Process for supplying magnesium and/or calcium enriched water based beverage and associated manufacturing apparatus

Abstract

The invention relates to a process for producing magnesium and/or calcium-enriched drinking water based beverage, comprising: —preparing a concentrated aqueous solution of magnesium and/or calcium bicarbonate by, a) providing a powder of magnesium and/or calcium compound in a reactor (4); b) adding an aqueous liquid in said reactor; and c) injecting carbon dioxide (CO.sub.2) into said reactor; —adding at least part of the concentrated aqueous solution of magnesium and/or calcium bicarbonate into a flowing circuit comprising an aqueous liquid. The invention also relates to the associated manufacturing apparatus comprising a reactor.

Claims

1. A process for producing a calcium-enriched drinking water based beverage, the process comprising: preparing a concentrated aqueous solution of calcium bicarbonate using an apparatus comprising a closed reactor, a line of an open flow circuit comprising a first outlet line, a first inlet line feeding into the closed reactor, and a second outlet line feeding from the closed reactor through a second inlet line into the line of the open flow circuit, wherein the first outlet line, the first inlet line, and the second outlet line are connected to each other at a three-way junction, the preparing of the concentrated aqueous solution comprises: providing a powder of a calcium compound in the closed reactor, wherein the calcium compound is selected from the group consisting of calcium oxide, calcium hydroxide, calcium carbonate, and mixtures thereof; adding an aqueous liquid from the first outlet line through the first inlet line into the closed reactor; and injecting carbon dioxide into the closed reactor to form the concentrated aqueous solution of calcium bicarbonate, into the open flow circuit comprising the aqueous liquid; and adding at least part of the concentrated aqueous solution of calcium bicarbonate from the closed reactor through the second outlet line, to the second inlet line, and into the line of the open flow circuit, wherein the first inlet line feeding into the closed reactor is common with the second outlet line feeding from the closed reactor.

2. The process according to claim 1 wherein the powder further comprises a magnesium compound selected from the group consisting of magnesium oxide, magnesium hydroxide, magnesium carbonate, and magnesium hydroxide carbonate.

3. The process according to claim 1, comprising measuring the electrical conductivity of the concentrated aqueous solution in the closed reactor.

4. The process according to claim 1, wherein the pressure of carbon dioxide atmosphere in the closed reactor is maintained in the range of 1 atm to 10 atm.

5. The process according to claim 1, wherein the solubility of the calcium compound is increased by increasing the pressure of the carbon dioxide atmosphere in the closed reactor.

6. The process according to claim 1, wherein the closed reactor is fed with the calcium compound using a solid dosing pump.

7. The process according to claim 1, wherein the concentrated aqueous solution of calcium bicarbonate is added into the open flow circuit comprising the aqueous liquid to form the calcium-enriched drinking water based beverage using a liquid dosing pump.

8. The process according to claim 1 wherein the closed reactor is automatically agitated.

9. The process according to claim 2 wherein the concentration of magnesium in the concentrated aqueous solution is between 1 g/l and 25 g/l.

10. The process according to claim 1 wherein the concentration of calcium in the concentrated aqueous solution is between 1 g/l and 75 g/l.

11. The process according to claim 2 wherein the concentration of magnesium in the drinking water based beverage is at least 55 mg/l.

12. The process according to claim 1 wherein the concentration of calcium in the drinking water based beverage is 150 mg/l.

13. The process according to claim 7, wherein a further component is incorporated into the calcium enriched drinking water based beverage through the second inlet line, and the second inlet line is downstream of the liquid dosing pump which adds the concentrated aqueous solution of calcium bicarbonate in the aqueous liquid.

14. The process according to claim 13, wherein the further component is selected from the group consisting of salt, mineral, health-promoting material, and taste or flavor rendering material.

15. The process according to claim 1 further comprising mixing the concentrated aqueous solution of calcium bicarbonate with an agitator within the closed reactor, and mixing the concentrated aqueous solution with water in a static mixer.

16. The process according to claim 1 further comprising keeping the concentrated aqueous solution of calcium bicarbonate under a pressure of a carbon dioxide atmosphere of at least 1 atm to 10 atm in the closed reactor during the process.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) The invention is further described with reference to the following examples. It will be appreciated that the invention as claimed is not intended to be limited in any way by these examples.

(2) Embodiments of the present invention will now be described, by way of examples, with reference to the accompanying figures in which:

(3) FIG. 1 is a schematic view of the reaction process used for producing magnesium-enriched water according to the invention;

(4) FIG. 2 is a schematic view of the equipment for producing magnesium-enriched water according to the invention; and

DETAILED DESCRIPTION

(5) As used in this specification, the words “comprises”, “comprising”, and similar words, are not to be interpreted in an exclusive or exhaustive sense. In other words, they are intended to mean including, but not limited to.

(6) Any reference to prior art documents in this specification is not to be considered as an admission that such prior art is widely known or forms part of the common general knowledge in the field.

(7) At present, both natural mineral and remineralized magnesium-rich waters have a mineralized and bitter taste because of the presence of chloride ions and sulfate ions. It might discourage consumers to buy magnesium-rich waters.

(8) To remove this taste, it is proposed to have insoluble magnesium and/or calcium salts from combinations of oxide/hydroxide/carbonate of magnesium and/or calcium to react with carbon dioxide CO.sub.2 in order to get magnesium and/or calcium-enriched drinking water.

(9) As previously mentioned, the invention relates to a process for producing magnesium and/or calcium-enriched drinking water based beverage using the above described apparatus.

(10) Said process proposes to prepare a concentrated aqueous solution of magnesium and/or calcium bicarbonate and to integrate part of said concentrated solution in an aqueous liquid to form magnesium and/or calcium-enriched drinking water based beverage.

(11) For magnesium enrichment, several magnesium compound such as MgO, Mg(OH).sub.2 and MgCO.sub.3 were tested in laboratory to study their kinetics, chemical feasibility and stability.

(12) In case of calcium enrichment, we propose to use calcium oxide, calcium hydroxide or calcium carbonate.

(13) Among the proposed compounds the laboratory tests have been carried on with Mg(OH).sub.2 as an example.

(14) FIG. 1 shows a schematic view of the reaction process used for producing magnesium-enriched water according to the invention.

(15) The main reaction taking place in the proposed process is the following:
Mg(OH).sub.2+2CO.sub.2=Mg(HCO.sub.3).sub.2

(16) With the following decomposition:
Hydration of CO.sub.2: CO.sub.2+H.sub.2O.fwdarw.H.sub.2CO.sub.3  i
Ionization of H.sub.2CO.sub.3: H.sub.2CO3.fwdarw.H.sup.++HCO.sub.3.sup.−  ii
HCO.sub.3.sup.−.fwdarw.H.sup.++CO.sub.3.sup.2−—  iii
Reaction between H.sup.+ and solid: 2H++Mg(OH)2.fwdarw.Mg2++2H2O-  iv

(17) As shown in FIG. 1, the carbonation starts with the diffusion of CO.sub.2 in water, then CO.sub.2 reacts with water to give carbonic acid; carbonic acid is ionized to give H.sup.+ and HCO.sub.3.sup.−; then H.sup.+ is diffused to the surface of solids which allows the carbonation reaction taking place to give magnesium ions.

(18) Thus there is a diffusion of CO.sub.2 from gas phase GP to liquid phase LP, chemical reaction and then diffusion of H.sup.+ from liquid phase LP to the surface of the compound in the solid phase SP.

(19) In order to avoid forming sediments, CO.sub.2 is always in excess in the reaction and the reaction numbered iii can therefore be neglected.

(20) As can be seen from the above formulas, as the concentration of the concentrated mother solution at the end of the reaction depends only on how many materials were added, it is then easier to control the concentration of the concentrated mother solution.

(21) FIG. 2 schematically represents an apparatus 1 in which is implemented a process for producing magnesium and/or calcium-enriched drinking water based beverage.

(22) Said apparatus comprises an open flow circuit comprising a line 1 of demineralized water comprising a pump 2. Line 1 has an outlet line 3 for feeding a closed reactor 4 in the form of a tank reactor with demineralized water through several valves 5a, 5b, and 5c.

(23) The reactor 4 is fed with demineralized water through inlet line 3′. Outlet line 3 of line 1 corresponds to the inlet line 3′ of reactor 4 but they are presented separately according to the component they are related to.

(24) The reactor 4 is initially fed with pure magnesium hydroxide Mg(OH).sub.2 powder and can be further fed with said magnesium compound by a solid dosing pump forming solid dosing means 6.

(25) The reactor 4 is stirred with an agitator 7 to homogenize the mixture and activate and improve the reaction between the ingredients.

(26) Another object of the agitation is to disperse the gas formed during the reaction. Among various types of agitators, the Rushton turbine, known to the skilled person, is a great choice for dispersing the gas. The pilot tests showed that gas dispersion has a great impact on the reaction rate and that agitating the solution contributes to improve the reaction. The speed agitation should be adapted according to the size of the reactor.

(27) The apparatus also comprises a source 8 of carbon dioxide. Gaseous carbon dioxide is injected into the reactor 4 using feeding line 9 using carbon dioxide injection means 10. The level of carbon dioxide to be fed into the reactor is controlled using control means 11. A recycling carbon dioxide system can further be added.

(28) The apparatus further comprises electrical conductivity measuring means 12 for continuously measuring the electrical conductivity of the solution into reactor 4. Said electrical conductivity measuring means 12 allows measuring the level of magnesium dissolved in the aqueous solution.

(29) If necessary, the electrical conductivity measuring means 12 can be calibrated according to the temperature of the reaction in the reactor so that the effect of the temperature can be “neutralized”.

(30) A regulation unit (not represented) is used to control and manage the feeding of the reactor with the magnesium compound in order to have to required amount of dissolved magnesium in the aqueous solution in the reactor.

(31) The reactor 4 has an outlet line 13 common with outlet line 3 of line 1 and inlet line 3′ of reactor 4 and uses of valves 5a, 5b and 5c when needed.

(32) The outlet line 13 of reactor 4 comprises valve 14 and pump 15.

(33) A least part of the concentrated aqueous solution of magnesium compound is mixed with the demineralized water of line 1. Line 1 comprises an inlet 13′ coming from reactor 4 for the concentrated aqueous solution to be injected in line 1 of the open flow circuit.

(34) Dosing means 16 allows integrating the required quantity of concentrated aqueous solution of magnesium compound in line 1 in order to get a water based beverage with the required magnesium level. Said dosing means 16 can be in the form of electrical conductivity measuring means.

(35) To help mixing the concentrated aqueous solution with the demineralized water, a static mixer 17 is incorporated in the apparatus thereby delivering a magnesium-enriched drinking water based beverage.

(36) The proposed apparatus, line 1 of the open flow circuit further comprises an inlet 18 through which another component 19 is incorporated into the magnesium-enriched drinking water based beverage.

(37) The component 19 is selected from the group consisting of salt, mineral, health-promoting material, and taste or flavor rendering material and is therefore selected according to the need.

(38) The invention also related to a process for producing magnesium and/or calcium-enriched water based beverage in which a concentrated aqueous solution of magnesium and/or calcium bicarbonate made in a stirred reactor 4 is added to aqueous liquid, preferably demineralized water.

(39) The concentrated solution is prepared using a powder of magnesium and/or calcium compound in which aqueous liquid, preferably demineralized water is added under a carbon dioxide atmosphere. The powder contains particles having particle size less than 100 μm. The ingredients in the reactor 4 are agitated and are kept under carbon dioxide atmosphere.

(40) The electrical conductivity of the concentrated aqueous solution is measured, continuously or at regular intervals, using electrical conductivity measuring means 12, and reflects the quantity of magnesium and/or calcium compound dissolved in the concentrated solution.

(41) If needed, the concentrated solution can be further concentrated by adding more of magnesium and/or calcium compound. The reactor 4 is then fed with added magnesium and/or calcium compound using a solid dosing pump 6.

(42) A mentioned, the reactor is kept under carbon dioxide atmosphere, the presence of carbon dioxide at pressures greater than atmospheric pressure gives higher magnesium dissolution rates. Indeed, the solubility of Mg(OH).sub.2 can be improved by increasing the pressure of CO.sub.2, because higher the pressure is, higher the solubility of CO.sub.2 is. It has been estimated that the solubility of Mg(OH).sub.2 can be improved 3 times between a pressure of carbon dioxide of 1 atm and a pressure of carbon dioxide of 10 atm.

(43) Furthermore, in order to avoid waste in carbon dioxide, it is proposed to have the carbon dioxide recycled.

(44) The solution in the reactor is agitated using the agitator 7 to disperse the gas formed during the reaction. Among various types of agitators, the Rushton turbine, known to the skilled person, is a great choice for dispersing the gas. The pilot tests showed that gas dispersion has a great impact on the reaction rate and that agitating the solution contributes to improve the reaction. The speed agitation should be adapted according to the size of the reactor.

(45) Example using Mg(OH).sub.2:

(46) Mg(OH).sub.2 solubility is around 9 mg/L according to the safety data sheet from the supplier.

(47) By making Mg(OH).sub.2 powder react with CO.sub.2 and water in a stirred tank reactor, at the end of the reaction a concentrated solution of 5 g/L of Mg.sup.2+ (12 g/L of Mg(OH).sub.2) which is then in the form of Mg(HCO.sub.3).sub.2 is obtained. Thermodynamically, this concentrated solution is not stable and this salt should precipitate as MgCO.sub.3. However, under CO.sub.2 atmosphere and room temperature (about 25° C.), it is stable at least 3 days which allows us to produce our products before the crystals appear. Therefore, it is important to keep the reactor closed under CO.sub.2 atmosphere. The concentrated solution is next precisely diluted into pure (demineralized) water with a dosing pump. The diluted solution is the final product.

(48) Hence, in a production at industrial scale, the concentrated solution of magnesium and/or calcium compound should be kept under carbon dioxide atmosphere. A mentioned, the concentrated solution prepared in the laboratory is stable under room temperature and CO.sub.2 atmosphere for at least several days.

(49) The new process can also be applied to prepare high concentration solution of Ca(HCO.sub.3).sub.2 from CaCO.sub.3.

(50) With the proposed process and apparatus, the concentration of magnesium in the concentrated aqueous solution is between 1 g/l and 25 g/l. Similarly, the concentration of calcium in the concentrated aqueous solution is between 1 g/l and 75 g/l.

(51) These concentrated solutions easily lead to drinking water based beverage having a concentration of magnesium of at least 55 mg/l and a concentration of calcium of at least 150 mg/l.

(52) The obtained concentrations allows to reach concentrations similar to magnesium and calcium concentration of highly mineralized natural spring waters without the specific taste of these highly mineralized natural spring waters which is a great success.

(53) Although the invention has been exemplified for magnesium enriched drinking water based beverage, the invention can be implemented for calcium enriched drinking water based beverage and for magnesium and calcium enriched drinking water based beverage without departing from the invention.

(54) 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. Furthermore, where known equivalents exist to specific features, such equivalents are incorporated as if specifically referred in this specification.