GB2273917A - Beverage foaming device - Google Patents

Abstract

A beverage foaming device which is sealed in a container (bottle or can) together with a beverage under gas pressure comprises a pressurised source 11 of air, beverage or gas positioned between two pistons within a tube and when the container is opened the change in small aperture 17 and the contents of source 11 are pressure causes the lower piston to move to uncover a released into the beverage through aperture 17 as bubbles. The tube is open at both ends and extends from the container base to a level 11b in the head space, a collar 51 holding the tube in position. In a second embodiment the pistons are arranged in two interconnecting cylinders (Figure 6). The second piston maybe locked (74, 76 Figure 6) against movement away from the first piston on pressurisation of the space between the pistons. Another foaming device comprises a drum with a fine aperture in its base (115, Figure 11) and an inner conical formation sealed to the drum base and to the drum top, small perforations (117, Figure 11) connecting the drum interior with the space between the conical formation and the drum wall. The pressurisation of the source of bubbles is generated by pasteurisation of the sealed container or by introducing liquid nitrogen during the filling process. <IMAGE>

Description

BEVERAGE CONTAINERS This invention relates to beverage containers, more particularly for beverages contained under gas pressure such as beer and other alcoholic beverages and carbonated soft drinks.

Especially in the case of beers it is desired to generate or enhance a head on the beverage when opening the container and ways of doing that are described inter alia in GB-1 266 351, WO 91/07326, GB-1 331 425.

Essentially, a source of fine bubbles is sealed into the container with the beverage under gas pressure and the fine bubbles released into the beverage when the container is-opened as a direct result of the loss of gas pressure.

The source of fine bubbles according to the several proposals variously comprises arrangements built in to the container such as an additional compartment formed in the base of a beverage can, as proposed in GB-1 331 425 and devices dropped into the container such as a gas-filled pod inserted into a beverage can at the time of filling the can with beverage, as described in GB-B-2 183 592.

Although GB-A-1 266 351 describes an embodiment comprising a cylindrical gas receptacle which forms part of a "Crown Cap closure and which is necessarily therefore narrower than the inner diameter of the neck of a conventional beverage botle, the usual position for a device is at the bottom of the container because it is clearly best if the fine bubbles enter the beverage at the bottom in order to have maximum effect in the production of a head before they escape from the top of the beverage. Because of obvious limitations, the cylindrical receptacle of GB-A-1 266 351 cannot extend too far down into the container, and this is clearly not regarded as a satisfactory device, as evidenced by the fact that inserts like those of GB-B-2 183 592 and WO 91/07326 are used in cans while no device is commercially available for bottles.

The present invention provides beverage foaming devices which can be realised so as to be capable of use in bottles as well as cans.

The invention comprises in one aspect a beverage foaming device adapted to be sealed in a beverage container together with a beverage under gas pressure and on release of said gas pressure on opening the container to release into the beverage fine bubbles which assist the formation of a head on the beverage, the device comprising a source for the fine bubbles and a fine aperture through which on release of said gas pressure the bubbles are released into the beverage comprised in an elongate hollow rod-like member having a lower end adapted to locate at the base of the upright container and an upper end adapted to locate at the openable top of the container, and the fine aperture being proximate the base of the container.

The said source may be a reservoir of gas at superatmospheric pressure, such gas, as is usual, comprising nitrogen and/or carbon dioxide.

However, the invention also comprises, in another aspect, a beverage foaming device adapted to be sealed in a beverage container together with a beverage under gas pressure and on release of said gas pressure on opening the container to release into the beverage fine bubbles which assists the formation of a head on the beverage, the device comprising a source of compressed air normally kept out of contact with the beverage in the container by gas pressure therein, and a fine aperture through which on release of said gas pressure the air is released into the beverage.

Said source may be comprised in a hollow part of the elongate member which is, while the device is under the gas pressure in the container, maintained out of communication with the fine aperture but which on release of pressure is placed in communication with the fine aperture. The said source may be comprised between seals on a spool slidable in the hollow part. Said spool may be urged by pressure on one end towards an open end of said hollow part on release of container gas pressure. Said one end of the spool may be subject to gas pressure in a compartment of the member and the spool maintained in holding position in the hollow part, with the source out of communication with the fine aperture, by container pressure in the sealed container acting on its other end.The compartment may itself be open to container pressure but through a restricted aperture which allows the spool to be placed in its said holding position but which restricts the escape of gas pressure in the compartment which thereby causes the spool to move out of its said holding position on release of container pressure on its other end.

It is not necessary that air or gas be relesaed into the beverage through the fine aperture, and the invention also comprises, in broad aspect, a beverage foaming device adapted to be sealed in a beverage container together with a beverage under gas pressure and on release of said gas pressure on opening the container to cause the formation of fine bubbles in the beverage which assists the formation of a head on the beverage, the device containing a fluid, which is released through a fine aperture into the beverage in the container on release of said gas pressure, in an elongate hollow rod-like member having a lower end adapted to locate at the base of the upright container and an upper end adapted to locate at the openable top of the container, the fine aperture being proximate the base of the container.

In yet another aspect, the invention comprises a beverage foaming device adapted to be sealed in a beverage container together with a beverage under gas pressure and on release of gas pressure on opening the container to cause the formation of fine bubbles in the beverage which assists the formation of a head on the beverage, the device comprising a first piston which is resiliently biased so as, on release of container pressure, to move under the bias so as to effect entry of fluid from the device into the beverage whereby to cause the formation of the fine bubbles, the first piston being biased by a second piston that is actuated by pressure to apply the bias and latched in the biasing position against releasing the pressure-applied bias.

The pressure used to apply the bias may be pasteurisation pressure - the container pressure in the sealed container will increase when the container and contents are heated to pasteurisation temperature. The container pressure will fall on cooling, but the second piston is latched in the biasing position against releasing the pasteurisation pressure - applied bias as container pressure falls on cooling down after pasteurisation.

The pressure used to apply the bias may however be due to nitrogen which is introduced as liquid nitrogen immediately prior to sealing the can, as by seaming the lid on to the can. The liquid nitrogen is heated by contact with the can contents and nitrogen gas is generated which does not all dissolve in the beverage and gives rise to an internal pressure after sealing, typically twice or three times atmospheric. Such a device can be used where a beverage such as beer is sterile filtered and filled under sterile conditions.

A device which latches at below pasteurisation pressure can, of course, be used in the case of both pasteurisation and sterile filling. Such a device may be adapted to operate whatever filling method is used, or may be adaptable to either filling method by adjustment.

The first piston may cause the formation of fine bubbles by connecting a source of pressurised gas to a fine aperture opening into the beverage. The pressurised gas may comprise air - the air is kept out of contact with the beverage at least until the container, is opened, and so will not spoil a beverage such as beer.

The abilility to use air as the pressurised gas facilitates construction of the device and the operation of filling the container.

The pressurised gas may be contained in the device between the first and second pistons. On release of container gas pressure the first piston may move under the pressurised gas pressure to connect the pressurised gas to the beverage in the container via the fine aperture.

The first piston may be balanced against the resilient bias by container pressure, and may move in a cylinder which has a fine aperture and at least one other opening communicating with container pressure.

The first piston may cause the formation of fine bubbles by forcing a liquid through a fine aperture into the beverage. That liquid may itself comprise beverage, which can be afforded to the device on filling the container.

Experiments have shown that the formation of a head on beer by forcing a liquid (as opposed to a gas) through a fine aperture into the beer is better achieved - perhaps only achieved - if the liquid so forced is itself supersaturated with dissolved gas.

The second piston may work in a cylinder and have a latch member cooperating with a latch retainer externally of the cylinder.

The device may comprise a first cylinder with a first piston and a second cylinder having a larger diameter than said first cylinder and a second piston in said second cylinder, said first and second cylinders being in communication and said first cylinder being open at its end remote from its communication with said second cylinder and said second piston having a piston rod attached to a cup-shaped member surrounding said second cylinder said cup-shaped member having flexible walls and said second cylinder having a detent and said flexible walls having a latch member which can, on pressurisation of the space between said first and second pistons, ride over said detent and latch thereon to lock said second piston against movement away from said first cylinder.

Said first and second cylinders may be coaxial.

Said second piston may have stabiliser means adapted to maintain the second piston axially aligned in the second cylinder. Said stabiliser means may comprise a disc on said piston rod, which may be apertured to prevent air entrapment on filling, or axially extending fins working between said cup shaped member and said second cylinder.

The device may enclose a volume of gas such as air between the first and second pistons which at NTP is about 15-30 ml.

The device may have a maximum non-deformable external cross-section in one direction of about 50 mm to permit insertion into a beverage can before capping the can.

The device, however, may have an elongate configuration of narrow cross-section in which the first piston has a transverse dimension substantially less than its stroke whereby the device may be inserted in a bottle.

A stabiliser collar adapted to contact the inner wall of the container in which the device is sealed may be elastically deformable to permit entry into the container and spring back to engage the said inner wall.

The invention also comprises any of the devices according to different aspects of the invention in operative combination with a beverage container, which may comprise a can or a bottle. The combination may comprise any device with device stabiliser means adapted to limit movement of the device in the container. Such stabiliser means may comprise a collar surrounding the device intermediate its ends.

The device may be comprised in food grade plastics material.

The invention also comprises a method for packaging a beverage in the form of a liquid containing gas in solution in a sealed container comprising the steps of charging in to any of the devices according to different aspects of the invention, said source or cause of fine bubbles and sealing the device and the beverage under gas pressure into the container.

In the case of the device according to the lastmentioned aspect of the invention, with the first and second pistons, air within the space between the pistons is at atmospheric pressure prior to insertion into the open container. On filling, capping and sealing the container it may be subjected to a pasteurisation procedure during which the elevated temperature increases the internal pressure in the container to such an extent as to compress the air between the pistons by movement of the second piston. Such movement of the second piston is arranged to be sufficient to ride the latch member over the latch retainer, thus preventing return movement of the second piston. The air between the pistons falls in pressure as the container cools after the pasteurisa- tion process but is still under the above-atmospheric pressure in the container.On release of container pressure on opening the container, the first piston (which is not latched) is forced along its cylinder to uncover the fine aperture, allowing the air to inject into the beverage in a stream of fine nucleating bubbles.

For cases where the container is not to be subjected to a pasteurisation process, but internal can pressure generated (to say two or three atmospheres) by liquid nitrogen introduced during the filling operation, the latching is arranged to take place at such lower pressure.

Embodiments of a beverage foaming device and methods of packaging a beverage according to the invention will now be described with reference to the accompanying drawings, in which Figure 1 is a longitudinal section through a first embodiment of device; Figure 2 is a section like Figure 1 after the device has been operated to assist in forming a head on a beverage; Figure 3 is a longitudinal section through a can of beverage including the device of Figures 1 and 2; Figure 4 is a view of stabiliser means used in the can of Figure 3; Figure 5 is a longitudinal section through a bottle of beverage including the device of Figures 1 and 2; Figure 6 is a longitudinal section through a second embodiment of device; Figure 7 is a view in the direction of arrow 7 on Figure 6.

Figure 8 is a longitudinal section like Figure 6, after the device has been sealed in a container and the contents pasteurised; Figure 9 is a longitudinal section through a third embodiment of device suitable for a bottle; Figure 10 is a section like Figure 9 after the device has been sealed in a bottle and the contents pasteurised; and Figure 11 is a diagrammatic perspective view of a fourth embodiment of device.

The beverage foaming device 11 illustrated in Figures 1 to 5 is adapted to be sealed in a beverage container such as can 12 (Figure 3) or bottle 13 (Figure 5) under gas pressure. The method of filling the can 12 or bottle 13 is no different to what is normally done except, of course, for the insertion of the device 11.

A gas space 14 is left above the fill level.

The device 11 is adapted on release of said gas pressure on opening the container - by operating the ring-pull 12a of can 12 or by prising off the crown cap closure 13a of bottle 13 - to release into the beverage 15 in the can 12 or bottle 13 fine bubbles which assist the formation of a head on the beverage.

The device 11 comprises a source 16 for the fine bubbles and a fine aperture 17 through which on release of said gas pressure the bubbles are released into the beverage 15.

The bubbles may be of oxygen-free gas such as nitrogen and/or CO2, but, since the bubbles source is normally out of contact with the beverage, in the embodiment illustrated, can even be air.

The device 11 is comprised in an elongate hollow rod-like member having a lower end lla adapted to locate at the base 12b,13b of the upright container 12,13 and an upper end llb adapted to locate at the openable top of the container, the fine aperture 17 being proximate the base 12b,13b of the container 12,13.

As illustrated, the device 11 has its upper end in the gas space 14.

The said source 16 of fine bubbles comprises a reservoir of gas at superatmospheric pressure, the gas comprising as usual nitrogen or carbon dioxide or a mixture of the two, or air as aforementioned.

However, the source of fine bubbles can itself be a liquid, such as the beverage itself, which is forced out of the fine aperture at such a speed as to cause shear forces in the beverage to release gas from the beverage.

The reservoir of gas comprising the source 16 is comprised in a hollow part llc of the elongate member which is, while the device 11 is under gas pressure in the container 12,13, maintained out of communication with the fine aperture 17 but which on release of pressure placed in communication with the fine aperture 17. The source 16 is comprised between seals 18a on a spool 18 slidable in the hollow part llc.

The spool 18 is urged by pressure on one end 18b towards an open end - the lower end lla of the hollow part llc of the device 11 on release of container gas pressure. The said one end 18b is subject to gas pressure in a compartment lld of the device 11 and the spool 18 is maintained in holding position (Figure 1) in the hollow part llc with the source 16 out of communication with the fine aperture by container pressure in the sealed container 12,13 acting at its other end 18c.

The said compartment lld is itself open to container pressure but through a restricted aperture Ile in the closed upper end llb of the device 11. This allows the spool 18 to be placed in its holding position by allowing escape of gas but restricts the escape of gas pressure from the compartment lld when container pressure is released on opening the container 12,13.

Pressures within the container 12,13 and within the compartment lld and below the end 18c are in equilibrium at a superatmospheric pressure until the moment the container is opened, when container pressure falls suddenly to atmospheric. The superatmospheric pressure of the bubble source gas between the spool ends 18b,18c (which may be higher or lower than the container pressure) is not directly affected at this time, and the pressure in the compartment 11d can only be relieved very slowly through the restricted aperture lle. As a result the compartment lld pressure on end 18b of spool 18 is greater than the pressure on the opposite end 18c and the spool moves under the pressure differential towards the open end lla of the device 11, being there arrested by a stop llg.

This movement puts the source 16 in communication with the fine aperture 17 and since the source gas pressure is still superatmospheric, fine bubbles of air or other gas jet out from the fine aperture 17 into the beverage 15. The bubbles form nuclei on which dissolved gas in the beverage comes out of solution following loss of container pressure.

The device 11 has been described on the basis that the container 12,13 is upright and the device 11 maintained upright in the container 11,12. Since the device 11 is elongate and narrow relative to the diameter of a can, it is desired to restrict its movement somewhat at least to which end a collar 41 is used as a stabiliser. The collar 41 comprises flexible tags 42 allowing it to be pushed into the can 12 before the top of the can is applied and sealed. The collar 41 could be inserted before or after or together with the device 11 as convenient.

With a ring-pull can, there will be no risk that the device 11 will fall out on pouring the beverage, but such a risk arises with a bottle and Figure 5 shows a flexible collar 51 that grips the device 11 and is wider than the neck of the bottle 13 so that once it is pushed in with the device 11 it will not fall out on pouring.

With the device 11 upright in the upright container 12,13 the top llb and the restricted aperture lle of the device 11 are in the gas space 14. Gas, moreover, is present in the device 11 below the lower end 18c of the spool 18, though because of the hydrostatic head of the beverage, there will be a slight intrusion of beverage into that space, which will be in the form of a meniscus M as seen in Figure 1. The container 12,13 might of course be upturned during storage or transportation and then any gas trapped in that lower end of the device will be able to escape and be replaced by beverage. This will be of no consequence, however - the beverage in such space will be displaced through the wide open end lla of the device by the moving spool 18.

Upturning the container 12,13 will also submerge the upper, closed end llb and the restricted aperture 11e in beverage but this will be of no consequence either because the beverage 15 will be unable to penetrate the restricted aperture lle, which is required only to permit the escape of gas under the pressure generated by pushing the spool 18 into the device 11 and once the can is sealed the equilibrium pressure conditions are maintained. It is, of course, essential only that the fine aperture 17 is submerged in the beverage on opening the container to allow the fine bubbles to emerge into the beverage to create their desired effect, but the container must in any event be upright or reasonably so for opening in order to prevent the beverage from spilling out.

Typical gas pressures in the sealed container are about two to three times atmospheric, but could be higher. The gas pressure in the compartment Ild will be able, therefore, to displace the spool 18 so that the seal 18a at its lower end passes the fine aperture 17 to place the space llc in communication with the fine aperture 17.

As suggested in WO 91/07326 an aperture of about 0.1 mm diameter will serve well as the fine aperture 17. GB-B-2 222 569 suggests for a similarly-purposed aperture a diameter of 0.25 to 0.38 mm, which permits beverage to enter a secondary chamber. The optimum size can of course be determined by experimentation and may depend on the nature of the container, the dimensions of the device, the pressure under which the beverage is packaged in the container and the kind of head desired.

The beverage can be packaged in the container, as mentioned, under the conditions and by the techniques customarily used, which will at least with alcoholic beverages involve measures to exclude oxygen from the packaging. It is necessary, then, to exclude oxygen likewise from the various parts of the device 11.

The spool may be automatically inserted into the body of the device in an atmosphere of pressurised nitrogen, for example, trapping pressurised nitrogen in the space between the seals 18a, and mechanically pushed beyond the fine aperture 17, then the stop llg attached.

If the then charged device needs to be brought temporarily into a normal atmosphere before being loaded with the beverge into the container, any oxygen contamination resulting therefrom can be dealt with by the measures taken in any event to exclude oxygen from the container.

On the other hand, since the gas in the space between the seals 18a would normally be kept out of contact with the beverage, it may be more convenient to fill the space with air. This has the possible advatange of conforming to the practice of aerating beverages on draught by entraining air into the tap flow, though the amounts of gas involved may be so small as to be almost insignificant.

As mentioned also, beverage itself could be comprised in the space between the seals, triggering release of gas from solution in the beverage by the shear forces generated on its high speed release into the beverage under pressure.

While the embodiment described and illustrated is simple in construction and inexpensive to manufacture and use, yet is particularly effective for cans and bottles of all sizes, variations in the design will obviously be possible within the overall concept.

The device will preferably be comprised in a food-grade plastics material. While it is not visible when used in a can or a dark-coloured glass bottle, it may well be desired to be visible, used in clear glass bottles, so that its operation can be observed.

The beverage foaming device 61 illustrated in Figures 6, 7 and 8 is adapted to be sealed in a beverage can 62 (shown in broken line) together with a beverage 63 under the pressure of gas in the space 64 - usually N or CO2 or a mixture, oxygen being excluded so as not to cause deterioration of the beverage.

The device 61 is adapted on release of gas pressure on opening the can 62 (as by a ring-pull arrangement in the end of the can 72, not shown) to cause the formation of fine bubbles in the beverage which assists the formation of a head on the beverage.

The device 61 comprises a first piston 65 which is resiliently biased - via gas pressure with the device in the configuration of Figure 8 - so as, on release of can pressure, to move under the bias (in the direction of the arrow attached to it in Figure 8) so as to effect entry of fluid from the device - the fluid being air in this embodiment - into the beverage 63 whereby to cause the formation of fine bubbles.

The first piston 65 is biased - via gas pressure as mentioned above - by a second piston 66 that is actuated by pressure to apply the bias - by compressing the gas between the pistons 65,66 - and latched in the biasing position (Figure 8) against releasing the pressure-applied bias. The bias-applying pressure may be pasteurisation pressure, the device being latched against releasing the bias when can pressure is relieved through cooling after pasteurisation. The bias-applying pressure may however be generated by the evaporation of liquid nitrogen introduced into the can just prior to seaming on the lid.

The device 61 is dropped into a can while charging the can with beverage, the device 61 being at this stage in the configuration illustrated in Figure 6. When the can is capped and sealed and heated for pasteurisation purposes, the internal pressure increases - to around 600 kPa - and this compresses the gas between the pistons 65,66 by moving the larger, second piston 66, the first piston 65 being already located against the end 67 of its cylinder 68, which is itself open to can pressure at its other end 69. The second piston 66 moves as far under pasteurisation pressure as to latch it against return, as will hereinafter be explained.

On cooling after pasteurisation the can pressure falls to around 270 kPa. On eventual opening of the can, the internal pressure falls and the pressure in the space between the pistons 65,66 forces the first piston 65 towards the end 69 of its cylinder 68. In the cylinder 68, near the end 67, but closed by the piston 65 when located against that end, is a fine aperture 71 through which, when the can is opened and the piston 65 uncovers the fine aperture 71, the gas between the pistons enters the beverage, giving rise to the formation of fine bubbles which assists formation of a head on the beverage.

Since the gas between the pistons 65,66 is, until the moment of opening the can, kept out of contact with the beverage, it can safely comprise air, so that no special filling procedures under nitrogen flush or with CO2 or a mixture of nitrogen and CO2 are required in the production of the device 61.

It could, instead, be arranged that the movement of the first piston, as a result of the overpressure between the pistons when can pressure is released on opening, jets a liquid - which might be the beverage itself - into the beverage instead of a gas. Such a jet would also have the effect of causing fine bubbles to appear as a result of turbulence causing dissolved CO2 to come out of solution though it seems to be better if the liquid is supersaturated with a gas so that as it jets into the beverage the dissolved gas comes out of solution. Beverage could be introduced during can filling or pasteurisation into a compartment of the devide 61, for example by arranging that there is only one aperture to the cylinder 68 in which piston 65 moves, that being a fine aperture at the end 69. The piston 65 could be initially located at that end 69 and displaced away from that end by increasing can pressure on pasteurisation, drawing beverage into the cylinder 68 through the fine aperture - which operation could be facilitated by having the fine aperture in a valve at the end 69 that opened to admit beverage but closed due to overpressure in the cylinder 68 as the piston 65 moved towards the end 69 on release of can pressure on opening.

The latching arrangement for the second piston 66 is afforded by a cup-shaped member 72 attached to rod 66a of piston 66 which surrounds the cylinder 73 in which piston 66 works, and which has a latch member 74 on flexible walls 75 of the cup shaped member that can, on pressurisation of the space between the first and second pistons, travel along the walls of the cylinder 73 and ride over a detent 76 on the end thereof and latch thereon.

Conveniently for manufacture, the said first and second cylinders 68 and 73 are coaxial. The second piston 66 has a stabiliser disc 77 on its piston rod 66a which works in the cylinder 73 spaced from the piston 66.

The disc is apertured as shown at 77a to ensure against air entrapment during filling. Another arrangement maintaining the piston 66 coaxial in the cylinder 73 comprises axially-extending fins 81 on the inner wall of the cup-shaped member 72 which run on the outer wall of the cylinder 73.

The volume of gas or air between the first and second pistons at NTP - which is to say, before the device 61 is "primed" by pasteurisation or otherwise, the volume of the space between the pistons - is about 15-30 ml.

The device 61 is intended for use in beverage cans such as cans of beer, lager, stout and the like that traditionally have a head when served from draught whereby the canned beverage more closely approximates the draught. To fit in such cans the maximum nondeformable axial cross-section is about 50 mm. An elastically deformable stabilising collar 78 is located on the end 69 of the cylinder 68 which has fingers best seen in Figure 7 - which reach out to the inner walls of the can to hold the device 61 in position therein so that it does not disclose its presence by rattling or by rising to the top of the can on opening the can, which occurrence might in any event interfere with satisfactory pouring and might also prove less effective at head formation than if the device is held low down in the can.

Figures 9 and 10 illustrate a device 91 which operates in like manner to that illustrated in Figures 6 to 8 but which has an elongated configuration of narrow cross-section in which the second piston 66 has a transverse dimension substantially less than its stroke whereby the device may be inserted in a bottle (not shown) with the piston 66 lowermost. The latch arrangement in this embodiment comprises a ramped detent 93 internally of the cylinder 94 in which piston 66 works and a deformable seal 95 on the piston 66 that can move over the ramp during pasteurisation or otherwise increasing the bottle pressure but cannot move back.

The device illustrated in Figure 11 comprises a drum 111 having a top 112, a base 113 and a sidewall 114, the base 113 having a small performation 115 allowing ingress or egress of gas or liquid under external pressure changes. Internally, the drum 111 has a part conical formation 116 sealed to the top 112 and base 113 with small performations 117 establishing communication between the space 118 inside the conical formation 116 and the space 117 between the conical formation 116 and the side wall 114.

In use, the drum 111 is placed base down in a beverage containing can which is then pasteurised. On account of the increase in internal pressure in the can resulting from the pasteurising temperature, beverage is forced into the drum through the performation 115 and fills the space 119 up to the level of the perforations 117 where it overflows into the space 118.

On cooling, the beverage in the space 119 is slowly forced out of the drum 111 through the basal perforation 115. The configuration of the device is such that, taking into account the internal can pressure attained during pasteurisation and the pressure remaining after pasteurisation, the beverage in the space 119 is completely expelled, but no air is expelled from the drum 111 into the beverage in the can.

On eventually opening the can, the internal can pressure falls rapidly, leaving an overpressure in the drum 111. The air in the drum is expelled via the basal orifice 115 generating the desired head. Beverage still contained in the space 118, which will have been contaminated and spoiled by being exposed to the air in the drum 111, will be prevented ever from reaching the beverage in the can.

Claims (23)

1. A beverage foaming device adapted to be sealed in a beverage container together with a beverage under gas pressure and on release of said gas pressure on opening the container to release into the beverage fine bubbles which assist the formation of a head on the beverage, the device comprising a source for the fine bubbles and a fine aperture through which on release of said gas pressure the bubbles are released into the beverage comprised in an elongate hollow rod-like member having a lower end adapted to locate at the base of the upright container and an upper end adapted to locate at the openable top of the container, and the fine aperture being proximate the base of the container.

2. A device according to claim 1, in which the first piston causes the formation of fine bubbles by connecting a source of pressurised gas to a fine aperture opening into the beverage.

3. A device according to claim 2, in which the pressurised gas comprises air.

4. A device according to claim 2 or claim 3, in which the pressurised gas is contained in the device between the first and second pistons.

5. A device according to claim 4, in which on release of container gas pressure the first piston moves under the pressurised gas pressure to connect the pressurised gas to the beverage in the container via the fine aperture.

6. A device according to any one of claims 1 to 5, in which the first piston is balanced against the resilient bias by container pressure.

7. A device according to claim 6, in which the first piston moves in a cylinder which has a fine aperture and at least one other opening communicating with container pressure.

8. A device according to any one of claims 1 to 7, in which the first piston causes the formation of fine bubbles by forcing a liquid through a fine aperture into the beverage.

9. A device according to claim 8, in which the liquid comprises beverage.

10. A device according to any one of claims 1 to 9, in which the second piston works in a cylinder and has a latch member cooperating with a latch retainer externally of the cylinder.

11. A device according to any one of claims 1 to 10, comprising a first cylinder with a first piston and a second cylinder having a larger diameter than said first cylinder and a second piston in said second cylinder, said first and second cylinders being in communication and said first cylinder being open at its end remote from its communication with said second cylinder and said second piston having a piston rod attached to a cup-shaped member surrounding said second cylinder said cup-shaped member having flexible walls and said second cylinder having a detent and said flexible walls having a latch member which can, on pressurisation of the space between said first and second pistons, ride over said detent and latch thereon to lock said second piston against movement away from said first cylinder.

12. A device according to claim 11, in which said first and second cylinders are coaxial.

13. A device according to claim 11 or claim 12, in which said second piston has a stabiliser disc on said piston rod which works in said second cylinder spaced from said second piston.

14. A device according to any one of claims 1 to 13, enclosing a volume of air between the first and second pistons which at NTP is about 30 ml.

15. A device according to any one of claims 1 to 14, having a maximum non-deformable external cross-section in one direction of about 50 mm to permit insertion into a beverage can before capping the can.

16. A device according to any one of claims 1 to 14, having an elongate configuration of narrow cross-section in which the second piston has a transverse dimension substantially less than its stroke whereby the device may be inserted in a bottle.

17. A device according to any one of claims 1 to 16, having a stabiliser collar adpated to contact the inner wall of a container in which the device is sealed.

18. A device according to claim 17, in which the collar is elastically deformable to permit entry into the container and springs back to engage the said inner wall.

Amendments to the claims have been filed as follows

19. A beverage foaming device adapted to be sealed into a beverage container together with a beverage under gas pressure and, on release of said gas pressure upon opening the container to release into the beverage fine bubbles, which assists the formation of a head on the beverage, the device comprising a source of compressed gas normally kept substantially out of contact with the beverage in the container by gas pressure in the container acting on a displaceable seal arrangement so that any oxygen present in said compressed gas will not affect the beverage in the container into which the said compressed gas is to be released, and a fine aperture normally held out of gas communication with the compressed gas by the displaceable seal arrangement but placed in communication therewith by displacement of the seal arrangement to allow the compressed gas to flow through the fine aperture into the beverage.

20. A device according to claim 19, in which the seal arrangement is comprised by beverage in a restricted fluid passage in the device, such beverage being introduced into the passage during the operation of filling the container.

21. A device according to claim 20, comprising a drum having a basal perforation allowing ingress or egress of gas or liquid the basal perforation being connected to a hollow space in the interior of the drum by said restricted fluid passage.

22. A device according to claim 21, in which the drum has a part conical formation sealed to a top and a base with small perforations establishing communication between the space inside the conical formation and the space between the conical formation and the side wall.

23. A beverage container can containing a beverage foaming device comprising a drum having a top and a base with a basal perforation into which drum beverage is forced by increase in pressure in the container due to pasteurisation through the perforation to fill a first space within the drum up to a level where it overflows into a second space within the drum, the level being such that on cooling after pasteurisation the beverage in the first space is completely expelled but no air is expelled from the drum into the beverage in the can.