Method for producing compostable beverage capsules

Abstract

The present invention relates to a method for producing a capsule with a coating for preparing a beverage by introducing water, the method comprising the steps of: (i) providing a molded body of a beverage powder or a mixture of beverage powders having a coated or uncoated surface; (ii) contacting at least a portion of the surface of the shaped body, preferably the entire surface, with at least one polysaccharide, at least one crosslinker, and at least one polyol to form a layer; (iii) drying the layer. The layers formed in ii) and iii) are adjusted with a swelling degree of 20% to 900%, preferably 60% to 850%, most preferably 100% to 800% and / or the capsules swell upon contact with water by 0.3% to 6%, preferably 0.5% to 5.5%, most preferably 1.0% to 4.0%.

Description

[Technical field]

[0001] The present invention relates to a method for producing a compostable beverage capsule and to the use of such a capsule, in particular for preparing a beverage from a beverage powder by introducing water into the capsule, having the features of the general concepts of the independent claims. [Background technology]

[0002] The provision of luxury foods such as coffee in capsule form is well known, however, the materials normally used as packaging materials, such as plastic or aluminium (e.g. EP 0 468 079), have the disadvantage that they can only be recycled with great effort and are usually not compostable.

[0003] Biodegradable coffee capsules are known. German Patent Specification No. 10 2018 201 187 describes a capsule made of wood blended with bioplastic. The problem with such capsules made of compostable materials, however, lies in their processing. These capsules can be produced using injection molding techniques, but depending on the material used, it is difficult to ensure dimensional accuracy due to the high fiber content. In particular, the sealing contour, which allows the preparation of the beverage under high pressure, is difficult to form with low tolerances.

[0004] DE 10 2014 000 187 A1 describes another biodegradable capsule made of pressed coffee powder coated with a biodegradable layer. For this purpose, the coffee moulds are preferably coated with liquid cellulose derived from polysaccharides, a polyolemic spacer and a crosslinking agent. However, DE 10 2014 000 187 A1 does not say anything about the extent to which the problem of the sealing contour can be solved in beverage preparations under high pressure.

[0005] WO 2017 / 167624 describes a biodegradable capsule for preparing a beverage from a polysaccharide, the capsule being coated with a coating layer of a cross-linked polysaccharide. Summary of the Invention [Problem to be solved by the invention]

[0006] Therefore, the object of the present invention is to overcome the drawbacks of the prior art. In particular, it is intended to provide a method for manufacturing capsules for preparing beverages, which provides capsules with improved sealing even in compostable materials. It is also an object of the present invention to provide capsules made of compostable materials in various sizes and shapes. [Means for solving the problem]

[0007] This problem is solved by the methods and devices defined in the independent claims. Further embodiments result from the dependent claims.

[0008] A first aspect of the invention relates to a method for producing a capsule having a coating for preparing a beverage from a beverage powder by introducing water, the method comprising the steps of: (i) providing a molded body of a beverage powder or a mixture of beverage powders having a coated or uncoated surface; (ii) contacting at least a portion of the surface of the shaped body, preferably the entire surface, with at least one polysaccharide, at least one crosslinker, and at least one polyol to form a layer; (iii) drying the layer.

[0009] The layers formed in steps ii) and iii) are adjusted with a swelling degree of 20% to 900%, preferably 60 to 850%, most preferably 100% to 800%, and / or the capsules swell on contact with water by 0.3 to 6%, preferably 0.5 to 5.5%, most preferably 1.0 to 4.0%, and / or the capsules, in particular after rinsing with water, show a maximum swelling rate in a breaking strength test of at least 15%, in particular at least 20%, preferably at least 25%, particularly preferably at least 30%, in the direction transverse to the pressing direction.

[0010] According to the present invention, a "molded body" is understood to be a core material compressed under pressure. According to the present invention, it is advantageous to provide the core material of the capsule as a shaped body, when the core material is at least partially coated with a coating according to the present invention by dipping, coating or spraying so that it does not collapse during the coating process. It is therefore preferred that the core material has a certain strength. This can be achieved by carrying out the compression of the core material at a compression pressure in the range of 1 to 100 MPa, preferably 5 to 50 MPa, such that the resulting shaped body has a strength in the range of 3 to 120 N, preferably 5 to 60 N.

[0011] The compression pressure applied to produce the shaped body depends on the properties of the core material, in the case of coffee powder, for example the grinding, roasting degree and moisture content of the powder. In particular in the case of coffee powder, it can be observed that powders with a lower fat or oil content, for example decaffeinated coffee powder, require higher compression pressures to achieve a stable shaped body.

[0012] The strength of the compacts is determined by placing them between the two plates of a compression-tensile tester (e.g. equipped with an Xforce P load cell from Zwick / Roell) and determining the force required to crush the compacts. This method is also described on page 3 of WO 2008 / 123775.

[0013] The degree of swelling is calculated from the difference between the wet weight of the coating and the dry weight of the coating according to the following formula:

[0014] SW = [(wet weight – dry weight) / dry weight] · · 100%. The degree of swelling is determined as follows.

[0015] A film is prepared from at least one polysaccharide, at least one polyol, and at least one crosslinker. The film is dried to constant weight at 35°C and 50% rH for 120-140 hours, punched into circles (d=2.5 cm), and the dry weight is determined. The dried film is then immersed in deionized water for 6 hours, patted dry, and the wet weight is determined.

[0016] The expansion of the capsules when in contact with water is determined as follows. The capsule diameter in the dry state is determined using a caliper gauge. The exact measurement points are marked. The capsule is then immersed in hot water at 90°C. After 60 seconds, the capsule is removed and tapped dry. The diameter is then determined again at the markings and the expansion rate is determined.

[0017] The maximum expansion rate of the capsule in the breaking strength test is determined as follows. For the breaking strength test, the capsule is placed between two parallel plates of a compression-tensile testing machine (for example equipped with an Xforce P load cell from Zwick / Roell). The capsule is aligned in the center of the lower plate in the removal direction or in the compression direction in the case of rotationally symmetrical shaped bodies, for example with a spherical or cubic shape. The plates have a diameter at least 50% larger than the maximum capsule diameter. The parallel plates are moved together slowly and a force path diagram is recorded. Concurrent with this crack or break, a drop in force is observed. When the measured force falls below a force drop threshold of 40%, the breaking strength test is terminated. The maximum force measured without damage to the shell is output as the breaking strength. In the case of multi-layer shells, damage or tears penetrating the shell to the core material are understood as damage to the shell. At the same time, the expansion of the capsule is recorded in a direction transverse to the pressing direction, i.e. parallel to the plates. The recording of the transverse expansion is recorded visually. Any flanges of the capsule shell are not taken into account when recording the expansion. The expansion is recorded in two mutually perpendicular directions. An average value is formed from the two measurements. The maximum expansion across the pressing direction is determined at the maximum force without damage, i.e. the breaking strength. If the capsule is not damaged at a force of 600N, the maximum expansion is determined at a force of 600N.

[0018] Depending on the design of the shell, its deformability can be influenced by wetting or rinsing with water. For example, before carrying out the breaking strength test, the capsule can be immersed in a water bath at a temperature of 75°C for 5 seconds and kept underwater. The water is decompressed during this process. The capsule is in a wet state after such wetting or rinsing.

[0019] Such deformability ensures that the capsule can adapt to the shape of the brewing chamber when it is closed or when the brewing liquid, typically hot water, is introduced, that the capsule fits tightly against the walls of the brewing chamber and ensures that the entire amount of brewing liquid can pass through the capsule, and that poor quality of the prepared beverage due to leakage along the outside of the capsule can be prevented.

[0020] The beverage powder is preferably coffee powder, tea powder or milk powder. The beverage powder mixture may be a coffee blend, a coffee substitute blend, a tea blend, a drinking chocolate, a cocoa blend, a latte blend, a milk powder, a fruit milk powder, a vegan milk substitute powder, an instant coffee, a coffee substitute product, a dry soup, and combinations thereof.

[0021] The contact in step ii) is preferably carried out by spraying the polysaccharide, crosslinker and polyol solution, either the separate solutions being sprayed one after the other, or at least one polysaccharide, at least one crosslinker and at least one polyol being mixed and sprayed as a solution mixture. However, the contact with the surface of the shaped body can also be carried out by immersing the shaped body in separate solutions of polysaccharide, crosslinker and polyol, or by immersing the shaped body in a mixture of these compounds. Coating with at least one polysaccharide, at least one crosslinker and at least one polyol or a mixture of these compounds is also possible.

[0022] The drying in step iii) can be carried out at room temperature or at an elevated temperature, but drying at 35° C. and 50% rH for 120 to 140 hours followed by a subsequent heat treatment (hereinafter also referred to as aging) is particularly preferred.

[0023] Alternatively, drying in step iii) can be carried out using a desiccant, such as silica gel, however other hygroscopic desiccants are also contemplated.

[0024] Particularly preferably, the swelling degree of the coating layer is adjusted by heat treatment or curing at 7% rH at a temperature below 100° C., preferably from 25 to 100° C., more preferably from 35 to 80° C., very particularly preferably in the range from 50 to 70° C. Maturation can be carried out for 0.5 to 24 hours, preferably from 1 to 16 hours, particularly preferably from 3 to 9 hours.

[0025] Heat treatment at lower temperatures is economically advantageous and reduces the energy consumption of such manufacturing processes.

[0026] Surprisingly, it was found that the swelling degree of the deposited layer was tunable and decreased with increasing ageing time.

[0027] The adjustable swelling degree allows the capsule to be designed so that it can be easily inserted into common beverage preparation machines and the coating swells on contact with water and thus forms a sealing contour in the machine. This prevents water from flowing through the machine to the sides of the capsule without wetting the beverage powder and thus adversely affecting the quality of the beverage. In particular, these sealing contours withstand the pressure required to prepare the beverage.

[0028] Also, the expansion of the coated capsule allows for deformability allowing for a seal within the brewing chamber that prevents the capsule shape from escaping and the quality of the beverage from being adversely affected.

[0029] The crosslinks of the polysaccharides can be ionic and / or coordinative or covalent. The crosslinks ensure the production of a coating which on the one hand stabilizes the shaped bodies to make them transportable and on the other hand makes them sufficiently elastic to be perforated and allow water to flow through it after contact with water, while allowing the deformation of the coated shaped bodies. The production process offers the possibility to adjust the stability and elasticity so that crack damage during extraction can be avoided. Furthermore, an aromatite coating is produced which preserves the aromatic substances of the shaped bodies, for example coffee, and thus allows the production of beverages with good organoleptic qualities even during longer storage.

[0030] The coating is preferably insoluble in water so that the molded article does not disintegrate even when exposed to hot water for an extended period of time.

[0031] Preferably, the polyol after step iii) is cross-linked with at least one polysaccharide and / or intercalated into the coating.

[0032] In this context, intercalation is understood as non-covalent integration into the network, for example, intercalation can occur due to electrostatic interactions.

[0033] The polyols make it possible to adjust the mechanical properties of the coating in terms of elasticity. Steps (ii) and (iii) may be repeated several times, preferably 2 to 50 times, more preferably 2 to 20 times, most preferably 2 to 10 times, and even more preferably 2 to 5 times.

[0034] By repeating these steps, a coating can be produced from several layers, which allows the thickness of the coating to be adjusted as required.

[0035] At least a portion of the surface of the shaped body may be further contacted with at least one polysaccharide and at least one non-polyol crosslinker, preferably followed by a drying step.

[0036] Thus, coatings can be made from layers with and without polyol, and the properties of the coating can be further tailored to the appropriate needs.

[0037] Preferably, the coating is made of 2 to 50 layers, more preferably 2 to 20 layers, most preferably 2 to 10 layers, and even more preferably 2 to 5 layers.

[0038] The coating can have at least one layer that includes a polyol and at least one layer that does not include a polyol.

[0039] The layer thickness of the coating can be optimally adjusted by the number of layers, and stability and elasticity or flexibility can be adapted to the intended application.

[0040] For example, the shaped body may first be coated with one or more layers of at least one polysaccharide and at least one crosslinker not containing a polyol, and then coated with one or more layers of at least one polysaccharide, at least one crosslinker and at least one polyol, or vice versa.

[0041] A coating consisting of two layers initially containing polyol and an outer layer free of polyol has proven to be particularly advantageous. A coating consisting of one layer containing polyol and an outer layer free of polyol is particularly preferred.

[0042] For example, the shaped body from step iii) may be further contacted with at least one further polysaccharide and at least one cellulose or cellulose derivative.

[0043] Preferably, the individual layers of the coating have a thickness of 30 to 600 μm, preferably 50 to 300 μm, most preferably 50 to 200 μm.

[0044] Preferably, the at least one polysaccharide of the coating is selected from the group comprising alginates, starches, starch derivatives, carrageenans, cellulose, cellulose derivatives, chitin, chitosan, pectin, guar, xanthan gum, locust bean gum, gum arabic, pullulan and agar, and combinations thereof. Preferred polysaccharides are those that have good food compatibility.

[0045] On the one hand, such polysaccharides are readily available and usually of natural origin, and therefore sustainable and readily biodegradable.

[0046] In particular, alginates, such as alkali metal alginates, especially sodium alginate, are preferred.

[0047] Sodium alginate is a food additive and has been approved under the European food additive approval number E 401. It is therefore particularly suitable for the production of beverage capsules in terms of food compatibility.

[0048] The at least one crosslinking agent may be selected from compounds having one or more carbonyl and / or carboxyl functional groups, in particular dialdehydes, diketone compounds and di-, tri- or tetracarboxylic acids, and combinations thereof. The diketone compounds may be 1,2-diketones, preferably 2,3-butanedione, 2,3-pentanedione and 2,3-hexanedione. However, the use of acetone is less suitable.

[0049] The diketone compound is preferably represented by the formula C x H y O2, where x=4-6 and y=6-10. The di- and tricarboxylic acids are preferably of the general formula C x H y O z and preferably has a chain length of at least 4 carbon atoms and at most 6 carbon atoms. Thus, compounds with x=4-6, y=4-10 and z=4-7 are particularly preferred.

[0050] The at least one cross-linking agent is in particular selected from the group consisting of citric acid, fumaric acid, maleic acid, malic acid, tartaric acid and adipic acid, and combinations thereof. These cross-linking agents are registered as food additives (E number) and are therefore particularly suitable for use in food technology and are harmless to health.

[0051] At least one crosslinking agent may also be a salt of a divalent or higher cation, in particular an alkaline earth metal cation, very preferably CaCl2. In this case, crosslinking preferably occurs via ionic and / or coordinate bonds. Such polysaccharides crosslinked via ionic and / or coordinate bonds are particularly easy to prepare and do not impair the biodegradability of the polysaccharides used. Ionic and / or coordinate crosslinking can be achieved, for example, by polysaccharides with anionic groups, such as carboxylate or sulfonate groups.

[0052] It is also possible to choose different cross-linking agents, for example covalent and / or coordinative / ionic cross-linking agents.

[0053] Advantageously, the at least one polyol is selected from the group consisting of aliphatic polyols, preferably ethylene glycol, propanediol, butylene glycol, triethylene glycol, polyethylene glycol, polypropylene glycol, sorbitol, erythritol, xylitol, most preferably glycerol, cyclic polyols, preferably glucose, fructose, mannose, galactose, oligofructose, inulin, isomaltulose, trehalose, sugar substitutes, preferably mannitol, isomalt, maltitol, lactitol, and aromatic polyols, preferably cyanidin, corilagin, digallic acid, tannic acid and gallic acid, and combinations thereof.

[0054] Preferably, the chain length of the polyol is between 2 and 20 carbon atoms, preferably between 2 and 10 carbon atoms, particularly preferably between 3 and 6 carbon atoms. The carbon chain may be linear or branched and separated by heteroatoms, in particular oxygen. Preferably, the polyol has between 2 and 10, preferably between 3 and 6, free hydroxyl (OH) groups.

[0055] The at least one polysaccharide may comprise alginate, the at least one polyol may comprise glycerol, and the at least one crosslinker may comprise citric acid. This combination provides a particularly easy to use coating that further meets the requirements of food compatibility and biodegradability.

[0056] Other particularly preferred combinations that meet food compatibility requirements are described below. The at least one polysaccharide may comprise alginate, the at least one polyol may comprise glycerol, and the at least one cross-linking agent may comprise tartaric acid.

[0057] The at least one polysaccharide may comprise alginate, the at least one polyol may comprise sorbitol, and the at least one crosslinker may comprise citric acid.

[0058] The at least one polysaccharide may include alginate, the at least one polyol may include sorbitol, and the at least one cross-linking agent may include calcium chloride.

[0059] The at least one polysaccharide is preferably provided in an aqueous solution having a concentration of 1.0-5.0% (w / v), preferably 1.0-3.0% (w / v), more preferably 1.0-1.7% (w / v).

[0060] In the case of covalently crosslinked crosslinkers, at least one crosslinker may be provided in an aqueous solution having a concentration of 5-30% (w / v), preferably 10-25% (w / v), and most preferably 15-20% (w / v).

[0061] In the case of ionic and / or coordinative crosslinkers, the crosslinkers may be provided in aqueous solution at a concentration of 2-10 (w / v), preferably 3-7% (w / v), particularly preferably 5% (w / v).

[0062] The at least one polyol is preferably provided in an aqueous solution having a concentration of 0.5-15% (w / v), preferably 0.75-12.5% ​​(w / v), more preferably 0.75-10% (w / v).

[0063] These concentration ranges have the advantage that the solution can be applied well to the mouldings. Especially during spraying, the solution must not be too concentrated to prevent clogging of the nozzles. At the same time, however, the solution must be concentrated enough to allow cross-linking and / or incorporation of the individual components of the coating.

[0064] It is particularly preferred that the at least one polysaccharide and the at least one crosslinking agent are mixed before contacting the surface of the pressed part in step (ii), thus making the process particularly economical.

[0065] It is further preferred to mix the at least one polysaccharide, the at least one polyol and the at least one crosslinking agent prior to contacting the surface of the shaped body in step (ii), thereby providing an economical method of operation.

[0066] It is also possible to contact the surface of the shaped body in step ii) in a subsequent step with at least one polysaccharide, at least one polyol and at least one crosslinking agent.

[0067] The subsequent process has the advantage that individual components can be exchanged without effort.

[0068] Alternatively, it is possible to mix the at least one polysaccharide and the at least one polyol before contacting the surface of the shaped body in step ii) and to immerse the shaped body in a solution comprising at least one crosslinking agent after contacting the mixture.

[0069] Preferably, in step ii) the at least one polysaccharide and the at least one polyol are present in equal weight ratios and the at least one crosslinker is preferably present in 10 times the weight ratio in the aqueous solution, in particular 1.5% (w / v):1.5% (w / v):15% (w / v).

[0070] Providing them in a common solution is particularly preferred, however it is also possible to provide separate solutions as described above.

[0071] Alternatively, in step ii), the at least one polysaccharide, the at least one polyol and the at least one crosslinker are present in a weight ratio of 1.5% (w / v):10% (w / v):5% (w / v).

[0072] Furthermore, fibers, such as cellulose fibers, can be introduced into the coating. The fibers may be present in one or more layers. Preferably, the cellulose fibers are introduced in step (ii), for example by adding them to one or more of the solutions. It is also possible to provide the cellulose fibers in a separate suspension and contact the shaped body with this suspension.

[0073] As cellulose fibers, for example, VITACEL® powdered cellulose LC200 can be used. VITACEL® is a refined, mechanically comminuted cellulose produced by processing alpha-cellulose obtained directly from natural plants. In this process, the molded body can be immersed, for example, in an alginate-polyol-cellulose mixture and then immersed in a calcium chloride bath for gelation. The cellulose fibers LC200 are used at a concentration of 0.2-2% (w / v), preferably 0.5-1.5% (w / v), particularly preferably 0.5-1% (w / v).

[0074] It is also possible to use microcrystalline cellulose (MCG). For example, VIVAPUR MCG 611 FS is suitable for this purpose. The shaped bodies can be immersed, for example, in an alginate-polyol-MCG mixture and then immersed in a calcium chloride bath for gelation. Microcrystalline fiber MCG is used in concentrations of 0.1-5%, preferably 0.5-2.0%, particularly preferably 0.75-1.5%.

[0075] However, it is also possible to use ethylcellulose. For example, ETHOCEL™ Standard 100 Premium is suitable for this purpose. For this purpose, for example, ethanol can be heated to about 75° C. and ethylcellulose can be dissolved therein. The shaped body can then be immersed in the ethylcellulose-ethanol mixture and rolled out onto the paper so that a first layer is placed on the shaped body, followed by at least one further alginate surrounding layer, which can be produced as described above. Ethylcellulose is used in a concentration of 1-30% (w / v), preferably 2-20% (w / v), more preferably 3-10% (w / v).

[0076] The cellulose fibers provide additional stability to the individual layers. Ethyl cellulose acts particularly preferentially as an impregnation layer to prevent moisture absorption into the shaped bodies during coating.

[0077] Surprisingly, it has been found that ethylcellulose prevents moisture from being transported across layers into the pressed product, regardless of the composition of the layers. Therefore, ethylcellulose is suitable as a moisture barrier forming layer for any type of beverage capsule containing powdered beverage, especially for capsules whose coating is derived from an aqueous solution.

[0078] A second aspect of the invention relates to a capsule for preparing a beverage from a beverage powder by introducing water, obtainable by the method described above.

[0079] The present invention also relates to a capsule for preparing a beverage from a beverage powder by introducing water, preferably a capsule as described above. The capsule has a coating of at least one layer, the at least one layer having a swelling degree of 20% to 900%, preferably 60 to 850%, most preferably 100% to 800%, and / or the capsule swells on contact with water by 0.3 to 6.0%, preferably 0.5 to 5.5%, most preferably 1.0 to 4.0%, and / or the capsule, in particular after being rinsed with water, shows a maximum swelling rate in a breaking strength test of at least 15%, in particular at least 20%, preferably at least 25%, particularly preferably at least 30%, in the direction transverse to the pressing direction.

[0080] The capsule coating may have 2 to 50 layers, preferably 2 to 20 layers, very preferably 2 to 10 layers, most preferably 2 to 5 layers. The thickness of the coating can be optimally adjusted by the number of layers, and the stability and elasticity or flexibility can be adapted to the intended application.

[0081] Preferably, the individual layers of the coating have a thickness of 30 to 600 μm, preferably 50 to 300 μm, most preferably 50 to 200 μm. Coating thickness refers to the coating thickness in the dry state.

[0082] The capsule, in particular after being rinsed with water, is capable of absorbing a maximum force in a breaking strength test as described above of at least 25N, in particular at least 50N, preferably at least 100N.

[0083] A maximum force of 25N or more can ensure that the capsule is tightly enclosed in the brewing chamber and deformed without damage. If the capsule is too large for the brewing chamber, for example in one direction, the capsule can still be tightly enclosed between the two brewing chamber halves without damaging the shell and the beverage can be prepared. If the core material is in the form of a moulded body, this can be deformed without damaging the shell and destroying the core material. Optimal extraction is guaranteed.

[0084] Advantageously, the capsule is capable of absorbing a maximum force in the dry state in a breaking strength test of at least 10N, in particular at least 15N, preferably at least 20N.

[0085] "Dry" or "dry state" is understood to mean, unless otherwise defined, that the capsule has not yet come into contact with water or other liquid. This is the state in which the capsule is delivered and inserted by the user into the beverage preparation machine.

[0086] A maximum force of at least 10 N on the capsule in the dry state ensures that the capsule can be gripped by the user without special precautions and that it can be fed into the beverage preparation machine without breaking. The capsules can be packaged and transported in the usual way, i.e. without special precautions.

[0087] The capsules can have a burst pressure of less than 5 bar when wet. This is advantageous as it allows the capsules to dissolve more easily during composting. The capsules are advantageous for composting as they burst under relatively low stress.

[0088] The burst pressure is the internal pressure required to burst the capsule shell. To determine the burst pressure, the capsule is immersed in water with an initial temperature of 75°C for 180 minutes. During the immersion period, the water is allowed to cool to room temperature. The capsule must be completely covered with water. If necessary, it must be kept in water.

[0089] If the capsule core material is a compact, it must be loosened. For this purpose, the capsule undergoes a compression treatment after immersion in water. The capsule is compressed in all three dimensions by 5 mm each at a speed of 50 mm / min. The capsule is rotated 45° and compressed again in all three dimensions by 5 mm. The capsule is then immersed in water at room temperature for a further 120 minutes. The capsule must not be damaged during the compression treatment. If the compact is not loosened, there is a risk that the pressure inside the compact cannot be transmitted to the shell and therefore the burst pressure cannot be accurately determined.

[0090] To determine the burst pressure, a capsule is inserted between two horizontal parallel plates, the upper plate is equipped with a syringe needle. The plates do not apply any pressure to the capsule, only the syringe needle penetrates the capsule shell. The tip of the needle or the needle inlet protrudes from the upper plate at least 0.5 mm beyond the thickness of the wet capsule shell. Room temperature water is introduced into the capsule through the syringe needle and the water pressure is continuously increased and monitored. The water pressure is increased until the capsule shell bursts. The pressure required for rupture is the burst pressure.

[0091] As explained, the increase in the maximum capsule volume when filling the capsule with water at a pressure of up to 18 bar can be at least 15%, in particular at least 20%, preferably at least 25%, particularly preferably at least 30% based on the initial volume without damaging the shell.

[0092] The coating should have a viscosity of less than 50, preferably less than 20, more preferably less than 10, and particularly preferably less than 5 m per 0.21 bar per day. 2 Per cm 3 The capsules may have a surface-conditioned oxygen transmission rate (OTR) in units of 100 / g. The OTR indicates the amount of oxygen diffused through the shell per unit area and unit time. Such an OTR value may ensure that the freshness of the capsules is guaranteed for at least three months after opening the package. Thus, consumers can store the capsules for a period of time in an open package without loss of quality.

[0093] Preferably, the complete capsule is home compostable according to the certification schemes NF T 51-800 and / or AS5810. In this context, "home compostable" means that the material is at least home compostable according to the certification schemes NF T 51-800:2015-11-14 (Plastics - Specification for plastics suitable for home composting) and / or AS5810:2010 (Biodegradable plastics - Biodegradable plastics suitable for home composting). This means at least 90% decomposition (biodegradation) of the material by releasing CO2 within 12 months at a temperature of 25±5°C, as well as at least 90% fragmentation (decomposition) of the material within 6 months at a temperature of 25±5°C. The capsule can therefore be handed over for composting after use. There is no need for separate disposal.

[0094] The capsule may have a circular, in particular spherical, shape. However, it is also conceivable that the shape of the capsule essentially corresponds to other geometric bodies, such as a cube, a rectangular prism, a pyramid, a cylinder, a truncated cone, a cone, a torus, an ellipsoid, etc. It should be noted that any corners and edges are preferably rounded rather than sharp.

[0095] A third aspect of the invention relates to the use of a capsule as described above for preparing a beverage. For this purpose, the capsule can be inserted into a beverage preparation machine. The beverage preparation machine includes a brewing chamber having a mould and a brewing volume for receiving the capsule. The brewing chamber has a piercing means for piercing and introducing water into the capsule and a piercing means for forming an outlet from the capsule. The capsule has a shape and a dry volume before introducing water into the capsule and a wet volume during the introduction of water. During the introduction of water, the wet volume of the capsule increases. The shell of the capsule is configured such that the shape of the capsule is deformable to fit the shape of the brewing chamber without substantial damage to the shell. The maximum wet volume of the capsule during beverage preparation is substantially equal to the brewing volume of the brewing chamber.

[0096] The maximum wet volume is understood to be the maximum volume of the capsule enclosed in the brewing chamber that the capsule absorbs during the introduction of water into the capsule, where, to determine the maximum wet volume, 200 ml of water is introduced into the capsule at a flow rate of 200 ml / min and under a pressure of 6 bar.

[0097] The deformable design of the shell and the matching of the capsule volume with the chamber volume of the brewing chamber during the introduction of water into the capsule can ensure that the capsule and the brewing chamber are optimally matched. For example, the capsule volume does not have to match the volume of the brewing chamber even before the capsule is used. It is also conceivable to use capsules with smaller diameters that are larger than the minimum diameter of the brewing chamber. Similarly, capsules of different sizes can be used with the same brewing chamber. Thus, for example, capsules can be manufactured without adhering to strict tolerances and sacrificing quality. Production costs can be reduced.

[0098] The invention will be explained in more detail below with reference to examples, which are also given below. [Brief description of the drawings]

[0099] [Figure 1] Summary of film thickness determined after drying and as a function of ageing time for examples with citric acid and tartaric acid as crosslinking agents, respectively. [Diagram 2] Summary of the respective swelling degrees as a function of ageing time for examples using citric acid or tartaric acid as crosslinker. [Diagram 3] Film thickness determined as a function of ageing time with CaCl2 as crosslinker. [Figure 4] Swelling degree as a function of ageing time with CaCl2 as cross-linking agent. [Diagram 5] Graphical representation of swelling degree as a function of aging time for Examples 1-7. [Figure 6] Graph of swelling degree as a function of ageing time for Examples 8 and 9. [Figure 7]Graph of swelling degree as a function of aging time for Examples 1-9. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0100] Working Example Example 1 A 1.5% (w / v) sodium alginate solution (4.05 g sodium alginate in 270 mL deionized water) was mixed with 2.025 g glycerol to obtain a concentration of 0.75% (w / v) glycerol. Then, 40.5 g of 1 M citric acid solution was added stepwise and stirred for 20 min. The mixture was poured into a Plexiglas container and dried at 35 °C for 120-140 h until constant weight. Samples were then subjected to different aging times (0, 3, 5, 7, or 9 h) at 70 °C, punched out into circles (d = 2.5 cm) and weighed.

[0101] The samples were then immersed in 30 mL of deionized water for 6 h, patted dry, reweighed, and the degree of swelling was calculated.

[0102] Example 2 A 1.5% (w / v) sodium alginate solution (4.05 g sodium alginate in 270 mL deionized water) was mixed with 4.05 g glycerol to obtain a concentration of 1.5% (w / v) glycerol. Then, 40.5 g of 1 M citric acid solution was added stepwise and stirred for 20 min. The mixture was poured into a Plexiglas container and dried at 35 °C for 120-140 h until constant weight. Samples were then subjected to different aging times (0, 3, 5, 7, or 9 h) at 70 °C, punched out into circles (d = 2.5 cm) and weighed.

[0103] The samples were then immersed in 30 mL of deionized water for 6 h, patted dry, reweighed, and the degree of swelling was calculated.

[0104] Example 3 A 1.5% (w / v) sodium alginate solution (4.05 g sodium alginate in 270 mL deionized water) was mixed with 2.025 g glycerol to obtain a concentration of 0.75% (w / v) glycerol. Then, 40.5 g of 1 M tartaric acid solution was added stepwise and stirred for 20 min. The mixture was poured into a Plexiglas container and dried at 35 °C for 120-140 h until constant weight. Samples were then subjected to different aging times (0, 3, 5, 7, or 9 h) at 70 °C, punched out into circles (d = 2.5 cm) and weighed.

[0105] The samples were then immersed in 30 mL of deionized water for 6 h, patted dry, reweighed, and the degree of swelling was calculated.

[0106] Example 4 Example 4 was carried out similarly to Example 3 using 4.05 g of glycerol to give a 1.5% (w / v) glycerol solution.

[0107] Example 5 Example 5 was carried out similarly to Example 1. However, in this example, 2.025 g of sorbitol was used to give a 0.75% (w / v) sorbitol solution.

[0108] Example 6 Example 6 was carried out similarly to Example 5, except that in this example a 1.5% (w / v) sorbitol solution was used.

[0109] All the examples are again summarized in FIG. 2, showing the determined swelling degrees. To determine the layer thickness, the samples obtained in the examples were punched out with circles with a diameter of 2.5 cm after the drying or aging time and before immersion in water, and the layer thickness was measured with a RUPAC / IP54 digital caliper, with a resolution of 0.01 mm. For each sample, 10 measurements were taken at different points on the sample, from which the average value was calculated. The layer thicknesses thus determined are shown in FIG.

[0110] Example 7 A mixture of sodium alginate (1.5% w / v), cellulose (1% w / v) and sorbitol (10% w / v) was cast into a film and then cross-linked with an aqueous calcium chloride solution (5% w / v). The films were then dried at 35 °C for 120-140 h until constant weight. Samples were then subjected to different aging times (0, 9 or 24 h) at 70 °C, punched out into circles (d = 2.5 cm) and weighed.

[0111] The samples were then immersed in 30 mL of deionized water for 6 h, patted dry, reweighed, and the degree of swelling was calculated.

[0112] The swelling results are shown in FIG. To determine the layer thickness, the samples obtained in Example 7 were punched out with circles with a diameter of 2.5 cm after the drying or aging time and before immersion in water, and the layer thickness was measured with a RUPAC / IP54 digital caliper, with a resolution of 0.01 mm. For each sample, 10 measurements were taken at different points on the sample, from which the average value was calculated. Figure 3 shows the layer thicknesses thus determined.

[0113] Comparative Example Example 8 Example 8 was carried out similarly to Example 1, except that no polyol was used.

[0114] Example 9 Example 9 was carried out similarly to Example 3, except that no polyol was used.

[0115] Capsule Manufacturing Example 10 - Preparation of capsules Capsules were produced from bodies containing three layers of coating according to the above: 5.7 g of coffee powder bodies were first immersed in a 1% aqueous alginate solution containing 10% sorbitol, and then in a 5% calcium chloride solution for 5 seconds.

[0116] The resulting extrusions, after drying the first layer of alginate, sorbitol and calcium ions, were immersed in a second aqueous solution of 1.5% alginate, 10% sorbitol and 1% cellulose, then re-crosslinked and dried in a 5% calcium bath for 5 seconds.

[0117] The resulting moulded body with two layers was immersed in a 1.7% aqueous alginate solution containing 1% cellulose, then crosslinked again in a calcium bath and dried.

[0118] The capsule thus obtained consists of three layers: a first layer of cross-linked alginate and sorbitol; a second layer of cross-linked alginate, sorbitol and cellulose, and - a third layer of cross-linked alginate and cellulose, Shows.

[0119] Figure 5 shows the setting of the swelling degree as a function of aging time. The numbering corresponds to the examples. Graph 1 shows the progression of Example 1, Graph 2 shows Example 2, etc. It was shown that the swelling degree of the coating layer can be adjusted in the presence of polyol and decreases with increasing aging time.

[0120] As can be seen from Figures 2 and 6, the swelling degree of Examples 8 and 9 cannot be adjusted without polyol. From 3 hours of aging, the swelling degree remains almost constant and can no longer be changed. Surprisingly, the presence of polyol shows a significant effect on the setting of the swelling degree.

Claims

1. 1. A method for producing a capsule having a coating for preparing a beverage from a beverage powder by introducing water, the method comprising: (i) providing a molded body of a beverage powder or a mixture of beverage powders having a coated or uncoated surface; (ii) contacting at least a portion of the surface of the shaped body, preferably the entire surface, with at least one polysaccharide, at least one cross-linking agent, and at least one polyol to form a layer; (iii) drying the layer; - the layers formed in ii) and iii) are prepared with a swelling degree of 20% to 900%, preferably 60% to 850%, most preferably 100% to 800%, and / or the capsules are characterized in that they swell on contact with water by 0.3% to 6%, preferably 0.5% to 5.5%, and most preferably 1.0% to 4.0%; method.

2. 2. The method of claim 1, wherein the polyol after step iii) is cross-linked with the at least one polysaccharide and / or intercalated into the coating.

3. 2. The method of claim 1, wherein said adjustment of the swelling degree is carried out by heat treatment at a temperature below 100°C, preferably in the range of 25 to 100°C, more preferably 35 to 80°C, most preferably 50 to 70°C.

4. 2. The method of claim 1, wherein steps (ii) and (iii) are repeated multiple times, preferably 2 to 50 times, more preferably 2 to 20 times, most preferably 2 to 10 times, most preferably 2 to 5 times.

5. 2. The method according to claim 1, wherein the shaped body from step iii) is further contacted with at least one further polysaccharide and at least one cellulose or cellulose derivative.

6. 10. The method of claim 1, wherein the at least one polysaccharide of the coating is selected from the group consisting of alginate, starch, starch derivatives, carrageenan, cellulose, cellulose derivatives, chitin, chitosan, pectin, guar, xanthan gum, locust bean gum, gum arabic, pullulan, and agar, and combinations thereof.

7. 2. The method of claim 1, wherein the at least one polysaccharide is an alginate, preferably present as an alkali metal alginate, in particular sodium alginate.

8. 2. The method of claim 1, wherein the at least one crosslinking agent is selected from compounds having one or more carbonyl and / or carboxyl functional groups, in particular dialdehydes, diketone compounds, and di-, tri-, or tetracarboxylic acids, and combinations thereof.

9. 9. The method of claim 8, wherein the at least one cross-linking agent is selected from the group consisting of citric acid, fumaric acid, maleic acid, tartaric acid, malic acid, and adipic acid, and combinations thereof.

10. The at least one cross-linking agent is a divalent or higher valent cation, particularly an alkaline earth metal cation, most preferably CaCl ２ The method of claim 1, wherein the compound is a salt of

11. 2. The method of claim 1, wherein the at least one polyol is selected from the group consisting of aliphatic polyols, preferably ethylene glycol, propanediol, butylene glycol, triethylene glycol, polyethylene glycol, polypropylene glycol, erythritol, xylitol, most preferably sorbitol and glycerol, cyclic polyols, preferably glucose, fructose, mannose, galactose, oligofructose, inulin, isomaltulose, trehalose, sugar substitutes, preferably mannitol, isomalt, maltitol, lactitol, and aromatic polyols, preferably cyanidin, corilagin, digallic acid, tannic acid and gallic acid, and combinations thereof.

12. The method of claim 1 , wherein the at least one polysaccharide comprises alginate, the at least one polyol comprises glycerol, and the at least one cross-linking agent comprises citric acid.

13. The method of claim 1 , wherein the at least one polysaccharide comprises alginate, the at least one polyol comprises glycerol, and the at least one cross-linking agent comprises tartaric acid.

14. 10. The method of claim 1, wherein the at least one polysaccharide comprises alginate, the at least one polyol comprises sorbitol, and the at least one cross-linking agent comprises citric acid.

15. 10. The method of claim 1, wherein the at least one polysaccharide comprises alginate, the at least one polyol comprises sorbitol, and the at least one cross-linking agent comprises calcium chloride.

16. A capsule for preparing a beverage from a beverage powder or a beverage powder mixture by introducing water, obtainable by the method according to any one of claims 1 to 15.

17. The capsule is characterized in that it comprises at least one layer of coating; said at least one layer has a swelling degree of 20% to 900%, preferably 60% to 850%, very particularly preferably 100% to 800%, and / or A capsule for preparing a beverage by introducing water, preferably a capsule according to claim 16, wherein said capsule swells on contact with water by 0.3% to 6.0%, preferably 0.5% to 5.5%, most preferably 1.0% to 4.0%.

18. 17. The capsule of claim 16, wherein the coating comprises 2 to 50 layers, preferably 2 to 20 layers, very preferably 2 to 10 layers, most preferably 2 to 5 layers.

19. 19. The capsule of claim 18, wherein the individual layers of the coating have a thickness of 30 to 600 μm, preferably 50 to 300 μm, most preferably 50 to 200 μm.

20. 17. Capsule according to claim 16, wherein the capsule absorbs a maximum force in a breaking strength test of at least 25 N, in particular at least 50 N, preferably at least 100 N, in particular after being rinsed with water.

21. 17. Use of a capsule according to claim 16 for preparing a beverage.

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