Method of inserting a gas-jetting capsule into a beverage can having a reduced diameter neck

Abstract: Devices are described for fitting into pressurised packaged beverages (typically canned beers, ales and stouts), by which gas at high pressure is stored within the package for jetting into the beverage as the package is opened to atmosphere. One embodiment comprises a moulded plastics capsule (34; 50; 78) secured near the bottom of a can (20; 88) with an internal, preferably central, pipe (56; 62; 80) to provide a liquid seal to prevent loss of gas when the can is inverted from the upright position, and an airlock when the can is upright, to prevent beverage which has entered the capsule from leaving it when the cam is opened to atmosphere. A further design of capsule (96), having a central internal pipe (98) and adapted to be pressurised solely by the ingress of beverage, is fitted midway down a can (94) but still only jets gas upon opening. A method of inserting the capsule is also described.

Description: Field of invention This invention concerns a method of inserting a gas-jetting capsule into a beverage can having a reduced diameter neck. This invention is of particular application to canned beers particularly of the type containing dissolved nitrogen and carbon dioxide. The expression beer is intended to include any alcoholic beverage such as ale, beer, porter, stout and the like. Background to the invention It is characteristic of some alcoholic beverages especially stout and traditional ales and beers to generate a foamy head of gaseous bubbles during the dispensing of the beverage into a glass and to consume the drink with this head evident upon the liquid. The source of gas for the bubbles is the gases dissolved in the beverage which are caused to break out of solution through a nucleation process. When dispensing from the bar this nucleation process has been stimulated by forcing the beverage under very high pressure through small nozzles which create sufficient sheer force to stimulate gas nucleation. It is also known that if nitrogen is dissolved in such beverages the bubbles are smaller, more stable and are perceived as creamier than when only carbon dioxide is present. It has therefore become common practice to add nitrogen to certain beers, ales and stouts. To maintain the nitrogen in solution, nitrogen has been used in the gas over pressure dispensing systems for dispensing such beverages so as to promote a stable and creamy head. It has also become commonplace to add nitrogen to canned alcoholic beverages as aforesaid and to pressurise the can with nitrogen to the extent of adding liquid nitrogen during filling, so that after the can is sealed the evaporating dose of liquid nitrogen will increase the internal pressure typically to two atmospheres or more. The can pressurisation has enabled thinner walled cans to be used and the use of non-oxidising gas for the pressurisation (after purging the can and contents of all oxygen), has ensured that oxygen will be absent from the interior of the can. If nitrogen is used, it will be taken up by, and become dissolved in the beverage, so that if the latter can be stimulated to give up the nitrogen on dispensing, a rich creamy head of nitrogen bubbles will be formed on the beverage. Various techniques have been adopted to stimulate the bubble formation on dispensing from such a pressurised can. Early attempts are described in GB 1266351 particularly in relation to Figure 3, wherein a secondary chamber is defined within the can which is adapted to retain a charge of gas under pressure, which discharges into the beverage through a fine orifice, driven by the pressure difference arising immediately after the can is opened to atmospheric pressure by the consumer. Practical difficulties with this described technique apparently prevented commercial application for many years. The problems included the complexity and cost of modification to standardise packaging, the necessity to develop specialised can or bottle filling equipment for non-standard packages, the necessity to minimise oxygen in the package usually causes a beverage to change in flavour, the requirement that there should be minimal reduction in effectiveness of the gassing device caused by temperature and pressure fluctuation which can arise during transportation and distribution, and that the end product appearance and taste should be independent of the procedure used by the consumer to open and pour the packaged beverage. Some of these difficulties were overcome by the use of a secondary chamber in the form of a capsule disclosed in EP 227213A2 in which the secondary chamber is pressurised from the primary container and its contents discharged through a permanently open orifice in the side wall of the capsule into the beverage when the can is opened. Problems associated with the fitting and retention of such capsules resulted in other proposals such as described in GB 2211813A (Price) in which the secondary chamber is formed by an apertured diaphragm which divides the interior of the can into an upper larger part and a smaller lower part. It had already been proposed in EP 227213 to use an oversize can so as to provide a headspace in the can above the beverage. This not only provided space into which the creamy head could rise but also allowed for the additional volume of the capsule (or separate compartment such as proposed in GB 2211813A Price) and for the extra beverage required to compensate for any beverage trapped in the capsule of EP 227213 or the lower compartment of GB 2211813A Price. The quantity of beverage in the secondary compartment is clearly minimised by inverting the can as has been commonplace between filling and pasteurisation since the introduction of the two-piece can following the published recommendation of the UK can manufacturer concerned as early as 1981. This inversion causes the orifice in the secondary compartment to communicate with the gaseous headspace, as described in GB 2211813A Price. Whilst the Price design allows all the beverage to drain from the secondary chamber, this is only achieved if the can is not only inverted during processing but is then left inverted until just before being opened. Price suggested that to this end the can should be printed 'upside down' so that there would be a chance that the purchaser would place the cans in their inverted state whilst awaiting use. However, there was no guarantee that the cans would be so stored, in which event the lower compartment would be filled with beverage. Although this would be under pressure and would jet through the aperture or apertures in the diaphragm of Price when the can was opened to atmospheric pressure, the results of such jetting of beverage did not result in any useful head formation and unlike the capsule of EP 227213A2 the diaphragm of Price could not allow a pocket of gas to be trapped to be discharged instead of (or as well as) some of the beverage. It can only be concluded that the Price proposal was not taken up since it could not be guaranteed that the consumer would store the can upside down and invert sufficiently quickly before opening, to prevent any of the beverage from transferring below the diaphragm. Additionally there was no significant advantage to the manufacturer since the canning of the product still had to provide excess beverage over and above what the can was stated to contain in case the can was not stored the correct way up and thereby trapped beverage below the diaphragm. EP 360375A1 describes a further development which combines the advantage of the capsule of EP 227213A (in the gas can be trapped by the device when the can is upright) with the Price proposal for a diaphragm (so as to avoid the capsule fitting and retention problems). Clearly there will always be a charge of gas trapped below the domed diaphragm of EP 360375A1 which can be maximised (and the volume of beverage minimised) if the can is inverted and left so inverted as taught by Price. EP 360375A1 described an alternative method of constructing a domed diaphragm and an alternative filling process in which the can is filled upside down, to ensure the compartment will be filled with gas before the can is turned over to stand on its base with the domed compartment at the bottom. Since the Specification envisages dosing with liquid nitrogen the pressure of the gas in the section of the can between the lid and the domed diaphragm will be greater than atmospheric very shortly after the can is sealed and this will ensure that a good charge of high pressure gas is available below the domed diaphragm when the can is subsequently inverted. However, as shown in the drawings of EP 360373, there is still a tendency for beverage to displace some of the gas at least up to the level of the aperture. As a consequence although the high pressure gas trapped below the dome will be jetted into the beverage (together possibly with some of the beverage) so as to form the desired head when dispensed, the beverage below the aperture will remain in the base of the can in the same way as it remains below the level of the aperture in the capsule of EP 227213. The trapped beverage represents lost revenue which can be significant in the case of alcoholic beverages, particularly ii tax is levied on the volume of beverage poured into the can rather than on the volume which can be poured out. The loss of revenue can be mitigated in two ways: 1. reduce the cost of the gas-storing head-producing device and the cost of inserting it into the can, and or 2. reduce the volume of beverage which can be trapped within the gas producing device. PCT/GB90/01806 (Whitbread) addresses the second option by proposing a sealed gas containing device into which beverage cannot ingress and which only opens to communicate with the beverage after the can has been opened and depressurised, so that there should be no reverse transfer of beverage into the capsule as gas leaves it. However the cost of production of such devices is not inconsiderable and the complexity of the pressure sensitive mechanism of the device to release the gas only when the can is opened, means that in practice there has been a relatively high failure rate, resulting in poor or even no head formation on beer dispensed from faulty cans. EP 520646A1 describes a modified construction of the type of capsule described in EP 227213 which is also charged with gas from the headspace following headspace transfer by means of can inversion, as described in UK 2211813 Price. The design of the capsule allows any beverage which has entered the capsule to be collected below the level of the aperture, so there is little tendency for it to be ejected ahead of or instead of the gas, provided the can is opened whilst upright. In this respect the device has the same advantage as the Price design, in that as with the Price device, no energy is wasted in ejecting beverage into the contents of the can, and it is gas only which is ejected. It is suggested that the ingress of beverage into the capsule of EP 520646A1 can be reduced by inverting the can as quickly as possible after filling but this seems to be nothing more than a restatement of the Price technique, in which, if the can is inverted immediately after filling and sealing, no beverage will have entered the lower chamber of Price, and in any event it has been commonplace to invert filled cans on canning lines within a few seconds of the final seaming of the can, for the reasons already mentioned. The design of the capsule in EP 520646A1 is in many ways also similar to that shown in GB 1266351 in that the orifice by which the secondary chamber communicates with the rest of the can points downwardly towards the base of the can, so that an air/liquid lock is formed and there will be little tendency for beverage to displace any of the trapped gas, unless the can is tilted. The side tube design of GB 1266351 may of course include a small volume of beverage if there is a liquid exchange as during pasteurisation, or thermal cycling of the can during storage, and in this respect the capsule of EP 529646A1 is better than that of GB 1266351 in that there is no slug of beverage to force out ahead of the gas charge. However the EP 520646A1 capsule suffers from a further problem in that, if as is likely to occur, some beverage does enter the capsule, since if the can is tilted with the orifice is on the underside of the capsule, any beverage trapped in the capsule will tend to occupy the position such as shown in Figure 2 of EP 520646A1, except that in this case the beverage will now overlie the orifice 12, which in Figure 2 is conveniently shown remote from the pool of liquid. Clearly if the liquid within the capsule does cover the orifice 10, the claimed advantage of an initial jetting of gas will be lost and because of the variableness of the volume of liquid in the capsule and the possibility that quite a large volume of liquid must be expelled from the capsule before the gas can escape, energy in the gas stored in the capsule will be lost as the liquid is expelled. The capsule design of EP 520646A1 does not therefore solve the problems identified above regarding variability in the volume of retained beverage in the capsule and variability introduced into the gas jetting characteristic if a significant quantity of beverage occupies the interior of the capsule and can cover the exit orifice during pouring. It is an object of the present invention to provide a method by which gas jetting capsules can be fitted into a can having a reduced diameter neck. Summary of the invention According to the present invention there is provided a method of inserting a gas-jetting capsule into a generally cylindrical beverage can having a reduced diameter neck, wherein the capsule comprises a central chamber for containing gas and having an orifice through which gas is emittable as a fine jet, characterised by the steps of providing a resiliently deformable bounding ring which is connected by spokes to the central chamber and which when inserted into the can is a close fit within the larger internal diameter of the can, temporarily deforming the ring inwardly towards the chamber by squeezing opposite regions of the ring so as to define a generally oval shape, to permit the capsule to pass through the reduced diameter neck of the can, introducing the capsule into the can whilst so squeezed, and causing relative twisting between the can and the capsule so that the latter becomes co-axial with the can in the desired position within the can. There may be at least two spokes each longer than the radial distance between the capsule and the ring, so that each spoke extends non-radially therebetween and allows the ring to be deformed. Description of drawings The invention will now be described, by way of example only, with reference to the accompanying drawings in which: Figure 1 is a diagrammatic view of a beer can partially filled with beer and containing a secondary chamber; Figure 2 shows the can of Figure 1 inverted and indicates how the headspace transfers to the opposite end of the can and communicates with the interior of the secondary chamber; Figure 3 is a perspective diagrammatic view of the secondary chamber fitted at the lower end of the can of Figure 1; Figures 4(a) and 4(b) are perspective views of an alternative chamber in which the conical part of the housing is hemispherical; Figure 5 is a cross-section through another form of secondary chamber construction; Figure 6 is an exploded perspective view of a chamber design in which the passage means is integrally formed with the side wall of the chamber; Figures 7 to 11 show how a capsule such as shown in any one of Figures 3 to 6 can be inserted into a can; and Figure 12 is a cross-sectional view through the lower end of a can containing a particularly preferred form of capsule embodying the invention. The method according to the invention may be applied to preformed (typically moulded plastics) capsules such as have been fitted to certain canned beers and stouts which conventionally are supplied in two piece spun aluminium cans in which the lid is seamed to the top of the can after filling. In Figures 1 and 2 a spun aluminium can 20 having a domed base 22 and a cover 24 seamed thereto by a seam weld 26 is filled with beer or stout or other carbonated alcoholic beverages 28 to a level 30 leaving a head space 32 thereabove which contains gas. In known manner the upper head space is pressurised during the filling process for example by liquid nitrogen dosing so that when sealed, a pressure in excess of atmospheric pressure exists within the can typically of the order of 4 bar. Situated and secured in position at the base of the can is a hollow insert 34 surrounded by a bounding ring 36 which is an interference fit within the can. The hollow insert is partly cylindrical and tapers in a conical form on its underside. A shoulder is formed within the conical surface at 38 within which is formed a very small orifice 40 which communicates with the interior of the insert in accordance with the invention in a manner which will be described later. After sealing and before pasteurisation the can is inverted so that the seam 26 can be checked for leaks as is commonplace on conventional canning lines. During pasteurisation the pressure in the can becomes greater due to the rise in temperature, and because the headspace 32 has now transferred to the other end of the can due to inversion, it is the headspace which is in communication with the interior of the insert 34 through the orifice 40 and not the liquid contents 28. During pasteurisation the overpressure produced drives gas into the insert 34 to maintain a pressure balance and provided the can is left inverted for a reasonable period of time whilst the product cools (as is normal on conventional canning lines), the consequent reduction in pressure merely causes transfer of gas out of the insert which will otherwise remain largely filled with gas and not liquid. Once the can has been cooled to room temperature it can be rotated again to stand on its base 22 for packaging and storage. Although the position of the insert will now be as shown in Figure 1 once again, and is submerged below the liquid 28, there is little tendency for liquid to enter the insert 34, but even if any liquid does enter, provision is made in accordance with the invention to restrict and prevent the intruding liquid from interfering with the function of the device which is to jet gas on opening the package, to produce a froth head on the beverage as it is dispensed. Figure 3 merely shows in more detail how the insert can be supported within the can at the lower end thereof and the same reference numerals have been used to denote the same parts as shown in the various drawings. The additional element shown in Figure 3 is the lid 42 shown fitted to the upper end of the cylindrical section of the insert 34 and the non-radial spokes 44, 46 and 48 which support the insert within the bounding ring 36. Figure 4(a) and 4(b) illustrate an alternatively shaped insert in which the lower section is more hemispherical than conical, and a shoulder is formed by cutting away part of the surface of the domed wall 50 to define a shoulder 52 in which is located the orifice 54 (denoted as 40 in Figure 1) Although the external shape of the insert shown in Figures 4(a) and (b) is different from that in Figures 1 and 2, it is to be understood that the formation of the shoulder and the provision of the orifice therein does not alter the function or operational characteristics of the device. The other feature shown in Figure 4(a) and (b) is the flexible nature of the bounding ring which is shown collapsed inwardly (as by squeezing) at two diametrically opposite regions to form a generally ovaloid shape to permit the structure to be inserted edgewise into the narrow neck of a can such as is shown in Figure 1. Once inside the can, rotation of the can relative to the insert will enable the bounding ring to interferingly engage the interior surface of the can and wedge the insert in position, and/or allows the structure to be pushed axially down the can to its desired position therein. Figure 5 is a cross-section which shows one position for the orifice 40 and the provision of an upstanding standpipe 56 which communicates between the interior of the insert and the orifice 40. Although it is not expected that much beer will ingress into the insert, for illustration a considerable quantity of beer is shown in the insert 34 and the surface is denoted by reference numeral 58. It will be seen that provided the standpipe extends near to the top of the chamber as shown, the can 20 may be tilted for in excess of the angle which the can would normally adopt when pouring therefrom, before there is any tendency for the beer or other liquid in the device to cover the upper end of the standpipe 56 and thereby cause liquid to be ejected in preference to gas. The gas trapped in the head space 60 is thus free to exit through the pipe and orifice 40 when the can is depressurised as when broached before dispensing its contents, and a good foaming froth head is produced by the emission of a stream of bubbles from the orifice in known manner. An alternative position for the standpipe is shown at Figure 6 in which a radially inwardly directed protrusion 62 accommodates the fluid passage. Although not shown in both arrangements of Figures 5 and 6, the upper end of the standpipe or passage can be extended laterally so as to communicate with the centre line of the insert if desired. The advantage of doing this is that the upper end of the passage 56, 62 is thereby located approximately on the centreline of the can 20, and thus renders the device substantially insensitive to can orientation when pouring. A disadvantage is that this increases the volume of the standpipe and in the event the liquid is trapped in the standpipe an increased volume of liquid has to be ejected from the standpipe before the gas can escape. Where the bounding ring is such as shown in Figures 3 and 6 the insert cannot be so easily inserted into a can having a reduced diameter neck, and Figures 7 to 11 show a method in accordance with the invention by which such an insert can in fact be located within a can. To begin with, the insert is located on an upstanding pedestal 68 with the conical or domed section of the insert pointing upwards. As shown in Figure 8, the can 70 is then lowered at an angle over the insert and because the bounding ring 26 is presented to the can at a relatively sharp angle, the reduced diameter neck region of the can 70 will tend to squeeze the ring inwardly and deform the ring to enable it to enter through the reduced diameter section of the can. Once beyond the neck denoted by 72, the angle of the can 70 to the support 68 is maintained substantially constant whilst the can is lowered, thereby presenting an effectively larger area to the ring 26 than would be the case if the can were aligned with the axis of the support 68 before it is lowered. This is shown in Figure 9. Once the insert has been pushed into contact with the domed end 74 of the can 70, the can can be titled into alignment with the axis of the support 68. The insert will now be in the correct position and alignment within the can. By providing a releasable gripping device 76 at the upper end of the support 68, the insert can be released by operation of the release mechanism enabling the can together with the insert positioned therein to be withdrawn off the support 68 in an upward direction as shown in Figure 11. The support is now ready for another insert to be positioned thereon and a further can lowered thereover in a similar manner to that illustrated in Figures 7 to 10. It is of course necessary for the head 76 of the support to have a diameter which is a clearance fit or better within the reduced diameter neck region 72 of the can 70. A further advantage of a can fitted with an insert as described herein is that should beverage ingress, the insert can be in fact substantially emptied of unwanted beverage by subjecting the pressurised and filled can or bottle to temperature cycles whilst in an inverted position, so that the insert communicates with the gaseous head space. Such temperature and pressure cycling does not have to be carried out at the same time as pasteurisation or immediately after filling and seaming but can be performed at any time provided the can is intact. A preferred form of capsule construction is shown in Figure 12. The capsule is denoted by reference numeral 78, the standpipe by 80, the lid by 82, the downwardly projecting protrusion 84 and the orifice at 86. The capsule is shown fitted in a can 88 by fingers or spokes 90 and a bounding ring 92 which engages the interior of the can and holds the device in position at the bottom of the can with the spigot 84 touching the domed base of the can. The spokes may be as shown in Figures 3 to 6. The capsule operates substantially as described in relation to Figures 1 to 6 except that the gas jetting from the device now leaves substantially horizontally and thus creates a good swirling action in the can. The domed lid 84 is optional, but if provided enables a larger volume of gas to be trapped above the standpipe 80 even if the capsule becomes filled with beer to the level of the latter, as may happen if the can is not turned over for a long time after the can has been pressurised during the canning process. This makes the position and therefore timing of the twist to invert the cans as is provided on conventional canning lines, less critical, and may allow lines to be used without modification since although some canning lines have the post filling twist positioned so that the cans are inverted within 3 seconds of filling, others do not do so until some 10 seconds or more after filling. If the sealed can is thermally cycled as between normal house temperature and the temperature of a domestic refrigerator, with the can in its normal upright position, there may be a further liquid-gas exchange such that more liquid is left in the capsule. Since the liquid trapped in the capsule reduces the volume of the capsule available for gas and since it is the latter which creates the desirable froth head, it is advantageous if the quantity of beer entering the capsule is constant so that a consistent head producing effect is obtained. The provision of an internal passage or standpipe in the capsule to act as a liquid trap, prevents any beverage trapped in the capsule from leaving it. However these devices do not prevent a variation in the proportions of liquid to gas in the pod when the latter is charged at least in part by gas, due to the inversion of the cans on the filling line.

Claims: A method of inserting a gas-jetting capsule into a generally cylindrical beverage can (20) having a reduced diameter neck, wherein the capsule comprises a central chamber for containing gas and having an orifice (62) through which gas is emittable as a fine jet, characterised by the steps of providing a resiliently deformable bounding ring (46, 92) which is connected by spokes (44, 90) to the central chamber and which when inserted into the can is a close fit within the larger internal diameter of the can, temporarily deforming the ring inwardly towards the chamber by squeezing opposite regions of the ring so as to define a generally oval shape, to permit the capsule to pass through the reduced diameter neck of the can, introducing the capsule into the can whilst so squeezed, and causing relative twisting between the can and the capsule so that the latter becomes co-axial with the can in the desired position within the can. A method as claimed in claim 1 wherein the capsule is pushed along the can towards the base thereof after the squeezing force has been released. A method as claimed in claim 1 or claim 2 in which there are at least two spokes (44; 90) each longer than the radial distance between the capsule and the ring, so that each spoke extends non-radially therebetween and allows the ring to be deformed.

Inventors: CONWAY JOHN KELSHAW, FRESHWATER STEPHEN MICHAEL, POLEY JOHN, REYNOLDS ANDREW JOHN, SKINGSLEY JOHN DAVID, CONWAY, JOHN KELSHAW, FRESHWATER,STEPHEN MICHAEL, POLEY, JOHN, REYNOLDS, ANDREW JOHN, SKINGSLEY, JOHN DAVID
Applicants: SCOTTISH & NEWCASTLE PLC
Application year: 1993
Main classification: B65D79
IPC codes: B65D79, B65D85