, Description:TECHNICAL FIELD
The present disclosure generally relates to the field of fortification of food with iron. More particularly, the present disclosure relates to an irregular and porous elemental iron powder, which is suitable for fortifying food and pharmaceuticals with iron, and a composition comprising the same. The present disclosure also relates to a simple, economic, and efficient method for producing the iron powder. The present disclosure further relates to an iron-fortified beverage or food product fortified with the elemental iron powder and a method of preparing the same.

BACKGROUND OF THE DISCLOSURE
Iron is one of the most essential micronutrients for human and animal nutrition. It forms the functional part of haemoglobin, myoglobin and cytochromes. Iron is also essential in the production of ATP (Adenosine Triphosphate) which releases energy from food. Deficiency of iron leads to tiredness and fatigue in adults. The cognitive development of adults and young children also depends on iron. Iron is chiefly present in two forms i.e. in animal-based proteins (heme-iron) and plant-based proteins (non-heme iron). Heme iron is present in animal foods like meat, fish etc. whereas non-heme iron is in cereals, vegetables, fruits etc. Furthermore, the iron in heme iron is most readily absorbed than non-heme iron by the human body. Iron deficiency is more prominent in the reproductive and lactating women in addition to younger children. A severe form of iron deficiency is anaemia, which is a conundrum especially in developing countries. The iron demands are met by either supplementation, dietary diversification or fortification strategies.

Food fortification is related to addition of relatively small dosages of micronutrients in regular food items such as wheat flour, rice, salt, milk etc. to create a sustained and wider impact in a cost-effective manner. Globally, food is fortified typically with folic acid and Vitamin A along-with iron. The choice of compound used in fortification is often a compromise between reasonable cost, bioavailability and the acceptance of any sensory changes. Fortification with iron poses a unique challenge because the iron compounds that are known to have the best bioavailability interact very strongly with food constituents to produce undesirable organoleptic changes.

Bioavailability of a compound is often quantified in terms of ‘Relative Bioavailability’ (RBV) which is in comparison to a reference, often a compound of known and higher bioavailability like Ferrous Sulphate (FeSO4). The chemical iron compounds such as ferrous sulphate, ferrous fumarate, ferric phosphates and NaFeEDTA (sodium iron ethylenediaminetetraacetate) are widely used in the food fortification owing to their high bioavailability. However, these compounds interact with the food vehicle causing undesirable organoleptic properties of the food.

Alternatively, elemental iron forms such as carbonyl, electrolytic and reduced iron powders where iron is present in its zero-valent state is relatively non-reactive when added to food vehicles like wheat flour. However, they have relatively lower bioavailability than the chemical counterparts but more importantly are available at lower costs; which is imperative to make food fortification type of programs sustainable in the long-term. Hence, they have been used globally in various fortification programs.

Carbonyl and electrolytic forms of iron known in the art produce iron powders of very high-purity and are relatively standardized processes in comparison to reduction method of producing iron powders. Carbonyl iron powders are characterized with very high-purity and ultrafine and dense particle sizes (typically below 10 µm) whereas electrolytic iron is a flaky and high-purity iron powder whose particle sizes are controlled by grinding process and then sieved as per desirable particle size. Reduced iron is relatively cheaper than carbonyl and electrolytic processes. Reduced iron is produced when iron oxide is subjected to reducing agents such as hydrogen or carbon monoxide to remove the oxygen under optimized temperature, time and pressure.

Purity and surface area and other parameters such as particle size are important influencing factors of the bioavailability and need to be tailored to obtain high bioavailability. Purity of the final product depends on the purity of iron oxide employed and processing parameters. A good surface area value could be due to surface features like striations on the surface of a dense iron powder which is prominent in electrolytic iron powders or due to a porous morphology which is the case with the reduced iron.

There are two established and accepted methodologies to predict the actual bioavailability inside the human as human trials are very expensive and time consuming. An in-vitro method is the ferritin expression in the Caco-2 cell method after a coupled gastrointestinal digestion which is very quick. Another method which is an in-vivo method is the AOAC haemoglobin repletion tests in rats. As per the available literature, the highest reported relative bioavailability with respect to FeSO4 has been reported of the carbonyl, electrolytic and H-reduced iron at 66%, 70% and 54% respectively, as per AOAC rat haemoglobin repletion tests.

Methods of the art disclose production of reduced iron at higher temperatures (preferably above 1000oC) in a belt furnace with carbonaceous substances and under hydrogen atmosphere or a combination of both. Such process however results in iron powder having low dissolution of 79% in 0.1N HCl (pH=1) after 30 mins. Prior art also teaches production of a high surface area iron powder of greater than 3 m2/g by the mechanical fluid bed process, where 100% dissolution in 0.1N HCl was achieved in atmost 20 mins. However, surface oxidation by oxygen is necessary due to the high surface area in the process that suggests that the powder has some iron oxides that may compromise the purity of final product and bioavailability at unfavourable acidic conditions i.e. at higher pH which is indispensable in digestion-absorption process inside the body. As an alternate method to improve the bioavailability, prior art teaches a coated iron powder that includes an adjuvant, such as a catalyst, to increase the bioavailability of the iron. Furthermore, there is absence of any in-vitro as well as in-vivo studies for bioavailability in the prior-art that claim a high elemental iron-bioavailability when practically added to any food vehicle like wheat flour or rice.

Accordingly, there is a need in the art for providing reduced elemental iron powder and method of preparation thereof, having desired characteristics such as purity, surface area and particle size which result in high bioavailability when used in fortification of food.

SUMMARY OF THE DISCLOSURE
The present disclosure relates to elemental iron powder having metallic iron content of at least about 98%, wherein the elemental iron powder has a surface area ranging from about 0.5 m2/g to about 1.0 m2/g.

In some embodiments of the present disclosure, the elemental iron powder has an average particle size ranging from about 10 microns to about 18 microns, apparent density ranging from about 0.75 g/cc to about 1.1 g/cc, tap density ranging from about 1.15 g/cc to about 1.7 g/cc and/or Hausner ratio of at least about 1.5. In some embodiments of the present disclosure, purity of iron in the elemental iron powder is at least about 98%.

The present disclosure also relates to a method of producing the said elemental iron powder, wherein the method comprises steps of:
reacting iron oxide with a reducing agent at a temperature ranging from about 650°C to about 800°C for about 240 minutes to 300 minutes to obtain reduced iron,
cooling the reduced iron, and
milling the cooled iron to obtain the elemental iron powder,
wherein the milling is carried out by impact forces or shear forces or cutting forces or a combination thereof.

The present disclosure also relates to an elemental iron powder obtained by the aforesaid method.

The present disclosure also relates to a composition comprising the said elemental iron powder.

The present disclosure also relates to applications of the said elemental iron powder or composition thereof in food fortification.

The present disclosure relates to an iron-fortified food product characterised in that the beverage or the food product is fortified with the elemental iron powder of the present disclosure.

The present disclosure further relates to a method of preparing an iron-fortified food product, characterised in that the elemental iron powder of the present disclosure is added to a food product.

BRIEF DESCRIPTION OF THE ACCOMPANYING FIGURES
In order that the disclosure may be readily understood and put into practical effect, reference will now be made to exemplary embodiments as illustrated with reference to the accompanying figures. The figures together with a detailed description below, are incorporated in and form part of the specification, and serve to further illustrate the embodiments and explain various principles and advantages, in accordance with the present disclosure where:

Figure 1 depicts a flowchart illustrating a method for producing high purity and large surface area iron powder, according to an exemplary embodiment of the present disclosure.
Figure 2 depicts graphical representation of X-ray powder diffraction (XRD) analysis of spray roasted iron oxide powder (raw material) employed in the present method of producing iron oxide.
Figure 3 depicts graphical representation of XRD analysis of irregular iron powder obtained by reduction of spray roasted iron oxide in the method of the present disclosure.
Figure 4 depicts Scanning Electron Microscopy (SEM) microstructure of the reduced iron powder of (a). Example 1, (b). Example 2, and (c). Example 3, at a magnification of 7000X.
Figure 5 depicts Hemoglobin repletion results in the rats for different iron powders.

DETAILED DESCRIPTION OF THE DISCLOSURE
In view of the drawbacks associated and to remedy the need created by the art, the present disclosure aims to provide high bioavailability elemental iron powder, a simple, economical and efficient method of producing the same, and applications thereof.

However, before describing the disclosure in greater detail, it is important to take note of the common terms and phrases that are employed throughout the instant disclosure for better understanding of the technology provided herein.

With respect to the use of substantially any plural and/or singular terms herein, those having skill in the art can translate from the plural to the singular and/or from the singular to the plural as is appropriate to the context and/or application. The various singular/plural permutations may be expressly set forth herein for sake of clarity. The use of the expression “at least” or “at least one” suggests the use of one or more elements or ingredients or quantities, as the use may be in the embodiment of the disclosure to achieve one or more of the desired objects or results. Throughout this specification, the word “comprise”, or variations such as “comprises” or “comprising” or “containing” or “has” or “having” wherever used, will be understood to imply the inclusion of a stated element, integer or step, or group of elements, integers or steps, but not the exclusion of any other element, integer or step, or group of elements, integers or steps.

As used herein, the term "method" and “process” are employed interchangeably.

As used herein, the term "elemental iron powder" and “iron powder” are employed interchangeably and refer to reduced iron powder having an irregular and porous morphology, a metallic iron content of at least about 98%, and surface area ranging from about 0.5 m2/g to about 1.0 m2/g.

As used herein, the term "milling" and “pulverising” are employed interchangeably and refer to breaking down of coarser particles to desirable finer sizes.

As used herein, the term "metallic iron content" refers to the iron present in its zero-valent state. The metallic iron content in the elemental iron powder of the present disclosure is at least about 98%.

As used herein, the term "purity of iron" refers to total iron content of the iron powder. Purity of iron in the elemental iron powder of the present disclosure is at least about 98%.

As used herein, the term "impact forces" refers to forces applied on the material to be ground through continuous impact or collision facilitated by a moving harder grinding media. Apparatus such as but not limiting to hammer mill can be employed to apply grinding by impact forces only.

As used herein, the term “cutting forces” refers to forces applied on the material to be ground through a continuously moving sharp and harder grinding media.

As used herein, the term “shear forces” refers to forces applied on the material to be ground through one-dimensional, two-dimensional or three-dimensional forces acting against each other facilitated by a continuously moving harder grinding media.

As used herein, the term "combination of cutting and shear forces" refers to combination of both forces applied on the material to be ground through continuous shear or cutting action facilitated by a moving grinding media. Apparatus such as but not limiting to cutting mills can be employed to deploy the grinding by both cutting and shear forces.

As used herein, the term "combination of impact and shear forces" refers to combination of both forces applied on the material to be ground through continuous impact or collision along with shear action facilitated by a moving grinding media. Apparatus such as but not limiting to centrifugal mills and rotor beater mills can be employed to deploy grinding by combination of impact and shear forces.

As used herein, the term "tap density" and “tapped density” have been used interchangeably. The tapped density of a powder is the ratio of the mass of the powder to the volume occupied by the powder after it has been tapped for a defined period of time. Tapped density values are higher for more regularly shaped particles as compared to irregularly shaped particles. The elemental iron powder of the present disclosure has tapped density ranging from about 1.15 g/cc to about 1.7 g/cc.

As used herein, the term "apparent density" refers to the bulk density of the powder. It provides the mass per unit volume of loose packed powders. A low apparent density can be an indication of fine particles and a high apparent density can be an indication of large particles. The elemental iron powder of the present disclosure has an apparent density ranging from about 0.75 g/cc to about 1.1 g/cc.

As used herein, the term "Hausner ratio" refers to the ratio of Tapped Density/Apparent Density. Higher Hausner ratio indicates irregularity of the iron powder. The Hausner ratio of the elemental iron powder of the present disclosure is at least about 1.5.

As used herein, the term "room temperature" refers to a temperature ranging from about 20°C to about 40°C.

As used herein, the term “food product” refers to a substance that can be used or prepared for use as food. It includes but is not limited to powders, liquids or beverages, grains, minerals, or commercially produced foods made for consumption by humans, domestic animals or wild animals.

As used herein, the term "about" means to be nearly the same as a referenced number or value. As used herein, the term "about" should be generally understood to encompass ± 10% of a specified amount or value.

The present disclosure relates to a method for producing high-bioavailability elemental iron powder from iron oxide, and the elemental iron powder obtained thereof which is suitable for fortifying food and pharmaceuticals with iron.

The key properties required for achieving good bioavailability of iron powder in food fortification includes:
1. Purity: Highest possible purity is preferable because higher the iron fed into body, higher is the probability for absorption
2. Surface Area: The measure of surface area is done by BET principle. Higher the surface area higher would be reactivity and absorption inside the body
3. Particle Size Distribution (PSD): Finer particle sizes promote the bioavailability. However, too fine iron powder particles (like in carbonyl) are very expensive and not sustainable for food fortification application.
4. Hausner Ratio: Hausner Ratio is ratio of Tapped Density/Apparent Density. This property may also be related to morphology of powder. Higher Hausner ratio indicates irregularity of the iron powder. Correlation of the Hausner ratio to the flow behaviour of powder is provided in Table 1. Lower ratio indicates good packing and flow behaviour.

Table 1:
Flow Character Hausner Ratio
Excellent/very free flow 1.00-1.11
Good/free flow 1.12-1.18
Fair 1.19-1.25
Passable 1.26-1.34
Poor/cohesive 1.35-1.45
Very Poor/very cohesive 1.46-1.59
Very, very poor/approx. non-flow >1.60

Thus, the present disclosure provides for elemental iron powder having high bioavailability.

The elemental iron powder of the present disclosure has a metallic iron content of at least about 95% and a surface area ranging from about 0.5 m2/g to about 1 m2/g.

In some embodiments, the elemental iron powder of the present disclosure has a porous & irregular morphology, high surface area, high purity and desirable particle size.

The higher bioavailability of iron powders of the present disclosure is primarily due to its unique combination of chemical purity of iron as well as the surface area which is a consequence of its irregular-porous morphology. The irregularity of the iron powders is related to the very high Hausner ratios of at least 1.5. The porosity of the iron powders is related to the high specific surface areas. The very high chemical purity of the iron powder ensures that the maximum possible extent of iron is available for dissolution and the high surface area ensures maximum contact of the gastric and intestinal juices with the powder due to which the kinetics of the above reactions are rapid.

In some embodiments of the present disclosure, surface area of the elemental iron powder is ranging from about 0.5 m2/g to about 0.9 m2/g.

In some embodiments of the present disclosure, surface area of the elemental iron powder is ranging from about 0.5 m2/g to about 0.862 m2/g.

In some embodiments of the present disclosure, purity of iron in the elemental iron powder is at least about 98%.

In some embodiments of the present disclosure, the purity of iron in the elemental iron powder is about 98%, about 98.1%, about 98.2%, about 98.3%, about 98.4%, about 98.5%, about 98.6%, about 98.7%, about 98.8%, about 98.9%, about 99%, about 99.1%, about 99.2%, about 99.3%, about 99.4%, about 99.5%, about 99.6%, about 99.7%, about 99.8%, about 99.9% or about 100%.

In some embodiments of the present disclosure, the particle size distribution of the elemental iron powder is ranging from about 25 µm to about 38 µm.

In some embodiments of the present disclosure, the particle size distribution of the elemental iron powder is ranging from about 25 µm, 26 µm, 27 µm, 28 µm, 29 µm, 30 µm, 31 µm, 32 µm, 33 µm, 34 µm, 35 µm, 36 µm, 37 µm or 38 µm.

In some embodiments of the present disclosure, average particle size of the elemental iron powder is ranging from about 10 microns to 18 about microns.

In some embodiments of the present disclosure, the average particle size of the elemental iron powder is about 10 microns, about 11 microns, about 12 microns, about 13 microns, about 14 microns, about 15 microns, about 16 microns, about 17 microns or 18 about microns.

In some embodiments of the present disclosure, apparent density of the elemental iron powder is ranging from about 0.75 g/cc to about 1.1 g/cc.

In some embodiments of the present disclosure, the apparent density of the elemental iron powder is about 0.75 g/cc, about 0.80 g/cc, about 0.85 g/cc, about 0.90 g/cc, about 0.95 g/cc, about 1.00 g/cc, about 1.05 g/cc or about 1.1 g/cc.

In some embodiments of the present disclosure, tap density of the elemental iron powder is ranging from about 1.15 g/cc to about 1.7 g/cc.

In some embodiments of the present disclosure, the tap density of the elemental iron powder is about 1.15 g/cc, about 1.20 g/cc, about 1.25 g/cc, about 1.30 g/cc, about 1.35 g/cc, about 1.40 g/cc, about 1.45 g/cc, about 1.50 g/cc, about 1.55 g/cc, about 1.60 g/cc, about 1.65 g/cc or about 1.70 g/cc.

In some embodiments of the present disclosure, the Hausner ratio of the elemental iron powder is ranging from about 1.5 to about 1.6, preferably from about 1.51 to about 1.6, more preferably from about from about 1.53 to about 1.59. The high Hausner ratio of the elemental iron powder of the present disclosure indicates irregularity of iron powder.

In some embodiments of the present disclosure, the Hausner ratio of the elemental iron powder is 1.5, 1.51, 1.52, 1.53, 1.54, 1.55, 1.56, 1.57, 1.58, 1.59 or 1.60.

In embodiments of the present disclosure, the aforesaid unique physio-chemical properties of the elemental iron powder of the present disclosure increase the bioavailability of the iron powder.

The present disclosure also relates to a method of producing the said elemental iron powder. The described method is simple, economical, scalable and efficient for producing high bioavailability elemental iron powder.

The method of producing elemental iron powder of the present disclosure comprises steps of:
reacting iron oxide with a reducing agent at a temperature ranging from about 650°C to about 800°C for about 240 minutes to 300 minutes to obtain reduced iron,
cooling the reduced iron, and
milling the cooled iron to obtain the elemental iron powder,
wherein the milling is carried out by impact or shear or cutting forces or a combination thereof.

In some embodiments of the present disclosure, the iron oxide is heated with the reducing agent in a reduction furnace in static bed condition.

In some embodiments of the present disclosure, the step of reacting/ heating iron oxide in presence of a reducing agent is carried out using a suitable heating means in the reduction furnace. During the process of heating the reducing agent, such as any reduction gas, may be supplied at predetermined gas flow rate. In some embodiments of the present disclosure, the minimum gas flow rate may be at-least about 0.5 Nm3/kg of powdered iron oxide.

In some embodiments of the present disclosure, the reducing agent is selected from a group comprising but not limiting to hydrogen and cracked ammonia or a combination thereof.

In some embodiments, any reduction furnace can be employed in the method of the present disclosure such as but not limited to pusher type, steel belt type and walking beam type furnace.

In some embodiments of the present disclosure, the reduced iron obtained in step a) of the method is cooled to room temperature. In some embodiments, the cooling step in the method of producing elemental iron powder is carried out at under inert atmosphere such as but not limiting to in the presence of nitrogen and/or argon.

In some embodiments of the present disclosure, the reduced iron is cooled to a temperature ranging from about 20°C to about 40°C under inert atmosphere in presence of nitrogen or argon or a combination thereof.

In some embodiments, the cooling may be performed by natural cooling or a forced cooling at controlled cooling rate to bring the loosely sintered iron powder cake to room temperature.

In some embodiments of the present disclosure, the cooled iron is subjected to crushing prior to the step of milling, to obtain iron particles having a size of up to about 2 mm.

In some embodiments, the cooled iron is subjected to a crushing process prior to the step of milling. The crushing operation employed in the method of the present disclosure is very gentle in nature to obtain iron powder particles or chunks less than 2 mm for further pulverisation/milling process.

The milling step employed in the method of the present disclosure is very critical to preserve the specific surface area and porous morphology of iron powder particles. Reduced iron powder has very high purity and is inherently ductile in nature. This iron powder, if subjected to strong milling forces may distort the desired irregular-porous morphology of iron powder leading to loss of surface area. The present disclosure therefore carries out the milling by using the principle of only impact forces, shear forces, cutting forces or any combination thereof.

In some embodiments of the present disclosure, the milling is carried out by impact forces, cutting forces, shear forces, combination of impact and shear forces, combination of cutting and shear forces, combination of impact and cutting forces, or combination of impact, cutting and shear forces.

In some embodiments of the present disclosure, the milling is carried out by employing mills selected from a group comprising but not limiting to Hammer mill, Cutting mill, Centrifugal mill and Rotor Beater mill.

In some embodiments of the present disclosure, the milling is carried out by impact forces, cutting forces, shear forces, combination of impact and shear forces, or combination of cutting and shear forces.

In some embodiments of the present disclosure, the method comprises a step of screening the elemental iron powder to obtain powder having the desired particle size. Particle size is also an important property of the desired iron powder property and is screened using any conventionally employed technique. The screening step determines the maximum particle size to yield the desired irregular-porous morphology iron powder with large surface area. In some embodiments, the screening is carried out after milling to obtain powders having a particle size lesser than about 1 mm preferably less than about 40 microns. In an exemplary embodiment of the present disclosure, the sieving step is carried out by sieving with suitable mesh such as but not limiting to a 400-500 mesh sieve.

In an exemplary embodiment of the present disclosure, the method comprises a step of screening the elemental iron powder having particle size lesser than about 40 microns after milling, wherein the screening is carried out using a mesh.

In some embodiments, the method of producing the iron powder comprises steps of heating iron oxide, followed by reducing the heated iron oxide in static bed condition at a temperature ranging from about 650°C to about 800°C for about 240 minutes to 300 minutes, to obtain reduced iron; cooling the reduced iron; and milling the cooled iron to obtain the iron powder.

In some embodiments of the present disclosure, the method of producing elemental iron powder comprises steps of:
reacting iron oxide with a reducing agent at a temperature ranging from about 650°C to about 800°C for about 240 minutes to 300 minutes to obtain reduced iron,
cooling the reduced iron,
crushing and thereafter milling the cooled iron to obtain the elemental iron powder, wherein the milling is carried out by impact forces, cutting forces, shear forces or a combination thereof, and
optionally screening the elemental iron powder.

In some embodiments of the present disclosure, the method of producing elemental iron powder comprises steps of:
feeding powdered iron oxide into a reduction furnace and reacting/heating the iron oxide with a reducing agent such as a reducing gas at a temperature ranging from about 650°C to about 800°C for about 240 minutes to 300 minutes to obtain reduced iron,
cooling the loosely sintered reduced iron powder cake thus obtained to room temperature preferably under inert atmosphere,
crushing the reduced sintered iron cake into particles preferably with a size less than 1 mm and thereafter milling the particles by impact forces, cutting forces, shear forces or a combination thereof to obtain the elemental iron powder, and
optionally screening the milled elemental iron powder.

In some embodiments of the present disclosure, the iron oxide employed in step a) of the method is loaded in the reduction furnace at a bed height ranging from about 10 mm to about 30 mm.

In some embodiments of the present disclosure, the iron oxide employed for the production of iron powder is a powdered iron oxide such as but not limiting to a synthetic powder and may be produced by spray roasting of pickling solution obtained during an acid recovery process in steel making plant. However, this iron oxide is not limited to synthetic iron oxide (such as but not limiting to hematite) but may also be extended to the iron powder obtained from other type of iron oxide ore as well. For instance, the iron oxide may also include iron oxide from other synthetic or natural sources (such as but not limiting to magnetite and/or iron-oxyhydroxide) that has a high iron content.

In an embodiment, iron powder with enhanced surface area and enhanced purity having special physical and chemical properties is produced from industrial by-product material including but is not limiting to iron oxide obtained from spray roasting of acid pickle liquor.

In some embodiments of the present disclosure, the iron oxide includes but is not limited to ferrous oxide, ferric oxide and ferric oxy-hydroxides.

In an exemplary and non-limiting embodiment of the present disclosure, the powdered iron oxide has a composition comprising iron Fe (T) at about 68.61 to 69.38 wt.% , ferrous oxide (FeO) at about 0.35 to 1.03 wt.%, silicon dioxide (SiO2) at about 0.1 to 0.19 wt.%, calcium oxide (CaO) at about 0.012 to 0.06 wt.%, magnesium oxide (MgO) at about 0.01 to 0.02 wt.%, manganese oxide (MnO) at about 0.27 to 0.43 wt.%, aluminium oxide (Al2O3) at about 0.16 to 0.19 wt.%, sulphur (S) at about 0.005 to 0.011 wt.%, carbon (C) at about 0.082 to 0.115 wt.%, along with at least one or more additional elements selected from chromium (Cr), titanium (Ti), copper (Cu) and phosphorus (P) at various wt.% and the balance being incidental elements.

In some embodiments, the iron powder obtained by the process of the present disclosure comprises iron Fe (T) at about 98.2 to 99 wt.% , ferrous oxide (FeO) at about 0.12 to 0.86 wt.%, silicon dioxide (SiO2) at about 0.1 to 0.15 wt.%, calcium oxide (CaO) at about 0.05 to 0.08 wt.%, magnesium oxide (MgO) at about 0.013 to 0.038 wt.%, manganese oxide (MnO) at about 0.45 to 0.478 wt.%, aluminium oxide (Al2O3) at about 0.24 to 0.32 wt.%, sulphur (S) at about 0.002 to 0.007 wt.%, carbon (C) at about 0.02 to 0.09 wt.% with the balance being incidental elements in traces.

A flowchart illustrating the method for producing the elemental iron powder according to an exemplary embodiment of the present disclosure is provided in Figure 1. At block 101, the powdered iron oxide as described above is fed into a reduction furnace such as but not limited to one of pusher type, steel belt type and walking beam type furnace. The powdered iron oxide may be loaded onto a bed portion of the reduction furnace at different heights varying from about 10 mm to about 30 mm. After loading, the powdered iron oxide may be subjected to heating at a temperature range of 650°C to 800°C for about 240 minutes to 300 minutes in a reduction furnace (as shown in block 102). In an embodiment, the heating may be carried out using a suitable heating means in the reduction furnace. Further, the heating is carried out in presence of reduction gas including but not limiting to hydrogen rich gas. In an exemplary embodiment, hydrogen gas may be used as the reduction gas. During the process of heating the reduction gas may be supplied at predetermined gas flow rate. In an embodiment, the minimum gas flow rate may be at-least about 0.5 Nm3/kg of powdered iron oxide. Also, the reductant gas flows in at least one of counter-current direction and concurrent direction to the flow of the powdered iron oxide inside the reduction furnace.

When the iron oxide is made to react with hydrogen in presence of heat energy (heating), a series of reduction reaction may occur leading to the formation of iron powder due to formation of H2O, as shown by below chemical equation below:

Reduction is loss of oxygen atom from a molecule or the gaining of one or more electrons. Reduction of iron oxide may lead to the formation magnetite or wustite as an intermediate product. This is further reduced with the available hydrogen atoms to form metallic iron. The oxygen loss during this reduction corresponds to about 30 wt.%. Time and temperature need to be critically controlled to end up with the iron having desired properties primarily of purity and surface area. An increased time or temperature would result in the formation of strongly sintered iron cake which would compromise the surface area of the reduced iron and further adding to the energy for its pulverisation/milling.

At block 103 of Figure 1, the obtained reduced iron powder cake is cooled in the reduction furnace to room temperature under an inert atmosphere. The inert atmosphere may be created by passing gas such as but not limited to nitrogen into the reduction furnace. Cooling may be performed via natural cooling or with a force cooling at controlled cooling rate to bring the loosely sintered iron powder cake to room temperature. At block 104, the sintered iron powder cake is subjected to a crushing process. This crushing operation is very gentle in nature to obtain iron powder particles or chunks less than 2 mm for the further pulverisation/milling process. The reduced iron powder has very high purity and inherently is very ductile in nature. This iron powder, if subjected to strong milling forces may distort the desired irregular-porous morphology of iron powder leading to loss of surface area. Therefore, pulverisation/milling step (as shown in block 105) is very critical to preserve the specific surface area of iron powder particles and is done using only the principle of impact, cutting or shear forces or a combination thereof.

Particle size is also an important property of the desired iron powder property and is screened (as shown in block 106) using a 400/500-mesh sieve because the physical properties of the iron powder is dependent on the particle size distribution based on the maximum particle size of the iron powder. 400 and 500-mesh sieve corresponds to the maximum particle size of about 38 µm and about 25 µm respectively. The obtained iron powder has the desired irregular-porous morphology.

The combination of the heating conditions (temperature and time period) and the specific milling techniques employed in the method are critical to obtain elemental iron powder with the desired properties. An increased time or temperature would result in the formation of strongly sintered iron cake which would compromise the surface area of the reduced iron and further adding to the energy for its pulverisation. Further, a product obtained on employing higher temperature would have a higher purity but lower surface area and vice-versa.

Employing impact, cutting and/or shear forces for milling renders the method of the present disclosure to be scalable, economical and produce finer sizes of iron powder. Alternate milling techniques may apply strong milling forces distorting the desired irregular-porous morphology of iron powder leading to loss of surface area. Thus, pulverising the sinter cake in the process of the present disclosure by an alternate milling principle such as pressure + friction (mortar-pestle) etc., will alter the properties of the elemental iron powder obtained in the present disclosure (such as AD, TD, Hausner Ratio and/or Surface Area) rendering it unsuitable or less efficient for application in fortification. Thus, although the specific milling step of the present disclosure makes the powder relatively denser (higher AD, TD) it conserves the high irregularity (higher Hausner Ratio) of the powder providing it desired characteristics and improving the bioavailability of the iron powder.

In some embodiments, the screening step employed in the method is also critical to produce reduced iron powder having properties suitable for food fortification.

The elemental iron powder obtained by the method of the present disclosure has unique physical and chemical properties that render it suitable for food and pharmaceutical applications. The iron powder obtained by the method of the present disclosure is characterized by high purity and specific surface area, and additionally characterized by finer particle size range and high Hausner ratio (which is at least 1.5 indicating irregularity of the iron powder). Thereby the iron powder has high solubility and bioavailability of the iron.

In some embodiments of the present disclosure, the elemental iron powder obtained by the method of the present disclosure has one or more characteristics selected from a group comprising: metallic iron content of at least about 98%, purity of at least about 98%, surface area of less than or equal to about 1 m2/g, average particle size ranging from about 10 microns to 18 about microns, apparent density ranging from about 0.75 g/cc to about 1.1 g/cc, tap density ranging from about 1.15 g/cc to about 1.7 g/cc and Hausner ratio of at least 1.5.

In some embodiments of the present disclosure, reducing iron oxide to iron powder as per the method of the present disclosure results in formation of metallic iron. In some embodiments, the metallic iron content of the reduced iron powder is at least about 98 wt%.

In some embodiments, the total iron content of the reduced iron powder is at least about 98.5 wt%.

In some embodiments, the total iron content of the reduced iron powder is at least about 99 wt%.
The reduced iron powder obtained as per the method of the present disclosure is irregular and porous in nature.

In an exemplary embodiment, the microstructure of the reduced iron powder is determined by Scanning Electron Microscopy (SEM).

In an exemplary embodiment, the porosity of the iron powder is measured by BET (Brunauer, Emmett and Teller) method.

Since, WHO recommends electrolytic iron powder for food fortification, a commercial electrolytic iron powder from Industrial Metal Powders (IMP), Pune, is used as the standard of care for comparison of the properties of the iron powder of the present disclosure.

In an exemplary embodiment, the Dissolution rate of the iron powder is tested with 0.1N HCl after about 30 mins. Dissolution is tested to measure the extent and rate at which the iron powders form a solution. The dissolution of iron powder is important for its bioavailability and effectiveness. In some embodiments, the iron powder of the present disclosure has a dissolution rate of at least 80%, preferably at least 90% and more preferably 100%.

In an exemplary embodiment, the dissolution rate of the iron powder of the present disclosure is about 87% better than the standard of care.

In an exemplary embodiment of the present disclosure, estimation of iron is carried out by atomic absorption spectrophotometer (AAS) at about 248.3 nm wavelength.

In some embodiments, the estimation of the bioavailable iron in a fortified food product such as wheat flour is done using various in vitro studies such as absorption of iron by Caco-2 cell model after coupled simulated gastrointestinal digestion, and in-vivo studies such as the AOAC haemoglobin repletion studies in rats.

In an exemplary embodiment of the present disclosure, the bioavailability of iron is assessed using coupled in vitro digestion/Caco-2 cell model in the absence or presence of ascorbic acid. Desired quantity of the fortified food product (such as but not limiting to flour) is weighed in the presence and absence of ascorbic acid (about 1:10 molar ratio) in a suitable container and suspending in saline, adjusting the pH to about 2.8. Pepsin is then added and the final volume of the sample is made up with NaCl. The container is immersed in a shaking water-bath at about 37oC for about 120 min. At the end of gastric digestion, the pH of the digesta was adjusted to 6.5, supplemented with pancreatin and bile extract (0.2 g & 1.2 g/100mL 0.1 N NaHCO3). The sample is again incubated for about 2h. At the end of intestinal digestion, the digesta was boiled for about 10 mins in a water bath to inactivate the digestive enzymes followed by feeding the digesta to differentiated Caco-2 cells in triplicates for a period of about 4 h. After about 4 h, the digesta was replaced with fresh MEM and incubation was continued for about 20 h. At the end of the incubation the cells were washed, lysed and ferritin content in the cell lysate was analyzed. Cellular ferritin induction, was expressed as in terms of ng ferritin/mg protein, is considered as the index of in-vitro iron bioavailability. The ferritin formation of the FeSO4 is taken as the standard reference and is considered as 100%. The percentage of ferritin induction in the Caco-2 cells treated with other elemental iron powders with respect to the cells treated with reference FeSO4 is considered as the Relative Bioavailability (RBV) of the iron powder.

In an exemplary embodiment, the Relative Bioavailability (RBV) of the iron powder of the present disclosure is about 48% to about 63% better than the standard of care in absence of ascorbic acid, and about 45% to about 62% better than the standard of care in presence of ascorbic acid. The effect of an iron-absorption enhancer like ascorbic acid as a similar effect on bioavailability of iron powders to that of FeSO4.

In an exemplary embodiment of the present disclosure, Haemoglobin repletion tests are carried out in rats to determine the relative biological value (RBV) of the elemental iron powder of the present disclosure. Hb-Fe is calculated, by assuming the total blood volume of the rat as 6.7% and percentage of iron in the hemoglobin as 0.335%. The following equations were used to calculate the relative biological value of the iron powders.
HbFe (mg)=((Body weight (g)×Hb (g/L)×6.7×0.335))/10000
%Hemoglobin Regeneration Efficiency (%HRE)=((HbFe_Final-HbFe_initial))/(Fe_intake (mg))
RBV=((%HRE test group))/((%HRE FeSO4 group))×100

In embodiments of the present disclosure, the elemental iron powder obtained by the process of the present disclosure has better bioavailability than elemental iron powder produced by any conventional powder production process such as but not limiting to electrolytic, carbonyl, atomization etc.

The elemental iron powder of the present disclosure is suitable for use as an additive in food, beverages and pharmaceuticals.

The heavy metal content (such as Arsenic, Lead and Mercury) in the elemental iron powder of the present disclosure is well below the maximum permissible limits as per Food Chemical Codex.

The present disclosure thus provides a simple, cost-effective, non-toxic and efficient method of producing high bioavailability iron powder. Said iron powder with high purity and surface area could be used in the food fortification segment and would be a very suitable alternative to existing elemental iron powder forms. It could also be advantageous to use this iron powder instead of iron salts due to better organoleptic properties, stability and lower costs. The rapid dissolution and high bioavailability of the iron powder also render it suitable for applications in the nutraceutical and pharmaceutical segments as a source of iron and manufacturing of high purity and bioavailability iron compounds/materials.

The present disclosure also pertains to a composition comprising the elemental iron powder as described above.

In some embodiments of the present disclosure, the composition further comprises one or more excipient such as a pharmaceutically acceptable excipient.

The present disclosure envisages any excipient that enhances or aids iron absorption in a subject in need thereof. In an exemplary embodiment of the present disclosure, the pharmaceutically acceptable excipient present in the composition is selected from a group comprising but non-limiting to ascorbic acid, vitamin A and ethylenediaminetetraacetic acid (EDTA) or a combination thereof.

In some embodiments of the present disclosure, the composition is in a form selected from a group comprising powder, tablet, capsule, liquid, elixir, syrup, suspension and solution or any combination thereof.

The present disclosure also pertains to an iron-fortified food product characterised in that the food product is fortified with the elemental iron powder of the present disclosure.

The present disclosure also pertains to a method of preparing an iron-fortified food product, characterised in that the elemental iron powder of the present disclosure is added to a food product.

In an exemplary and non-limiting embodiment of the present disclosure, the food products that can be fortified with iron by employing the elemental iron powder of the present disclosure are selected from a group comprising grains, flour, salt, liquids, commercially produced foods etc.

In an exemplary embodiment of the present disclosure, the grains are selected from a group comprising but not limiting to wheat, rice, maize, oat, barley, rye, millet and sorghums.

In an exemplary embodiment of the present disclosure, the flour is that of any grain, preferably wheat including whole-wheat flour, maida, etc.

In some embodiments, the commercially produced foods include any man-made food product such as but not limiting to oil, bread, biscuits, breakfast cereals, dressings, spreads, soups, protein drinks and other beverages etc.

In some embodiments, the food products fortified with iron by employing the elemental iron powder of the present disclosure may optionally be also fortified with one or more additional nutrient such as but not limiting to iodine, vitamins, folic acid etc. For instance, salt may be fortified with iodine and iron (Double Fortified Salt) to cost-effectively deal with micronutrient deficiency.

The amount of the elemental iron powder which is to be employed in the food product is as per the guidelines provided by food regulatory authorities.

In an exemplary embodiment, advantages of the method of the present disclosure and the iron powder produced thereof include but are not limited to:

Provides a simple, cost-effective, scalable, efficient, sustainable and non-toxic means for fortification of food with high bioavailability elemental iron powder, to address the issue of iron deficiencies.
The iron powder has high purity and desirable surface area.
The iron powder has a high Hausner ratio and finer particle size range, high solubility/dissolution rate and increased bioavailability.
The rapid dissolution and high bioavailability of the iron powder produced by the method of the present disclosure, renders it suitable for applications in the nutraceutical and pharmaceutical segments as a source of iron.
The iron powder has better organoleptic properties, stability and lower costs than use of iron salts in food fortification.

Additional embodiments and features of the present disclosure will be apparent to one of ordinary skill in art based on the description provided herein. The embodiments herein provide various features and advantageous details thereof in the description. Descriptions of well-known/conventional methods and techniques are omitted so as to not unnecessarily obscure the embodiments herein.

Any possible combination of two or more of the embodiments described herein is comprised within the scope of the present disclosure.

The foregoing description of the specific embodiments will so fully reveal the general nature of the embodiments herein that others can, by applying current knowledge, readily modify and/or adapt for various applications such specific embodiments without departing from the generic concept, and, therefore, such adaptations and modifications should and are intended to be comprehended within the meaning and range of equivalents of the disclosed embodiments. It is to be understood that the phraseology or terminology employed herein is for the purpose of description and not of limitation. Therefore, while the embodiments in this disclosure have been described in terms of preferred embodiments, those skilled in the art will recognize that the embodiments herein can be practiced with modification within the spirit and scope of the embodiments as described herein.

Any discussion of documents, acts, materials, devices, articles and the like that has been included in this specification is solely for the purpose of providing a context for the disclosure. It is not to be taken as an admission that any or all of these matters form a part of the prior art base or were common general knowledge in the field relevant to the disclosure as it existed anywhere before the priority date of this application.

Further, while the instant disclosure is susceptible to various modifications and alternative forms, specific aspects thereof has been shown by way of examples and drawings and are described in detail below. However, it should be understood that it is not intended to limit the invention to the particular forms disclosed, but on the contrary, the intention is to cover all modifications, equivalents, and alternatives falling within the spirit and the scope of the invention.

EXAMPLES:
The following illustrations in form of examples are described to bring more clarity of the invention and should not be considered as limitation or drawback of the invention.

Example 1: Preparation of Iron powder at reducing temperature of about 650°C
Irregular spray roasted iron oxide powder having the composition as shown in Table 2 below was reduced in pure hydrogen gas in a reduction furnace at 650oC for 280 minutes duration. The minimum flow rate of hydrogen was 0.5 Nm3/kg of iron oxide. The bed height of the iron oxide was 25 mm. The resultant loosely sintered iron powder cake was cooled in the furnace to room temperature by passing nitrogen gas. The sintered iron powder cake was then crushed by jaw crusher, pulverised using impact forces (hammer mill) only and screened through a 400-mesh sieve.

Table 2:
Composition
(wt %) Fe(total)
[Fe(T)]
FeO CaO SiO2 S MgO MnO Al2O3 C
Spray Roasted Iron Oxide 69.38

0.35 0.06 0.1 0.011 0.02 0.43 0.19 0.115

XRD test was carried out on the spray roasted powdered iron oxide and the iron powder obtained using Copper K-Alpha (CuKa) radiation of wavelength 1.54 Å. The diffracted x-ray beam intensity as a function of the diffracted angle was recorded. Position of the planes and their intensity respectively reveal the information about the phase and amount of phase present in the microstructure. Figures 2 and 3 illustrate graphical representation of XRD analysis results for the spray roasted powdered iron oxide and the iron powder, respectively. A set of sharp peaks present at 2?=44.8°, 65.1 and 82.4 indicates the formation of metallic iron after reduction process.

Table 3 shows the detailed chemical analysis for the reduced iron obtained. The reduced irregular and porous iron powder primarily contained metallic iron at 97.9 wt % and possessed a maximum particle size of not more than 38 µm.

Table 3:
Composition (wt %) Fe (total) FeO Fe
(metal) CaO SiO2 C S MgO MnO Al2O3
Iron powder 98.61 0.52
97.9 0.04 0.11 0.03 0.005 0.09 0.433 0.25

Figure 4a illustrates the Scanning Electron Microscopy (SEM) image of the reduced iron powder at a magnification of 7000X. The SEM image clearly depicts the irregular and highly porous morphology of the reduced iron powder.

Example 2: Preparation of Iron powder at reducing temperature of about 700°C
Irregular spray roasted iron oxide powder having the composition as defined in Example 1 was reduced using cracked ammonia gas (hydrogen rich gas) at about 700oC for a reduction time of about 240 minutes. The minimum flow rate of hydrogen was 0.5 Nm3/kg of iron oxide. The bed height of this iron oxide was 20 mm.

The resultant loosely sintered iron powder cake was cooled in the furnace to room temperature by passing nitrogen gas. The sintered iron powder cake was then crushed by using ceramic mortar and pestle, pulverised using a combination of impact and shear forces (centrifugal mill) and screened through a 500-mesh sieve.

Table 4 shows the chemical analysis for the reduced iron thus obtained. The reduced irregular iron powder contained at least 98.1 wt% metallic iron and possessed a maximum particle size not more than 25 µm.

Table 4:
Composition (wt %) Fe (total) FeO Fe
(metal) CaO SiO2 C S MgO MnO Al2O3
Iron powder 98.64 0.52
98.1 0.03 0.13 0.043 0.003 0.052 0.47 0.23

Figure 4b illustrates the Scanning Electron Microscopy (SEM) image of the reduced iron powder at a magnification of 7000X. The SEM image clearly depicts the irregular and highly porous morphology of the reduced iron powder.

Example 3: Preparation of Iron powder at reducing temperature of about 800°C
Irregular spray roasted iron oxide powder having the composition as defined in Example 1 was reduced using cracked ammonia gas (hydrogen rich gas) at about 800oC for a reduction time of about 300 minutes. The minimum flow rate of hydrogen was 0.5 m3/kg of iron oxide. The bed height of this iron oxide was 30 mm.

The resultant loosely sintered iron powder cake was cooled in the furnace to room temperature by passing nitrogen gas. The sintered iron powder cake was then crushed by using jaw crusher and pulverised using cutting and shear forces (cutting mill) and screened through a 400-mesh sieve.

The below Table 5 shows the chemical analysis for the reduced iron thus obtained. The reduced irregular iron powder contained at least 98.8 wt% metallic iron and possessed a maximum particle size not more than 38 µm.

Table 5:
Composition (wt %) Fe (total) FeO Fe
(metal) CaO SiO2 C S MgO MnO Al2O3
Iron powder 99 0.12 98.8 0.05 0.1 0.02 0.007 0.038 0.478 0.24

Figure 4c illustrates the Scanning Electron Microscopy (SEM) image of the reduced iron powder at a magnification of 7000X. The SEM image clearly depicts the irregular and highly porous morphology of the reduced iron powder.

Example 4: Assessing properties of Iron powder
The iron powder obtained from the Examples 1-3 were analyses for their physio-chemical properties viz., Dissolution rate studies and estimation of iron content, Apparent Density, Tapped Density, Hausner Ratio, surface area, and Bioavailability tests (in absence of ascorbic acid, in presence of ascorbic acid and by Haemoglobin repletion tests). WHO recommends Electrolytic Iron Powder which is globally used for food fortification. Commercially used Electrolytic Iron Powder obtained from IMP, Pune is used for comparison of the properties and bioavailability of the iron powders of the present disclosure. The experimental protocol for conducting the experiments is provided hereunder and the results obtained are Tabulated in Table 6.

Dissolution rate studies at 0.1N HCl after 30 mins: Iron powders (40 mg) were weighed into 250 mL conical flasks containing 200 mL of 0.1N HCl and incubated on a shaker at room temperature with a constant stirring for 30 mins. After 30 mins, 0.5 mL aliquot of was collected into 1.5 mL tube and centrifuged at 10,000 rpm for 5 mins. The iron content in the supernatant was analysed by AAS.

Estimation of iron by AAS: After 30 mins incubation the amount of iron solubilised in 0.1N HCl was estimated by atomic absorption spectrophotometer (Shimadzu AA-7000, Japan) at 248.3 nm wavelength. The slope of the standard curve was used to estimate the iron content in the samples, electronically using wizard software program.

Bioavailability studies: The bioavailability of iron was assessed using coupled in vitro digestion/Caco-2 cell model in the absence or presence of ascorbic acid. Briefly, Fortified flour (2.5g) in the presence and absence of ascorbic acid (1:10 molar ratio) was weighed into 50 mL tubes and suspended in 30 mL of 0.9% saline and the pH was adjusted to 2.8. 2 mL of pepsin (4 g/100 mL in 0.1N HCl) was added and the final volume of all the samples was made to 40 mL with 0.9% NaCl. The tubes were immersed in a shaking water-bath at 37oC for 120 min. At the end of gastric digestion, the pH of the digesta was adjusted to 6.5, supplemented with pancreatin and bile extract (0.2 g & 1.2 g/100mL 0.1 N NaHCO3). The samples were again incubated for 2h. At the end of intestinal digestion, the digesta was boiled for 10 mins in a water bath to inactivate the digestive enzymes followed by feeding the digesta to differentiated Caco-2 cells in triplicates for a period of 4 h. After 4 h, digesta was replaced with fresh MEM and incubation was continued for 20 h. At the end of the incubation the cells were washed, lysed and ferritin content in the cell lysate was analyzed using sandwich ELISA kit (Calbiotech, USA) as per the manufacturer’s instructions. The colour intensity was measured using an ELISA plate reader (BioTek, Powerwave HT-1).

Cellular ferritin induction, was expressed as in terms of ng ferritin/mg protein, is considered as the index of in-vitro iron bioavailability. The ferritin formation of the FeSO4 is taken as the standard reference and is considered as 100%. The percentage of ferritin induction in the Caco-2 cells treated with other elemental iron powders with respect to the cells treated with reference FeSO4 is considered as the Relative Bioavailability (RBV) of the iron powder.

Haemoglobin repletion tests in rats: The relative biological value (RBV) of the three elemental iron powders was determined by a haemoglobin depletion and repletion studies in rats as described previously with minor modifications (AOAC). The weanling male Wistar/Kyoto rats (n=36) were supplied by the National Centre for Laboratory Animal Sciences (NCLAS), India and were housed individually in polypropylene cages with stainless steel wire floors: 45 cm x 16 cm, 7.5 mm mesh, 1 mm wire diameter to prevent coprophagy, in a room maintained at 23°C and 60% humidity, with a 12-h light: dark cycle. Weanling rats (21-day old) were fed with either control (57.37 µg iron/g diet; n=6) or iron deficient diet-AIN-93G (12.14µg/g diet; n=30) for a period of 4 weeks ad libitum and allowed free access to water throughout the experiment. The body weights of rats (every week), diet intakes (every day) were assessed during the entire experiment period. At the end of 30 days, 1 mL blood was drawn from all the rats, hemoglobin levels were estimated to ensure the development of iron deficiency anaemia. The rats were then divided into 5 groups (n=6 in each group) based on their Hb to make mean Hb in each group similar, and repleted with diet fortified with either FeSO4 or different iron powders viz., standard of care Electrolytic Iron Powder (EIP), and the iron powder obtained from Examples 1-3 (Fortification level: 30 mg iron/kg diet), for a period of 20 days. At the end of the repletion period, the rats were fasted overnight, and the blood samples were collected by sinus orbital puncture. Hemoglobin (Hb) was estimated in the blood samples using cyanmethemoglobin method (Figure 5).

Determination of Relative Biological Value (RBV): The relative biological value of the iron
powders were calculated as described previously by Lin JF et al., ‘In vitro and In vivo evaluations of mesoporous iron particles for iron bioavailability’, International journal of molecular sciences, 2019 Jan; 20(21):5291. Hb-Fe was calculated, by assuming the total blood volume of the rat as 6.7% and percentage of iron in the hemoglobin as 0.335%. The following equations were used to calculate the RBV of test and commercial iron powders.

HbFe (mg)=((Body weight (g)×Hb (g/L)×6.7×0.335))/10000

%Hemoglobin Regeneration Efficiency (%HRE)=((HbFe_Final-HbFe_initial))/(Fe_intake (mg))

RBV=((%HRE test group))/((%HRE FeSO4 group))×100

Table 6:
Powder Apparent Density
(g/cc) Tapped Density
(g/cc) Hausner Ratio BET surface area
(m2/g) Dissolution in 0.1N HCl after 30 mins
(%) RBV-absence of AA
(%) RBV-presence of AA
(%) RBV- Rat Hb repletion test
(%)
Example 1 0.75 1.15 1.53 0.862 100 77.30 74.17 83.50
Example 2 0.87 1.39 1.59 0.772 100 81.42 67.34 85.47
Example 3 1.1 1.70 1.54 0.50 100 85.12 75.39 98.20
Electrolytic Iron Powder 2.8 3.9 1.39 0.32 53.35 52.07 46.40 82.16

Table 6 gives the measured relevant iron powder properties vis-a-vis a commercial Electrolytic Iron Powder, which showcases that the iron powders of the present disclosure has distinct physio-chemical properties and a high dissolution & relative bioavailability compared to the standard of care. Further, the effect of an iron-absorption enhancer like ascorbic acid (AS) has a similar effect on bioavailability of iron powders to that of FeSO4.

The heavy metals of Arsenic, Lead and Mercury (<1 ppm) were well below the maximum permissible limits as per Food Chemical Codex for all the powders.

Example 5: Comparative analysis of process parameters
The role of process parameters for the reduction of powdered iron oxide into iron powder is assessed. The experiment was carried out by employing the process protocol of Example 1 and varying the time-period and temperature employed as depicted in Table 7. The total iron content and surface area of the reduced iron powder was assessed and the results are depicted in Table 7. The surface area values measured are for particle sizes below 325 mesh i.e. 45 microns except for the examples 1-3 which are as mentioned in the respective examples.

Table 7:
Temperature Time % Iron Surface Area (m2/g)
650 200 97.6 0.889
240 98.0 0.86
Example 1 280 98.61 0.862
300 98.73 0.85
700 200 97.5 0.8
Example 2 240 98.1 0.772
280 98.3 0.75
300 98.4 0.732
800 200 97.8 0.67
240 98.1 0.58
280 98.3 0.54
Example 3 300 98.8 0.5
320 98.9 0.46
900 200 > 98.5 < 0.4
240
280
300

A higher temperature process product has a higher purity but lower surface area and vice-versa. Thus, for a minimum bed height and gas flow rate, an optimum temperature of about 650°C to about 800°C and time of about 240 minutes to 300 minutes is ideal for the reduction process to be completed to end up with a high metallic iron particles sintered with each other.

Claims:1. Elemental iron powder having metallic iron content of at least about 98%, wherein the surface area of the iron powder is ranging from about 0.5 m2/g to about 1.0 m2/g.

2. The elemental iron powder as claimed in claim 1, wherein average particle size of the iron powder is ranging from about 10 microns to 18 about microns, apparent density of the iron powder is ranging from about 0.75 g/cc to about 1.1 g/cc, tap density of the iron powder is ranging from about 1.15 g/cc to about 1.7 g/cc, and/or Hausner ratio of the iron powder is at least about 1.5.

3. A composition comprising the elemental iron powder as claimed in claim 1 or claim 2.

4. The composition as claimed in claim 3, wherein the composition comprises one or more excipient; and wherein the composition is in a form selected from a group comprising powder, tablet, capsule, liquid, elixir, syrup, suspension and solution or any combination thereof.

5. An iron-fortified food product characterised in that the food product is fortified with the elemental iron powder as claimed in claim 1 or claim 2.

6. A method of producing elemental iron powder as claimed in claim 1 or claim 2, wherein sthe method comprises steps of:
a) reacting iron oxide with a reducing agent at a temperature ranging from about 650°C to about 800°C for about 240 minutes to 300 minutes to obtain reduced iron,
b) cooling the reduced iron, and
c) milling the cooled iron to obtain the elemental iron powder,
wherein the milling is carried out by impact forces, shear forces, cutting forces or a combination thereof.

7. The method as claimed in claim 6, wherein the iron oxide is heated with the reducing agent in a reduction furnace in static bed condition; and wherein the reducing agent is selected from a group comprising hydrogen and cracked ammonia or a combination thereof.

8. The method as claimed in claim 6, wherein the reduced iron is cooled to a temperature ranging from about 20°C to about 40°C under inert atmosphere in presence of nitrogen or argon or a combination thereof.

9. The method as claimed in claim 6 or claim 8, wherein the cooled iron is subjected to crushing prior to the step of milling, to obtain iron particles having a size of up to about 2 mm.

10. The method as claimed in claim 6, wherein the method comprises a step of screening the elemental iron powder having particle size lesser than about 40 microns after milling, wherein the screening is carried out using a mesh.

11. The method as claimed in any of claim 6-10, wherein average particle size of the iron powder is ranging from about 10 microns to 18 about microns, apparent density of the iron powder is ranging from about 0.75 g/cc to about 1.1 g/cc, tap density of the iron powder is ranging from about 1.15 g/cc to about 1.7 g/cc, and/or Hausner ratio of the iron powder is at least about 1.5.

12. A method of preparing an iron-fortified food product, characterised in that the elemental iron powder as claimed in claim 1 or claim 2 is added to a food product.