阅读说明：本技术 用于提高浓缩咖啡机中的浓缩咖啡浓度均匀性的方法以及相关的浓缩咖啡机 (Method for improving the espresso coffee consistency homogeneity in an espresso coffee machine and related espresso coffee machine ) 是由 S·德拉·皮特拉 R·加提 于 2019-06-07 设计创作，主要内容包括：本申请公开了一种用于制备和分配浓缩咖啡的机器,所述机器包括：咖啡锅炉；过滤器保持器,该过滤器保持器有用于压制咖啡粉圆盘的过滤器；预浸泡腔室；以及液压回路,用于从所述咖啡锅炉向预浸泡腔室输送增压水,其中,所述机器还包括用于检测表示所述预浸泡腔室和所述液压回路的填充的参数值的装置,因此,分配浓缩咖啡的步骤能够基于所述检测的填充参数值而开始。(The present application discloses a machine for preparing and dispensing espresso coffee, comprising: a coffee boiler; a filter holder having a filter for pressing a coffee powder disc; a pre-soak chamber; and a hydraulic circuit for delivering pressurized water from the coffee boiler to the pre-infusion chamber, wherein the machine further comprises means for detecting a parameter value representative of the filling of the pre-infusion chamber and the hydraulic circuit, so that the step of dispensing espresso coffee can be started on the basis of said detected filling parameter value.)

1. A machine (1000) for preparing and dispensing espresso coffee, comprising: a coffee boiler (1); a filter holder (8) having a filter (7) for pressing a disc of coffee powder; a pre-soak chamber (PC); and a hydraulic circuit (6, 9) for delivering pressurized water from the coffee boiler (1) to a pre-infusion chamber (PC), wherein the machine (1000) further comprises means (16, 24, 29) for detecting a change in a filling parameter (F, P, W) indicative of filling the pre-infusion chamber and the hydraulic circuit (6, 9), such that the step of dispensing espresso coffee can be started based on the detected change in the filling parameter (P, F, W) value.

2. The machine (1000) of claim 1, wherein: the means for detecting a change in a value representative of a filling parameter (F, P, W) filling the pre-soak chamber and the hydraulic circuit (6, 9) comprise a flow meter (16).

3. The machine (1000) of claim 1 or 2, wherein: the flow meter (16) is arranged to detect a slowing of the water flow, said slowing of the water flow being indicative of filling the pre-soaking chamber and the hydraulic circuit (6, 9).

4. The machine (1000) of any preceding claim, wherein: the means for detecting a change in a value indicative of a filling parameter (F, P, W) filling the pre-soak chamber and the hydraulic circuit (6, 9) comprises a pressure transducer (24).

5. The machine (1000) of claim 4, wherein: the pressure transducer (24) is arranged to detect a pressure difference of the water, said pressure difference of the water being indicative of filling the pre-soak chamber and the hydraulic circuit (6, 9).

6. The machine (1000) of any preceding claim, wherein: the means for detecting a change in a value representative of a filling parameter (F, P, W) filling the pre-infusion chamber and the hydraulic circuit (6, 9) comprise weighing means (29).

7. The machine (1000) of claim 6, wherein: the weighing means (29) are arranged to detect a weight or mass variation of the container for collecting the dispensed espresso coffee, wherein said weight or mass variation is indicative of the filling of the pre-infusion chamber and of the hydraulic circuit (6, 9).

8. A method for preparing espresso coffee by an espresso coffee machine, the coffee machine comprising: a coffee boiler (1); a filter holder (8) having a filter (7) for pressing a disc of coffee powder; a pre-soak chamber (PC); and a hydraulic circuit (6, 9) for delivering pressurized water from the coffee boiler (1) to a pre-infusion chamber (PC), the method comprising: -detecting a variation of a filling parameter (F, P, W) value representative of filling the pre-infusion chamber (PC) and the hydraulic circuit (6, 9), and-dispensing espresso coffee based on the detected variation of the filling parameter (P, F, W) value.

9. The method of claim 8, wherein: the change in the value of the filling parameter (F, P, W) comprises a change in at least one of: a parameter indicative of water flow, a parameter indicative of water pressure, and a parameter indicative of the weight or mass of the espresso coffee dispensed into the container.

10. The method of claim 9, wherein: the change in the value of the fill parameter (F, P, W) includes a slowing of water flow, a pressure differential, or a change in mass or weight.

Technical Field

The present invention generally relates to the field of espresso coffee machines. More particularly, the present invention relates to a method and a machine capable of dispensing espresso coffee with a desired strength.

Background

A number of machines for preparing beverages are known. In particular, a number of machines are known for preparing espresso coffee from coffee powder, pods, capsules or the like.

Generally, in machines for preparing espresso coffee, a flow of water at high pressure and temperature is made to pass through a disc of ground coffee. In some known machines, the pressure and/or temperature of the water passing through the coffee disc can be precisely adjusted. In some known machines, the pressure and/or temperature of the water can be varied during the dispensing process.

Some coffee machine manufacturers have adopted the above measures to improve the quality of the beverage by attempting to extract substances and flavors from the ground coffee powder more efficiently. The above-mentioned measures and others are also used to compensate for e.g. different coffee mixes, different processing operations, different particle sizes and different degrees of compaction of the ground coffee and different moisture percentages.

In some cases, coffee machine manufacturers also try to develop solutions that can be used to prepare coffee with the same characteristics.

Currently, machines for preparing espresso coffee, which dispense the beverage at a constant pressure, calculate the volume or mass of water for infusion (espresso coffee) from the moment the user gives a command to start infusion.

The same happens with machines having a control unit, in which the operator can select different pressure profiles. From the moment the operator commands, the machine starts to repeat the curve and to interrupt it after a predetermined volume of water or a predetermined mass of water has passed or once a certain total time has elapsed since the start of the infusion.

WO2011/140582 describes an improved method and apparatus for an espresso coffee machine. WO2011/140582 envisages a module for varying the power of a pump, which module is operatively connected to the pump. Preferably, the means for varying the pump power is able to determine a pressure curve for the flow delivered by the pump. In an embodiment, a module for varying the pump power may be used to obtain the pre-soak. According to one aspect of the subject matter of WO2011/140582, an espresso machine is provided comprising a module for varying the pump power for pre-infusion. In an embodiment, the module for varying the pump power may be used to determine a pressure profile in an espresso production cycle. The pressure profile may be preset or set by the user. More preferably, the pressure curve may take the form of a power-time curve representing the electrical power supplied to the respective pump. EP3225141 describes a coffee machine and a method of operation.

Disclosure of Invention

The applicant has perceived that it is not currently possible to obtain espresso coffee with a constant ratio with respect to the amount of solvent (water) and solute (ground coffee), at least because it is not possible to calculate precisely how much water is dispensed before the start of the pre-infusion.

In fact, in the case of variations in the quantity of ground coffee used by the user and/or in the fineness of grinding set by the user and/or in the pressure performed by the user, the volume of the empty space above the ground coffee disc varies. Thus, the amount of liquid dispensed to fill the empty space above the coffee powder disc varies before the pressurized hot water reaches the coffee powder disc.

In other words, one part of the feed water is used to fill the hydraulic circuit upstream of the filter holder, and the other part is used to fill the volume in the filter above the ground coffee disk. Although the volume of the hydraulic circuit can be calculated from information basically known to the espresso machine manufacturer, the volume above the coffee powder disk will vary as a function of the quantity of coffee powder used by the user and/or the fineness of grind set by the user and/or the pressure performed by the user. The volume may be from about 2.5cm³To about 10cm³. Obviously, such a water volume may significantly influence the strength of the obtained espresso coffee. For the same amount of water delivered, espresso will have a larger amount of available solvent when the volume upstream of the coffee disc is smaller, and a smaller amount when the volume upstream of the coffee disc is larger. In other words, for the same quantity of water supplied, when a smaller portion thereof is used to fill the coffee diskIn the free volume, the larger part will be used for the beverage; on the other hand, when a larger part of it is used to fill the volume upstream of the coffee disc, a smaller part will be used for the beverage. In practice, the strength of espresso coffee depends not only on the amount of water but also on the amount of powder.

As mentioned above, WO2011/140582 describes an improved method and apparatus for an espresso coffee machine. WO2011/140582 describes an espresso machine comprising a module for varying the power of the pump in order to provide pre-infusion. The module for varying the pump power can be used to determine the pressure profile during an espresso production cycle. According to WO2011/140582, the pressure curve can be preset or set by the user. The pressure curve may take the form of a power-time curve representing the electrical power supplied to the respective pump. The applicant has appreciated that this method is not entirely effective, since the preset pressure curve is a compromise and does not take into account the fact that the coffee disk is ground. For example, the preset curve does not take into account at least one of: the actual amount of ground coffee in the filter, the pressure of the ground coffee inside the filter, the average particle size of the ground coffee, and the water left in the circuit compared to the previous cycle. Similar considerations are valid for the pressure profile that can be set by the user, since the user may have a local and not completely precise knowledge of the amount of ground coffee in the filter and of the water left in the water circuit.

EP3225141 discloses a method for operating a coffee machine, in particular a coffee machine comprising a coffee grinder incorporated therein, which coffee grinder has an infusion chamber formed in an infusion cylinder, which infusion chamber is axially delimited by a piston movably arranged inside the infusion cylinder. The applicant has determined the object of providing an espresso coffee machine capable of producing espresso coffee with a set strength that is less dependent on the quantity of coffee powder used by the user and/or the fineness of grind set by the user and/or the pressure performed by the user.

According to the invention, the variation of the value of a parameter representative of the empty space upstream of the coffee powder-filled disc is detected. This filling parameter is taken into account for the subsequent pre-soaking step and the actual extraction step. In other words, according to the invention, the infusion step does not start from the moment when the pressurized hot water starts to flow from the coffee boiler, but from the moment when the circuit and the empty space upstream of the coffee powder disk are filled with water. The calculated concentration will not take into account the water used to fill the circuit and the empty space mentioned above.

The filling parameters may include changes in pressure, changes in flow, changes in mass, or any other combination of these parameters.

According to a first aspect, there is provided a machine for preparing and dispensing espresso coffee, the machine comprising: a coffee boiler; a filter holder having a filter for pressing a coffee powder disc; a pre-soak chamber; and a hydraulic circuit for delivering pressurized water from the coffee boiler to a pre-infusion chamber, wherein the machine further comprises means for detecting a change in a filling parameter value indicative of filling the pre-infusion chamber and the hydraulic circuit, such that the step of dispensing espresso coffee can be started based on the detected change in the filling parameter value.

According to an embodiment, the means for detecting a variation of a filling parameter value representative of filling the pre-soak chamber and the hydraulic circuit comprise a flow meter. For example, the flow meter is arranged to detect a slowing of the water flow. This slowing of the water flow is then representative of the filling of the pre-infusion chamber and of the hydraulic circuit. In fact, the flow of water towards the pressing coffee disc is free and substantially unimpeded until it comes into contact with the coffee disc, which creates resistance and slows down the flow of water.

According to other embodiments, the means for detecting a change in the value of a parameter representative of the filling of the pre-infusion chamber and of the hydraulic circuit comprise a pressure transducer. For example, a pressure transducer is provided to detect the pressure difference of the water. The pressure difference of the water is then representative of the filling of the pre-soak chamber and of the hydraulic circuit. In fact, as mentioned above, the flow of water towards the pressing coffee disc is free and substantially unimpeded until the water comes into contact with the coffee disc, which creates resistance and causes a pressure difference in the water.

According to other embodiments, the means for detecting the variation of the parameter values representative of the filling of the pre-infusion chamber and of the hydraulic circuit comprise weighing means. For example, the weighing device is arranged to detect a change in weight or mass of the container for collecting the dispensed espresso coffee. The weight of the container remains unchanged as long as espresso coffee does not flow into the container. When the beverage starts to flow into the capsule, the supplied water has filled the pre-infusion chamber and the hydraulic circuit and has wetted the coffee disc. Thus, the water dispensed before the espresso reaches the cup is the fill water and the brew ratio is calculated without consideration.

According to another aspect, the invention provides a method for preparing espresso coffee by means of an espresso coffee machine comprising: a coffee boiler; a filter holder having a filter for pressing a coffee powder disc; a pre-soak chamber; and a hydraulic circuit for delivering pressurized water from the coffee boiler to a pre-infusion chamber, the method comprising: detecting a change in a parameter value representative of the filling of the pre-infusion chamber and the hydraulic circuit, and dispensing espresso coffee based on the detected change in the filling parameter value.

The filling parameters may include a variation of at least one of: a parameter indicative of water flow, a parameter indicative of water pressure, and a parameter indicative of the weight or mass of the espresso coffee dispensed into the container.

The change in the filling parameter value may comprise a slowing of the water flow or a pressure difference or a change in mass or weight.

Drawings

The detailed description of the invention, which is provided by way of non-limiting example, will be read with reference to the accompanying drawings, in which:

FIG. 1 is an isometric view of one example of an espresso machine in which the present invention may be incorporated;

FIG. 2 is a first embodiment of a hydraulic circuit diagram of an espresso machine according to the present invention;

FIG. 3 is a second embodiment of a hydraulic circuit diagram of an espresso machine according to the present invention;

FIG. 4 is a cross-sectional view through the coffee boiler and filter holder without water;

fig. 5 shows the same components as in fig. 4, wherein a first quantity of water in the circuit is directed towards the ground coffee disc;

fig. 6 shows the same components as in fig. 4, wherein the water completely fills the circuit and all the space above the coffee disc.

FIGS. 7-9 are three different flow diagrams of three variations of the method according to the invention; and

fig. 10 shows the connection between the detection means and the processing means.

Detailed Description

Fig. 1 shows, by way of example only, an espresso machine, generally designated by reference numeral 1000. The machine 1000 comprises a substantially closed machine body 1001, which machine body 1001 houses the main components of the machine, some of which will be described later. Preferably, the machine 1000 includes a surface 1002 at the top, and the cup can be placed on the surface 1002. A resistor (not shown) or other heating system for heating the cup on surface 1002 may also be provided.

The machine 1000 comprises at least one dispensing group 1003 for dispensing espresso coffee. Preferably, the machine 1000 comprises a plurality of allocation groups 1003, for example three groups, similar to the machine represented by way of example in fig. 1. There may also be two, four or more allocation groups. A drip tray 1004 is preferably present below the dispensing group 1003, which drip tray 1004 is preferably partially enclosed on top by a grid 1005. Typically, during the process of dispensing espresso, a coffee cup is placed on the grid 1005.

A filter holder supporting a filter for the coffee powder disk may be detachably connected to each dispensing group 1003.

The machine 1000 may include one or more displays 1010 and buttons, for example, for turning the machine on/off and/or for starting/ending a dispense.

For each dispensing group 1003, the machine 1000 shown in fig. 1 further comprises a lever 1112 for starting/ending the dispensing of espresso and/or for varying the dispensing pressure during the dispensing of espresso.

Before describing in detail the hydraulic diagram shown in fig. 2 and 3, a number of reference numerals will be used and a brief description of the individual components will be presented below.

1 coffee boiler

10 Pump

11 expansion valve

12 check valve

13 preheater mixing valve

14 steam boiler

15 pressure reducing valve

16 flow meter (volumetric flow meter)

18 ball cock

19 steam electrovalve

20 steam stick

21 hot water mixing valve

22 steam boiler filling electrovalve

23 Hot water rod

24 pressure transducer

25 steam boiler pressure gauge

26 drainage well

27 gear pump

28 safety valve

29 weighing system

In fig. 2 and 3, the following notation system is used: the cold water flow is indicated by "long dash-single short dash-long dash"; the hot water flow is indicated by a solid line, the vapor flow by a dashed line, and finally the effluent water flow is indicated by "long dashed line-short double dashed line-long dashed line".

Briefly, in the example diagram shown in fig. 2, cold water from a mains pipe (or from any other source) is supplied to the pump 10. The pump 10 supplies water to a steam boiler 14, the water preferably passing through a check valve 12 and a preheater mixing valve 13.

Preferably, a steam wand 20 is connected to the steam boiler 14 in order to dispense steam and, for example, to froth milk for preparing cappuccinos.

Preferably, the steam boiler 14 is in fluid communication with a hot water wand 23 for supplying hot water for preparing infusions (e.g. tea or soups).

As shown in fig. 4, the water coming from the coffee boiler 1 is conveyed to the distribution group 1003 through the infusion electrovalve 9 and the infusion water pipe 6. In particular, the water coming from the pipe 6 preferably reaches the shower sieve 4, through which shower sieve 4 the water is substantially uniformly distributed on the ground coffee disk housed inside the filter 7 supported by the filter holder 8. The ground coffee disk comprises ground coffee that is pressed by the attendant before the filter holder engages the bottom part of the dispensing group 1003.

Preferably, the infusion electrovalve 9 is a three-way valve. The infusion electrovalve 9 comprises a first passage for extracting the infusion water from the coffee boiler 1, a second passage connected to the infusion water supply pipe 6 and a third passage for connecting the infusion area to the discharge outlet.

The steepwater supply conduit 6 is preferably in fluid communication with the diffuser screw 3 and the shower screen 4.

During use, when a user wishes to prepare espresso, he/she presses a button (or starts the extraction process in some other way). The infusion water is drawn through the outlet pipe of the infusion electrovalve 9 of the coffee boiler 1 and is directed towards the coffee disc through the infusion water supply pipe 6. The pressurized water begins to flow into the steepwater supply conduit 6 (figure 5) until it is completely full. The pressurized hot water then flows into the empty space above the coffee disk.

In the present description and claims, the expression "free space above the coffee powder disc" (or similar expressions) is understood to mean a space (or volume) which is not filled with water before the preparation of espresso coffee is started. The space or volume is delimited at the bottom by a coffee powder disc and at the top by a coffee boiler. Typically, this empty space comprises a pre-infusion chamber, an infusion electrovalve and a tube for supplying infusion water. The term "pre-infusion chamber" should be understood to mean a chamber delimited at the bottom by the upper surface of the coffee disc, at the side by the upper portion of the side wall of the filter containing the coffee disc, and at the top by the bottom surface of the dispensing group. In the following, this empty space will be indicated by the letter "V".

The espresso coffee machine according to the invention is capable of estimating directly or indirectly the volume of the free space above the coffee disc and not used for infusion.

The main purpose of the machine according to the invention is to ensure repeatability and uniformity of the quantity of water passing through the coffee disc during the infusion preparation. In order to be able to obtain this result, the quantity of water to be used to fill the empty space upstream of the coffee disc must be determined before starting the extraction step. The machine according to the invention is arranged to determine, for each coffee infusion, the quantity of water passing through the disc, so as to estimate how much of the total dispensed water will be used to fill the empty space,

according to a first embodiment, the machine comprises a positive displacement flow meter (flowmeter) 16 (fig. 10a) connected to a control unit (CPU)60 of the machine 1000. Preferably, a flow meter 16 is arranged immediately downstream of the soaking electrovalve 9. Alternatively, the flow meter 16 may be arranged at another position further downstream or further upstream of the soaking electro-valve 9. The connection between the flow meter 16 and the control and/or processing unit 60 may be made by cable or wirelessly.

According to the invention, the slowing of the flow detected by the flow meter 16 indicates the filling of the empty space V above the coffee disc. In other words, when the user starts to dispense a dose of espresso coffee, the pressurized water starts to flow freely inside the infusion water supply duct 6 until the empty space V above the coffee disc is filled. Once the entire volume V is filled, the pressurized water flow slows down because it meets the resistance of the coffee disk. This resistance is detected by the flow meter 16, typically due to the flow meter 16 suddenly reducing its rotational speed.

By determining the time at which the slowing down takes place, it is possible to calculate the quantity of water used to fill the empty space V above the coffee disc and to start calculating the actual quantity of water used for infusion and thus determine the end time of the pre-infusion step.

According to a second embodiment, the machine comprises a pressure transducer 24 connected to a control unit (CPU)60 of the machine. Preferably, the pressure transducer 24 is arranged in the vicinity of the distribution group, in fluid communication with the coffee boiler (fig. 3 and 10 b). It may also be in the same location as the flow meter 24. The connection between the pressure transducer 24 and the control and/or processing unit 60 may be made by means of cables or wirelessly.

According to the invention, the increase in pressure detected by the pressure transducer 24 is indicative of filling the empty space above the coffee disc and in the infusion water supply tube 6. In other words, when the user starts to dispense a dose of espresso coffee, the pressurized hot water starts to flow freely inside the infusion water supply pipe 6 until the empty space V above the coffee disc is filled. Once the entire volume is filled, the pressure inside the empty space above the coffee disc increases until the dispensing value. The pressurized water then begins to pass through the coffee disk and the pressure detected by the pressure transducer 16 is the dispensing pressure generated by the pump 10. The dispensing pressure value may be set as a variable pressure curve in the dispensing process.

By determining the moment when the pressure increase occurs, it is possible to calculate the amount of water used to fill the tube above the coffee disc and to start calculating the amount of water used for infusion, thus determining the end of the pre-infusion step.

According to a third embodiment, the machine 1000 comprises means 29 (fig. 3) for detecting a variation in the weight or mass of the beverage inside the cup (or other container) located below the dispensing group 1003 of the espresso coffee machine 1000. The change in weight or mass of the beverage inside the cup indicates the empty space above the filled ground coffee disc. In other words, when the user starts to dispense a dose of espresso coffee, the pressurized hot water starts to flow freely inside the infusion water supply tube 6 until the empty space V above the coffee disc is filled. Once all of these volumes are filled, the pressurized water begins to pass through the ground coffee disk and fall into the cup below the dispensing group. The moment when the weight or mass changes is the moment when the machine is able to determine the quantity of water used for soaking and therefore the end of the pre-soaking step.

The weighing unit 29 is preferably connected to the control and/or processing unit 60 by means of a cable or wirelessly.

It is clear that two or more of the above-described embodiments can be combined in order to ensure a higher accuracy in determining the empty space above the coffee disc to be filled and thus the start of the flow of pressurized water for the actual extraction process.

For example, according to another embodiment, a pressure transducer associated with the flow meter may be provided. When two or more devices representing filling are combined, the control unit of the machine is programmed to manage these two values (in this case the pressure and flow values) and to determine a single filling end moment (pre-soak end and start dispensing).

According to an embodiment, the parameter value representing the filling of the free space above the coffee disc may be used for an ongoing dispensing operation and/or for a subsequent dispensing operation using a self-learning mechanism in order to improve the detection accuracy and/or speed.

Fig. 7, 8 and 9 show three different flow charts regarding the method according to the three main embodiments.

The flow chart in fig. 7 relates to a first embodiment, wherein the parameter representing filling of the empty space above the coffee disc is a flow parameter.

The method envisages monitoring (101) the flow value, for example by means of a flow meter 16 or the like, after starting (100) the dispensing of espresso coffee (single cup, double cup, etc.). This is followed by detecting (202) that the flow is slowed down or that the flow value is below a predetermined threshold, which is considered to indicate that the empty space above the coffee powder disc has been completely filled. From the moment it is determined that the empty space above the ground coffee disc is completely filled, pressurized water is dispensed by a predetermined amount and/or for a predetermined time (104) in order to obtain the desired amount of espresso coffee in the cup. The pressure of the hot water dispensed before the moment indicating the filling of the empty space may be lower than the pressure after the moment. The amount of espresso coffee required in the cup may depend on the amount of powder used in order to obtain the desired brewing ratio (dilution ratio between water and coffee powder), or on other requirements, such as weight and/or volume.

The flow chart in fig. 8 relates to a second embodiment, wherein the parameter representing filling of the empty space above the coffee disc is a pressure parameter.

The method envisages monitoring (201) the pressure value after starting (200) the dispensing of espresso coffee (single cup, double cup, etc.), for example by means of the pressure transducer 24, etc. This is followed by the detection (202) of a dispensing pressure value or, in any case, a value higher than a predetermined threshold, which is considered to indicate (203) that the empty space above the coffee powder disc has been completely filled. From the moment it is determined that the empty space above the ground coffee disc is completely filled, pressurized water is dispensed by a predetermined amount and/or for a predetermined time (204) in order to obtain the desired amount of espresso coffee in the cup. The pressure of the hot water dispensed before the moment of indicating the filling of the empty space may be lower than the pressure after this moment. The amount of espresso coffee required in the cup may depend on the amount of powder used in order to obtain the desired brewing ratio (dilution ratio between water and coffee powder), or on other requirements, such as weight and/or volume.

The flow chart in fig. 9 relates to a third embodiment, wherein the parameter representing filling of the empty space above the coffee disc is a weight or mass parameter.

The method envisages that after starting (300) the dispensing of espresso coffee (single cup, double cup, etc.), the mass or weight value of the container in which the beverage is to be collected is monitored (301). For example, a weighing device 29 can be used. A mass or weight value greater than the mass or weight (tare) of the empty container is then detected (302). This value is considered to indicate that the empty space above the ground coffee disc has been completely filled and that a portion of the beverage has started to collect inside the receptacle (cup). From the moment it is determined that the empty space above the ground coffee disc is completely filled, pressurized water is dispensed by a predetermined amount and/or for a predetermined time (304) in order to obtain the desired amount of espresso coffee in the cup. The pressure of the hot water dispensed before the moment indicating the filling of the empty space may be lower than the pressure after the moment. The amount of espresso coffee required in the cup may depend on the amount of powder used in order to obtain the desired brewing ratio (dilution ratio between water and coffee powder), or on other requirements, such as weight and/or volume.