Beverage Package

This invention relates to a package for maintaining a beverage at a sub- ambient temperature. The package is particularly suitable for maintaining a liguid beverage at a temperature below that of a domestic refrigerator compartment. The invention also relates to a method of maintaining a beverage at a sub-ambient temperature.

It is customary for certain liguid beverages, particularly fermented beverages such as lager and cider, to be consumed at a sub-ambient temperature. In the domestic environment, this involves placing the beverage package in a compartment of a domestic refrigerator for several hours before it is intended to consume the beverage. Domestic refrigerators tend to maintain a temperature of about 6 ⁰ C, which has previously been considered sufficient to provide an acceptable drinking experience.

In recent years, there has been a trend for licensed bars and restaurants to serve fermented beverages at temperatures significantly lower than that of a domestic refrigerator. Such beverages are often marketed as being "superchilled", and are typically served at a temperature of about 3 ⁰ C or less. In order to serve beverages at this temperature, commercial establishments install dedicated refrigeration eguipment. However, such eguipment is not generally appropriate for small scale domestic use.

According to the invention, there is provided a package for maintaining a beverage at a sub-ambient temperature, the package comprising a primary chamber containing the beverage and a secondary chamber containing a cooling material, the cooling material having a freezing temperature higher than a freezing temperature of the beverage, wherein the primary and secondary chambers are in thermal communication with each other so that, in use, heat may flow from liguid beverage to frozen cooling material.

The invention thus provides a package for a liquid beverage intended to be consumed at a temperature below that of a domestic refrigerator compartment, such as a beer, cider, wine, spirit mixer or non-alcoholic beverage. The package may be stored at a retail outlet location at a temperature between the freezing temperatures of the beverage and the cooling material. In this state, the beverage is in the liquid phase and the cooling material is in the solid phase. When the beverage is purchased by a consumer, heat inevitably flows into the beverage from an ambient or domestic refrigerator environment, but heat also flows out of the beverage into the frozen cooling material. The latter flow of heat enables the beverage to be maintained at a low temperature.

The invention takes advantage of the fact that when the cooling material undergoes a phase change from solid to liquid, i.e. it melts, energy may be supplied to the cooling material without a corresponding increase in its temperature. Thus, a temperature differential between the frozen cooling material and the liquid beverage can be reduced without causing an increase in the temperature of the cooling material. Of course, the cooling material will eventually melt, after which the beverage and the cooling material will reach thermal equilibrium, the cooling effect having been "spent".

The package may be a disposable beverage package and/or may be for up to 5 litres, preferably up to 3 litres, and most preferably up to 1 litre, of beverage.

The secondary chamber containing the cooling material is preferably smaller than the primary chamber containing the beverage. In a particularly preferred embodiment, the secondary chamber is enclosed by the primary chamber, with the secondary chamber being free to move within the primary chamber. Such an arrangement provides for efficient thermal communication between the chambers.

Alternatively, the primary chamber may be enclosed, at least in part, by the secondary chamber. The secondary chamber may, for example, form a sleeve

for the primary container. The sleeve may be detachable from the primary chamber.

The primary chamber may be a can, a bottle or a carton and the secondary chamber may be a hollow plastic moulding or a sealed pouch formed from a sheet material. Sealed pouches, such as sealed four-edged pouches, can be efficiently formed from a sheet material. Sealed pouches can also be made using a form, fill and seal (FFS) process, and can be formed with thin walls to provide efficient thermal communication between the chambers.

The secondary chamber may alternatively be manufactured by blow-moulding, extrusion, dipping, sheet fabrication, drawing, stamping, pressing or glass blowing.

The primary chamber may contain from 100ml to 5000ml, preferably from 200ml to 500ml, and most preferably 440ml, of beverage and the secondary chamber may contain from 20ml to 2000ml, preferably from 20ml to 100ml, and most preferably 60ml, of cooling material (as measured in the liquid phase). Such volumes are expected to provide a desirable balance of sufficient cooling effect and packaging efficiency. The volume of cooling material in the secondary chamber may be in the range of 10% to 20% of the volume of beverage in the primary chamber.

Suitable materials for the primary and secondary chambers include glass, aluminium alloy, cardboard, steel and polymers, including laminates formed from any combination of these and other materials. One embodiment comprises a plastic primary chamber containing a metallic secondary chamber.

Another embodiment comprises a metallic primary chamber containing a metallic or plastic secondary chamber. Another embodiment comprises a metallic primary chamber having a plastic secondary chamber in the form of a sleeve.

Either or both of the chambers may be coated, and/or surrounded by an insulating material, such as a foam or cardboard. Insulating material may be effective in extending the duration of the cooling effect provided by the cooling material.

The freezing temperature of the beverage is preferably -1 ⁰ C or less. For example, the beverage may comprise a water based fermented beverage, containing alcohol. However, the beverage may alternatively comprise other types of beverage, such as water based soft drinks containing sugars, fruit extracts and/or vegetable extracts. The beverage may be carbonated or non- carbonated.

The freezing temperature of the cooling material may be 8 ⁰ C or less, preferably 5 ⁰ C or less, and most preferably in the range -1 ⁰ C to 5 ⁰ C. For example, the cooling material may comprise water. The cooling material could be pure water. Alternative cooling materials include oils, waxes and other substances, including mixtures thereof.

A difference in the freezing temperatures of the beverage and the cooling material may be in the range 1 ⁰ C to 1O ⁰ C, more preferably 1 ⁰ C to 5 ⁰ C.

The secondary chamber may also contain at least one solid particle for stirring the cooling material and maintaining its homogeneity. The solid particles are preferably formed from metals, polymers and/or ceramics, including glass. The secondary chamber may also contain other additives in solid, liquid or gaseous form. The additives may be dissolved or suspended in the cooling material.

The primary and secondary chambers are preferably not in fluid communication, and at least the primary chamber is preferably hermetically sealed. The primary chamber may be provided with a non-resealable opening, such as those used for disposable packages.

The package may comprise a plurality of the secondary chambers described above.

According to another aspect of the invention, there is provided a method of maintaining a beverage at a sub-ambient temperature, the method comprising: packaging liquid beverage with a chamber containing liquid cooling material, the cooling material having a freezing temperature higher than a freezing temperature of the beverage, the beverage being in thermal communication with the cooling material; lowering the temperature of the beverage package until the liquid cooling material freezes, the beverage remaining in the liquid phase; and exposing the beverage package to an ambient temperature environment, so that heat flows from the environment to the liquid beverage and from the liquid beverage to the frozen cooling material.

The temperature of the liquid beverage rises until in equilibrium with the environment, but this rise in temperature is slowed by the flow of heat to the cooling material.

The chamber containing liquid cooling material may be produced using a form, fill and seal (FFS) process. The chamber may, for example, be in the form of a pouch or blister pack.

A preferred example of the invention will now be described, purely by way of example, with reference to the accompanying drawings, in which: Figure 1 is a schematic perspective view of a package according to the invention; and

Figure 2 is a graph of a heating curve for water used to explain how the package shown in Figure 1 works.

The invention provides a package comprising two chambers in thermal communication with each other. A primary chamber contains a beverage, and a secondary chamber contains a cooling material having a freezing temperature higher than a freezing temperature of the beverage. In use, the

temperature of the package may first be lowered to a temperature between the freezing temperatures of the beverage and the cooling material. The package is then exposed to a higher temperature environment, and heat flows from the environment to the liquid beverage and from the liquid beverage to the frozen cooling material.

Figure 1 is a schematic perspective view of the package 1. The package 1 comprises a primary chamber in the form of a conventional aluminium alloy beverage can 3. The can 3 is cylindrical in shape and has an internal volume of approximately 500ml. The can 3 has a domed base 5 and a flat lid 7. The lid 7 has a ring-pull 9 attached to a weakened region by which the can 3 may be opened in a conventional manner.

The can 3 contains 440ml of a fermented beverage 11 containing alcohol. The fermented beverage 11 has a freezing temperature of -3 ^or Vy .

The package 1 also comprises a secondary chamber contained within the can 3. The secondary chamber is in the form of a sealed plastic pouch 13 made from sheet material using a form, fill and seal (FFS) process.

Form, fill and seal processes will be well known to those skilled in the art. They essentially comprise the steps of: forming an enclosure, for example, from sheet material or by moulding; filling the enclosure with desired contents; and then sealing the enclosure closed.

The plastic of the pouch 13 is a food grade plastic material, such as polypropylene. The plastic pouch 13 has an internal volume of 60ml which is substantially filled with a cooling material in the form of pure water 15. The water, of course, has a freezing temperature of O ⁰ C. The plastic pouch 13 may additionally contain a small amount of air, CO2 or N ₂ (not shown), so as to minimise stress in the wall of the pouch 13 when the water 15 freezes and expands.

The plastic pouch 13 has a small wall thickness of approximately 50 microns, so that the fermented beverage 11 in the can 3 and the water 15 in the pouch 13 are maintained in highly efficient thermal communication with each other. However, the fermented beverage 11 and the water 15 are not in fluid communication with each other.

The package 1 may be filled and sealed on an industrial scale using conventional processing equipment. In particular, the can 3, without the lid 7, is passed in an upstanding condition to a filling station. At the filling station, the fermented beverage 11 and the water filled pouch 13 are transferred into the can 3. The can 3 is then passed to a sealing station, at which the headspace in the can 3 is purged of air and the lid 7 is sealed in place.

In use, the package 1 is maintained at a retail outlet location at a temperature of -2 ⁰ C. At this temperature, the fermented beverage 11 is in the liquid state and the water 15 in the pouch 13 is in the solid state, i.e. it exists as ice.

The temperature of -2 ⁰ C is maintained by storing the package 1 in a commercial refrigerator having thermostatic temperature control means. It should be noted that conventional domestic refrigeration equipment is not generally capable of maintaining a temperature of -2 ⁰ C. Although the temperature of the stored package 1 may be allowed to fluctuate slightly, it is important that it is maintained between -3 ⁰ C and O ⁰ C, so as to prevent freezing of the fermented beverage 11 or melting of the water 15, respectively.

When the package 1 is purchased by a consumer, it is removed from the commercial refrigerator in which it was being stored. After purchase, the package 1 is usually placed by the consumer in an ambient environment having a temperature of about 2O ⁰ C. The package 1 may alternatively be placed by the consumer in a domestic refrigerator compartment having a temperature of about 6 ⁰ C.

In either case, the outside environment of the package 1 has a higher temperature than the package itself, and so heat flows from the environment to the package, and more particularly into the fermented 11 beverage. As a result, the temperature of the fermented beverage 11 slowly rises. Similarly, heat then flows from the fermented beverage 11 into the frozen water 15 in the pouch 13, thereby slowly raising the temperature of the frozen water.

Eventually, the temperature of the frozen water 15 will reach O ⁰ C. However, at this stage, even though the temperature of the fermented beverage 11 continues to rise, the temperature of the frozen water 15 stops rising. This is because the heat passing into the frozen water 15 is used to melt the water, rather than to raise its temperature. This will be briefly explained with reference to Figure 2, which shows a heating curve for water.

Figure 2 is a graph showing the temperature of water as heat is gradually added. Referring to the Figure, it can be seen that, below a temperature of O ⁰ C, the temperature of frozen water rises steadily with the addition of heat. Similarly, between O ⁰ C and 100 ⁰ C, the temperature of liquid water rises steadily with the addition of heat (albeit at a different rate). However, at a temperature of O ⁰ C, the temperature of frozen water does not rise, even though heat is being added. This is because the heat is being used to melt the frozen water, rather than to raise its temperature. This heat used to melt a solid is known as the heat of fusion.

The heat of fusion for water is 334J/g. Thus, for the frozen water 15 in the capsule, the heat of fusion is approximately 20KJ. Because the frozen water 15 remains at a temperature of O ⁰ C during the transition from solid to liquid, and absorbs 20KJ of heat from the fermented beverage 11 during the transition, the frozen water 15 has a significant cooling effect on the beverage 1 1 .

In this way, the temperature of the beverage is maintained at a lower temperature than would have been the case had the package not have

contained the plastic pouch 13 containing the water 15. More specifically, the beverage is maintained at a temperature below that of a conventional domestic refrigerator for longer, facilitating the consumption of the drink at a characteristic "superchilled" temperature.

Eventually, the frozen water 15 will melt, after which the fermented beverage 11 and the water will reach thermal equilibrium. The cooling effect of the water 15 is then spent.

A specific example of the invention has been described above. It will be apparent to those skilled in the art that various modifications and changes may be made without departing from the scope of the invention.

For example, the above example is a package containing a fermented beverage such as lager or cider. However, the invention is also applicable to other beverages such as soft drinks containing sugar. For a given beverage, a cooling material should generally be selected that has a freezing temperature a few degrees centigrade higher than that of the beverage.

The freezing point of a cooling material may be modified by adding impurities, as will be appreciated by those skilled in the art.

The above example comprises a secondary chamber freely located within a primary chamber. However, other arrangements are possible, provided that the chambers are in thermal communication.

Although the heat flow in the above example is described as being from the environment to the beverage and then from the beverage to the cooling material, other flows are possible. For example, where the secondary chamber is provided as a sleeve around the primary chamber, heat may flow from the environment directly to the cooling material.

The above example is described in the context of a commercial application, i.e. the sale of beverages at a retail outlet. However, the invention is equally applicable to the domestic environment, and refrigeration equipment may be adapted therefor.