METHOD FOR COATING A POWDER PRESS, IN PARTICULAR FOR THE PRODUCE OF A CAPSULE CONTAINING DRINK POWDER

Description

[0001] The present invention relates to a method for coating a powder compact, in particular for producing a capsule containing beverage powder, which is suitable for preparing a beverage such as cocoa, tea or coffee.

[0002] In recent years, coffee capsules have increasingly been used alongside coffee pods for the preparation of portioned beverages, particularly brewed coffee. Their capsule walls are typically made of stainless steel, aluminum, or plastic. Such capsules allow coffee powder to be stored for extended periods without loss of aroma. Furthermore, such capsules allow for the quick and user-friendly preparation of a coffee portion with the desired flavor. A capsule containing the desired coffee variety is inserted into a specially adapted coffee machine, where hot water is then forced through the capsule to produce brewed coffee. However, such capsules are comparatively expensive, partly due to the capsule material used and the complex production process. Furthermore, such capsules pose environmental concerns.Firstly, the capsules are not recyclable and are usually disposed of as residual waste by consumers after use. Recycling of coffee capsules is therefore practically non-existent, which is particularly worrying for aluminum-based coffee capsules, as aluminum production is very energy-intensive, resulting in a particularly poor carbon footprint for such capsules. Another major disadvantage is that such capsules are not biodegradable and therefore cannot be disposed of biologically. Considering that well over 2 billion coffee capsules are consumed annually in Germany alone, this is a serious problem.

[0003] In order to at least partially circumvent the above problems, capsules made of alternative materials have already been proposed.

[0004] WO 2010 / 006979 A1, for example, discloses capsules filled with coffee or tea and comprising a capsule wall containing water as a structuring component in addition to the capsule contents. However, to form a stable capsule wall, the capsule must be cooled below the freezing point of the structuring component, because if the structuring component's freezing point is exceeded, it melts and moistens the capsule contents. This naturally significantly limits the use of such capsules.

[0005] WO 2009 / 053811 A2 describes a capsule that can contain ground coffee, cappuccino powder, chocolate powder, milk powder, or tea powder. The capsule comprises two half-shells that form the capsule walls. The capsule walls are made of a water-soluble material that dissolves during the brewing process. With this concept, the capsule wall material dissolves during the brewing process and thus becomes part of the prepared beverage, which can have an undesirable effect on the flavor. Furthermore, the production of such capsules is complex and expensive.

[0006] To overcome the aforementioned disadvantages, it has already been proposed in EP 3 115 316 A1 to provide a capsule particularly suitable for producing coffee, which comprises a pressed article made of a powder containing at least one polysaccharide, such as coffee powder, wherein the pressed article is coated with at least one coating layer, wherein the at least one coating layer comprises a cross-linked polysaccharide. Preferably, the coating layer is composed of an alginate and is obtained by immersing the pressed article in an alkali metal alginate solution before the thus-treated pressed article is immersed in an alkaline earth metal salt solution. The alkaline earth metal ions act as cross-linking agents, since they form coordinate or ionic bonds with groups of the alginate.This creates a water-insoluble coating that does not impair the flavor of the beverage produced from the capsule and provides sufficient capsule stability to ensure protection during transport and handling without any significant loss of flavor to the capsule contents. Due to the comparatively high viscosity of alkali metal alginate solution, the coating material adheres poorly to the hydrophobic coffee powder compact. This makes transferring and immersing the powder compact from the alkali metal alginate solution into the alkaline earth metal salt solution difficult. Even when done carefully and using specially designed receptacles and holders, achieving a sufficiently uniform coating thickness on the powder compact is difficult, if not even possible.EP3511266 discloses a method for producing a beverage powder-containing capsule with a compact made of a powder mixture, wherein the compact is coated with a coating layer.

[0007] Proceeding from this, the object of the present invention is to provide a method for coating a powder compact, in particular for producing a capsule containing beverage powder for the portion-wise preparation of beverages from beverage powder, such as cocoa, tea and coffee, with which a coated powder compact with a uniform coating thickness is obtained simply and reliably.

[0008] According to the invention, this object is achieved by a method for coating a powder compact, in particular for producing a capsule containing beverage powder, which comprises the following steps: i) Providing a powder compact made of a powder containing at least one polysaccharide, ii) Providing a container with a container wall made of a perforated material which encloses a cavity, wherein the perforated material is a material having a plurality of small holes regularly arranged in the material, wherein the holes have substantially the same shape and size, wherein the container has an inlet opening for introducing coating liquid into the cavity, iii) Introducing the powder compact into the cavity of the container, wherein the powder compact is smaller than the volume of the cavity, iv) Introducing a coating liquid containing a coating material into the cavity via the inlet opening, v) Immersing the container filled with the powder compact and the coating material into a hardener liquid containing a hardener compound,wherein the viscosity of the hardener liquid is lower than the viscosity of the coating liquid, and vi) removing the container from the hardener liquid and removing the coated powder compact from the container.

[0009] This solution is based on the finding that by using a container with a container wall made of a perforated material enclosing a cavity, wherein the container has an inlet opening for introducing coating liquid, a powder compact can be coated easily and reliably, whereby a uniform thickness of the coating of the powder compact is obtained. Since the powder compact introduced into the cavity of the container in step iii) has a smaller volume than the cavity, and thus the powder compact fits into the cavity, a gap forms between the powder compact and the inside of the container wall made of perforated material delimiting the cavity of the container, which gap can be filled with the coating liquid in step iv).Due to the perforation and the inlet opening, the air initially present in the gap is displaced by the coating liquid, allowing the entire gap to be completely filled with the coating liquid in step iv). Since the powder compact floats on the introduced coating liquid, the powder compact is surrounded by a uniformly thick layer of coating liquid when the gap is completely filled with the coating liquid. By immersing the container filled with the powder compact and the coating material into the hardener liquid, a uniform coating thickness is achieved easily and reliably.Because the hardener liquid has a lower viscosity than the coating liquid, the hardener liquid can quickly and evenly enter the container through the small holes in the perforated material during step v) and thus contact the coating liquid. However, due to its higher viscosity, the coating liquid does not escape from the container through the perforated material. Thus, the process easily and reliably produces a coated powder compact with a uniform coating thickness.

[0010] For the purposes of the present invention, perforated material is understood to mean a material having a plurality of small holes, wherein the holes are regularly arranged in the material and each have at least substantially the same shape and size.

[0011] The present invention is not particularly limited with regard to the polysaccharide-containing material from which the powder compact provided in step i) is composed. Good results are particularly obtained when the powder compact contains, or preferably is composed of, a material selected from the group consisting of coffee, tea, hot chocolate, cocoa, and milk powder. Good results are particularly obtained when the powder compact consists of ground coffee powder.

[0012] For the purposes of the present invention, a powder compact is understood to mean compacted powder. Good results are obtained in particular when the powder compact provided in step i) has been produced by pressing powder, in particular coffee powder, at a pressure of 1 to 100 MPa, particularly preferably at a pressure of 5 to 50 MPa, and most preferably at a pressure of 15 to 30 MPa. This provides sufficient compaction to allow a secure coating of the powder compact and to achieve a good oxygen barrier. At lower pressures, there is insufficient cohesion, and at higher pressures, excessive compaction occurs, which may relax again after removal from the press, which can lead to destruction of the capsules.

[0013] In principle, the powder compact can have any desired shape. The powder compact is preferably spherical. Good results are particularly achieved when the diameter of the spherical powder compact is 1 to 10 cm, preferably 1 to 5 cm, particularly preferably 2 to 4 cm, and most preferably 2.7 to 3.7 cm.

[0014] In accordance with this, it is preferred that (also) the cavity of the container is spherical, i.e. the inner surface of the container is spherical.

[0015] In a further development of the inventive concept, it is proposed that the diameter of the cavity in the container is 0.5 to 10.0 mm, preferably 1.0 to 8.0 mm and particularly preferably 3.0 to 6.0 mm larger than the diameter of the spherical powder compact used.

[0016] According to a particularly preferred embodiment of the present invention, the perforated material from which the container wall is composed is a wire mesh. For the purposes of the present invention, a wire mesh is understood to be a sheet-like structure with uniform holes arranged in a regular pattern, formed by the perpendicular crossing of warp and weft wires. Firstly, wire mesh is comparatively inexpensive and easy to process and shape, and secondly, the holes contained therein are arranged particularly regularly and have the same shape and size.

[0017] Preferably, the porous material, preferably the wire mesh, has holes of such a size or such a mesh size that the more viscous coating liquid does not escape through the perforated material, preferably the wire mesh, from the cavity of the container and thus from the container, but the less viscous hardener liquid enters the container quickly and evenly over the surface of the container through the perforated material, preferably the wire mesh, when the container is immersed in the hardener liquid.

[0018] Good results are obtained in particular when the holes in the porous material of the container wall have a diameter or the wire mesh has a mesh size of 0.01 to 0.30 mm, more preferably from 0.02 to 0.21 mm, particularly preferably from 0.04 to 0.08 mm, very particularly preferably from 0.05 to 0.075 mm and most preferably from 0.058 to 0.068 mm, such as for example about 0.063 mm.

[0019] As described, a wire mesh is preferably used as the porous material for the container wall. The wire mesh is preferably made of steel or stainless steel. In a further development of the inventive concept, it is proposed that the wire mesh have a wire thickness of 0.01 to 0.30 mm, preferably 0.02 to 0.20 mm, particularly preferably 0.03 to 0.10 mm, very particularly preferably 0.04 to 0.06 mm, and most preferably 0.045 to 0.055 mm.

[0020] According to the invention, the container provided in step ii) comprises an inlet opening for introducing coating liquid into the cavity. In order to ensure that the coating liquid can be easily introduced through the inlet opening into the cavity of the container, a further preferred embodiment proposes that a tube firmly connected to the container be arranged above the inlet opening of the container, which tube is preferably arranged with its longitudinal axis radially on the container wall.

[0021] In principle, the pipe can be made of any material, such as the same material as the container, preferably steel or stainless steel. However, the pipe is preferably unperforated.

[0022] In principle, the present invention is not limited with respect to the shape of the tube. The tube can, for example, have a rectangular, square, round, elliptical, oval, or polygonal cross-section. The tube is preferably a rectangular tube or a round tube with a length of 1.0 to 5.0 cm, and preferably 2.0 to 4.0 cm. Good results are obtained in particular with a round tube with an inner diameter of 0.1 to 5.0 mm, preferably 0.5 to 2.5 mm, particularly preferably 0.75 to 1.25 mm, very particularly preferably 0.9 to 1.1 mm, and most preferably 0.95 to 1.05 mm.

[0023] In order to be able to easily insert the powder compact into the container cavity and to easily remove the coated powder compact from the container cavity, it is proposed, in a further development of the inventive concept, that the container be constructed from two halves, which are connected to one another via a connecting element, such as a hinge, and can thus be easily combined to form the closed container. In the case of the preferred spherical design of the container, the container preferably has two half-domes connected to one another via a hinge. Both half-domes preferably have the same dimensions and are each made of the same perforated material.When the two half-domes are precisely placed on top of each other with their equators aligned, they define a spherical cavity, excluding the inlet opening, which is preferably formed in only one of the two half-domes. Good results are particularly achieved when the inlet opening is located at the pole of one of the two half-domes.

[0024] The lower, equator-near region of the two hemispheres can, when viewed in cross-section, also have a slightly different radius of curvature than the upper region.

[0025] In order to facilitate a precise and complete placement of the two half-domes, both half-domes can have an outward-projecting collar at the equator, which surrounds the half-domes in a circular ring.

[0026] In principle, the present invention is not limited with regard to the shape of the inlet opening. The inlet opening can, for example, have a rectangular, square, round, elliptical, oval, or polygonal cross-section. Preferably, the inlet opening has a circular cross-section, with the diameter of the inlet opening preferably being 0.1 to 5.0 mm, more preferably 0.5 to 2.5 mm, particularly preferably 0.75 to 1.25 mm, very particularly preferably 0.9 to 1.1 mm, and most preferably 0.95 to 1.05 mm.

[0027] To enable the simultaneous or parallel coating of multiple powder compacts easily and quickly, the process can also be carried out with a plurality of containers, wherein a container configured as described above is connected in a rack to one or more other containers of the same dimensions. In this way, the plurality of containers can be immersed in a bath of hardener liquid simultaneously in one work step. In this embodiment, the rack preferably comprises 2 to 100, and in particular 5 to 50, containers.

[0028] In principle, the process is not particularly limited with regard to the chemical nature of the coating material contained in the coating liquid and the hardener compound contained in the hardener liquid, as long as the hardener liquid has a lower viscosity than the coating liquid. Examples of suitable coating materials are those selected from the group consisting of starch, cellulose, chitin, carrageenan, agar, and alginates.

[0029] Preferably, the viscosity of the hardener liquid is 0.01 to 100 mPa·s, more preferably 0.1 to 20 mPa·s and most preferably 0.5 to 10.0 mPa·s, such as about 1 mPa·s, whereas the viscosity of the coating liquid is preferably more than 100 to 10,000 mPa·s, more preferably 200 to 5,000 mPa·s and most preferably 300 to 1,000 mPa·s, such as about 500 mPa·s.

[0030] The hardener compound is selected so that it crosslinks the coating material, preferably via i) covalent bonds or ii) via ionic and / or coordinate bonds.

[0031] According to a particularly preferred embodiment of the present invention, alginate is used as the coating material in the process. This has the advantage that a homogeneous coating is formed simply and quickly by crosslinking with alkaline earth metal ions. This is a water-insoluble coating that does not impair the taste of the beverage made from the coated powder compact, such as coffee. Furthermore, this provides sufficient stability for the coated powder compact to ensure protection during transport and handling without any significant loss of flavor. Furthermore, calcium alginate is highly biodegradable. A further advantage is that calcium alginate is an approved food additive with the E number E405, which means it is harmless to health.

[0032] Therefore, it is particularly preferred to use a coating liquid which contains an alkali metal alginate (in particular sodium alginate) as the coating material, and a hardener liquid which contains an alkaline earth metal salt (in particular a calcium salt, such as calcium chloride) as the hardener compound.

[0033] Good results are obtained, for example, when an alkali metal alginate solution, preferably an aqueous 0.5 to 5 wt.% alkali metal alginate solution and particularly preferably an aqueous 0.5 to 5 wt.% sodium alginate solution, is used as the coating liquid, and an alkaline earth metal salt solution, preferably an aqueous 1 to 7 wt.% alkaline earth metal salt solution and particularly preferably an aqueous 1 to 7 wt.% calcium chloride solution, is used as the hardener liquid.

[0034] According to a further particularly preferred embodiment of the present invention, the method comprises the following steps: i) Providing a powder compact made of a powder containing at least one polysaccharide, ii) Providing a container with a container wall made of wire mesh which encloses a cavity, wherein the container has an inlet opening for introducing coating liquid into the cavity, and wherein the wire mesh has a mesh size of 0.01 to 0.30 mm, preferably from 0.02 to 0.21 mm, particularly preferably from 0.04 to 0.08 mm, very particularly preferably from 0.05 to 0.075 mm and most preferably from 0.058 to 0.068 mm, iii) Introducing the powder compact into the cavity of the container, wherein the powder compact is smaller than the volume of the cavity, iv) Introducing a coating liquid containing an alkali metal alginate via the inlet opening into the cavity, v) Immersing the container filled with the powder compact and the coating material into an alkaline earth metal salt containing hardener liquid,wherein the viscosity of the hardener liquid is lower than the viscosity of the coating liquid, and vi) removing the container from the hardener liquid and removing the coated powder compact from the container.

[0035] In all of the aforementioned embodiments, steps i) to vi) can be performed in the order mentioned. It is equally possible to perform step ii) before step i) or simultaneously with it.

[0036] In addition to the above-mentioned steps, the process may further comprise, as step vii), drying the coated powder compact obtained in step vi).

[0037] According to a further preferred embodiment, the thickness of the coating of the dried coated powder compact is between 10 and 600 µm and particularly preferably between 20 and 40 µm.

[0038] The present invention is explained below with reference to figures which illustrate but do not limit the invention.

[0039] Showing: Fig. 1 shows a container suitable for the method according to the invention with a container wall made of a perforated material according to an embodiment of the present invention in the open state. Fig. 2 shows the Fig. 1 Container shown in closed state.

[0040] The one in the Fig. 1The container 10 shown, suitable for use in the method according to the present invention, comprises two half-domes 12, 12', which are connected to one another via a hinge 14. The two half-domes 12, 12' each have the same dimensions and are each formed from the same perforated material, preferably a stainless steel wire mesh. The equators 16, 16' of the two half-domes 12, 12' each have a radially outwardly projecting collar 18, 18', which surrounds the half-domes 12, 12' in a circular ring. At the pole of the upper half-dome 12', an inlet opening 20 is provided, above which a pipe 22 is arranged, which is firmly connected to the container. The two half-domes 12, 12' form the container wall 24.

[0041] In the Figure 1In the open state shown, a powder compact can be easily inserted into the cavity 26 of the container 10 according to method step iii) and a coated powder compact can be easily removed from the cavity 26 of the container 10 according to method step v). By folding the two half-caps 12, 12' together via the hinge 14, the two half-caps 12, 12' can be Figure 2 shown, are brought together with their equators and closed with precision. In this state, the coating liquid can be introduced via the pipe 22 and the inlet opening 20 into the cavity 26 of the container according to process step iv), and the container 10 filled with the powder compact and the coating material can be immersed in the hardener liquid container according to process step v).

Claims

1. Method for coating a powder compact, in particular for producing a capsule containing beverage powder, comprising the following steps: i) Providing a powder compact of a powder containing at least one polysaccharide, ii) Providing a container (10) having a container wall (24) of a perforated material enclosing a cavity (26), the material being a material having a plurality of small holes, the holes being regularly arranged in the material and each having at least substantially the same shape and size, the container (10) having an inlet opening (20) for introducing coating liquid into the cavity (26), iii) placing the powder compact into the cavity (26) of the container (10), wherein the powder compact is smaller than the volume of the cavity (26), iv) introducing a coating liquid containing a coating material into the cavity (26) via the inlet port (20), v) immersing the container (10) filled with the powder compact and the coating material in a hardener liquid containing a hardener compound, the viscosity of the hardener liquid being lower than the viscosity of the coating liquid, and vi) Removing the container (10) from the hardener liquid and removing the coated powder compact from the container (10).

2. The method according to claim 1, characterized in that the powder compact is spherical and made of a powder of a substance selected from the group consisting of coffee, tea, drinking chocolate, cocoa and milk powder by pressing the powder with a pressure of 0.01 to 1.000 MPa, preferably 0.05 to 500 MPa, more preferably 0.1 to 100 MPa, further preferably 0.5 to 100 MPa, still more preferably 1 to 100 MPa, even more preferably 5 to 50 MPa and most preferably 15 to 30 MPa.

3. Method according to claim 1 or 2, characterized in that the container (10) has a spherical cavity (26).

4. A method according to any one of the preceding claims, characterized in that perforated material of the container wall (24) is a wire mesh having a mesh size of from 0.01 to 0.30 mm, preferably from 0.02 to 0.21 mm, more preferably from 0.04 to 0.08 mm, even more preferably from 0.05 to 0.075 mm and most preferably from 0.058 to 0.068 mm.

5. The method according to claim 4, characterized in that the wire mesh is made of stainless steel and has a wire thickness of 0.01 to 0.30 mm, preferably of 0.02 to 0.20 mm, more preferably of 0.03 to 0.10 mm, most preferably of 0.04 to 0.06 mm and most preferably of 0.045 to 0.055 mm.

6. Method according to one of the preceding claims, characterized in that a tube (22) firmly connected to the container (10) is arranged above the inlet opening (20) of the container (10).

7. The method according to claim 6, characterized in that the tube (22) is a rectangular tube (22) or a round tube (22) having a length of from 1.0 to 5.0 cm and preferably from 2.0 to 4.0 cm.

8. The method according to claim 6 or 7, characterized in that the tube (22) is a round tube (22) having an inner diameter of 0.1 to 5.0 mm, preferably of 0.5 to 2.5 mm, more preferably of 0.75 to 1.25 mm, even more preferably of 0.9 to 1.1 mm and most preferably of 0.95 to 1.05 mm.

9. Method according to one of the preceding claims, characterized in that the container (10) comprises two half-calottes (12, 12'), each of the same dimensions and each formed from the perforated material, which are connected via a hinge (14), the half-calottes (12, 12') enclosing a spherical cavity (26) when the two half-calottes (12, 12') are each placed on top of one another with their equator (16, 16') in a snug fit, one of the half-calottes (12, 12') having the inlet opening (20) at its pole.

10. A method according to any one of the preceding claims, characterized in that the inlet opening (20) has a circular cross-section with a diameter of from 0.1 to 5.0 mm, preferably from 0.5 to 2.5 mm, more preferably from 0.75 to 1.25 mm, even more preferably from 0.9 to 1.1 mm, and most preferably from 0.95 to 1.05 mm.

11. Method according to one of the preceding claims, characterized in that the container (10) is connected in a rack with one or more other containers (10) of the same dimensions, so that several powder compacts can be coated simultaneously.

12. A method according to any one of the preceding claims, characterized in that a coating liquid is used which contains a coating material selected from the group consisting of starch, cellulose, chitin, carrageenan, agar and alginates.

13. The method according to any one of the preceding claims, characterized in that a hardener liquid is used which contains a hardener compound which crosslinks the coating material via i) covalent bonds or ii) via ionic and / or coordinative bonds.

14. The method according to one of the preceding claims, characterized in that a coating liquid is used which contains an alkali metal alginate as coating material, and a hardener liquid is used which contains an alkaline earth metal salt as hardener compound.

15. The method according to claim 14, characterized in that an alkali metal alginate solution, preferably an aqueous 0.5 to 5% by weight alkali metal alginate solution and particularly preferably an aqueous 0.5 to 5% by weight sodium alginate solution, is used as the coating liquid, and an alkaline earth metal salt solution, preferably an aqueous 1 to 7 % by weight alkaline earth metal salt solution and particularly preferably an aqueous 1 to 7 % by weight calcium chloride solution, is used as hardener liquid.