Carbonated beverage container

Abstract: When dispensing carbonated beverages, particularly beers, it is desirable to obtain a close-knit creamy head. To achieve this a container (1) includes a separate closed hollow insert (5) containing substantially no oxidising gas and means (6) responsive to opening of the container (1) to provide communication between the inside of the insert (5) and beverage (7) contained in the body of the container (1) upon opening it to jet gas from the insert (5) into the beverage (7). The means (6) preferably has the form of a pressure responsive valve. The insert (5) may be arranged so that its internal pressure is increased after the container (1) is sealed. The insert (5) may float on the surface of the beverage (7).

Description: When dispensing carbonated beverages, particularly beers and especially draught stout, it is desirable to obtain a close-knit creamy head. This contributes to a creamy taste and adds considerably to the customer appeal. Traditionally such heads are only obtained when dispensing such beverages from draught. Another factor that considerably enhances the appeal is the way in which, when dispensing beverages, especially beers, from draught, small bubbles are intimately mixed with the body of the beverage as it is dispensed and then, after dispensing is completed they gradually separate out to form this close-knit creamy head. The formation of such small bubbles liberated throughout the body of the beverage during dispensing can be encouraged by causing shear of the liquid with resulting local pressure changes which causes release of small bubbles of controlled and uniform size. Over the years many proposals have been made to increase and control the liberation of such small bubbles and the generation of heads on beverages. Our own earlier specification GB-A-1,378,692 describes the use of an ultrasonic transducer to subject the beverage to shear immediately before it is dispensed into a drinking vessel and describes the way that by subjecting the initially dispensed portion of beverage to ultrasonics the small bubbles released from this initial portion then gradually float up through the remainder of the beverage forming nucleation sites and triggering the generation of further small bubbles of controlled size. There have been many other proposals such as those described in GB-A-1,280,240, GB-A-1,588,624 and GB-A-2,200,854 to encourage the formation of the required close-knit creamy head on beers and other carbonated beverages. However, most of these proposals are concerned with the formation of a head as a beer is dispensed from draught. GB-A-1,266,351 describes a system for producing a draught type head when dispensing beer, or other carbonated beverage, from a container such as a can or bottle. In the arrangement described in this specification, the container includes an inner secondary chamber which is charged with gas under pressure either as part of the filling process in which the container is filled with beverage or by pre-charging the inner secondary chamber with gas under pressure and sealing it with a soluble plug made from a material such as gelatine which, dissolves shortly after filling. The secondary chamber includes a small orifice and the overall arrangement is such that, upon opening the container and so reducing the pressure in the main body of the container, gas from the secondary chamber is jetted via the orifice into the beer in the main body of the container so causing shear and liberating the required small bubbles which in turn act as nucleation sites to trigger release of similar bubbles throughout the entire contents in the can or other container. The arrangements described in this patent specification are somewhat complex mainly requiring the use of a separate charging step to pressurize the secondary chamber and a specially designed divided can with the result that this technique has not been adopted commercially. GB-A-2,183,592 describes a different technique which has recently achieved success in the market place. In this system a container of a carbonated beverage includes a separate hollow insert with an orifice in its side wall. As part of the container filling process beer is deliberately introduced into the inside of the hollow insert through the orifice and the pressures of the inside of the insert and the main body of the container are in equilibrium. Upon opening the container the beverage from inside the insert is jetted out through the orifice into the beverage in the body of the container and this jet acts to shear liquid in the container with the result that a number of small bubbles are liberated which, in turn, act as nucleation sites to generate a number of small bubbles throughout the entire contents of the container. When dispensing a beverage from such a container into a drinking vessel the liberation of small bubbles throughout the entire volume of the beverage as it is dispensed gives a similar appearance to dispensing the same beverage from draught. This system has many disadvantages. It is essential to remove oxygen from inside the hollow insert before filling the container with beverage. The presence of oxygen inside the container leads to the beverage being oxidised with a resulting impairment of flavour and risk of microbial growth leading to, for example, acetification of the resulting beverage when it contains alcohol. Thus, there is a general requirement to displace substantially all of the oxygen from a container, and its secondary chamber, when this is used, before the container is sealed. When the secondary chamber has the form of a hollow insert with only a small orifice in its wall and this insert is filled with air it is difficult to displace all of the air during the filling and sealing of such a container. As a way of overcoming this problem GB-A-2,183,592 describes manufacturing such a secondary chamber by a blow moulding technique using an inert gas to form the secondary chamber and then only forming the orifice as the secondary chamber is placed into the container, for example by irradiation with the laser beam. However, in practice, this is not the way that such containers are filled. In practice, the secondary chamber is injection moulded in two halves, which are subsequently welded together. As it is formed, the normal atmospheric gases fill the secondary chamber. Such a secondary chamber is then inserted into an empty container and the whole is subjected to a reduced pressure, filled with a non-oxidising gas such as carbon dioxide, nitrogen, or a mixture of these, and evacuated again to flush substantially all of the oxygen from both the inside of the container and the inside of the secondary chamber before the container is again filled with a non-oxidising gas and only after that filled with beverage. In this way the amount of oxygen remaining in the sealed container is reduced to an acceptable level but these additional evacuation and flushing steps add a considerable delay and difficulty to the container filling stage with the result that the speed of filling is reduced to about 25 per cent of that of an equivalent system in which a secondary chamber is not included in the container. Also, since they require the use of a special, non-conventional filling machine this also imposes a considerable capital cost burden. According to a first aspect of this invention, a sealed container includes a beverage and a separate hollow insert, the insert containing a non-oxidising gas characterised by the insert being arranged to reduce its internal volume after sealing the container to contain the gas at a super-atmospheric pressure, the insert including means responsive to opening of the container to provide communication between the inside of the insert and the beverage so that on opening of the container the insert which is closed apart from the means jets gas via the means into the beverage. According to a second aspect of this invention, a method of filling a container includes the steps of: providing a container and a separate closed hollow insert containing a non-oxidising gas at substantially atmospheric pressure, filling the container with beverage and sealing it, and causing the volume of the hollow insert to change to build up the pressure inside the insert to a super atmospheric pressure, the insert including means responsive to the opening of the container so that when the sealed container is opened the super atmospheric pressure inside the insert jets gas from the insert into the beverage in the container. When the insert changes its volume as a result of the increase in pressure that builds up in the container after it is filled and sealed the insert may be arranged to collapse or concertina and include a mechanical lock so that, once collapsed or concertinaed, the insert is then held into its collapsed or concertinaed condition irrespective of subsequent changes in pressure inside the container. On collapsing the pressure inside the insert increases considerably as a result of the reduction in the volume of the insert and, since the insert is locked into its collapsed state, it then holds gas at a much higher pressure than when first inserted into the container. One way in which the insert can be shaped so that it collapses is for it to include one or more domed faces which, upon application of a pressure evert into a stable state. Another way in which the insert can be made to contract and compress gas contained within it is to manufacture the insert from bi-axially stretched plastics material. Such material is bi-axially stretched whilst hot and then cooled to lock it into its bi-axially stretched orientation. However, as soon as such material is subsequently heated its plastic memory causes it to shrink. Thus, the insert may be made from a bi-axially oriented material such as bi-axially oriented polyethylene terephthalate (PET) and filled with gas substantially at atmospheric pressure. Then on pasteurisation of the filled containers the insert shrinks considerably in volume so compressing the gas within the insert substantially to the pressure subsisting within the container. As the container and its contents cool the insert is again locked into shape. The insert may be arranged to float on the beverage and in this case the insert is weighted and includes means responsive to opening of the container to provide communication between the inside of the insert and the beverage so that on opening of the container the insert which is closed apart from the means jets gas via the means into the beverage. Upon opening the sealed container the means opens to inject gas from the hollow insert into the beverage in the container to cause shearing of the beverage in the container and liberation of small bubbles throughout the contents of the container. When the insert floats in the liquid in the container it is weighted so that the part from which gas is jetted on opening the container is always arranged towards the base of the insert. The means may have the form of a burst disk which, upon subjecting the burst disk to the pressure differential between that subsisting in the inside of the insert and atmospheric pressure subsisting in the container after it is opened, bursts the burst disk to provide an aperture through which the gas is injected into the beverage in the container. The means may alternatively have the form of a manually openable valve or puncturing device connected to the container closure so that, upon opening the container the opening operation also opens the valve or punctures the insert to release the non-oxidising gas from the insert into the beverage in the container. The means may have the form of a pressure responsive valve means which, when exposed to the pressure difference subsisting between the gas inside the insert and the atmospheric pressure subsisting in the container after opening, opens to jet gas into the beverage in the body of the container. One form of the valve means consists of a bore terminating in a restricted orifice and a plug on the outside of the insert which fits inside the bore and which, when subjected to the pressure differential created on opening the container is blown out of the bore to provide jetting of the gas into the beverage via the restricted orifice. In this case preferably the plug is a captive plug moulded integrally with the material surrounding the bore and orifice. Another type of valve means includes a cap which can be blown off or slide axially to expose at least one orifice in the wall of the insert or in the cap. This type of valve means is arranged so that, the cap is subjected to the pressure difference subsisting between the inside and outside of the insert and this acts to open the cap to expose the at least one orifice and thereby allow gas to be vented via the at least one orifice into the beverage in the container. In a further, preferred arrangement the valve means may have the form of a pressure responsive member which is exposed to any pressure difference between the inside of the insert and the inside of the container and which moves or distorts to open an aperture to allow escape of gas from inside the insert into the beverage in the container. One form of this valve means comprises a captive resilient bung inserted through an aperture in the wall of the insert which, when subjected to a sufficient pressure differential, flexes to allow gas to be vented from inside the insert through the opening into the beverage in the body of the container. Another form of this type of valve means comprises a seating surrounding the inside of an orifice and a valve closure member which seats against and forms a seal with the seating. Preferably the insert includes two opposed faces with the orifice and seating formed on one face and the valve closure member attached to the inside of the other face and extending to the seating on the inside of the one face. By forming the insert from slightly resilient material such as a plastics material at least one of the opposed faces flexes outwards as a result of pressure differences between the inside and outside of the insert after the container is opened. Such flexing of the face causes relative movement between the seating and the valve closure member to unseat the closure member to allow gas from inside the insert to pass between the seating and valve closure and to be emitted through the orifice into the beverage in the body of the container. It is preferred that the insert is pre-charged with a non-oxygen containing gas such as carbon dioxide, nitrogen, or a mixture of these during manufacture. The insert is preferably pre-charged to a super atmospheric pressure, however, it is also possible for it to be partially evacuated or, only to be filled with non-oxygen containing gas at substantially atmospheric pressure when initially inserted into the container. When the insert is pre-charged to a super atmospheric pressure it may be held under this super atmospheric pressure whilst it is inserted into the container and the entire container and insert held under this super atmospheric pressure whilst it is filled. However, this is not preferred since it requires the use of non-conventional equipment. What is preferred is for the insert having been pre-charged with non-oxidising gas to be stable and completely closed when exposed to the atmosphere before being inserted into the container. One way in which this is achieved is by having the insert filled with non-oxidising gas at substantially atmospheric pressure and for the pressure inside the insert to be built-up after the insert is placed in the container and the container filled with beverage. Preferably the insert is formed in two parts, a main body portion and a separate lid. In this way, during manufacture and assembly of the insert the body can be pre-charged easily. The insert may be pre-charged by closing the lid and the main body portion whilst subjecting the insert to a non-oxidising gas atmosphere at normal or super atmospheric pressure or, alternatively, the insert may have an inert gas such as liquid or solid carbon dioxide, liquid nitrogen or a mixture of these placed into the main body portion and then, after a brief delay to allow some of the liquid or solid gas to vaporise and displace air from the body of the insert the lid is fitted onto the body to close the insert. As the remaining solid or liquid inert gas vaporises it pre-charges the insert to a super atmospheric pressure. The amount of solid or liquid inert gas introduced into the insert is preferably metered to provide the required pressure. Conveniently this pre-charging of the inserts is carried out by having the body portions fed on a conveyor past a liquid inert gas metering nozzle which dispenses a metered quantity of liquid inert gas into each insert body in turn. The insert bodies are then carried by the conveyor to a capping station at which the lids are fitted. The separation between the liquid gas metering nozzle and the capping station and the speed of the conveyor are chosen to provide the time delay required to displace air from the body. The lid is preferably a simple snap-fit on the body but, alternatively it may be connected by a screw-thread, by welding or by an adhesive, for example. The insert in accordance with the other and further aspects of this invention may be an interference fit with the side wall of the container so that it is held in position. When the container is formed by a can the can may be locally deformed to trap such inserts at a particular location. In a further version portions of such inserts may be placed between a side wall of the container and its lid so that the insert is held captive once the lid is fixed on the container. With the arrangements in accordance with this invention the insert is always closed when it is inserted into the container and thus, the container requires no additional flushing and purging steps other than those required for a conventional container filling operation. Thus, the present invention has considerable advantages over the commercially operated version of the system described in GB-A-2,183,592 and yet still uses standard containers such as standard metal cans or plastics or glass bottles and the containers can be handled by standard container filling machinery once the inserts have initially been loaded into the containers. Other aspects of the examples described in the following examples are also described and claimed in the parent application published as EP-A-0,502,059. Particular examples of containers and methods in accordance with this invention will now be described with reference in particular to Figs 31 to 41 of the accompanying drawings. The examples illustrated in Figs. 1 to 31 do not fall within the scope of the present invention, but Figures 1 to 4 illustrate examples of ways in which inserts, including those of the present invention, may be provided in a container, and Figures 5 to 31 illustrate examples of closure means which may be used with inserts, including those of the present invention. Figure 1 is a cross-section through a first example of can containing an insert; Figure 2 is a cross-section through a second example of can containing an insert; Figure 3 is a cross-section through a third example of can containing an insert; Figure 4 is a cross-section through a fourth example; Figure 5 is a scrap cross-section of a first example of closure means; Figure 6 is a cross-section through an insert having a second example of closure means in a first condition; Figure 7 is a plan through the insert shown in Figure 6; Figure 8 is a cross-section through the insert shown in Figure 6 in a second condition; Figure 9 is a scrap cross-section through a third example of closure means in a first condition; Figure 10 is a scrap cross-section through the third example of closure means in a second condition; Figure 11 is a cross-section through an insert with a fourth example of closure means; Figures 12 and 13 are a cross-section and plan respectively of a main body portion of the insert shown in Figure 11; Figures 14 and 15 are a cross-section and plan respectively of a first cap of the insert shown in Figure 11; Figures 16 and 17 are a cross-section and plan respectively of a secondary cap of the insert shown in Figure 11; Figure 18 is an exploded cross-section through an insert with a fifth example of closure means; Figure 19 is a cross-section through the assembled insert shown in Figure 18 in a first condition; Figure 20 is a cross-section through an assembled insert shown in Figure 18 in a second condition; Figure 21 is a cross-section through an insert including a sixth example of closure means in a first condition; Figure 22 is a cross-section through the insert shown in Figure 21 in a second condition; Figure 23 is a scrap cross-section through a seventh example of closure means; Figure 24 is an under plan of the seventh example of closure means; Figure 25 is a scrap cross-section through an eighth example of closure means in a first condition; Figure 26 is a scrap cross-section through the eighth example of closure means in a second condition; Figure 27 is a scrap cross-section through a ninth example of closure means; Figure 28 is a scrap cross-section through a tenth example of closure means; Figure 29 is a plan of the closure means shown in Figure 28; Figure 30 is a cross-section through an insert including an eleventh example of closure means; Figure 31 is a cross-section through an insert including a twelfth example of closure means; Figure 32 is a cross-section through a thirteenth example of closure means in a first condition; Figure 33 is a cross-section through the thirteenth example of closure means in a second condition; Figure 34 is a cross-section of the thirteenth example of closure means in a third condition; Figure 35 is a scrap cross-section drawn to an enlarged scale of the thirteenth example of closure means; Figure 36 is a cross-section through an insert prior to its internal pressure being increased; Figure 37 is a cross-section through the insert shown in Figure 36 after its internal pressure is increased; Figure 38 is a cross-section through another example of insert prior to its internal pressure being increased; Figure 39 is a cross-section through the insert shown in Figure 38 after its internal pressure is increased; Figure 40 is a cross-section through a further example of insert before pasteurisation and prior to its internal pressure being increased; and, Figure 41 is a cross-section through the insert shown in Figure 40 after pasteurisation and after its internal pressure is increased. In all these examples the container has the form of a can 1 with a lid 2 including a non-resealable closure 3 such as a tear-off ring pull or a stay-on tab. The lid 2 is joined onto the upper rim of the can 1 by a folded seam 4. The can 1 also contains a hollow insert 5 having a volume typically between 5 and 20 ml which is filled with carbon dioxide, or nitrogen or a mixture of these and which has one of a variety of forms to be described in detail subsequently. The inserts shown in Figures 1 to 4 are not arranged to reduce their internal volume, and therefore do not fall within the scope of the present invention, but merely illustrate examples of ways in which inserts, including those of the present invention, may be provided in a container. All include some closure means 6 through which gas from the insert 5 is vented. The inserts shown in Figures 5 to 31 are not arranged to reduce their internal volume, and therefore do not fall within the scope of the present invention, but merely illustrate examples of closure means which may be used with inserts, including those of the present invention, to respond to the opening of the container for providing communication between the inside of the insert and the beverage in the container. The can 1 is also filled with a beverage 7 such as a beer. Whilst the non-resealable closure 3 is closed the hollow insert 5 contains only gas and the closure means 6 is closed so that the beverage 7 inside the can 1 is prevented from entering the hollow insert 5. However, upon opening the non-resealable closure 3 the pressure inside the can 1 is reduced to atmospheric, whereupon the super atmospheric pressure of the gas inside the hollow insert 5 causes gas to be vented through the closure means 6 to provide a jet of gas into the beverage 7. The jet of gas causes shear in the beverage 7 with a resulting liberation of a number of small bubbles which, as they rise through the beverage 7 in the can 1, form nucleation sites which trigger the liberation of further small bubbles throughout the beverage 7. Thus, as the beverage 7 is poured out of the can 1 and into a receptacle such as a drinking glass the bubbles are intimately mixed with the beverage and give the appearance of dispensing the beverage from draught. Whilst the closure means 6 is shown located in the top of the insert 5 in Figure 1 it may also be located in the base as shown at 6' or at the side of the insert 5. The hollow insert 5 may include arms 8 with flanges 9 which are an interference fit on the internal side wall of the can 1 as shown in Figure 1 to hold the insert 5 in position inside the can 1. The side wall of the can 1 may include internal protrusions to help retain the insert 5. Alternatively, as shown in Figure 2, the insert 5 may float in the beverage 7 and include a weight 10 so that it is always oriented in a particular direction inside the can 1 so that, on opening the can 1 gas is jetted from the closure means 6 into the beverage 7. In a third example shown in Figure 3 the insert 5 includes flexible arms 11 which again engage the inner side wall of the can 1 to hold the insert 5 in position. Again the side wall of the can 1 may include internal protrusions to help retain the insert 5. In another example shown in Figure 4 the side wall 1 of the can is deformed after insertion of the insert by forming radially inwardly projecting protrusions 12 which hold the insert 5 in position adjacent the base of the can 1. As further options, not illustrated, the insert may be glued in position on the inside of a can 1, be held against the side wall or base of the can 1 by including, or being formed as a "sucker" or, alternatively, flange 8 of the insert 5 may be trapped in the seam 4 between the lid 2 and the can 1 as described in EP-A-0,481,019. Various different closure means 6 will now be described. All are generally usable with any of the above forms of insert 5. All react to a pressure differential between the inside of a hollow insert 5 and the inside of a can 1 by opening to allow the super atmospheric pressure inside the insert 5 to jet gas from inside the insert 5 into the beverage 7 in the container 1. The first example of closure means 6 provides a small burst disk 15, as shown in Figure 5 formed in the wall of the insert 5. In this example the wall of the insert 5 contains a small area of very thin section 15 and this thin section bursts at a pressure differential of, for example, 1.3 Bar to provide an aperture of about 0.1 mm diameter. A support may be provided on the inside of the insert 5 to prevent the disk 15 bursting inwards, for example during pasteurisation. The second example of closure means, shown in Figures 6, 7 and 8 comprises a cup-shaped insert 16. This is filled with gas and closed and sealed by a thin membrane 17 of aluminium or plastics film. The membrane 17 is typically heat sealed or glued to a flange 18. A rounded upper rim 19 of the cup-shaped insert 16 has a cap 20 snap fitted onto it. The cap 20 includes apertures 21 and a downwardly projecting spike 22 which initially rests lightly on the surface of the membrane 17. After insertion in the can 1 the pressure inside the insert builds up as will be described in detail subsequently until it is in substantial equilibrium with the pressure inside the can 1. Provided the pressure inside and outside is substantially the same then the membrane 17 remains generally planar as shown in Figure 6. Upon opening the ring-pull 3 however the pressure inside the insert 5 is very much greater than that of the atmosphere and accordingly the membrane 17 bows outwards and ruptures against the spike 22 so that gas is jetted from the insert 5 into the beverage 7 in the can 1. In a third example the closure means 6 are formed by an aperture 25 of small diameter such as 0.3 mm leading in to an aperture 26 of larger diameter such as 10 mm. A captive plug 27 connected to the side wall of the insert by a strap 28 is initially inserted into the bore 26 completely to close the aperture 25 and hence close the hollow insert 5 as shown in Figure 9. However, when subjected to a pressure differential greater than that required to overcome the friction between the plug 27 and the wall of the aperture 26 as a result of opening the non-resealable closure 3 in the lid 2 of the can 1 the pressure inside the insert 5 drives the plug 27 out of the aperture 26 to allow gas from inside the insert to be jetted through the fine aperture 25 as illustrated in Figure 10. A fourth example of closure means is shown in Figures 11 to 17. This example comprises a cup-shaped insert 30 with a rounded rim 31 and connected to arms 8 with a flange 9 which is an interference fit on the internal side wall of the can, and a lid 32 including an aperture 33 of small diameter. The small aperture 33 has a diameter of 0.3 mm and also includes an annular groove 34 which cooperates with the rounded rim 31 to provide the snap-fit engagement. A secondary cap 35 including a rim 36 fits around the outside of the cap 32. The rim 36 forms an interference fit with the outer diameter of the cap 32. When the insert 5 is present inside a can 1 the pressure inside the insert 5 is substantially in equilibrium with the contents of the can and the way in which it is achieved is by one of the various ways described subsequently. Upon opening the can by releasing the closure 3 a substantial pressure differential exists across the faces of the secondary cap 35 as a result of the pressure inside the insert 5 acting via the small orifice 33. This is sufficient to overcome the interference fit between the rim 36 and the outside of the cap 32 to cause the secondary cap 35 to blow off. Gas from inside the insert 5 is then jetted via the small orifice 33 causing shear in the beverage and the liberation of small bubbles throughout the beverage 7. The blowing off of the cap causes a shock wave throughout the beverage 7 which also liberates further small bubbles of gas from the beverage. The fifth example which is shown in Figures 18 and 19 is a further refinement of the fourth example. Again it comprises a cup-shaped body portion 30 with a rounded projecting rib 31 formed around the outside of its open end. In the fifth example the insert includes a single cap 37 having an in-turned rim 38 and an internal annular projection 39. A small aperture 33 is formed in the in-turned rim 38. The insert 5 is loaded with an inert gas and the cap 37 fitted on to it. The cap 37 is pushed completely on to the cup-shaped portion 30 so that the outside of the annular projection 39 forms a tight seal with the inner surface of the rim at the open end of the cup-shaped portion 30. The open rim is further supported by the rounded projection 31 engaging the in-turned rim 38 of the cap 37 which further ensures the integrity of the seal formed between these regions. When the insert 5 is subjected to a substantial pressure difference the cap 37 is driven axially away from the body 30 until the in-turned portions of the rim 38 engage the projecting rib 31. In this position the seal formed between the annular projection 39 and the open end of the portion 30 is broken so that the gas from inside the insert 5 is jetted into the beverage 7 via the small diameter orifice 33. A sixth example shown in Figures 21, 22 and 23 is somewhat similar to the fifth example except that the cup-shaped portion 30 includes an inwardly directed annular projection 40 and in that the cap 41 has a depending flange 42 with an out-turned end 43. Small diameter apertures 33 are provided in the flange 42. After the body 30 has been filled with gas the cap 41 is urged into it to close its open end and seal the insert. The cap 41 may be retained by an interference fit as in the fifth example or may be secured in position with an adhesive 44. The function of the adhesive will be described in detail subsequently. Again, the pressure inside the insert 5 is substantially the same as that in the filled can and, upon opening the can 1 the super atmospheric pressure inside the insert 5 causes the cap 41 to move outwards into the position shown in Figure 22. The gas is then vented via the apertures 33 into the beverage 7 in the can 1. A seventh example of closure means 6 is shown in Figures 23 and 24. In this example an aperture 45 in the wall of the insert 5 has a rubber or rubber-like bung 46 inserted into it to close it. The bung 46 includes an enlarged head portion 47 and a toggle portion 48 which holds the bung 46 captive in the hole 45. The head portion 47 of the bung 46 normally seals against the outer surface of the insert 5 to maintain it closed. However, when sufficient pressure differential exists between the inside of the insert 5 and the inside of the can 1 the bung 46 distorts to allow gas to leak through the hole 45 and underneath the head 47 of the bung 46 to provide a jet of gas from inside the insert 5. In the eighth example the insert 5 is formed by a generally closed circular body which may be formed in two parts. One circular face 50 of the insert 5 includes a central aperture 51. A tubular portion 52 of rubber of rubber like elastomeric material is inserted in the bore 51. The fit between the bore 51 and the tubular portion of rubber or rubber like elastomeric material 52 is arranged so that when the circular face 50 is substantially planar, as shown in Figure 25, that is when the pressure inside the insert 5 is substantially the same as that outside then the aperture through the middle of the tubular insert 52 is pinched off by the sides of the aperture 51, again as shown in Figure 25. However, when the pressure inside the insert 5 is considerably greater than that outside, the insert 5 tends to bulge so that its circular face 50 has a generally conical form as shown somewhat exaggerated in Figure 26. This reduces the pressure exerted by the sides of the aperture 51 on the insert 52 allowing a central aperture 53 in the insert 52 to open up to allow gas to be jetted through the aperture 53 into the beverage in the container 1. In the ninth example the insert 5 includes a pressure responsive valve generally similar to those used on bicycle tyres, see Figure 27. Thus, the insert 5 includes a hollow spigot 55 including a small aperture 56 of diameter 0.5 mm. A rubber or rubber like elastomeric sleeve 57 surrounds the outside of the spigot 55 and covers the small aperture 56. The sleeve acts as a valve to prevent ingress of liquid from the beverage 7 inside the can 1 via the aperture 56 but, when the pressure inside the insert 5 is greater than that outside gas is vented from inside the insert 5 through the small aperture 56 and forces the sleeve 57 away from the surface of the spigot 55 so that the gas can escape between them. The tenth example of closure means 6 is shown in Figures 28 and 29. In this example the wall of the insert 5 includes a small diameter aperture 60 leading into a chamber 61 of considerably greater diameter. The chamber 61 houses a sealing plate 62 which is retained in place by lugs 63 adjacent the open end of the chamber 61. When the pressure outside the chamber 5 is greater than that inside, the sealing plate 62 is urged against the base of the chamber so sealing the small diameter aperture 60. When the pressure inside the chamber 5 is greater than that outside, the plate 62 lifts from its seat to allow gas from inside the insert 5 to escape via the small diameter aperture 60 and around the side of the plate 62. Adhesive 64 may be provided between the plate 62 and its seat so that the plate can be adhered in position to resist an initial pressure difference between the inside of the insert 5 and the outside. Again, the function of this adhesive will be described in more detail subsequently. In the eleventh example the insert 5 comprises an open topped cup-shaped container 65 with a rounded projection 66 extending radially outwards around its open rim as shown in Figure 30. A lid 67 includes a small diameter orifice 68 surrounded on its outer surface by a generally hemispherical seating surface 69. A hemispherical sealing member 70 is urged into the hemispherical seating surface 69 by a clothes peg type spring 71 and normally seals the small diameter aperture 68. The sealing member 70, and hemispherical seating surface 69 provide a pressure responsive valve assembly with the relief pressure of the valve assembly being determined by the strength of the clothes peg type spring 71. When the pressure inside the chamber 5 exceeds the pressure differential required to lift the sealing member 70 from its seating 69 gas is vented from inside the insert 5 through the orifice 68 and into the beverage 7 in the can 1. The twelfth example is generally similar to the eleventh only, in this case, instead of having a clothes peg type spring 71, a lever 72 is provided which is formed integrally with the lid 67 and which acts as a cantilever spring to hold a sealing member 73 in place closing the small diameter orifice 68 and engaging the hemispherical seating surface 69 as shown in Figure 31. This example works in exactly the same way as the previous example. The fourteenth example is shown particularly in Figures 32 to 45. The insert 5 comprises an open ended cup-like portion 90 with a radially outwardly projecting rib 91 around its rim. A lid 92 including portions of reduced thickness 93 and a central, small diameter aperture 94 is arranged to be a snap fit on the rib 91. A valve closure member 95, which is shown most clearly in Figure 40 is held against the underside of the small diameter aperture 94 and seats against a frusto-conical surface 96. The valve closure member 95 is held in place in the lid 92 by slightly in-turned portions 97 at the end of the frusto-conical surface 96. A tubular portion 98 extends upwards as shown in Figures 32 to 35 from the base of the cup-shaped portion 90 and includes a funnel-shaped lead-in portion 99 at its upper end and ratchet teeth 100 on the inside at its upper end. The valve closure member includes a spigot 101 which extends downwards away from the valve closure member 95. The lid 92 having initial configuration shown in Figure 32 is placed on top of the portion 90 in a nitrogen atmosphere at super atmospheric pressure of around 2 Bar. The valve closure member 95 is held against its seat 96 and consequently the gas is subsequently contained and held inside the insert 5 even when it is exposed to atmospheric pressure. The insert 5 is then loaded into a can 1 which is subsequently filled with beer 7, dosed with liquid nitrogen and sealed in the conventional fashion. As the pressure inside the can 1 builds up and exceeds the 2 Bar pressure inside the insert 5 the lid 92 is urged downwards towards the base of the portion 90. Particularly during a pasteurisation step when the pressure inside the can reach 4 Bar the lid is urged further downwards towards the base of the portion 90 into position shown in Figure 34. The spigot 101 is guided by the lead-in portion 99 so that it enters the top end of the tubular portion 98 and engages with the ratchet teeth 100. After pasteurisation is complete the pressure inside the can falls somewhat but is still broadly comparable with that inside the insert 5 so that the insert remains in the condition shown in Figure 34. However, upon opening of the can 1 the pressure inside the insert 5 then is at a higher pressure than the atmospheric pressure subsisting in the can 1 with a result that the lid 92 bows upwards and outwards. However, on this occasion the valve closure member 95 is held by the inter-engagement of its spigot 101 with the ratchet teeth 100 and thus, as the lid 92 bows upwards the valve closure member 95 is removed from its seat 96 and the gas inside the insert 5 is jetted through the small diameter orifice 94 into the beverage 7 in the can 1. The pressure in the insert 5 can be built up after the insert 5 is loaded into a can for a change in the volume of the insert 5 to occur after it is placed in a can 1. Figure 36 illustrates a cross-section through a generalised two-part insert 5 with a closure means 6. The two-part insert comprises a base portion 110 and a lid 111. The lid 111 is generally domed when first fitted to the portion 110. The two parts of the insert 5 are preferably assembled in a nitrogen atmosphere at or around atmospheric pressure. The insert is then placed in a can 1 and as the can is filled with beverage 7, dosed with liquid nitrogen, and has its lid 2 sealed to it using conventional can filling machinery the pressure inside the can 1 builds up. Once it is built up to a sufficient extent it everts the lid 111 so that it is forced inwards into the insert 5 as shown in Figure 37. Thus, the volume enclosed by the insert reduces which, in turn, increases the pressure of gas inside the insert 5. Upon subsequent opening of the can 1 the closure means 6 operates in preference to the reversion of the lid 111. Another example is shown in Figures 38 and 39. In this example the insert 5 is formed with side walls 115 that concertina and with spring loaded ratchet arms 116. The insert also include a closure means 6. Again, the insert is filled with nitrogen at atmospheric pressure or slightly above whilst it has the configuration shown in Figure 38. After it is inserted into a can 1 and the can filled and sealed as the pressure inside the can builds up especially during a subsequent pasteurisation step the insert collapses to reduce its volume so that the pressure inside and outside the insert remains substantially the same. As the insert collapses its top wall 117 forces apart the sprung ratchet arms 116 until the top wall 117 passes their detents whereupon the insert is held by the sprung ratchet arms 116 and retained into its concertinaed configuration. A further example of volume reduction is shown in Figures 40 and 41. This example again shows a two-part insert with a main portion 120 and a lid 121 including a closure means 6. The main portion 120 is made from stretch blown PET and has a predetermined volume. The two-parts of the insert 5 are assembled in a nitrogen atmosphere at substantially atmospheric pressure. The insert 5 is again placed inside a can 1, the can filled and sealed. During pasteurisation the can and the beverage it contains is heated to a temperature of around 60°C for a period of around 20 minutes. During this a pressure of up to 4 Bar builds up inside the can 1. Upon heating the main body portion 120 of the insert to this temperature it tends to shrink to return to the shape that it was before it was blown. This shrinking is encouraged by the differential pressure between that subsisting in the inside of the insert 5 and that subsisting inside the can 1 with the result that there is a considerable volume decrease of the insert 5 during the pasteurisation process. As the can 1 and its contents cool the insert 5 remains at its new smaller volume and contains a super atmospheric pressure substantially the same as that subsisting inside the can 1. Additionally, the insert may be charged with a pellet of dry ice or other solid or liquified gas such as liquid nitrogen as it is assembled. By charging the insert immediately before it is placed in a can and the can filled it is possible for the pressure inside the insert to only build up to super atmospheric pressures as the filling operation is completed and results in a generally similar pressure building up inside the can. In this way, the build up of pressure inside the insert 5 is generally matched with the build up in pressure inside the can 1 so that no significant pressure differential exists until the ring-pull 3 on the can 1 is subsequently opened.

Claims: A sealed container (1) including a beverage (7) and a separate hollow insert (5), the insert containing a non-oxidising gas characterised by the insert being arranged to reduce its internal volume after sealing the container (1) to contain the gas at a super-atmospheric pressure, the insert including means (6) responsive to opening of the container (1) to provide communication between the inside of the insert (5) and the beverage (7) so that on opening of the container (1) the insert (5) which is closed apart from the means (6) jets gas via the means (6) into the beverage (7). A container according to claim 1, in which the means (6) has the form of pressure responsive valve means (25,26, 27; 32,33,35,36; 33,37,38,39; 33,41; 46; 51,52,53; 55, 56, 57; 60,61,62; 68,69,70,71; 68,69,72,73; 82,83,84,85; 94,95, 96) which, when exposed to the pressure difference subsisting between the gas inside the insert (5) and the atmospheric pressure subsisting in the container (1) after opening, opens to jet gas into the beverage (7) in the body of the container. A container according to claim 2, in which the valve means comprises a seating (83) surrounding the inside of an orifice (82) and a valve closure member (84, 85) which seats against and forms a seal with the seating, the insert (5) being formed of resilient material and including two opposed faces (81, 86) with the orifice (82) and seating (83) formed on one face (81) and the valve closure member (84, 85) attached to the inside of the other face (86) and extending to the seating (83) on the inside of the one face (81). A container according to any one of the preceding claims, in which the insert (5) contains gas at substantially atmospheric pressure on insertion into the container (1) and in which the pressure inside the insert (5) builds up after the insert is placed in the container and the container is filled with beverage. A container according to claim 4, in which the gas inside the insert (5) is substantially in equilibrium with that inside the container (1). A container according to any one of the preceding claims, in which the insert (5) is arranged to float on the surface of the beverage (7). A method of filling a container including the steps of: providing a container (1) and a separate closed hollow insert (5) containing a non-oxidising gas at substantially atmospheric pressure, filling the container (1) with beverage (7) and sealing it, and causing the volume of the hollow insert (5) to change to build up the pressure inside the insert to a super-atmospheric pressure, the insert (5) including means (6) responsive to the opening of the container (1) so that when the sealed container is opened the super-atmospheric pressure inside the insert jets gas from the insert into the beverage (7) in the container (1). A method according to claim 7, in which the insert collapses or concertinas and includes a mechanical lock (116) which is arranged to hold the insert (5) into its collapsed or concertinaed state. A method according to claim 7 or 8, in which means are provided which burst to allow gas to escape from inside the insert (5) on opening the container (1). A method according to claim 7, 8 or 9, in which the insert (5) changes its volume as a result of the increase in pressure which occurs inside the container (1) during pasteurisation.

Inventors: CAMERON-PRICE ERNEST JAMES, COSTELLO EDWARD ROGER, JAMIESON JAMES GERARD, KERSHAW PETER FRANK, MAULE DAVID, RADFORD MARK P, CAMERON-PRICE, ERNEST JAMES, COSTELLO, EDWARD ROGER, JAMIESON, JAMES GERARD, KERSHAW, PETER FRANK, MAULE, DAVID, RADFORD, MARK P.
Applicants: HEINEKEN TECH SERVICES, WHITBREAD & CO PLC, HEINEKEN TECHNICAL SERVICES B.V., WHITBREAD PLC
Application year: 1990
Main classification: B65D79
IPC codes: B65D85, B65D79, B65D25