WO2024261204A1

WO2024261204A1 - Iron-containing green plant material concentrate

Info

Publication number: WO2024261204A1
Application number: PCT/EP2024/067369
Authority: WO
Inventors: Greta CANELLI; Edwin Alberto HABEYCH NARVAEZ; Martin Michel; Laurent Sagalowicz; Eric Gabriel Marchal; Lisa Marcela LAMOTHE
Original assignee: Societe des Produits Nestle SA; Nestle SA
Current assignee: Societe des Produits Nestle SA; Nestle SA
Priority date: 2023-06-22
Filing date: 2024-06-21
Publication date: 2024-12-26
Anticipated expiration: 2025-12-22

Abstract

A process for preparing an iron-containing green plant material concentrate is disclosed. The process comprises the steps of suspending a green plant in an aqueous liquid to form a green plant material suspension. The green plant material suspension is then blended, processed through physical mean, and optionally dried. Such an iron-containing green plant material concentrate is also disclosed. In addition, food product, beverage, food supplement, cosmetic composition or pharmaceutical composition comprising such an iron-containing green plant material concentrate and a method for fortifying a food product or beverage with iron are also disclosed.

Description

IRON-CONTAINING GREEN PLANT MATERIAL CONCENTRATE TECHNICAL FIELD The present invention relates generally to the field of iron-containing ingredients derived from plant. For example, the present invention relates to process for preparing an iron-containing green plant material concentrate and to iron-containing green plant material concentrate thereof. It also relates to food product, beverage, food supplement, cosmetic composition or pharmaceutical composition comprising such an iron-containing green plant material concentrate. It also relates to a method for fortifying a food product or beverage with iron involving the use of such an iron-containing green plant material concentrate. BACKGROUND OF THE INVENTION According to WHO, iron deficiency is the most common nutritional deficiency worldwide. Nearly 30% of the world’s population is anaemic, half of which due to iron deficiency (Gupta et al., 2020). However, iron fortification is not straightforward, and requires consideration in selecting the right source and mixing procedures to avoid sensory problems, such as metallic taste and discoloration. Commercially available solutions mainly correspond to inorganic iron salts. These inorganic solutions entail many drawbacks. First, they are not natural as they are achieved through chemical reactions/extracted from mines. Moreover, iron salts have lower consumer acceptance compared to real food ingredients delivering the same micronutrients. Finally, inorganic iron salts are often poorly absorbed because they are likely to form complexes with low solubility in the mild basic environment of the upper intestine. Alternative solutions to inorganic iron salts are organic iron compounds coming from animal source, such as haemoglobin, myoglobin or forms of cytochromes. These organic iron compounds coming from animal source are better absorbed in human body than their inorganic counterparts. However, in view of their origin, they are not suitable for vegetarian/vegan diets. Other alternative solutions to inorganic iron salts are organic iron compounds coming from plant source. In plants, iron is present as iron-protoporphyrin in the cytochrome b or as phyto-ferritin. However, organic iron compounds from plant source still entail some drawbacks. First, plants comprise anti-nutritional factors such as oxalic acid and phytic acid which may chelate iron. The iron chelation induced by these antinutritional factors is responsible for the low bioavailability of iron from plant sources when ingested in the human body. In addition, organic iron compounds from plant source may impart sensory defects, such as unpleasant off-notes, when used in food products, food supplements or beverages. For example, an iron solution on the market corresponds to curry leaves extract. However, the use of this curry leaves extract in food products, food supplements or beverages is limited due its strong metallic off-taste. It would therefore be desirable to provide an ingredient that is a substantial source of iron and that may be used to fortify food products and beverages or to prepare food supplements, cosmetic or pharmaceutical compositions that deliver iron. It is desirable that this ingredient is natural, is suitable for vegetarian/vegan diet, has limited content of antinutritional factors decreasing or preventing iron absorption, has satisfactory bioaccessibility properties and has good sensory properties, in particular limited metallic off- taste. Any reference to prior art documents in this specification is not to be considered an admission that such prior art is widely known or forms part of the common general knowledge in the field. SUMMARY OF THE INVENTION The object of the present invention is to improve the state of the art, and in particular to provide process, iron-containing green plant material concentrates, food products, beverages, food supplements, cosmetic compositions, pharmaceutical compositions and method for fortifying a food product or a beverage with iron that overcome the problems of the prior art and addresses the needs described above, or at least to provide a useful alternative. The inventors were surprised to see that the object of the present invention could be achieved by the subject matter of the independent claims. The dependent claims further develop the idea of the present invention. Accordingly, a first aspect of the invention proposes a process for preparing an iron- containing green plant material concentrate comprising the steps of: a) suspending a green plant material in an aqueous liquid to form a green plant material suspension, b) blending the green plant material suspension to obtain a green plant material slurry, c) applying a physical mean on the green plant material slurry to separate and obtain an iron-containing green plant material concentrate, d) optionally, drying the iron-containing green plant material concentrate. A second aspect of the invention proposes an iron-containing green plant material concentrate which is obtainable or obtained by the process according to the first aspect of the invention. A third aspect of the invention proposes an iron-containing green plant material concentrate, which comprises at least 500 ppm iron by dry weight of iron-containing green plant material concentrate. A fourth aspect of the invention proposes a food product or a beverage comprising an iron-containing green plant material concentrate according to the second or the third aspect of the invention. A fifth aspect of the invention proposes a food supplement comprising an iron- containing green plant material concentrate according to the second or the third aspect of the invention. A sixth aspect of the invention proposes a cosmetic or a pharmaceutical composition comprising an iron-containing green plant material concentrate according to the second or the third aspect of the invention. A seventh aspect of the invention proposes a method for fortifying a food product or beverage with iron comprising preparing a food product or beverage and adding iron- containing green plant material concentrate according to the second or the third aspect of the invention in the food product or beverage. It has been discovered that the process of the invention allows the effective concentration of the iron from plant materials while allowing effective decrease of the ratio of undesirable compounds compared to iron, including insoluble plant materials and antinutritional factors that decrease or prevent iron absorption. The obtained concentrate has substantial amount of iron while having limited amount of antinutritional factors compared to iron, in particular antinutritional factors decreasing or preventing the absorption of iron in the body. The iron of the concentrate is coming from plant materials. Hence, it is from a natural source and is suitable for vegetarian/vegan diet. In addition, the concentrate has good sensory properties and does not impart or impart very limited sensory defects, in particular limited metallic off taste, when used in beverages, food supplements or food products. In addition, the concentrate has satisfactory iron bioaccessibility properties. These and other aspects, features and advantages of the invention will become more apparent to those skilled in the art from the detailed description of embodiments of the invention, in connection with the attached drawings. BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 shows iron content (mg/kg) based on dry weight (DW) in dry peppermint A, dry nettle, dry thyme A and B and their corresponding iron-containing green plant material concentrates obtained from them according to the method of example 1. Additionally, the iron content of two commercial extracts of peppermint, one commercial extract of nettle, and one commercial extract of thyme is reported. The values represent the average between triplicate independent samples and error bars represent the standard deviation. By “dry peppermint”, “dry nettle”, “dry thyme A”, “dry thyme B” in figure 1, it is understood the together of leaves and stems of the corresponding dry plant that were ground into powders before being further processed into the concentration process of example 1. For “Dry peppermint” in figure 1, the corresponding dry plant is dry peppermint A. Figure 2 shows the molar ratio (M/M) between iron and oxalic acid molar concentrations in dry peppermint A, dry nettle, iron-containing peppermint concentrate obtained from said dry peppermint A according to the method of example 1 and iron- containing nettle concentrate obtained from said dry nettle according to the method of example 1. The values represent the average between duplicate measurements. By “dry peppermint” and “dry nettle” in figure 2, it is understood the together of leaves and stems of respectively the dry peppermint plant A and the dry nettle plant that were ground into powders before being further processed into the concentration process of example 1. Figure 3 shows the molar ratio (M/M) between iron and phytic acid molar concentrations in dry peppermint A and B, nettle and thyme A and iron-containing concentrates obtained from respectively said dry peppermint A and B, nettle and thyme according to the method of example 1. The values represent the average between duplicate independent samples and error bars represent the standard deviation. By “dry peppermint A”, “dry peppermint B”, “dry nettle”, “dry thyme” in figure 3, it is understood the together of leaves and stems of the corresponding dry plant that were ground into powders before being further processed into the concentration process of example 1. For “Dry thyme” in figure 3, the corresponding dry plant is dry thyme A. Figure 4 shows the iron bioaccessibility of iron-containing peppermint concentrates prepared with water (according to the method of example 1) from dry peppermint B and iron- containing peppermint concentrates prepared with water in presence of respetively citric acid, hydrochloric acid, malic acid or ascorbic acid (according to the method of example 2) from dry peppermint B, compared to iron pyrophosphate. The values represent the average between duplicate independent samples and error bars represent the standard deviation. Figure 5 shows the iron bioaccessibility of iron-containing nettle concentrates prepared with water (according to example 1), and iron-containing nettle concentrates prepared with water in presence of respectively citric acid and hydrochloric acid (according to example 2). The values represent the average between duplicate independent samples and error bars represent the standard deviation. Figure 6 shows the absolute amount of bioaccessible iron contained in dry peppermint B and iron-containing peppermint concentrates prepared with water according to the concentration process of example 1 from dry peppermint B or with water in presence of respectively citric acid, hydrochloric acid, malic acid and ascorbic acid according to the concentration process of example 2 from dry peppermint B. The absolute amount of bioaccessible iron was calculated multiplying the iron content in the sample by the bioaccessibility value. The values represent the average between duplicate independent samples and error bars represent the standard deviation. By “dry peppermint” in figure 6, it is understood the together of leaves and stems of the dry peppermint plant B that were ground into powders before being further processed into the concentration process of example 1 or example 2. Figure 7 shows the absolute amount of bioaccessible iron contained in dry nettle, iron- containing nettle concentrates prepared with water (according to example 1), and iron- containing nettle concentrates prepared with water in presence of respectively citric acid and hydrochloric acid (according to example 2). The absolute amount of bioaccessible iron was calculated multiplying the iron content in the sample by the bioaccessibility value. The values represent the average between duplicate independent samples and error bars represent the standard deviation. By “dry nettle” in figure 7, it is understood the together of leaves and stems of the dry nettle plant that were ground into powders before being further processed into the concentration process of example 1 or example 2. Figure 8 shows the iron bioaccessibility of iron-containing thyme concentrates prepared with water (according to example 1) from dry thyme B, and iron-containing thyme concentrates prepared with water in presence of respectively citric acid and hydrochloric acid (according to example 2) from dry thyme B. The values represent the average between duplicate independent samples and error bars represent the standard deviation. Figure 9 shows the absolute amount of bioaccessible iron contained in dry thyme B, iron-containing thyme concentrates prepared with water (according to example 1) from dry thyme B, and iron-containing thyme concentrates prepared with water in presence of respectively citric acid and hydrochloric acid (according to example 2) from dry thyme B. The absolute amount of bioaccessible iron was calculated multiplying the iron content in the sample by the bioaccessibility value. The values represent the average between duplicate independent samples and error bars represent the standard deviation. By “dry thyme B” in figure 9, it is understood the together of leaves and stems of the dry thyme plant B that were ground into powders before being further processed into the concentration process of example 1 or example 2. Figure 10 shows the total phenolics content (mg gallic acid equivalent/g DW) in in dry peppermint B and dry nettle and iron-containing concentrates obtained from respectively said dry peppermint B and dry nettle according to the method of example 1. The values represent the average between duplicate independent samples and error bars represent the standard deviation. By “dry peppermint”, “dry nettle” in figure 10, it is understood the together of leaves and stems of the corresponding dry plant that were ground into powders before being further processed into the concentration process of example 1. For “Dry peppermint” in figure 3, the corresponding dry plant is dry peppermint B. DETAILED DESCRIPTION OF THE INVENTION As used herein, the words “comprise”, “comprising” and the like are to be construed in an inclusive sense, that is to say, in the sense of “including, but not limited to”, as opposed to an exclusive or exhaustive sense. Likewise, the terms “include,” “including” and “or” should all be construed to be inclusive, unless such a construction is clearly prohibited from the context. Nevertheless, the compositions/products disclosed herein may lack any element that is not specifically disclosed herein. Thus, a disclosure of an embodiment using the term “comprising” includes a disclosure of embodiments “consisting essentially of” and “consisting of” the components identified. All numerical ranges should be understood to include each integer, whole or fractions, within the range. Moreover, these numerical ranges should be construed as providing support for a claim directed to any number or subset of numbers in that range. For example, a disclosure of from 1 to 10 should be construed as supporting a range of from 1 to 8, from 3 to 7, from 1 to 9, from 3.6 to 4.6, from 3.5 to 9.9, and so forth. As used herein, the singular forms “a”, “an”, and “the” include plural referents unless the context clearly dictates otherwise. Thus, for example, reference to “a green plant material” or “the green plant material” includes one green plant material but also two or more green plant materials. Unless noted otherwise, all percentages in the specification refer to weight percent, where applicable. Unless defined otherwise, all technical and scientific terms have and should be given the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. As used herein, the term “and/or” used in the context of “X and/or Y” should be interpreted as “X,” or “Y,” or “X and Y.”. Similarly, “at least one of X or Y” should be interpreted as “X,” or “Y,” or “both X and Y.”. For example, “dried leaves and/or fresh leaves” means “dried leaves,” or “fresh leaves,” or “both dried leaves and fresh leaves.”. As used herein, the terms “example” and “such as,” particularly when followed by a listing of terms, are merely exemplary and illustrative and should not be deemed to be exclusive or comprehensive. But, a disclosure of an embodiment using the term “example” ,“such as” and “e.g.” includes a disclosure of embodiments where the terms are exclusive and/or comprehensive. As used herein, “related” mean occurring concurrently, preferably means caused by the same underlying disease or condition, and most preferably means that one of the identified diseases or conditions is caused by the other identified condition or disease. As used herein, the terms “treat” and "treatment" mean to administer a composition as disclosed herein to a subject having a condition in order to lessen, reduce or improve at least one symptom associated with the condition and/or to slow down, reduce or block the progression of the condition. The terms “treatment” and “treat” include both prophylactic or preventive treatment (that prevent and/or slow the development or progression of a targeted pathologic condition or disorder) and curative, therapeutic or disease-modifying treatment, including therapeutic measures that cure, slow down, lessen symptoms of, and/or halt progression of a diagnosed pathologic condition or disorder; and treatment of patients at risk of contracting a disease or suspected to have contracted a disease, as well as patients who are ill or have been diagnosed as suffering from a disease or medical condition. The terms “treatment” and “treat” do not necessarily imply that a subject is treated until total recovery. The terms “treatment” and “treat” also refer to the maintenance and/or promotion of health in an individual not suffering from a disease but who may be susceptible to the development of an unhealthy condition. The terms “treatment” and “treat” are also intended to include the potentiation or otherwise enhancement of one or more primary prophylactic or therapeutic measures. As non-limiting examples, a treatment can be performed by a patient, a caregiver, a doctor, a nurse, or another healthcare professional. Both human and veterinary treatments are within the scope of the present disclosure. As used herein, the terms "prevent and “prevention” mean to administer a composition as disclosed herein to a subject is not showing any symptoms of the condition to reduce or prevent development of at least one symptom associated with the condition. Furthermore, “prevention” includes reduction of risk, incidence and/or severity of a condition or disorder. As used herein, an “effective amount” is an amount that treats or prevents a deficiency, treats or prevents a disease or medical condition in an individual, or, more generally, reduces symptoms, manages progression of the disease, or provides a nutritional, physiological, or medical benefit to the individual. As used herein, the term “animal” includes, but is not limited to, mammals, which includes but is not limited to rodents; aquatic mammals; domestic animals such as dogs, cats and other pets; farm animals such as sheep, pigs, cows and horses; and humans. Where “animal,” “mammal” or a plural thereof is used, these terms also apply to any animal that is capable of the effect exhibited or intended to be exhibited by the context of the passage, e.g., an animal benefitting from iron fortification. While the term “individual” or “subject” is often used herein to refer to a human, the present disclosure is not so limited. Accordingly, the term “individual” or “subject” refers to any animal, mammal or human that can benefit from the methods and compositions disclosed herein. As used herein, the term “pet” means any animal which could benefit from or enjoy the compositions provided by the present disclosure. For example, the pet can be an avian, bovine, canine, equine, feline, hircine, lupine, murine, ovine, or porcine animal, but the pet can be any suitable animal. The term “companion animal” means a dog or a cat. As used herein, the term “green plant material” refers to plant materials that comprise chlorophylls and chloroplasts. These plant materials are generally green due to the presence of chlorophylls, which are photosynthetic pigments. The green plant materials may also be designated as chlorophyll-containing plant materials. As used herein, the term “added organic solvent” refers to an organic solvent which is exogenous to the green plant material and that is added in addition to the green plant material for the preparation of the iron-containing green plant material concentrate. The term “added organic solvent” excludes organic solvent that are inherently present in the green plant material of the iron-containing green plant material concentrate. As used herein, the term “vegan” refers to an edible composition which is entirely devoid of animal products, or animal derived products. As used herein, the term “vegetarian” refers to an edible composition which is devoid of meat, including fish. As used herein, the term “bioaccessibility” refers to the fraction of the total amount of a substance that is potentially available for absorption. For example, this refers to the fraction of said substance that is potentially available for absorption in a subject, in particular in the gastrointestinal tract of said subject. As used herein, the term “GAE” refers to the Gallic Acid Equivalent. This term is used when the content of a component is quantified against a gallic acid calibration curve. Gallic acid equivalent means that each component quantified was considered equivalent to one molecule of gallic acid. In other words, 1 mg GAE/g of the quantified component is equivalent to 1 mg/g of said quantified component. As used herein, the terms “blend” and “mix” are used interchangeably. In a first aspect, the invention relates to a process for preparing an iron-containing green plant material concentrate. The process comprises a step a) of suspending a green plant material in an aqueous liquid to form a green plant material suspension. In an embodiment, the ratio of plant green plant material to aqueous liquid (w/v) within the green plant material suspension is of 1:3 to 1:20, preferably of 1:5 to 1:20, more preferably 1:10 to 1:20, most preferably 1:12 to 1:18. The green plant material comprises plant cells. Likewise, the green plant material suspension comprises plant cells, including intact plant cells. The plant cells of the green plant material suspension comes from the green plant material. The green plant material suspension is the resulting product of step a). The green plant material slurry is the resulting product of step b). The green plant material suspension and green plant material slurry are different. In particular, in the green plant material slurry, the plant cells are disrupted, and the intracellular material of the plant cells is released while in the green plant material suspension, the plant cells are not disrupted such that the intracellular material of the plant cells is not released. The aqueous liquid and so the green plant material suspension are free from added organic solvent. For example, the aqueous liquid and so the green plant material suspension are free from any added organic solvent selected from the list consisting of acetone, acetonitrile, benzene, 1-butanol, 2-butanol, 3-butanone, t-butyl alcohol, carbon tetrachloride, chlorobenzene, chloroform, cyclohexane, diethylene glycol, diethyl ether, diethylene glycol dimethyl ether, 1,2-dimethoxy-ethane (glyme, DME), dimethyl-formamide (DMF), dimethyl sulfoxide (DMSO), 1,4 dioxane, 1,2-dicholoroethane, ethanol, ethyl acetate, ethylene glycol, glycerin, heptane, hexamethylphosphoramide (HMPA), hexane, methanol, methylene chloride, N-methyl-2-pyrrolidinone (NMP), nitromethane, naphthalene, pentane, 1-propanol, 2-propanol, pyridine, toluene, triethyl amine, tricine, tris, tetrahydrofuran, o-xylene, m- xylene, p-xylene and combination thereof. In a preferred embodiment, the aqueous liquid comprises at least 80wt.% water, more preferably 90wt.% water, even more preferably at least 95wt.% water. Most preferably, the aqueous liquid is water. In an embodiment, osmotic agent may be further added to the green plant material suspension before step b). The osmotic agent may be selected from the list consisting of glucose, glycerol, sucrose, sorbitol, sodium chloride, potassium chloride or a combination thereof. Preferably, the osmotic agent is sucrose. The quantity of the osmotic agent to be added to the green plant material suspension may be defined easily by a person having ordinary skills in the art depending on the type of the osmotic agent and the osmolarity of the suspension. The osmotic agent may be used to modulate the osmotic pressure. Without wishing to be bound by theory, this may contribute to keep some plant structures that store iron intact and avoid their lysis upon osmolar pressure. Without wishing to be bound by theory, this may allow to further improve iron stability. In a preferred embodiment, acid may be further added to the green plant material suspension before step b). In an embodiment, the acid is added to the green plant material suspension before step b) until reaching a pH of 2 to 5.5, preferably 2.5 to 4.5, most preferably 3 to 4. The acid may be selected from the group consisting of hydrochloric acid, citric acid, malic acid, ascorbic acid, acetic acid, lactic acid, propionic acid, fumaric acid, tartaric acid, phosphoric acid, adipic acid, succinic acid, gluconic acid or a mixture thereof. Preferably, the acid is selected from the group consisting of ascorbic acid, malic acid, citric acid, hydrochloric acid or a mixture thereof. In a more preferred embodiment, the acid is selected from the group consisting of malic acid, citric acid, hydrochloric acid or a mixture thereof. In an even more preferred embodiment, the acid is selected from the group consisting of citric acid, hydrochloric acid or a mixture thereof. In a most preferred embodiment, the acid is hydrochloric acid. In another most preferred embodiment, the acid is citric acid. The acid may be provided as pure acid solution, as diluted acid solution or as acid-containing food ingredient. Examples of acid-containing food ingredient include citrus juice such as lemon juice, lime juice, orange juice, tangerine juice and the like. The green plant material suspension may comprise 0.01wt% to 5wt% of acid. When the acid is citric acid, the green plant material suspension may comprise 0.01 to 3wt% citric acid, preferably 0.5 to 2.3wt% citric acid. When the acid is hydrochloric acid, the green plant material suspension may comprise 0.01 % to 0.5 wt% hydrochloric acid, preferably 0.02 to 0.54wt% hydrochloric acid. When the acid is malic acid, the green plant material suspension may comprise 0.01 % to 3 wt% malic acid, preferably 0.5 to 2.5 wt% malic acid. The use of acid has a dual effect. In particular, the acid decreases the pH and chelates iron. The decrease in pH and iron chelation contributes to improve iron solubility and so contributes to improve iron bioaccessibility in the iron-containing green plant material concentrate. Advantageously, the green plant material comes from herb or duckweed. In some embodiment, the green plant material may be a combination of green plant material coming from herb or duckweed in combination with algae and/or cyanobacteria. Non-limiting example of algae include Chlorella vulgaris. Non-limiting example of cyanobacteria include Arthrospira platensis. Duckweed is a floating aquatic green plant that may also be designated as water lentil. In a preferred embodiment, the duckweed is from one of the following genus: Spirodela, Landoltia, Lemna, Wolffia or Wollffiella. The use of duckweed allows to maximize the amount of iron. Other advantages of the use of duckweed is that duckweed has a high growth rate, that it can tolerate extreme circumstances and that it can be cultivated in a basin on non- arable land, thereby avoiding the use of farming land. In a preferred embodiment, the green plant material comes from herb from Lamiaceae family and/or herb from Apiaceae family and/or herb from Urticaceae family. Examples of herb from Lamiaceae family include mint, thyme, lemonbalm, basil, sage, oregano, rosemary, basil, chervil, savory or a combination thereof. Examples of herb from Apiaceae family include parsley, coriander, dill or a combination thereof. Examples of herb from Urticaceae family include nettle. In a more preferred embodiment, the green plant material comes from herb, wherein the herb is selected from the group consisting of parsley, coriander, mint, thyme, lemon balm, nettle, sage, oregano, rosemary, basil, dill, chervil, savory or a mixture thereof. Preferably, the herb is selected from the group consisting of sage, oregano, parsley, coriander, mint, thyme, lemon balm, nettle or a mixture thereof. More preferably, herb is selected from the group consisting of sage, oregano, parsley, coriander, mint, thyme, lemon balm, nettle or a mixture thereof. Even more preferably, the herb is selected form the group consisting of mint, thyme, lemon balm, nettle, sage, oregano or a mixture thereof. Most preferably, the herb is selected from the group consisting of mint, thyme, lemon balm, nettle or a mixture thereof. The use of herbs, in particular the use of this list of selected herbs, allows to maximize the amount of iron in the iron-containing green plant material concentrate while imparting pleasant flavour. In an embodiment, the mint may be spearmint, peppermint or a mixture thereof. Parsley generally comprises 20-600 ppm iron. Coriander generally comprises 20-300 ppm iron. Mint generally comprises 200-1000 ppm iron. Thyme generally comprises 200-3000 ppm. Lemon balm generally comprises 300-600 ppm iron. Nettle generally comprises 100- 1000 ppm iron. Sage generally comprises 200-1300 ppm iron. Oregano generally comprises 200-1000 ppm iron. Rosemary generally comprises 20-500 ppm iron. Basil generally comprises 20-900 ppm iron. Dill generally comprises 20-500 ppm iron. Chervil generally comprises 20- 400 ppm iron. Savory generally comprises 50-400 ppm iron. In some embodiment, parsley refers to any plants from the genus Petroselinum, preferably any edible plants from the genus Petroselinum. Preferably, parsley refers to Petroselinum crispum. In some embodiment, coriander refers to any plants from the genus Coriandrum, preferably any edible plants from the genus Coriandrum. Preferably, coriander refers to Coriandrum sativum. In some embodiment, mint refers to any plants from the genus Mentha, preferably any edible plants from the genus Mentha. More preferably, mint refers to plant selected from the list consisting of Mentha spicata, Mentha × piperita or a combination thereof. In some embodiment, thyme refers to any plants from the genus Thymus, preferably any edible plants from the genus Thymus. Preferably, thyme refers to Thymus vulgaris. In some embodiment, lemon balm refers to any plants from the genus Melissa, preferably any edible plants from the genus Melissa. Preferably, lemon balm refers to Melissa officinalis. In some embodiment, nettle refers to any plants from the genus Urtica, preferably any edible plants from the genus Urtica. Preferably, nettle refers to Urtica dioica. In some embodiment, sage refers to any plants from the genus Salvia, preferably any edible plants from the genus Salvia. Preferably, sage refers to plant selected from the list consisting of Salvia officinalis, Salvia elegans or a combination thereof. In some embodiment, oregano refers to any plants from the genus Origanum, preferably any edible plants from the genus Origanum. Preferably, oregano refers to plant selected from the list consisting of Origanum vulgare, Origanum majorana or a combination thereof. More preferably, oregano refers to Origanum vulgare. In some embodiment, rosemary refers to any plants from the genus Rosmarinus, preferably any edible plants from the genus Rosmarinus. Preferably, rosemary refers to Rosmarinus officinalis. In some embodiment, basil refers to any plants from the genus Ocimum, preferably any edible plants from the genus Ocimum. Preferably, basil refers to Ocimum basilicum. In some embodiment, dill refers to any plants from the genus Anethum, preferably any edible plants from the genus Anethum. Preferably, dill refers to Anethum graveolens. In some embodiment, chervil refers to any plants from the genus Anthriscus, preferably any edible plants from the genus Anthriscus. Preferably, chervil refers to Anthriscus cerefolium. In some embodiment, savory refers to any plants from the genus Satureja, preferably any edible plants from the genus Satureja. Preferably, savory refers to plant selected from the list consisting of Satureja hortensis, Satureja montana or a combination thereof. In some embodiment, the green plant material does not come from curry tree, in particular the green plant material does not come from Murraya koenigii and/or Bergera koenigii. Green plant materials from curry tree are not advantageous for the present invention. For example, they may result in iron containing-green plant material concentrate with unpleasant sensory properties, including metallic off-notes. Saffron spice is not a green plant material. In some embodiment, the green plant material does not come from saffron, in particular does not come from Crocus sativus. In some embodiment, the green plant material is different from Tagetes erecta L.. In some embodiment, the green plant material is different Artemisia dracunculus, Cichoria endivia and Lactuca sativa. In some embodiment, the green plant material is not coming from a berry. Examples of berry include wolfberries, blueberries, cranberries, white currants, red currants, blackcurrants, mulberries, blackberries, gooseberries, raspberries, sea buckthorns, strawberries, arbutus berries, grapes, or combinations thereof. In some embodiment, the green plant material is not coming from blueberry, in particular Vaccinium sect. cyanococcus. The green plant material may comprise any part of the green plant such as leaves, stems, flowers, buds, roots. In an embodiment, the green plant material comprises leaves. In an embodiment, the green plant material comprises leaves and stems. Preferably, the green plant material comprises a substantial quantity of leaves. The green plant material comprises at least 80wt.% leaves, more preferably at least 90wt.% leaves, even more preferably at least 95wt.% leaves, even more preferably at least 98wt.% leaves. The remainder of the green plant material may be any parts of the green plant different from leaves as disclosed herein. In an embodiment, the remainder of the green plant material consists only stems. In a most preferred embodiment, the green plant material consists only of leaves. The leaves are preferred because they generally contain a high fraction of iron in the green plant while being edible. Hence, the leaves are a good edible starting materials to concentrate substantial amount of iron from green plants. In an embodiment, the green plant material is dried green plant material and/or fresh green plant material. For example, the green plant material is dried leaves and/or fresh leaves. Advantageously, the green plant material is dried green plant material. Dried plant materials are more convenient to handle on an industrial scale as they have a longer shelf-life than fresh plant material. In an embodiment, when the green plant material comprises or is dried green plant material, the dried green plant may be ground to a powder before step a). The dried green plant material may be ground via dry milling. Dry milling may be obtained using any machine providing shear or containing a cutting device. For example, the dry milling may be performed by means of hammer mill, stone mill, roller mill, ball mill, jet mill, colloidal mill, stirred media mill, bead mill, pin mill, roller grinder, roller refiner, impact mill, cryogenic milling, rod mill, vibratory mill, cutting mill, disc mill, perforated disc mill, microcut mill or extrusion apparatus. The process further comprises a step b) of blending the green plant material suspension to obtain a green plant material slurry. For example, the blending may be performed by means of any kind of shearing or mixing device. Examples of mixing devices are: mixer, kitchen mixer, tumbler blender, paddle mixer, agitator, flow impeller, planetary mixer, multi shaft mixer, Scanima mixer or Stephan mixer. In an embodiment, the blending may be performed in step b) for at least 8 seconds, preferably for 8 seconds to 5 minutes, more preferably for 1 minute to 3 minutes. In an embodiment, the blending may be performed in step b) at a temperature of 4 to 80°C, preferably at a temperature of 4 to 25°C, more preferably at a temperature of 10 to 25°C. The preferred temperature range of 4 to 25°C is advantageous as it limits oxidation/chemical degradation of plant organelles that can occur at high temperature, e.g.60°C to 100°C. For example, the blending may be performed at room temperature. This step allows to disrupt the plant cells and release their intracellular material, including iron. This contributes to improve iron bioaccessibility in the final concentrate when ingested by humans. The process further comprises a step c) of applying a physical mean on the green plant material slurry to separate and obtain an iron-containing green plant material concentrate. In an embodiment, the step c) is performed through filtration and/or centrifugation and/or decantation and/or heat treatment. The filtration of step c) may be performed with the same conditions or features of the filtration step c₁) provided below in section “Step c₁) of filtration”. The heat treatment of step c) may be performed with the same conditions or features of the heat treatment step c₂) provided below in section “Step c₂) of heat treatment”. The decantation or centrifugation of step c) may be performed with the same conditions or features of the decantation or centrifugation step c₃) provided below in section “Step c₃) of decantation or centrifugation”. In an embodiment, the step c) of applying a physical mean is performed through the steps of: c₁) filtering the green plant material slurry to obtain a permeate, c₂) optionally, heat-treating the permeate, c3) centrifugating or decanting the permeate to obtain an iron-containing green plant material concentrate. Step c1) of filtration As mentioned above, in an embodiment, the process may comprise a step c₁) of filtering the green plant material slurry of step b) to obtain a permeate. After the step c1) of filtration, a retentate and a permeate are obtained. Material that passes through a filter is called “permeate”; material that does not pass through a filter and is recirculated is called “retentate”. The retentate is removed after step c1) and the permeate is recovered and further processed after step c1). In a preferred embodiment, the step c1) of filtration is performed with a filter having a mesh of 25 µm to 1000µm, preferably of 25 µm to 500µm, more preferably of 100 µm to 200µm. This mesh size contributes to separate, concentrate and so increase the purity in compounds of interests, such as iron while discarding/decreasing undesired compounds such as insoluble plant compounds. The mesh size also decreases the particle size of the iron- containing green plant material concentrate to a level such that the concentrate is less incline to sedimentation, in particular when use in beverages or liquid/semi-liquid food products or liquid/semi-liquid food supplements or liquid/semi-liquid cosmetic compositions or liquid/semi-liquid pharmaceutical compositions. The step c1) of filtration may be performed in one or several steps. In an embodiment, the step c₁) of filtration may be performed in one to ten steps, preferably one to five steps. When the step c1) of filtration is performed in several steps, i.e. in two to ten steps, preferably two to five steps, the size of the mesh of the filter decreases at each consecutive filtration step. In other words, the size of the mesh of the filter used in a predetermined step of filtration (e.g. first step of filtration) is higher than the size of the mesh of the filter used in the consecutive and downstream step of filtration (e.g. second step of filtration) and so on. In a more preferred embodiment, the step c₁) of filtration is performed in two steps, in particular the green plant material slurry is first filtered with a filter having a mesh of 400 to 500 microns, preferably of 500 microns and then filtered with a filter having a mesh of 50 to 200 microns, preferably of 180 microns. The performance of the filtration step in several steps, in particular two steps, decreases the propensity of the filter to clog. In an embodiment, the sequence of steps a), b) and c₁) is repeated at least two times, preferably 2 to 5 times before step c2) and as of the second sequence of steps a), b) and c1), the green plant material of step a) is replaced by the retentate obtained in the step c₁) of the preceding sequence of steps a), b) and c1). For sake of clarity, as of the second sequence of steps a), b) and c1), the retentate of the preceding sequence of steps a), b) and c1) is suspended in an aqueous liquid in step a) of the consecutive sequence of steps a), b) and c₁) instead of the green plant material. Hence, as of the second sequence of steps a), b) and c1), the suspension of step a) and b) is not a green plant material suspension but a retentate suspension and the slurry of step b) and c1) is not a green plant material slurry but a retentate slurry. In addition, as of the second sequence of steps a), b) and c1), a permeate is still obtained in step c1). Moreover, as of the second sequence of steps a), b) and c1), a retentate is also still obtained in step c1). The obtained retentate may be further processed in the consecutive sequence of steps a), b) and c1) and so on. Step c2) of heat treatment As mentioned above, in an embodiment, the process may comprise a step c2) of optionally heat-treating the permeate obtained in step c1). This heat treatment step allows to extend the shelf-life of the final iron-containing green plant material concentrate. In an embodiment, this step c2) is not optional. In an embodiment, the step c2) of heat treatment is performed at a temperature of at least 60°C for at least 2 seconds. Preferably, the step c2) of heat treatment is performed at a temperature of 60-125°C for 2 seconds to 30 minutes. More preferably, the step c₂) of heat treatment is performed at a temperature of 70-85°C for 1 minute to 3 minutes. Step c₃) of decantation or centrifugation As mentioned above, in an embodiment, the process may comprise a step c₃) of centrifugating or decanting the permeate to obtain an iron-containing green plant material concentrate. Preferably, the step c₃) is a step of centrifugating the permeate. In an embodiment, the step c₃) of centrifugation is performed at 500 to 10000g, preferably at 1000g to 5000g, more preferably 1000g to 3000g. In an embodiment, the step c₃) of centrifugation is performed for 2 to 30 minutes, preferably 2 to 20 minutes, more preferably 5 to 15 minutes. After centrifugation or decantation, a supernatant and a precipitate are obtained. The precipitate corresponds to the material, which is generally solid or semi-solid, that forms deposits at the bottom of the centrifugation/decantation container while the supernatant corresponds to the material, which is generally liquid, that floats or lies above the precipitate. The supernatant is discarded. The precipitate is recovered. The precipitate obtained after step c3) corresponds to the iron-containing green plant material concentrate. In an embodiment, the step c3) of centrifugation or decantation is performed one time. In other words, the precipitate obtained in step c₃) is not further centrifuged or decanted. The process further comprises a step d) of optionally drying the iron-containing green plant material concentrate to obtain an iron-containing green plant material concentrate in powder form. After step d), the iron-containing green plant material concentrate is not in the form of a semi-solid but is in the form of a powder. For example, the step of drying may be performed by spray drying, roller drying, air drying or freeze drying. In an embodiment, the step d) of drying is not optional. As an alternative to the drying of the iron-containing green plant material concentrate into powder, the water activity of the iron-containing green plant material concentrate may be decreased to improve its microbiological stability over time. Hence, in an alternative embodiment, the process may comprise after step c) of application of physical mean or step c3) of centrifugation or decantation, a step d’) of decreasing the water activity of the iron- containing green plant material concentrate. After step d’) of decreasing the water activity, the iron iron-containing green plant material concentrate has a water activity below 0.85, preferably of 0.5 to 0.85. After this step d’) of water activity decrease, the iron-containing green plant material concentrate is not in powder form. Indeed, the iron-containing green plant material concentrate obtained after step d’) is in the same form as the iron-containing green plant material concentrate obtained after step c) or step c₃), i.e. in semi-solid form. But, the iron-containing green plant material concentrate obtained after step d’) has a water activity which is lower than the water activity of the iron-containing green plant material concentrate obtained just after step c) or step c₃). This step d’) of decreasing the water activity may be performed by evaporating the iron-containing green plant material concentrate, by drying iron-containing green plant material concentrate or by adding a humectant to the iron- containing green plant material concentrate. Preferably, the humectant is sucrose. The quantity of the humectant to be added to the iron-containing green plant material concentrate may be defined easily by a person having ordinary skills in the art depending on the type of the humectant and the targeted water activity. The drying may be performed by freeze drying, spray drying, air drying or roller drying. The evaporation step may be performed with an evaporator. In some embodiment, the step d’) of decreasing the water activity of the iron- containing green plant material concentrate and the step d) of drying the iron-containing green plant material concentrate may be performed sequentially. In this embodiment, the step d’) of decreasing the water activity of the iron-containing green plant material concentrate is before the step d) of drying the iron-containing green plant material concentrate. In some embodiment, in particular when a step d) of drying is applied, the process does not comprise evaporation or drying before step d) of drying. In some embodiment, in particular when a step d) of drying is applied, the process does not comprise any step of evaporation or drying. In some embodiment, when a step d) of drying is not applied, the process does not comprise any step of evaporation or drying. In some embodiment, the step c) is not performed by evaporation or does not comprise any use of evaporation machine, such as rotavapor. Likewise, step c1, c2, c3 and c4 are not performed by evaporation or do not comprise any evaporation, any use of evaporation machine, such as rotavapor. It has been observed that the iron concentration in ppm in the final concentrate is significantly increased in the process of the invention compared to processes, such as the one of RO132538A0, that apply drying or evaporation as a concentration method, directly on the permeate without additional physical separation, in particular without centrifugation step. In some embodiment, the process may comprise a step d”) of heat-treating the iron- containing green plant material concentrate after step c) or step c₃). This step d”) of heat treatment may be before or after step d’). This step d”) of heat treatment may be before or after step d). This step d”) of heat treatment may be performed at a temperature of at least 60°C for at least 2 seconds. Preferably, the step d”) of heat treatment is performed at a temperature of 60-125°C for 2 seconds to 30 minutes. The process allows the effective concentration of the iron while allowing effective decrease of the ratio of undesirable compounds compared to iron, including insoluble plant materials and antinutritional factors that decrease or prevent iron absorption. The obtained concentrate has substantial amount of iron while having limited amount of antinutritional factors compared to iron, in particular antinutritional factors decreasing or preventing the absorption of iron in the body. The iron of the concentrate is coming from plant materials. Hence, it is from a natural source and is suitable for vegetarian/vegan diet. In addition, the concentrate has good sensory properties and does not impart or impart very limited sensory defects, in particular limited metallic off taste, when use in beverages, food supplements, food products or pharmaceutical compositions. In addition, the iron of the concentrate has satisfactory bioaccessibility properties. The process is substantially natural. It does not involve the use of added organic solvent but still allow effective concentration of iron and effective decrease of the ratio of undesirable compounds compared to iron, including antinutritional factors that decrease or prevent iron absorption in body. In a preferred embodiment, the process does not involve the use of any added organic solvent. For example, the process does not involve the use of any added organic solvent selected from the list consisting of acetone, acetonitrile, benzene, 1-butanol, 2-butanol, 3- butanone, t-butyl alcohol, carbon tetrachloride, chlorobenzene, chloroform, cyclohexane, diethylene glycol, diethyl ether, diethylene glycol dimethyl ether, 1,2-dimethoxy-ethane (glyme, DME), dimethyl-formamide (DMF), dimethyl sulfoxide (DMSO), 1,4 dioxane, 1,2- dicholoroethane, ethanol, ethyl acetate, ethylene glycol, glycerin, heptane, hexamethylphosphoramide (HMPA), hexane, methanol, methylene chloride, N-methyl-2- pyrrolidinone (NMP), nitromethane, naphthalene, pentane, 1-propanol, 2-propanol, pyridine, toluene, triethyl amine, tricine, tris, tetrahydrofuran, o-xylene, m-xylene, p-xylene and combination thereof. As a result, in a preferred embodiment, the iron-containing green plant material concentrate is free from added organic solvent. For example, the iron-containing green plant material concentrate is free from any added organic solvent listed above. The process of the invention allows to effectively concentrate iron of the green plant material. Advantageously, the iron concentration by weight percent is at least 2 times higher, preferably 2 to 10 times higher in the iron-containing green plant material concentrate obtained in step c) or c₃) than in the green plant material of step a). For example, the concentration of iron in the concentrate and the green plant material may be measured according to the method provided in the examples. The process of the invention allows to effectively decrease the ratio of undesirable antinutritional factors compared to iron, in particular antinutritional factors that may decrease or prevent absorption of iron in body. In particular, the molar ratio of iron to oxalic acid (M/M) is significantly increased through the process of the invention. It is advantageous to increase the molar ratio of iron to oxalic acid to decrease the impact of oxalic acid on iron. Indeed, oxalic acid may decrease or prevent absorption of iron in body. Advantageously, the molar ratio of iron to oxalic acid is at least 2 times higher, preferably 2 to 10 times, more preferably 3 to 10 times higher in the iron- containing green plant material concentrate obtained in step c) or c3) than in the green plant material of step a). The molar ratio of iron to oxalic acid of the iron-containing green plant material concentrate is expressed by dry weight of the iron-containing green plant material concentrate. The molar ratio of iron to oxalic acid of the green plant material is expressed by dry weight of the green plant material. For example, the molar ratio of iron to oxalic acid in the concentrate and the green plant material may be measured according to the method provided in the examples. In some embodiment, the molar ratio of iron to phytic acid (M/M) is significantly increased through the process of the invention. It is advantageous to increase the molar ratio of iron to phytic acid to decrease the impact of phytic acid on iron. Indeed, phytic acid may decrease or prevent absorption of iron in body. Advantageously, the molar ratio of iron to phytic acid is at least 2 times higher, preferably 2 to 10 times, more preferably 3 to 10 times higher in the iron-containing green plant material concentrate obtained in step c) or c3) than in the green plant material of step a). The molar ratio of iron to phytic acid of the iron- containing green plant material concentrate is expressed by dry weight of the iron-containing green plant material concentrate. The molar ratio of iron to phytic acid of the green plant material is expressed by dry weight of the green plant material. The molar ratio of iron to phytic acid may be measured according to the method provided in the examples. In addition, the amount of total phenolic compounds, is significantly reduced through the process of the invention. In particular, it is advantageous to reduce phenolic compounds as phenolic compounds may prevent decrease or prevent absorption of iron. Advantageously, the total phenolic compound concentration by weight percent is at least 2 times lower, preferably at least 5 times lower in the iron-containing green plant material concentrate obtained in step c) or c₃) than in the green plant material of step a). In particular, the total phenolic compound concentration by weight percent is 2-15 times lower, preferably at least 5-15 times lower in the iron-containing green plant material concentrate obtained in step c) or c₃) than in the green plant material of step a). In some embodiment, the process does not comprise any steps of addition of enzymes. For example, the process does not comprise any steps of addition of protein-degrading enzymes, carbohydrate-degrading enzymes, fibre-degrading enzymes, oxalic acid-degrading enzymes, phytic acid-degrading enzymes and/or phenolic compound-degrading enzymes. In a second aspect, the invention relates to an iron-containing green plant material concentrate which is obtainable or obtained by the process according to the first aspect of the invention. The features of the iron-containing green plant material concentrate of the third aspect of the invention also apply to the iron-containing green plant material concentrate of the present second aspect of the invention. The concentrate has substantial amount of iron and has limited amount of undesirable antinutritional factors compared to iron, in particular antinutritional factors that may decrease or prevent iron absorption. The iron of the concentrate is coming from plant materials. Hence, it is from a natural source and is suitable for vegetarian/vegan diet. In addition, the concentrate has good sensory properties and does not impart or impart very limited sensory defects, in particular limited metallic off taste, when use in beverages, food supplements, food products or pharmaceutical compositions. In addition, the iron of the concentrate has satisfactory bioaccessibility properties. The concentrate is natural and may be used to fortify food supplements, food products and beverages with iron, including vegetarian/vegan food supplements, food products and beverages. In a third aspect, an iron-containing green plant material concentrate which comprises at least 500 ppm iron by dry weight of the iron-containing green plant material concentrate. In an embodiment, the iron-containing green plant material concentrate comprises at least 1000 ppm iron on dry weight basis, preferably at least 1500 ppm iron by dry weight of iron-containing green plant material concentrate. In an embodiment, the iron-containing green plant material concentrate comprises at most 15000 ppm iron, preferably at most 4000 ppm by dry weight of iron-containing green plant material concentrate. In an embodiment, the iron-containing green plant material concentrate is coming from a green plant material. In particular, the iron-containing green plant material concentrate comprises a green plant material. The green plant material may be a green plant material as provided in the first aspect of the invention. For example, the concentration of iron of the iron-containing green plant material concentrate may be measured according to the method provided in the examples. In some embodiment, the iron-containing green plant material comprises less than less than 100 mg, preferably less than 50mg GAE/g total phenolic compounds by dry weight of iron-containing green plant material concentrate. In some embodiment, the iron-containing green plant material concentrate has an iron bioaccessibility of at least 3%, preferably at least 10%, more preferably of at least 15%. In some further embodiment, the iron-containing green plant material concentrate has an iron bioaccessibility of at most 50%, preferably at most 35%. The iron bioaccessibility of the iron- containing green plant material concentrate may be measured as provided in the examples. In an embodiment, the iron-containing green plant material concentrate has an absolute amount of bioaccessible iron of at least 35 ppm, preferably of at least 100 ppm, more preferably of at least 300 ppm, even more preferably of at least 450 ppm. In some further embodiment, the iron-containing green plant material concentrate has an absolute amount of bioaccessible iron of at most 1500 ppm, preferably of at most 1000 ppm, more preferably of at most 800 ppm, even more preferably of at most 500 ppm, even more preferably of at most 200 ppm. For example, the absolute amount of bioaccessible iron of the iron-containing green plant material concentrate may be measured according to the method provided in the examples. In some embodiment, the iron-containing green plant material concentrate has a molar ratio of iron to oxalic acid (M/M) of at least 0.3, preferably 0.3 to 3, more preferably 0.4 to 3, most preferably 0.4 to 1.5. The molar ratio of iron to oxalic acid is expressed by dry weight of the iron-containing green plant material concentrate. For example, the molar ratio of iron to oxalic acid of the iron-containing green plant material concentrate may be measured according to the method provided in the examples. In some embodiment, the iron-containing green plant material concentrate comprises less than 15000 ppm, preferably less than 12000 ppm, more preferably less than 10500 ppm oxalic acid by dry weight of iron-containing green plant material concentrate. For example, the concentration of oxalic acid in the iron-containing green plant material concentrate may be measured according to the method provided in the examples. In some embodiment, the iron-containing green plant material concentrate has a molar ratio of iron to phytic acid (M/M) of at least 5, preferably at least 7, more preferably at least 7.5. In particular embodiment, the iron-containing green plant material concentrate has a molar ratio of iron to phytic acid (M/M) of 5 to 80, preferably 7 to 80, more preferably 7.5 to 80, even more preferably 7.5 to 60, most preferably 7.5 to 50. The molar ratio of iron to phytic acid is expressed by dry weight of the iron-containing green plant material concentrate. For example, the concentration of iron may be measured according to the method provided in the examples. For example, the molar ratio of iron to phytic acid of the iron-containing green plant material concentrate may be measured according to the method provided in the examples. In some embodiment, the iron-containing green plant material concentrate comprises less than 3000 ppm, preferably less than 2000 ppm, more preferably less than 1650ppm phytic acid by dry weight of iron-containing green plant material concentrate. For example, the concentration of phytic acid of the iron-containing green plant material concentrate may be measured according to the method provided in the examples. In an embodiment, the iron-containing green plant material concentrate is free from added organic solvent, in particular is free from any added organic solvent listed in the first aspect of the invention. In an embodiment, the iron-containing green plant material concentrate has a pH of 3 to 8. In an embodiment, the iron-containing green plant material concentrate comprises 0.01% to 5% wt% of acid. The acid may be an acid as provided in the first aspect of the invention. Preferably, the acid is selected from the group consisting of ascorbic acid, malic acid, citric acid, hydrochloric acid or a mixture thereof. In a more preferred embodiment, the acid is selected from the group consisting of malic acid, citric acid, hydrochloric acid or a mixture thereof. In an even more preferred embodiment, the acid is selected from the group consisting of citric acid, hydrochloric acid or a mixture thereof. In a most preferred embodiment, the acid is hydrochloric acid. In another most preferred embodiment, the acid is citric acid. The acid may be provided as pure acid solution, as diluted acid solution or as acid- containing food ingredient. Examples of acid-containing food ingredients include citrus juice such as lemon juice, lime juice, orange juice, tangerine juice and the like. When the acid is citric acid, the iron-containing green plant material concentrate may comprise 0.01 to 3wt%, preferably 0.5 to 2.3wt% citric acid. When the acid is hydrochloric acid, the iron-containing green plant material concentrate may comprise 0.01 % to 0.5wt% hydrochloric acid, preferably 0.05 to 0.5wt% hydrochloric acid. When the acid is malic acid, the iron-containing green plant material concentrate may comprise 0.01 % to 3wt% malic acid, preferably 0.5 to 2.5wt% malic acid. In an embodiment, the iron-containing green plant material concentrate may comprise an osmotic agent. The osmotic agent may be an osmotic agent as provided in the first aspect of the invention. In an embodiment, the iron-containing green plant material concentrate may comprise a humectant. The humectant may be a humectant as provided in the first aspect of the invention. In an embodiment, the iron-containing green plant material concentrate may comprise a total sucrose content of 1 to 50 wt.%, preferably 5 to 20 wt.%. The sucrose in the iron- containing green plant material concentrate may be used as humectant and/or osmotic agent. The total sucrose content range provided herein applies regardless sucrose is used as humectant and/or osmotic agent. The features of the iron-containing green plant material concentrate of the third aspect of the invention also apply to the iron-containing green plant material concentrate provided in the first and second aspect of the invention, and vice versa. The concentrate has substantial amount of iron and has limited amount of undesirable antinutritional factors compared to iron, in particular antinutritional factors that may decrease or prevent iron absorption. The iron of the concentrate is coming from plant materials. Hence, it is from a natural source and is suitable for vegetarian/vegan diet. In addition, the concentrate has good sensory properties and does not impart or impart very limited sensory defects, in particular very limited metallic off taste, when use in food supplements, beverages, food products or pharmaceutical compositions. In addition, the iron of the concentrate has satisfactory bioaccessibility properties. The concentrate is natural and may be used to fortify food products, food supplements and beverages, including vegetarian/vegan food products, food supplements and beverages, with iron. In a fourth aspect, the invention relates to a food product or a beverage comprising an iron-containing green plant material concentrate according to the second or the third aspect of the invention. The iron-containing green plant material concentrate of the invention may be used to fortify food products and beverages with iron. The iron-containing green plant material concentrate has good sensory properties and does not impart or impart very limited sensory defects, in particular metallic off taste, when use in beverages or food products. In an embodiment, the food product or the beverage may have a pH of 2,5 to 8. In an embodiment, the food product or the beverage may comprise an acid content of 0.01 to 0.2wt%, preferably 0.02 to 0.1wt%. The acid may be an acid as provided in the first aspect of the invention. Preferably, the acid is selected from the group consisting of ascorbic acid, malic acid, citric acid, hydrochloric acid or a mixture thereof. In a more preferred embodiment, the acid is selected from the group consisting of malic acid, citric acid, hydrochloric acid or a mixture thereof. In an even more preferred embodiment, the acid is selected from the group consisting of citric acid, hydrochloric acid or a mixture thereof. In a most preferred embodiment, the acid is hydrochloric acid. In another most preferred embodiment, the acid is citric acid. The acid may be provided as pure acid solution, diluted acid solution or as acid- containing food ingredient. Examples of acid-containing food ingredient include citrus juice such as lemon juice, lime juice, orange juice, tangerine juice and the like. In an embodiment, the food product or the beverage may have a total sucrose content of 0 to 40%, preferably 0 to 10wt.%, more preferably 0.5 to 4wt.%. In an embodiment, the food product or the beverage may have a total iron content of at least 2.1 mg per serving. The serving may vary depending on the beverage or the food product. The serving of different beverages or food products is well known and may be determined easily by the person skilled in the art. For example, the serving may be of 200mL for a beverage. For example, the serving may be of 15g for a sauce. For example, the serving may be of 125g for a fermented dairy product. For example, the serving may be of 30g for a dressing. In an embodiment, the food product may be selected from the list consisting of broth, fruit and/or vegetable puree, confectionery product, ice cream, sherbet, culinary cream, sauce, dressing, cheese, fermented dairy product, dairy dessert, petfood product, dairy dessert, nutritional bar, cereal product, fermented cereal-based product, food supplement, nutritional composition, nutritional complete formula, infant nutritional product, nutritional bar, enteral nutritional product, plant-based meat analogue, plant-based cheese alternative, or a mixture thereof. In an embodiment, the beverage may be selected from the list consisting of smoothie, soft drink, water-based beverages, soup, dairy beverage, plant-based milk alternative, coffee, tea, cocoa beverage, flavoured water, soup, mineral water, malt beverage, creamer, fermented dairy beverage, plant-based fermented dairy beverage alternative or a mixture thereof. In an embodiment, the food product or beverage is vegetarian or vegan. In particular, the iron-containing green plant material concentrate is suitable for vegan/vegetarian diet and can be used to fortify food products and beverages which are vegan or vegetarian with iron. In a fifth aspect, the invention relates to a food supplement comprising an iron- containing green plant material concentrate according to the second or the third aspect of the invention. The iron-containing green plant material concentrate of the invention may be used to prepare food supplement that allow to deliver significant amount of iron, for example in human, animal or pet. In an embodiment, the food supplement is provided in the form of capsules, gelatin capsules, soft capsules, tablets, sugar- coated tablets, pills, pastes or pastilles, gums, drinkable solutions or emulsions, syrups or gels. In an embodiment, the food supplement may be a food supplement for use in preventing or treating condition or disease associated with iron deficiency in a subject. In an embodiment, the condition or disease associated with iron deficiency may be selected from the list consisting of iron deficiency anaemia, chronic heart failure or pulmonary arterial hypertension. In this embodiment, the food supplement comprises an affective amount, preferably therapeutically or prophylactic effective amount of iron-containing green plant material concentrate, in particular iron. Further details on the term “therapeutically effective amount” or “prophylactic effective amount” are provided in the sixth aspect of the invention. In an embodiment, the food supplement is vegetarian or vegan. In particular, the iron- containing green plant material concentrate is suitable for vegan/vegetarian diet and can be used to fortify food supplements which are vegan or vegetarian with iron. In a sixth aspect, the invention relates to a cosmetic composition or a pharmaceutical composition comprising an iron-containing green plant material concentrate according to the second or the third aspect of the invention. The iron-containing green plant material concentrate of the invention may be used to prepare cosmetic composition or pharmaceutical composition that allow to deliver significant amount of iron, for example in human, animal or pet. The pharmaceutical composition can be administered for prophylactic and/or therapeutic treatments. In therapeutic applications, compositions according to the invention are administered to a patient already suffering from a disease, as described herein under, in an amount sufficient to cure or at least partially arrest the symptoms of the disease and its complications. An amount adequate to accomplish this is defined as "a therapeutically effective amount". Amounts effective for this will depend on the severity of the disease and the weight and general state of the patient. In prophylactic applications, compositions according to the invention are administered to a patient susceptible to or otherwise at risk of a particular disease. Such an amount is defined to be "a prophylactic effective amount". In this use, the precise amounts again depend on the patient's state of health and weight. In an embodiment, the pharmaceutical composition may be a pharmaceutical composition for use in preventing or treating a condition or disease associated with iron deficiency in a subject. In an embodiment, the condition or disease associated with iron deficiency may be selected from the list consisting of iron deficiency anaemia, chronic heart failure or pulmonary arterial hypertension. In this embodiment, the pharmaceutical composition comprises an affective amount, preferably therapeutically or prophylactic effective amount of iron-containing green plant material concentrate, in particular iron. The pharmaceutical composition of the invention is preferably administered with a pharmaceutically acceptable carrier, the nature of the carrier being adapted for the targeted routes, for example oral routes. The desired formulation can be made using a variety of excipients including, for example, pharmaceutical grades of mannitol, lactose, starch, magnesium stearate, sodium saccharin, cellulose, magnesium carbonate. In a preferred embodiment, the pharmaceutical composition may be a tablet, a capsule, a pill, a solution, a suspension, a syrup, a dried oral supplement, a wet oral supplement, an ointment, an aerosol, a patch, a cream, a gel, a spray, a suppository. In a preferred embodiment, the pharmaceutical composition is a pharmaceutical oral composition. In particular, the pharmaceutical oral composition may be a tablet, a capsule, a pill, a solution, a suspension, a syrup, a dried oral supplement, a wet oral supplement. It will be appreciated that the skilled person will, based on his own knowledge select the appropriate components and galenic form to target the active compound to the tissue/compartment of the body of interest, e.g. the skin, colon, blood, vein, artery, lung, heart, stomach, eyes, kidney or liver, taking into account the targeted route of administration, such as oral route of administration. The cosmetic composition may be a tablet, a capsule, a pill, a solution, a suspension, a syrup, a dried oral supplement, a wet oral supplement, an ointment, a patch, a cream, a gel, a spray. It is also possible to add other cosmetically active ingredients. Excipients or colorants commonly used in cosmetic can also be added to the composition. In a preferred embodiment, the cosmetic composition is a cosmetic oral composition. In particular, the cosmetic oral composition may be a tablet, a capsule, a pill, a solution, a suspension, a syrup, a dried oral supplement, a wet oral supplement. It will be understood that the concept of the present invention may likewise be applied as an adjuvant therapy assisting in presently used medications. Since the iron-containing green plant material concentrate of the present invention may easily be administered together with food material, special clinical food may be applied containing a high amount of the iron- containing green plant material concentrate. It will be clear that on reading the present specification together with the appending claims the skilled person will envisage a variety of different alternatives to the specific embodiments mentioned herein. In a seventh aspect, the invention relates to a method for fortifying a food product or beverage with iron comprising preparing a food product or beverage and adding iron- containing green plant material concentrate according to the second or the third aspect of the invention in the food product or beverage. In an embodiment, the food product may be a food product as provided in the fourth aspect of the invention. In an embodiment, the beverage may be a beverage as provided in the fourth aspect of the invention. The iron-containing green plant material concentrate may be used to fortify food products and beverages with iron, including vegan or vegetarian food products/beverages. The iron-containing green plant material concentrate has good sensory properties and does not impart or impart very limited metallic off taste, when use in beverages or food products. Those skilled in the art will understand that they can freely combine all features of the present invention disclosed herein. In particular, features described for the product of the present invention may be combined with the method or process of the present invention and vice versa. Further, features described for different embodiments of the present invention may be combined. Furthermore, where known equivalents exist to specific features, such equivalents are incorporated as if specifically referred in this specification. Further advantages and features of the present invention are apparent from the figures and non-limiting examples. EXAMPLES Example 1 –Iron concentration process of the invention from dry herbs without acids Dry herbs, in particular dry nettle (Urtica dioica) or dry peppermint A or B (Mentha piperita) or dry thyme A or B (Thymus vulgaris), comprising leaves and stems were ground to a powder. Dry thyme A was sourced from France, while dry thyme B was sourced from Morocco. Dry peppermint A was sourced from France, while dry peppermint B was sourced from Egypt. The powder was mixed with water in a ratio 1:15 (w:v) and the powder was let to hydrate for 5 min to form suspensions. The suspension was then blended for 1 min to obtain a slurry. The obtained slurry was filtered through a 500 µm mesh size filter. The permeate was recovered and subsequentially filtered through a 180 µm mesh size filter. The permeate was recovered and the obtained permeate was heat-treated to reach a temperature of 71 °C for 2 min. After cooling to 4 °C, the permeate was centrifuged at 2500g for 10 min. The precipitate was recovered and formed the iron-containing green plant material concentrate. Optionally, the concentrate can be dried. Example 2- Iron concentration process of the invention from dry herbs in presence of acids Dry herbs, in particular dry peppermint (Mentha piperita), dry nettle (Urtica dioica), or dry thyme (Thymus vulgaris) comprising leaves and stems were ground into powder. The powder (50 g) was mixed with water (700 mL) in a ratio 1:15 (w:v) to prepare suspension, and pure citric (4,5 g, 15,8 g, or 6,1 g anhydrous citric acid for peppermint, nettle, or thyme, respectively) acid or ascorbic acid (16,8 g ascorbic acid for peppermint) or hydrochloric acid (3,6 mL, 15 mL, or 5,3 mL 6 M HCl solution for peppermint, nettle, or thyme, respectively) or malic acid (4,7 g malic acid for peppermint) were added in the suspension to reach a pH of 3.5. After acid addition, the suspension was let for 2 minutes to ensure appropriate hydration of the powder in the suspensions. The suspension was then blended for 2 min to obtain a slurry. The obtained slurry was filtered through a 500 µm mesh size filter. The permeate was recovered and subsequentially filtered through a 180 µm mesh size filter. The permeate was recovered and the obtained permeate was heat-treated to reach a temperature of 71 °C for 2 min. After cooling to 4 °C, the permeate was centrifuged at 2500g for 10 min. The precipitate was recovered and formed the iron-containing green plant material concentrate. Optionally, the concentrate can be dried. Example 3 – formulation of a beverage Citric acid or malic acid or lime concentrate or a mixture of them is added to 500 ml of water to lower the pH to 3.5. Sucrose is added to reach a concentration between 20 and 40 g/L. The iron-containing green plant material concentrate of example 1 or 2 is added to reach an iron content of 2.1 mg of iron. The final pH is adjusted to pH 3. Example 4 – Iron quantification Material and Methods Iron contents of the raw materials (i.e. dry herbs powder obtained after grinding) and the iron-containing green plant material concentrates obtained in either example 1 or 2 were determined by atomic emission spectrometry, using a Microwave plasma atomic emission spectroscopy (MP-AES) 4200 (Agilent, Switzerland). For MP-AES analysis, samples (approx. 100–400 mg) were mineralized in duplicate in a Microwave Digestion System (Mars 6, CEM, USA) using Xpress microwave bombs with 4 mL of 70% HNO3 supra pure quality (Sigma- Aldrich, St. Louis, MO, USA 1 mL of 30% H2O2 (Merck KGaA, (Darmstadt, Germany). Mineral solutions were then transferred to 50 mL Falcon tubes and the volume was adjusted to 20 mL with Milli-Q water. Iron content was measured using external calibration with multi element standards at the wavelength 371 nm. Accuracy of the analysis was checked by analyzing the standard reference materials (SRM 3233, Typical Diet; NIST, MD, USA). Results Figure 1 shows the iron concentration (based on DW) of dry peppermint A, dry nettle, dry thyme A and B and their corresponding iron-containing green plant material concentrates obtained according to the method of example 1. Additionally, the iron content of four commercial extracts of peppermint (2 extracts, Martin Bauer 11000005 Peppermint extract powdered, Martin Bauer 11000192 Peppermint SuperFine), nettle (1 extract, Martin Bauer 15100000 Nettle leaves extract powdered), and thyme (1 extract, Martin Bauer 17100001 Thyme extract powdered) is reported. By dry peppermint, dry nettle and dry thyme, it is understood the together of leaves and stems of the dry plant that were ground into powders before being processed into the concentration process. The concentration process of the invention resulted in a significant increase in iron concentration from 298 ppm in dry peppermint A to 2973 ppm in iron-containing peppermint concentrate A (=iron-containing peppermint A concentrate). The concentration process of the invention resulted in a significant increase in iron concentration from 288 ppm in dry nettle to 1355 ppm in iron-containing nettle concentrate. The concentration process of the invention resulted in a significant increase in iron concentration from 180 ppm in dry thyme A to 1294 ppm in iron-containing thyme concentrate A (=iron-containing thyme A concentrate). With another batch of thyme (i.e. thyme B), the concentration process of the invention resulted in a significant increase in iron concentration from 1903 ppm in dry thyme B to 6142 ppm in iron- containing thyme concentrate B (=iron-containing thyme B concentrate). The commercial water extracts of peppermint, nettle and thyme all exhibit very low iron concentrations, specifically below 165 ppm, showing that the concentration process of the invention has clear advantages in obtaining concentrates with high iron concentrations compared to standard water concentration processes. Example 5 – Quantification of antinutritional factors Material and Methods: Oxalic acid was extracted from the sample with water under mechanical agitation. Oxalic acid was determined by ion chromatography (Dionex ICS-5000, with column Dionex Ion PAC AS16 REFIC Analytical (250 x 2 mm)) coupled to mass spectrometry (SCIEX Triple Quad 5500 with Selexion). Total phenolic content was quantified as follows. Phenolics were extracted by suspending the samples in methanol, shaking them for 1 min every 5 min for 30 min. The samples were then centrifuged (750g, 10 min, 20 °C) and the supernatant recovered. The pellet was reextracted with methanol, centrifuged and the supernatant recovered and pooled with the previous one. The extract (1 mL) was mixed with 15 mL water and 1 mL Folin- Ciocalteu phenol reagent, mixed well and allowed to sit for 6 min. Sodium carbonate solution (3 mL, 20%) was added to each sample and mixed well. The samples were incubated at 30°C for 2 h and then the absorbance was read at 765 nm. Total phenolic content was quantified against a gallic acid calibration curve, therefore the results are expressed as gallic acid equivalent as each phenolic compound was equivalent to one molecule of gallic acid. The phytic acid was measured according to the “phytic acid (phytate) / Total phosphorus” Megazyme kit. This kit enables quantification of free and total phosphorus in the sample by means of colorimetric detection. Total phosphorus is defined as the phosphorus that is derived from phytic acid as well as other sources and is measured after treating sample first with phytase followed by alkaline phosphatase. Free phosphorus, on the other hand, is defined as phosphorus derived from non-phytic acid sources within the sample and is measured without enzymatic treatment from the kit. In short, 1 g of sample was mixed with 20 mL HCl acid (0.66 M) and stirred vigorously for 3 h to form an extract. The extract (1 mL), was centrifuged at 13000 rpm for 10 min and 0,5 mL of the resulting supernatant was neutralised with 0.5 mL NaOH solution (0.75 M). The neutralised sample extract (0.05 mL) was mixed with distilled water (0.60 mL), the provided buffer I (0,20 mL) and a phytase suspension (0.02 mL) for the quantification of total phosphorus. A control sample was prepared by mixing the sample extract (0.05 mL) with distilled water (0.62 mL) and the provided buffer I (0.20 mL) to quantify free phosphorus. Both samples were vortexed and incubated at 40 °C for 10 min. Distilled water (0.02 mL) and provided buffer 3 (0.2 mL) were added to the control, while buffer 3 (0.20 mL) and suspension 4 (ADP, 0.02 mL) were added to the sample for total phosphorus. Samples were vortexed and incubated at 40 °C for 15 min. The reaction was stopped by adding 0,30 mL of trichloroacetic acid (50% w/v). Samples were centrifuged at 13000 rpm for 10 min. The supernatant (1 mL) was used for the colorimetric determination of phosphorus. The samples was mixed with 0.5 mL of color reagent. The color reagent was prepared by mixing 1 part of ammonium molybdate solution (5% w/v) with 5 parts of ascorbic acid (10 % w/v)/sulphuric acid (1 M) solution. After mixing the sample with the color reagent, it was incubated at 40 °C for 1 h and afterwards the absorbance read at 655 nm. Measured absorbance was used to calculate concentration of phosphorus, which was in turn used to calculate concentration of PA. Formula (1) was used to calculate concentration of phosphorus in free phosphorus as well as total phosphorus reactions. mean M × vHCl × F × ΔA c _^^^^^^ _^^^^^^^^^^ = (1) w × v × 10000 cphosphorus = concentration of phosphorus in the sample [g/100g] mean M = mean value of phosphorus standards [μg/ΔAstandard], where M = μg of phosphorus in the standard solution (i.e., 0.5 – 7.5) divided by ΔAstandard (i.e., Astandard X - Astandard 0) vHCl = original sample extract volume [mL] F = dilution factor (in this work, F = 1) ΔAsample = absorbance difference of the sample (i.e., Asample tot – Asample free) w= weight of original sample material [g] v = sample volume used in the colourimetric determination step [mL] (= 1 mL) 10000 = conversion from μg/g to g/100 g Equation (2) is used to convert calculated concentration of bound phosphorus into PA concentration. It assumes that the amount of bound phosphorus measured is exclusively of PA-origin.

c_{PA =} concentration of PA in the sample [g/100g] c_phosphorus = concentration of bound phosphorus in the sample [g/100g] 0.282 = mass fraction of phosphorus in PA The molar ratio between iron and phytic acid was then calculated. Results: Table 1 shows the amount of oxalic acid and phytic acid based on dry weight of the iron-containing peppermint concentrates A and B, the iron-containing nettle concentrate and the iron-containing thyme concentrate A obtained according to the method of example 1. Oxalic acid and phytic contents (ppm) based on dry weight in iron-containing peppermint, thyme and nettle concentrates. Oxalic acid (ppm) Phytic acid (ppm) Iron-containing peppermint A concentrate 9177 1569 ± 314 Iron-containing peppermint B concentrate 971 ± 268 Iron-containing nettle concentrate 2229 1575 ± 461 Iron-containing thyme concentrate A 799 ± 100 Table 1 Figure 2 shows the molar ratio between iron and oxalic acid molar concentrations in dry peppermint A and dry nettle powders and iron-containing peppermint A and nettle concentrates obtained according to the method of example 1. The concentration process of the invention resulted in an increase in the iron to oxalic acid ratio from 0.25 to 0.52, indicating a lower concentration of iron potentially chelated by oxalic acid in the iron-containing peppermint concentrate, and therefore potentially more iron available for absorption. An even greater improvement was observed in the iron to oxalic acid ratio from dry nettle (0.23) to iron-containing nettle concentrate (1,11). Figure 10 shows the total phenolics content (mg gallic acid equivalent/g DW) in in dry peppermint B and dry nettle and iron-containing peppermint B and nettle concentrates obtained according to the method of example 1. The concentration process of the invention resulted in a significant decrease in total phenolics from 47,3 in dry peppermint to 16,4 mg GAE/g DW in iron-containing peppermint concentrate, which suggests a potential decrease in inhibitors of iron absorption (antinutritional factors). A similar trend was observed for nettle; total phenolics was decreased from 8,38 in dry nettle to 0,88 mg GAE/g DW in iron-containing nettle concentrate. These results indicate a lower concentration of iron potentially chelated by phenolic compounds in the iron-containing concentrates, and therefore potentially more available for absorption. Figure 3 shows the molar ratio between iron and phytic acid molar concentrations in dry peppermint A and B, nettle, and thyme A powders and iron-containing concentrates obtained from them according to the method of example 1. The concentration process of the invention resulted in an increase in the iron to phytic acid ratio from 2.2 in dry peppermint A to 7.7 in iron-containing peppermint A concentrate. The concentration process of the invention resulted in an increase in the iron to phytic acid ratio from 6.6 in dry peppermint B to 44 in iron-containing peppermint B concentrate (=iron-containing peppermint concentrate B). The concentration process of the invention resulted in an increase in the iron to phytic acid ratio from 1.3 in dry nettle to 8.9 in iron-containing nettle concentrate. The concentration process of the invention resulted in an increase in the iron to phytic acid ratio from 2.3 in dry thyme to 23 in iron-containing thyme concentrate A. These results indicate a lower concentration of iron potentially chelated by phytic acid in the iron-containing concentrates, and therefore potentially more available for absorption. Example 6 – in vitro digestion to quantify iron bioaccessibility Material and Methods: Briefly, 1 g of iron-containing green plant material concentrates prepared according to the concentration processes of example 1 and 2 were mixed with 10 mL of KCl 5mmol + NaCl 140 mmol pH 2. After adjusting the pH to 2, 0.5 mL of pepsin solution (prepared by dissolving 200 mg pepsin in 10 mL 0.1 M HCl) was added and the samples were incubated at 37 °C for 1 h. After 1 h, the pH was adjusted to 5.5 with 1 M NaHCO3. The volume of the samples was adjusted to 15 mL by adding 6.7 KCl 5 mmol + NaCl 140 mmol. Pancreatin solution (2.5 mL, prepared by adding 87.5 mg pancreatin and 525 mg bile extract to 44 mL 0.1 M NaHCO3) was added, and the samples were incubated at 37 °C for 2 h. An aliquot of the full digesta (2.5 g) was analysed for iron content by MPAES. The rest of the sample was centrifuged at 10000g for 30 min at 4 °C, and 2.5 g of supernatant was analysed for iron content by MPAES. Iron bioaccessibility was defined as: 100 Iron bioaccessibility refers to the fraction of the total amount of iron that is theoretically available for absorption. Results: Figure 4 shows the iron bioaccessibility of iron-containing peppermint concentrates prepared with water according to the concentration process of example 1 or prepared in presence of acid (i.e. citric acid or hydrochloric acid or malic acid or ascorbic acid) according to the concentration process of example 2 from dry peppermint B. The iron bioaccessibility of the different concentrates was compared to the one of an iron salt, in particular iron pyrophosphate. The use of citric acid during the concentration process of the invention significantly increased the iron bioaccessibility (24%) compared to the concentrate prepared with the concentration process of the invention with water in absence of acid (11%) or in presence of another acid such as ascorbic acid (10%). Hydrochloric acid positively impacted the iron bioaccessibility, but to a lesser extent than citric acid, leading to 20% iron bioaccessibility. Malic acid positively impacted the iron bioaccessibility, but to a lesser extent than citric acid, leading to 18% iron bioaccessibility. The iron-containing peppermint concentrate prepared with citric, hydrochloric, or malic acids showed a higher iron bioaccessibility than iron pyrophosphate, a commonly used iron fortificant. Figure 5 shows the iron bioaccessibility of iron-containing nettle concentrates prepared with water (according to example 1) or water in presence of respectively citric acid, and hydrochloric acid (according to example 2). Citric acid and hydrochloric acid positively impacted the iron bioaccessibility of the iron-containing nettle concentrates. Figure 6 shows the absolute amount of bioaccessible iron contained in dry peppermint B, and iron-containing peppermint concentrates prepared with water according to the concentration process of example 1 or water in presence of respectively citric acid, hydrochloric acid, malic acid and ascorbic acid according to the concentration process of example 2, from dry peppermint B. The absolute amount of bioaccessible iron was calculated multiplying the iron content in the sample by the bioaccessibility value. The iron-containing peppermint concentrate prepared with hydrochloric acid has clear advantages compared to dry peppermint as it contains a greater amount of bioaccessible iron (601 ppm in iron- containing peppermint concentrate compared to 288 ppm in dry peppermint). Figure 7 shows the absolute amount of bioaccessible iron contained in dry nettle, and iron-containing nettle concentrates prepared with water according to the concentration method of example 1 or water in presence of respectively citric acid and hydrochloric acid according the method to example 2. The absolute amount of bioaccessible iron was calculated multiplying the iron content in the sample by the bioaccessibility value. The iron-containing nettle concentrates prepared with either water, citric or hydrochloric acid have clear advantages compared to dry nettle as they contain greater amounts of bioaccessible iron (39, 114, 147 ppm in iron-containing nettle concentrate prepared with water, citric acid, hydrochloric acid, respectively, compared to 28 ppm in dry nettle). Figure 8 shows the iron bioaccessibility of iron-containing thyme concentrates prepared with water (according to example 1) or water in presence of respectively citric acid, and hydrochloric acid (according to example 2) from dry thyme B. Citric acid and hydrochloric acid positively impacted the iron bioaccessibility of the iron-containing thyme concentrates. Figure 9 shows the absolute amount of bioaccessible iron contained in dry thyme B, and iron-containing thyme concentrates prepared with water according to the concentration method of example 1 or water in presence of respectively citric acid and hydrochloric acid according the method to example 2 from dry thyme B. The absolute amount of bioaccessible iron was calculated multiplying the iron content in the sample by the bioaccessibility value. The iron-containing thyme concentrates prepared with either citric or hydrochloric acid have clear advantages compared to dry thyme as they contain greater amounts of bioaccessible iron (190, 224 ppm in iron-containing thyme concentrate prepared from dry thyme B with citric acid and hydrochloric acid, respectively, compared to 59 ppm in dry thyme B). Example 7- Peppermint/Thyme beverage An iron-containing peppermint concentrate and an iron-containing thyme concentrate were prepared according to example 1. An iron-containing concentrate blend was prepared by mixing 95% of the iron-containing peppermint concentrate A and the 5% of iron-containing thyme concentrate A. Citric acid of them was added to 500 ml of water to lower the pH to 3.5. Sucrose is added to reach a concentration between 20 and 40 g/L. The iron-containing concentrate blend is added to reach an iron content of 2.1 mg of iron. The final pH is adjusted to pH 3. Example 8 – Sensory data Material and Methods Ten different beverages with same iron content (2,1 mg of iron per 200 mL beverage) were prepared: - Beverage A: beverage prepared according to example 3 with iron-containing peppermint concentrate which was prepared according to the method of example 1. - Beverage B: beverage prepared according to example 3 with iron-containing peppermint concentrate which was prepared according to the method of example 2 with citric acid. - Beverage C: beverage prepared according to example 3 with iron-containing peppermint concentrate which was prepared according to the method of example 2 with hydrochloric acid. - Beverage D: beverage prepared according to example 3 with iron-containing nettle concentrate which was prepared according to the method of example 1. - Beverage E: beverage prepared according to example 3 with iron-containing nettle concentrate which was prepared according to the method of example 2 with citric acid. - Beverage F: beverage prepared according to example 3 with iron-containing nettle concentrate which was prepared according to the method of example 2 with hydrochloric acid. - Beverage G: beverage prepared according to example 3 with iron-containing thyme concentrate A which was prepared according to the method of example 1. - Beverage H: beverage prepared according to example 7. - Beverage I: beverage prepared according to example 3 but the iron-containing green plant material concentrate was replaced by reference curry leaves extract (MoFerrin 21, Biogena). - Beverage J: beverage prepared according to example 3 but the iron-containing green plant material concentrate was replaced by reference iron salt, i.e. iron pyrophosphate^. Beverages A-G and I-J were prepared according to the method provided in example 3 with citric acid as acid (instead of malic acid or lime concentrate). The sensory properties of the different beverages were then assessed monadically by people trained to assess the metallic off-taste perceived in mouth. The intensity of the metallic off-taste was characterized by providing a score from 0 (no metallic off-taste perceived in mouth) to 5 (high metallic off-taste perceived in mouth). Results The beverages of example 3 and example 7 comprising iron-containing green plant material of according to the invention, i.e. beverages A-J have good sensory properties. In particular, no unpleasant metallic off-taste was perceived. Conversely, the beverage K with the reference curry leave extract and the beverage L with iron pyrophosphate have strong and unpleasant metallic off-taste. Hence, the process of the invention allows to provide concentrate and so foods, food supplements and beverages with significant amount of iron while having good sensory properties, in particular limited metallic off-taste. Example 9- Iron concentration process of the invention from fresh herbs without acids Iron-containing nettle, peppermint and thyme concentrates were prepared as in example 1 but with the following adjustment: - dry nettle, dry peppermint and dry thyme were replaced respectively by fresh nettle, fresh peppermint and fresh thyme comprising leaves and stems. - the fresh nettle, fresh peppermint and fresh thyme are not ground to a powder before mixing with water. - the fresh nettle, fresh peppermint and fresh thyme are mixed with water in a ratio 1:18 (w:v). Example 10- Iron concentration process of the invention from fresh herbs with acids Iron-containing nettle, peppermint and thyme concentrates were prepared as in example 2 but with the following adjustment: - dry nettle, dry peppermint and dry thyme were replaced respectively by fresh nettle, fresh peppermint and fresh thyme comprising leaves and stems. - the fresh nettle, fresh peppermint and fresh thyme are not ground to a powder before mixing with water. - the fresh nettle, fresh peppermint and fresh thyme are mixed with water in a ratio 1:18 (w:v). Example 11- Iron concentration process of the invention from duckweed without acids Iron-containing duckweed concentrate was prepared according to the process of example 1 but with the following adjustment: - dry herbs were replaced respectively by fresh whole duckweed, in particular fresh whole Lemna minor. - the fresh whole duckweed is not ground to a powder before mixing with water. - the fresh whole duckweed is mixed with water in a ratio 1:12 (w:v). Example 12- Iron concentration process of the invention from duckweed with acids Iron-containing duckweed concentrate was prepared according to the process of example 2 but with the following adjustment: - dry herbs were replaced respectively by fresh whole duckweed, in particular fresh whole Lemna minor. - The fresh whole duckweed is not ground to a powder before mixing with water. - The fresh whole duckweed is mixed with water in a ratio 1:12 (w:v). Example 13- Iron concentration process of the invention from dry herbs with water in presence of sucrose Iron-containing nettle, peppermint and thyme concentrates were prepared as in example 1 but with the following adjustment: Sucrose was added to the suspension of dry herb powder and water before blending, in a concentration ranging between 1% and 20% wt., preferably 5 to 12% wt. Example 14 – Comparison of the iron concentration process of the invention from dry herbs with acids against another process to concentrate iron reported in RO132538A0. Material and Method: Iron-containing spearmint concentrate was prepared as in example 2, but with the following adjustment: Dry ground spearmint was mixed with water in a ratio 1:10 (w:v) and 3% citric acid was added, resulting in a pH of 3. The suspension was mixed for 10 min at 40 °C. The obtained slurry was filtered through a 200 µm mesh size filter. The permeate was recovered and subsequentially filtered through a 50 µm mesh size filter. The permeate was recovered and centrifuged at 2500g for 10 min. The precipitate was recovered and formed the iron-containing spearmint concentrate, which was freeze-dried. The alternative iron concentration process was executed as reported in the patent RO132538A0. Dry ground spearmint was mixed with water in a ratio 1:10 (w:v) and 3% citric acid was added, resulting in a pH of 3. The suspension was mixed for 10 min at 40 °C. The obtained slurry was filtered through a 200 µm mesh size filter. The permeate was recovered and subsequentially filtered through a 50 µm mesh size filter. The permeate was recovered and water was removed by freeze-drying, to obtain a freeze-dried spearmint permeate. Iron was measured in the iron-containing spearmint concentrate and in the freeze- dried spearmint permeate, as explained in example 4. Results: Ground spearmint had an iron concentration of 335.0 ± 0.6 ppm. Based on the iron quantification results, the iron concentration process of the invention led to an iron- containing spearmint concentrate containing 1652.7 ± 1.5 ppm (based on dry weight). The centrifugation step is crucial to concentrate the iron-containing material, while getting rid of the less iron rich material in the supernatant (measured iron content 30.2 ± 0.1 ppm ppm based on dry weight). Differently, based on the iron quantification results, the iron concentration process of RO132538A0, where there is no centrifugation step but the permeate is directly freeze-dried, led to an iron content of 246.0 ± 0.5 ppm. These results clearly show the advantage of the here presented invention to obtain an iron-concentrated plant material, specifically with an iron content that is at least 2-folds higher than the original green plant material. Although the invention has been described by way of example, it should be appreciated that variations and modifications may be made without departing from the scope of the invention as defined in the claims.

Claims

CLAIMS 1. Process for preparing an iron-containing green plant material concentrate comprising the steps of: a) suspending a green plant material in an aqueous liquid to form a green plant material suspension, b) blending the green plant material suspension to obtain a green plant material slurry, c) applying a physical mean on the green plant material slurry to separate and obtain an iron-containing green plant material concentrate, d) optionally, drying the iron-containing green plant material concentrate.

2. The process according to claim 1, wherein the step c) is performed through filtration and/or centrifugation and/or decantation and/or heat treatment.

3. The process according to any one of the preceding claims, wherein the step c) of applying a physical mean is performed through the steps of: c1) filtering the green plant material slurry to obtain a permeate, c2) optionally, heat-treating the permeate, c3) centrifugating or decanting the permeate to obtain an iron-containing green plant material concentrate.

4. The process according to any one of the preceding claims, wherein the green plant material comes from herb or duckweed.

5. The process according to claim 4 wherein the herb is selected from the group consisting of parsley, coriander, mint, thyme, lemon balm, nettle, sage, oregano, rosemary, basil, dill, chervil, savory or a mixture thereof.

6. The process according to any one of the preceding claims, wherein the green plant material comprises, preferably consists only of leaves.

7. The process according to any one of the preceding claims, wherein the green plant material is dried green plant material and/or fresh green plant material.

8. The process according to any one of the preceding claims, wherein the green plant material is dried green plant material and wherein the dried green plant material is ground to a powder before step a).

9. The process according to any one of the preceding claims, wherein the ratio of plant green plant material to aqueous liquid (w/v) within the green plant material suspension is of 1:3 to 1:20.

10. The process according to any one of the preceding claims, wherein an acid is further added to the green plant material suspension before step b).

11. The process according to claim 10, wherein the acid is selected from the list consisting of hydrochloric acid, citric acid, malic acid, ascorbic acid or a mixture thereof.

12. The process according to any one of claims 2 to 11, wherein the step of filtration c) or c1) is performed with a filter having a mesh of 25 µm to 1000 µm.

13. The process according to any one of the preceding claims, wherein the iron concentration by weight percent is at least 2 times higher, preferably 2 to 10 times higher in the iron-containing green plant material concentrate obtained in step c) or c3) than in the green plant material of step a).

14. The process according to any one of the preceding claims, wherein the molar ratio of iron to oxalic acid is at least 2 times higher, preferably 3 to 10 times higher in the iron- containing green plant material concentrate obtained in in step c) or c3) than in the green plant material of step a).

15. An iron-containing green plant material concentrate which is obtainable or obtained by the process according to any one of claims 1 to 14.

16. An iron-containing green plant material concentrate, which comprises at least 500 ppm iron by dry weight of iron-containing green plant material concentrate.

17. The iron-containing green plant material concentrate of claim 16, which has a molar ratio of iron to oxalic acid of at least 0.3 and/or a molar ratio of iron to phytic acid of at least 5.

18. A food product or a beverage comprising an iron-containing green plant material concentrate according to any one of claims 15 to 17.

19. A food supplement comprising an iron-containing green plant material concentrate according to any one of claims 15 to 17.

20. A cosmetic or a pharmaceutical composition comprising an iron-containing green plant material concentrate according to any one of claims 15 to 17.

21. A method for fortifying a food product or beverage with iron comprising preparing a food product or beverage and adding iron-containing green plant material concentrate according to any one of claims 15 to 17 in the food product or beverage.

22. The food supplement according to claim 19 or the pharmaceutical composition according to claim 20, for use in treating or preventing condition or disease associated with iron deficiency in a subject.