FR2879175A1 - Ground coffee stick pack for automatic coffee drink preparation and dispensing machine, has predetermined quantity of ground coffee in form of aggregate of ground coffee grains and having circular shape or spherical ball shape - Google Patents

Abstract

The pack has a predetermined quantity of ground coffee (12) in the form of an aggregate of ground coffee grains. The ground coffee has a circular shape or an approximately spherical ball shape. The predetermined quantity of ground coffee is introduced in a fusion chamber of a coffee drink e.g. espresso coffee, preparation and dispensing machine and compressed by a compression piston (9) of the dispensing machine. Independent claims are also included for the following: (A) a method for preparing a coffee stick pack (B) utilization of a coffee stick pack for the preparation of a coffee drink.

Description

GROUND COFFEE DOSet AND PROCESS FOR PREPARING THE SAME

  The present invention relates to a pod for the production of coffee-based beverages by infusion of ground coffee, including espresso type beverages, and a method of making such a pod.

  Preferred fields of application of the present invention will be those of the production of ground coffees and their packaging, as well as the preparation of coffee-based beverages from specific quantities of ground coffee (s) prepackaged in pods.

  A large number of such pods has been described in the literature, among which several packaging technologies have been developed. There may be mentioned pods formed by imprisonment ground coffee packed or not between two sheets of filter paper as described in US-A-5012629 and EP-A-0583210.

  There are also pods consisting of a perforated rigid plastic cassette within which is enclosed a specific amount of ground coffee as described in WOA-2004/087529.

  There are finally pods constituted by packing under vacuum or inert atmosphere of ground coffee in hermetic cartridges of plastic or metal, said cartridges being adapted to be perforated by contending tools arranged inside a coffee machine so to allow the pressure infusion of the coffee contained in the cartridge and the distribution of the drink thus prepared. Such cartridges are especially described in EP-A-1440909, WO-A-2004/006740 or EP-A-0554469.

  The different types of coffee pods described above have the major disadvantage of being used only with a machine specifically designed to work with this type of pod or particular cartridge.

  Indeed, with the growing demand from private consumers for products allowing the preparation of espresso type coffee with automatic individual machines no longer requiring the manual measurement of the quantity of ground coffee and water as with the traditional machines. filter coffee or percolators, producers of ground or even freeze-dried coffee, as well as coffee machines, have developed their own coffee pod or coffee cartridge systems, as well as the machines for using them, exclusively competing pods or cartridges.

  Thus the consumer is thus forced, if he wants to use a particular pod, to buy the corresponding machine, which proves particularly restrictive both financially because these machines are often expensive, but also in which concerns the supply of pods, which are often marketed by specialized stores or by specific mail-order circuits.

  Another disadvantage of existing coffee pods is that they, and the machines to use them, are not suitable for use in communities or businesses, or in commercial beverage outlets because of the cost of pods, correlated with the very large number of coffees and coffee drinks prepared daily in such places. In addition, the machines operating with current pods require the filling of a limited capacity water tank, of the order of a few deciliters to a few liters, which again is inappropriate for use in communities.

  That is why the coffee machines used in local authorities, companies or professional drinking places are still of the type called "all-automatic" dispensers that are directly connected to the water supply network and have a very important reservoir. ground coffee, ground coffee, freeze-dried or concentrated, allowing the daily preparation of a large number of coffees and coffee-based drinks without refilling the tank.

  These "all-automatic" machines are adapted to perform, following a single command action of a user, in general the pressing of a button located on the machine, the set of operations for preparing a dose of coffee ground, freeze-dried, or concentrated corresponding to the amount of coffee necessary for the preparation of the desired beverage, placing this dose of coffee in an infusion chamber, settling and infusing this dose with hot water dispensing the thus prepared beverage in a suitable container outside the machine and, if appropriate, removing the dose of brewed coffee (the marc) from the brewing chamber to allow a new cycle of preparation.

  An object of the present invention is to provide a ground coffee pod "universal", that is to say that allows the preparation of coffee-based coffee beverage using "all-automatic" type coffee machines described previously.

  The present invention relates more particularly to a ground coffee pod adapted for the preparation of coffee and coffee-based beverages using "all-automatic" machines of the type described in European patent applications EP-A-0 948 927 and EP -AO 948 926, shown schematically in Figures 1 and 2 appended to the present application, or in WO-A-01/91620, and comprising an "extraction" group comprising an infusion chamber in which a quantity of ground coffee is poured, then packed and infused by at least one piston movable in said infusion chamber, said piston being connected to the boiler of the machine and having means for injecting hot water through the ground coffee after settling in the bedroom.

  Another object of the present invention is to provide a ground coffee pod for machines of the aforementioned type which can be produced industrially and for a low cost.

  Another object of the invention is to provide a coffee pod that requires little or no structural changes to these machines to be used.

  An object of the invention is finally to provide a coffee pod that can be used in said machines without manual intervention of the user to put said pod in place in the machine, and which can instead be stored in a tank integral or independent of said machine and automatically inserted from said reservoir in the extraction unit of said machine for the preparation of a coffee and then automatically removed from that after infusion of coffee contained in said pod.

  The various objects of the invention are achieved by means of a coffee pod useful especially for automatic machines for preparing and dispensing coffee-based beverages of the type described above, which comprises a determined quantity of ground coffee compacted in form. an aggregate of ground coffee beans, said pod having an outer shape adapted to the rolling, and preferably a form comprising at least one rounded portion, more preferably a substantially spherical ball shape.

  Such a pod is particularly advantageous for the preparation of coffee-based beverages, especially espresso type drinks, using an automatic machine because of its extremely simple constitution, and its singular shape. Indeed, such an aggregate compacted ground coffee is sufficiently consistent to break only under a very large compression force compared to its weight, which in combination with its rounded shape allows it to roll on itself without itself to break, and thus to be easily put in place, without manual intervention of the man, in the infusion chamber of a said automatic machine from a storage compartment connected to the latter by a simple pipe or chute diameter slightly higher than that of the pod.

  In addition, once in said chamber, said coffee aggregate is then disintegrated and packed like a dose of traditional ground coffee under the force of the compacting piston of the automatic machine, which also avoids modifying the existing machines to use pods of the invention.

  In an advantageous embodiment, the pod of the invention comprises an envelope consisting of at least one sheet or a film comprising a porous or soluble material trapping and conforming to the shape of said compacted coffee aggregate. This casing has the advantage of preventing any crumbling of the compacted ground coffee aggregate before it is introduced into the brewing chamber of the machine while improving the storage capacity of the pods without reducing their breaking capacity. and crushing under the force of the piston of the automatic coffee machine, nor preventing infusion and extraction of coffee for the preparation of a drink.

  Such a porous film or sheet preferably comprises a woven or non-woven material comprising natural fibers and / or synthetic food materials, in a grammage of between 15 and 20 g / m 2, which gives the envelope and therefore the pod a good wettability and weldability to bind the wrap around the compacted coffee aggregate.

  In this case, said envelope will preferably be made of paper based on cellulose fibers and fibers of at least one plastic material, for example a filter paper for food use.

  In a preferred embodiment, said envelope comprises zones of weakness, distributed regularly and evenly uniformly over the periphery of said pod, such areas of weakness being particularly advantageous in that said envelope is thus able to break at said zones of weakness under a compressive force at least equal to the pressure applied by a so-called settling piston inside the infusion chamber of a so-called "fully automatic" coffee machine.

  These zones of fragility of the envelope advantageously favor "the explosion" of said envelope in several fragments in the brewing chamber of the coffee machine under the pressure of the piston, thereby improving the homogeneity of the infusion and extracting the components of the ground coffee contained in the pod.

  Preferably, said zones of fragility of the envelope consist of zones of reduced thickness of the material of the envelope, and / or zones comprising additional micro-perforations of said envelope.

  In another preferred embodiment, said envelope comprises two half-shells, preferably symmetrical, sealed to one another along a continuous junction line and peripheral to the pod, said half-shells conforming to the shape said coffee aggregate.

  This embodiment facilitates the production of said pods, and in this case, said fragility zones of the envelope may consist solely in said junction line of the two half-shells forming said envelope.

  In an alternative embodiment of the pod according to the invention, said compacted ground coffee aggregate is coated with an envelope comprising a solid, and preferably soluble, food-coating composition. This embodiment is not suitable in principle for the manufacture of pods for the preparation of coffee-only beverages, but allows on the other hand to make beverages comprising coffee mixed with another component such as milk or sugar by for example, which could easily enter said coating composition.

  Whatever the embodiment of said selected pod, the amount of compacted coffee forming said aggregate is between 5 g and 12 g, preferably between 5 g and 8 g. Such a quantity of coffee corresponds to the average amount of coffee necessary for the preparation of an espresso type coffee using an "all-automatic" coffee machine.

  In addition, it will be ensured that the density of the ground coffee constituting said coffee aggregate is between 0.65 and 0.75 kg / dm 3, preferably between 0.68 and 0.72 kg / dm 3, and that that the diameter of the pod formed is of the order of 24 to 34 mm, and preferably of the order of 26 to 30 mm. These values correspond to the density and diameter limit values for which satisfactory results, that is to say at least as good as with unpacked ground coffee, have been obtained for the preparation of beverages with machines "all -automatic "in terms of taste of the prepared drinks and operation of the machine.

  Preferably, in order to obtain a pod whose introduction into the extraction unit of the automatic coffee machine is facilitated, pods of substantially spherical, cylindrical or ovoid shape are preferred, which gives good drying properties. bearing said pods, and therefore a good capacity for placement in the brewing chamber of the coffee machine and crushing under the force of the piston of said machine.

  In a manner complementary to that which has just been described, the subject of the present invention is also a process for the preparation of a coffee pod according to the invention according to which, in a first step, a determined quantity of non-ground coffee is prepared. packed, then in a second step, said amount of ground coffee is compacted to form a solid coffee aggregate of preferably rounded shape, suitable for rolling.

  Then, in a third step, said solid coffee aggregate is covered and trapped by means of an envelope conforming to the shape of said aggregate, said envelope preferably consisting of two half-shells of a porous solid material sealed with to one another, or a solidified food coating composition on said aggregate.

  Advantageously, during the second step, the ground coffee is compacted between two impressions of a mold, preferably symmetrical, until the desired coffee density is obtained, preferably between 0.65 and 0.75 kg / dm3, more preferably between 0.68 and 0.72 kg / dm3.

  When said envelope covering the coffee aggregate is formed by two half-shells, they are preferably sealed to one another by heat-sealing along a said junction line.

  In a preferred embodiment, said zones of weakness are achieved by localized weakening of the mechanical strength of said envelope after placing it around said aggregate, preferably by decreasing the thickness of said envelope or by micro mechanical or physical perforation thereof.

  In order to improve the productivity of the process, it is possible to carry out said second and third steps thereof simultaneously.

  The use of a coffee pod according to the invention for the preparation of a coffee-based beverage is simple and easy, all the operations being carried out automatically in the coffee machine as with a dose of ground coffee. Bulk "and as indicated below: - said pod is introduced into said infusion chamber of said automatic coffee machine, - said pod is compressed inside said brewing chamber until rupture of its said envelope and crushing of said aggregate of ground coffee contained therein, - injecting a predetermined quantity of hot pressurized liquid, preferably water, through ground coffee and crushed casing, and said casing and the brewed coffee are evacuated from said infusion chamber, said beverage being recovered outside said chamber in a suitable container.

  Other features and advantages of the present invention will emerge more clearly on reading the description which follows, given in an illustrative and nonlimiting manner, with reference to the appended drawings in which: FIG. 1 schematically represents a coffee machine "all- automatic "of the type described in EP-AO 948 926 and for which a coffee pod according to the invention is intended, the piston and the brewing chamber are in the rest position; Figure 2 shows the coffee machine of Figure 1 with the brewing chamber and the piston in operating position for the preparation and dispensing of a coffee-based beverage; Figures 3A to 3G show the successive steps of a method of manufacturing a coffee pod according to the present invention; FIGS. 4A to 4C show schematically the steps for preparing a coffee-based beverage from a coffee pod prepared according to the process of FIGS. 3A to 3G, and in an "all-automatic" type coffee machine. as shown in FIGS. 1 and 2.

  The present invention aims to provide a pod of ground coffee suitable for use in coffee machines type "fully automatic" currently existing, without structural modification of these machines.

  Such a machine 1, an example of which is shown in FIGS. 1 and 2, comprises an extraction unit comprising an infusion chamber 2 rotatable about an axis 6, between a first so-called rest position (FIG. 1). , and an operating position (Figure 2).

  The infusion chamber 2 consists of a cylinder open at its upper end 22 and from the bottom of which extends a cannula 2. Inside said chamber, is positioned a filtration device comprising a support plate 3 on which rests a perforated grid 4 allowing the passage of liquid but retaining the ground coffee beans.

  The support plate 3 comprises, on its periphery, a seal 5 in contact between the side walls of the chamber 2 and the plate, as well as at least one opening 31 in its body under the grid 4, this opening allowing the flow of liquid coffee from the interior of the chamber to the cannula 2, This cannula 2, allows the evacuation of the liquid coffee brewed inside the chamber 2 towards the outside thereof and its distribution of the coffee in a suitable container 16, disposed outside the machine, through a funnel 14, disposed under the cannula 21, and a chute 15 extending from said funnel to the container 16.

  The chamber 2 is secured to a support block 7, crossed by the axis of rotation 6 of the chamber, said block comprising a shaft 8 extending in the longitudinal axis of the brewing chamber 2, this shaft 8 being connected at its lower end to an actuating device for triggering the rotation of the chamber between its two respective positions of rest and operation. In the example shown in FIGS. 1 and 2, said actuating device is constituted by a connecting rod 18 and a cam 17 coupled to a motor (not shown), said connecting rod being connected at one end to the cam and at its other end to the shaft 8 of the support block 7 of the brewing chamber 2. However, any other type of actuating device can be used.

  In the rest position (FIG. 1), the chamber 2 is positioned in alignment with a ground coffee tank 13, possibly connected to a coffee mill, not shown, comprising means, also not shown, for dosing the quantity coffee to introduce into the room for the preparation of a coffee, for example a coffee type "espresso".

  Following a control action from a user, such as the insertion of coin or token into the machine or the selection of a control button, the tank 13 pours a dose of ground coffee 12 "in bulk "inside the chamber 2 on the grid 4 of the filtration device at the bottom thereof. The actuating device 17, 18 then causes (FIG. 2) the rotation of the chamber 2 about the axis 6, so as to bring it into alignment with a piston 9 for compacting and soaking the ground coffee contained in the room 2.

  This piston 9 is connected to the boiler of the machine by ducts, not shown in the figures, and comprises through its bearing face of the orifices 10 of water diffusion. In addition, said piston 9, which is advantageously of cylindrical shape and of a diameter substantially equal to the internal diameter of the infusion chamber 2, has on its periphery a seal 11 adapted to seal between the walls of the chamber 2 and the piston during the preparation of a coffee, and thus avoid splashes out of the chamber during the injection of hot water under pressure in the coffee.

  As shown in Figure 2, the piston 9 is inserted along its axis in the chamber 2 and packs the ground coffee 12 against the filter 4 of the chamber. When the coffee is packed, the piston is held in position in the chamber and water 19 is then diffused under pressure, traditionally between 8 and 12 bar, through the orifices 10 of the piston 9 through the ground coffee 12 to achieve infusion of it and the preparation of a liquid coffee.

  Under the pressure effect of the water diffused through the piston, the infused liquid coffee then flows through the orifices of the filter 4 and the orifice 31 of the support tray at the bottom of the chamber towards the cannula 21, which is directed towards the interior of the funnel 14. The coffee then flows through the chute 15 to the container 16 on the outside of the machine where the user can then enter the container containing his just prepared coffee.

  The infused coffee (marc) is then automatically discharged in the form of a moist coffee cake.

  The coffee pod according to the invention aims to replace the doses of ground coffee 12 prepared and deposited in each cycle of coffee preparation using a machine as described above.

  The basic objective of the invention is to provide a pod that can be stored and placed automatically inside the diffusion chamber, similar to a dose of ground coffee in bulk. , without structural modification of the machine, in particular of the extraction unit and, more particularly, of the infusion chamber 2 and the piston 9.

  To this end, the invention provides a pod in the form of an aggregate of compacted ground coffee trapped in a sealed envelope around said coffee aggregate or formed by coating it with a composition food. Said pod advantageously has a rounded shape adapted to allow it to roll from a compartment or storage tank for example to the inside of the brewing chamber 2 of the extraction unit of a fully automatic coffee machine.

  In addition, the envelope of the pod is advantageously adapted to break in the infusion chamber of the machine under the compression effect of the piston 9, thereby freeing the compacted ground coffee contained in the envelope and allow the preparing a liquid coffee in a manner identical to the preparation of a coffee based on a dose of ground coffee in bulk.

  In a preferred embodiment, the pod according to the invention is advantageously in the form of a substantially spherical ball or ball composed of a ground coffee aggregate covered with an envelope made of filter paper of the type traditionally used for manufacture of tea bags for example.

  With reference to FIGS. 3A to 3G, such a pod is produced in a simple and rapid manner from a fixed quantity of unpacked ground coffee 12, preferably between 5 and 15 g depending on the volume of liquid coffee to be prepared, and preferably of the order of 7 to 8 g for the preparation of an espresso type coffee.

  This dose of unpacked coffee 12 (FIG. 3A) is deposited in a mold consisting of two hemispherical imprints 20a, 20b (FIG. 3B). The dose of ground coffee is then compacted between said mold cavities 20a, 20b under an IF pressure, so as to form a solid and compact ground coffee ball or sphere 12a, this compacted coffee ball 12a having a density between 0.68 and 0.72 kg / dm3 for a mass of unpacked ground coffee of between 5 and 12 g, the normal density of unpacked ground coffee being of the order of 0.40 kg / dm3.

  This compacted coffee ball 12a is then covered with a filter paper envelope formed by pressing and heating localized two sheets of filter paper 23a, 23b around the coffee ball 12a, between two indentations 21a, 21b, also hemispherical of a second mold. These imprints 21a, 21b are identical to the imprints 20a, 20b of the first mold used to form the compacted coffee ball 12a, except that these comprise heating means 22, for example resistive heating means, for heating the rim. upper of said fingerprints.

  As represented in FIGS. 3E and 3F, the wrapping of the coffee ball 12a is carried out by positioning a sheet of filter paper 23a, 23b between the ball 12a and a said imprint 21a, 21b of the second mold, which are then brought closer together from each other and tightened with a force FI identical to the compacting force of the ball 12a in the first mold, thereby forcing the plating of each sheet 23a, 23b all around the compacted coffee ball 12a. The heating means 22 of each cavity 21a, 21b make it possible at the same time to heat-seal the sheets of filter paper 23a, 23b, one with the other, and thus to close the envelope 23 of the pod around the compacted coffee ball along a continuous weld line and peripheral to it. In order to facilitate the welding of the filter paper sheets, it is preferable to use a paper comprising polyethylene or polypropylene fibers and a grammage of between 15 and 20 g / m.sup.2, the plastic fibers being melted under the effect of heating. applied by the heating means 22 of the indentations 21a, 21b in the second mold.

  This gives a pod 12b of compacted ground coffee packaged in a filter paper envelope 23.

  In a complementary manner, in order to further reduce the breaking strength of the casing 22 of the pod, it is possible to produce, on said casing, localized zones of weakness at the level of which said casing will tear in a privileged manner under the force of the casing. piston 9 inside the infusion chamber of an "all-automatic" coffee machine. Such areas of weakness may for example consist of areas of reduced paper thickness or micro perforations made through the paper sheets 23a, 23b before being placed around the spherical coffee aggregate 12a and welding.

  However, since the solder line of the paper sheets alone already constitutes a zone of weakness likely to give way under the pressure implied by the piston 9 of an all-automatic coffee machine 1, it is possible to be content with of this weld line as a zone of weakness of the envelope.

  In an alternative embodiment of the pod according to the invention, it is possible to replace the filter paper envelope with a wrap constituted by two sheets of a film based on NYLON fibers (registered trademark) woven, both said sheets. being welded identically to the filter paper sheets 22a, 22b around the spherical compacted coffee aggregate 12a to form the envelope of the coffee pod 12b according to the invention.

  In another embodiment, the pod according to the invention can be made in the form of a capsule, the envelope 22 of said pod being constituted by two half-shells of thin plastic food material, for example polyethylene or polypropylene, said half-shells being welded to each other along their peripheral edges or sealed in the manner of drug capsules by insertion and snapping of their said flanges one on the other; said ground coffee aggregate 12a being thus encapsulated between the two half-shells of the envelope.

  In the case where the pod 12b has a shell "shelled", it will also perform on this envelope fragile areas promoting the rupture thereof in the brewing chamber 2 of a fully automatic coffee machine. These areas of weakness may be of the same type as those made on paper filter envelopes or NYLON (trademark).

  Finally, it is also conceivable to make the envelope of said pod according to the invention, by coating a compacted coffee aggregate 12a in the form of a ball, using a food composition based on sugar, coffee or even milk, pods thus produced for the preparation of coffee-based beverage such as sweet coffee, coffee latte or cappuccino, for example.

  As shown diagrammatically in FIGS. 4A to 4C, the coffee pod 12b made according to one of the embodiments described above, allows the preparation of coffee-based beverages using an all-automatic coffee machine 1 " as for example shown in Figures 1 and 2.

  The pod 12b coated with its envelope 23 is introduced into the brewing chamber 2 of the machine from a not shown storage tank, the spherical shape of said pod allowing it to roll from said compartment to the inside of said chamber, for example by flowing in a feed chute opening into said infusion chamber. The pod thus falls into the chamber and is placed on the bottom thereof against the filtering grid 4 above the support plate 3.

  Once the pod positioned in the chamber, a piston 9 is inserted inside the chamber and compresses said pod against the grid 4 at the bottom of the chamber under a force F2, this compression force applied by the piston on the causing depression, as shown in Figure 4B, the rupture of the casing 23 of said pod at the said fragile areas thereof and the formation of envelope fragments 23c mixed with ground coffee 12 previously contained in the inside of the envelope in the form of an aggregate 12a.

  Once the end of the stroke of the piston 9 is reached inside the chamber, the latter is held in position inside the chamber, and hot water 24 is injected into said chamber under pressure. of the order of 8 to 12 bar depending on the machine models, from the boiler of the coffee machine via the piston 9, which comprises diffusion ducts 91 and dipping orifices 10. This water under pressure diffuses through the ground coffee 12 (and fragments 23c of the envelope) and infuses it, the infusion juice (liquid coffee) flowing from the chamber, through the filter 4 and the orifices 31 from the filter support plate 3 to a container 16 located outside the machine for receiving the beverage.

  Once the coffee 12 is fully brewed inside the chamber 2, and the liquid coffee 25 has flowed into the container 16 outside the machine, the piston 9 is removed from the brewing chamber and the coffee grounds mixed with the envelope fragments 23c of the pod 12b is discharged from the chamber to a storage compartment of the grounds to allow the preparation of a new beverage in the machine.

  It is thus possible to produce coffee and coffee-based beverages from 30 pods 12b of prepackaged ground coffee which is "exploded" inside the brewing chamber 2 of a fully automatic type machine, said machines requiring no structural modification to use said pods.

  Advantageously, said coffee pods 12b may have different diameters, advantageously comprised on average between 24 and 32 mm, and preferably between 26 and 30 mm, depending on the ground coffee mass contained in the pod. Such a pod diameter is adequate for the use of the pod with "all-automatic" machines, the diameter of the infusion chamber of the latter being generally between 30 and 35 mm.

  The present invention has been described herein in preferred embodiments in connection with a particular type of coffee machine, for which the pod of the present invention has been designed. However, the scope of the present invention is not limited to the embodiments described but extends to slight variations that may be obvious to those skilled in the art, particularly with regard to the shape of the pod, which may be considered ovoid or even cylindrical, low height, or the variations of materials constituting the envelope of said pod.

Claims (1)

18 Claims   1. Coffee pod (12a, 12b) useful in particular for automatic machines (1) for preparing and dispensing coffee drinks of the type comprising at least one infusion chamber (2), and at least one piston of settling (9) of a determined quantity of ground coffee (12) introduced into said brewing chamber, characterized in that it comprises a determined quantity of ground coffee compacted in the form of an aggregate of ground coffee beans (12a ), said having an outer shape adapted to rolling, and preferably a shape comprising at least one rounded portion, more preferably a substantially spherical ball shape.   2. Pod according to claim 1, characterized in that it comprises a casing (23) consisting of at least one sheet or a film of porous or soluble material trapping and conforming to the shape of said compacted coffee aggregate (12a).   3. Pod according to claim 2, characterized in that said casing comprises a woven or non-woven material comprising natural fibers and / or synthetic food materials in a basis weight between 15 and 20 g / m2.   4. Pod according to one of claims 1 to 3, characterized in that said casing is made of paper based on cellulose fibers and fibers of at least one plastic material, for example a filter paper for food use.   5. Pod according to one of claims 2 to 4, characterized in that said envelope comprises zones of fragility, preferably distributed regularly and uniformly on the periphery of said pod, said envelope being able to break at said areas of fragility under a compressive force at least equal to the pressure applied by a said tamping piston (9) inside the infusion chamber (2) of a said automatic coffee machine (1).   6. Pod according to claim 5, characterized in that said areas of fragility of the envelope consist of areas of reduced thickness of the material of the envelope, and / or zones comprising additional micro perforations of said envelope .   7. Pod according to one of claims 2 to 6, characterized in that said envelope comprises two half-shells (22a, 22b), preferably symmetrical, sealed to one another along at least one line continuous and peripheral junction to the pod, said half-shells conforming to the shape of said coffee aggregate (12a).   8. Pod according to claim 7, characterized in that said zones of weakness consist in said junction line of the two half-shells forming said envelope.   9. Pod according to claim 1 or 2, characterized in that said compacted ground coffee aggregate is coated with an envelope comprising a solid, and preferably soluble, food-coating composition.   10. Pod according to one of claims 1 to 9, characterized in that said amount of compacted coffee is between 5 g and 15 g, preferably between 5 g and 8 g.   11. Pod according to one of claims 1 to 10, characterized in that the density of the ground coffee constituting said coffee aggregate is between 0.65 and 0.75 kg / dm3, preferably between 0.68 and 0.72 kg / dm3.   12. Pod according to one of claims 1 to 11, characterized in that it is substantially spherical shape, cylindrical or ovoid.   13. Pod according to claim 12, characterized in that the diameter of said pod is of the order of 24 to 34 mm, preferably of the order of 26 to 30 mm.   14. Process for the preparation of a coffee pod according to one of claims 1 to 13, characterized in that in a first step, a determined quantity of unpacked ground coffee (12) is taken, then, in a second step said amount of ground coffee is compacted to form a solid coffee aggregate (12a) of preferably rounded shape, suitable for rolling.   15. Method according to claim 14, characterized in that in the second step, the ground coffee is compacted between two impressions of a mold (20a, 20b), preferably symmetrical, to obtain the desired coffee density, preferably between 0.65 and 0.75 kg / dm3, more preferably between 0.68 and 0.72 kg / dm3.   16. Method according to one of claims 14 or 15, characterized in that in a third step, covers and traps said solid coffee aggregate (12a) with a casing (23), matching the shape said aggregate, said envelope being preferably made of a porous solid material, or a food coating composition.   17. The method of claim 16, characterized in that said envelope consists of two said half-shells (23a, 23b) sealed to one another by heat-sealing along at least one said junction line. .   18. Method according to one of claims 14 to 17, characterized in that said zones of weakness are achieved by localized weakening of the mechanical strength of said envelope after placing it around said aggregate, preferably by decreasing the thickness of said envelope or by mechanical or physical micro-perforation thereof.   19. Method according to one of claims 14 to 18, characterized in that said second and third steps are performed simultaneously.   20. Use of a coffee pod according to one of claims 2 to 13 for the preparation of a coffee-based beverage, characterized in that: - said pod (12a, 12b) is introduced into said coffee chamber; infusion (2) of said automatic coffee machine (1), - said pod is compressed inside said brewing chamber until breakage of said casing (23) and crushing of said aggregate of ground coffee contained in this, - a given amount of hot pressurized liquid (24), preferably water is injected through the crushed ground coffee and the casing, and said casing and the brewed coffee are discharged from said chamber. infusion, said beverage being recovered outside said chamber in a suitable container (16).