Portafilter basket

Abstract

Portafilter basket (1) for coffee extraction, comprising a basket bottom (10) to be positioned in a portafilter for supporting ground coffee during extraction, wherein the basket bottom comprises an upper surface (2) provided with upper openings (20); a lower surface (3) provided with lower openings (30); and channels (4) that fluidly connect the upper openings with respective lower openings and thereby allow extracted coffee (93) to flow through the basket bottom (10), characterised in that at least one of the channels (4) is arranged such that a horizontal position of the cross section of the channel is varied between the respective upper opening (20) and lower opening (30).

Description

[0001] Title: PORTAFILTER BASKET

[0002] FIELD OF THE INVENTION

[0003] The present disclosure relates to a portafilter basket for a coffee machine, a portafilter provided with the portafilter basket and to a method for manufacturing a portafilter basket.

[0004] BACKGROUND OF THE INVENTION

[0005] The enormous popularity of coffee throughout the world has led to an explosion of efforts to optimize each and every step in the coffee making process. The aim is the perfect cup of coffee.

[0006] Referring to Figure 1 and 3B, typically, extracting a cup of espresso includes the steps of grinding roasted coffee beans; filling a filter device 1 , typically a basket 1 included in a portafilter holder 91 , with a certain amount of ground coffee 95. The coffee in the portafilter basket 1 is compressed into what can be referred to as a puck; and pressurized hot water is led though the puck of compressed coffee in the portafilter basket, extracting a stream of coffee 93, 94 from the puck.

[0007] A naked portafilter holder 9, as shown in Figures 1 and 2, has a basket holding ring 91 with an open bottom such that the bottom 10 of the basket 1 is visible. The naked portafilter can be used to review the quality of the coffee extraction. Figure 1 shows an example of very good extraction. Herein, the stream of extracted coffee 93 coming out of the bottom of the filter basket 1 is focused. Figure 2 shows an example wherein a stream 94 of extracted coffee is suboptimal.

[0008] The suboptimal stream 94 shown in Figure 2 provides an example wherein the coffee extraction is messy, indicating that extraction issues are happening inside the filter basket 1. Typically, the latter include so-called channeling. The extraction issues ultimately lead to not only a messy counter, but to a poorly extracted shot of espresso as well.

[0009] Channeling herein relates to the channels in the coffee puck. Water will follow the path of least resistance, and this is particularly true when water is under pressure, such as during coffee extraction. If the coffee puck in the basket has an uneven consistency, water will not flow uniformly through the coffee grounds. This may for example occur when the coffee is unevenly ground, improperly distributed and / or tamped. Channeling may be defined as when the extracted coffee finds a specific narrow path through the bed of coffee instead of flowing through the entire bed evenly. This leads to why channeling is so bad, it ruins the clarity of flavor of the espresso. The more evenly the coffee grounds are distributed in the filter basket and retained as a consistent puck during extraction, the less likely it is to see instances of channeling. Channeling inside the coffee grounds in the filter may typically lead to spurting, which is visible in the form of streams or jets of liquid spraying from the filter basket. See Figures 2 and 3C for an example. After brewing, it may be possible to observe holes or cracks 96 in the spent coffee grounds, which can be a sign that channeling has occurred.

[0010] Not only is channeling messy, but it also indicates that the coffee grounds are extracted unevenly. The areas of higher flow, i.e. in the channels, will tend to be over extracted, while the rest of the coffee grounds will tend to be under extracted. This leads to, for instance, improper flavors and an unbalanced espresso.

[0011] Conventionally, portafilter baskets are manufactured by stamping and punching of sheet metal. However, it has been found that the basket may deform unevenly during use as the result of a relatively large extraction pressure of around 9 bars. The basket bottom 10 may bulge outwardly, as depicted in Fig. 3C, and / or a side wall 11 of the basket may acquire an oval shape. This introduces multiple problems:

[0012] First, as a result of the deformation, the compressed coffee puck 95 may be improperly supported by the basket bottom during extraction and / or be compressed by the side walls of the basket. This can cause fracture lines in the coffee puck and may even lead to the puck breaking into separate pieces as in Fig. 3C. As a result, consistency of the puck is reduced and channeling may occur.

[0013] Secondly, before providing pressurized water for coffee extraction, the ground coffee is usually distributed over the basket and / or tamped. These steps are often performed using tools that are designed for a circular shape of the basket in order to function optimally. When the basket deviates from the circular shape, e.g. due to deformation of the side walls 11 and / or bottom wall 10, such as acquires an oval shape, the tools may not function properly and the ground coffee may be distributed or tamped unevenly. When deformation is severe, tools may even not fit on / within the basket.

[0014] Another problem is that the minimum size of the openings in the basket bottom 10 as a result of the manufacturing by punching / stamping cannot be less than 0.3 mm.

[0015] Similarly, limitations are imposed on the distance between respective openings, whereas for different coffee types and / or recipes smaller opening sizes and / or distances may be desired.

[0016] Further, the flow of extracted coffee outside of the portafilter and the cup may be relatively uncontrolled, especially in combination with channeling, as explained above.

[0017] Therewith, a stream of extracted coffee may randomly converge into a single stream relatively fast or slow. This will influence the amounts of foam and extracted coffee that reach a cup underneath, as well as the amount of oxygen that comes into contact with the extracted coffee.

[0018] Controllability of the flow may further improve coffee taste, consistency and esthetics. OBJECT OF THE INVENTION

[0019] The present disclosure aims to provide an improved portafilter basket, such as a portafilter basket that provides an improved taste and / or esthetics, is less prone to deformation and / or channeling, or at least to provide an alternative portafilter basket, for example a basket having a better controlled and / or more consistent outflow.

[0020] SUMMARY OF THE INVENTION

[0021] Aspects of the present invention are set out in the accompanying claims. The disclosure provides a portafilter basket for coffee extraction according to claim 1. The portafilter basket comprises a basket bottom to be positioned in a portafilter for supporting ground coffee during extraction.

[0022] The basket bottom comprises an upper surface provided with upper openings; a lower surface provided with lower openings; and channels that fluidly connect the upper openings with respective lower openings and thereby allow extracted coffee to flow through the basket bottom.

[0023] At least one of the channels is arranged such that a horizontal position and / or a size of the cross section of the channel is varied between the respective upper opening and lower opening. The horizontal position of the upper opening may be defined by the location of the centre of the upper opening in the upper surface and the horizontal position of the lower opening may be defined as the location of the centre of the lower opening in the lower surface. The horizontal position of the respective upper opening and lower opening may be varied such that the upper opening and the lower opening do not completely overlap, e.g. the upper opening and the lower opening may partially overlap, for example in a direction perpendicular to a thickness of the basket bottom, e.g. when seen from the lower surface and / or upper surface. For example, a size of the upper opening may be different from the lower opening wherein the upper opening and the lower opening are not coaxially aligned with each other, e.g. the side wall of the respective channel, extending between the lower opening and the upper opening, may be partially skewed.

[0024] In addition or as an alternative, a size and / or a shape of the cross section of the channel is varied, for example such that a hydraulic size experienced by the flow of extracted coffee is varied between the respective upper opening and lower opening. By varying the horizontal position of the cross section over the length of the channel, the stream of extracted coffee will, in addition to a vertical flow speed as in the prior art, acquire a horizontal flow speed. Therewith, the exiting direction of the stream of extracted coffee can be steered and several advantages can be provided: Firstly, due to the horizontal flow speed, the outflow direction of the stream of extracted coffee will be less random compared to a vertical outflow direction, such that the outflow direction may be predicted better.

[0025] Secondly, the outflow may converge into a focused bundle earlier. Therewith, sputtering may be reduced and the amount of extracted coffee reaching the cup, as well as oxygen contact and / or coffee taste may be more constant with each cup of coffee.

[0026] Further, the horizontal flow speed will normally reduce a vertical flow speed component of the water through the channel. As such, the risk of channelling in the puck due to high vertical flow speeds may be reduced.

[0027] Finally, the horizontal flow speed of the stream of extracted coffee, in particular when converging into a focused stream, is often perceived as aesthetically pleasing. This aesthetic effect is especially advantageous in so-called naked portafilter holders wherein the stream of extracted coffee is relatively well visible.

[0028] Therewith, the present invention may provide an improved portafilter basket, resulting in an improved taste and esthetics, is less prone to deformation and / or channeling at a potentially better controlled outflow.

[0029] A centre of the upper opening in the upper surface may be offset from a centre of the respective lower opening in the lower surface. Multiple channels may be arranged such that their respective upper openings are offset from their respective lower openings, for example all channels may have offset upper openings and lower openings.

[0030] The respective centres of respective upper openings and lower openings may be offset in a direction substantially parallel to the upper surface and / or the lower surface.

[0031] In an embodiment, the upper opening and the respective lower opening of the at least one channel are horizontally offset from each other. For example, the horizontal offset may be such that when the portafilter basket is in use, i.e. during extraction of coffee, the stream of extracted coffee through the respective at least one channel will acquire a horizontal flow speed.

[0032] A longitudinal axis of a channel may be defined by an axis through the centre of the upper opening in the upper surface and through the centre of the lower opening in the lower surface. The respective upper opening and the respective lower opening of the respective channel may be horizontally offset such that a longitudinal axis of the channel is skewed. This way, the extracted coffee may be provided with a horizontal flow speed component. The horizontal flow speed may be such that an outflow direction of extracted coffee out of the at least one channel can be predetermined. The longitudinal axis may be skewed with respect to the basket bottom, e.g. with respect to a horizontal when the portafilter basket is in use, i.e. when arranged in a portafilter during extraction. In an embodiment, upper openings and the respective lower openings of multiple channels are horizontally offset from each other. By having multiple skewed channels, the outflow out of the multiple skewed channels may be provided with a horizontal flow speed component, such that an overall flow speed may be influenced.

[0033] In particular, the longitudinal axes of the respective channels may be non-parallel to each other. This way, the flow speed direction of the extracted coffee may be influenced depending on the location of the respective channel in the portafilter. E.g., channels may be provided with a skew that varies with a distance from the centre of the portafilter, such that the horizontal flow speed of extracted coffee is varied accordingly. This way, flow speeds through the coffee puck may be influenced to improve uniformity of coffee extraction.

[0034] In an embodiment, the channels are arranged at such angles with respect to each other that the respective longitudinal axes converge towards each other and thereby define a focal point in which the longitudinal axes intersect. This way, the flow of extracted coffee underneath the filter basket may converge into a focused bundle earlier compared to a conventional portafilter basket.

[0035] As such, the filter basket may be configured to provide for a focused outflow of extracted coffee and can be referred to as a focus-flow filter basket. Therewith, sputtering may be reduced and the amount of extracted coffee reaching the cup, as well as oxygen contact and / or coffee taste may be more constant with each cup of coffee.

[0036] In an embodiment, a distance between the lower surface and the defined focal point is less than 120 mm, such as 20 -100 mm, e.g. 50-70 mm.

[0037] It has been found that these distances provide for an advantageous combination of improved taste and esthetics.

[0038] In an embodiment, a thickness of the basket bottom is varied over the upper surface, for example such that the length of the channels is dependent on the location of the channels in the basket bottom. By varying thickness over the upper surface it is meant that over the thickness of the basket bottom is dependent on position, i.e, the thickness of the basket bottom, in use, may be variable in a horizontal plane. A height of the upper surface and / or a height of the lower surface of the basket bottom may be varied over the respective surface.

[0039] By having a variable thickness, the flow resistance in the channel and the associated pressure drop may be predetermined and / or adapted depending on the location in the basket bottom.

[0040] In an embodiment, a thickness of the portafilter basket is varied. For example, a bottom wall, side wall, bottom wall, support surface and / or another portion of the portafilter basket may be provided with a variable thickness. This way, the portafilter basket may be configured to absorb relatively high stresses at locations that are subject to such stresses, for example near the basket bottom and / or at support surfaces. As such, form stability and / or durability of the portafilter basket may be improved.

[0041] In an embodiment, the channels are defined in the basket bottom by outer walls that are at least partially arranged at a non-perpendicular angle with respect to the upper surface and / or to the lower surface. For example, channel walls may be provided with a funnel shape.

[0042] This way, friction experienced by the flow of extracted coffee when entering and / or leaving the channel, as well as associated flow speeds of extracted coffee may be further adapted locally.

[0043] Although individual lower openings and / or upper openings may be provided with varying surface areas, a total opening surface area of the lower openings may be the same as a total opening surface area of the upper openings.

[0044] In an embodiment, an upper opening surface area of the upper openings and a lower opening surface area of the lower openings differ from each other. It has been found that a different opening surface area may allow for a more gradual pressure gradient in the flow of extracted coffee, which may contribute to improved taste and / or aesthetics.

[0045] In an embodiment, the upper opening surface area is smaller than the lower opening surface area. As the pressure in the portafilter, when extracting coffee, is usually higher than an ambient pressure, a smaller upper opening surface area allows for a gradual decrease in pressure experienced by the extracted coffee.

[0046] In an embodiment, at least one of the channels has a diameter of less than 0.3 mm, for example less than 0.2 mm, such as less than 0.1. It has been found that a relatively small diameter may further improve taste and / or aesthetics of the extracted coffee, for example by providing an improved crema.

[0047] In an embodiment, a cross-sectional shape of the upper openings and a cross-sectional shape of the lower openings differ from each other.

[0048] The shape of the openings may influence the flow through the channels. The shape may e.g. be circular, oval, polygonal, e.g. rectangular, or any other desired shape.

[0049] The invention further relates to a portafilter provided with a portafilter basket according to any of the embodiments disclosed herein. The invention further relates to a coffee machine provided with the portafilter according to any of the embodiments disclosed herein.

[0050] Various embodiments of the portafilter basket as disclosed herein may be provided in the portafilter and / or in the coffee machine and thereby provide similar advantages.

[0051] According to another aspect, the disclosure provides a method for manufacturing a portafilter basket, e.g. according to any of the embodiments disclosed herein, using metal injection moulding, comprising the steps of providing a metallic basket material; and shaping the metallic basket material into a portafilter basket by means of metal injection moulding.

[0052] It has been found that the use of metal injection moulding allows for a wider range of positions, sizes and / or shapes of portafilters, in particular of the channels thereof, compared to the prior art.

[0053] Metal injection moulding technology may also provide advantages for manufacturing a portafilter basket not according to the present disclosure.

[0054] Further, various aspects and features of the portafilter basket described in the application can be applied in portafilters and / or methods for manufacturing a portafilter basket, which are not according to the present invention. These aspects or features, for example, the method for manufacturing a portafilter basket using metal injection moulding, can be made subject of divisional patent applications.

[0055] In an embodiment of the method, the step of shaping the metallic basket material comprises forming a basket bottom having at least one channel that is arranged such that a horizontal position and / or a size of the cross section of the channel is varied between the respective upper opening and lower opening of the channel. In addition or as an alternative, a shape of the cross section is varied, such that a hydraulic size experienced by the flow of extracted coffee is varied between the respective upper opening and lower opening, e.g. wherein the size and / or position of the cross section remains constant.

[0056] In an embodiment, the method is performed to manufacture a portafilter basket according to any of the embodiments disclosed herein. Thereby, similar advantages may be achieved as described for the portafilter basket.

[0057] According to another aspect, the disclosure provides a use of a portafilter basket, a portafilter and / or a coffee machine according to any of the embodiments disclosed herein, comprising the steps of: providing the portafilter basket arranged in a portafilter; arranging ground coffee in the portafilter basket; and extracting coffee by allowing a fluid to flow through the ground coffee.

[0058] BRIEF DESCRIPTION OF THE DRAWINGS

[0059] Reference will be made to the figures on the accompanying drawings. The figures are schematic in nature and may not necessarily be drawn to scale. Similar reference numerals denote similar parts or parts having a corresponding function. On the attached drawing sheets:

[0060] Figure 1 shows a perspective view of a bottomless portafilter and filter basket, exemplifying optimal coffee extraction; Figure 2 shows a perspective view of a bottomless portafilter and filter basket, exemplifying sub-optimal coffee extraction;

[0061] Figure 3A schematically shows a top view of a naked portafilter holder;

[0062] Figure 3B schematically shows a cross section of a filter basket exemplifying optimal coffee extraction;

[0063] Figure 3C schematically shows a cross section of a deformed prior art filter basket exemplifying sub-optimal coffee extraction;

[0064] Figure 4A schematically shows a top view of a portafilter basket according to an embodiment;

[0065] Figure 4B schematically shows a side view of the portafilter basket according to Fig. 4A;

[0066] Figure 4C schematically shows a cross section of the portafilter basket of Fig 4A along line (A-A);

[0067] Figure 5A schematically shows a side view of a cross section of a portafilter basket bottom according to an embodiment;

[0068] Figure 5B schematically shows a side view of a cross section of a portafilter basket bottom according to another embodiment;

[0069] Figure 5C schematically shows a side view of a cross section of a portafilter basket bottom according to another embodiment;

[0070] Figure 5D schematically shows a side view of a cross section of a portafilter basket bottom according to another embodiment;

[0071] Figure 6A schematically shows a cross section of a portafilter basket according to an embodiment; and

[0072] Figure 6B schematically shows a cross section of a portafilter basket according to another embodiment.

[0073] DETAILED DESCRIPTION

[0074] The invention will be further elucidated in exemplary embodiments thereof as described below.

[0075] Generally referring to Figure 3A, a naked portafilter holder 9 generally comprises a handle part 90, a basket holding part 91, and mounting cams 92 for mounting the portafilter holder 9 in a coffee machine. The basket holding part 91 may be provided with a portafilter basket 1 , as described in different embodiments herein.

[0076] An example of a portafilter basket 1 is provided in Fig 3B. The basket 1 has a bottom wall 10 a side wall 11 and a support surface 12 that is arrangeable on the basket holding part. The bottom 10 is provided with channels 4 that are for example stamped therein. As a result, the channels extend such that their respective longitudinal axes L are perpendicular to the bottom 10. When provided in the coffee machine, the channels 4 generally extend vertically through the bottom 10. When pressure is provided, deformations may result in basket T of Fig. 3C, wherein a crack 96 is caused in the coffee 95. Side wall 11 is bent and, due to deformation of bottom 10, longitudinal axes L’ of the channels 4 extend away from each other, thereby counteracting focusing of the coffee stream 94.

[0077] The filter basket 1 shown in Figs. 4A-4C comprises a basket bottom 10 to be positioned in a portafilter for supporting ground coffee during extraction. The basket bottom comprises an upper surface 2 provided with upper openings 20, a lower surface 3 provided with lower openings 30 and channels 4 that fluidly connect the upper openings with respective lower openings and thereby allow extracted coffee 93 to flow through the basket bottom 10. Not that not all upper openings 20, lower openings 30 and respective channels 4 are provided with a reference number in the figures.

[0078] At least one of the channels 4 is, in this embodiment all channels except for centre channel 4’ are, arranged such that a horizontal position and / or a size of the cross section of the channel is varied between the respective upper opening 20 and lower opening 30. In this embodiment, both the size and the horizontal position are varied, however, only size may be varied whereas position remains constant over the length of the channel, or vice versa.

[0079] The upper opening 20 and the respective lower opening 30 of each of the at least one channel 4 are horizontally offset from each other. In other words, the centre of the upper opening 20 and the lower opening 30 are offset from each other in a direction perpendicular to the thickness t of the bottom 10.

[0080] The horizontal position of the upper openings 20 and respective lower openings 30 (except for the upper opening 20’ and lower opening 30’ of the centre channel 4’) is varied such that the respective upper openings 20 and lower openings 30 do not completely overlap, e.g. they partially overlap in a direction perpendicular to a thickness of the basket bottom, e.g. when seen from the lower surface 2 and / or upper surface 3. In particular, a size of the upper openings 20 is different from a size of the respective lower openings 30, and the upper openings 20 and lower openings 30 are not coaxially aligned with each other, e.g. the side walls of respective channels, extending between the respective lower opening and the respective upper opening, are partially skewed.

[0081] A longitudinal axis L of the channel 4 through the respective centre points of the openings is skewed, except for the longitudinal axis L through the upper opening 20’ and lower opening 30’ of the centre channel 4’ located in the centre of the basket.

[0082] The upper openings 20 and the respective lower openings 30 of multiple channels are horizontally offset from each other and the longitudinal axes L of the respective channels 4 are non-parallel with each other.

[0083] Each longitudinal axes defines an angle a with the basket bottom 10. The angle a, in this embodiment, varies with the distance between the channel 4 and the centre channel 4’. In particular, the channels 4 are arranged at such angles with respect to each other that the respective longitudinal axes L converge towards each other and thereby define a focal point F in which the longitudinal axes L intersect.

[0084] A distance d between the lower surface 3 and the defined focal point F is less than 120 mm, such as 20 -100 mm, e.g. 50-70 mm. Other distances may also be provided.

[0085] In Fig. 4C, the bottom 10 is shown having a constant thickness t. Generally referring to Fig 5A, the thickness t of the basket bottom 10 may also be varied over the upper surface 2. The length of the channels 4 may be varied such that the length is dependent on the location of the channels in the basket bottom. This way, flow resistance in channels 4 may be altered. For example, channels 4 having a larger skew a may have a larger flow resistance than channels 4 having a smaller skew a, such as centre channel 4’ in this embodiment. Additionally, channels 4 located towards the outer circumference of the portafilter basket 1, i.e. at a larger distance from the centre channel 4’ may be located at a larger distance from a coffee machine outlet. By varying the thickness t of the bottom, the flow may be divided over the channels more equally.

[0086] Generally referring to Fig. 5B, in addition to or alternatively to varying the length of the channels 4, the width of the respective channels 4 may be varied, for example in dependence of skew a and / or distance to the centre of the basket 1.

[0087] Further, any combination between the horizontal position offset of the upper opening 20 and lower opening 30 may be made, as well as in sizes of the openings, skews in the channels, lengths of the channels and widths of the channels, as shown in Fig. 5C and 5D.

[0088] For example, the channels may be defined in the basket bottom by outer walls 40 that extend between the upper opening 20 and lower opening 30. In an embodiment, one upper opening may be fluidly connected to multiple lower openings, or vice versa.

[0089] In some embodiments, as shown in Fig. 5C and 5D, the outer walls 40 are at least partially arranged at a non-perpendicular angle with respect to the upper surface 2 and / or to the lower surface 3. It has been found that this way, the flow of water into and / or out of the channel may be less turbulent.

[0090] In Fig 5A and 5B, a surface area of the upper openings 20 is equal to a surface area of the lower openings 30. In other embodiments, an upper opening surface area of the upper openings 20 and a lower opening surface area of the lower openings 30 differ from each other. At least one of the channels may have a diameter smaller than 0.3 mm, such as less than 0.2 mm, in particular less than 0.1 mm.

[0091] In Fig. 4G, the upper opening surface area is smaller than the lower opening surface area. In other embodiments, the upper opening surface area may be larger than the lower opening surface area. Also, individual opening sizes may be varied such that some of the upper openings are larger than some of the lower openings, whereas the upper opening surface area is still smaller than the lower opening surface area, or vice versa.

[0092] Although both the upper openings 20 and the lower openings 30 may be circular, a cross- sectional shape of the upper openings and a cross-sectional shape of the lower openings may also differ from each other. Openings may for example be polygonal. Further, the shape of some of the openings on the upper and / or lower surface may differ from other openings on the same surface.

[0093] As indicated in Figs 5A-5D, a centre 21 of the upper opening 20 in the upper surface 2 is offset from a centre 31 of the respective lower opening 30 in the lower surface 3. Multiple channels 4 are arranged such that their respective upper openings 20 are offset from their respective lower openings 20 in a direction substantially parallel to the upper surface 2 and lower surface 3, in particular in horizontal direction, such that when the portafilter basket is in use, i.e. during extraction of coffee, the stream of extracted coffee through the respective at least one channel 4 will acquire a horizontal flow speed.

[0094] A longitudinal axis L of the channels 4 is defined by an axis L through the centre 21 of the upper opening 20 in the upper surface 2 and through the centre 31 of the lower opening 30 in the lower surface 3. The respective upper opening 20 and the respective lower opening 30 of the respective channel 4 are horizontally offset. The longitudinal axis L is skewed with respect to the basket bottom 10, e.g. with respect to a horizontal when the portafilter basket is in use, in particular when arranged in a portafilter during extraction.

[0095] Generally referring to Figs 6A and 6B, the wall thickness t of the portafilter basket 1 may be variable over the portafilter basket 1. The thickness t may for example be variable over the bottom 10, side wall 11 and / or support surface 12. This way, reinforced sections 11’, 12’, may be provided, in order to counteract deformation of the portafilter basket 1. Reinforced sections 1 T, 12’ may for example be provided near edges or corners of the portafilter basket 1, for example the edge between the side wall 11 and the support surface 12 and / or the edge between the side wall and the bottom 10.

[0096] The portafilter basket 1 may be manufactured using metal injection moulding. It has been found that metal injection moulding (MIM) allows a large freedom in positioning the channels in the basket, as well as in varying the wall thickness of the basket. In particular, using MIM, the horizontal position and / or a size of the cross section of the channel between the upper opening 20 and lower opening 30 may be varied efficiently. For manufacturing, a metallic basket material may be provided, such as inox, steel or another metallic material. The metallic basket material may subsequently be shaped into a portafilter basket 1 by means of metal injection moulding.

[0097] In use, the basket 1 may be positioned on the portafilter 9. Subsequently the assembly of the portafilter 9 having the basket 1 can be provided with grinded coffee grounds, and be mounted in a coffee machine, such that coffee 93 can be extracted by allowing a fluid, e.g. water, to flow through the ground coffee.

[0098] The scope of the present disclosure is not limited to the embodiments described above. Many modifications therein are conceivable without deviating from the scope of the present invention as defined by the appended claims. In particular, combinations of features of respective embodiments or aspects of the disclosure can be made. An aspect of the invention may be further advantageously enhanced by adding a feature that was described in relation to another aspect of the invention. While the present invention has been illustrated and described in detail with reference to the figures, such illustration and description are illustrative or exemplary only.

[0099] In the claims, the word “comprising” does not exclude other steps or elements, and “a” or “an” does not exclude a plurality. The mere fact that certain measures are recited in mutually different dependent claims does not indicate that a combination of these measures cannot be used to advantage. Any reference numerals in the claims should not be construed as limiting the scope of the present invention.

Claims

CLAIMS1. Portafilter basket (1) for coffee extraction, comprising a basket bottom (10) to be positioned in a portafilter for supporting ground coffee during extraction, wherein the basket bottom comprises: an upper surface (2) provided with upper openings (20); a lower surface (3) provided with lower openings (30); and channels (4) that fluidly connect the upper openings with respective lower openings and thereby allow extracted coffee (93) to flow through the basket bottom (10), characterised in that at least one of the channels (4) is arranged such that a horizontal position of the cross section of the channel is varied between the respective upper opening (20) and lower opening (30).

2. Portafilter basket according to claim 1 , wherein the upper opening and the respective lower opening of the at least one channel are horizontally offset from each other, such that a longitudinal axis (L) of the channel is skewed.

3. Portafilter basket according to the preceding claim, wherein upper openings (20) and the respective lower openings (30) of multiple channels are horizontally offset from each other, and wherein the longitudinal axes (L) of the respective channels are non-parallel to each other.

4. Portafilter basket according to the preceding claim, wherein the channels are arranged at such angles with respect to each other that the respective longitudinal axes (L) converge towards each other and thereby define a focal point (F) in which the longitudinal axes intersect.

5. Portafilter basket according to the preceding claim, wherein a distance between the lower surface and the defined focal point (F) is less than 120 mm, such as 20 - 100 mm, e.g. 50-70 mm.

6. Portafilter basket according to claim 4 or 5, wherein a thickness (t) of the basket bottom (10) is varied over the upper surface, for example such that the length of the channels is dependent on the location of the channels in the basket bottom.

7. Portafilter basket according to any of the preceding claims, wherein the at least one channel is arranged such that a size and / or a shape of the cross section of thechannel is varied between the respective upper opening (20) and lower opening (30).

8. Portafilter according to any of the preceding claims, wherein a wall thickness of the portafilter basket is varied.

9. Portafilter basket according to any of the preceding claims, wherein the channels are defined in the basket bottom by outer walls (40) that are at least partially arranged at a non-perpendicular angle with respect to the upper surface (2) and / or to the lower surface (3).

10. Portafilter basket according to any of the preceding claims, wherein an upper opening surface area of the upper openings (20) and a lower opening surface area of the lower openings (30) differ from each other.

11. Portafilter basket according to the preceding claim, wherein the upper opening surface area is smaller than the lower opening surface area.

12. Portafilter basket according to any of the preceding claims, wherein the at least one of the channels has a diameter of less than 0.3 mm, for example less than 0.2 mm.

13. Portafilter basket according to any of the preceding claims, wherein a cross- sectional shape of the upper openings and a cross-sectional shape of the lower openings differ from each other.

14. Portafilter (9) provided with a portafilter basket (1) according to any of the preceding claims.

15. Coffee machine provided with the portafilter (9) according to the preceding claim.

16. Method for manufacturing a portafilter basket according to any of the claims 1-13 using metal injection moulding, comprising the steps of:- providing a metallic basket material; and- shaping the metallic basket material into a portafilter basket (1) by means of metal injection moulding.

17. Method according to the preceding claim, wherein the step of shaping the metallic basket material comprises forming a basket bottom (10) having at least one channel (4) that is arranged such that a size and / or a shape of the cross section ofthe channel is varied between the respective upper opening (20) and lower opening (30) of the channel.

18. Use of a portafilter basket (1) according to any of the claims 1-13, comprising the steps of:- providing the portafilter basket (1) arranged in a portafilter (9);- arranging ground coffee (95) in the portafilter basket (1); and- extracting coffee (93) by allowing a fluid to flow through the ground coffee.

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