Systems and methods for preparing coffee tablets and the like

Abstract

A method is described for producing tablets for the extraction of liquid foods, each tablet being formed starting from at least one ingredient in granular or powder form, and in order to form each tablet, a dosed and moistened amount of said ingredient is irradiated with microwaves while contained within a limited volume. The method comprises: a) providing said raw material in powder or granular form; b) loading at least one dosed amount of said ingredient into each formed cavity; and c) irradiating the at least one dosed, moistened amount of the ingredient while it is contained in the respective forming cavity. Step b) comprises loading a plurality of dosed amounts of the ingredient into respective forming cavities of a multi-cavity forming device, and step c) comprises introducing the multi-cavity forming device into a multi-mode cavity of a microwave oven and then removing the multi-cavity forming device from such cavity. The multi-mode cavity is pre-configured in such a way that the microwave irradiation causes heating of all of the dosed amounts of the ingredient in each forming cavity of the multi-cavity forming device to simultaneously form a plurality of tablets, each having a free-standing structure.

Description

[Technical Field]

[0001] The present invention relates generally to the preparation of liquid foods and has been developed with particular attention to the production of tablets for the extraction of liquid foods, starting from at least one ingredient in granular or powder form, in particular coffee powder. The tablets obtained by the system and method according to the invention are designed for preferred use in automatic and semi-automatic preparation machines, although their design for use in other preparation devices, such as "moka" or "napoli" type coffee makers, or press filter coffee makers or percolator devices, is not excluded. [Background technology]

[0002] The preparation of liquid foods using preparation machines or devices, starting from pre-portioned doses of precursors, is widely used, in particular for the preparation of hot beverages such as espresso coffee.

[0003] In some prior art solutions, doses of beverage precursor are packaged in capsules of greater or lesser rigidity, and the corresponding preparation machines are in each case designed to allow the preparation liquid (typically water) to pass through such capsules and to dispense the resulting beverage.

[0004] In other preparation devices, the precursor doses are instead contained in a flexible, water-permeable casing, typically made of paper, commonly called a "pod." The pod may be intended for use in automatic or semi-automatic preparation machines, or alternatively in coffee makers or percolators. In these solutions, too, the pod passes through the flow of preparation liquid in either case.

[0005] Packaging single precursor doses entails various drawbacks in terms of higher product costs, a significantly more complex manufacturing process, and the need for correct and environmentally responsible disposal of the final capsules or pods.

[0006] Such problems have been addressed in the past by proposing the production of precursor dose tablets with a self-supporting structure that does not necessarily require an outer casing. Such pills or tablets may be packaged in groups in one and the same container, for example a bag made from a material with good oxygen barrier properties, to avoid rapid deterioration of the product (typically due to oxidation phenomena).

[0007] For example, WO2014 / 064623A2 and WO2020 / 003099A1 disclose systems and methods for producing tablets for the extraction of hot beverages, such as coffee or similar products, starting from corresponding powder precursors, based on the use of microwaves.

[0008] The method described in WO2014 / 064623A2 essentially comprises: - a wetting system for adding a given amount of water to the powder precursor; - a homogenizing device for mixing the powder precursors and providing a substantially uniformly wetted mixture; - a dosing unit for dispensing a predetermined dose of the moistened mixture; - a forming device having a hollow body suitable for receiving a dose of the moistened mixture; - a compression device associated with the hollow body for actively compressing the dose of moistened mixture and forming a tablet of the desired shape; a microwave generator connected to an associated antenna for directing a microwave beam of fixed frequency into the hollow body while the mixture dose is being actively compressed, thus causing overheating and / or sintering of the precursor, thereby obtaining a tablet having a relatively dense, self-supporting structure that does not require an outer coating; The present invention provides the use of a configuration comprising:

[0009] Such prior art solutions therefore allow the production of tablets that can be used in common preparation machines and devices, which do not necessarily have to be individually packaged in corresponding casings, but are instead suitable to be packaged in groups, for example in a single bag.

[0010] However, the productivity of the methods and configurations proposed in the cited prior art documents is limited, considering that the tablets have to be formed and processed individually, i.e., one at a time. Also, as shown subsequently in WO 2020 / 003099 A1, the steps for wetting and homogenizing the powder precursor provided in WO 2014 / 064623 A2 have to be carried out manually, using particularly complex means, resulting in an increase in the time for producing each tablet.

[0011] In order to overcome these and other drawbacks, WO2020 / 003099A1 describes all the operating units necessary for producing tablets by microwaves, thus: - a tank for supplying the precursor as granules or leaves, - a device for grinding precursors, - a device for wetting the ground precursor material; - a device for mixing and homogenizing the ground and moistened precursors, - a dosing device for obtaining a single dose of the milled and moistened precursor material; - a forming device associated with the pressure device for receiving a dose of the crushed and moistened precursor material and forming therefrom a tablet of a predetermined volume; - an irradiation device for irradiating the dose of ground and moistened precursor with microwaves while it is kept in a compacted state in the forming device in order to superheat the particles of the dose and bring about partial roasting and / or sintering; The present invention proposes an automatic device that essentially integrates the above.

[0012] To enable the production of tablets with different characteristics, the aforementioned operating units and therefore the corresponding process parameters (milling, wetting, homogenization, weighing, forming, and irradiation) can be controlled differently by a single control system.

[0013] The aforementioned forming device disclosed by WO 2020 / 003099 A1 comprises a substantially carousel-type displacement support which holds a plurality of cavities, each cavity intended to receive a respective dose of ground and moistened precursor material. Thus, by activating the displacement device, each cavity can be individually displaced from a loading position, in which the cavity receives a dose of moistened precursor material, to a processing position, in which the cavity is inside a suitable irradiation chamber, in which a microwave generation device is operating. In the processing position, the cavities are axially aligned under pressure devices which are activated to keep the doses contained in the cavities in a state of active compression during the irradiation phase. After heating, and therefore after the active pressure is turned off, the cavities can be moved to an ejection position, where the tablets are ejected from the corresponding cavities.

[0014] The apparatus disclosed by WO2020 / 003099A1 can be designed to include multiple grinding, wetting, dosing, forming, and irradiation devices to increase productivity. In this respect, the proposed apparatus is also advantageous over the prior solution according to WO2014 / 064623A2 in terms of process time and number of tablets obtained per unit time.

[0015] However, the solution according to WO2020 / 003099A1 also suggests that each tablet be individually formed and treated with microwaves, sometimes placed in an irradiation chamber designed to contain a single cavity and compress its contents, thus strongly limiting the production capacity of the device. Summary of the Invention

[0016] Broadly speaking, the present invention aims to overcome the aforementioned drawbacks and in particular to provide a method and system for producing tablets of the indicated type more efficiently from a production and energy point of view. A secondary aim of the invention is to make it possible to obtain high quality tablets while providing them with a relatively smaller amount of energy than the cited prior art solutions.

[0017] According to the present invention, at least one of the above objects is achieved by a system, a method and a tablet having the features set out in the appended claims.

[0018] The claims are an integral part of the technical teachings provided herein regarding the present invention. [Brief explanation of the drawings]

[0019] Further objects, features and advantages of the present invention will become more apparent from the following description, made with reference to the accompanying drawings, given purely by way of non-limiting example, in which: [Figure 1] 1 is a schematic perspective view showing a tablet for the extraction of liquid food according to a possible embodiment; FIG. [Figure 2] 1 is a schematic cross-sectional view of a tablet for the extraction of liquid foods according to a possible embodiment. [Figure 3] 1 is a schematic perspective, partially exploded view of a mold usable in methods and systems according to possible embodiments; [Figure 4] 1 is a detailed diagram of a mold that can be used in methods and systems according to possible embodiments. [Figure 5] 1 is a schematic diagram intended to illustrate a possible sequence of steps (and operating units) of a process (and system) for manufacturing tablets for the extraction of liquid foods, according to a possible embodiment. [Figure 6] 1 is a schematic diagram intended to illustrate a possible sequence of steps (and operating units) of a process (and system) for manufacturing tablets for the extraction of liquid foods, according to a possible embodiment. [Figure 7] 1 is a schematic cross-sectional view intended to illustrate possible modes for propagating microwaves in a multimode cavity of an oven for irradiating a forming device usable in methods and systems according to possible embodiments. FIG. [Figure 8] FIG. 10 is a diagram intended to illustrate the dynamics for reducing the weight of a tablet after treatment with microwaves. DETAILED DESCRIPTION OF THE INVENTION

[0020] Reference to an "embodiment" herein indicates that a particular configuration, structure, or feature described with respect to that embodiment is included in at least one embodiment. Thus, phrases such as "in an embodiment," "in various embodiments," and the like, which may appear in various places throughout this specification, do not necessarily refer to one and the same embodiment. Furthermore, particular shapes, structures, or features defined herein may be combined in any suitable manner in one or more embodiments, even in ways different from those shown. Numerical and spatial references (e.g., "upper," "lower," "top," "bottom," etc.) used herein are merely for convenience and therefore do not define the scope of protection or the range of embodiments. In the figures, the same reference symbols are used to indicate similar or technically equivalent elements.

[0021] In the following description and the appended claims, unless expressly stated otherwise, terms such as "feedstock" or "precursor" shall be understood to refer interchangeably to a single substance or a mixture of several substances.

[0022] 1, reference number 1 indicates as a whole a tablet for the extraction of a liquid food product according to a possible embodiment, formed starting from a powdered or granular precursor or raw material, in particular a precursor or raw material that is substantially insoluble in water; in the following, it should be assumed that the precursor is ground and roasted coffee powder, for example obtained from Arabica beans or a mixture obtained from Arabica and Robusta beans. The invention is also applicable to other types of precursors (for example barley, malt, tea, ginseng, decoctions, broths or soup preparations) that are in each case amenable to being transformed into powder or granules by processes known per se and that, when combined with water, produce a liquid food product.

[0023] Broadly speaking, the tablet 1 has a solid body with two end faces 2, 3, and a peripheral surface 4. In the example shown, the tablet 1 is essentially disc-shaped and therefore has a substantially cylindrical peripheral surface. Of course, other shapes are possible.

[0024] The tablets may have a diameter comprised between approximately 20 and 60 mm (for example, about 40 mm) and a thickness comprised between 5 and 50 mm (for example, 12 and 13 mm for espresso coffee and 25 and 30 mm for "double" / "lungo" coffee or filter coffee). Their weight may be comprised between 3 and 30 g (for example, 8 and 10 g for espresso coffee and 12 and 15 g for "double" / "lungo" coffee or filter coffee).

[0025] 2, in various embodiments, the body of tablet 1 has a self-supporting structure distinguished by the presence of a crust or outer shell 5 and an inner core 6, both of which are formed from the same precursor material, in this case coffee powder, but have different compactnesses. In particular, outer shell 5, which preferably defines both end faces 2, 3 and peripheral surface 4, has a compact, substantially rigid structure and acts as a "container" for inner core 6, which has a less compact structure. In particular, even in core 6, the precursor material can remain in a substantially loose, powdery or granular state. As will become apparent below, such a distinct structure of tablet 1 can be obtained by a specific treatment process that allows, among other things, to reduce the alteration of the organoleptic properties of the precursor material dose forming tablet 1.

[0026] In the manufacturing method according to the invention, each tablet 1 is formed starting from a dosed and moistened amount of the respective precursor, which is irradiated with microwaves while contained in a limited volume.

[0027] According to the present invention, multiple dosed amounts of precursor material are loaded into respective cavities of a multi-cavity forming device, which is then introduced into a multimode cavity of a microwave oven. The multimode cavity of the oven is pre-configured in such a way that all dosed amounts of raw material inside each forming cavity of the forming device are heated simultaneously by microwave distribution within the cavity itself, after which the multi-cavity forming device is removed from the multimode cavity of the microwave oven. This allows multiple tablets 1 to be formed simultaneously and quickly. As will become clear below, the proposed method also makes it possible to obtain advantages in terms of energy savings.

[0028] In a particularly advantageous embodiment, the multimode cavity of the microwave oven is configured substantially as a tunnel, the multicavity forming device being displaced according to the forward direction between the inlet and the outlet of the multimode cavity. Such a solution may allow a further increase in productivity and allow a substantially continuous processing suitable for producing a large number of products in a time unit.

[0029] In a preferred embodiment of the present invention, a step is provided for selectively wetting each dosed amount of raw material, i.e., only its surface layer, before introducing the forming device into the multimode cavity of the microwave oven. Such a wetting step is carried out in particular after each dosed amount of raw material has been loaded into each forming cavity of the forming device. This local wetting of each dose of precursor makes it possible to obtain the structure described above with reference to FIG. 2, which ensures advantages, for example, in terms of energy saving, reduces processing times and reduces dusting phenomena, as will be explained hereinafter.

[0030] In a preferred embodiment, microwaves are irradiated in the multimode cavity of the oven starting from several microwave sources, or in any case microwaves are introduced into the multimode cavity from several different zones. Such a solution makes it possible to improve the distribution of energy in the multimode cavity and thus to obtain a uniform heating of the doses of several precursors contained in the forming cavities of the forming device.

[0031] In a preferred embodiment, during irradiation in the multimode cavity of the oven, a dosed amount of precursor material is contained in each forming cavity of the forming device without active compression. As will be appreciated, such a solution allows for a considerable simplification of the forming device for its processing in the multimode cavity of the oven. In any case, it may be preferable to subject the dosed amount of raw material contained in the forming cavity to active compression, at least temporarily, before introducing the forming device into the oven. This active compression may be useful for determining the initial compaction of the dose in the forming cavity concerned or for determining its initial size and density.

[0032] In various embodiments, the method for manufacturing tablets according to the present invention is implemented by a system configured as a substantially continuous production line comprising a series of subsystems or operating stations through which one or more portions of the forming device pass according to an advancement direction.

[0033] Broadly speaking, the above system: - at least one forming subsystem configured (i.e. having means) for imparting a predefined shape to the tablet; - at least one loading subsystem configured (i.e. having means) for supplying a dosed amount of precursor material to each forming cavity of the forming subsystem; - at least one wetting subsystem configured (i.e. having means) for wetting at least a portion of each precursor dose; - at least one heating subsystem configured (i.e. having means) for applying microwaves to the raw material while it is housed in the respective forming cavity of the forming subsystem; - at least one conveying subsystem configured to (i.e., having means for) displacing the forming subsystem through at least the heating subsystem; Equipped with.

[0034] The forming subsystem includes the multi-cavity forming device described above, and the loading subsystem is designed to load multiple dosed amounts of raw material into each forming cavity of the forming device. The heating subsystem includes the microwave oven described above including a corresponding multi-mode cavity into which the forming device is introduced and removed by the delivery subsystem in such a manner that the microwaves heat all of the dosed amounts of raw material within each forming cavity.

[0035] As can be seen in a preferred embodiment of the manufacturing system according to the present invention, the transport subsystem comprises: - one or more first units or stations for handling parts of the forming device upstream of the microwave oven; - a loading unit or station upstream of the microwave oven for loading multiple dosed amounts of raw material; - a pressing unit or station upstream of the microwave oven for pressing a plurality of dosed amounts of raw material; - a wetting unit or station upstream of the microwave oven for partially wetting a plurality of dosed quantities of raw material; - one or more second units or stations downstream of the microwave oven for handling parts of the forming device; - a separation unit or station downstream of the microwave oven for removing tablets from the forming device or from parts thereof; - a unit or station downstream of the microwave oven for dehydrating and / or drying and / or cooling the tablets; and - Units or stations for packaging tablets are also configured (i.e. provided with means) to displace at least one portion of the forming device in an advancing direction between a series of other operating units or stations selected from

[0036] FIG. 3 shows diagrammatically a possible multi-cavity forming device, substantially of the type generally designated 10, that can be used in accordance with the present invention.

[0037] In various embodiments, the forming device 10 comprises a main portion 11 having a plurality of forming cavities 11a partially defined therein, and at least one second portion 12 releasably connectable to the main portion 11 to close the cavities 11a at at least one of its axial ends. In the illustrated case, a plurality of through holes 11a' extend between two larger faces of the main portion 11, here substantially parallelepiped-shaped, forming peripheral surfaces of the cavities 11a, preferably having a substantially circular cross section. The device 10 further comprises both a bottom portion 121 and a head portion 122 intended to overlap the larger faces of the main portion 11 to close corresponding cavities 11a at two opposite ends. In other embodiments not shown, the bodies 11 and 121 may be replaced by a single body, and the holes 11a' configured as blind holes will therefore have a lower height than illustrated. In the schematic example, the device 10 is configured to define 40 forming cavities 11a, although of course this number may be more or less.

[0038] In various embodiments, such as the one illustrated in Fig. 3, the bottom part 121 and the head part 122 are substantially plate-like and each have a number of protrusions 12a intended to be at least partially inserted into the hole 11a' like a plug. To this end, the protrusions 12a preferably have a cross-sectional shape with a slightly reduced diameter that substantially corresponds to the shape of the hole 11a'. The connection between the protrusions 12a and the hole 11a', or more generally, the connection between the one part 121 and 122 and the other part 11, need not necessarily be of the sealing type, for reasons that will be explained below (and without prejudice to the fact that the parts 11, 12 can in each case provide suitable passages for the evacuation of steam from the cavity 11a).

[0039] Providing protrusion 12a is preferred, but does not represent an essential feature, taking into account that one or both faces of parts 121 and 122 intended to be connected to the corresponding faces of part 11 may be flat, in which case hole 11a' has a lower height than that illustrated in Figure 3.

[0040] 3, the sum of the heights of the protrusions 12a is less than the height of the holes 11a', thus defining in the cavity 11a a volume suitable for accommodating a dose of each precursor in the assembled state of the device 10. Such confined volume is bounded laterally by an intermediate cylindrical strip of the peripheral surface of the holes 11a' and, at the bottom and top, by the end faces of the protrusions 12a in portions 121 and 122, respectively.

[0041] In various preferred embodiments, the forming device or one or more of its parts has at least one fluid circuit configured (i.e., has means) for supplying a wetting fluid to each forming cavity, and to this end, each forming cavity preferably has a respective wetting passageway fluidically connected to the aforementioned hydraulic circuit, such passageway being in at least one surface bounding the respective cavity.

[0042] In the illustrated case, the end faces of the projections 12a of the parts 121 and 122 intended to be inserted into the holes 11a' have defined therein passages 12b suitable for introducing a wetting fluid into the cavity 11a. In this way, the fluid can be introduced into the two axial ends of each cavity 11a.

[0043] The passages 12b are connected to respective ducts belonging to the aforementioned hydraulic circuit, which is represented only diagrammatically and generally designated 13, and which are provided with respective inlets 13a defined herein on the peripheral side of the corresponding portions 121 and / or 122. In the schematic example, the various arrays of passages 12b are connected in parallel to the respective branches of the hydraulic circuit 13, but other circuit solutions making it possible to supply fluid by any technique known per se are naturally possible.

[0044] In various embodiments, similar wetting passages are additionally or alternatively provided in at least a portion of the peripheral surface of cavity 11a. For example, referring to FIG. 4, an array of passages 11b is defined in the cylindrical surface of bore 11a' in corresponding annular bands intended to laterally delimit a volume suitable for accommodating a dose of precursor. To this end, said bands may be defined by a cylindrical wall provided with passages 11b, which are surrounded by respective chambers 13b supplied by corresponding hydraulic circuits 13. In this case too, other circuit solutions for supplying wetting fluid to the several passages defined in the peripheral wall of cavity 11a are of course possible.

[0045] Naturally, in a possible variant, the fluid system of the forming device can be designed or controlled to determine local wetting of only one or both axial end regions of the dosed amount of precursor, or only its peripheral region, and in such cases the final tablet therefore does not have a complete shell of the type shown above, but has one or more crusts with similar characteristics only in the pre-selectively wetted areas (for example, crust 5 only on surface 2 and / or surface 3, or crust 5 only on peripheral surface 4, and other combinations are possible).

[0046] At least a portion of the device 10 that defines the forming cavity 11a is made from a microwave transparent material, preferably a polymer, such as a thermoplastic material.

[0047] For example, a material that can be used for this purpose is polyetheretherketone (PEEK), an organic thermoplastic polymer with excellent mechanical properties (strength, hardness, low density), excellent thermal properties (ability to withstand high temperatures and resistance to thermal fatigue), excellent chemical strength, and high abrasion resistance with low friction. This material, optionally filled (e.g., with glass fibers), is ideally suited for handling food. In both cases, the materials used may also be provided with a suitable coating (e.g., with PTFE) to prevent material release.

[0048] The parts 11 and 12 of the forming device may be manufactured by any known technique, such as additive techniques or 3D printing, that allows the production of structures of the illustrated type in a relatively simple manner. Such techniques are also advantageous for the purpose of defining the hydraulic circuits inside parts 11, 12, which are suitable to be made from several parts obtained by additive techniques and then assembled together in a sealed manner, if necessary, after positioning possible control elements (such as valves or flow dividers) between them.

[0049] The wetting passages 11b and / or 12b, and the corresponding hydraulic circuits, may optionally be in the form of micropassages and microducts, respectively. As mentioned, the hydraulic circuits of one or more of the parts 11, 12 may be provided with suitable electrically operated control devices, such as valves, possibly of miniaturized type (for example obtainable using MEMS: Micro Electro Mechanical Systems) technology.

[0050] Preferably, the parts 11, 12 of the device 10 are held in their assembled position by suitable releasable connecting elements. In the case illustrated in Figure 3, for example, bottom portion 121 and head portion 122 have lateral engagement members, indicated at 15a and 15b, intended to be releasably connected to main portion 11. Naturally, additionally or alternatively, interconnecting members may be provided between portions 121 and 122, i.e. intended to connect to each other and not to portion 11. The connecting elements used may be of any known design, for example designed for a snap connection, but a release mechanism may in any case be provided that can be activated, for example by pressing, to allow the disconnection thereof and thus subsequent separation of portions 11 and 12.

[0051] 5 and 6 show schematic diagrams of a possible system for the production of tablets according to the invention, configured as a processing line with several subsystems or operating stations. In describing such figures, reference will be made to various elements of device 10 not shown in these figures (e.g., cavity 11a, hole 11a', protrusion 12a, passages 11b-12b, members 15a-15b, circuit 13), which should be referred to in this regard in FIG. 3.

[0052] In various preferred embodiments, the system comprises a transport subsystem configured (i.e. having means) for obtaining a displacement of the forming device 10 or parts 11, 121, 122 thereof between the various operating stations according to a forward direction indicated by X. Preferably, the transport system comprises a plurality of conveyor devices 20 arranged in succession. In the following, for the sake of brevity, the case will be described in which a conveyor device 20 is provided for each operating station, but this should not be considered an essential feature, considering that one and the same conveyor 20 can serve at least two consecutive operating stations.

[0053] In a preferred embodiment, the conveyor device 20 is a belt conveyor. Preferably, the belt 21 is made at least partially from a microwave-transparent material, for example a polymeric or synthetic material, optionally provided with a coating suitable for preventing material release. Usable materials are, for example, PEEK or PP or PTFE or Kevlar or glass fiber, optionally with a coating made from PTFE or others, and more generally any material commonly used for food industry purposes. In any case, metal belts of the type currently used in the food industry, for example made from stainless steel, cannot be excluded from the scope of the present invention (although their use may lead to a certain degree of complexity in the design of the oven irradiation system).

[0054] 5, a starting operating station is indicated with A, in which the bottom parts 121 of the forming devices are loaded with their respective protrusions 12a facing upwards onto the transport subsystem, in particular onto the belt 21 of the corresponding conveyor device 201. The bottom parts 121 may be placed onto the belt 21 by techniques known per se, for example automatically by an operating device, after having been subjected to a corresponding cleaning and / or drying cycle, for example using air or another gas.

[0055] The part 121 therefore advances to the station designated B on the corresponding conveyor 202, where an automatic device 30 positions the main part 11 of the forming device on the corresponding bottom part 121, with the protrusion 12a of the bottom part 121 being inserted into the lower end of the hole 11a' of the part 11. At this stage, the two parts 11 and 121 are also mechanically coupled to each other, for example, using the member 15a of FIG. 3, which is snap-engaged with the part 11. The device 30 may, for example, be a manipulator apt to translate the part 11 vertically. The positioning can be managed by a controller supervising the operation of the processing line or station B, based on detection performed using a sensor system or detector of a design known per se. In this case, the part 11 may also be subjected to a cleaning and / or drying cycle before being placed on the belt 21. Of course, the functions described with reference to stations A and B may be performed in a single station, or the pre-connected parts 11 and 121 may be loaded directly, even manually, onto a subsequent station indicated at C.

[0056] The combined parts 11 and 121 therefore proceed on a corresponding conveyor 203 to a station designated C, which is configured to feed a dosed amount of precursor into the corresponding forming cavity, i.e., through the upper end of the hole 11a' of part 11. Station C may, for example, comprise a tank 40 to which the pre-obtained precursor, in powder or granular form, is directly fed. Station or subsystem C may optionally comprise a suitable grinding system upstream of tank 40, generally designated 40a.

[0057] The precursor may have an initial moisture content comprised between 5% and 20% by weight, preferably between 8% and 12%. To this end, if necessary, a system for initial wetting of the precursor and a corresponding mixing system may be provided upstream of the tank 40 (and downstream of a possible grinding system).

[0058] In various preferred embodiments, the loading station C is configured to simultaneously supply multiple dosed amounts of precursor to multiple formation cavities 11a. To this end, in the case illustrated in the figures, multiple nozzles or outlets 41, preferably shaped and sized to be at least slightly insertable into the holes 11a' from their upper ends, are associated with the tank 40, particularly in a number corresponding to the number of cavities 11a. To this end, the tank 40 and / or the nozzles 41 are preferably controllably translatable at least vertically. Preferably, the nozzles 41 include or have associated upstream a suitable dosing system using known techniques (volumetric, weighing, time) for dosing the amount of precursor to be introduced into each formation cavity 11a.

[0059] After the precursor loading step, the parts 11 and 121 advance on the corresponding conveyor 204 to a subsequent station D, which is configured to subject the plurality of dosed amounts of precursor contained in the respective forming cavities 11 a to temporary active compression. The pressing station D may comprise a single, e.g. pneumatically operated, pressing device 50 apt to vertically translate a plurality of pressing elements 51, in particular a number corresponding to the number of cavities 11 a. The pressing elements 51 preferably have a shape and size such that they can be inserted with minimal clearance into the holes 11 a′ of the part 11 in order to precisely press the dosed amounts of precursor contained therein.

[0060] At the end of the active compression stage, parts 11 and 121 advance on corresponding conveyors 205 to a subsequent station E, where an automated device 60 (e.g., similar to device 30 at station B) positions head portion 122 of the forming device on main portion 11, with protrusion 12a of head portion 122 inserted into the upper end of hole 11a' in main portion 11. At this stage, part 122 is mechanically coupled to part 11, for example, using member 15b of FIG. 3 , which snaps onto part 11, completing forming device 10. After part 122 has been positioned on part 11, forming cavity 11a is now closed. In this case, too, positioning may be managed by a controller of the processing line or of station E, based on detection performed using a sensor system of detectors of known design.

[0061] As mentioned above, the sum of the heights of the protrusions 12a of portions 121 and 122 is less than the height of the holes 11a' of portion 11, thereby defining a volume within cavity 11a suitable for accommodating each dosed amount of precursor in the assembled state of device 10. In various embodiments, such volume is in each case greater in height than the overall dimensions of the pressed dose accommodated in the corresponding cavity 11a. In other words, after pressing in step / station D, the height of the pressed dose of precursor may be less than the height of the corresponding forming cavity, understood as the distance between the end faces of protrusions 12a of portions 121 and 122. In this way, a uniform minimum free space (suggestively greater than 1 mm) may be present within the cavity above each dose to allow for slight expansion of the volume during subsequent heating. In other embodiments, the height of the protrusions 12a of portions 121 and 122 may further be selected so that in the assembled state of device 10, the enclosed volume substantially corresponds to the dosed amount or so that the protrusions 12a maintain the dosed amount in at least a slightly compressed state.

[0062] The forming device 10 then advances on a corresponding conveyor 206 to a subsequent station F, which is configured to provide partial or localized wetting of a plurality of dosed amounts of precursor contained in the corresponding cavities 11 a. The wetting station includes a fluid system 70 designed to supply a wetting fluid to the cavities 11 a with the aid of a hydraulic system integrated in the forming device 10, in particular the circuit 13 of FIGS. 3 and / or 4. To this end, in various embodiments, the fluid system 70 comprises one or more movable hydraulic ducts or connections 71, each designed to automatically connect and disconnect to a respective inlet 13 a of the aforementioned hydraulic system of the device 10.

[0063] The system 70 and the hydraulic circuit are designed to allow a substantially predetermined amount of wetting fluid to flow through the passages 12b and 11b (FIGS. 3-4) into the forming cavity. Such supply of fluid, e.g., pure water, is preferably carried out mechanically, i.e., using a pump or similar device suitable for forcing the liquid into the cavity. Additionally or alternatively, the possibility of superficially wetting the dosed amount of precursor in a substantially passive manner, e.g., by utilizing capillary or absorption phenomena, is not excluded from the scope of the present invention. The injected wetting fluid may be water vapor instead of water. According to other embodiments not shown, wetting may be achieved by condensing vapor on a cold wall (e.g., on the cold precursor dose or on a cold wall in contact with the precursor dose of the tablet to transfer moisture).

[0064] Considering that, as explained above, it is not strictly necessary to uniformly wet the dosed amount of precursor, the amount of fluid added is reduced in any case. As mentioned, the amount of fluid supplied is preferably such that it wets only one surface layer of each dosed amount of precursor, preferably at its edge and peripheral surfaces, or possibly even at only one of such surfaces. Naturally, part of the fluid will tend to spread towards the center of the dose as well, but also considering that the time between the local wetting step and the subsequent heating step is relatively short (approximately less than 50 seconds), this diffusion must be considered negligible.

[0065] In various embodiments, at least one of the steps preceding the heating step is carried out in an atmosphere with a low oxygen content or in an atmosphere amended with an inert gas (such as nitrogen or argon); this may be done, for example, for the loading step (Station C), the possible pressing step (Station D), the step for closing the formed cavity (Station E), and the wetting step (Station F).

[0066] After the wetting step, the forming device 10 then proceeds to a heating station G on a corresponding conveyor 207 . Such a station comprises a microwave oven, indicated at 80, having a multimode cavity 81 in which the devices 10 are held for a processing time sufficient to obtain tablets 1. As mentioned above, in a preferred embodiment, the microwave oven 80 is a tunnel-like oven, with each multimode cavity 81 extending longitudinally between an inlet IN and an outlet OUT, through which the forming devices 10 pass in the forward direction X. Preferably, the length dimension of the cavity 81 is such that the devices 10 are temporarily accommodated entirely within the cavity as they pass between the inlets IN and OUT.

[0067] In various preferred embodiments, the oven 80 is equipped with a plurality of means 82 for generating microwaves, for example with a suitable system 83 known per se, in order to transmit the microwaves into a multimode cavity 81 associated therewith. Preferably, a plurality of microwave sources 82 of any type suitable for the application (for example known magnetrons) are provided with associated waveguides 83 configured to introduce microwave beams MW from their multiple zones into the multimode cavity 81. Optionally, suitable mirrors or similar elements 85 may also be provided in the multimode cavity for guiding the reflection of the microwaves MW in the desired direction, all according to techniques known per se. A substantial advantage of multimode microwave processing is the possibility of simultaneously heating a large number of precursor doses.

[0068] 5 shows diagrammatically the case of an oven 80 provided with two microwave generators 82 and corresponding waveguides 83 arranged to obtain irradiation from above and from below in a multimode cavity 81, which should of course be understood as merely an example, taking into account that in practical implementations of the invention the multimode cavity and the microwave generation and distribution system may provide a different number of generators and different configurations of irradiation / reflection points. The waveguides 83 could also be replaced by suitable antennas connected to the corresponding generators by coaxial cables.

[0069] In general, the multimode cavity 81 and the systems 82, 83, 85 for generating and distributing microwaves MW are optimized by known techniques depending on the dimensions of the load represented by the precursor dose contained in the forming device 10, and in this regard it should be noted that the use of microwave ovens, also of tunnel shape, having multimode cavities is now widely used in various fields, including the food manufacturing industry.

[0070] It should therefore be emphasized that the distribution of microwaves MW in the multimode cavity 81 as shown for station G in Fig. 5 is provided for the purpose of schematic representation only. Fig. 7 also shows, in schematic form, a cross-section of a possible multimode cavity 81 that can be used to implement the invention, in this example utilizing the hexagonal section of the cavity 81 to reflect the microwave beams MW coming from the four waveguides 83 towards the forming device 10 and thus towards the precursor doses contained therein in order to obtain uniform heating of the doses. (As mentioned above, the conveyor belt 21 is preferably made from a material that is transparent to microwaves; the same applies to the material forming the part of the device 10 that defines the forming cavity 11a.)

[0071] As mentioned above, the cavity 11a defined between the portions 11-12 of the forming device is not hermetically sealed, thereby allowing for the evacuation of vapors that may be generated during microwave heating of the locally moistened precursor dose. Of course, the portions 11-12 can also be designed to define suitable vapor evacuation passages.

[0072] The multimode cavity 81 may be provided with a vapor extraction system including, for example, one or more extraction fans.

[0073] The simultaneous continuous production of tablets, and in particular their processing in oven 80, is simplified due to the separation of the step for active compression of the precursor doses (performed at station D) from the step of irradiation by microwaves (performed at station G).

[0074] As mentioned, the method for producing the oven and its cavity varies depending on the load to be heated, and its optimization can be obtained using techniques known per se, in particular from similar applications in the food industry. This applies in particular to the resonant frequency of cavity 81, i.e. the frequency of the signal output by source 82, and the characteristics of the corresponding systems 83, 85 for transmitting and possibly reflecting microwaves (for example, as is known, the sizing of the waveguide determines modal propagation and distribution phenomena). Generally, source 82 is preferably configured to generate an alternating electromagnetic field with a radiation frequency of oscillation up to 3 GHz, preferably between 2.40 and 2.50 GHz, most preferably close to 2.45 GHz, or below 1 GHz, preferably between 865 and 965 MHz, most preferably close to 915 MHz.

[0075] The overall power of the oven 80 depends on the number of sources used and thus on the size of the load (i.e., the number of doses to be heated simultaneously). Typically, the oven 80 may be equipped with more than two, in particular between 2 and 6, sources 82 (e.g., magnetrons) each having a power between 1 and 3 kilowatts, each source 82 preferably feeding a respective waveguide 83. More preferably, the waveguide system is configured such that the microwaves transmitted to the multimode cavity 81 irradiate the forming device 10 from both above and below, and possibly also laterally.

[0076] The moisture content has a significant influence on the dielectric properties of the charge and therefore on its heating. In the present case, after heating by microwaves, the moistened surface layer of the precursor dose hardens after heating to obtain a tablet or its shell 5.

[0077] As noted above, according to a preferred feature of the invention, the wetting step is carried out individually for each precursor dose, and is carried out in such a way as to determine a humidity gradient within the dose, such that the wetting is greater or more concentrated in at least one peripheral zone of the dose. This selective wetting results in a better bonding of the precursor particles in such zones, in particular to obtain the layer or shell 5 of the tablet, and therefore the tablet has a tougher and more resistant outer surface, which also reduces the dusting phenomenon.

[0078] The firmness of the tablet or its layer 5 is achieved mainly due to the caking phenomenon that occurs during heating in a microwave oven. Caking refers to the tendency of powder or granular materials to form clumps due to an increase in interparticle forces. The aggregation between particles without forming solid bridges can occur due to van der Waals forces, which define the intermolecular attraction. Even if the molecule is not polar, electronic substitution can make it polar for a very short time. The negative end of a molecule induces an instantaneous dipole in the surrounding molecule, which in turn attracts the positive end of the surrounding molecule (this process is essentially due to the London force, also known as instantaneous dipole-induced dipole interaction).

[0079] Consequently, it can be hypothesized that the caking of precursors, especially coffee, that occurs during microwave heating is mainly due to van der Waals forces and polar interactions, all of which increase as the interparticle distance decreases, and for this reason an active compression stage (station / stage D) carried out before microwave treatment can be useful.

[0080] In addition, stickiness phenomena may be present in some cases. For example, coffee does not contain low molecular weight sugars that typically induce stickiness and caking. However, coffee contains polymeric substances (proteins, starches, pectins) that are assumed to have similar behavior, and the presence of moisture provided in the coffee powder can lower the transition temperature of such substances (acting as plasticizers), thereby enhancing the caking of the precursors to form the shell 5 during the microwave heating step.

[0081] During the heating stage, the precursor material of each dose tends to expand, but such expansion is restricted to the limited volume of cavity 11a (as mentioned above, the useful volume of cavity 11a may be slightly larger than the volume of the dose pre-compressed at station / stage D): this slight increase in controlled volume advantageously contributes to reducing stresses in the structure of the forming tablet, reducing the risk of fracture of its matrix.

[0082] The processing time of the oven 80 is very short relative to the number of tablets to be processed, which of course depends on the load and the oven power. By way of example, in a multimode cavity 81 designed to process 40 precursor doses at a time, the processing time (or transit time in the example shown) of a forming device 10 of the illustrated type may be less than 50 seconds and may be comprised between 12 and 18 seconds, depending in particular on the applied power.

[0083] 6, after heating, the forming device 10 proceeds on the corresponding conveyor 208 to station H. This station is substantially similar to the device 60 of station E, but is equipped with an operating device 60' designed for the reverse operation, i.e. for lifting or in any case for removing the head portion 122 of the forming device 10. For this purpose, the operating device 60' has associated therewith a release system 61 configured (i.e. having means) for releasing the member 15b so as to allow the separation of the head portion 122 from the main portion 11. After removal, the portion 122 may be subjected to a stage of automatic cleaning and / or drying (e.g. by air), in particular of its protrusion 12a, and / or of its draining from the hydraulic circuit 13.

[0084] The remaining parts 11 and 121 of the forming device then move on corresponding conveyors 209 to station I. Such station is also equipped with a handling device 30' that is similar to the device 30 of station B, but is designed to be suitable for the reverse operation, i.e. for lifting or removing the main part 11 of the forming device from the base part 121. For this purpose, the handling device 30' also has associated therewith a corresponding release system 31 that is configured (i.e. has means) for releasing the member 15a to allow separation of the part 11 from the part 121. In this case too, after removal, the part 11 may be subjected to a stage of automatic cleaning and / or drying, in particular of its through-hole 11a', and / or of draining from its hydraulic circuit 13.

[0085] In various preferred embodiments, station I may include a first separation element 32, for example associated with device 30', configured to obtain the ejection of already formed tablets 1 from holes 11a' of part 11. This separation element 32 may, for example, include a system designed to introduce respective air streams from above into holes 11a', with sufficient pressure to obtain the sliding of tablets 1 into holes 11a', until the tablets emerge from the corresponding lower end and rest on protrusions 12a of base part 121. The step of blowing air (or another suitable gas) into holes 11a may advantageously be synchronized with the step of lifting part 11. The use of air streams may also be advantageous for the purpose of determining the first temperature drop of tablets 1 after microwave treatment. Instead of a pneumatic system, separation element 32 may be provided with, for example, pneumatically driven mechanical pushers for each corresponding hole 11a'.

[0086] The base portion 121 carrying the tablet 1 then passes through the corresponding conveyor 20 10 1 and moves to a station J configured to remove the tablets 1 from such portion 121. The separation station J may be made by any technique known in particular in the food industry. For example, the station J may comprise a pick-up and displacement device 90 having a vertically translatable portion, associated with a plurality of gripping members 91, e.g. pneumatically driven suction cups, the number of which corresponds to the number of tablets 1 and which are suitable for lifting the tablets 1 from the base portion 121. In a preferred embodiment, the pick-up members 91 consist of known suction cups based on Bernoulli's principle, which are suitable for contactless handling of delicate objects.

[0087] The device 90, or at least the part of it which carries the gripping member 91, is connected to a conveyor 20 of a subsequent station K which is configured for further processing of the tablets, for example for dewatering and / or drying and / or cooling thereof. 11Additionally, it may also be translatable horizontally to move the tablet 1. In various embodiments, this post-processing is carried out in an atmosphere with a low oxygen content or an atmosphere amended with an inert gas (such as nitrogen or argon).

[0088] It should be noted that upon exiting oven 80, tablet 1 has a relatively high surface temperature (e.g., comprised between 50° and 85°), which takes several minutes to dissipate. In this regard, it should also be noted that most of the moisture present in the precursor dose is not removed during the processing step in oven 80, but is removed thereafter; in particular, in the absence of dehydration, drying, or mechanical cooling, it has been observed that most moisture loss (measured by weight loss) occurs within 5 to 10 minutes after microwave treatment. The chart in FIG. 8 illustrates this aspect for tablets processed in oven 80 to heat outer shell 5 to approximately 75°C. As can be seen, for a tablet with a mass of 8.3 g exiting oven 80, substantial weight stabilization (approximately 8.15 g) is achieved after approximately 7 minutes, with a more rapid weight loss during the first 3 minutes. This weight loss (i.e., moisture content loss) is caused by the tablet still being relatively hot.

[0089] Considering that it is preferable to expose the tablets to less air after production (so as not to trigger oxidation phenomena) and therefore to shorten the time it takes for them to leave the oven 80 before being packaged, it is preferable to provide a station K which may include, for example, a dehydration or cooling tunnel 100 of a type known per se for use in the food industry.

[0090] The final moisture content, ie at the end of the tablet manufacturing process and before its packaging, is preferably less than 5% by weight.

[0091] Downstream of station K, the tablets, at substantially ambient temperature, reach station 110, where they are automatically packaged in groups in corresponding protective containers, for example bags made of a material with good oxygen barrier properties. The packaging technique employed may be of any known type, for example the vacuum type, or the MAP (Modified Atmosphere Packaging) type, or the protective atmosphere type, in which the air in the tablet container is replaced by an inert gas (for example nitrogen or argon) suitable for extending the shelf life.

[0092] As mentioned above, according to a preferred feature of the invention, the dosed amount of precursor is subjected to a partial or local wetting step, ie relative to its surrounding layer.

[0093] - Water is a lossy dielectric that has the property of absorbing electromagnetic waves and converting them into heat; - The higher the water content of the dose, the higher the dielectric constant; Considering that the higher the dielectric constant, the greater the heating effect, the water content (or moisture content) of the precursor has a considerable influence on the microwave effect, for example in the case of using microwaves or radio frequency waves.

[0094] Therefore, based on the above, increasing the moisture content of each dosed amount increases the ability of the electromagnetic waves to impart energy to the corresponding precursor, and due to this increased ability, the heating time at full power of the oven 80 can be reduced.

[0095] Practical tests carried out by the Applicant have been able to verify that the described process can be obtained, for example, by providing a dosed amount of coffee with a moisture content comprised between 7% and 14% by weight (to obtain tablets with a diameter of about 40 mm, a thickness of about 12 mm and a weight of about 8.3 g when they leave the oven) and irradiating them with microwaves to a temperature of the final surface of the tablet comprised between 70°C and 75°C.

[0096] As explained, most of the moisture content is preferably located in the peripheral layers of the dose, where the maximum energy supply obtained by the microwaves occurs, thus causing the formation of the outer crust or shell 5 of the tablet in Figure 2.

[0097] The supply of heat to the central part of the dose (i.e. the part intended to form the core 6 in FIG. 2) is instead limited and varies depending on its moisture content. When the precursor material is fed into the cavity 11a, it has a homogeneous initial moisture content, which may vary depending on the type of hardness desired for the tablet core 6. For example, in the absence of pre-wetting, the initial moisture content of the dose volume can be assumed to be, on average, 2-2.5% by weight relative to the entire dose. Such an initial moisture content makes it possible to obtain very limited heating of the central portion of the dose in the corresponding forming cavity, thereby substantially preventing its caking (in other words, the associated tablet core remains substantially powdery). On the other hand, by subjecting the precursor material to a homogeneous pre-wetting (for example, upstream of the tank 40 at station C in FIG. 5 ) to a moisture content of up to about 4.5% by weight relative to the entire dose loaded into the associated forming cavity, it is possible to obtain a higher temperature heating of the central portion of the dose, resulting in its partial caking, but this caking is significantly less than that obtained in a layer 5 that is significantly more moistened (due to the specific steps performed at station F in FIG. 5 ). Similarly, in the case of homogeneously wetting the precursor material beforehand to a moisture content of up to about 8% by weight of the total dose to be loaded into the corresponding forming cavity, it is possible to obtain a higher temperature heating of the central part of the dose, resulting in more pronounced caking thereof, but in any case still much less than the caking obtained in layer 5, for the same reasons as explained above.

[0098] As mentioned, the formation of the shell or crust 5 makes it possible to obtain a kind of container for the less dense core 6. This denser outer part of the tablet 1 makes it possible to limit the dusting phenomenon. On the other hand, supplying lower temperature heat to the central part 6 of the tablet 1 makes it possible to reduce the risk of altering the organoleptic properties of the precursor (and therefore of impairing the flavor) and to accelerate the subsequent dehydration or drying or cooling stages. For the same reason, the overall energy of the heating process can also be reduced compared to the case of uniform heating of the entire dose, considering that it is possible to concentrate the heating mainly only on the peripheral layers of the dose.

[0099] However, as mentioned, in variant embodiments, it is also possible to obtain a crust 5 on only one of the surfaces 2, 3 and 4 of the tablet 1 in order to make such a surface, for example only the upper surface 2, more robust, with the aim of engraving a possible unique mark. In these cases, the precursor must of course first be homogeneously and thoroughly wetted to ensure that the remaining part of the tablet also meets the required robustness and self-supporting characteristics after the subsequent microwave treatment.

[0100] The description outlined above clearly shows the features and advantages of the present invention. The proposed solution allows for the easy and rapid production of large quantities of tablets for the extraction of beverages, starting from a powdered or granular precursor, in particular coffee. The described system and method allow a considerable increase in productivity with respect to the prior art and are efficient in terms of energy consumption. It will be clear to those skilled in the art that numerous variations are possible without departing from the scope of the invention, which is defined by the following claims.

[0101] The system described with reference to FIGS. 5-6, configured as a continuous production line, may, of course, have a configuration different from that illustrated, without impairing its basic functionality. For example, it should be recognized that the various steps described above with respect to different operating stations can be performed at one and the same station, especially when the automated devices performing these steps are movably mounted. In this regard, for example, the steps described for stations C, D, and E can be performed at the same station, i.e., on the same conveyor 20, using devices 40, 50, and 60, respectively, and these portions can be moved to and successively superimposed on portions 121 and 11 of the forming device. The same applies to the steps described for stations I, J, and K, for example, with devices 30'-31, and 90. For example, the function of station J can be integrated into station I, placing tablet 1 directly on the conveyor that serves station K.

[0102] Instead of being configured like a tunnel, a microwave oven may have a multimode cavity with openings that serve as entrances and exits for the introduction and removal of the forming device. In such cases, the oven may be located, for example, next to the transport subsystem and may include a handling or movement component configured to introduce the forming device 10 into the multimode cavity through the aforementioned opening and then remove it therefrom. Such a component may be configured to remove the forming device from a conveyor for introduction into the multimode cavity, remove it therefrom, and then move it back to the conveyor, or may be configured (i.e., have means) to remove the forming device from a first conveyor (e.g., belonging to an upstream station of the oven), introduce it into the multimode cavity, remove it from such cavity, and then move it onto a second conveyor (e.g., belonging to a downstream station of the oven). The handling or movement component may advantageously have a movable support for the forming device, including a vertical wall (e.g., in the shape of a drawer) that tends to close a single opening of the multimode cavity when the forming device is inside the cavity.

[0103] As noted above, the same conveyor 20 can serve several successive stations. The described system or line can, of course, also include further subsystems or processing stations as deemed necessary. The following items may be included in the claims. [Item 1] A tablet for the extraction of liquid foods, having a body formed from at least one substantially insoluble ingredient in granular or powder form, wherein the body of the tablet has a self-supporting structure including an outer shell and an inner core having different densities, both formed from the at least one ingredient, the outer shell having a denser, harder structure and the inner core having a less dense structure. [Item 2] 2. The tablet according to item 1, wherein the inner core has a substantially granular or powder-like structure.

Claims

1. 1. A method for producing tablets for the extraction of liquid coffee, each tablet being formed starting from at least one ingredient in granular or powder form, said at least one ingredient being roast and ground coffee, and in order to form each tablet, a dosed and moistened amount of said at least one ingredient is irradiated with microwaves while contained within a limited volume, said method comprising: a) providing said at least one ingredient in powder or granular form; b) loading at least one dosed amount of said at least one ingredient into each formed cavity; c) irradiating said at least one dosed amount of said at least one ingredient by microwaves while contained in said respective forming cavity; Equipped with step b) comprising loading a plurality of dosed amounts of the at least one ingredient into respective forming cavities of a multi-cavity forming device; a multi-mode cavity pre-configured to heat all of the dosed amounts of the at least one ingredient in each forming cavity of the multi-cavity forming device to simultaneously form a plurality of tablets, each having a freestanding structure; and a method for manufacturing a multi-cavity forming device, the method comprising: (a) introducing the multi-cavity forming device into a multi-mode cavity of a microwave oven; (b) pre-configuring the multi-mode cavity so that irradiation of the microwaves in the multi-mode cavity causes heating of all of the dosed amounts of the at least one ingredient in each forming cavity of the multi-cavity forming device to simultaneously form a plurality of tablets, each having a freestanding structure; and (c) removing the multi-cavity forming device from the multi-mode cavity of the microwave oven.

2. 2. The method of claim 1, wherein prior to step c), a step of selective wetting of each dosed amount of said at least one ingredient is provided only in its surface layer.

3. 3. The method of claim 2, wherein the selective wetting step is performed after each dosed amount of the ingredient is loaded into the respective formed cavity.

4. 10. The method of claim 1, wherein step c) comprises irradiating the microwaves in the multimode cavity from multiple microwave sources.

5. 5. The method of claim 1, wherein step c) comprises causing reflection of at least a portion of the microwaves within the multimode cavity towards the multi-cavity forming device.

6. 5. The method according to claim 1, wherein during step c), the dosed amount of the at least one ingredient is contained in the respective forming cavity in the absence of active compression.

7. 5. The method according to claim 1, further comprising subjecting the dosed amount of the at least one ingredient contained in each forming cavity to temporary active compression, the active compression being interrupted before step c).

8. 5. The method according to claim 1, wherein during step c), the multi-cavity forming device is displaced in a forward direction between an entrance and an exit of the multimode cavity, and the microwave oven is a tunnel microwave oven.

9. 1. A system for producing tablets for the extraction of liquid coffee starting from at least one ingredient in granular or powder form, said at least one ingredient being roast and ground coffee, said system being designed to irradiate with microwaves a dosed and moistened amount of said at least one ingredient contained in a limited volume, said system comprising at least: a forming subsystem configured to impart a predefined shape to said tablet; a loading subsystem configured to supply said at least one raw material in a dosed amount into each forming cavity of said forming subsystem; a wetting subsystem configured to wet at least a portion of said at least one ingredient; a heating subsystem configured to irradiate the at least one ingredient with microwaves while it is contained in the respective forming cavity of the forming subsystem; - Transport subsystem; Equipped with the forming subsystem includes a multi-cavity forming device, and the transport subsystem is configured to cause displacement of the multi-cavity forming device; the loading subsystem is configured to load a plurality of dosed amounts of the at least one ingredient into each forming cavity of the multi-cavity forming device; and the heating subsystem has a microwave oven including a multi-mode cavity, into which the multi-cavity forming device is introduced and removed by the transport subsystem, and the multi-mode cavity is pre-configured in such a way that all dosed amounts of the at least one ingredient in each forming cavity of the multi-cavity forming device are heated by microwaves in the multi-mode cavity.

10. 10. The system of claim 9, wherein the wetting subsystem and the forming subsystem are preconfigured to obtain wetting of the at least one ingredient within the respective forming cavity of the multi-cavity forming device.

11. The system of claim 10 , wherein the wetting subsystem and the forming subsystem are preconfigured to obtain wetting of only a surface layer of a respective dosed amount.

12. 10. The system of claim 9, wherein the microwave oven includes multiple microwave sources and / or waveguides configured to supply microwave beams into the multimode cavity from multiple zones thereof.

13. 10. The system of claim 9, wherein the multimode cavity is provided with a reflective guiding element for reflecting at least a portion of the microwaves towards the multi-cavity forming device.

14. 14. The system of claim 9, wherein the multi-cavity forming device includes a first portion having at least a portion of the forming cavity defined therein, and at least one second portion releasably connectable to the first portion to close the forming cavity at at least one axial end thereof.

15. 14. The system of claim 9, wherein the multi-cavity forming device has at least one fluid circuit for conveying a wetting fluid into each forming cavity.

16. 16. The system of claim 15, wherein each forming cavity has a wetting passage in fluid communication with the fluid circuit, the wetting passage being in a surface bounding each forming cavity.

17. The system of claim 15 , wherein the wetting subsystem has one or more connecting ducts releasably connectable to respective inlets of the at least one fluid circuit of the multi-cavity forming device.

18. a first handling subsystem upstream of the microwave oven configured to couple a first portion and at least one second portion of the multi-cavity forming device to one another; and a second handling subsystem downstream of the microwave oven configured to decouple a first portion and at least one second portion of the multi-cavity forming device; The system of claim 9 , further comprising at least one of:

19. 14. The system of claim 9, wherein the loading subsystem is configured to simultaneously supply the multiple dosed amounts of the at least one ingredient into multiple forming cavities of the multi-cavity forming device.

20. - subjecting the plurality of dosed amounts of the at least one ingredient contained in the respective forming cavities of the multi-cavity forming device to temporary active compression; and - interrupting said active compression before introducing said multi-cavity forming device into said multimode cavity of said microwave oven; 14. The system of claim 9, further comprising at least one pressing subsystem upstream of the microwave oven configured to:

21. 14. The system of claim 9, further comprising at least one separation subsystem downstream of the microwave oven configured to remove the tablets from the multi-cavity forming device.

22. 14. The system of claim 9, further comprising at least one of a drying subsystem, a dehydration subsystem, and a cooling subsystem for the tablets downstream of the microwave oven and upstream of the packaging subsystem.

23. 14. The system of any one of claims 9 to 13, wherein the transport subsystem comprises at least one conveyor belt made at least in part of a microwave transparent material.

24. 14. The system of any one of claims 9 to 13, wherein the transport subsystem comprises a plurality of conveyor belts arranged in series.

25. the transport subsystem: one or more first handling stations upstream of said microwave oven for handling at least one part of said multi-cavity forming device; a loading station upstream of said microwave oven for loading said plurality of dosed amounts of said at least one ingredient; a pressing station upstream of said microwave oven for pressing said plurality of dosed amounts of said at least one ingredient; a wetting station upstream of said microwave oven for partially wetting said plurality of dosed quantities of said at least one ingredient; a heating station comprising said microwave oven; one or more second handling stations downstream of said microwave oven for handling parts of said multi-cavity forming device; a separation station downstream of said microwave oven for removing said tablets from at least one part of said multi-cavity forming device; - at least one of a drying station, a dehydration station and a cooling station for the tablets downstream of the microwave oven; - a packaging station for packaging said tablets; 16. The system of claim 11, configured to effect forward displacement of at least one portion of the multi-cavity forming device between a series of operating stations selected from:

26. 26. The system of claim 25, wherein the transport subsystem is configured to effect displacement of the multi-cavity forming device in the forward direction through an entrance and an exit of the multimode cavity of the microwave oven.

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