uptake from iron salts and chelates by divalent metal cations in intestinal epithelial cells

Iron chelates, namely, ferrous bisglycinate and ferric EDTA, are promising alternatives to iron salts for food fortification. The objectives of this study were to compare iron uptake from radiolabeled ferrous sulfate, ferrous ascorbate, ferrous bisglycinate, ferric chloride, ferric citrate, and ferric EDTA by Caco-2 cells with different iron status and in the presence of divalent metal cations. Iron-loaded Caco-2 cells, with reduced DMT-1 and elevated HFE mRNA levels, down-regulated uptake from ferrous ascorbate and bisglycinate but not from ferric compounds. Nevertheless, iron uptake from all compounds was markedly inhibited in the presence of 100-fold molar excess of Co2+ and Mn2+ cations, with ferrous compounds showing a greater percent reduction. Our results suggest that ferrous iron is the predominant form of iron taken up by intestinal epithelial cells and the DMT-1 pathway is the major pathway for uptake. Iron uptake from chelates appears to follow the same pathway as uptake from salts.     

Folate Stability in Folic Acid Enriched Corn Masa Flour,Tortillas, and Tortilla Chips over the Expected Shelf Life

Neural tube defects occur at higher rates in Hispanic populations in the United States. Such populations would benefit from folic acid fortification of corn masa flour (CMF). This study evaluated folate stability in fortified CMFs and tortillas and tortilla chips made therefrom. There was no significant loss of folate during the six‐month shelf life of fortified tortilla CMF and tortilla chip CMF. There was a 13% loss (P < 0.05) of folate during tortilla baking and no loss during tortilla chip frying. Both tortillas and tortilla chips showed significant folate losses over the two‐month shelf life for these products, with a 17% loss in fortified tortillas and a 9% loss in tortilla chips. Folate in fortified CMFs, tortillas, and tortilla chips is relatively stable and comparable to the stability of folate in wheat flour and breads.     

Commercial Evaluation of a Continuous Micronutrient Fortification Process for Nixtamal Tortillas

The corn tortilla plays an integral role in the Mexican diet and is an ideal vehicle for micronutrient fortification. Approximately 60% of corn tortillas in Mexico are produced from nixtamal, with the remainder prepared from masa flour. A process for continuous fortification of nixtamal tortillas was evaluated in two commercial mills in Mexico. A commercial powder dosifier was used to add micronutrient premix containing iron, zinc, folic acid, niacin, riboflavin, and thiamin to nixtamal (1 g/kg) as it was milled. After training and preliminary sampling, mills produced fortified tortillas unassisted for four weeks. Masa flow rates over a four‐day period were 10–12 kg/min in both plants. Premix flow from the dosifier showed good stability, with an average coefficient of variation of 1.6%. Initial results indicated consistency in the fortification process, with significantly increased variation during the four‐week production period. Fortified tortillas had significantly higher levels of all nutrients tested. Micronutrient losses were <11% in all cases except folic acid, which showed an 80% loss. Despite processing losses, fortification resulted in a nearly fivefold increase in folic acid compared with control tortillas. The new fortification process is technically viable and was well received by millers.     

Microencapsulated iron for milk fortification

This study was designed to develop a microencapsulated iron that could be used to fortify milk and to determine the sensory properties of milk fortified with microencapsulated iron. Coating material was polyglycerol monostearate (PGMS), and selected core material was ferric ammonium sulfate. The highest efficiency of microencapsulation was 75% with 5:1:30 ratio (w/w/v) as coating to core materials to distilled water. Iron release was 12% when stored at 4 degrees C for 3 days. The TBA value was the lowest when 100 ppm of capsulated iron was added into milk and was significantly lower in capsulated groups compared with that in uncapsulated groups. In an in vitro study, only 3-5% of iron was released in simulated gastric fluid (pH 3, 4, 5, and 6). Comparatively, iron release increased dramatically from 12.3% (pH 5) to 95.7% (pH 8) for 60 min of incubation in simulated intestinal fluid. In a sensory analysis, most aspects except for metallic taste and color were not significantly different between control and capsulated iron fortified milk at 3 days of storage. However, between capsulated and uncapsulated groups, astringency, metallic, color, and overall scores were significantly different. The present study indicated that the use of microencapsulated iron with PGMS is effective for fortifying milk.     

Iron bioavailability of hemoglobin from soy root nodules using a Caco-2 cell culture model

Heme iron has been identified in many plant sources-most commonly in the root nodules of leguminous plants, such as soy. Our objective was to test the effectiveness of soy root nodule (SRN) and purified soy hemoglobin (LHb) in improving iron bioavailability using an in vitro Caco-2 cell model, with ferritin response as the bioavailability index. We assessed bioavailability of iron from LHb (either partially purified (LHbA) or purified (LHbD)) with and without food matrix and compared it with that from bovine hemoglobin (BHb), ferrous sulfate (FeSO4), or SRN. Bioavailability of each treatment was normalized to 100% of the FeSO4 treatment. When iron sources were tested alone (100 ug iron/mL), ferritin synthesis by LHbD and BHb were 19% (P > 0.05) and 113% (P < 0.001) higher than FeSO4, respectively. However, when iron sources were used for fortification of maize tortillas (50 ppm), LHbA and BHb showed similar bioavailability, being 27% (P < 0.05) and 33% (P < 0.05) higher than FeSO4. Heat treatment had no effect on heme iron but had a significant reduction on FeSO4 bioavailability. Adding heme (LHbA) iron with nonheme (FeSO4) had no enhancement on nonheme iron absorption. Our data suggest that heme iron from plant sources may be a novel value-added product that can provide highly bioavailable iron as a food fortificant.     

Fermentation and lactic acid addition enhance iron bioavailability of maize

Maize is one of the most important cereal crops for human consumption, yet it is of concern due to its low iron bioavailability. The objective of this study was to determine the effects of processing on iron bioavailability in common maize products and elucidate better processing techniques for enhancing iron bioavailability. Maize products were processed to represent different processing techniques: heating (porridge), fermentation (ogi), nixtamalization (tortillas), and decortication (arepas). Iron and phytate contents were evaluated. Iron bioavailability was assessed using the Caco-2 cell model. Phytate content of maize products was significantly reduced by decortication (25.6%, p = 0.003) and nixtamalization (15%, p = 0.03), and iron content was reduced by decortication (29.1%, p = 0.002). The relative bioavailability (RBA, compared to 100% bioavailability of porridge with FeSO4) of ogi was significantly higher than that of other products when fortified with FeSO4 (p < 0.001) or reduced iron (p < 0.001). Addition of lactic acid (6 mg/g of maize) significantly increased iron solubility and increased bioavailability by about 2-fold (p < 0.01), especially in tortillas. The consumer panel results showed that lactic acid addition does not significantly affect the organoleptic characteristics of tortillas and arepas (p = 0.166 and 0.831, respectively). The results suggest that fermentation, or the addition of small amounts of lactic acid to unfermented maize products, may significantly improve iron bioavailability. Lactic acid addition may be more feasible than the addition of highly bioavailable but expensive fortificants. This approach may be a novel means to increase the iron bioavailability of maize products to reduce the incidence of iron deficiency anemia.     

Mineral dialyzability in milk and fermented dairy products fortified with FeNaEDTA

Iron, zinc, and calcium dialyzability and ascorbic acid (AA) concentrations were evaluated in milk and yogurt fortified with FeNaEDTA (FE) or ferrous sulfate (FS) as a control, with or without AA addition. The values obtained for FE iron dialyzability in milk were much higher than those obtained for FS. The addition of AA to milk improved Fe dialyzability when using FS and slightly decreased Fe dialyzability in the FE-fortified nonfermented samples. Milk fermentation increased iron availability from both iron sources. Zinc and calcium dialyzability in products containing any of the two iron sources was increased in fermented milks. EDTA improved Zn dialyzability from intrinsic zinc in every manufactured dairy product. Whereas for milks fortified with FS and stored at 4 degrees C for 24 h, the AA content remained close to the original concentration, a higher AA degradation was observed when milks were fortified with FE.     

The influence of vegetation and soil type on the speciation of iron in soil water

Soluble organic matter derived from exotic Pinus species has been shown to form stronger complexes with iron (Fe) than that derived from most native Australian species. It has also been proposed that the establishment of exotic Pinus plantations in coastal southeast Queensland may have enhanced the solubility of Fe in soils by increasing the amount of organically complexed Fe, but this remains inconclusive. In this study we test whether the concentration and speciation of Fe in soil water from Pinus plantations differs significantly from soil water from native vegetation areas. Both Fe redox speciation and the interaction between Fe and dissolved organic matter (DOM) were considered; Fe – DOM interaction was assessed using the Stockholm Humic Model. Iron concentrations (mainly Fe²⁺) were greatest in the soil waters with the greatest DOM content collected from sandy podosols (Podzols), where they are largely controlled by redox potential. Iron concentrations were small in soil waters from clay and iron oxide‐rich soils, in spite of similar redox potentials. This condition is related to stronger sorption on to the reactive clay and iron oxide mineral surfaces in these soils, which reduces the amount of DOM available for electron shuttling and microbial metabolism, restricting reductive dissolution of Fe. Vegetation type had no significant influence on the concentration and speciation of iron in soil waters, although DOM from Pinus sites had greater acidic functional group site densities than DOM from native vegetation sites. This is because Fe is mainly in the ferrous form, even in samples from the relatively well‐drained podosols. However, modelling suggests that Pinus DOM can significantly increase the amount of truly dissolved ferric iron remaining in solution in oxic conditions. Therefore, the input of ferrous iron together with Pinus DOM to surface waters may reduce precipitation of hydrous ferric oxides (ferrihydrite) and increase the flux of dissolved Fe out of the catchment. Such inputs of iron are most probably derived from podosols planted with Pinus.     

Effect of High‐Molecular‐Weight Glutenin Subunit Allelic Composition on Wheat Flour Tortilla Quality

Wheat cultivars possessing quality attributes needed to produce optimum quality tortillas have not been identified. This study investigated the effect of variations in high‐molecular‐weight glutenin subunits encoded at the Glu‐1 loci (Glu‐A1, Glu‐B1, and Glu‐D1) on dough properties and tortilla quality. Flour protein profiles, dough texture, and tortilla physical quality attributes were evaluated. Deletion at Glu‐D1 resulted in reduced insoluble polymeric protein content of flour, reduced dough compression force, and large dough extensibility. These properties produced very large tortillas (181 mm diameter) compared with a control made with commercial tortilla wheat flour (161 mm). Presence of a 7 + 9 allelic pair at Glu‐B1 increased dough strength (largest compression force, reduced extensibility, and small‐diameter tortillas). Deletion at Glu‐A1 produced large tortillas (173 mm) but with unacceptable flexibility during storage (score <3.0 at day 16). In general, presence of 2* at Glu‐A1, in combination with 5 + 10 at Glu‐D1, produced small‐diameter tortillas that required large force to rupture (tough texture). Presence of 2 + 12 alleles instead of 5 + 10 at Glu‐D1 produced tortillas with a good compromise between diameter (>165 mm) and flexibility during storage (>3.0 at day 16). These allele combinations, along with deletion at Glu‐D1, show promise for tortilla wheat development.     

Impact of Iron Source and Concentration on Rice Flavor Using a Simulated Rice Kernel Micronutrient Delivery System

An extruded grain designed to look like a rice kernel fortified with one of two sources of iron (elemental iron and ferrous sulfate), with and without multiple fortificant (zinc, thiamin, and folic acid), was mixed with milled Calrose rice at low (1:200), medium (1:100), and high (1:50) concentrations. The intensities of water‐like, sour taste, hay‐like musty, and alfalfa/grassy/green bean flavors were enhanced by the addition of ferrous sulfate (FeSO₄) or FeSO₄ plus multiple fortificants. Astringent mouthfeel was likewise affected by addition of FeSO₄ or FeSO₄ plus multiple fortificants. Overall, the elemental iron with multiple fortificants least affected the oxidation of the extruded kernals. Lipid oxidation products in stored fortificant increased the first two to three months and concentrations were higher in samples with FeSO₄ as the iron source.     

Phenolic Compounds and Antioxidant Activity of Extruded Nixtamalized Corn Flour and Tortillas Enriched with Sorghum Bran

Sorghum bran (SB) is a good source of phenolic compounds with high antioxidant capacity that increases the antioxidant activity (AOX) of tortillas prepared with extruded nixtamalized corn flour. The objective of this research was to study the effects of bran addition (0, 5, or 10%) before (ENBESB) or after (ENAFSB) extrusion, in the features and composition of baked tortillas in terms of total phenolic compounds (TPC), AOX, color (L , a , b, hue, chroma, and E value), and tortilla firmness. It was possible to retain more than 81.8 and 89.9% of TPC and AOX, respectively, in ENBESB‐10% flour. Tortillas prepared with ENAFSB‐10% flour retained more than 92 and 76% of TPC and AOX, respectively, compared with ENBESB. However, tortillas elaborated with ENAFSB flour showed a higher firmness and lower flexibility than counterparts produced from ENBESB. The use of extrusion to produce nixtamalized corn flours and the strategy of adding the SB to the corn meal before extrusion were essential to retain TPC and AOX and, additionally, to enhance texture of tortillas.     

Iron fertilization of kentucky bluegrass

Abstract

Iron applications are sometimes used to enhance the color (darker green) of turfgrass stands even when iron is not deficient. A study was conducted to determine the feasibility of replacing a portion of the total yearly N applied to Kentucky bluegrass (Poa pratensis L.) with iron. Turfgrass response to iron chelate (Sequestrene 330) applications at 2.2 kg Fe ha^‐1 in combination with three liquid‐applied N sources (urea, Formolene, and FLUF) at 25 kg N ha^‐1 was compared to turf response from applications of the N sources at 49 kg N ha^‐l. Iron was substituted for part of the N in either the first and second, second and third, or third application in a four application per year program. The study was conducted for three years, and the fertilized turf was rated for color weekly during the growing season. Depending on N source and frequency of Fe application, turf treated with N received higher color ratings compared to turf receiving Fe + N on 13 (Formolene + Fe in third application) to 36% (Fluf + Fe in first and second application) of the rating dates. Turf color was judged acceptable on 78 to 85% of the rating dates for turf treated with N and 62 to 85% of the rating dates for turf treated with Fe + N. The results indicate that it is feasible to substitute iron for a portion of the N in a urea or Formolene fertilization program but that caution should be used when replacing N from FLUF with iron.     

Effects of Fortification and Enrichment of Maize Tortillas on Growth and Brain Development of Rats Throughout Two Generations

The growth and brain development of laboratory rats fed typical indigenous tortilla‐based diets were determined throughout two generations. The experiment compared three different types of tortilla‐based diets: regular tortillas produced from dry masa flour (RDMF), tortillas obtained from fresh masa (FM), and tortillas produced from dry masa flour fortified with 6% defatted soybean and enriched with vitamins B₁, B₂, niacin, and folic acid and microminerals iron and zinc (FEDMF). Female rats were mated 58 days postweaning with males belonging to the same treatment with the objective of obtaining second generation pups that were further subjected to regular lactation and 28 day postweaned growth. A comparison between growth of first and second generation rats was determined. In addition, representative animals of each physiological stage were first exsanguineted for hematocrit determination and then slaughtered with the aim of obtaining femur and brain tissues. Cerebral DNA and number of neurons were determined in each of the brains sampled. Growth of rats fed FEDMF was significantly higher (P < 0.05) in both generations than counterparts fed RDMF or FM. The difference among treatments was more evident in second generation rats. Pregnancy rate, number of newborns per litter, litter weight, and pup's survival rate was higher for the control and FEDMF treatments. Femur growth was also higher (P < 0.05) for first‐generation male adult rats fed control and FEDMF. The concentration and total content of cerebral DNA and number of neurons in males and females belonging to the first generation was similar. However, for second generation rats, these values were lower for animals fed regular tortilla diets. This data clearly demonstrates that the negative effects of malnutrition on brain development of pups occurred during gestation and lactation.     

Sorghum genotype differences to leaf “red‐speckling”; induced by phosphorus 1

Sorghum [Sorghum bicolor (L.) Moench] plants grown in nutrient solutions, sand, and soil under greenhouse or growth chamber conditions developed a lower leaf “red‐speckling”; which was induced by phosphorus (P). As P in solution increased, the intensity of the “red‐speckling”; increased. Although the severity of “red‐speckling”; was not directly related to leaf P concentration, leaves with more severe symptoms had higher P concentrations. KS35, ‘Martin’, and ‘Plainsman’ developed severe symptoms, CK60‐Korgi, SC369–3‐1JB, and TX415 developed intermediate symptoms, and NB9040 developed no symptoms when grown at relatively low levels of P (10 to 20 umol per plant). Organic sources of P induced more severe “red‐speckling”; than inorganic sources. The severity of “red‐speckling”; induced by P compounds followed the sequence of gyceryl > ethyl ammonium = phenyl > potassium dihydrogen > calcium meta > calcium dibasic > calcium tribasic > ferric > calcium pyro = ferrous = aluminum phosphates. “Red‐speckling”; on young sorghum leaves may be caused by excess P. This excess or toxic P “red‐speckling”; occurred at P levels lower than had normally been considered or expected.     

Rheological and Sensory Evaluation of Wheat Flour Tortillas During Storage

Texture of wheat flour tortillas over 15 days at room temperature was evaluated using an expert sensory panel, consumer panels, subjective rollability test, large deformation rheological methods (i.e., bending, extensibility [1‐D and 2‐D], and puncture tests), and stress relaxation method. Most of the changes in texture occurred during the initial 8 days of storage, while texture of tortillas changed slowly thereafter. Differences in texture between fresh and 1‐day‐old tortillas were detected by many objective rheological methods but not by either sensory panel. The expert sensory panel observed a rapid decrease in tortilla extensibility and an increase in staleness between 1 and 8 days of storage and smaller changes in sensory scores after 8 days of storage. Most objective rheological parameters changed rapidly between 0 and 5 days, and slowly after 5 days of storage. Significant correlations and factor analysis reveal that changes occurring in flour tortillas during staling are estimated better by subjective rollability, sensory evaluation (expert and consumer panels), and 2‐dimensional extensibility test than by other methods. Hence, some rheological methods are useful to estimate sensory properties of flour tortillas.     

Stability of Native Folate and Added Folic Acid in Micronutrient‐Fortified Corn Masa and Tortillas

Degradation of added folic acid and native folates in micronutrient‐fortified corn masa and tortillas was evaluated using masa prepared from either nixtamalized corn flour or fresh nixtamal. Variations in masa pH, masa holding time at an elevated temperature, and iron source failed to show significant differences in folate loss in corn flour masa prepared in the laboratory. Masa was subsequently prepared from fresh nixtamal in a commercial mill in Mexico, and fortified with one of two different micronutrient premixes containing iron, zinc, B‐vitamins, and either unencapsulated or lipid‐encapsulated folic acid. Folate loss in commercial masa increased significantly with prebake masa holding time for both premixes. Unencapsulated folic acid showed a 73% loss after 4 hr of holding, compared to 60% loss for encapsulated. The difference was statistically significant, indicating a protective effect from the lipid coating. No significant differences in folate levels were found between prebake masa and baked tortillas. Holding baked tortillas for up to 12 hr also had no effect on folate levels. Native folate showed no significant losses throughout the process. Results from the commercial tortilla mill indicate that most of the loss in added folic acid occurs during prebake holding of masa, possibly from microbial degradation.     

The role of iron and the factors affecting off-color development of polyphenols

Iron deficiency affects over two billion people worldwide (Lotfi, M.; Venkatesh Mannar, M. G.; Merx, R. J.; Naber-van den Heuvel, P. Micronutrient Fortification of Foods: Current Practices, Research,and Opportunities; Micronutrient Initiative: Ottawa, Ontario, Canada, 1996). However, fortifying foods with highly bioavailable iron is technically challenging because of off-color and off-flavor development, catalytic degradation of vitamins, and oxidation of lipids. The role of highly bioavailable iron in the off-color development of foods and beverages is not well-understood. The goal of this research was to examine the interaction of iron with simple phenolics and polyphenols. Factors that may affect off-color development, such as pH, oxygen, temperature, and reducing and chelating agents, were evaluated as a model for food products. Our results demonstrated that the iron that reacts with the simple phenolic, catechol, to develop off-color must be in the oxidized state, and the iron is reduced in the presence of catechol. Because this is an oxidation/reduction reaction, the redox potential of all of the components is critical to the color development. Ferrous iron sources with low redox potentials and ferric iron sources with high redox potentials caused off-color development with catechol. Only polyphenols that contain ortho-hydroxyl groups cause off-color development with iron. All of the factors tested affect off-color development and redox potential of the system. Low pH, low oxygen, high temperature, and the presence of reducing and chelating agents inhibited off-color development. To confirm the model, foods that contained these polyphenols were evaluated for off-color development when iron was added. The foods tested reacted similarly to the models of polyphenols with iron. Off-color development was caused by oxidation-reduction interactions between ferric iron and polyphenols that contained ortho-dihydroxyl groups. Ferrous iron needed to be oxidized to participate in off-color development. In addition, methods identified in the models to prevent off-color development were effective in most of the food products examined. Using the ferrous form of iron and maintaining it in its reduced form by lowering pH, removing oxygen, and including reducing agents, it was possible to fortify foods with highly bioavailable iron.