OA18335A - Iron-fortified edible oil-and-water emulsion. - Google Patents

Abstract

The invention relates to an edible oil-and-water emulsion comprising : 10 - 85 wt% of fat; 5 - 90 wt% of water; 0.4 - 100 μιτιοΙ per ml of water of cationic iron selected from ferric iron (Fe3+), ferrous iron (Fe2+) and combinations thereof; 0 25 μmol per ml of water of divalent cations (M2+) selected from Ca2+, Mg2+, Zn2+, Cu2+ and combinations thereof; 0.5 - 1,000 μιτιοΙ per ml of water of polyphosphate anion selected from pyrophosphate (P2O7 4), triphosphate (P3O105), tetraphosphate (P4O136) and combinations thereof; and 0 -20 wt% of one or more other ingredients; wherein : (4x[P2O7 4]+5x[P3O105]+6x[P4O136]) / (2x[Fe2+ ]+3x[Fe3+]+2x[M2+]) ≥ 1.2; [X] representing the molar concentration of compound X in the edible emulsion, and [M2+] representing the total molar concentration of the divalent cation(s) M2+. These emulsions combine high bioavailability of the iron with excellent product taste and good product stability.

Description

IRON-FORTIFIED EDIBLE OIL-AND-WATER EMULSION

TECHNICAL FIELD OF THE INVENTION

The présent invention relates to iron-fortified edible oil-and-water émulsions that combine improved bioavailability of the iron with excellent taste and good product stability. Examples of edible émulsions encompassed by the invention include spreads, margarine, mayonnaise and dressings.

BACKGROUND OF THE INVENTION

Iron is an essential trace element in animal and human nutrition. It is a component of heme in hemoglobin and of myoglobin, cytochromes as well as of the catalytic région of many enzymes. The main rôle of iron is its participation in the transport, storage and utilization of oxygen.

Iron deficiency (sideropenia or hypoferremia) was and remains a common nutritional problem not only in the developing world but also in the industrialized countries. When loss of iron is not sufficiently compensated by adéquate intake of iron from the diet, a state of iron deficiency develops over time. When this state remains uncorrected, it eventually leads to iron deficiency anémia (IDA). Before iron deficiency develops into IDA, the medical condition of Iron Deficiency without anémia is called Latent Iron Deficiency (LID) or Iron-deficient erythropoiesis (IDE). IDA is a common anémia (low red blood cell or hemoglobin levels). Iron deficiency causes approximately half of ail anémia cases worldwide.

The recommended daily allowance for iron intake is from 10 to 27 mg per day, and is dépendent on âge and gender. Children, women of child-bearing âge, and in particular prégnant women, women who wish to become prégnant and nursing mothers are in the group with higher requirements of iron.

Iron compounds which are used or hâve been studied as iron fortificants in nutritional suppléments and food products include ferrous sulfate, ferrous fumarate, ferrous folate, an iron dextran, ferrie oxyhydroxide dextran, a chitosan dérivative of iron, an oligosaccharide dérivative of iron, ferrous acetyl salicylate, ferrous gluconate, ferrous pyrophosphate, carbonyl iron, ferrie orthophosphate, ferrous glycine sulfate, ferrous chloride, ferrous ammonium citrate, ferrie ammonium citrate, ferrie ammonium tartrate, ferrie phosphate, ferrie potassium tartrate, ferrie albuminate, ferrie cacodylate, ferrie hydroxide, ferrie pyrophosphate, ferrie quinine citrate, ferrie valerate, saccharated iron oxide, iron oxide, ferrie chloride, ferrous iodide, ferrous nitrate, ferrous glycérophosphate, ferrous formate, an amino acid and iron sait, an iron sait of a protein hydrolysate, ferrous lactate, ferrous tartrate, ferrous succinate, ferrous glutamate, ferrous citrate, ferrous pyrophosphate, ferrous choline isocitrate, ferrous carbonate, an iron-sugar-carboxylate chelate, ferrous sucrate malate, ferrous sucrate citrate, ferrous fructate citrate, ferrous sucrate ascorbate, ferrous fructate ascorbate, sodium iron EDTA (NaFeEDTA), and ferrous bisglycinate chelate.

In general, water-soluble iron compounds hâve the highest relative bioavailability ofthe conventional iron sources but frequently cause unacceptable sensory changes or deleterious changes in food quality. Ferrous sulfate is the most commonly used, watersoluble iron fortificant and is found in infant formula, bread and pasta, and iron suppléments. It can also be added to wheat flour when stored for short periods but may provoke fat oxidation and off-flavors in milk, wheat and other cereal flours stored for longer periods. Pestaner et al. hâve stated, Ferrous sulfate is the cheapest, most toxic, and most frequently used iron supplément and has an elemental iron content of approximately 20%. [J. P. Pestaner, K. G. Ishak, F. G. Mullick, J. A. Centeno, Ferrous sulfate toxicity: a review of autopsy findings, Biolog. Trace Element Res 69:191-198, 1999] Ferrous sulfate is very soluble in water and aqueous solutions, dissolves to provide solutions having a strongly acid pH of about 2, and is described as a corrosive agent on related Material Safety Data Sheets.

A more expensive alternative to ferrous sulfate, NaFeEDTA, offers the advantages that it has équivalent bioavailability and prevents iron binding to iron absorption inhibitors, particularly phytate. Further, it does not catalyze fat oxidation in stored wheat flour. However, the EFSA Panel on Food Additives and Nutrient Sources advised in 2010 that the daily intake of EDTA from food should not exceed 1.9 mg/kg bodyweight/day. This maximum severely limits the scope for application of EDTA in products that are consumed by infants and children.

Compounds that are poorly soluble in water but soluble in dilute acid (e.g., ferrous fumarate, ferrous gluconate, ferrous saccharate) offer the advantages that they cause less organoleptic changes and may be selected to hâve a bioavailability that is comparable to that of ferrous sulfate. At présent, ferrous fumarate is widely used to fortify infant cereals, and ferrous saccharate is added to chocolaté drink powders. Ferrous bisglycinate, a more expensive alternative to the other ferrous salts, has exhibited equivocal iron bioavailability, and has a tendency to cause color reactions and catalyze fat oxidation.

Water-insoluble compounds that are poorly soluble in dilute acid are the least well absorbed ofthe iron fortificants. In general, this class of insoluble iron fortificants comprises ferrie iron in a form which précipitâtes from aqueous solutions having a pH above 3.5 (e.g., ferrie phosphate, ferrie pyrophosphate) or fine particles of elemental iron (e.g., colloïdal iron). In general, fortificants in this class offer the significant advantages that they hâve no distinctive taste and hâve lower tendencies to promote fat oxidation, but spécial strategies may be needed to enhance bioavailability to useful ranges.

Finally, protoporphyrin-bound iron (heme-Fe) has been studied both as a dietary supplément and an additive in cereals for infants and children. Heme-Fe offers the advantages that uptake is high and predictable, but its intense color and concems about contamination during its collection from bovine blood, together with technical difficulties in processing, residual contamination removal, and storage, deter broad use.

As a conséquence of its widespread use, both in foods and in dietary suppléments, ferrous sulfate is currently the standard against which the bioavailability of other iron sources is compared. Among the conventional strategies that hâve been used to enhance the availabilities of other iron sources are:

• Particle size réduction: Micronization significantly decreases particle size and enhances uptake in the intestine, through more rapid solubilization and other mechanisms.

• Addition of ascorbate: For over 50 years, it has been recognized that ascorbate significantly enhances iron absorption. The primary activity of ascorbate is believed to be chemical réduction of iron from its ferrie to its ferrous oxidation state, since intestinal absorption of ferrous iron is favored. Further, ferrie iron is reduced at the surface of the intestinal cells by the enzyme ferri-reductase (also known as Dcytb), which in tum requires ascorbate for its function. Finally, ascorbate may also enhance iron availability by preserving its solubility through métal chélation for uptake via the divalent métal transporter DMT-1 and/or through transport ofthe chelate via the ascorbate-transporter.

• Addition of organic acids: Studies hâve shown that non-chelated lactic, citric, malic and tartaric acids effected increases in iron absorption and non-chelated oxalic acid significantly reduced uptake in a rat model of iron availability.

• Addition of amino acids: The effects of amino acids hâve been studied in humans and in rat models. In both humans and rodents, cysteine enhanced iron absorption. Further, in vitro studies in CaCo-2 monolayers hâve shown that both cysteine and (reduced) cysteinyl glycine enhanced iron uptake. A significant benefit of cysteine and related thiols over ascorbate is that the former increased iron solubility at the pH of the intestinal lumen, whereas ascorbate must be combined with iron at pH 2 to reduce and solubilize the métal.

• Encapsulation in lipophilie materials: Application of a surface coating serves the dual purposes of masking adverse sensory changes that are associated with the unencapsulated form and modifying uptake of the encapsulated material. Encapsulation may also prevent degradative interactions between the encapsulated material and its environment during long-term storage. Typical coating materials include hydrogenated oils, maltodextrins, modified cellulosics, and pH-responsive coatings (e.g., poly(meth)acrylates). This strategy for enhancement of iron availability has been employed both to provide iron in dried infant formula and dried infant cereals and in dietary suppléments.

• Combinations of these approaches: To date, the most widely studied of the combination approaches is one in which a micronized iron source has been encapsulated (e.g., Taiyo SunActive.RTM., an iron supplément available from Taiyo International Food Company).

Iron fortification of food products - especially of food products that are frequently consumed - provides an idéal vehicle for reducing the occurrence of iron deficiency in the general populations as well as in spécifie consumer groups. Oil-and-water émulsions such as spreads, margarines, mayonnaise and dressings are examples of food products that may be suitably be used as a vehicle for iron supplémentation.

However, fortification of oil-and-water émulsion with known iron compounds is associated with sîgnificant drawbacks. The use of water-soluble iron compounds has an adverse impact on taste and product stability, especially if the fat component contains appréciable levels of oxidisable (poly)unsaturated fatty acids. Water-insoluble iron compounds hâve the disadvantage that they their bioavailability is relatively low and that they hâve a tendency to form a sédiment.

US 2009/0061068 describes an iron-containing additive in the form of iron containing nanoparticles having a particle size of 5 to 1,000 nanometer, wherein the nanoparticles are stabilised by means of a biopolymer. The US application mentions application of the additive in beverages, (dry) soups, fat spreads, (yoghurt or protein) drinks, dressings or cereal products like bread. Example 3 describes the préparation of such an additive by separately preparing a solution of sodium pyrophosphate decahydrate and biopolymer in demineralized water and solution of ferrous sulfate heptahydrate in demineralized water. Next, the iron (II) solution was added to the pyrophosphate-biopolymer solution with vigorous stirring. The reaction self-terminated after formation of iron (II) pyrophosphate nanoparticles. The resulting reaction mixture was subjected to solidliquid séparation by centrifugation, to concentration, or to drying.

US 2009/0023686 describes a process for preparing a water-soluble solid ferrie pyrophosphate citrate chelate composition comprising:

• combining a citrate ion source, a pyrophosphate ion source, and a ferrie ion source in water to form a solution;

• adding an organic solvent in a volume sufficient to precipitate a solid ferrie pyrophosphate citrate chelate composition from the resulting solution; and • isolating the solid ferrie pyrophosphate citrate chelate composition, said chelate composition having 2% or less phosphate by weight.

These chelate compositions are expected to exhibit advantageous biocompatibility as compared to conventîonal ferrie pyrophosphates, ferrie salts, ferrie polysaccharide complexes and ferrous salts.

US 2013/0330459 describes the préparation of an aqueous soluble ferrie pyrophosphate concentrate comprising the steps of:

a) adding 0.1 to 5 weight/volume % ferrie pyrophosphate to water,

b) adding 0.15 to 50 weight/volume % citrate sait to the dispersion from (a),

c) heating the resulting solution from (b) until complété dissolution of ferrie pyrophosphate.

The concentrate so obtained can be used to supplément beverages with soluble and bio-available iron in the form of ferrie pyrophosphate.

SUMMARY OF THE INVENTION .

The inventors hâve discovered a way to achieve iron-fortification of edible oil-and-water émulsions that combines high bioavailability of the iron with excellent product taste and good product stability. More particularly, the inventors hâve found that this goal can be achieved by incorporating on the one hand cationic iron and on the other hand an excess amount of polyphosphate anions. Here an excess amount of polyphosphate anions means that the absolute value of the total négative charge contributed by the (fully deprotonated) polyphosphate anions is significantly higher than the total positive charge contributed by the cationic iron and the following divalent cations: Ca²⁺, Mg²⁺, Zn²⁺, Cu²⁺.

Accordingly, one aspect of the invention relates to an edible oil-and-water émulsion comprising:

• 10 - 85 wt% of fat;

• 5-90 wt% of water;

• 0.4 -100 pmol per ml of water of cationic iron selected from ferrie iron (Fe³⁺), ferrous iron (Fe²⁺) and combinations thereof;

• 0-25 pmol per ml of water of divalent cations (M²⁺) selected from Ca²⁺, Mg²⁺, Zn²⁺, Cu²⁺ and combinations thereof;

• 0.5-1,000 pmol per ml of water of polyphosphate anion selected from pyrophosphate (P2O7⁴·), triphosphate (P3O10⁵·), tetraphosphate (P4O13⁶·) and combinations thereof ; and • 0 -20 wt% of one or more other ingrédients;

wherein: (4x[P₂0₇ ⁴1+5x[P301o⁵1+6x[P4013⁶1) / (2x[Fe²⁺]+3x[Fe³⁺]+2x[M²⁺J) £ 1.2;

[X] representing the molar concentration of compound X in the edible émulsion, and [M²⁺] representing the total molar concentration of the divalent cation(s) M²⁺.

Although the inventors do not wish to be bound by theory, it is believed that in the aqueous phase of the présent oil-and-water émulsion the cationic iron is présent as a polyphosphate complex that includes both strongly coordinated and loosely associated polyphosphate anions. The loosely associated polyphosphate anions are believed to aid dissolution and absorption ofthe iron. In orderto produce iron-phosphate complexes containing loosely associated polyphosphates, polyphosphate anions should be présent in the émulsion in an excess amount. Such an excess amount is not achieved by dispersing, for instance, iron pyrophosphate (Fe^(lll)4P6O₂i) in water. In the latter case, the ratio 4x[P20z^4_]/3x[Fe³⁺] equals 1.0.

In case the émulsion contains Ca²⁺, Mg²⁺, Zn²⁺ and/or Cu²⁺ cations (divalent cations), more polyphosphate anion is required to form the desired iron-polyphosphate complex, probably because a fraction of the polyphosphate cations is competitively bound by these divalent cations.

Rao et al. (“Studies on the effect ofinorganic polyphosphates on dietary ionisable iron and the solubility of other minerais in vitro”; Nutrition Reports International; 1984, Vol.

29, no.4, p. 941-948) hâve reported that sodium tripolyphosphate, sodium trimetaphosphate and tetra sodium pyrophosphate when added to raw and cooked foods at 1% could increase dietary ionisable iron significantly. The authors investigated the effect of polyphosphates on the ionisable content of wheat flour, bengalgram flour, baked chapathi and cooked rice.

The iron-fortified of the présent invention offers the additional advantage that it is very easy to manufacture. Thus, the invention further provides a process of preparing the aforementioned edible émulsion, said process comprising addition of (i) an iron sait selected from ferrous sulphate, ferrous gluconate, ferrous lactate, ferrous bisglycinate, ferrous fumerate, ferrie orthophosphate, ferrie pyrophosphate, ferrous tartrate, ferrous succinate, ferrous saccharate, ferrous orthophosphate and combinations thereof and (ii) a polyphosphate sait of an alkali métal, said polyphosphate being selected from pyrophosphate, triphosphate, tetraphosphate and combinations thereof.

DETAILED DESCRIPTION OF THE INVENTION

A first aspect of the présent invention relates to an edible oil-and-water émulsion comprising:

• 10 - 85 wt% of fat;

• 5-90 wt% of water;

• 0.4 -100 pmol per ml of water of cationic iron selected from ferrie iron (Fe³⁺), ferrous iron (Fe²⁺) and combinations thereof;

• 0-25 pmol per ml of water of divalent cations (M²⁺) selected from Ca²⁺, Mg²⁺, Zn²⁺, Cu²⁺ and combinations thereof;

• · 0.5-1,000 pmol per ml of water of polyphosphate anion selected from pyrophosphate (P2O7⁴·), triphosphate (P3O10⁵·), tetraphosphate (P4O13⁶·) and combinations thereof; and • 0 -20 wt% of one or more other ingrédients;

wherein: (4x[P₂O₇ ⁴-]+5x[P₃O₁₀ ⁵1+6x[P4Oi3⁶l) / (2x[Fe²⁺]+3x[Fe³⁺]+2x[M²⁺]) £ 1.2;

[X] representing the molar concentration of compound X in the edible émulsion and [M²⁺] representing the total molar concentration of the divalent cation(s) M²⁺.

The term “fat” as used herein, unless indicated otherwise, refers to a lipid material that may be solid, semi-solid or liquid at room température (20°C).

The term “oil-and-water émulsion” as used herein refers to a composition comprising a fat phase and an aqueous phase. The oil-and-water émulsion may be water-continuous and/or oil-continuous.

The term “polyphosphate sait” as used herein encompasses anhydrous polyphosphate salts as well as hydrated polyphosphate salts.

In accordance with one embodiment, the edible oil-and-water émulsion ofthe présent invention is an oil-in-water émulsion. Examples of edible oil-in-water émulsions that are encompassed by the présent invention include mayonnaise and dressings. The fat contained in the oil-in-water émulsion preferably is liquid at 20°C. Typically, the fat content of the oil-in-water émulsion is in the range of 5-85 wt.%, more preferably in the range of 10-83 wt.% and most preferably in the range of 30-81 wt.%.

The aqueous phase of the oil-in-water émulsion preferably has a pH in the range of 2.0 to 6.0, more preferably in the range of 2.5 to 5.5 and most preferably in the range of 3.0 to 5.0.

In accordance with another embodiment, the edible oil-and-water émulsion is a waterin-oil émulsion. Examples of water-in-oil émulsion encompassed by the présent invention include spreads and margarine, including liquid margarine. The fat contained in the water-in-oil émulsion preferably has a solid fat content of at least 10% at 20°C. The solid fat content of fat at 20°C can suitably be determined by puise NMR spectroscopy (ISO method 8292-1:2008). The fat content of the water-in-oil émulsion typically is in the range of 18-85 wt.%, more preferably in the range of 28-83 wt.% and most preferably in the range of 35-81 wt.%.

The aqueous phase ofthe water-in-oil émulsion preferably has a pH in the range of 2.5 to 8.0, more preferably in the range of 3.0 to 7.0 and most preferably in the range of 4.0 to 6.0.

The fat contained in the présent émulsion preferably is selected from triglycérides, diglycerides, monoglycerides, phospholipids and combinations thereof. Typically, said fat contains at least 50 wt.%, more preferably at least 80 wt.% and most preferably at least 90 wt.% triglycérides.

According to a preferred embodiment, the présent émulsion contains 0.8 - 50 pmol cationic iron per ml of water. Even more preferably, the émulsion contains 1.4-30 pmol per ml of water, most preferably 2-20 pmol per ml of water.

Preferably, the ratio (4x[P₂0₇ ⁴-]+5x[P30io⁵1+6x[P₄Oi3⁶1) / (2x[Fe²⁺]+3x[Fe³⁺]+2x[M²⁺J is at least 1.3. Even more preferably, this ratio is at least 1.5, more preferably at least 2.0, even more preferably at least 3.0 and most preferably at least 4.0

In one embodiment of the présent invention the émulsion contains at least 0.4 pmol ferrie iron per ml of water. Even more preferably the ferrie iron content is at least 0.8 pmol per ml of water, most preferably at least 2 pmol per ml of water. In case the présent émulsion contains such a significant amount of ferrie iron the concentrations of ferrie iron and polyphosphate anions preferably meet the following condition: (4χ[Ρ2θ7⁴1+5χ[Ρ3θ1ο⁵Ί+6χ[Ρ40₁3⁶Ί) / (3x[Fe³⁺]+2x[M²⁺]) à 1.3.

Even more preferably, the latter ratio is at least 1.5, more preferably at least 2.0, even more preferably at least 3.0 and most preferably at least 4.0.

In accordance with another embodiment, the émulsion contains at least 0.4 pmol ferrous iron pergram of water. Even more preferably the ferrous iron content is at least 0.8 pmol per ml of water, most preferably at least 2 pmol per ml of water. The émulsion that contains a significant amount of ferrous iron preferably contains ferrous iron and polyphosphate anions in concentration that meet the following condition: (4x[P₂O₇ ⁴1+5x[P3O10⁵1+6x[P4O13⁶1)/(2x[Fe²⁺]+2x[M²⁺]) £ 1.3.

Even more preferably, the latter ratio is at least 1.5, more preferably at least 2.0, even more preferably at least 3.0 and most preferably at least 4.0.

The polyphosphate anion is preferably contained in the émulsion in a concentration of 1 - 500 pmol per ml of water, more preferably of 2 - 350 pmol per ml of water and most preferably of 4 - 250 pmol per ml of water.

The concentration of divalent cations (M²⁺) in the présent émulsion preferably does not exceed 20 pmol per ml of water. More preferably, the cationic calcium content does not exceed 15 μηηοΙ per ml of water, most preferably it does not exceed 10 pmol per ml of water.

The cationic calcium content of the présent émulsion preferably does not exceed 20 pmol per ml of water. More preferably, the cationic calcium content does not exceed 10 pmol per ml of water, most preferably it does not exceed 5 pmol per ml of water.

The molar ratio of M²⁺ to cationic iron in the émulsion typically does not exceed 1:1. More preferably said molar ratio does not exceed 1:2, even more preferably ratio does not exceed 1:3 and most preferably it does not exceed 1:4.

Besides the fat, water, cationic iron, optional cationic calcium and polyphosphate anion, the présent émulsion can contain up to 20 wt% of one or more other ingrédients. Examples of other ingrédients that can be présent in the émulsion include biopolymers (e.g. proteins and/or polysaccharides), carbohydrates, acids, minerais, vitamins, colourings, flavourings, preservatives, anti-oxidants and emulsifiers (other than monoglycerides, diglycerides and phospholipids). Preferably the émulsion contains not more than 14 wt.%, more preferably not more than 10 wt.% ofthe one or more other ingrédients.

The présent émulsion may suitably be prepared by adding ferrous iron in the form of a water soluble sait and by adding a polyphosphate sait that is not an iron sait. Examples of ferrous salts that may be employed include ferrous sulphate, ferrous gluconate, ferrous lactate, ferrous bisglycinate, ferrous fumerate, ferrous tartrate, ferrous succinate and ferrous saccharate. Accordingly, in a preferred embodiment, the émulsion contains one or more anions selected from sulphate, gluconate, lactate, bisglycinate, fumerate, tartrate, succinate, saccharate and combinations thereof, and at least 0.4 pmol per ml of water of ferrous iron. According to a particularly preferred embodiment, the concentrations of ferrous iron and the latter anions meet the following équation:

0.5 £ ([sulphate]+0.5x[gluconate]+0.5x[lactate]+[bisglycinate]+[fumerate]+[tartrate]+ [succinate]+0.5x[saccharate])/[Fe²⁺] < 1.1.

In a preferred embodiment, the émulsion contains a significant amount of pyrophosphate and/or triphosphate relative to the amount of cationic iron and cationic calcium. Accordingly it is preferred that the polyphosphate and cationic iron concentrations meet the following condition: (4χ[Ρ2θ₇ ⁴’]+5χ[Ρ3θιο⁵1) / (2x[Fe²⁺]+3x[Fe³⁺]+2x[M²⁺]) s 1.2. More preferably, the latter concentration ratio exceeds 1.5, even more preferably the ratio exceeds 2 and most preferably it exceeds

4.

According to a particularly preferred embodiment the émulsion contains a significant amount of pyrophosphate relative to the amount of cationic iron and cationic calcium. Thus, it is preferred that the pyrophosphate and cationic iron concentrations meet the following condition: 4x[P2O₇ ⁴1 / (2x[Fe²⁺]+3x[Fe³⁺]+2x[M²⁺]) £ 1.2.

The émulsion of the présent invention preferably comprises not more than a very small amount of EDTA, e.g. less than 1 pmol EDTA per ml of water. More preferably, the émulsion contains not more than 0.2 pmol EDTA per ml of water, most preferably, the émulsion does not contain EDTA.

Another aspect ofthe présent invention relates to the use ofthe edible oil-and-water émulsion as defined herein in the treatment or prévention of iron deficiency.

A further aspect of the invention relates to a process of preparing the edible oil-andwater émulsion as defined herein before, said process comprising addition of (i) an iron sait selected from ferrous sulphate, ferrous gluconate, ferrous lactate, ferrous bisglycinate, ferrous fumerate, ferrie orthophosphate, ferrie pyrophosphate, ferrous tartrate, ferrous succinate, ferrous saccharate, ferrous orthophosphate and combinations thereof; and (ii) a polyphosphate sait of an alkali métal, said polyphosphate sait being selected from pyrophosphate sait, triphosphate sait, tetraphosphate sait and combinations thereof.

The polyphosphate sait employed in the présent process is preferably selected from sodium pyrophosphate, sodium triphosphate, potassium pyrophosphate, potassium triphosphate and combinations thereof.

According to a particularly preferred embodiment, the polyphosphate sait used is a pyrophosphate sait. Even more preferably, polyphosphate sait is selected from tetrasodium pyrophosphate (Na4P2O7), tetrapotassium pyrophosphate (K4P2O7), disodium pyrophosphate (NaahbPaCM, dipotassium pyrophosphate (K2H2P2O7) and combinations thereof.

The iron sait employed in the présent process is preferably selected from ferrie pyrophosphate, ferrous sulphate and combinations thereof. More preferably, the iron sait is ferrie pyrophosphate.

The ferrie pyrophosphate is preferably added in the form of a powder having a weight averaged mean particle size of less than 25 pm, more preferably of less than 15 pm and most preferably in the range of 0.1-10 pm.

Yet another aspect of the invention relates to the use of a water-soluble pyrophosphate to increase bioavailability of ferrie or ferrous iron in oil-and-water émulsions. According to a particularly preferred embodiment, this use comprises separate addition of the water-soluble pyrophosphate and of an iron sait selected from ferrie sait and ferrous sait.

The invention is further illustrated by the following non-limiting examples.

EXAMPLES

Example 1

Bioaccessibility of ionic iron from two different kitchen margarines was assessed using an in vitro assay.

The term ' bioaccessible iron’ refers to the fraction of an iron dose which is - after dissolution and digestion steps - in the ionic form and capable to pass a low molecular weight (MW) cut-off filter (also referred to as dialyzable iron).

A suspension containîng 37.5 mmol ferrie iron was prepared by dispersing micronized iron pyrophosphate (FePP) into milli-Q water. In addition, a pyrophosphate solution was prepared by dissolving sodium pyrophosphate (NaPP) in milli-Q water. The formulations of these stock solutions are shown in Table 1.

Table 1

	FePP suspension	NaPP solution
Micronised iron pyrophosphate (FePP)1	8.4 g
Sodium pyrophosphate (NaPP)2		10g
milli Q- water	To 1 litre	To 1 litre
1 Ρβ4(Ρ2θ7)3·ΧΗ2Ο (Fe conten	24.9 wt.%), ex Dr. Paul Lohmann

Na4P2O7, ex BK Guilini

In order to assess the influence of added pyrophosphate on bioaccessibility of iron from a kitchen margarine fortified with FePP, the mixtures shown in Table 2 were tested in an in vitro bioaccessibility assay.

Table 2

Sample	Margarine 1	FePP suspension	NaPP solution	Milli-Q water
1	10 ml	1 ml	—	69 ml
2	10 ml	1 ml	1 ml	68 ml

Commercially available kitchen margarine with a fat content of 56% (Becel keuken light, the Netherlands)

Bioaccessibility was assessed using the following procedure:

Ail glassware was incubated ovemight in 10 % (v/v) HNO3. On the day ofthe experiment ali glassware was washed 5 times with milli-Q water to remove HNO3. Margarine samples were transferred into 100 ml dissolution vessels in the dissolution apparatus (type II, VanKel VK700) and milli-Q water, FePP suspension and NaPP solution were added (see Table 2). The pH in the vessel was adjusted to 2.0 with HCl. Subsequently, 10 ml pepsin solution (0.5 mg/mL in 0.1 M HCl) was added to each vessel, yielding a 90 ml dispersion of margarine in simulated gastric fluid at pH 2.0. After 60 minutes incubation at 37 °C with mixing at 100 rpm, samples were taken for total iron détermination and for simulation of the intestinal phase in an Erlenmeyer flask.

Forthe simulation ofthe intestinal phase, a dialysis membrane (Spectra/Por7 MWCO 8000) filled with a water solution of NaHCO₃ was placed in the Erlenmeyer flask. The amount of sodium bicarbonate présent in the dialysis membrane was sufficient to adjust the simulated digestion to pH 7.5. After 30 minutes incubation in a water bath at 37 °C and continuous shaking (100 rpm) to raise the pH gradually, a mix of pancreatin (0.4 mg/mL) and bile acids solution (1.25 mg/mL) was added to the flask. The flask was further incubated with the dialysis membrane for another 2 hours in the same water bath at 37 °C with continuous shaking (100 rpm). Hereafter, the dialysis membrane was removed and the content of the membrane (dialysate) was stored in aliquots for détermination of ionic dialyzable iron and iron uptake experiments.

Bioaccessibility of iron is calculated by means of the following :

(Dialyzable Ionie iron / 0.4)

Total Fe *100% wherein:

• 0.4 represents the dilution factor that compensâtes for the dilution that occurred when going from gastric phase to intestinal phase • dialysable ionic iron is the ionic iron (mg/kg) présent in the dialysate • total Fe is the total iron concentration (mg/kg) after gastric simulation.

The results from the bioaccessibility test are shown in Table 3

Table 3

	Bioaccessible ionic iron (%)	S.D.
Sample 1	11.5	2.3
Sample 2	13.0	2.5

Example 2

Bioaccessibility of ionic iron from two different mayonnaises was assessed using an in vitro assay.

In order to assess the influence of added pyrophosphate on bioaccessibility of iron from a mayonnaise fortified with FePP, the mixtures shown in Table 4 were tested in the in vitro bioaccessibility assay described in Example 1.

Table 4

Sample	Mayonnaise 1	FePP suspension2	NaPP solution*	Milli-Q water
1	15 ml	1 ml	—	64 ml
2	15 ml	1 ml	1 ml	63 ml

¹ CommerciaÎÎyavaiÎabÎemayonnaise with a fat content of 25% (Hellmann’s light, UK) ² Same as in Example 1

The results from the bioaccessibility test are shown in Table 5

Table 5

	Bioaccessible ionic iron (%)	S.D.
Sample 1	8.6	0.6
Sample 2	17.3	0.2

In addition, samples 1 and 2 were subjected to an ln-vitro iron uptake test, using human colonie adenoma carcinoma (Caco-2) cells, to détermine bioavailable iron.

Ίη vitro bioavailable iron’ refers the fraction of an iron dose which is - after dissolution and digestion steps - in the ionic form and capable to enter cells to trigger a response (ferritin formation).

The following procedure was followed to détermine In vitro bioavailable iron’.

Caco-2 cells were seeded in 12-wells plates (Brand) at a density of 2*10⁵ cells per well. The cells were grown in Dulbecco’s modified Eagle's medium with 4.5 g/L glucose and L-glutamine (Bio-Whittaker), supplemented with 20% (v/v) heat-inactivated fêtai bovine sérum (Gibco), 1 % (v/v) penicillin/streptomycin (Bio-Whittaker) and 1% (v/v) nonessential amino acids (Gibco). The cells were maintained at 37°C in an incubator with a

5% CO2 / 95% air atmosphère at constant humidity; the medium was changed every 23 days. The cells were cultured for 21 days, so that they can form a monolayer of differentiated cells that resembles that of the intestinal mucosa. At this point, cells were used for iron uptake experiments.

On the day of experiment, the dialysate samples were thawed and diluted (3 ml dialysate with 0.6 ml milli-Q water and 0.4 ml 10 times concentrated Minimum Essential Medium+ (MEM+)). MEM+ concentrated media was prepared by mixing PIPES (100 mmol/L), 5 % penicillin/streptomycin solution (Bio-Whittaker), hydrocortisone (20 pg/L), insulin (50 mg/L), sélénium (50 pg/L), triiodotrionine (340 pg/L), epidermal growth factor (50 mg/L), 10 % non essential amino acids (Bio-Whittaker), NaHCO3 (22 mg/L), NaOH (for pH correction to pH 7.0), powder MEM (Gibco) and milli-Q water to a final volume of 100 mL. The concentrated MEM+ as well as the diluted samples was stérile filtered (0.22 pm). As positive control, a sample was prepared with 5 pM FeSO4 in MEM+. The négative control was plain 1 x MEM+. After washing the cells twice with 1 mL of 1 x MEM+, 1 mL of the diluted samples and control was appiied.

Exactly 48 hours after the start of the incubation of the dialysates and the control in the incubator, the cell monolayers were harvested for ferritin and protein measurements. For this, the medium covering the cells was removed carefully and the cells were washed twice with 1 mL “rinse” solution (containing NaCI (140 mM), KCI (5 mM) and PIPES (10 mM) adjusted to pH 7.0 with NaOH (4 M); osmolarity 0.301 Osmol/kg). The rinse” solution was then aspirated and 250 pL of ice-cold milli-Q water were added. The plate was wrapped in parafilm and sonicated on ice in a water bath at 4°C for 15 minutes. After sonication the cells were scraped and collected in vials. The samples were stored at -20°C until further use.

Ferritin was measured using a commercial ELISA kit (H-ferritin (human) ELISA kit, 96 assays, Abnova, Taipei city, Taiwan, Catalogue number: KA0211) according to the manufacturées description (version 4). Wavelengths 620, 450 and 405 nm were read according to the Radim protocol (KP33IW -ferritina iema well - M108 - Rev08 10/2007).

Total protein was measured with the Bradford assay (Bradford reagent, Sigma-Aldrich) using immunoglobulin G (0 - 0.7 mg/ml, Bio-Rad Protein standard 1 (IgG)) as standard. Cell lysâtes were 10 times diluted prior analysis and 250 pi Bradford reagent was added to 20 μΙ diluted sample/standard. Assay was performed at 595 nm.

Caco-2 cell iron uptake results were expressed as ng of ferritin per mg of total protein. The results of this iron uptake test are summarised in Table 6

Table 6

	Mean (ng ferritin / mg protein)	S.D.
Sample 1	83.7	5	n = 2
Sample 2	124.4	19	n = 2
Sample 1	102.5	33	n = 3
Sample 2	137.4	26	n = 3

Example 3

Analyses were conducted to détermine the stoichiometry of (Fe³⁺)pyrophosphates complexes in aqueous environment.

Materials and methods:

1D ³¹P (¹H-decoupled) NMR spectra were recorded with a ZGIG puise sequence on a Bruker Avance DRX 600 NMR spectrometer, equipped with a 10-mm broadband probe. The probe was tuned to detect ³¹P résonances at 242.94 MHz (¹H 600.13 MHz). The internai probe température was set to 303 K. 128 scans were collected in 32K data points with a relaxation delay of 15 seconds and an acquisition time of 0.85 seconds. The data were processed in TOPSPIN software version 3.1 pl 5 (Bruker BioSpin GmbH, Rheinstetten, Germany). An exponential window function was applied to the free induction decay (FID) with a line-broadening factor of 1 Hz prior to the Fourier transformation. Manual phase correction and baseline correction were applied to ail spectra.

Sample préparation:

Two titration experiments with NaPP were performed at pH 2.5: one with a constant amount of FePP (66 mg Fe/L) and one without Fe (blank). Ail solutions were subsequently taken to neutral pH where some précipitation occurred, in particular at low NaPP équivalents. 800 pL of the prepared solution was added to 3200 pL D₂O. This mixture was then stirred for 10 minutes. 3 mL of this mixture was transferred to a 10mm NMRtube.

Measurements & Results:

For both titrations, twelve different NaPP concentrations were measured, making for a total of 24 samples. Ail 24 experiments showed a singlet in the ³¹P-NMR spectrum, with only minor pH-induced chemical shifts. This singlet was assigned to pyrophosphate (PP). Throughout the spectra, these signais were integrated and normalized. The blank titration experiment showed slightly higher PP-amounts than the FePP-experiment: this is expected because an FePP-complex is formed, which broadens the PP-signal beyond détection due to its paramagnetic effect.

The différence between the blank and FePP experiments should be an indication as to the amount of PP that is tightly bound in complex with Fe. The measured différences are summarized in Table 7. It can be seen that the différence approaches 3 équivalents. To check whether the observed différences (between blank and FePP titrations) can indeed be attributed to spectral perturbation by paramagnetic iron, ICP-MS analysis was performed to check the amounts of Fe in the System. Also these results are depicted in Table 7.

Table 7

Eq. PP μΜ	Différence (Equivalent Fe)
31P NMR	ICP-MS mg/kg
0.3	0.22	2.4
1.5	0.53	32.2
2.7	0.84	42
3.9	1.15	47.5
5	1.43	50.7
6.3	1.92	53.2
7.5	2.10	58.6
9.9	2.14	61.2
12.2	2.18	61.4
18.2	2.28	60.6
24.2	2.38	61.3
34.3	2.55	60.3

It can be seen that Fe is indeed présent in the system, reaching its weighed in value (61 mg Fe/kg) at 6-8 équivalents of NaPP. At low NaPP équivalents not ail added iron is recovered, but at higher values ali added iron is dissolved. This confirms our interprétation of the différences between titration of the blank and FePP solution.

Conclusions

The ³¹P-NMR analysis ofthe two titration experiments shows that approximately 3 pyrophosphate molécules are associated to Fe³⁺ on a timescale long enough to extinguish the PP-signal in the ³¹P-NMR spectrum. Even though maximum solubility of Fe³⁺ is achieved around 6-8 NaPP équivalents, this effect cannot be solely explained due to complexation of Fe³⁺ with PP-ligands. Ionie strength possibly adds to increased solubility.

Claims (14)

1. Claims

   1. An edible oil-and-water émulsion comprising:

   • 10 - 85 wt% of fat;

   • 5-90 wt% of water;

   • 0.4-100 pmol per ml of water of cationic iron selected from ferrie iron (Fe³⁺), ferrous iron (Fe²⁺) and combinations thereof;

   • 0-25 pmol per ml of water of divalent cations (M²⁺) selected from Ca²⁺, Mg²⁺, Zn²⁺, Cu²⁺ and combinations thereof;

   • 0.5-1,000 pmol per ml of water of polyphosphate anion selected from pyrophosphate (P2O7⁴·), triphosphate (P3O-10⁵·), tetraphosphate (P4O13⁶·) and combinations thereof; and • 0 -20 wt% of one or more other ingrédients;

   wherein: (4χ[Ρ2θ7⁴1+5χ[Ρ₃0₁ο⁵1+6χ[Ρ4θΐ3⁶1) / (2x[Fe²⁺]+3x[Fe³⁺]+2[M²⁺]) £ 1.2;

   [X] representing the molar concentration of compound X in the edible émulsion, and [M²⁺] representing the total molarconcentration ofthe divalent cation(s) M²⁺.
2. 2. Edible émulsion according to claim 1, wherein the émulsion contains at least 0.4 pmol ferrie iron per ml of water.
3. 3. Edible émulsion according to claim 1, wherein the émulsion contains at least 0.4 pmol ferrous iron per ml of water.
4. 4. Edible émulsion according to claim 3, wherein the émulsion contains one or more anions selected from sulphate, gluconate, lactate, bisglycinate, fumerate, tartrate, succinate, saccharate, and combinations thereof; wherein:

   0.5 s ([sulphate]+0.5x[gluconate]+0.5x[lactate]+[bisglycinate]+[fumerate]+[tartrate]+ [succinate]+0.5x[saccharate]) / [Fe²⁺] £1.1.
5. 5. Edible émulsion according to any one of the preceding claims, wherein (4x[P2O/** ]+5χ[Ρ₃Ο₁₀ ⁵Ί) / (2x[Fe²⁺]+3x[Fe³⁺]+2[M²⁺]) £ 1.2.
6. 6. Edible émulsion according to claim 5, wherein 4x[P₂O₇ ⁴·] / (2x[Fe²⁺]+3x[Fe³⁺]+2[M²⁺J) £1.2.
7. 7. Edible émulsion according to any one of the preceding claims, wherein the molar ratio of M²⁺ to cationic iron does not exceed 1:1.
8. 8. Edible émulsion according to any one of the preceding claims, wherein the émulsion comprises a fat phase and an aqueous phase, said aqueous phase having a pH in the range of 2.5 to 6.0.
9. 9. Edible émulsion according to any one of the preceding claims, for use in the treatment or prévention of iron deficiency in humans.
10. 10. A process of preparing an edible émulsion according to any one ofthe preceding claims, said process comprising addition of (i) an iron sait selected from ferrous sulphate, ferrous gluconate, ferrous lactate, ferrous bisglycinate, ferrous fumerate, ferrie orthophosphate, ferrie pyrophosphate, ferrous tartrate, ferrous succinate, ferrous saccharate, ferrous orthophosphate and combinations thereof and (ii) a polyphosphate sait of an alkali métal, said phosphate being selected from pyrophosphate, triphosphate, tetraphosphate and combinations thereof.
11. 11. Process according to claim 10, wherein the polyphosphate sait is selected from sodium pyrophosphate, sodium triphosphate, potassium pyrophosphate, potassium triphosphate and combinations thereof.
12. 12. Process according to claim 10 or 11, wherein the polyphosphate sait is a pyrophosphate sait.
13. 13. Process according to any one of daims 10-12, wherein the iron sait is selected from ferrie pyrophosphate, ferrous sulphate and combinations thereof.
14. 14. Process according to claim 13, wherein the iron sait is ferrie pyrophosphate.