EP0702649A1

EP0702649A1 - Container with head enhancing insert

Info

Publication number: EP0702649A1
Application number: EP94918435A
Authority: EP
Inventors: Mark Erich 3 Orchard Way SILLINCE; Timothy Wright; Erwin Anton Rosens
Original assignee: Whitbread PLC; Whitbread and Co Ltd; Heineken Technical Services BV
Current assignee: Whitbread PLC; Whitbread and Co Ltd; Heineken Technical Services BV
Priority date: 1993-06-18
Filing date: 1994-06-17
Publication date: 1996-03-27
Also published as: GB2279057B; CA2158838A1; AU674762B2; WO1995000416A1; GB2279057A; GB9412232D0; JPH08512011A; AU6975394A

Abstract

An openable but sealed container (50) containing a carbonated beverage (52) held under a super-atmospheric pressure includes a hollow insert (10, 12, 70, 80) which contains gas at a super-atmospheric pressure, which has a restricted orifice (22, 79, 84), which floats on the beverage (52), and which includes orientation means (18, 72, 86) which orientates the insert so that the restricted orifice (22, 79, 84) is submerged in the beverage (52). On opening the container (50), gas from inside the insert (10, 12, 70, 80) is jetted via the restricted orifice (22, 79, 84) into the beverage (52) to generate a close-knit creamy head as it is dispensed. The orientation means (18, 72, 86) is symmetrically arranged relative to a vertical plane containing the restricted orifice (22, 79, 84). Using a floating insert and arranging the orientation means in this way ensures that the restricted orifice (22, 79, 84)is always at the lowermost point of the insert. Thus the risk of the orifice being inadvertently exposed within the headspace in the container is minimised especially during dispensing of the beverage.

Description

CONTAINER WITH HEAD ENHANCING INSERT

TECHNICAL FIELD

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 their 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.

BACKGROUND ART

GB-A-1,266,351 discloses a number of beverage containers where a secondary chamber is provided which contains gas charged to a pressure substantially above atmospheric pressure. In one example, the secondary chamber is permanently in communication with the container via a restricted orifice and is charged with gas under pressure at the time of filling of the container. In another example, the secondary chamber is filled with gas and the restricted orifice sealed with gelatine or other non-toxic substance which is intended to retain the gas under pressure within the secondary chamber prior to and during filling but which dissolves after contact with the beverage for a period of time to open the restricted orifice. In a further example, the restricted orifice is provided in a flexible wall of the chamber which is exposed to the pressure in the main body of the container, the arrangement being such that pressure in the main body of the container holds the region of the wall around the restricted orifice sealed against a grommet until the container is opened, whereupon the resultant release of pressure results in the seal being broken and permits the gas under pressure from the secondary chamber to jet into the beverage through the restricted orifice. For a variety of reasons, none of these designs have met with commercial success.

GB-A-2,183,592 discloses a beverage container wherein, instead of gas being jetted from the secondary chamber by way of a restricted orifice, carbonated beverage or carbonated beverage followed by gas is jetted through a restricted orifice in order to induce fine bubble formation in the main body of the beverage. This system has been commercialised, but it is widely accepted that jetting gas only rather than carbonated beverage or carbonated beverage followed by gas, provides better bubble nucleation and hence better head formation. GB-A-2, 183,592 discloses a number of constructions wherein the secondary chamber may be constructed as an integral part of the beverage container or it may be formed as a discrete insert which is deposited or pushed into a conventional form of can, bottle or carton. Preference is expressed in GB-A-2,183,592 for an insert which is retained in position, for example at the bottom of the container, by an appropriate adhesive or by mechanical means. However, there is described the possibility of using a discrete insert which may be suspended or float in the beverage in the container provided that the restricted orifice is maintained below the surface of the beverage in the container on opening the container. The possibility of loading or weighting the insert to orientate the position of the restricted orifice is described.

EP-A-0,520,646 describes another proposal in which a beverage container has an insert with a restricted orifice which is arranged to jet gas only into the beverage. This insert is charged with gas by inverting the container promptly after it has been filled with beverage and the headspace above the beverage in the container pressurised so that the restricted orifice is exposed to pressure within the headspace above the beverage in the inverted container. Failure to ensure that the container remains inverted during the pressurization stages, including pasteurisation, results in the insert being filled with a significant amount of beverage, thereby losing all the benefits to be achieved by ejection of gas only under pressure from the insert when the container is opened. In practice, this can occur when there is an unforeseen production line stoppage which results in containers being stopped before inversion. Additionally, during pasteurisation, containers frequently fall over and are pasteurised on their side, in which orientation it is possible for substantial amounts of the beverage to enter the insert, especially since a high pressure exists in the container as a result of heating of the sealed container to the pasteurisation temperature.

With both the systems described in GB-A-2,183,592 and EP-A-0,520,646 since the insert is open via its restricted orifice before it is placed into the beverage container it is full of air. It is essential however to remove all of the air from the insert and container combination before filling it with beverage. The presence of oxygen inside the container leads to the beverage being oxidised with the resulting impairment of flavour and risk of microbial growth leading to, for example, acetification of the beverage when it contains alcohol. This removal of air is difficult to achieve in practice. Typically the container and insert combination is subjected to a purging regime using an inert gas such as nitrogen, carbon dioxide or a mixture of these and repeated pressurisation and depressurisation stages. This requires the use of an especially modified filling machine and substantially increases the filling cycle time. This difficulty has been overcome in a system disclosed in WO-A-91/07326 in which an insert which jets gas only into the beverage in the main body of the container is pre-pressurized with gas and includes closure means. The closure means remains sealed before filling and during the container filling operation but when the beverage container is subsequently opened, de-pressurization of the beverage container results in the insert releasing a surge of gas from a restricted orifice into the beverage to "seed" the required nucleation of dissolved gas bubbles to produce the required rich creamy foam. This system has met with considerable commercial success. Since the insert is sealed at all material times before the container is finally opened by the consumer the container and insert combination can be filled as easily, simply and quickly as conventional container. A disadvantage of this type of system is that the insert may contain a residual pressure after the container has been emptied. There is a risk a consumer will cut open the empty container and thus be able to interfere with a pressurised insert.

WO-A-91/07326 discloses a very large number of ways in which the pressurized gas insert can be formed and mounted within the beverage container. In most examples, the insert is mounted so that, in use, it is located at a fixed position. However, an example is also described where the insert floats in the liquid in the container and has a weight attached to its base for orientating the insert so that the restricted orifice is submerged in the beverage.

Although some of the prior art noted above does disclose the general idea of a floating insert none of the commercially adopted systems have used a floating insert. In general most of the systems which have been adopted rely on the insert being in a fixed position either to ensure that it works effectively on opening of the can or to ensure that it is charged with gas during pasteurisation. For example, if the insert described in EP-A-0,520,646 is displaced from its location adjacent the base of the can, when the can is inverted, the restricted orifice is not in the headspace during pressurisation and pasteurisation. Accordingly, the insert is filled with beverage and so does not operate as effectively as possible as a result of jetting liquid rather than gas.

Another problem which occurs with fixed inserts results from the way in which a container is handled during opening. When opening a bottle with a crown cork type closure the bottle is often tipped almost horizontally if opened using a fixed opener. Equally when opening an easy open feature, either a ring pull or a stay-on-tab on a can it is common to tilt the can on opening. In both cases, immediately after opening the closure the container is then tipped to dispense its contents. These actions can result in the restricted orifice of the insert not being immersed in the beverage whilst gas is being jetted from it. In this case the insert does not function correctly.

DISCLOSURE OF INVENTION According to this invention, an openable but sealed container containing a carbonated beverage held under a super-atmospheric pressure and including a hollow insert which contains gas at a super-atmospheric pressure, which has a restricted orifice, which floats on the beverage, and which includes orientation means which orientates the insert so that the restricted orifice is submerged in the beverage so that, on opening the container, gas from inside the insert is jetted via the restricted orifice into the beverage to generate a close-knit creamy head as it is dispensed, is characterised in that the orientation means is symmetrically arranged relative to a vertical plane containing the restricted orifice.

Using a floating insert and arranging the orientation means symmetrically relative to the restricted orifice ensures that the restricted orifice is always at the lowermost point of the insert and thus the risk of the orifice being inadvertently exposed within the headspace in the container is minimised especially during dispensing of the beverage after opening the container when it is particularly important for the orifice to remain submerged as the container is handled to open it and then tilted to dispense its contents.

The orientation means may have a positive buoyancy with respect to the beverage and be located towards or at the top of the insert but preferably it has a negative buoyancy and is located towards or at the bottom of the insert. When the material from which the insert is made has a negative buoyancy it is preferred that the orientation means is formed by providing a lower part of the insert with an additional feature or a greater wall thickness.

The insert is preferably symmetrical about two vertical planes of symmetry which are mutually perpendicular and which both contain the restricted orifice. It may be circularly symmetric about a vertical axis extending through the restricted orifice.

The insert is conveniently made in two parts which are arranged to be sealingly secured together. The two parts may be sealingly secured together by snap-fitting, screw- threading, welding, an adhesive or by folding and sealing inter-engaging flanges.

The gas in the insert is preferably an inert or non- oxidizing gas or gas mixture, preferably nitrogen and/or carbon dioxide. The insert may be moulded from a synthetic resin material such as polypropylene or be formed of metal such as lacquered aluminium, lacquered tin plate, polymer- coated aluminium, polymer-coated tin plate or tin-free steel. When the insert is made of metal and the container is also made of metal they are both preferably made of the same metal to facilitate re-cycling.

The insert may be pre-pressurised with gas by, for example, sealing its two parts together in a pressurised chamber and providing a valve or closure which prevents the gas from escaping from the insert until it has been sealed inside the container and the container subsequently opened. Ways in which this can be achieved are explained in detail in WO-A-91/07326. Another way in which this can be achieved is to provide a closure which is arranged to be permanently and irreversibly opened on being subjected to a temperature above a pre-determined threshold, or on being subjected to a pressure difference in which the pressure outside the insert exceeds that within. Such a closure seals the insert after its assembly and whilst the container is filled and sealed but is irreversibly opened subsequently, for example during a pasteurisation stage when the pressure is increased considerably.

The closure may be a member which is held against a sealing surface in the insert by the internal gas pressure, and it may be attached within the insert by any suitable means such as a weak heat seal, an interference fit, a heat sensitive adhesive, a temporary glue bond or a snap-fit engagement. In each case it is arranged to be detached when the external pressure exceeds the internal pressure or on application of heat. Alternatively, the closure may take the form of a weakened portion, membrane, tape or film which is located within the insert and which is supported so that it can withstand the internal gas pressure when the exterior pressure is less, but which is ruptured when the external pressure exceeds the internal pressure.

Preferably the insert is not pre-pressurised with gas and, instead, includes means in its upper part, which normally extend into the headspace to allow gas from the headspace to pressurise the insert. Preferably the insert includes a first and a second one-way valve, the first one-way valve being arranged to allow gas into the insert from the headspace and the second one-way valve forming the restricted orifice and allowing gas to leave the insert and be jetted into the beverage.

The effective volume of the inside of the insert is preferably about 2 to 7 ml, depending upon the size of the container and the type of beverage. The size of the restricted orifice when this is a hole of fixed diameter is typically 0.8 mm, but may vary from 0.05 to 3 mm depending upon the foam characteristics required and the type of beverage.

BRIEF DESCRIPTION OF DRAWINGS

Figures 1 and 2 are diagrammatic sections through a first example of insert before and after gas pressuri¬ sation, respectively;

Figures 3 and 4 are similar views of a second example;

Figures 5 and 6 are similar views of a third example;

Figures 7, 8, 9 and 10 are a sequence of sectional views of a beverage container containing the first example of insert showing, respectively, the conditions immediately after sealing of the container, at maximum pressure during pasteurisation, immediately prior to opening of the container, and immediately after opening of the container;

Figures 11 and 12 show the situation at maximum pressure during pasteurisation of the second and third examples of inserts, respectively;

Figure 13 is a sectioned perspective view of a fourth example of insert; Figure 14 is a sectioned perspective view of a fifth example of insert; and,

Figure 15 is a section showing the fourth example of insert in use.

DESCRIPTION OF PREFERRED EMBODIMENT

Referring now to Figures 1 and 2, the insert illustrated therein is symmetrical about its vertical axis and comprises moulded plastics (e.g. polypropylene) upper and lower components 10 and 12 which can be snap fitted together. The upper component 10 is bowl shaped and includes an outwardly directed annular sealing .lip 14 around its rim. The lip 14 snap engages with an inwardly directed lip 16 around the upper rim of lower component 12 which basically takes the form of a collar having a partition wall 17 adjacent its upper end so as to define a skirt 18 below the partition wall 17. The skirt 18 serves to orientate the insert in use. The partition wall 17 has a central depressed region 19 with a restricted orifice 20 through the centre thereof. The orifice 20 is thus arranged on the vertical axis of symmetry of the insert and discharges vertically downwardly when in its intended orientation. It will therefore be appreciated that the skirt 18 is symmetrically arranged relative to and around the orifice 20 and that it extends vertically downwardly below the orifice 20. Although not shown in the drawings, the skirt 18 is provided with a pair of diametrically opposed gas escape passages therethrough at its upper end, i.e. at a level above the restricted orifice 20.

A closure member in the form of a plastics disc 22 is temporarily secured by means of a weak heat seal 24 over the central depression 19 so that the disc 22 is substan¬ tially sealed against the partition wall 17. In order to pressurize the insert, the upper and lower components 10 and 12 with the disc 22 in the position illustrated in Figure 1 are introduced into a chamber (not shown) which is pressurized with gas at the required pressure, typically 55 psi gauge (380 KPa) and then snap-fitted together by means of the lips 14 and 16. Thus, there is defined a reservoir 23 containing the pressurized gas. The internal gas pressure in the reservoir 23 assists in maintaining the seal between the lips 14 and 16 and also in maintaining the seal between the disc 22 and the partition wall 17 after the upper and lower components 10 and 12 have been snap - fitted together as illustrated in Figure 2. In this condition, the insert can be removed from the pressurized chamber and is ready to be introduced into a beverage container.

Referring now to Figures 3 and 4, the insert is similar to that of Figures 1 and 2 and similar parts are accorded the same reference numerals. However, in this embodiment, upper and lower components 10 and 12 are each formed of a coated metal sheet and are secured together in sealing relationship by forming a seal by double folding as illustrated at 26 in Figure 4. In this second example, restricted orifice 20 is defined within a small plastics push-fit plug 28 engaged in an aperture formed in the base of the central depression 19 of partition wall 17. Such plug 28 serves to protect the cut edge of the coated metal against contact with the beverage in use, thereby to prevent metal pick-up by the beverage. An annular indent 30 is formed around the engaged components 10 and 12 adjacent the partition wall 17 in order to strengthen the side wall of the insert to prevent internal pressure from pulling apart the seam 26. In this embodiment, the disc 22 is formed from coated metal sheet which has edges curled downwardly and embedded into a ring of sealant material 32 which is designed to have only weak adhesion to the surface of the lower component 12 but permanent adhesion to the exposed cut metal edge of the disc 22. This sealant can be composed of a variety of food approved materials, such as can end sealant compounds and hot melt adhesives e.g. a reactive hot melt polyurethane adhesive. As in the first example, the insert of Figures 3 and 4 is assembled in the pressurized chamber in which double sealing at 26 and indenting at 30 take place.

In the third example illustrated in Figures 5 and 6, upper and lower components 10 and 12 are formed of coated metal sheet and are designed so as to be screw-threaded together over the region of the orientation skirt 18, with the pressure seal therebetween enhanced by application of a suitable adhesive or lining compound to the mutually- engaging screw threaded surface of the upper and lower components 10 and 12. The exposed cut edges 40 of the coated metal sheets from which the upper and lower components 10 and 12 are formed can be protected by an application of a lining compound 42 (see the left hand side of Figure 6) or by a curling-over operation to produce a curl edge 44 (see the right hand side of Figure 6) , or a combination of both if desired. In this example, the restricted orifice 20 is provided in a plug 28 which is snap-fitted into a central aperture of the base 12. The plug 28 is bowl shaped and forms the majority of the partition wall 17. The disc 22 is also integrally moulded with the plug 28 and is joined to it by an integral, thin strap or hinge 47 so that the disc 22 can be snap-fitted into sealing engagement with the rim of the plug 28.

Figure 7 shows the first example of insert in a beverage can 50 which has just been filled with beverage 52 so as to leave a headspace 54 and which has been sealed using seaming operation to fit a can top 56 having an easy opening tab 58. The insert may be introduced into the open can 50 before filling with the beverage 52 or it can be introduced after filling, or even during filling. The seaming of the can top 56 to the can 50 takes place in a known manner so that the can 50 is completely sealed with beverage 52 therein carbonated with carbon dioxide and a proportion of nitrogen. Additionally the headspace 54 may be charged with nitrogen in a known manner.

Filling, closing and pressurizing of the can 50 takes place so that the balance of dissolved gases used are adjusted so that the pressure within the can 50, when at equilibrium at normal domestic refrigeration temperature

(typically 5 to 10°C) , is below the initial gas pressure within the insert. The exact pressure levels vary depending upon the beverage being packed. In practice, it is desired to maintain the pressure difference in this respect within the range of about 35 to 180 KPa. With modern filling valve technology, this is readily achievable. In the case where the beverage is ale or stout having a carbonation level in the range of 1.0 to 1.1 vol/vol, it is preferred for the gas pressure within the insert to be about 380 KPa and for the final equilibrium pressure within the can to be in the range of about 200 to 345 KPa. In practice, it has been found for example that for 440 ml of beverage in a 500 ml can, the final equilibrium pressure for a 1.0 to 1.1 vol/vol carbonated beverage is the same as the pressure measured on exit from the seaming operation. This enables convenient control of can pressure levels using automatic can pressure measurement means which are readily available.

Once the can 50 has been sealed, it is subjected to pasteurisation in a known manner in order to ensure that the contents of the can are micro-biologically stable. This process requires the can contents to reach a temperature in the region of 60°C for about fifteen minutes. At maximum pasteurisation pressure, the can is inverted (see Figure 8) . During the heating stage of the pasteurisation process, dissolved gases in the can 50 come out of solution and result in a rapid rise in pressure within the can 50 where peak pressures reach levels of about 480 to 650 KPa depending upon the initial can pressure after closing. In contrast, the gas pressure inside the reservoir 23 of the insert does not rise significantly as the pressure only increases as a result of gas expansion alone. Thus, the pressure inside the can 50 exceeds the pressure inside the reservoir 23. Once the pressure in the main body of the can exceeds the internal pressure in the insert by a predetermined amount, typically about 35 KPa, the disc 22 is blown inwardly away from its sealing contact with the sealing surface of the partition wall 17. This process is irreversible so that, at all times thereafter, the inside of the insert communicates with the outside, i.e., with the interior of the can 50, via the restricted orifice 20. A portion 60 of the beverage enters the reservoir 23 throughout the pressure build-up stage of the pasteuris¬ ation process to equalise pressure between the insert and the can 50. Once the heating stage of the pasteurisation cycle is completed and the container is cooled, the pressure falls until, at about 30°C, the can 50 leaves the pasteuriser. At this stage, the pressure in the can 50 is in the region of 345 to 450 KPa. The pressure equalisation between the insert and the can takes place with the beverage being ejected from the insert back into the can 50 through the restricted orifice 20 during the pressure drop part of the cycle. The insert floats on the beverage in the can 50 with the restricted orifice 20 always lowermost as a result of the orientation skirt 18.

On exit from the pasteuriser, the can 50 is packed into secondary packaging and stored ready for distribution. After a period, typically less than two weeks, the can reaches full equilibrium conditions and the pressures within the can 50 and the reservoir 23 are in the region of 240 to 380 KPa depending upon ambient temperature. Through- out the storage period, as pressure is reduced inside the can due to gases becoming dissolved into the beverage, any beverage remaining inside the insert continues to be forced out of the insert until the pressure falls below the initial charging pressure of the insert. At this stage, further pressure drop results in ejection of gas from the insert into the main container, again to equalise pressure. At this stage, the condition of the can is typically as shown in Figure 9 where the disc 22 is no longer sealed against the partition wall 7 and there is no beverage within the insert.

When the can 50 is opened, preferably after refrigeration, by opening tab 60, the pressure in the can 50 is suddenly released, and this results in a jetting of tiny bubbles of pressurized gas from the reservoir 23 through the restricted orifice 20 into the beverage 52. This produces a creamy rich foam to the beverage when it is poured into a glass or other drinking receptacle.

The second and third examples of inserts operate in a similar way to that described above and the condition of cans fitted with such inserts at maximum pressure during the pasteurisation stage are illustrated in Figures 11 and

12.

Figure 13 shows a hollow insert 70 used in a fourth example. This insert 70 is generally cylindrical, having a circular base 72 made from aluminium having a thickness of 0.5 to 1 mm, side wall 74 and top 76 which are integrally formed from aluminium of 0.2 mm thickness. The aluminium is lacquered or coated. The side wall 74 of the insert is crimped around the base 72 with a can end sealant (not shown) sandwiched between. The inside volume of the insert 70 is 7 mm . The diameter of the insert 70 is similar to its height. The crimped edges of the insert are treated to prevent corrosion and this may be by the can end sealant. A first one-way duckbill valve 78 is included in the top 76 of the insert, and a second one-way duckbill valve is included in the base 72 of the insert. Both valves are inserted into holes which have a diameter smaller than that of the valve. This ensures that the walls of the hole bite into the valves 78, 79 so that the valves cover and protect the cut edges. This example of insert 70 is circularly symmetric about a vertical axis passing through the valves 78 and 79.

The insert is included in a container, such as a can 50, containing a beverage as shown in Figure 15. The insert floats on the surface of the beverage 52, and due to the extra thickness of the base and shape of the insert, floats with the base lying in a plane parallel to the surface of the beverage 52. In this way, the first duckbill valve 78 is in the headspace between the top of the beverage 52 and the top 56 of the container 50. The second duckbill valve 79 is submerged below the surface of the beverage 52. As the pressure inside the container 50 increases, immediately after filling and seaming, gas from the headspace enters the insert 70 via the first one¬ way valve 78. This gas cannot escape from the one-way valve 78, and does not escape via the second one-way valve 79 unless the pressure inside the insert 70 exceeds the pressure in the container 50.

Upon opening the container 50, the pressure inside the container 50 is vented to atmospheric pressure. At this time, the pressure inside the insert 70 is higher than that inside the container 50, and accordingly gas from the insert 70 is jetted into the beverage via the second one-way valve 79. The use of duckbill valves is particularly beneficial as the aperture through which the gas is jetted decreases as the gas pressure decreases, thereby ensuring the gas jetted into the beverage is jetted at a substantially constant, high velocity.

Figure 14 shows a fifth example of insert 80. This example is generally cylindrical having a circular end wall 81 when viewed axially and a curved side wall 82. Its length is greater than its diameter. Two one-way duckbill valves 83, 84 are mounted on opposite sides of the side wall 82. The insert is moulded from plastics material in two halves 85 and 86. Part 86 is generally made with thicker walls which ensures that the insert 80 floats in a plane parallel to the longitudinal axis passing through the centre of the end walls 81, with the first valve 83 above the surface of the beverage, and the second valve 84 below the surface of the beverage 52. As described above for the fourth example, gas from the headspace enters the insert 80 via the first valve 83, and is subsequently jetted into the beverage via the second valve 84 upon opening of the container 50.

The insert 80 is formed with a protrusion 87 which surrounds the second valve 84. This protrusion 87 protects the lips of the valve 84 from damage, especially when the container 50 is a bottle (not shown) . In this case the insert 80 is forced through the neck of the bottle. The protrusion 87 also contributes to the orientation means which orientate the insert 80 with its second valve 84 lowermost. Around the second valve 84, the side wall 82 of the insert 80 contains a portion 88 made with a thinner wall. This allows the protrusion 87 surrounding the valve, together with the valve 84, to be depressed towards the central longitudinal axis of the insert 80. In this way, the insert can be made smaller than the neck of a bottle allowing the insert 80 to be inserted into a bottle. However after the insert is pushed into the bottle, it returns to its normal state with the valve 84 and protrusion 87 protruding from the outer wall 82 of the insert. The insert 80 is then larger in cross sectional dimension than the neck of the bottle, and so it cannot be removed without breaking the bottle. This fifth example of insert 80 is symmetrical about two vertical, mutually perpendicular planes both of which include the valves 83 and 84.

Claims

C L A I M S

1. An openable but sealed container (50) containing a carbonated beverage (56) held under a super-atmospheric pressure and including a hollow insert (10, 12, 70, 80) which contains gas at a super-atmospheric pressure, which has a restricted orifice (22, 79, 84) , which floats on the beverage (52) , and which includes orientation means (18, 72, 86) which orientates the insert so that the restricted orifice (22, 79, 84) is submerged in the beverage (52) so that, on opening the container (50) , gas from inside the insert is jetted via the restricted orifice (22, 79, 84) into the beverage (52) to generate a close-knit creamy head as it is dispensed, characterised in that the orientation means (18, 72, 86) is symmetrically arranged relative to a vertical plane containing the restricted orifice (22, 79, 84) .

2. A container according to claim 1, in which the orientation means has a negative buoyancy and is formed by providing a lower part of the insert with an additional feature (18) or a greater wall thickness (72, 86) .

3. A container according to claim 1 or 2, in which the insert (80) is symmetrical about two mutually perpendicular vertical planes of symmetry which are mutually perpen¬ dicular and which both contain the restricted orifice (84) .

4. A container according to claim 1 or 2, in which the insert (10, 12, 70) is circularly symmetric about a vertical axis extending through the restricted orifice (22, 79) .

5. A container according to any one of the preceding claims, in which the insert is made in two parts (10, 12; 72, 74, 76; 85, 86) which are arranged to be sealingly secured together.

6. A container according to any one of the preceding claims, in which the gas in the insert is an inert or non- oxidizing gas or gas mixture, preferably nitrogen and/or carbon dioxide.

7. A container according to any one of the preceding claims, in which the insert is moulded from a synthetic resin material.

8. A container according to any one of claims 1 to 6, in which the insert is formed of the same metal as the container (50) .

9. A container according to any one of the preceding claims, in which the insert (70, 80) includes means (78, 83) in its upper part, which normally extend into the headspace to allow gas from the headspace to pressurise the insert (70, 80) .

10. A container according to claim 9, in which the insert (70, 80) includes a first (78, 83) and a second (79, 84) one-way valve, the first one-way valve (78, 83) being arranged to allow gas into the insert (70, 80) from the headspace and the second one-way valve (79, 84) forming the restricted orifice and allowing gas to leave the insert (70, 80) and be jetted into the beverage (52) .