Coffee extraction method and device implementing the above method

Abstract

A coffee extraction method comprising a process for pressing a predetermined volume of water so as to force it through a first confined volume (VI ) containing coffee powder against a movable septum (MS ) loaded by a resilient element ( SPR), wherein the predetermined volume of water is such that a pressure value within the first volume is determined by a retraction of said movable septum.

Description

[0001] COFFEE EXTRACTION METHOD AND DEVICE IMPLEMENTING THE ABOVE

[0002] METHOD

[0003] Field of the invention

[0004] The present invention relates to the field of methods for extracting liquid cof fee from ground cof fee powder and in particular to the field of manual and automatic cof fee machines .

[0005] State of the art

[0006] There are many methods for extracting a liquid beverage from ground cof fee . The following are known state-of-the- art methods :

[0007] - infusion, in which the ground co f fee is simply infused in hot water and then filtered through metal mesh or paper filters ; high-temperature , high-pressure water extraction, in which the ground cof fee is placed in a container equipped with a filter on one side and water is passed through it . This water is heated to a boil , thus providing suf ficient pressure to overcome the resistance of the compacted ground cof fee ;

[0008] - extraction using water at a temperature below boiling point and at a pressure high enough to allow the compacted ground coffee to pass through. The water is forced through by a piston or a water pump that pushes the water through the appropriately compacted ground coffee.

[0009] All of these methods are valid in principle but difficult to repeat. Indeed, the final result depends on a multitude of variables that are difficult to control on a daily basis. Among these, we can mention:

[0010] - the degree of roasting of the coffee, which the more roasted it is, the more it allows water to flow, but at the cost of a greater loss of volatile compounds that give the beverage its flavour; the grain size of the ground coffee, which directly affects the resistance to the passage of water and which is combined with; the temperature and pressure of the hot water, which determine the degree of extraction but which depend somewhat unpredictably on the combination of grain size and roasting of the coffee.

[0011] In fact, the resistance to the passage of water determines the pressure, or rather the counterpressure at the pressure source, which can be a boiler, a piston, or a pump.

[0012] The counterpressure needed to overcome the resistance offered by the compacted coffee powder, in the case of the boiler, also affects the temperature reached by the water, being biunivocally linked to the pressure .

[0013] Piston and pump solutions prove to be the most ef ficient , as the water temperature and water pressure are independent variables . While pressure is always linked to the counterpressure provided by the cof fee powder, the temperature is at least set in various ways by the machine . Many cof fee machines , in which the pressure source is a pump, work with capsules or pods in which the grain size and roasting degree of the coffee is controlled by the manufacturer of the machine itsel f to adapt to the characteristics of the machine .

[0014] In fact , while water pressure can be independent of water temperature , it is not independent of the characteristics of the contents of the pods and capsules .

[0015] Therefore , cof fee machine manufacturers themselves take care to control the characteristics of the pods used in their machines to ensure good results .

[0016] Grain si ze and roasting are aspects on which manufacturers can intervene to adapt to the characteristics of the machines produced and marketed .

[0017] We believe this situation can be improved .

[0018] Unless speci fically excluded in the detailed description below, the information provided in this chapter is to be considered an integral part of the detailed description . Summary of the invention

[0019] The purpose of the present invention is to present a coffee extraction method that is at least alternative to known methods .

[0020] The basic idea of the present invention is to extract cof fee by forcing water through a volume filled with coffee powder, acting against a movable septum loaded by a resilient element .

[0021] Therefore , a first volume containing the cof fee powder is identi fied, along with a second volume communicating with the first volume and designed to receive the water that passes through the first volume by retracting the movable septum, which separates the first volume from the second volume .

[0022] The cof fee contained in the first volume does not need to be pressed in any way, but simply released, so as not to contribute to the backpressure provided by the resilient element acting on the movable septum .

[0023] Advantageously, the pressure is only marginally af fected by the characteristics of the cof fee powder, and more importantly, it is not af fected in any way by temperature . Therefore , ignoring the fact that it is a dynamic process , it can be stated that , ideally, the backpressure depends only on the reaction of fered by the movable septum loaded by the resilient element.

[0024] If we consider that a cup of coffee is of the order of 60 ml, forcing 60 ml to pass over the course of 10-15 seconds, we can assume that the process is quasi-static and therefore, the backpressure is primarily determined by the calibration of the resilient element.

[0025] In other words, it is desired to create a highly repeatable method that is little influenced by other factors, so that the backpressure depends almost exclusively on the reaction force of the resilient element associated with the movable septum. This, for example, is one of the reasons why it is best not to press the ground coffee into the relevant volume, as this would affect the backpressure. The powder should simply be deposited in its housing.

[0026] Any additional disturbances, such as friction of the septum against the walls, can be compensated for by an appropriate choice of resilient element.

[0027] For example, the amount of water forced through the powder may also be measured, i.e., predetermined. Otherwise, if it were excessive, once the movable septum reached its end stop, the pressure would necessarily increase, as it is no longer is determined essentially by the reaction force of the septum.

[0028] US2014356501 shows a method of extracting coffee from a pod . In this solution, the piston is loaded by a spring that allows it to retract . However, the spring has no ef fect on the liquid . Therefore , once the liquid has passed through the pod, the spring causes the piston to retract without af fecting the liquid in the chamber opposite the piston .

[0029] The present extraction method is capable of making the percentage of soluble substances extracted and the creation of foam independent of the quantity of cof fee , the degree of grinding and roasting of the powder, and the manual compression of the powder itsel f , which is normally performed precisely when preparing espresso .

[0030] Advantageously, a controlled and nearly constant pressuri zation level allows the C02 extracted from the cof fee , which is always roasted to some degree and therefore porous , to remain dissolved . Roasting, being a combustion process , produces both C02 and the porous structure of the cof fee granules , similar to activated carbon, which partially absorbs it . This C02 , which only becomes desaturated at the end of extraction, when the liquid stops being pressed, is responsible for the creation of a dense foam . This foam is what is commonly called " cream" and is typical of espresso cof fee .

[0031] According to the invention, after all the water has passed through the first volume , the pressuri zed water source ceases its ef fect and the resilient element is arranged to push the water back . The water can then be forced through the ground cof fee again or released into a cup .

[0032] Advantageously, the water passes through the first volume at least twice .

[0033] However, according to the present invention, the water can be forced through the first volume any number of times . Therefore , the extraction of the substances contained in the ground cof fee is achieved at a temperature lower than the boiling temperature of water and through two or more water crossings .

[0034] According to a preferred aspect of the invention, the predetermined volume of water, once forced through the first volume , can be kept pressuri zed for a settable time by blocking the flow, and then forced by the resilient element to pass through the first volume again to be poured into the cup .

[0035] The present invention also relates to various devices that implement the method described above .

[0036] The water is stored in a third volume or reservoir . It can be heated in the third volume or can be heated in a conduit connecting the third volume to the first volume .

[0037] Alternatively, the water can be heated separately and introduced into the third volume to be then forced through the first volume .

[0038] The present invention is suitable for both the creation of fully manual household machines and for the creation of bar or automatic machines .

[0039] The dependent claims describe preferred variants of the invention and form an integral part of this speci fication .

[0040] Brief description of the figures

[0041] Further purposes and advantages of the present invention will become clear from the following detailed description of an embodiment thereof ( and its variants ) and the accompanying drawings , provided purely for explanatory and non-limiting purposes , in which :

[0042] Fig . 1 shows a first diagram of a cof fee machine according to a first preferred variant of the invention;

[0043] Fig . 2 shows a detail of the cof fee extraction unit of the machine of Figure 1 without the lever structure required to provide force to the piston .

[0044] Fig . 3 shows an exemplary diagram of the extraction method steps for the machine of Figure 1 .

[0045] Figs . 4 and 6 show two additional diagrams of co f fee machines according to two preferred variants of the invention .

[0046] Fig . 5 shows a construction detail of some parts of the machine of Fig. 4.

[0047] Figs. 7a and 7b show two views, one in section and one from above, respectively, of a construction element of the machine of Fig. 6.

[0048] The same reference numbers and letters in the figures identify the same elements, components, or functions.

[0049] It should also be noted that the terms "first," "second," "third, " "upper, " "lower, " and the like may be used here to distinguish various elements. These terms do not imply a spatial, sequential, or hierarchical order for the modified elements unless specifically indicated or inferred from the text .

[0050] The elements and features illustrated in the various preferred embodiments, including the drawings, may be combined with each other without departing from the scope of this application as described below.

[0051] Detailed description of preferred embodiments

[0052] All figures show coffee machines implementing the method of the present invention.

[0053] Fig. 1 schematically shows a machine in which a pressure source is provided by a piston P.

[0054] The piston can be operated manually or by an electric motor .

[0055] The extraction unit, shown in detail in Figure 2, can be separated from the machine structure to allow the extracted cof fee to be poured .

[0056] The machine comprises a casing H, to which the piston is slidably coupled, in which a first volume VI is arranged to accommodate cof fee powder CP .

[0057] The first volume borders and is separated from a second volume V2 by a sealed movable septum MS , hereinafter referred to as the "movable septum" , loaded by a resilient element SPR . The movable septum can be sealed by a perimeter gasket adhering to the perimeter walls defining the second volume V2 .

[0058] It is preferable that the casing H and other components be cylindrically symmetrical to simpli fy coupling .

[0059] The resilient element , for example , is a spiral spring that pushes the movable septum toward the first volume in a predetermined position .

[0060] This predetermined position can be achieved, for example , by a contact ring (not shown) attached internally to the cylinder .

[0061] In the variant shown in Fig . 1 , in which the water is compressed by the piston P, there is a third volume V3 , which borders the first volume VI , so that the piston compresses the water in the third volume , forcing it to pass through the first volume and reach the second volume V2.

[0062] The piston P, together with the third volume, defines a source of pressurized water.

[0063] Since the third volume has a fixed size, the water content also has a predetermined volume, larger than the first volume containing the ground coffee.

[0064] The compression movement of the piston causes the volume of water to pass through the first volume against the movable septum; therefore, the water passes through the first volume and partially reaches the second volume.

[0065] Retraction of the piston causes the movable septum, returning to its rest position, to push the water back through the first volume as long as it reaches the third volume. Therefore, the third volume at this stage contains liquid coffee.

[0066] Since the water flow passes through the first volume in two opposite directions, a first port can be identified between the first and second volumes, and a second port between the pressurized water source and the first volume. Furthermore, a third port connects the first, second, or third volumes to the outside environment to collect the liquid coffee in a cup. The second and third ports can coincide. In fact, in the variant shown in Figure 1, the piston can be removed to manually pour the liquid coffee into a cup. The first port is equipped with a first filter FS1, which represents a fixed septum with filter passages.

[0067] In Figure 1, the first filter FS1 divides the first from the second volume, and the movable septum is arranged to face and preferably contact the first filter FS1.

[0068] The second door is equipped with a second filter FS2 to prevent the coffee powder from dispersing into the liquid coffee during the second passage of the coffee powder.

[0069] A tap for collecting the coffee can be provided, for example, associated with the first or third volume.

[0070] If the piston is held proximal to the second port, i.e., filter FS2, and the tap associated with the first volume is opened, the mobile septum MS compresses the liquid coffee, forcing it to pass through a portion of the first volume and through the tap. In this case, the tap defines the third port and should be equipped with an additional filter .

[0071] Alternatively, the tap can be associated with the third volume V3 and positioned near filter FS2, so that it is sufficient to move the piston away from filter FS2 enough to uncover the opening of the tap, while the mobile septum compresses the liquid coffee, forcing it to exit through the tap after having passed through the first volume at least a second time. A cycle includes an advancement and subsequent retraction of the piston . According to a variant of the invention, multiple cycles can be performed before collecting the liquid cof fee .

[0072] In Fig . 1 , the second and third ports coincide , and therefore the second filter appears as a second fixed septum separating the first from the third volume .

[0073] From the described configuration, it is clear that the first volume is intermediate between the second and third volumes .

[0074] The water can be heated in the third volume using an electric resistor or can be introduced into the third volume V3 , previously heated in a known manner .

[0075] The piston P is preferably equipped with a vent valve VC that eliminates any air cushion between the free surface of the water and the piston .

[0076] Fig . 1 shows a manual machine implementing the solution in Fig . 2 .

[0077] The casing H is inserted into a special support S to which a lever L is hinged, arranged to act on the piston P described in Fig . 2 .

[0078] The volume of the third volume V3 is less than the sum of the first and second volumes , but greater than the volume of the first volume VI . Therefore , the pressure inside the first and second volumes is due essentially exclusively to the action of the movable septum SM, which can preferably be calibrated to provide a pressure of 9 bar.

[0079] Therefore, the pressure inside the first volume does not depend on the force with which the lever is operated, but essentially exclusively on the calibration of the resilient element that loads the movable septum.

[0080] Preferably, the spring defining the resilient element is of the cup type, capable of maintaining a constant force exerted on the movable septum, regardless of its position. After the water pressing process, the liquid coffee can be recovered, for example, by removing the casing H from its seat in the holder S, and removing the piston from the third volume V3.

[0081] However, more convenient solutions may be available, such as a tap (not shown) as described above.

[0082] It is worth remembering here that the parameters of Italian espresso are codified by the association of the same name and defined as follows:

[0083] 1. Dose of ground coffee: 7 grams + / - 0.5

[0084] 2. Water temperature (group outlet) : 90°C + / - 2

[0085] 3. Water pump pressure: 9 bar (atm)

[0086] 4. Coffee tamping: 25 kg

[0087] 5. Extraction time: 5 seconds of pre-infusion + 25 seconds of brewing

[0088] 6. Volume in the cup (including crema) : 25 milliliters

[0089] 7. Coffee temperature in the cup: 67°C + / - 3

[0090] Figure 3 describes the liquid coffee extraction steps according to the method of the present invention:

[0091] - a: filling the first volume VI with ground coffee;

[0092] - b: supplying pressurized hot water to the first volume until the mobile septum is completely removed from the filter FS1;

[0093] - c: stopping the hot water pressurization; and: collecting liquid coffee in a cup.

[0094] For example, the sequence in Fig. 3 does not show the steps for loading the ground coffee into the first chamber, filling the third chamber with hot water, and attaching the piston to the third chamber.

[0095] Furthermore, step 3d, in which the piston is removed, is entirely optional, since, as will be described later, the system for supplying pressurized hot water may vary.

[0096] Fig. 4 shows another piston-based variant of the present invention .

[0097] The body of the device is upside down compared to the previous figures, but this is irrelevant.

[0098] The piston P is operated by a crank-and-connector system or by a linear actuator. The piston operates , as in the previous variant , in the third chamber, which can be f illed from above after removing the GC capsule assembly described below .

[0099] The third chamber V3 can be associated with an electric resistor to heat the water introduced into the third chamber, or the water must be introduced already hot . Subsequently, the capsule assembly is inserted, into which the cof fee powder is loaded, and extraction can be performed as described above .

[0100] A tap is provided for the third volume . The opening of the tap can advantageously be determined by the position of the piston inside the third volume , so that when the liquid cof fee is being discharged, the discharge port is open, while once the discharge phase is complete , the piston rises , closing the discharge port to accommodate new water . Fig . 5 shows an exploded view of the capsule assembly GC . The latter comprises

[0101] - a tubular-shaped outer body Cl , configured to enclose the first and second volumes VI and V2 , with a bottom wall defined by the filter FS 1 ,

[0102] - a tubular-shaped inner body C2 , configured to enclose the second volume V2 and therefore equipped with a bottom wall defined by the f ilter FS2 and the mobile septum MS loaded by the spring SPR, in which the inner body is configured to fit at least partially into the outer body .

[0103] As described above , it is preferable for the components to have cylindrical symmetry to s impli fy coupling, so the outer body is cylindrical in shape and has a single base defined by the FS 1 filter . The inner body is cylindrical in shape and has a closed upper base and a lower base defined by the FS2 filter .

[0104] The inner body fits securely into the outer body, for example using a thread or a bayonet fitting .

[0105] The capsule assembly can be disassembled to remove used ground cof fee and introduce fresh ground cof fee .

[0106] Once loaded with fresh ground cof fee , the capsule assembly is sealed with the casing H to perform the steps described above .

[0107] The seals G1 and G2 are also disclosed between the inner body and the outer body, and G3 between the outer body and the casing H into which the capsule assembly is intended to be inserted .

[0108] This solution is particularly convenient because it allows for very quick cof fee preparation by removing only the capsule assembly from the holder (not shown in Fig . 4 ) , rather than the entire H-shaped container .

[0109] The amount of water to be added to the H-shaped container can be indicated by a speci fic mark or by using a measuring cup . As described above, it is important that the volume of water be greater than the first volume VI and less than the sum of the volumes VI and V2 .

[0110] It is well known that at low temperatures , mainly sweet and bitter substances dissolve in water, while at high temperatures , acidic substances , particularly the "burnt" flavour left over from roasting the cof fee beans , dissolve . It is commonly believed that the optimal temperature for extracting soluble compounds , to obtain a tasty, non-acidic cof fee , is in the range of 88- 96 ° C . The of ficial espresso cof fee parameters have already been mentioned above . It should be reiterated here that the invention has the speci fic obj ective of making the extraction parameters independent of one another and o f the degree of roasting and grinding of the raw material . Precise temperature control , independent of the extraction pressure , which is controlled by the elastic water-reacting element , makes the compression of the coffee powder unnecessary . Indeed, this practice , mandatory with state-of-the-art extraction systems to create counterpressure to the water flow that generates the necessary extraction pressure , is absolutely contraindicated here . The flow of water through the powder is controlled by the speed of the piston, or the flow rate of the water pump, while the pressure is controlled by the aforementioned elastic reaction element . No compression of the powder is necessary, and the flow itsel f is also independent of the degree of roasting and grinding of the cof fee . This makes the extraction method, and the machines that perform it , particularly suitable for obtaining a good espresso from simple ground cof fee or from ground coffee contained in filter bags similar to those typically used for tea . This feature is particularly signi ficant because the solid residue of the beverage , even when contained in the bags , is easi ly and completely compostable by disposing of it in the organic waste bin .

[0111] It is worth noting that another advantage of this extraction method is that it reduces the solid residue in the liquid consumed . Since the process is not dependent on the grain si ze o f the powder, it can be ground relatively coarsely so that the filter can retain it ef fectively even after the extraction of the soluble substances has reduced its si ze . This possibility is not explored by conventional extraction methods , which rely on the powder ' s resistance to the water f low to create the necessary pressure . Therefore , they must grind the powder very finely and compress it in the filter holder . This also means that the pressure in conventional methods necessarily decreases . As the water dissolves the soluble substances , the powder reduces its size, freeing up passageways for the water to flow more freely. Advanced coffee machines attempt to control the pump, increasing its flow rate, to maintain the correct pressure, but this implies a very rapid passage of water, which reduces the percentage of extracted substances. The unique features of the proposed solution include :

[0112] - the number of times the water passes through the ground coffee, which can be set as the number of times the piston moves up and down,

[0113] - the infusion time, which can be set, once the number of passes has been determined, by adjusting the speed of the piston .

[0114] Advantageously, roasting and grind are no longer essential for maintaining extraction pressure, and therefore the method can ensure, once the parameters are adjusted, perfect extraction regardless of the ground coffee used.

[0115] The number of passes is always performed under pressure to prevent the CO2 that the water absorbs from the roasted coffee from being desorbed. Roasted coffee acts like activated carbon, also adsorbing gases derived from the roasting process. This allows the CO2 to be desorbed only during the last pass, i.e., when the liquid is released into the cup. Advantageously, by allowing the CO2 to desorb only immediately before it descends into the cup, the method guarantees a thick and persistent foam, giving the drink the typical appearance that the customer expects from espresso cof fee . According to another preferred variant of the invention, the control of the piston P drive motor can be operated so that the piston itsel f , during certain sections of its stroke , advances and retracts by very small distances , ef fectively oscillating around an equilibrium position, thus creating a vibration in the liquid that improves , as ultrasonic cleaners do , the extraction of soluble substances from the cof fee powder . This mode should preferably be implemented either during the pre-infusion period, as described above , or around its top dead center, corresponding to the maximum retraction of the mobile septum .

[0116] The mode used during pre-infus ion is also particularly suitable for preparing, as will be explained in more detail later, a beverage known as "Cuban Cof fee , " obtained by mixing powdered sugar directly with the cof fee powder in the filter holder .

[0117] Fig . 6 shows a third configuration of a machine capable of extracting cof fee from ground cof fee using the method of the present invention . It is operated by a volumetric pump VP that draws water from a separate tank V3 , which contains a water heating resistor R .

[0118] The pump sends water to filter FS2 , forcing it through the first volume VI until the mobile septum MS retracts .

[0119] The volume of water pumped is predetermined, such that the mobile septum retracts without exceeding the pressure value determined by the resilient element .

[0120] At the end of the operation, the pump stops and valve VAI opens , connecting volume VI to the outside environment to collect the liquid cof fee , while the mobile septum returns to its rest position .

[0121] I f a volumetric pump is not desired, it is necessary to monitor the position of the mobile septum so as to stop pumping when it reaches a predetermined position corresponding to the maximum pressure desired in volumes VI and V2 , which also corresponds to the predetermined volume of liquid desired in the cup .

[0122] The solution shown in Fig . 6 optionally involves heating volume V2 using a j acket arranged around it and circulating hot water from volume V3 through the j acket .

[0123] For example , in a first phase, valve VA2 is opened, connecting pump VP to j acket J constructed around volume V2 . After heating volume V2 , valve VA2 is closed and a predetermined volume of water is pumped into volume VI until the movable septum MS is at least partially retracted . Subsequently, pump VP is stopped and valve VAI is opened to collect the extracted liquid cof fee .

[0124] During the hot water circulation phase in j acket J, low- pressure hot water still reaches volume VI , thus causing a so-called pre-infusion phase , in which the ground cof fee is soaked in water but are not yet pressuri zed, which is beneficial for subsequent extraction .

[0125] The cof fee powder can be loaded in the same way as in the solution shown in Figs . 4 and 5 , using a removable capsule assembly .

[0126] It is worth noting that , according to all the variants of the invention described, the cof fee powder can be loose or collected in pods .

[0127] Collecting the powder in pods is advantageous because it ensures the correct dosage of the cof fee powder, preventing an excessive amount of cof fee from causing additional backpressure beyond the pressure generated by the resilient element coupled with the movable septum .

[0128] According to a preferred aspect of the invention, the VA2 valve can also be operated in a pulsed manner at a suitable frequency, causing a series of vibrations— micro-water hammers— which, similar to the high- frequency reciprocating motion of the piston in previous variants , can produce an additional extraction ef fect similar to that found in ultrasonic cleaners . This mode of operation can be implemented during the seconds of pre-infusion, or during a period when the mobile septum MS is in its fully retracted position, or both .

[0129] The first mode of operation is particularly interesting for creating a very unique beverage called "Cuban Cof fee . " This name corresponds to a beverage composed of sweetened cof fee with a thick, dark cream obtained by vigorously mixing sugar with the very first cof fee extract , which is rich in fatty substances . The chemical reaction between these substances and the sugar, combined with the mechanical component of the vigorous mixing, leads to the creation of a foamy, fatty, and very sweet compound that is able to float on the surface of the liquid cof fee . A wide audience appreciates this type of cof fee for the pleasure of drinking the liquid mixed with the aforementioned sweet foam . It is clear that the machine operating method, which creates strong shock waves in the liquid during the preinfusion period, is designed to create the aforementioned foamy cream by reacting with the sugar and fats from the initial extraction of the cof fee , i f a mixture of ground cof fee and ground sugar (preferably unrefined brown sugar ) is placed in the filter holder . This method creates the beverage known as "Cuban Cof fee" with no ef fort on the part of the user other than adding sugar mixed with the ground cof fee .

[0130] Figs . 7a and 7b show two views of the GC unit , which houses the ground cof fee of the machine shown in Fig . 6 . This figure illustrates how the unit is removable for convenient refilling and can be attached to the rest of the machine using a system TN that engages with inclined planes on the body of the machine , similar to a bayonet fitting . This coupling system is known from standard espresso machine cof fee holders . The inclined planes allow for a first , sealed connection between the GC unit and the machine body . The gasket GT indicates the perimeter of the first , sealed hydraulic connection created between the unit GC and the machine body .

[0131] The GC unit according to the present invention di f fers from the prior art in that it features a second, sealed hydraulic connection with the machine body, created during the translation and rotation o f the unit GC using the handle MN .

[0132] The O-ring indicates the lip of the unit GC opening used to create the second, sealed hydraulic connection with the machine body .

[0133] Comparing Fig . 7a with Fig . 6 , it is clear that the second, sealed hydraulic connection connects the unit GC to tank V3 , while the first , sealed hydraulic connection connects the unit GC to the second volume V2 described above . Implementation variations to the non-limiting example described are pos sible , without departing from the scope of protection of the present invention, including all embodiments equivalent to the claims for a person skilled in the art .

[0134] From the above description, a person skilled in the art is able to implement the invention without introducing further construction details .

Claims

CLAIMS1 . A cof fee extraction method comprising a procedure for pressing a predetermined volume of water so as to force it to cross a first confined volume (VI ) containing cof fee powder, the method being characteri zed in that said crossing is forced against a sealed movable septum (MS ) , loaded by a resilient element ( SPR) wherein the predetermined volume of water i s such that the pressure value to which the volume of water is subj ected during said passage is determined by a reaction force exerted by said movable septum that opposes the crossing .2 . A method according to claim 1 , wherein said pressing procedure is performed by mechanical compression means and wherein a temperature value of the volume of water is independent of the mechanical compression means .3 . A method according to claim 2 , wherein the mechanical compression means include a pump or a piston .4 . A method according to any preceding claim, further comprising a step of interrupting said pressing procedure , allowing said movable septum to return to a rest position so as to force the predetermined volume of water to cross the first volume again .5 . A method according to claim 4 , comprising further pressing the predetermined volume of water so as to achieveat least a third crossing through the first volume .6 . Cof fee machine comprising a body (H) containing :- a first volume (VI ) enclosed by a first and second filter ( FS 1 , FS2 ) , designed to receive and retain cof fee grounds ,- a second volume (V2 ) ,- mechanical compression means ( P, PV) arranged to press a predetermined volume of water, forcing it through said first volume , the machine being characteri zed by the fact that said second volume (V2 ) houses a movable septum, arranged to slide within the second volume and is sealed around the perimeter with respect to the side walls de fining the second volume , wherein the movable septum is loaded by a resilient element ( SPR) , and by the fact that said crossing is forced against said movable septum, wherein the predetermined volume of water is such that a pressure value within the first volume is determined by a reaction force exerted by said movable septum .7 . A machine according to claim 6 , wherein said mechanical compression means are arranged to allow a backflow of liquid due to the return action of said movable septum .8 . A machine according to claim 7 , wherein said mechanical compression means are configured to cause at least one further crossing of liquid through said first volume aftersaid backflow.

9. A machine according to claim 7 or 8, wherein said mechanical compression means include a manual or electrically operated piston (P) , preferably comprising a vent valve designed to allow a preliminary expulsion of air before pressing said predetermined volume of water.

10. Machine according to claim 7 or 8, wherein said mechanical compression means includes a positive displacement pump and preferably means for preheating said second volume using recirculated hot water.

11. A machine according to any of claims 6-10, wherein said first and second volumes are formed by a separate body called the "capsule assembly" (GC) comprising- a tubular-shaped outer body (Cl) , configured to enclose the first and second volumes (VI, V2 ) , with a bottom wall defined by the first filter (FS1) ,- a tubular-shaped inner body (C2) , configured to enclose the second volume (V2) and equipped with a bottom wall defined by the second filter (FS2) and the movable septum (MS) loaded by the resilient element (SPR) and configured to be at least partially sealed into the outer body, wherein the inner body is cylindrical in shape and has a closed upper base and a lower base defined by the second filter (FS2) , the inner body is arranged to be sealed intothe outer body in a stable manner, and wherein the capsule assembly ( GC ) is configured to be stably inserted into the body (H) .

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