Ferric Orthophosphate Research Articles

Oxygen control and improved denitrification efficiency by dosing ferrous ions in the anoxic reactor

Small concentrations of dissolved oxygen (DO) in the range 0.2–0.4 mg L−1 normally are present in biological pre-denitrification reactors. This situation causes adverse effects on denitrification rate and, consequently, on the process efficiency. The results presented show the possibility to control the DO in the anoxic reactor by dosing ferrous Fe(II) ions. The experiments were carried out on both batch samples and a pilot plant and proved that oxidation of Fe(II) to Fe(III) is very efficient in the DO control. Moreover, Fe(III) reacts with phosphorus which precipitates as ferric orthophosphate. A dose of 6 mgFe2+ L−1 decreased the mean DO concentration from 0.45 to 0.28 mg L−1; as a consequence, the denitrification efficiency (ηDEN) increased from about 65–77%. ηDEN reached up to 89% with 9 mgFe2+ L−1 (50% over the stoichiometric for phosphorus removal) thanks to an average DO concentration of 0.08 mgO2 L−1 in the denitrification stage. The results also highlighted the strong influence of DO (and consequently the dosage of Fe2+) on the specific denitrification rate suggesting to maintain DO concentration in the pre-denitrification reactors lower than 0.2 mg L−1 in order to achieve high operation efficiencies.

Effect of Iron Source on Color and Appearance of Micronutrient‐Fortified Corn Flour Tortillas

ABSTRACTIron deficiency anemia is a widespread occurrence. Consequently, iron is commonly added in cereal fortification programs. However, many iron sources cause undesirable sensory changes, especially color changes, in the food being fortified. This study evaluated the effect of different iron sources on CIE L*a*b* color values and sensory color perception in fortified corn tortillas. Corn masa flour was fortified with micronutrient premix containing vitamins, zinc, and one of eight iron compounds. Iron sources included ferrous fumarate (F), ferrous sulfate (S), ferric orthophosphate (OP), ferrous lactate (L), ferrous gluconate (G), ferric pyrophosphate (PP), sodium iron (III)‐EDTA, and A‐131 electrolytic iron (E), with addition levels adjusted based on bioavailability. Control (Ct) samples were prepared with all micronutrients except iron. All iron‐fortified tortillas had lower L* values and were significantly darker than control tortillas. Based on instrumental color values and Mexican regulatory recommendations, five treatments were selected for further testing. A difference‐from‐control sensory test was conducted comparing PP, E, OP, F, and S with Ct tortillas. Sensory rankings were C t > E = PP > OP > F > S. A‐131 electrolytic iron is recommended for fortification of corn tortillas due to minimal effect on color and significantly lower cost than other iron sources evaluated.

Physicochemical properties and bioavailability of five sources of ferric orthophosphate in ready‐to‐eat cereal

The light color and oxidative stability of ferric orthophosphate (FeOP4) make it an attractive iron fortificant. However, FeOP4 has had limited use in cereal due its variable source-to-source bioavailability. An understanding of the mechanisms underlying this variability may facilitate production of a FeOP4 source with consistent bioavailability. Five FeOP4 sources were processed into ready-to-eat cereal, added to diets, and fed to anemic rats for 2-wks. The relative bioavailability values (RBVs) ranged from 51 – 99% (see table). Sources 1–3 were standard Fe2So4, RBV=100, and 2 controls (not presented). Particle surface area (SA) and mean particle size (MPS) influence solubility. SA, PS, and the PS distribution may partially explain the variable RBVs (see table). Preferential moisture uptake by the amorphous content of the samples, measured by Dynamic Vapor Sorption, provides further explanation (see table). In summary, the variable RBV of FeOP4 appears to be influenced by a combination of SA, PS, and amorphous content. Funded by the Kellogg Company. Ferric Orthophosphate Characteristics

Iron Bioavailability from Fortified Fluid Milk and Petit Suisse Cheese Determined by the Prophylactic–Preventive Method

In this research, we measure the iron bioavailability of micronized ferric orthophosphate when it is used to fortify low-fat fluid milk enriched with calcium and petit suisse cheese using the prophylactic-preventive method in rats. Four groups of male weaned rats received a basal diet (control diet; 6.5 ppm Fe), a reference standard diet (SO4Fe; 18.2 ppm Fe), a basal diet using iron-fortified fluid milk as the iron source (milk diet; Fe ppm 17.9), and a basal diet using iron-fortified petit suisse cheese as the iron source (cheese diet; 18.0 ppm Fe) for 22 d. The iron bioavailability of the different sources was calculated as the ratio between the mass of iron incorporated into hemoglobin during the experiment and the total iron intake per animal. The relative biological values with regard to the reference standard (RBV%) were 61% and 69% for the milk and cheese diet, respectively. These results show that according to this method, the iron bioavailability in both fortified foods can be considered as medium bioavailability rates.

Bioavailability of Petit-Suisse cheese as food vehicle for iron fortification estimated by the prophylactic method.

Microencapsulated ferrous sulfate (SFE-171) and ferric orthophosphate in Petit-Suisse cheese were examined for iron bioavailability by the prophylactic method. The iron sources were industrially added to different samples of Petit-Suisse cheese, which were mixed with other food components in our laboratory before use. A reference standard diet inclusive of nonmicroencapsulated ferrous sulfate and a control diet low in iron content were prepared in the laboratory. The final iron content in the fortified diets was approximately 15 mg Fe/kg diet. These diets were administered to weaning rats for 23 days. The iron bioavailability was evaluated as the ratio of iron incorporated into hemoglobin to oral iron intake, thereby being estimated as 62.6 +/- 8.8% for ferrous sulfate and 59.2 +/- 10.6% for SFE-171, which were significantly effective at p < 0.01 compared to 43.4 +/- 10.5% for ferric orthophosphate. It thus turned out that SFE-171 was stable through industrial processing with Petit-Suisse cheese as the food vehicle and served as an iron fortifier equal to ferrous sulfate in bioavailability.

Iron fortification of flour with a complex ferric orthophosphate

The unexpectedly low bioavailability in humans of elemental iron powder prompted us to search for other Fe compounds suitable for Fe fortification of flour that fulfill the two requirements of insolubility in water (due to high water content of flour) and good bioavailability in humans. Systematic studies of compatibility, solubility, and bioavailability led to this study of a microcrystalline complex ferric orthophosphate (CFOP), Fe3H8(NH4)-(PO4)6.6H2O, a well-defined compound. This compound was labeled with 59Fe, and the native Fe in meals was labeled with 55FeCl3. The ratio of absorbed 59Fe to absorbed 55Fe is a direct measure of the fraction of CFOP that joins the nonheme Fe pool and that is made potentially available for absorption. The relative bioavailability of CFOP varied from 30% to 60% when labeled wheat rolls were served with different meals. The CFOP meets practical requirements of an Fe fortificant for flour well, with regard to both compatibility and bioavailability in humans.

Comparison of in vitro, animal, and clinical determinations of iron bioavailability: International Nutritional Anemia Consultative Group Task Force report on iron bioavailability

Relative bioavailability of two iron fortificants, electrolytic Fe and ferric orthophosphate, was related to that of the reference ferrous sulfate with in vitro and rat model depletion-repletion methods in four laboratories to compare values directly with those obtained in a parallel human study. In vitro testing was performed on Fe compounds with both solubility and dialysis in a simulated in vitro gastrointestinal digestion system. Two depletion-repletion techniques, hemoglobin-regeneration efficiency (HRE) and an official method of the Association of Official Analytical Chemists (AOAC), were examined. AOAC relative biological values (RBV) of electrolytic Fe were 0.66 and 0.78 and of FePO4 were 0.25 and 0.34. HRE values were 0.78 and 0.58 for electrolytic Fe and FePO4, respectively. When compared with FeSO4 in a radiolabeled farina-based meal fed to humans, the RBV of FePO4 was 0.25 and electrolytic Fe 0.75. Results obtained with the AOAC method serve as the most reliable prediction of Fe bioavailability in the human although in vitro dialysis is a promising screening technique.

The EFG in oxonium ferric orthophosphate hydrate and related compounds

The point cherge model was used to interpret the small quadrupole spilting of Fe3H15(PO4)8·5H2O by comparing it with related phosphates of known structure. The approximation is sufficient as long as octahedrally coordinated compounds are compared for which Vzz and η do not change their signs.

Hyperfine interactions in an oxonium ferric orthophosphate

Mössbauer and structure data of Fe 3H 15(PO 4) 8·5H 2O are discussed in detail. The small quadrupole interaction in this orthophosphate can be compared with a series of related compounds by use of a point charge model. The quadrupole splitting undergoes a relaxation collapse above 300 K. Below 27 K a ferrimagnetic ordering is found. It shows complicated temperature and external field dependences. The experimental data can be explained by a canted spin model for the A- and B-sublattices, where two unit cells of the crystal combine to a magnetic unit cell.

Effect of Acid Pretreatment on the Stability of EDTA, Cysteine, Lactic and Succinic Acid Complexes of Various Iron Sources in a Wheat Flake Cereal

An in vitro incubation at pH 2 of EDTA, cysteine, lactic or succinic acids with each of five iron sources, [hydrogen (HRI) and electrolytically reduced elemental iron (ERI), ferric chloride (FeCl3), ferrous sulfate (FeSO4) and ferric orthophosphate (FOP)] at a 10:1 molar ratio (ligand:iron) was evaluated for its effect on iron solubilization in a wheat flake cereal subjected to a sequential gastrointestinal pH treatment from endogenous pH (E) to 2 to 6. Incubation significantly enhanced the iron solubilizing potential of EDTA at each pH with HRI and ERI, while lactic and succinic acids were similarly effective with FeSO4 and FeCl3 at pH 2. The reducing potential of cysteine, along with its role as a ligand, generated substantial amounts of Fe+ 2 (pH 2) at the apparent expense of complexed iron. However, with the exception of ERI (pH E), incubation did not increase cysteine's effectiveness in producing more soluble iron (ionic + complexed). This indicates that pH was the major solubilizing factor. Due to FOP's relative insolubility, incubation proved ineffective in all instances. These in vitro results indicate that acid incubation to form a ligand-iron complex has the potential to improve bioavailability of iron.

Effect of Sucrose, Fructose and Aspartame on Fortificant Iron Solubility in a Wheat Flake Cereal

The iron solubilizing effect of three sweeteners (sucrose, fructose and aspartame) in a processed wheat flake cereal fortified with either ferric orthophosphate, hydrogen-reduced or electrolytically-reduced elemental iron was evaluated at various stages during a simulated in vitro gastrointestinal digestion. Added sweetener had little influence on soluble iron over controls, regardless of pH, iron or sweetener source, although effects may have been masked by various cereal components known to complex iron.

EFFECT OF ACID PRETREATMENT ON THE STABILITY OF CITRIC AND MALIC ACID COMPLEXES WITH VARIOUS IRON SOURCES IN A WHEAT FLAKE CEREAL

An in vitro incubation at pH 2 of citric and malic acids with each of five iron sources [(hydrogen (HRI) and electrolytically reduced elemental iron (ERI), ferric chloride (FeCl3), ferrous sulfate (FeSO4) and ferric orthophosphate (FOP)] at a 10:1 molar ratio (acid:iron) was evaluated for its effect on iron solubiliza-tion in a wheat flake cereal subjected to a sequential gastrointestinal pH treatment from endogenous pH (E) to 2 to 6. Citric acid maintained significantly more complexed and ionic iron (Fe+3) in solution than malic acid, with and without incubation, through the final stage of the sequential pH treatment with each of the five iron sources. However, the malate treated samples were affected less than the citrate by acidification from pH E to 2, with less of the soluble complexed iron being insolubilized and significantly more ionic iron (Fe+2) being produced. Incubation significantly enhanced the iron solubilizing capacity of citrate at all stages of the sequential pH treatment with HRI and at pH E with ERI, FeCl3 and FeSO4, As well, incubation increased the iron solubilization properties of malate at all stages with FeSO4 and at E and 2 with HRI and ERI. These results indicate that acid incubation to form an organic acid-iron chelate, particularly with elemental iron, has the potential to improve cereal iron fortificant bioavail-ability.

X-ray powder diffraction and57Fe Mössbauer spectroscopy study of the thermal breakdown of vivianite, Fe3(PO4)2.8H2O

Ferric phosphates resulting from the thermal breakdown of natural Fe3(PO4)2.8H2O are studied by X-ray powder diffraction and Mossbauer spectroscopy. Total iron oxidation and water release give rise to an amorphous material. During heating, a transitional cristobalite-type ferric orthophosphate recrystallizes prior to the stable berlinite-type. The main additional final product is a poorly characterized “Fe3PO7” phase with iron in octahedral coordination.

Effect of Acid Pretreatment on the Stability of Ascorbic Acid Complexes with Various Iron Sources in a Wheat Flake Cereal

ABSTRACTThe effect of acid incubation of ascorbic acid with each of five iron sources (ferrous sulfate, ferric chloride, ferric orthophosphate, hydrogen and electrolytically reduced iron) on iron solubilization in a wheat flake cereal was evaluated. Incubation produced more soluble iron at pH 2 but not necessarily at the endogenous pH of the cereal nor at pH 6. At pH 2, Fe+2 rather than Fe +3 was produced, apparently by a reduction of bound Fe +3 and subsequent release of Fe+2. At pH 6, the soluble iron was mainly in a complexed form. This indicates that acid incubation with ascorbate might facilitate bioavailability of iron if it were incorporated by fortification techniques.

Effects of Baking and Boiling on the Ability of Selected Organic Acids to Solubilize Iron from a Corn‐Soy‐Milk Food Blend Fortified with Exogenous Iron Sources

ABSTRACTCombinations of selected organic acids (ligands) and iron sources were evaluated for their ability to improve iron solubility in a comsoy‐,milk (CSM) food blend. Iron solubility of baked CSM was primarily affected by exogenous iron source at endogenous pH (5.2 ‐ 6.3), and by organic acid at pH 2.0. Boiled CSM samples were directly influenced by pH (range 5.2 ‐ 6.4), and by both organic acid and exogenous iron source at pH 2. Supplementation of baked CSM with hydrogen reduced elemental Iron and either ascorbic or citric acid; or supplementation of boiled CSM with ferric orthophosphate and either cysteine, ascorbic, citric, or malic acid, was shown to provide greatest potential for promoting iron availability in man as measured by chemical means.

In vitro studies on chelating agents as potential iron absorption promoters

Ligands which can bind iron to keep it in solution with good stability at the neutral or alkaline pH of the small intestine can serve as useful absorption promoters of dietary iron. A number of biologically compatible compounds were screened in vitro for this ability at pH 7·5, employing three different systems. Studies carried out with iron-amino acid complexes have shown that amino acids and their derivatives were stable only in the acid pH range with stability constants of 10·9 or lower. Compounds which could solubilize insoluble ferric orthophosphate at pH 7·5 exhibited efficiencies in the order: hydroxamate of lysine > nicotinic acid > EDTA > ascorbic acid > picolinic acid > cysteine. A large number of compounds were tested for their ability to keep iron in solution at pH 7·5 at different iron: ligand ratios. Of these, ascorbic acid, inorganic polyphosphates, hydroxamates of nicotinic acid and lysine, EDTA, caffeic acid, citric acid, xanthurenic acid and phytic acid showed high chelating ability. Some of these compounds can be further exploited as iron absorption-promoting ligands.

Complexation, Stability and Behavior of L-Cysteine and L-Lysine with Different Iron Sources

Effective stability constants for cysteine and lysine with five different iron sources were evaluated along with their behavior in solution. The values obtained for ferric chloride-cysteine, ferrous sulfate-cysteine, ferric chloride-lysine, ferrous sulfate-lysine, hydrogen-reduced lysine, and electrolytic-reduced lysine were 6.81 × 102 to 2.78 × 103, 1.33 × 105 to 1.36 × 105, 6.00 × 10−4 to 7.64 × 10−3, 6.37 ×10−4 to 4.82× 10−3, 9.34 × 10−2 to 1.38 × 10−1, and 4.18 × 10−4 to 7.27 × 10−4, respectively. No measurable complexation occurred with hydrogen- and electrolytic-reduced iron with cysteine nor with ferric orthophosphate and cysteine or lysine. The stability of soluble ferric cysteine over the pH range 2.0 to 7.4 indicates that this complex has the potential to be used as an iron additive in food. Approximately half of the hydrogen and electrolytic reduced iron and only 0.11% of ferric orthophosphate were soluble in acid, whereas ferric chloride and ferrous sulfate were completely soluble. Qualitative evaluation of the iron-amino acid systems over a range of pH from 2.0 to 12.0 indicated that there was a mixed valence state of free iron in most cases with low pH favoring reduction and high pH oxidation, until precipitation of iron hydroxides occurred.

8 - Iron Deficiency in the Tropics

Iron in food is classified as belonging to the haem pool, the nonhaem pool, and extraneous sources. Haem iron is derived from vegetable and animal sources with varying bioavailability. Hookworm infestation of the intestinal tract affects 450 million people in the tropics. Schistosoma mansoni caused blood loss in 7 Egyptian patients of 7.5- 25.9 ml/day which is equivalent to a daily loss of iron of .6-7.3 mg daily urinary loss of iron in 9 Egyptian patients. Trichuris trichiura infestation by whipworm is widespread in children with blood loss of 5 ml/day/worm. The etiology of anemia in children besides iron deficiency includes malaria, bacterial or viral infections, folate deficiency and sickle-cell disease. Severe infections cause profound iron-deficiency anemia in children in central American and Malaysia. Plasmodium falciparum malaria-induced anaemia in tropical Africa lowers the mean haemoglobin concentration in the population by 2 g/dI, causing profound anaemia in some. The increased risk of premature delivery, low birthweight, fetal abnormalities, and fetal death is directly related to the degree of maternal anemia. Perinatal mortality was reduced from 38 to 4% in treated anemic mothers. Mental performance was significantly lower in anemic school children and improved after they received iron. Supplements of iron, soy-protein, calcium, and vitamins given to villagers with widespread malnutrition, iron deficiency, and hookworm infestation in Colombia reduced enteric infections in children. Severe iron-deficiency anemia was treated in adults in northern Nigeria by daily in Ferastral 10 ml, which is equivalent to 500 mg of iron per day. Choloroquine, folic acid, rephenium hydroxynaphthoate, and tetrachlorethylene treat adults with severe iron deficiency from hookworm infestation in rural tropical Africa. Blood transfusion is indicated if the patient is dying of anaemia or is pregnant with a haemoglobin concentration 6 gm/dl. In South East Asia, mg per day prevented iron-deficiency anaemia in pregnancy. Field-trials on nutritional iron deficiency include an acidified milk formula plus ferrous sulphate for infants; biscuits with added bovine hemoglobin for children in Chile; sugar plus sodium ferric EDTA in Guatemala; salt with ferric orthophosphate and sodium acid sulphate in India; and Salt with ferrous sulphate plus sodium hexametaphosphate.

In Vitro Estimation of Relative Iron Availability in Breads and Meals Containing Different Forms of Fortification Iron

ABSTRACTAn in vitro method was used to estimate relative availabilities of eight iron fortification sources under a variety of conditions. The eight iron sources examined were: ferrous sulfate, ferric orthophosphate, ferric sodium pyrophosphate, ferrous fumarate, reduced iron (hydrogen), reduced iron (carbonyl) and two sources of reduced iron (electrolytic). When incorporated into breads or complex meals, seven of the sources tested showed only slight differences in relative availability compared to the ferrous sulfate control. Ferric orthophosphate showed consistently lower relative availability. The baking process did not substantially alter the relative availabilities of nonheme iron in breads and meals containing the different iron fortification sources. Variation in meal composition had a greater influence on the availability of the nonheme iron in the meal than the form of fortification iron incorporated into the meal.

Effects of Storage on the Bioavailability and Chemistry of Iron Powders in a Heat‐Processed Liquid Milk‐Based Product

ABSTRACTRelative Biological Value (RBV) was determined by hemoglobin repletion after 6 and 12 mo storage of a canned milk‐based product which contained 25% U.S. RDA for iron from either ferric orthophosphate (FOP), electrolytic iron (EI), or carbonyl iron (CI). RBV's for the two elemental iron sources were comparable to the RBV of ferrous sulfate and were significantly greater (P &lt;0.01) than the RBV for FOP after each storage period. Significant differences in RBV's for a given iron source were not observed between the two storage periods. A markedly greater percentage of iron from CI and EI than from FOP was solubilized and found in the ferrous form.