GB2545569A

GB2545569A - Coffee capsule

Info

Publication number: GB2545569A
Application number: GB1620960.3A
Authority: GB
Inventors: Gort-Barten Leslie
Original assignee: Individual
Current assignee: Individual
Priority date: 2013-10-16
Filing date: 2013-10-16
Publication date: 2017-06-21
Anticipated expiration: 2033-10-16
Also published as: GB2545569B; GB201620960D0

Abstract

A coffee capsule having a fursto-conical form, with an upper and lower surface, an annular flange 4 on a lower surface provides a sealing means comprising first 5 and second 6 spaced apart walls, where the capsule is provided with an annular zone of weakness 2. Preferably, the upper surface of the capsule is torn by water pressure from the coffee machine. Preferably, the capsule wall is 0.8mm thick and the zone of weakness is 0.5mm thick. Preferably, the zone of weakness has a stepped profile, so that the wall is thicker near the edge. Preferably, the capsule is made from food grade plastic. Preferably, the capsule is flushed with nitrogen prior to being filled.

Description

Coffee Capsule

The invention relates to a capsule for making espresso coffee using an espresso machine.

Powered espresso machines are well known. The conventional espresso machine comprises a water chamber, a heating element adapted to heat the water to around 95-98 C, which is then pumped under high pressure of 15 to 19 bar to a filter holder or portafilter. Lower pressure systems also exist. The filter holder typically comprises a handle portion and a holder portion provided with two or three lugs that are adapted to engage in the installed position with the machine brewhead to where the water is pumped. The holder portion is adapted to receive a filter, which is usually a metal bowl with a number of perforations through its bottom. In use, the filter is filled with finely ground coffee and the water is forced through the coffee at the high pressure generated by the pump to produce the espresso coffee which is collected in a cup placed under the filter holder.

The classic coffee machine suffers from two potential drawbacks. The first drawback is that ground coffee starts to lose its freshness and flavour after a few days and so for the optimum espresso, the user will also need to have a coffee grinder. The other drawback is that the used espresso coffee has to be removed from the filter, which can lead to mess as the grinds are fine.

This lead to the development of ESE coffee pods, which can be used in many espresso machines. Coffee pods are generally individually wrapped to maintain freshness and consist of a small pod made of a perforated filter paper which contains the coffee. The pod is placed in the filter holder and then disposed of after use. Coffee pods are convenient but have to fit the filter holder and be placed correctly otherwise water can leak around the edge.

This in turn lead to the development of capsule machines. The coffee capsules for these machines are completely sealed. The capsule machines do not use the conventional filter holder. A capsule machine typically has a two part mechanism. The first part receives the capsule and is provided with an extraction surface upon which the capsule rests. The second part is provided with a locking lever which is used to make the first and second parts integral. In use, the second part cuts the upper surface of the capsule to allow water to enter the capsule and percolate down through the capsule, where it exits through the lower surface of the capsule at multiple locations determined by the geometry of the extraction surface. An example of such a machine is disclosed in EP 0870457 or W02005/004683. Capsules in the known capsule coffee machines are, in use, inserted into a capsule cage of the machine which holds the capsule in position so that it may be cut by a cutting member.

Capsule machines have proved to be commercially very successful as they are very convenient to use and produce a consistent product. However, each manufacturers coffee machines and capsules are designed to work with the manufacturers own brand. The most popular brand of capsule is Nespresso ®, which uses a sealed capsule. In use, the capsule is clamped into position in the machine with a capsule cage part holding the capsule so that it can be cut by three prongs to enable water under pressure to enter the coffee capsule. The main alternative to this type of capsule is perforated with 6 to 9 holes to enable the water to enter the capsule. The perforations have one significant design drawback in that air can enter the capsule. Consequently, the capsules are packaged in small quantities in nitrogen filled bags to enable the shelf life of the coffee to match that of a sealed capsule. This results in significantly increased transport and packaging costs. A particular problem with capsule systems is ensuring a tight fit between the capsule cage and the capsule rim in the extraction position. Early solutions relied on simple mechanical pressure but more recent capsules have used a rubber elastic seal such as silicone around the rim due to changes in capsule cage design. In use the capsule cage is applied to the seal to ensure that there is no loss of pressure. This seal has been effective but adds considerably to the production costs of the capsule.

It has been further proposed to use a series of deformable concentric rings formed on the rim, which in use are engaged by the capsule cage and deflected to ensure a pressure tight seal. However, the concentric rings need to be closely spaced and if a plastic capsule is used, then in production the capsule often sticks to mould. Removing the capsule then results in wear to the tool.

The present invention seeks to provide a coffee capsule with an improved seal.

According to the invention there is provided a capsule for use in a coffee machine having a generally frusto-conical form with an upper surface and a lower surface, an annular flange being provided at the lower surface, which annular flange is provided with sealing means on the surface facing towards the upper surface, wherein the sealing means comprises first and second walls spaced from one another and adapted to engage with an element of a coffee machine capsule cage, wherein the capsule is provided with an annular zone of weakness.

Preferably, in use, the upper surface of the capsule is tom by water pressure from the coffee machine. Preferably, the capsule wall is generally about 0.8mm thick and the wall around the zone of weakness is about 0.5mm thick.

Preferably, the zone of weakness has a small stepped profile so that the wall is thicker near the edge of the zone of weakness. Preferably, the capsule is made of food grade plastic. Preferably, the capsule is flushed with nitrogen prior to being filled

Exemplary embodiments of the invention will now be described with reference to the drawings, in which:

Fig. 1 shows a perspective view of the capsule Fig. 2 shows a top view of the capsule Fig. 3 shows an alternative capsule

Figure 1 shows a perspective side section of capsule 1 having a generally frustoconical form and Figure 2 shows a top view of the same capsule. The upper end of the cone frustrum has a smaller diameter than the lower end. The surface of the upper end of the cone is provided with a zone of weakness 2 in the form of an annular groove on the outer surface of the capsule. In use, cutting members of the capsule machine will sit just above the surface of the groove but do not pierce the capsule so that in use the water pressure bursts the weakened section and creates the path for the water to ingress the top of the capsule and into the coffee. In a manual machine that does not have cutting members, the water will simply tear or break the capsule at the zone of weakness.

If the capsule is made of a food grade plastic such as polypropylene, this arrangement substantially reduces air movement between the inside and the outside of the capsule thereby greatly extending the time that the coffee in the capsule retains its aromas. In use, the capsule should be flushed with nitrogen prior to being filled to prevent oxygen degrading the quality of the coffee. This in turn enables the producer to achieve an acceptable shelf life for the coffee without the use of a nitrogen filled pillow bag. In a particularly preferred embodiment the capsule wall is generally about 0.8mm thick but the wall around the zone of weakness is only about 0.5mm thick. The interior surface of the upper end has a small stepped profile in the region of the zone of weakness, so that the wall is thicker near the edge of the groove. This encourages the wall to tear near the centre of the groove or undercut rather than at the edge.

The lower end of the capsule is provided with a foil seal 3, which foil seal, in use, is pressed against a filter element typically comprising a plurality of the upstanding truncated pyramids and adapted to assist in the tearing of the foil in use so that the coffee extracted from the coffee granules can percolate out of the capsule through holes in the filter.

The interior of the capsule is provided with several strengthening ribs to reduce the likelihood of the capsule collapsing under the pressures to which it is subjected in use. The pressure on the inside of the capsule is typically in the range of 3 to 8 bar depending on the coffee machine and the packing density of the coffee in the capsule. This pressure is sufficient to cause the foil to tear against a filter plate in the coffee machine.

The capsule is provided with a flange 4 at its lower end, which flange 4 is adapted to co-operated with a retaining mechanism of a coffee machine in use so that the capsule can be held in the correct position when in use in the coffee machine. The flange is provided with a first upstanding wall 5 spaced from the exterior of the frusto-concial wall 6 of the capsule. In use the capsule cage walls bear against at least one of these upstanding walls. A further zigzag wall 7 is provided between the first and second walls. The angle between the adjacent wall elements is between 60°. and 120°, most typically around 90° The zigzag wall 7 is deformable by the action of the capsule cage and provides for an improved seal compared to the concentric circles of the prior art as the capsule cage mouth is typically castellated and the zigzag pattern engages with the castellations in a sealing fashion. The zigzag wall need not be substantially vertical or upstanding but could also be at an angle to the flange surface. It would also be possible for the first 5 and second 6 walls and the zigzag wall 7 to be cut from the surface of a thicker flange. The upstanding walls are generally around 0.5-0.6mm high but could potentially be in the range 0.2 - 1.2 mm .

Figure 3 shows an alternative capsule to that shown in Figures 1 and 2. The capsule is provided with a flange 4 at its lower end, which flange 4 is adapted to co-operated with a retaining mechanism of a coffee machine in use so that the capsule can be held in the correct position when in use in the coffee machine. The flange is provided with a first upstanding wall 5 spaced from the exterior of the frusto-conical wall 6 of the capsule. In use the capsule cage walls bear against at least one of these upstanding walls. Radial webs 8 are provided between the first wall 5 and the exterior of the frusto-conical wall 6. The radial webs are spaced around 1mm apart.

The capsule does not have a regular conical outer diameter over its entire length. The outer diameter of the upper part of the capsule is initially vertical and increases at a first rate until it reaches shoulder 8 when the outer diameter increases by a small amount to provide a shoulder to the rim of the capsule. The radial webs are generally around 0.5-0.6mm high but could potentially be in the range 0.2 - 1.2 mm.

It would be possible to provide the wall 7 or webs 8 with a chamfered edge, a round edge or

It would also be possible to have the outer diameter of the capsule increase at a second rate greater than the first rate until the rim of the capsule.

In use the capsule can be inserted in a conventional machine and the arrangement of the annular zone of weakness enables the upper surface of the capsule to be torn by water pressure from the espresso machine without the need for a cutting device. The capsule is therefore suitable for use in conventional espresso machines as well as capsule machines as the pressure of the water will force the foil against the filter plate of the espresso machine to enable the extracted coffee to percolate out of the capsule.

Although the capsule has been specifically described as being used to make espresso coffee, it would be possible to make other beverages such as tea or chocolate.

Claims

1. A capsule for use in a coffee machine having a generally frusto-conical form with an upper surface and a lower surface, an annular flange being provided at the lower surface, which annular flange is provided with sealing means on the surface facing towards the upper surface, wherein the sealing means comprises first and second walls spaced from one another and adapted to engage with an element of a coffee machine capsule cage, wherein the capsule is provided with an annular zone of weakness.

2. A capsule according to Claim 1, wherein, in use, the upper surface of the capsule is torn by water pressure from the coffee machine.

3. A capsule according to Claim 1 or Claim 2, wherein the capsule wall is generally about 0.8mm thick and the wall around the zone of weakness is about 0.5mm thick.

4. A capsule according to any one of Claims 1 to 3, wherein the zone of weakness has a small stepped profile so that the wall is thicker near the edge of the zone of weakness.

5. A capsule according to any one of Claims 1 to 4, wherein the capsule is made of food grade plastic.

6. A capsule according to any one of Claims 1 to 5, wherein the capsule is flushed with nitrogen prior to being filled.