PREPARATION OF A LYSINATE COMPOUND FROM AN AQUEOUS LYSIN SOLUTION

Abstract

The invention relates to a process for preparing a monolysinate compound (200, 300, 400, 500, 600, 700, 800, 900). The process comprises providing (502) a liquid reaction mixture (810), in which lysine (802) and a metal salt (404) are dissolved; reacting the lysine dissolved in the reaction mixture and the metal salt to form the monolysinate compound; and drying the liquid reaction mixture in order to obtain the monolysinate compound.

Claims

1. Process for preparing a monolysinate compound, which comprises: providing a liquid reaction mixture, in which lysine and a metal salt are dissolved; reacting the lysine dissolved in the reaction mixture and the metal salt to form the monolysinate compound; drying the liquid reaction mixture in order to obtain the monolysinate compound.

2. Process according to claim 1, which comprises providing an aqueous lysine solution; producing the liquid reaction mixture by dissolving the metal salt in the aqueous lysine solution.

3. Process according to claim 1, wherein the monolysinate compound is a compound according to one of the following structural formulae a), b), c) or d), where M represents a metal cation of the metal salt and A represents the anion of the metal salt: ##STR00001##

4. Process according to claim 1, wherein, in the monolysinate compound, exactly one lysine molecule is bonded to exactly one metal atom of the metal salt, the bond being an ionic bond.

5. Process according to claim 1, wherein the metal salt is a metal sulfate, a metal hydroxide or a metal carbonate.

6. Process according to claim 1, wherein the metal of the metal salt is a divalent metal, in particular Mn.sup.2+, Fe.sup.2+, Zn.sup.2+, Cu.sup.2+, Ca.sup.2+, Mg.sup.2+, Co.sup.2+, Na.sup.2+ or Ni.sup.2+.

7. Process according to claim 1, wherein the monolysinate compound is a manganese monolysinate sulfate or an iron monolysinate sulfate.

8. Process according claim 1, wherein the metal salt is a zinc sulfate (ZnSO.sub.4), iron sulfate (FeSO.sub.4) or manganese sulfate (MnSO.sub.4).

9. Process according to claim 1, wherein the liquid reaction mixture is produced by dissolving a metal salt in the aqueous lysine solution in a molar ratio of 1 mol of a metal atom of the metal salt to 1 mol of the lysine.

10. Process according to claim 1, wherein the reaction comprises mechanically mixing the dissolved lysine and the dissolved metal salt at a temperature of at least 60° C., preferably 60° C.-90° C., for at least 15 minutes.

11. Process according to claim 1, wherein the provided aqueous lysine solution has a lysine content of at least 30% by weight, preferably at least 40% by weight of the aqueous lysine solution.

12. Process according to claim 1, wherein the aqueous lysine solution and the liquid reaction mixture are substantially free of chlorides and Cl.sup.− ions, and in particular are substantially free of lysine-HCl salts.

13. Process according to claim 1, wherein the liquid reaction mixture: has a pH of 8.0-8.3 and the metal salt is a manganese sulfate; or has a pH of 6.4-6.8 and the metal salt is an iron sulfate; or has a pH of 5.5-5.9 and the metal salt is a zinc sulfate; or has a pH of 3.6-4.0 and the metal salt is a copper sulfate.

14. Process according to claim 1, wherein the aqueous lysine solution and the liquid reaction mixture: is free of further organic acids if the metal salt is not an iron salt; and/or contains an organic acid, in particular citric acid, if the metal salt is an iron salt.

15. Process according to claim 1, which further comprises: producing granules from the monolysinate compound after or during the drying.

16. Monolysinate compound, produced by a process according to claim 1.

17. Monolysinate compound having the following structural formula, where M represents a metal cation of the metal salt and A represents the anion of the metal salt, according to one of the formulae a), b), c) or d): ##STR00002##

18. Monolysinate compound according to claim 17, wherein the metal salt is a metal sulfate, a metal hydroxide or a metal carbonate, and/or wherein the metal of the metal salt is a divalent metal, in particular Mn.sup.2+, Fe.sup.2+, Zn.sup.2+, Cu.sup.2+, Ca.sup.2+, Mg.sup.2+, Co.sup.2+, Na.sup.2+ or Ni.sup.2+, and wherein the monolysinate compound is preferably free of chlorides and chloride ions.

19. Use of a monolysinate compound according to claim 17 as a feed additive for livestock and pets and/or as a fermentation additive and/or as a fertilizer additive and/or as a food additive and/or as a food supplement.

Description

BRIEF DESCRIPTION OF THE FIGURES

[0067] Embodiments of the invention will be explained in greater detail below purely by way of example, reference being made to the drawings containing said embodiments. In the drawings:

[0068] FIG. 1 shows a general structural formula of L-lysine;

[0069] FIG. 2 shows a general structural formula of a monolysinate compound;

[0070] FIG. 3 shows a specific example of a monolysinate compound according to the general formula of FIG. 2;

[0071] FIG. 4 shows a general structural formula of a further monolysinate compound;

[0072] FIG. 5 shows a specific example of a monolysinate compound according to the general formula of FIG. 4;

[0073] FIG. 6 shows a general structural formula of a further monolysinate compound;

[0074] FIG. 7 shows a specific example of a monolysinate compound according to the general formula of FIG. 6;

[0075] FIG. 8 shows a general structural formula of a further monolysinate compound;

[0076] FIG. 9 shows a specific example of a monolysinate compound according to the general formula of FIG. 8;

[0077] FIG. 10 shows a flowchart of a process for preparing a monolysinate compound as shown for example in FIG. 1;

[0078] FIG. 11 shows a flowchart of a generalized process for preparing a monolysinate compound;

[0079] FIG. 12 shows a container containing a liquid reaction mixture;

[0080] FIG. 13 shows photos of manganese monolysinate granules;

[0081] FIG. 14 shows photos of iron monolysinate granules;

[0082] FIG. 15 shows electron micrographs of iron monolysinate sulfate;

[0083] FIG. 16 shows electron micrographs of manganese monolysinate sulfate;

[0084] FIG. 17 shows an IR spectrum of two monolysinates.

DETAILED DESCRIPTION

[0085] FIG. 1 shows the essential proteinogenic α-amino acid lysine in its natural L-form. According to preferred embodiments of the invention, the “lysine” is to be understood as L-lysine. Lysine contains the groups characteristic of amino acids, namely an amino group 104, a carboxyl group 106, and the residue 102 typical of lysine. The carboxyl group may be negatively charged, so that the lysine is in the form of a lysine anion.

[0086] FIG. 2 shows a general structural formula of a monolysinate compound 200, as can be obtained according to embodiments of the preparation process described here.

[0087] The monolysinate compound 200 contains exactly one lysine molecule per metal atom. It is produced for example from an aqueous solution of lysine and a metal salt, the metal salt consisting of one divalent metal and one divalent anion.

[0088] The carboxyl group is negatively charged, so that the lysine is in the form of a lysine anion. The lysine anion is bonded to the metal cation of the dissolved metal salt via an ionic bond. In particular, in the ionic bond, the metal cation M is the link between the anion A of the metal salt and the lysine anion. In the embodiment shown in FIG. 2, the metal ion M is a doubly positively charged cation and the metal salt anion is a doubly negatively charged anion, one charge of which is saturated by a proton with a charge. The positively charged metal ion may in particular be Mn.sup.2+, Fe.sup.2+, Zn.sup.2+, Cu.sup.2+, Ca.sup.2+, Mg.sup.2+, Co.sup.2+, Na.sup.2+ or N.sup.2+. The anion may for example consist of a sulfate residue or carbonate residue.

[0089] FIG. 3 shows a specific example of a monolysinate compound according to the general formula of FIG. 2, namely a structural formula for manganese monolysinate sulfate 300. The monolysinate compound 200, 300 may contain water of crystallization (water of hydration).

[0090] FIG. 4 shows a general structural formula of a monolysinate compound 400, as can be obtained according to embodiments of the preparation process described here. The monolysinate compound 400 contains exactly one lysine molecule per metal atom. It is produced for example from an aqueous solution of lysine and a metal salt, the metal salt consisting of a divalent metal and two monovalent anions.

[0091] FIG. 5 shows a specific example of a monolysinate compound according to the general formula of FIG. 4, namely a structural formula for manganese monolysinate chloride 500. The monolysinate compound may contain water of crystallization (water of hydration). The compound 500 may be obtained as a reaction product from liquid lysine and manganese chloride MnCl.sub.2. One of the two chloride ions of the MnCl.sub.2 salt attaches to the amine in the amino acid residue of the lysine, creating an ionic bond between the NH3+ group and the chloride anion. The other chloride ion attaches to the divalent manganese cation, creating an ionic bond between the metal cation and the chloride anion. Since the anions and cations of the MnCl.sub.2 salt are in solution before the salt is formed, the two chloride ions may also originate from different MnCl.sub.2 salt monomers. Due to the corrosive property of chlorides, this embodiment with chlorides as anions is possible, but not preferred.

[0092] FIG. 6 shows a general structural formula of a monolysinate compound 600, as can be obtained according to embodiments of the preparation process described here. The monolysinate compound 600 contains exactly one lysine molecule per metal atom. It is produced for example from an aqueous solution of lysine and a metal salt, the metal salt consisting of two monovalent metal atoms and one divalent anion (for example sulfate, carbonate). The compound 600, 700 may contain water of crystallization. The lysine molecule is bonded by its singly negatively charged carboxyl group to the singly positively charged metal ion via an ionic bond. The divalent anion is not part of the monolysinate compound 600, but rather remains as a residue 601 in the reaction solution.

[0093] The structural formula 600 shows the structure obtained for example according to embodiments of the process according to the invention when potassium sulfate (K.sub.2SO.sub.4) is used as the metal salt.

[0094] FIG. 7 shows a specific example of a monolysinate compound according to the general formula 600 of FIG. 6, namely a structural formula for potassium monolysinate 700. The monolysinate compound 700 may contain water of crystallization (water of hydration).

[0095] FIG. 8 shows a general structural formula of a monolysinate compound 800, as can be obtained according to embodiments of the preparation process described here. The monolysinate compound 800 contains exactly one lysine molecule per metal atom. It is produced from an aqueous solution of lysine and a metal salt, the metal salt consisting for example of one monovalent metal atom and one monovalent anion (for example chloride ion). The compound 800, 900 may contain water of crystallization. The lysine molecule is bonded by its singly negatively charged carboxyl group to the singly positively charged metal ion via an ionic bond.

[0096] FIG. 9 shows a specific example of a monolysinate compound according to the general formula 800 of FIG. 8, namely a structural formula for potassium chloride monolysinate 900. The monolysinate compound 900 may contain water of crystallization (water of hydration).

[0097] The free electron pair on the nitrogen atom of the amine group of the lysine residue may accept a proton, as shown by way of example for FIG. 8.

[0098] The monolysinate compound according to embodiments of the invention may be in the form of a monomer or in the form of a polymer comprising a plurality of said monomers. The compound may also be in the form of a mixture of monomer and polymer. By way of example, the monomers may be formed from a compound according to the formula specified in one of FIGS. 2-9. The formation of polymeric lysinate salts may be advantageous since in this way a homogeneous salt crystal lattice and a dense packing of the lysinate salt monomers can be achieved.

[0099] In some embodiments, the metal salt that will be added to the aqueous lysine solution may also contain water of hydration.

[0100] FIG. 10 is a flowchart of a process for preparing a monolysinate compound 200, 300, 400, 500, 600, 700, 800, 900 as shown for example in FIGS. 2-9.

[0101] In a first step 602, an aqueous lysine solution is provided. By way of example, the aqueous lysine solution may be obtained from commercial suppliers. By way of example, aqueous lysine solutions having a lysine content of approximately 50% by weight are available on the market. The aqueous lysine solution has a dark-brown color and an alkaline to slightly alkaline pH. Solutions having such a pH do not corrode or barely corrode steel containers. Aqueous lysine solutions are dissolved in a manner that remains stable over a long period of time and are capable of being stored, for example in plastic or steel tanks. According to some embodiments, it is possible to prepare the aqueous lysine solution by oneself by dissolving the desired quantity of lysine in water or an aqueous metal salt solution. However, the use of an already prepared aqueous lysine solution (without metal salt) saves time since such solutions can already be obtained in ready-made form on the market.

[0102] In particular, the aqueous lysine solution used should be free of chlorides and Cl.sup.− ions and other substances that could corrode steel containers or equipment. This prevents corrosion of the plant, which is undesirable not only with regard to the service life of the plant, but also with regard to the quality of the monolysinate compound to be obtained: in wet chemical processes for forming chelates, which are used in the prior art and in which hydrochloric acid or salts thereof are contained in the reaction mixture, it has been observed that the corrosion of the plant caused by the hydrochloric acid leads to the release of steel stabilizers such as chromium and other heavy metals. The heavy metals released as a result of corrosion may in turn react in an undefined manner with the metal salts dissolved in the reaction solution and may form compounds which are contained in the end product as impurities. Dry processes use mills or other forms of mechanical activation and lead to contamination caused by abrasion of material. Particularly in the context of using the monolysinate compounds as a feed additive, as a food supplement and/or as a plant fertilizer, the introduction of heavy metals such as chromium into the end product is highly undesirable. Many heavy metals are harmful to health and therefore should not be introduced into the metabolism of animals and humans or into arable land. The use of an aqueous lysine solution to prepare monolysinates is therefore not only cost-effective, but also particularly healthy and environmentally friendly since corrosion processes and the associated introduction of undesired heavy metals into the reaction solution are avoided.

[0103] The provided liquid lysine solution is preferably a lysine solution permitted under feed and/or food legislation.

[0104] In an optional step, additional water may be added to the provided aqueous lysine solution in order to dilute the solution. Particularly if the lysine solution is obtained commercially, the concentration may have to be reduced in order to increase the solubility of the metal salts and/or to ensure easy atomization of the reaction solution in a subsequent drying process. It is also possible to add this additional water, if necessary, before, during or after the dissolution of the metal salts in the aqueous lysine solution.

[0105] In a further step 604, a liquid reaction mixture is produced by dissolving a metal salt in the aqueous lysine solution. By way of example, the salt may be added to the lysine solution with constant stirring. By dissolving the metal salt, for example a sulfate, heat is released, as a result of which the prepared solution itself heats up. The metal salt dissolves somewhat more quickly at elevated temperatures. According to embodiments, the temperature of the aqueous lysine solution and/or the liquid reaction mixture is actively increased by heating, for example to a temperature above 30° C., for example above 50° C., furthermore for example above 60° C. The reaction is preferably carried out without active heating in order to save energy, so that the temperature of the reaction mixture increases to approximately 5-15° C. above room temperature during the dissolution.

[0106] The metal salt is preferably added in a molar ratio of metal atom M:lysine of 1:1. The quantity of metal salt required depends on the type of metal salt used and the concentration of the lysine solution.

[0107] By way of example, the liquid reaction mixture may comprise or consist of the following components in order to obtain approximately 1 kg of manganese monolysinate: [0108] 570 g manganese sulfate monohydrate (57%) [0109] 980 g aqueous lysine solution having a lysine content of 50% by weight [0110] 700 g additional water.

[0111] According to a further example, the liquid reaction mixture may comprise or consist of the following components in order to obtain approximately 1 kg of iron monolysinate: [0112] 570 g iron sulfate monohydrate (57%) [0113] 980 g aqueous lysine solution having a lysine content of 50% by weight [0114] 700 g additional water.

[0115] In a next step 306, a chemical reaction takes place between the lysine dissolved in the reaction mixture and the metal salt, so that the monolysinate compound is produced. For this, the dissolved lysine is reacted with the metal salt at temperatures of preferably above 60° C. with constant stirring and is converted into an ionic monolysinate metal salt compound. The stirring process is preferably continued until the starting materials of the reaction mixture have been fully reacted to form the monolysinate compound or until the chemical equilibrium is reached, so that no further increase in the concentration of the monolysinate compound is to be expected. Typically, a period of 20-60 minutes, in particular approximately 25-35 minutes is required for this. As an alternative to stirring, other forms of mechanical mixing of the liquid reaction mixture can also be used, for example shaking, turbulence by means of nozzles, repeated transfer of the liquid mixture into other containers, or the like.

[0116] The chemical reaction of lysine and metal salt to form a monolysinate compound is given by way of example in the following reaction equation for manganese sulfate:

MnSO.sub.4+C.sub.6H.sub.14N.sub.2O.sub.2.fwdarw.[MnC.sub.6H.sub.13N.sub.2O.sub.2]HSO.sub.4

[0117] The corresponding reaction equation for preparing iron monolysinate is as follows:

FeSO.sub.4+C.sub.6H.sub.14N.sub.2O.sub.2.fwdarw.[FeC.sub.6H.sub.13N.sub.2O.sub.2]HSO.sub.4

[0118] The generalized formula is as follows:

MA+C.sub.6H.sub.14N.sub.2O.sub.2.fwdarw.[MC.sub.6H.sub.13N.sub.2O.sub.2]HA

[0119] Here, M represents the metal of the metal salt and A represents the non-metal part of the metal salt. If the charge ratios in the metal salt are taken into account, M represents the metal cation and A represents the corresponding anion.

[0120] By way of example, M may represent manganese Mn.sup.2+, iron Fe.sup.2+, zinc Zn.sup.2+, copper Cu.sup.2+, calcium Ca.sup.2+, magnesium Mg.sup.2+, cobalt Co.sup.2+, sodium Na.sup.2+, potassium K.sup.+ or nickel Ni.sup.2+. By way of example, A may represent a sulfate group SO.sub.4.sup.2−, a hydroxide group or a carbonate group CO.sub.3.sup.2−. In the case of monovalent metals, the stoichiometry must be adjusted accordingly. The monolysinate compound resulting from this reaction mixture according to one embodiment, namely [MnC.sub.6H.sub.13N.sub.2O.sub.2]HSO.sub.4, consists of 17.38% by weight manganese, 30.70% by weight sulfate and 46.22% by weight lysine. The end product, the manganese lysinate complex, contains approximately 5% to at most 10% (percent by weight) water. In the end product, the ratio of percent by weight of lysine to percent by weight of manganese is 1:2.56.

[0121] The monolysinate compound resulting from a reaction mixture according to another embodiment of the invention, namely [FeC.sub.6H.sub.13N.sub.2O.sub.2]HSO.sub.4, consists of 17.60% by weight iron, 30.61% by weight sulfate and 46.10% by weight lysine. The end product, the iron lysinate complex, contains approximately 5% to at most 10% (percent by weight) water. In the end product, the ratio of percent by weight of lysine to percent by weight of iron is 1:2.619.

[0122] Preferred quantity ratios of metal sulfate and lysine solution according to embodiments of the invention can be calculated from the table below for a number of different metal sulfates and depends on the concentration of the lysine solution used. The lysine solution may for example have a lysine content of 50% by weight. The quantities of lysine solution and metal salt are preferably selected such that there is an equimolar ratio of lysine molecules:metal atoms of the metal salt (hereinafter referred to in the tables as an “equimolar mixture”) in the finished reaction solution. It is possible to bring the lysine and the metal salt into solution in other molar ratios in order to prepare the reaction mixture, for example in a molar ratio of 1:1.20 or 1:0.80 instead of a molar ratio of 1:1. However, the reaction products are preferably brought into solution in the ratio below since this means that only a very small stoichiometric residue of starting materials, if any, remains in the reaction solution.

TABLE-US-00002 Weight ratio Metal sulfate:Liquid lysine:water Metal sulfate for an containing 50% by weight [g/mol]:Liquid equimolar lysine lysine [g/mol] mixture Manganese sulfate:liquid lysine 151.00:290.19 1:1.92 Iron hydride tetrahydrate:liquid lysine  198.3:290.19 1:1.46 Iron carbonate:liquid lysine 115.85:290.19 1:2.50 Iron sulfate:liquid lysine 151.91:290.19 1:1.91 Zinc sulfate:liquid lysine 161.45:290.19 1:1.80 Copper sulfate:liquid lysine 156.61:290.19 1:1.85 Copper sulfate monohydrate:liquid lysine 174.61:290.19 1:1.66 Copper sulfate pentaydrate:liquid lysine 249.69:290.19 1:1.16 Magnesium sulfate:liquid lysine 120.37:290.19 1:2.41 Calcium sulfate:liquid lysine 136.11:290.19 1:2.13 Sodium sulfate:liquid lysine 142.04:290.19 1:2.04 Nickel sulfate:liquid lysine 154.76:290.19 1:1.88 Potassium chloride liquid lysine  74.55 290.19 1:3.89 Potassium sulfate:liquid lysine 174.26:290.19 1:1.83

[0123] The molecular weight of 290.19 g/mol is a value calculated for a 50% lysine solution, which is calculated as follows: 1000 g of a pure aqueous 50% lysine solution contain 500 g of lysine, which has a molecular weight of 146.19 g/mol, and 500 g of water, which has a molecular weight of 18.015 g/mol. Therefore, 1000 g of liquid lysine contain 500 g/146.19 g/mol=3.42 mol of lysine and 500 g/18.015 g/mol=27.7 mol of water. The molar ratio of lysine:H2O is therefore 3.42 mol:27.7 mol=1:8.11. This 50% lysine solution therefore contains approximately 8 mol of water per mole of lysine. The hypothetically calculated molecular weight of a 50% aqueous lysine solution is therefore 146.19 g/mol+8.11×18.015 g/mol=292.3 g/mol. The table above gives a mathematically rounded value of 290.19 g/mol, which is obtained when starting from 8 mol of H2O per mole of lysine with a molecular weight of water of around 18 g/mol. If a lysine solution of a different concentration is used, the calculated “hypothetical” molecular weight of liquid lysine in the above table must be adjusted accordingly.

[0124] To prepare manganese sulfate monolysinate, therefore, 1 part by weight of the abovementioned 50% lysine solution is combined with 1.92 parts of manganese sulfate, for example by bringing these 1.92 parts of manganese sulfate into solution in the one part of the lysine solution. The metal salt quantities are calculated in an analogous manner for other metal salts.

[0125] According to further embodiments, different magnesium salts are used to prepare a magnesium salt monolysinate. The table below gives weight ratios for preparing different magnesium lysinates:

TABLE-US-00003 Weight MAGNESIUM ratio SALT for an MAGNESIUM SALT:Liquid [G/MOL]:Liquid equi- lysine:water with a lysine lysine molar content of 50% by weight [g/mol] mixture Magnesium sulfate:liquid lysine 120.37:290.19 1:2.41 Magnesium sulfate heptahydrate:liquid lysine 246.48:290.19 1:1.18 Magnesium carbonate:liquid lysine  84.31:290.19 1:3.44 Magnesium carbonate monohydrate:liquid 102.32:290.19 1:2.84 lysine Magnesium carbonate dihydrate:liquid lysine 120.34:290.19 1:2.41 Magnesium carbonate trihydrate:liquid lysine 138.35:290.19 1:2.10 Magnesium carbonate pentahydrate:liquid 210.40:290.19 1:1.38 lysine Magnesium hydroxide:liquid lysine  58.33:290.19 1:4.97 Magnesium chloride:liquid lysine  95.21:290.19 1:3.05 Magnesium chloride hexahydrate:liquid lysine 203.30:290.19 1:1.43

[0126] It can be seen from the table above that some metal salts are in the form of hydrates. In this case, the water of hydration content must be taken into account when calculating the weight or the quantity of the metal salt to be dissolved. The effect of water of hydration on the mixing ratios of the liquid lysine and the respective metal salt is indicated by way of example for magnesium salts in the table above. The table below contains corresponding weight ratios for calcium salts.

TABLE-US-00004 WEIGHT Calcium RATIO Calcium salt:LIQUID salt FOR AN LYSINE:WATER [g/mol]:LIQUID EQUI- WITH A LYSINE LYSINE MOLAR CONTENT OF 50% BY WEIGHT [G/MOL] MIXTURE Calcium sulfate:liquid lysine 136.11:290.19 1:2.13 Calcium sulfate hemihydrate:liquid lysine 145.15:290.19 1:2.00 Calcium sulfate dihydrate:liquid lysine 172.17:290.19 1:1.69 Calcium sulfate hydrate:liquid lysine 154.16:290.19 1:1.88 Calcium carbonate:liquid lysine 100.09:290.19 1:2.90 Calcium hydroxide:liquid lysine  74.10:290.19 1:3.92 Calcium chloride:liquid lysine 110.98:290.19 1:2.61 Calcium chloride dihydrate:liquid lysine 147.02:290.19 1:1.97 Calcium hydride Tetrahydrate:liquid lysine 183.04:290.19 1:1.59 Calcium hydride hexahydrate:liquid lysine 219.08:290.19 1:1.32

[0127] To prepare boron monolysinates, it is possible for example to use boron carbonate or boron sulfate as the metal salt. To obtain sodium monolysinates, besides sodium sulfate it is also possible to use for example sodium carbonate or sodium carbonate monohydrate or sodium carbonate decahydrate as the metal salt. The tables above are therefore to be understood merely as examples.

[0128] Once the starting materials have fully reacted to form the monolysinate compound, or once the chemical reaction equilibrium has been reached, the liquid reaction mixture is dried in a further step 608 in order to obtain the reaction product contained therein, the monolysinate compound.

[0129] By way of example, the drying may be carried out by means of spray drying (also atomization drying). In the case of spray drying, the fully reacted or equilibrated reaction mixture is introduced by means of an atomizer into a stream of hot gas, which dries the reaction product contained in the mixture to a fine powder within a very short time (a few seconds to fractions of a second). By way of example, the reaction mixture to be dried is atomized by means of a pressure atomizer (typically 50 to 250 bar depending on the model), a pneumatic atomizer (typically 1 to 10 bar depending on the model) or a rotary atomizer (typically 4000 to 50,000 l/min depending on the model). The total surface area of the liquid is hugely increased in size as a result. The atomized reaction mixture is sprayed into a stream of hot gas, as a result of which, due to the large surface area, the liquid evaporates within a very short period of time and the wet material dries to form a fine powder. Since the energy for the evaporation is provided by the hot gas, spray drying is a so-called convection drying process. The hot gas is preferably air. However, the use of inert gases is also possible.

[0130] The inlet temperature of the hot gas lies in the range of 150-200° C., in particular in the range of 170-190° C. The feed temperature of the fully reacted reaction mixture, a dark-brown solution, preferably lies in the range of 60-80° C. The spray pressure preferably lies in the range from 2.0 to 3 bar, in particular 2.0 to 2.8 bar. The solids content of the sprayed, fully reacted reaction mixture is preferably approximately 40-60%, in particular approximately 45-52%.

[0131] The resulting dried material in powder form can then be separated off and collected. By way of example, a cyclone separator may separate from the air stream the monolysinate powder that has been produced by drying. The spray dryer may be operated either continuously or discontinuously.

[0132] The monolysinate powder particles obtained by spray drying typically have a diameter between 80 μm and 100 μm. According to one embodiment, more than 90%, preferably more than 95% of the monolysinate powder particles have a diameter between 80 μm and 100 μm.

[0133] According to some embodiments of the invention, the dried monolysinate powder particles are agglomerated to form granules in order to improve the powder properties (for example powder flowability, sinking behavior, tendency to create dust). For example, very fine monolysinate powder is fed back into the area of the atomizer in order to promote agglomeration there.

[0134] In some embodiments of the process, the step of drying the fully reacted reaction mixture is carried out in a separate step, which takes place before the step of producing granules from the powder obtained during drying.

[0135] In other embodiments, the monolysinate granules are produced in the course of drying. One example of this process variant is spray granulation, in which first, as in the case of pure spray drying, tiny dry particles are kept in suspension in a processing vessel (“fluidized bed”). The surface of these tiny particles serves as a crystallization nucleus for further small droplets generated by the atomization. In the spray granulation process, therefore, drying and granulation take place in a common process step, which makes it possible to monitor the particle growth and thus also to monitor the particle size and in some cases also the surface structure thereof.

[0136] In the context of this invention, “granules” are a particulate substance, wherein the diameter of at least 95%, preferably at least 97% of the particles lies in the range between 100 μm and 800 μm. The granules preferably have a bulk density of 700-800 g/liter (iron monolysinate: approximately 750 g/l, manganese monolysinate: approximately 760-770 g/l) with a residual moisture content of less than 5%, for example a residual moisture content of 2-3%.

[0137] Processing the monolysinate powder to form granules has a number of advantages, such as for example the reduced tendency to create dust, improved ease of handling, better flowability, a reduced tendency to form clumps, and the advantage of easier metering, at least in embodiments in which the granules are “stretched” using fillers or additives in order thus to achieve a lower concentration of the monolysinate compound per unit volume.

[0138] In some applications, however, it is advantageous to expel the dried monolysinate powder directly and process it further since, due to the large specific surface area of the powder, the spray-dried powder dissolves more quickly in water than the corresponding granules.

[0139] The monolysinate compound produced using the process described here typically contains water of crystallization. By way of example, the monolysinate compound [MnC.sub.6H.sub.13N.sub.2O.sub.2]HSO.sub.4 contains approximately 5% of its weight in water of crystallization.

[0140] The monolysinate compound obtained according to the process described here has the advantage that it is particularly pure, that is to say is largely free of impurities that are either already contained in the starting materials or are introduced in the course of processing. In particular, the introduction of heavy metals from corroded steel containers is avoided. The process is cost-effective and can be carried out in a short period of time since use can be made of aqueous lysine solutions that are already commercially available.

[0141] The monolysinate compound thus obtained may be used in a variety of ways: Lysine is one of the limiting amino acids and is used for the synthesis of nucleic acids, for metabolizing carbohydrates, and is important for producing antibodies, hormones and enzymes. In many organisms, in particular including livestock, lysine improves the nitrogen balance, increases the secretion of digestive enzymes, promotes the transport of calcium in the cells, and generally leads to a better state of health, to better digestion of food, and to improved performance. The physiological efficacy of the trace elements added to the feed can be increased by incorporating these trace elements (metals) in the monolysinate compound, so that overall fewer metal salts or metal compounds have to be added to the feed, thereby also reducing the ingress of corresponding metals into rivers and fields via animal excretions.

[0142] One field of use of the monolysinate compound described here according to embodiments of the invention is therefore the use thereof as a component of animal feed, for example as part of a trace element mixture which is used as a food supplement or feed supplement for livestock and pets.

[0143] The monolysinate compound may also be used as an ingredient in plant fertilizer. A number of positive effects of the monolysinate compound described here have been observed in plant fertilization, including an increase in the leaf absorption of trace elements such as iron, manganese, zinc, copper, calcium and magnesium. Lysine, which is taken up by a plant in the form of the monolysinate compound, strengthens the plant's immune system and stimulates chlorophyll synthesis.

[0144] FIG. 11 shows a flowchart of a generalized process for preparing a monolysinate compound 200, 300, 400, 500, 600, 700, 800, 900 as shown for example in FIGS. 2-9. In step 702, the liquid reaction mixture already mentioned in the description of FIG. 10 is produced, it being left open as to whether, as shown in FIG. 10, first a liquid lysine solution is provided, in which the metal salt is then brought into solution, or whether first lysine is brought into solution in an aqueous solution, in which the metal salt is already dissolved in the desired quantity, or whether lysine and metal salt are brought into solution in water simultaneously. All these variants can be used to arrive at the liquid reaction mixture. The lysine and/or metal salt are preferably brought into solution at elevated temperatures of at least 30° C. since this accelerates the dissolution process. As already described, step 704 of chemically reacting the dissolved starting materials to form the monolysinate preferably takes place at temperatures in the range of 60° C.-90° C. with constant stirring over a period of typically 20-60 minutes, for example 25-35 minutes. The fully reacted solution can then be dried 706 to obtain the monolysinate, and may optionally also be granulated.

[0145] FIG. 12 shows a schematic diagram of a container 806 containing a liquid reaction mixture 810, which is stirred for approximately 30 minutes at a temperature between 60 and 90° C. in order to cause the substances dissolved therein to react. The reaction mixture 810 is water in which on the one hand lysine 802 and on the other hand a metal salt, for example manganese sulfate 804, are dissolved. In the course of the dissolution process, the metal salt dissociates into positively charged metal ions and negatively charged anions, for example sulfate ions. In the course of the chemical reaction taking place in the reaction mixture, these starting materials are converted to a monolysinate compound 200, 300, 400, 500, 600, 700, 800, 900, as shown for example in FIGS. 2-9. The reaction container 806 may be, for example, a steel container having a stirring or other mixing device 808.

[0146] FIGS. 13A and 13B show photos of granules of a manganese monolysinate compound according to the formula [MnC.sub.6H.sub.13N.sub.2O.sub.2]HSO.sub.4 that have been obtained by spray granulation, the manganese monolysinate compound being a hydrate.

[0147] FIGS. 14A and 14B show photos of granules of an iron monolysinate compound according to the formula [FeC.sub.6H.sub.13N.sub.2O.sub.2]HSO.sub.4 that have been obtained by spray granulation, the iron monolysinate compound being a hydrate.

[0148] FIG. 15 shows electron micrographs of iron monolysinate sulfate granules at different resolutions. FIG. 15A contains, in the black image strip, a white horizontal bar, the length of which corresponds to 100 μm. The granular structure shown in this image depends heavily on the drying and/or granulation process selected in each case. The corresponding bar in FIG. 15B corresponds to 10 μm, and the one in FIG. 15C corresponds to 100 μm. In particular, FIG. 15C clearly shows the surface of the crystal structure of the iron monolysinate sulfate salt, which is fairly independent of the drying or granulation process selected. The surface exhibits numerous craters and round recesses, but also sharp and rather linear break lines.

[0149] FIG. 16 shows electron micrographs of manganese monolysinate sulfate granules at different resolutions. FIG. 16A contains, in the black image strip, a white horizontal bar, the length of which corresponds to 100 μm. The corresponding bar in FIG. 16B corresponds to 10 μm, and the one in FIG. 16C corresponds to 100 μm. In particular, FIG. 16C clearly shows the surface of the crystal structure of the manganese monolysinate sulfate salt. The surface exhibits numerous craters and round recesses, but also sharp and rather linear break lines. Overall, the surface appears somewhat smoother than the surface of the iron lysinate salt in FIG. 15.

[0150] FIG. 17 shows the results of an IR analysis of iron monolysinate and manganese monolysinate. The table below contains stoichiometric aspects of these compounds based on elemental analysis of the corresponding manganese compound. To characterize the composition, the ATR-IR technique was used to record infrared spectra from iron lysinate sulfate and manganese lysinate sulfate prepared by an embodiment of the process according to the invention. This procedure avoids any sample preparation and thus any associated undesired change in the analytes. Both IR spectra (manganese lysinate sulfate spectrum marked with an “x” in several places, iron lysinate sulfate spectrum marked with a circle in several places) are dominated by a band in the region of 1050 wavenumbers, which is typical for IR vibrations of the atoms oxygen and sulfur within a sulfate residue. This band is almost congruent for these two metal compounds. In the region around 1580 cm-1, the expected, characteristic carbon-oxygen stretching vibration .sup.γ.sub.C═O is shown in the form of the carboxylate band of the amino acid lysine used. In the case of the iron compound, this vibration is shifted to a value of 1582 wavenumbers, while in the manganese counterpart it appears at 1575 cm-1. In addition, there are pronounced bands just below 3000 wavenumbers, which are typical for stretching vibrations .sup.γ.sub.C—H C and are to be assigned here in particular to the four methylene units of lysine. Already from infrared spectroscopy, therefore, a metal lysinate sulfate can be seen to be the product actually present in each case. The metal itself can be determined by targeted analysis of the metal content (->LUFA). In contrast to similar known compounds with a chelate character, both products lack the typical bands shifted far into the high-energy region around 3500 cm-1, so that here there is no “chelate” in the true sense of the word, i.e. with coordinative bonding of the α-amino group to the metal cation, but instead classic salts of the amino acid with the metals have been formed with an ionic character.

[0151] For the manganese compound, an additional test was performed in order to ascertain whether the stoichiometric composition, which can be calculated from the detailed elemental analysis (not just C, H or C, H, N analysis with standard determination of the elements carbon, oxygen and nitrogen, but rather in the specific case with the addition of the sulfur and oxygen content), matches the values to be expected. The result can be seen in the table below.

TABLE-US-00005 Calculated expected Calculated expected quantity for manganese quantity for manganese sulfate mono lysinate sulfate mono lysinate (anhydrous), C6H16MnN2O7S, Measured C6H14MnN2O65, 315.20 g/mol quantity [% 297.18 g/mol [% by (monohydrate) [% by Element by weight] weight] weight] C 22.68 24.25 22.86 H 5.29 4.75 5.12 Mn 16.6 18.49 17.43 N 8.97 9.43 8.89 O 31.45 32.30 35.53 S 10.55 10.97 10.17 Free water 4.1 Total sum 99.64% 100% 100%

[0152] The measured percentages by weight of the quantitatively determined elements carbon, hydrogen, nitrogen, oxygen and sulfur (CHNOS analysis), in conjunction with the LUFA metal analysis, show that a manganese sulfate monolysinate (synonym: manganese monolysinate sulfate) can in fact be inferred. However, this is not in anhydrous form, but rather is in the form of a monohydrate with one equivalent of water of crystallization (see right-hand column of the table).

[0153] The stoichiometric ratio, whereby one divalent metal cation forms a basic unit with one lysinate anion and a sulfate, does not necessarily indicate the monomeric character, that is to say a 1:1:1 compound (possibly plus water of crystallization). Instead, oligomeric structures based on a plurality of said basic units are in principle also conceivable, as shown for example in FIG. 8. In the case of an oligomeric monolysinate, the anions of the metal salt, that is to say for example the sulfate residues, may act as links (that is to say for example in the form of SO.sub.4.sup.2− anions), whereas in the case of a monomeric structure a valence of the SO.sub.4.sup.2− anion is saturated with a hydrogen atom or proton.

LIST OF REFERENCE SIGNS

[0154] 100 structural formula of L-lysine [0155] 102 amino acid residue of the amino acid lysine [0156] 104 amino group of the amino acid lysine [0157] 106 carboxyl group of the amino acid lysine [0158] 200 general structural formula of a monolysinate compound [0159] 300 example of a monolysinate according to FIG. 2 [0160] 400 general structural formula of a monolysinate compound [0161] 500 example of a monolysinate according to FIG. 4 [0162] 600 general structural formula of a monolysinate compound [0163] 602-608 steps [0164] 700 example of a monolysinate according to FIG. 6 [0165] 702-706 steps [0166] 800 general structural formula of a monolysinate compound [0167] 802 lysine molecule [0168] 804 manganese sulfate [0169] 806 reaction ratio [0170] 808 stirring device [0171] 810 liquid reaction mixture [0172] 900 example of a monolysinate according to FIG. 8