System and method

Abstract

A system for storing an alcoholic beverage comprising a rigid and airtight outer container, and a wooden barrel for containing an alcoholic beverage, and which wooden barrel is contained within the ou

Description

The present invention relates to a system and a method for storing an alcoholic beverage, and in particular which can reduce the losses of alcohol during aging. Whisky and similar spirits are required to be aged for many years, usually in defined barrels. For example, in the United States "straight whiskey" must be stored for at least two years in new, charred white oak barrels, whilst any whisky bearing the label "Scotch" has not only to be distilled in Scotland but also must be matured for a minimum of three years and one day in oak barrels. Oak barrels (and other wooden barrels, for example for other spirits) are porous to air, which diffuses into the barrel during aging, and to water and alcohol, which diffuse out of the barrel and evaporate to the surrounding atmosphere. This loss of alcohol / product is commonly referred to as the “Angels’ share”. The loss can be substantial, up to 50% of the product liquid volume can be lost in products which are aged for a number of years. It is necessary to use wooden barrels, and as noted often specific types of oak barrels, for the product to meet the required standards. In particular, the flavour of the matured spirit is generally reliant on complex interactions between the alcohol, compounds in the wood, and air or oxygen. Because of the necessity for oxygen to diffuse into the barrel it is generally not possible to simply paint or cover the outside of the barrel with an impervious coating. It has been proposed to place barrels inside of an outer container which is impervious to the alcohol. The theory is that alcohol and water can still diffuse out of the barrel and oxygen can still diffuse in, so the maturation process is unaffected, but the atmosphere inside the container will saturate with alcohol and an equilibrium reached preventing further losses. US 3001877, for example, describes placing a wooden barrel upright in an external container made of a material which is impervious to the vapor from the spirits. The suitable materials disclosed are mild steel, stainless steel and aluminium, with stainless steel and aluminium preferred. Whilst such containers are impervious to the alcohol vapours, such containers tend to be heavy and expensive. Also, due to the presence of potentially high concentrations of alcohol, which is flammable, and the risk of leaks or ruptures, it is necessary to minimise the risk of sparks and other ignition sources around the barrels. This can be difficult for metal barrels, which must be earthed, and must be carefully moved. It is accordingly an object of this invention to provide an improved system and method for storing, and in particular aging, of alcoholic beverages, which can prevent or reduce the “Angel’s Share” without the disadvantages of the prior art. Thus, in a first aspect the present invention provides a system for storing an alcoholic beverage, which system comprises (i) a rigid and airtight outer container, and (ii) a wooden barrel for containing an alcoholic beverage, and which wooden barrel is contained within the outer container, characterised in that said outer container is formed from polyethylene terephthalate (PET) or polyethylene naphthalate (PEN). In particular it is a particular feature of the present invention that the outer container is rigid, airtight and made from either PET or PEN. PET and PEN are polyester compounds. Both can be formed into large rigid containers, for example using processes such as blow moulding. (And as a specific example by injection stretch blow moulding.) Generally, PET is a polymer derived from terephthalic acid (or dialkyl terephthalate) and ethylene glycol units. Commercial production typically involves reaction of monoethylene glycol with dimethyl terephthalate or, more usually, terephthalic acid. Optionally a comonomer may be present. For example, 2,6-naphthalene dicarboxylic acid or isophthalic acid may be used in place of some of the terephthalic acid, whilst other diols may be used in place of some of the ethylene glycol. Preferably, however, the PET used in the present invention comprises at least 80wt%, such as at least 90wt%, of the total mass of the polymer of terephthalic acid (or dialkyl terephthalate) and ethylene glycol derived units. Preferred PET polymers for the present invention may exhibit a melting peak temperature between 225 °C and 255 °C, as identified during the second thermal scan in procedure 10.1 in ASTM D3418, when heating the sample at a rate of 10 °C / minute. Generally, PEN is a polymer derived from naphthalene-2,6-dicarboxylic acid (or an ester thereof) and ethylene glycol units. Optionally a comonomer may be present, for example, dimethyl phthalate or terephthalic acid, or an isomer of naphthalene-2,6-dicarboxylic acid may be used in place of some of the naphthalene-2,6-dicarboxylic acid, whilst other diols may be used in place of some of the ethylene glycol. Preferably, however, the PEN used in the present invention comprises at least 80wt%, such as at least 90wt%, of the total mass of the polymer of naphthalene-2,6-dicarboxylic acid (or an ester thereof) and ethylene glycol derived units. The containers formed have good strength but are much lighter than equivalently sized metal containers. They are also of a lower cost. Further, PET and PEN, as well as being impermeable to alcohol, air / oxygen and water, both have excellent chemical resistance, including in particular to mixtures of alcohol, air and water. PET and PEN are further both approved for food contact purposes. Thus, the system of the present invention can obtain the advantages sought by enclosing of a wooden barrel in a metal or other container to prevent loss of the product, but whilst avoiding some of the issues of the prior art and providing other advantages. Further, a yet further advantage is that the containers can be made transparent, either as a whole or by inclusion of “windows”. A particular advantage of this is that the enclosed wooden barrel can still be viewed. This can enable monitoring of potential issues such as corrosion or fungus growth. It also means that, if desired, analysis techniques based on visible light or other radiation to which the container is transparent, can be applied if it is desired to monitor the vapour composition inside the container without opening the container. Typically the wooden barrel is an oak barrel, these of course being the most common barrel type for storing of whisky and some other beverages. The barrel may be any barrel which is typically used for storing spirits. In many cases these are characterised by their size. The present invention is particularly preferred where the wooden barrel has an internal volume of 150 to 275 litres. This volume generally encompasses what are known as a “Standard” barrel or a “hogshead” barrel, for example. In particular, in general a smaller volume barrel has a larger surface area to volume ratio, which can cause faster aging. However, this is at the expense of requiring significantly more barrels. Barrels in the range 150 to 275 litres are considered provide an optimum, whilst being within the range for which PET and PEN containers which can contain the barrel can be readily formed. A particularly preferred system is used for storing and aging of spirits, and particularly brandy, rum or whisky. Thus, in preferred embodiments the wooden barrel is a barrel for containing a spirit, and more preferably for storing of brandy, rum or whisky. Most preferably the wooden barrel is a barrel for containing whisky. In preferred embodiments of the system, the barrel does contain the alcoholic beverage, preferably a spirit and most preferably whisky i.e. the system comprises a wooden barrel which contains the alcoholic beverage. Typically the outer container is sufficiently large that the barrel can be comfortably accommodated inside, and manipulated inside if needed. (Barrels containing alcoholic beverage are heavy. If the containers are too “close fitting” it is difficult to get barrels in and out.) Containers significantly larger the barrel are however also not preferred since the additional volume provides no particular benefit. Most preferably, the outer container has an internal volume of between 1.2 and 3 times the internal volume of the barrel. The container may be any suitable shape that can contain the wooden barrel. It may, for example, be a similar shape to the barrel, only larger in dimensions, or it may be a cylinder, or a cuboid. “Barrel-shape” or cylindrical outer containers are generally preferred. To assist in the insertion and removal of the wooden barrel the outer container is preferably formed of a. a main body with an opening large enough to insert or remove the wooden barrel, and b. a lid or other cover which covers the opening to make the container airtight. Typically both the main body and the lid / cover will be made of the same material, whether this is PET or PEN. An airtight seal may be obtained by close fitting of the parts, or by use of a gasket or similar if required. To ensure that the wooden barrel sits in the central portion of the container there may be provided one of more supports inside the outer container and on which the wooden barrel can sit within the container. An example of this is a shelf as shown in US 3001877, which is suitable for horizontally orientated barrels and containers. Alternatively any other form of barrel stand can be provided inside the container, however, to enable the container and barrel to sit on their respective sides, with the barrel still held in the centre of the container. As has already been noted, the container, if not transparent as a whole, may be provided with a transparent window, which is also preferably of PET or PEN material. This enables the enclosed wooden barrel to still be viewed. The outer container may, in some embodiments, be provided with one or more ports through which air or oxygen can be introduced into the container, and in particular into the volume between the container and the wooden barrel. We have also noted that the use of a transparent container allows, if desired, certain analysis techniques based on visible light or other radiation to which the container is transparent, to be applied if it is desired to monitor the vapour composition inside the container without opening the container. Alternatively, or in addition, one or more ports may also be provided by which a probe can be inserted into the container to perform an analysis, or by which vapour can be withdrawn for ex-situ analysis. In some embodiments, the outer container may be rated for an internal pressure above atmospheric pressure. Such a pressure may be up to 5 atmospheres for example. This enables an increased pressure of air / oxygen to be provided in the container which can accelerate the aging. In some embodiments the system may further be provided with means to heat the barrel to above ambient temperature. This can also provide the possibility of accelerated aging. It can also reduce the amount of liquid condensed inside container (outside of the barrel). During the aging of alcohol beverages it is often desirable to sample the beverage. Wooden barrels for aging of alcoholic beverages may include a sample hole and a bung which blocks this. In a preferred embodiment of the present invention the wooden barrel is provided with a bung which can be removed for sampling, and the outer container includes a port or opening adjacent to the bung to enable sampling of the alcohol beverage without removal of the barrel from the container. The system of the first aspect of the present invention is used for storing, and preferably aging alcoholic beverages. Thus, in a second embodiment, the present invention provides a method for storing, and preferably aging, an alcoholic beverage, which method comprising storing the alcohol beverage in a system which comprises (i) a rigid and airtight outer container, and (ii) a wooden barrel for containing an alcoholic beverage, and which wooden barrel is contained within the outer container, characterised in that said outer container is formed from polyethylene terephthalate (PET) or polyethylene naphthalate (PEN). 5 The preferred features of the system as used in this second aspect are as defined for the system of the first aspect. Typically in this second aspect the alcoholic beverage may be stored for at least 2 years, such as 3 or more years.

Claims

1. A system for storing an alcoholic beverage, which system comprises(i) a rigid and airtight outer container, and(ii) a wooden barrel for containing an alcoholic beverage wherein the wooden barrel has an internal volume of 150 to 275 litres, and which wooden barrel is contained within the outer container, characterised in that said outer container is formed from polyethylene terephthalate (PET) or polyethylene naphthalate (PEN).

2. A system according to claim 1 wherein the wooden barrel is an oak barrel.

3. A system according to claim 1 or claim 2 wherein the wooden barrel is a“Standard” barrel or a “hogshead” barrel.

4. A system according to any one of the preceding claims wherein the outer containerhas an internal volume of between 1.2 and 3 times the internal volume of the barrel.

5. A system according to any one of the preceding claims wherein the wooden barrelis a barrel for containing whisky.

6. A system according to any one of the preceding claims wherein the outer container is formed ofa. a main body with an opening large enough to insert or remove the wooden barrel, andb. a lid which covers the opening to provide an airtight container.

7. A system according to any one of the preceding claims wherein there are provided one of more supports inside the outer container and on which the wooden barrel can sit within the container.

8. A system according to any one of the preceding claims wherein the outer container is provided with one or more ports through which air or oxygen can be introduced into the container, and in particular into the volume between the container and the wooden barrel.

9. A system according to any one of the preceding claims wherein the outer container is rated for an internal pressure above atmospheric pressure.

10. A system according to any one of the preceding claims wherein there is provided means to heat the barrel to above ambient temperature.

11. A system according to any one of the preceding claims wherein the wooden barrel is provided with a bung which can be removed for sampling, and the outer containerincludes a port or opening adjacent to the bung to enable sampling without removal of the barrel from the container.

12. A system according to any one of the preceding claims wherein the outer container is transparent as a whole or includes transparent windows also made of PET or PEN5 material.

13. A method for storing, and preferably aging, an alcoholic beverage, which method comprising storing the alcohol beverage in a system according to any one of the preceding claims.10