GB2539929A - Coffee capsule - Google Patents

Abstract

A capsule 1 for a beverage machine adapted to operate at a pressure of around 19 bar, the capsule having a generally frusto-conical form with an annular flange 4 at its lower end, a foil 3 being provided to sealingly close the capsule at its lower end, with said foil being attached to the flange. The foil 3 is embossed so that the foil has an effective depth greater than the foil thickness, such that the effective depth of the foil 3 is greater than 0.06 mm and less than 0.13 mm. The foil is adapted to be torn when in use the pressure in the capsule is between 3 and 8 bar. The capsule can be air-tight. The foil embossing may be in the form of points or areas covering at least 10% of the surface of the foil. The embossing may be such that the effective depth of the foil is at least twice the thickness of the foil.

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.

Either type of capsule is sealed at its open end with a foil, typically aluminium, which foil is sealingly attached to the rim of capsule and which in use is tom by projections on a filter plate. The foil is caused to press against these projections by the increase in pressure inside the capsule as described above. It has been proposed to control the coffee flow by the use of a filter material on the inside of the capsule adjacent to or on the foil in EP2100824 and WO2010076048. The use of the filter material is effective but increases the cost of the capsule and also affects its recyclability, which is a significant consumer concern and technical problem.

According to the invention there is provided a capsule for a beverage machine adapted to operate at a pressure of around 19 bar, which capsule has a generally frusto-conical form with an annular flange at its lower end, a foil being provided to sealingly close the capsule at its lower end, which foil is attached to the flange, wherein the pressure inside the capsule is equal to or greater than atmospheric pressure, which foil is adapted to be tom when, in use, the pressure in the capsule is between 3 and 8 bar, wherein the foil is embossed so that the foil has an effective depth greater than the foil thickuess, such that the effective depth of the foil is greater than 0.06 mm and less than 0.13 mm

Preferably the capsule is substantially air-tight. Preferably the effective depth is between 0.06mm and 0.13 mm, more preferably 0.07 to 0.09mm.

Preferably, the embossing comprising a plurality of embossed points or areas on the foil. Preferably, the points or areas cover at least 10% of the surface area of the foil.

In a capsule producing machine, the capsule body is first packed with coffee before the seal is applied to the rim in an inert atmosphere to prevent air from being sealed into the capsule which would result in the coffee becoming stale. It has surprisingly been discovered that embossing the foil has a significant effect on flow rates from the capsule. The ability to emboss a capsule foil is commercially significant as it enables branding to be put on the capsule during the capsule ma process. This in turn eliminates the need to have separate foil material for each type of coffee or beverage, which reduces material costs and increases capsule machine utilisation rates.

It has been surprisingly found that the depth of the embossing has a material effect on the flow rate of the coffee. Although in principle a longer flow time is beneficial in the extraction process, if the flow rate is too long the pressure build up in the capsule can cause the pump to stall.

An exemplary embodiment 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 side view of the capsule

Figure 1 shows a perspective side section of capsule 1 having a generally frustoconical form. 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 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 polybutylene terephthalate, 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 first and second annular upstanding walls spaced from one another. In use the capsule cage walls bear against at least one of the upstanding walls.

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 6 when the outer diameter increases by a small amount to provide a shoulder to the rim of the capsule.

Alternatively, it would 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 these examples, a plastic capsule is used and the unembossed foil material is 0.03mm thick. The smooth foil will flow at 10 seconds for a standard espresso extraction using a Nespresso Inissia ® machine. The coffee machine pump is pressure controlled and will supply water until the pressure at the pump outlet reaches 19 bar at which point the pump automatically switches off. If the capsule foil is given a light emboss of 0.03mm to give effective depth of material of 0.06mm, the flow time will increase to 18 secs with the same coffee and capsules and volume of water. The embossing also reduces the likelihood of the smooth foil tearing.

For a heavy emboss of 0.09mm the flow time is increased to 25sec with same grind coffee and capsules and volume of water.

The depth of the emboss thus has a real slowing effect in how the foil breaks and the resultant flow rate of coffee out of the brew head. The preferred flow time for a standard pump operation is 18 to 22 seconds.

In use the capsule can be inserted in a conventional machine and the arrangement of the zone of weakness enables the upper surface of the capsule to be tom 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 (7)

Claims

1. A capsule for a beverage machine adapted to operate at a pressure of around 19 bar, which capsule has a generally frusto-conical form with an annular flange at its lower end, a foil being provided to sealingly close the capsule at its lower end, which foil is attached to the flange, wherein the pressure inside the capsule is equal to or greater than atmospheric pressure, which foil is adapted to be torn when, in use, the pressure in the capsule is between 3 and 8 bar, wherein the foil is embossed so that the foil has an effective depth greater than the foil thickness, such that the effective depth of the foil is greater than 0.06 mm and less than 0.13 mm.

2. A capsule according to Claim 1, wherein the capsule is substantially air-tight.

3. A capsule according to Claim 1 or Claim 2, wherein the effective depth is between 0.06mm and 0.13 mm, more preferably 0.07 to 0.09mm.

4. A capsule according to any one of Claims 1 to 3, wherein the effective depth is at least twice the thickness of the foil.

5. A capsule according to any one of Claims 1 to 4, wherein the embossing comprises a plurality of embossed points or areas on the foil

6. A capsule according to any one of Claims 1 to 5, wherein the points or areas cover at least 10% of the surface area of the foil.

7. A capsule substantially as described herein with reference to and as illustrated in the accompanying drawings.