Method and system for producing coffee tablets

Abstract

A process for producing a coffee tablet comprising the steps of: i) providing a uniformly wetted mass of baked and ground coffee having a water content of from 3% to 11% by weight; ii) feeding the wetted material to a dosing device; iii) placing a dose of wetted coffee into a cavity of a molding apparatus, the cavity having a bottom surface (35a), a top surface (32a) and a peripheral surface, the bottom surface (35a), the top surface (32b) and at least a portion (22a) of the peripheral surface being configured to define a compression space (CS) for the dose of wetted coffee; iv) compressing a dose of wetted coffee (DGC) into the cavity (22) to form a coffee tablet (1); v) removing the coffee tablet (1) from the cavity (22). Step iv) comprises compressing a dose of wetted coffee (DGC) while said portion (22a) of said peripheral surface is heated at a temperature different from, preferably lower than, the temperature at which at least one of the bottom surface (35a) and the top surface (32a) is heated.

Description

Technical Field

[0001] The invention relates to the coffee industry and has developed a method particularly directed to the production of tablets or similar dosage units without a functional shell, formed starting from roasted and ground coffee powder, for beverage preparation devices. The tablets obtainable by the system and method according to the invention are designed preferably for automatic and semi-automatic preparation machines, but without excluding the tendency to use them in other preparation devices (for example, coffee machines of the "moka" or "Neapolitan" type, or cafetiere coffee machines or percolator devices). Background Art

[0002] The preparation of liquid food products starting from pre-portioned doses of precursors on preparation machines or devices is widespread, in particular for the preparation of hot beverages such as espresso.

[0003] In some known solutions, the dose of the beverage precursor has a functional shell, i.e. it is packaged in a more or less hard capsule, and the corresponding preparation machine is designed to cause the preparation liquid (generally water) to pass through this capsule to dispense the beverage. For other preparation devices, the precursor dose is contained in a flexible and water-permeable functional shell, usually a paper shell, usually called a "pod". In some cases, the pod is intended for automatic or semi-automatic preparation machines, while in other cases, the pod is intended for coffee machines or percolation coffee makers. In any case, even in these solutions, the flexible and permeable functional envelope is also passed through by the preparation liquid flow.

[0004] Packaging a single dose of the precursor in its functional housing implies various disadvantages related to higher cost of the product, greater complexity of the production process, the need for ecologically correct disposal of the used capsules or pods and environmental impact due to the associated gaseous emissions.

[0005] These problems have been solved in the past by proposing to create precursor dosage units with a self-supporting structure that does not necessarily require a functional shell, in particular in the form of tablets or pills. In this way, the pills (or tablets) can be packaged in groups in the same container (for example a bag formed of a material with good oxygen barrier properties), thus avoiding rapid deterioration of the product (usually due to oxidation phenomena). Therefore, these tablets are designed to be inserted as is into the relevant preparation machine, i.e. the beverage preparation process does not presuppose the use of a functional shell.

[0006] EP 0229920 A1 discloses a method for preparing a coffee tablet, which involves compacting a mass of roasted and ground coffee particles with a compressive force in the range of 20.7 MPa to 48.3 MPa, the coffee particles having a moisture content of at least 3% by weight and an average coffee particle size of 0.4 mm to 2.0 mm. Preferably, the moisture content of the roasted and ground coffee particles is 3% to 6% by weight, their average size is 0.6 mm to 1.2 mm, and the compressive force is 27.6 MPa to 41.4 MPa. The pressure used is such that the volume of the mass of roasted and ground coffee particles is reduced to 55% to 30% of the original volume of the wetted mass. The final density of the tablet is 0.60 to 0.95 g / cm3. The compacting operation is performed by placing a dose of coffee particles between opposing elements and pushing these elements toward each other. These opposing elements include a die base and a punch, the die base defining a tubular recess of the desired shape at one end opening, and the punch being slidably received in the recess.

[0007] In the first practical example of the above document, a single tablet having a diameter of 100 mm and a thickness of about 9.2 mm with flat end walls is obtained from 60 g of wetted coffee powder. Such a tablet can be used to prepare about 8-10 cups of coffee. In a different comparative example, different compression forces are applied to 5 different portions of 4% wetted coffee powder with an average coffee particle size of 1 mm, starting from a thickness of 23.5 mm. The results are as follows.

[0008] Table 1

[0009]

[0010] Another comparative example of this document relates to tablets having a diameter of 7.62 cm and a weight of 24 or 47 g, and tablets having a diameter of 10.2 cm and a weight of 47 g.

[0011] WO 2019 / 106413 A1 discloses another method for preparing coffee tablets, which involves grinding coffee beans to obtain the corresponding powder, then humidifying the coffee powder in a cold steam cloud, and forming a dose of moistened coffee powder by inserting it into a mold matrix. The dose is then heated and compressed to form a tablet having the desired shape, wherein the compression does not cause deformation of individual coffee particles. The humidification of the coffee powder is carried out during the loading of the dose into the mold matrix, and the powder is heated during both the loading and compression stages, raising the temperature of the mold parts to a predetermined value of 60°C to 86°C in order to determine the sintering of the coffee powder particles, thereby obtaining tablets with a compacted and stable shape. The size of the coffee particles is 200 to 1000 microns, and the PSD (particle size distribution) is 65 to 90% within 200 microns, depending on the extraction method of the beverage for which the tablet is intended. The dose of coffee powder is 6-12 grams. The cold steam is obtained from an aqueous solution of 2-10% sodium chloride and 2-10% sucrose. The cold steam supply is carried out in pulses and the supply time does not exceed two seconds.

[0012] The examples in this document provide two possible processes, the starting materials being roasted coffee with a moisture content of 3% to 6%, and green coffee with a moisture content of 9% to 12%. In both cases, the weight of the starting dose was 7 and 12 g. By compressing the dose at a pressure of 40-160 MPa, tablets with a mass of 7.2 to 11.8 g, a density of 0.95 to 1.29 g / cm3 and a residual moisture of 3-4.5% were obtained.

[0013] WO 2021 / 033011 A1 discloses another method for producing coffee tablets, in which a dose of coffee powder is moistened and fed into a mold matrix, then heated and compressed. The starting dose contains at least a first portion of powder with a particle size between 500 and 900 microns and a second portion of powder with a particle size less than 200 microns, respectively, to form tablets weighing between 6 and 12 grams, wherein the first portion is 70 to 90% by weight and the second portion is 10-30% by weight. The inner surface of the mold matrix is ​​first moistened by spraying a liquid solution on it, then 50-70% of the second portion is fed in sequence, then 100% of the first portion is fed in, and finally the remaining 50-30% of the second portion is fed, followed by compression with a punch while heating.

[0014] The surface layer of the tablet is heated by electrically heating the matrix and punches to 55-85°C or by microwaves. The effect of the process is that the larger particles of the first part will be inside the tablet, surrounded on the outside by a dense layer of the finest particles.

[0015] The known methods indicated have some drawbacks related to the failure to obtain the correct organoleptic properties in the final beverage, as well as problems with the integrity of the tablets, for example due to dusting, breakage and, above all, the formation of transverse cracks in the tablets. Summary of the invention

[0016] In summary, the present invention aims to solve the above-mentioned disadvantages by an improved method for producing coffee powder tablets. A subsidiary object of the invention is to indicate a method which can be implemented in a simple manner.

[0017] According to the invention, at least one of the above objects is achieved by a method, a system and a tablet having the features indicated in the appended claims. Said claims form an integral part of the technical teaching provided herein in connection with the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Other objects, features and advantages of the present invention will emerge from the following description made with reference to the accompanying drawings, which are provided as non-limiting examples only, in which:

[0019] - Figure 1 and 2 are schematic perspective and front views of a coffee powder tablet according to a possible embodiment;

[0020] - Figure 3 is a schematic diagram of a possible method of producing a coffee powder tablet according to a possible embodiment;

[0021] - Figure 4 is a partial schematic perspective view of an apparatus for molding coffee powder tablets, which apparatus can be used in a method according to a possible embodiment;

[0022] - Figure 5 Is in a closed or compressed state Figure 4 a schematic partial cross-sectional view of an apparatus of the type shown;

[0023] - Figure 6 yes Figure 5 A schematic cross-sectional view of a portion of an apparatus intended to identify certain components of the compression space;

[0024] - Figure 7 , 8 and 9 are based on different possible implementation schemes Figure 4 a schematic partial cross-sectional view of a punch of an apparatus of the type shown; and

[0025] - Fig.10 Photographic images of coffee tablets obtained as a result of the comparative test are shown. DETAILED DESCRIPTION

[0026] References to embodiments in this specification indicate that the specific configuration, structure or feature described in the embodiment includes at least one embodiment. Therefore, phrases such as "in one embodiment", "in various embodiments", etc., which may be present in different places in this specification, do not necessarily refer to the same embodiment. In addition, the specific configuration, structure or feature defined in this specification can be combined in one or more embodiments in any suitable manner, even different from those described. The numbers and space marks (such as "upper", "lower", "top", "bottom", etc.) used herein are only for convenience, so they do not limit the scope of protection or the scope of the embodiment. In this specification and the appended claims, the indication that the tablet or dosage unit mentioned has a self-supporting structure without a functional shell is intended to indicate that these tablets or units do not need the presence of a shell for the extraction of beverages (liquid coffee), such as capsules or flexible and permeable coatings, that is, they are designed to be inserted into the relevant preparation machine as it is: of course, it is not excluded that for the purpose of sale and storage, the tablet or dosage unit is packaged in a suitable container, such as a bag, a bag, a tray, etc.

[0027] The same reference numbers are used in the figures to indicate similar or technically equivalent elements.

[0028] Figure 1 and Figure 2 For illustrative purposes a coffee dosage unit or coffee tablet obtainable according to a possible embodiment of the invention is shown, consisting of a compacted mass of coffee powder, having a self-supporting structure and without a functional shell (i.e. without a capsule body or a shell body made of a flexible and permeable material).

[0029] In the illustrated case, the tablet 1 has a substantially cylindrical central portion 2, and two opposite end portions 3 and 4 of reduced diameter. The portions 3 and 4 each define an end face 3a, 4a of the tablet 1, are preferably flat, and preferably have a corresponding rounded peripheral portion 3b, 4b for connection to the central portion 2. As described below, this type of embodiment facilitates the removal of the tablet 1 from the associated mold during the production process.

[0030] However, other solid forms of tablets are not excluded. Preferred forms are those characterized by a geometry of revolution (including substantially annular or frustoconical forms) which allow to obtain an optimal compaction of the coffee powder in the method described below: in particular, these forms allow to maintain the equidistant peripheral surface of the tablet relative to its core or center, which is particularly advantageous in the proposed method for the reasons described below. Other possible shapes of tablets are those characterized by a curved surface (e.g. substantially spherical or ellipsoidal).

[0031] Figure 3A possible sequence of operations for a method of producing a tablet according to the invention is represented in simplified form.

[0032] A denotes a first step, consisting in obtaining a mass GC of roasted and ground coffee. A second step B then represents a stage of preferably uniform humidification of the mass GC, so as to obtain a moistened (i.e. having a predetermined water content) coffee WGC mass. A purely explanatory example shows the case of a horizontal screw mixer 10, which is arranged above a tank 11, which may be heated, so that the generated water vapor penetrates into the mixer 10 and then into the coffee powder. Humidification can also be accomplished by spraying water (or other suitable aqueous solutions) directly onto the ground coffee GC, simultaneously or subsequently with mixing, so as to obtain a mass WCG having a predetermined uniform water content. According to one aspect of the invention, the predetermined water content is approximately 3-11% by weight of the mass WGC, preferably 4-6%.

[0033] C denotes a third step, in which the moistened coffee material is fed to a dosing system 12, by means of which doses DGC of moistened coffee powder are fed, by means of at least one dosing nozzle 12a, into corresponding cavities 13a of the molding device, for example cavities at least partially defined in the lower mold part 13'. In the illustrative example, the system 12 comprises a plurality of dosing nozzles 12a to add a plurality of doses DGC in the respective cavities of the mold part 13'. However, the case of a single dosing nozzle is not excluded from the scope of the present invention, which single dosing nozzle can be used to controllably deliver a dose DGC in the lower single-cavity mold part, or to deliver several doses DGC in succession in each cavity of a multi-cavity mold part. The dosing system 12 can be manufactured according to any technique known in the industry.

[0034] Step D schematically represents the fourth step, in which each dose of moistened coffee DGC is pressed into a corresponding cavity 13a of a mould part 13', in particular by means of at least one corresponding upper mould part 13", for example having at least one punch insertable into the cavity itself and sliding therein. The actuation system 14 of the moulding device 13', 13" (for example only the upper mould part 13") can be of any known design, preferably based on the use of at least one hydraulic cylinder. In various embodiments, the compression of the dose can be discontinuous, i.e. carried out with pressure and release phases, with pressure modulation according to different types of curves (increasing pressure, decreasing pressure and / or various combinations thereof), the pressure phases having a modularity. Such a solution can be advantageous depending on the type of coffee used, its initial characteristics, the desired organoleptic properties.

[0035] It will be seen that, according to one aspect of the invention, at least two parts 13', 13" of the molding device define between them a compressed space or volume for the dose DCG, wherein the surfaces defining this space are heated in a differentiated manner. Also in this case, in a possible embodiment, the heating can be discontinuous, that is, it can be carried out with different heating stages, with temperature modulation according to different types of profiles (increasing temperature, decreasing temperature, heating pauses and / or various combinations), with modularity of the heating stages; this solution may also be advantageous depending on the type of coffee used, its starting characteristics, the desired organoleptic characteristics.

[0036] Thus, compression can be performed with simultaneous heating of at least two mold parts 13 ′ and 13 ″. In case of heating with temperature regulation including heating pauses, part of the compression can be performed without heating.

[0037] Step E illustrates the subsequent step of extracting each tablet 1 from the associated cavity of the molding device, for example from the mold part 13'. The extraction can be performed in any known manner, for example by using a system using a suction extraction element, or by providing a lower mold part 13' in which the bottom of each cavity 13a itself is defined by a lower punch that can slide upwards to lift the tablet to a position outside the cavity; alternatively, it is possible to provide a lift of a portion of the lower mold part 13', or of only a portion of the peripheral surface defining the corresponding cavity 13a, so that each tablet remains resting on a fixed punch below the bottom defining the cavity itself.

[0038] Regardless of the implementation of the mould and the extraction method, the tablet 1 can then be placed on a conveyor system 15 for the purpose of subsequent operations. In the exemplary embodiment, a marking step F is provided, during which a distinctive mark or identification code is defined in a known manner on the top surface of the tablet 1. The marking can also be carried out by corresponding recessed or embossed impressions on the various parts of the mould. The marking step F can be followed by a residual heat removal step G, for example by a suction system or ventilation device 17.

[0039] Afterwards, the tablets 1 can be packaged. The tablets 1 can be packaged individually or in groups in a suitable container with sufficient oxygen barrier properties, such as a bag, a bag, a tray, a tubular container. The tablets 1 can be vacuum packed in a suitable package.

[0040] As described above, according to the present invention, the predetermined moisture content of the coffee powder to be introduced into the tablet molding cavity is indicatively 3% to 11% by weight, preferably 4% to 6% by weight of the corresponding dose. According to another aspect of the present invention, a dose of moistened coffee required to form a tablet is compressed while the middle area of ​​the compression space has a different temperature than at least one of the lower area and the upper area of ​​the compression space. Preferably:

[0041] - the aforementioned intermediate region is defined by a corresponding portion of the peripheral surface of the molding cavity;

[0042] - the lower area is defined by the bottom surface of the moulding cavity, which bottom surface may belong to the lower punch, and

[0043] - The upper zone is defined by the surface of the upper punch which is driven to actively compress the dose of moistened coffee DGC.

[0044] In various embodiments, a molding device or apparatus for implementing the present invention comprises at least two mold parts configured to compress a dose of moistened coffee therebetween within a corresponding molding cavity, wherein the at least two mold parts define a bottom surface, a top surface, and a peripheral surface of the cavity.

[0045] For illustrative purposes only, Figure 4 A possible device for moulding coffee tablets according to the invention is shown, which device is indicated as a whole by 13 and which essentially comprises two mould parts. In this figure, 19 indicates a base on which is mounted a lower mould part 13', which is here obtained by two superimposed parts (indicated by 20 and 21), preferably formed of a heat-conducting material, for example a metallic material, for example stainless steel. Figure 5 As shown (wherein the mold 13 is shown in cross section and in a closed state), the lower part 20 defines or is associated with a series of punches 35, here the shape of the punches 35 is roughly cylindrical, each punch 35 is inserted into a corresponding through cavity 22 of the upper part 21, here the shape of the punches 35 is roughly cylindrical. In this example, the lower mold part 13' has nine molding cavities, each defined by a cavity 22 and a corresponding lower punch 35, but the number of cavities can of course be different. In this example, it is assumed that the parts 20 and 21 of the mold part 13' are fixed and the removal of the tablet 1 from the molding cavity 22 is performed by a gripper / lifting system operated by suction. Incidentally, in other embodiments, the parts 20 and 21 of the mold can be separable mold parts, allowing different types of tablets to be extracted.

[0046] Refer again Figure 4 and 5, 13″ denotes an upper mould part, which is connected to a corresponding actuation system 14 and which may also have two superimposed parts 30 and 31, although this is not an essential feature. A series of upper punches 32 protrude from the lower surface of part 31, here substantially cylindrical, the number of which corresponds to the number of cavities 22 of the lower mould part 13′. Likewise, a series of positioning and guide pins 33 protrude from the lower surface of part 31 of the mould part 13″ for insertion into corresponding positioning and guide channels 23 provided in part 21 of the lower mould part 13′.

[0047] The facing surfaces of the punches 32 and 35 realize the bottom surface and the top surface of the molding cavity, respectively, in this example. Figure 5 It is shown how the above-mentioned opposing surfaces of the punches 32 and 35 define corresponding forming surfaces or cavities 32a and 35a in various preferred embodiments so that the two end surfaces of the tablet have corresponding shapes, for example Figure 1 and 2 The shapes of the parts 3 and 4 of the tablet 1 are shown. Here, a limited part of the cylindrical surface of the cavity 22 in the mold part 13' is defined (at Figure 6 22a) is used to define the outer peripheral contour of the middle part of the tablet 1 instead.

[0048] like Figure 5 As shown, when the mold 13 is in the closed state, each cavity 22 and the corresponding lower punch 35 and upper punch 32 define a compression space or volume for a dose of moistened coffee, the compression space having:

[0049] - an intermediate area defined by a corresponding portion of the peripheral surface of the cavity 22,

[0050] - a lower area defined by the forming surface 35a of the lower punch 32, and

[0051] An upper area defined by the forming surface 32 a of the upper punch 32 .

[0052] Compressed space or volume Figure 6 22a denotes the aforementioned portion of the cylindrical surface of the cavity 22, which identifies the middle region CSi.

[0053] As described above, at least during the compression phase intended to obtain a dose of moistened coffee DGC of the tablet 1, the middle region Csi of the compression space CS has a temperature different from, and preferably lower than, at least one of the lower region CSb and the upper region CSt. In various preferred embodiments, the temperature of both the lower region CSb and the upper region CSt is higher than the temperature of the middle region Csi; however, in some cases, the middle region and the lower region may be at the same temperature. In various preferred embodiments, the upper region CSt is at a higher temperature than the lower region CSb.

[0054] In general, the tests carried out by the applicant have made it possible to determine the preferred temperatures as follows:

[0055] - Upper zone CSt: 55 to 100°C;

[0056] - Intermediate range CSI: 40 to 95°C; and

[0057] - Lower zone CSb: 50 to 95°C.

[0058] The Applicant has noticed that the controlled heating of the side surfaces 22a of the compression space CS significantly reduces the problem of the formation of lateral cracks in the tablets, which is related to the rebound phenomenon, i.e. a kind of rebound of the compressed material that occurs when the compression is released. Surprisingly, the controlled heating of the compression space sides leads to a significantly lower rebound effect, even compared to the "cold" molding of the compressed tablets for more than twice the time and also at higher pressures. Due to the reduction of the rebound effect, in various embodiments, it is possible to organize the heating and compression of the dose according to successive stages, and it is also possible to adapt the process to different types of coffee and different organoleptic properties by adjusting the parameters or modular management of the stages.

[0059] Therefore, the proposed solution of differential heating of the die can effectively solve the problem of transverse crack formation in the tablet and reduce the compaction time, thus benefiting the productivity, especially when using multi-cavity dies.

[0060] This advantageous effect is believed to be related to the fact that the use of a lower temperature in the middle zone Csi of the compression space allows limiting the evaporation of water from the middle portion 2 of the tablet 1. On the other hand, the use of a higher temperature in the upper zone CSt, compared to the middle zone Csi and the lower zone CSb, has the effect of compensating for the shorter contact time between the upper punch 32 and the coffee dose DGC.

[0061] In any case, heating of the entire coffee mass is obtained according to a controlled temperature gradient between the surface area and the central area of ​​the tablet, which allows reaching in this central area the temperatures necessary for the agglomeration processes (in particular associated with so-called agglomeration), indicatively between 40°C and 60°C, in particular about 50°C.

[0062] Thermographic analysis of the tablets during the molding phase confirmed the efficient distribution of the temperature, according to a curve with a zone-dependent gradient, where the central zone of the tablet is advantageously kept at a lower temperature, preserving its organoleptic properties.

[0063] In various embodiments, the differential heating in different areas or surfaces of the space CS is obtained by providing suitable heating means in different parts of the mold. In various embodiments, one mold part is equipped with means for heating the top surface of the molding cavity, while the other mold part is equipped with means for heating the bottom surface of the molding cavity and at least a part of its peripheral surface.

[0064] exist Figure 4 and 5 In the case shown, the movable mold part 13" is equipped with resistors 31a for heating the punches 32, in particular their lower surface 32a. In this example, the resistors 31a can be arranged in the part 31 of the mold part 13", from which the punches 32 protrude, and the resistors 31a extend along the length, the resistors 31a being located at positions corresponding to a corresponding row of punches 32 (three punches 32 in the example case). In this type of embodiment, heat transfer occurs by conduction between the essentially plate-shaped part 31 and the punches 32; for this purpose, the part 31 and the punches 32 are preferably made of a heat-conducting material, preferably a metal material, such as stainless steel.

[0065] In various embodiments, a substantially similar heating arrangement is also provided for heating the lower punches 35, thus having a plurality of resistors 20a arranged in the portion 20 of the mold part 13', each resistor 20a extending along the length at a corresponding row of punches 35 (three punches 35 in the example case). In this case as well, the heating of the punches 35, in particular of their upper surfaces 35a, and the heat transfer are carried out by conduction between the substantially plate-shaped portion 20 and the punches 35; as with the mold part 13", the portion 20 and the punches 35 are preferably made of a heat-conducting material, preferably a metallic material, such as stainless steel.

[0066] Similar heating resistors can be used to heat the cavity 22 of the portion 21 of the mold part 13', in particular the corresponding portion of the surface 22a defining the compression space Cs. In the example case, the portion 21, preferably also made of a heat-conducting metal material such as stainless steel, has two sets of resistors 21a and 21b, also extending longitudinally.

[0067] In various embodiments, resistors 21a and 21b are arranged crosswise at different heights within portion 21 (see, for example, Figure 5). With such an arrangement, the resistors 21a and 21b thus form a kind of grid structure, each cavity 22 being heated by a corresponding portion of at least two different crossed resistors 21a and 21b. In a non-limiting example, two resistors 21a and two resistors 21b are provided, so that the extended portion of the cavity closest to the peripheral contour of the portion 21 is subjected to a slightly lower conduction heating than the portion closest to the resistors. In principle, there is no obstacle to providing four resistors 21a and four resistors 21b, so that even in the above-mentioned portion of the cavity closest to the peripheral contour of the portion 21, there is extended a corresponding portion of the resistor 21a or 21b: however, the Applicant has found that, in practice, and with reference to the exemplary case of a nine-cavity mold 22, the use of only four resistors 21a and 21a does not significantly affect the quality of the molding and, above all, simplifies the realization of the portion 21, allowing its weight and overall dimensions to be reduced. The various portions 20, 21 and 31 equipped with resistors are equipped with suitable temperature sensors, for example in the form of thermocouples, for detecting and controlling the temperature of the surfaces 22a, 31a and 35a according to the process requirements. The operation of the resistors is managed by a control system not shown, preferably according to signals obtained by temperature sensor means. The use of resistors is advantageous in terms of temperature control, but in a possible variant embodiment they can be replaced by conduits in which a suitable heating fluid, such as water, flows.

[0068] In other embodiments, the heating resistors may be arranged vertically and extend in the region between four adjacent cavities. Another possibility is to provide a heating resistor inside each punch 35, such as a vertically arranged heating resistor (although this involves a greater vertical obstruction of the corresponding mold part).

[0069] In general, the temperatures chosen for the different zones of the compression space CS, as well as the corresponding initial moisture values ​​of the coffee powder (in any case between 3% and 11% by weight) and the diameter of the tablet (preferably varying between 3.5 and 5.5 cm), depend on variables such as:

[0070] a) Type and roast color of coffee;

[0071] b) the particle size of the coffee powder;

[0072] c) x50 / powder ratio;

[0073] d) the amount of coffee powder in a single dose;

[0074] e) tablet thickness;

[0075] f) compression time of a certain dose of coffee powder;

[0076] g) force and compression curve applied to a dose of coffee powder;

[0077] h) the residual moisture value required for tablets;

[0078] i) the desired density of the tablet;

[0079] l) expected quality loss;

[0080] The variables that led to satisfactory results in the tests conducted by the applicant are as follows.

[0081] a) Coffee type and roast color: Arabica, Robusta, Arabica / Robusta blends, roasted between 25 and 65°N.

[0082] b) Granulometry: 200 to 700 μm, preferably 270 to 450 μm for espresso and 350 to 550 μm for filter coffee.

[0083] c) x50 / powder ratio: 15 to 25 μm for espresso and 20 to 35 μm for filter coffee.

[0084] d) Mass: 4 to 20 g, preferably 4-11 g for espresso and 6-20 g for filter coffee.

[0085] e) Thickness: 5mm to 25mm, preferably 5-20 for espresso, 8-25 for filter coffee.

[0086] f) Compression time: up to 180 seconds.

[0087] g) Compression force and profile: Up to 17 kN per cavity, preferably 7 to 8.5 kN.

[0088] h) Residual moisture value: 2 to 5%.

[0089] i) Desired density: 0.4 to 0.9 g / cm3, preferably 0.5 to 0.6 g / cm3 3 .

[0090] l) Expected quality loss: less than 5%.

[0091] As about Figure 1 and 2 Said, in a preferred embodiment, the tablet 1 obtained by the process according to the invention does not have a precise cylindrical shape, but rather has a shape characterized by a substantially cylindrical central portion 2 and two shaped end portions 3 and 4, wherein the portions 3 and 4 each define:

[0092] - the end faces 3a, 4a of the tablet 1 are preferably flat and have a smaller diameter than the central part 2, and

[0093] - rounded peripheral portions 3b, 4b for connection to the central portion 2.

[0094] In this perspective, Figure 7 , 8 9 and 9 represent possible cavities 32a of punch 32, preferably corresponding to the cavity of the bottom of the moulding cavity (this bottom is represented in the given example by punch 35, which has a corresponding cavity 35a). The outlines shown allow obtaining Figure 1 and 2 In tablet shapes of the type shown, surfaces I and II are intended to define the end faces (3a, 4a) and the connecting faces (3b, 4b) of the tablet, respectively.

[0095] Figure 7 A cavity in which the radius of surface II is substantially equal to or close to 90° is particularly advantageous for eliminating breakage during tablet removal from the die and mass loss of the same tablet. However, this shape implies that, in order to lift the tablets (especially from the lower punch), a twist is applied to them: this complicates the process and generates dust during removal from the die.

[0096] refer to Figure 8 and 9 , cavities in which the radius of surface II is gentler (closer to 45°, in any case between 30° and 60°) allow easier removal of the tablets without twisting (and therefore without dust) and do not substantially determine the formation of lateral cracks.

[0097] The applicant has Figure 7-9 The profile mentioned in the test was compared with a compression profile that was essentially completely cylindrical. The test conditions were as follows:

[0098] - Starting coffee powder with a moisture content of 5.3% to 5.7%

[0099] -Ratio x50 / powder = 324 μm / 18.79%

[0100] -Surface temperature 32a, 22a, 35a: 85 / 85 / 80℃

[0101] -Compacting time: 30s.

[0102] With Figure 7-9 Compared to the shapes obtained with the profile of , the cylindrical shape showed much higher mass loss in the tablets (1.07% vs. 0.56%, 0.66% vs. 0.71%) and, most importantly, transverse cracks were formed with an incidence greater than 50%. Fig.10 Photographic images representing the results of comparative tests are shown; in this figure, part A) relates to completely cylindrical tablets, while parts B), C) and D) relate to tablets obtained from Figure 7 , 8 and a tablet with an end profile of 9.

[0103] From the description given, the characteristics and advantages of the invention are clear. The proposed solution makes it possible to quickly and easily produce tablets for extracting beverages starting from roasted and ground coffee powder, wherein the problems of forming transverse cracks in the tablets are eliminated or in any case greatly reduced.

[0104] It will be obvious to a person skilled in the art that many modifications are possible without departing from the scope of the invention as defined in the accompanying claims.

[0105] It should be noted that, for example, one or more parts of the method (e.g. Figure 2 One or more of stages CF) can be carried out in a nitrogen atmosphere.

[0106] In possible variant embodiments, the portion of the coffee mass designed to make tablets may include a smaller portion of soluble coffee, which may be uniformly mixed with the roast and ground coffee, or confined to the central area of ​​the tablet, or layered within the tablet.

[0107] The actual implementation of the molding device may be different from that illustrated in the figure, but it does not affect the provision of heating devices or elements designed to heat at least a portion of the peripheral surface of the molding cavity in a differential manner relative to at least one of the bottom surface and the top surface of the same cavity. For example, the mold may include at least three parts, such as:

[0108] - an intermediate part having a through hole to define a peripheral surface of the moulding cavity and provided with heating means designed to heat at least a portion of this peripheral surface (in particular the portion thereof which laterally defines the compression space or volume of the coffee powder dose)

[0109] - a lower part defining a lower punch, the proximal end of which defines a bottom surface of the compression space or volume and provided with heating means designed to heat said bottom surface, and

[0110] - an upper part defining an upper punch, the proximal end of which defines a top surface of the compression space or volume and provided with heating means designed to heat said top surface.

[0111] In this type of embodiment, the middle part of the mold may be fixed, while the lower and upper mold parts may be movable to compress a dose of coffee.

[0112] Another possibility is to provide a two-part mould, each part defining a respective end surface (top or bottom surface) and a respective portion of the peripheral surface of the compression space or volume. In this case, each mould part will be equipped with means designed to heat its end surface and the respective portion of the peripheral surface. In this type of embodiment, one or both mould parts may be movable to compress the dose of coffee therebetween.

Claims

1. A method for producing a coffee tablet or similar coffee dosage unit having a self-supporting structure without a functional shell, comprising the following steps: i) providing a wetted mass of roast and ground coffee (WGC) having a moisture content of 3% to 11%, preferably 4% to 6%; ii) feeding the moistened material (WGC) to a dosing device (12) to obtain a dose of moistened coffee (DGC); iii) placing a dose of moistened coffee (DGC) into a cavity (22) of a molding device (13), the cavity (22) having a bottom surface (35a), a top surface (32a) and a peripheral surface, the bottom surface (35a), the top surface (32b) and at least a portion (22a) of the peripheral surface being configured to define a compression space (CS) for the dose of moistened coffee (DCG); iv) compressing a dose of wetted coffee (DGC) into the cavity (22) to form a coffee tablet (1); v) removing the coffee tablet (1) from the cavity (22); Wherein step iv) comprises compressing a dose of moistened coffee (DGC) while said portion (22a) of said peripheral surface is heated at a temperature different from, preferably lower than, the temperature at which at least one of the bottom surface (35a) and the top surface (32a) is heated.

2. The method according to claim 1, wherein the temperature of the bottom surface (35a) and the top surface (32a) are both higher than the temperature of the portion (22a) of the peripheral surface.

3. The method according to claim 2, wherein the top surface (32a) has a higher temperature than the bottom surface (35a).

4. The method according to any one of claims 1 to 3, wherein: - the temperature of the top surface (32a) is 55 to 100°C; - the temperature of said portion (22a) of the peripheral surface is between 40 and 95°C; and - The temperature of the bottom surface (35a) is 50 to 95°C.

5. Method according to any one of claims 1 to 4, wherein the particle size of the roast and ground coffee is 200 to 700 μm, preferably 270 to 450 μm for espresso, or 350 to 550 μm for filter coffee.

6. The method according to any one of claims 1 to 5, wherein the coffee tablet (1): - if used for preparing espresso, has a thickness of 5 to 20 mm; - if used for the preparation of filtered coffee, has a thickness of 8 to 25 mm; The diameter of the tablet (1) is preferably 3.5 to 5.5 cm.

7. The method according to any one of claims 1 to 6, wherein the weight of the dose of moistened coffee (DCG) is: -4 to 11 g, if the coffee tablet (1) is used for preparing espresso, -6 to 20 g, if the coffee tablet (1) is used for preparing filter coffee.

8. The method according to any one of claims 1 to 7, wherein the dose of moistened coffee (DCG) is compressed for a time not exceeding 180 seconds.

9. The method according to any one of claims 1 to 8, wherein the dose of moistened coffee (DCG) is compressed with a compression force not exceeding 17 kN, preferably between 7 and 8.5 kN.

10. The method according to any one of claims 1 to 9, wherein step iv) comprises - providing a die part (13″) having at least one punch (32), the punch surface defining one of said top surface (32a) and said bottom surface (35a), - inserting a punch (32) into a portion of a cavity (22) defined by another mould part (13') such that the punch surface (32a) causes compression of a dose of moistened coffee (DGC), - Remove the punch (32) from the cavity (22).

11. A coffee tablet or similar coffee dosage unit having a self-supporting structure without a functional shell, obtainable by a method according to any one of claims 1 to 10, the tablet (1) being based on roasted and ground coffee powder with a particle size of 200 to 700 μm, wherein the tablet has: -Weight from 4 to 20 grams; - 3.5 to 5.5 cm in diameter; -Thickness from 5mm to 25mm; -2 to 5% residual moisture content; -0.4 to 0.9 g / cm 3 density.

12. Tablet according to claim 11, having a body having at least partially a substantially cylindrical shape or having a substantially rotational geometry.

13. A tablet according to claim 12, wherein the body of the tablet (1) has a substantially cylindrical central portion (2) and two opposite end portions (3, 4), each of which defines an end face (3a, 4a) and a rounded peripheral surface (3b, 4b) connected to the central portion (2).

14. A system for producing coffee tablets or similar coffee dosage units having a self-supporting structure without a functional shell, the system comprising a feeding device (10-11), a dosing device (12) and a molding device (13), wherein the feeding device (10-11) is designed to feed a moistened mass of roasted and ground coffee (GC) to the dosing device (12), wherein the dosing device (12) is designed to place a dose of moistened roasted and ground coffee (DGC) into a corresponding cavity (22) of the molding device (13), wherein the molding device (13) comprises at least two mold parts (13', 13"), the at least two mold parts (13', 13") being designed to compress a dose of moistened roasted and ground coffee (DGC) into the cavity (22), the at least two mold parts (13', 13") defining a bottom surface (32a), a top surface (35a) and a peripheral surface of the cavity (22); wherein a compression space (CS) of a dose of moistened roasted and ground coffee (DGC) is defined between said bottom surface (35a), said top surface (32a) and a corresponding portion (22a) of said peripheral surface, And wherein the molding device (13) includes a heating device (20a, 21a, 21b, 31a), which is controllable and is used to heat the portion (22a) of the peripheral surface in a differential manner relative to at least one of the bottom surface (35a) and the top surface (32a).

15. System according to claim 14, wherein said at least two mould parts (13'; 13") are controllable to compress a dose of moist roasted and ground coffee (DGC) while heating said portion (22a) of the peripheral surface at a temperature different from, preferably lower than, the temperature at which at least one of said bottom surface (35a) and said top surface (32a) is heated.

16. A system according to claim 14 or 15, wherein the portion (22a) of the peripheral surface, the bottom surface (35a) and the top surface (32a) are formed so that the tablet (1) has a shape that is at least partially substantially cylindrical or has a substantially rotational geometry.

17. A system according to claim 16, wherein the portion (22a) of the peripheral surface, the bottom surface (35a) and the top surface (32a) are formed so that the tablet (1) has a shape of a central portion (2) and two opposite end portions (3, 4), the central portion (2) being substantially cylindrical, each end portion (3, 4) defining an end face (3a, 4a) and a rounded peripheral surface (3b, 4b) connected to the central portion.

18. System according to any one of claims 14 to 17, wherein the heating means (20a, 21a, 21b, 31a) comprises an electrical resistor.

19. System according to any one of claims 14 to 18, wherein the molding device (13) comprises at least: - a first mould part (13') defining at least said portion (22a) of the peripheral surface of the cavity (22); a second mould part (13″) having at least one punch (32) insertable into the cavity (22) of the first mould part (13′), the punch (32) having a respective punch surface (32a) defining one of the top surface (32a) and the bottom surface (35a), At least a second mould part (13") is movable relative to the first mould part (13') for compressing a dose of wet roast and ground coffee (DGC) into the cavity (22) by means of at least one punch (32).

20. System according to any one of claims 14 to 19, comprising extraction means configured for removing the coffee tablet (1) from the cavity (22) of the moulding means (13).

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