Abstract:
A method and apparatus for the storage and/or maturation of an oxygen sensitive liquid beverage including: a vessel or tank adapted to hold a quantity of the liquid therein, said vessel having a low oxygen transfer rate from the atmosphere facilitating the reductive storage of said liquid; and a means of accommodating a gas permeable membrane, said gas permeable membrane having a high oxygen transfer rate relative to the vessel; wherein said membrane is in contact with said liquid thereby increasing the exposure of said liquid to oxygen in result.

Description:
FIELD OF THE INVENTION 
       [0001]    The present invention relates to the storage and/or maturation of an alcoholic beverage in particular to the maturation of wine. 
       BACKGROUND OF THE INVENTION 
       [0002]    Traditionally wooden barrels have been used to store and mature alcoholic beverages such as wine. Wood barrels are used because they allow the wine to breath during the maturation process and they impart favourable characteristics to the wine. The difficulty with wooden barrels is that they are expensive and only have a limited life. After roughly three years, most of a barrel&#39;s flavour compounds have been leached out and the pores in the wood have become clogged with detritus and are not able to function effectively. The wood barrels also allow for the evaporation and potentially the leakage of wine which means that they need to be topped up at intervals during the maturation process. Typically the barrel is topped up from another barrel. 
         [0003]    More recently stainless steel vessels have become popular. These vessels allow for bulk storage and maturation of wine. However they require the manual addition of oxygen (micro-oxygenation) and oak planks or chips. Furthermore, pitting of the stainless steel interior can destroy the integrity of the tank thereby rendering the tank useless. Pitting can occur when stainless steel is subjected to high concentration of chloride ions such as during cleaning of the vessel with a mild caustic solution. 
         [0004]    During the maturation process oxygen must be rationed to the wine. If too much oxygen comes into contact with the wine the oxidation of ethanol will produce vinegar. Accordingly it is important to minimise the atmospheric air coming into direct contact with the wine during maturation. This is particularly important in the headspace or ullage of the maturation vessel. If oxygen is not minimised in the headspace it can lead to aerobic bacterial spoilage of the wine. As can be appreciated the resultant formation of scum and mound is detrimental to the wine. 
         [0005]    In recent times thin walled polyethylene vessels have been used to mature wine. Polyethylene is easy to sanitise and can be cleaned with mild caustic preparation without the risks associated with stainless steel vessels. Furthermore, the material is gas permeable which allows for the rationing of oxygen. Unlike traditional wooden barrels however the material does not have pores that clog over time. The material therefore is therefore good at retaining its gas permeability. 
         [0006]    A problem with thin walled polyethylene vessels is that because they are flexible, they are difficult to transport. Furthermore, the vessels tend to expand and distort out of shape which can pose problems if they are being stored in close proximity to other vessels. The containers are also, because of thickness limitations to obtain the desired oxygen permeability, relatively fragile and need to be supported from collapsing under hydro static loads, 
         [0007]    Further still, wineries often require vessels which they can use not only for maturation purposes, but also for long term storage. Vessels constructed completely of gas permeable material are suitable only for maturation of liquid because of the thin walled polyethylene properties. They also fail to promote the controlled ingress of oxygen into the vessels during maturation, fermentation and oxygen exclusion. They are not suitable for holding liquid in a sealed inert environment, which means that additional gas impermeable vessels typically need to be purchased. 
         [0008]    A yet further problem encountered with prior art vessels of this type is that they typically include internal threads or fasteners for attaching a valve to the vessel. This often presents leaking, cleaning and sterilisation issues in that the internal fittings may promote, allow or permit the propagation of bacteria, such as acetobactors, which may spoil the wine. 
         [0009]    It is therefore an object of the present invention to overcome at least some of the aforementioned problems or provide the public with a useful alternative. 
       SUMMARY OF THE INVENTION 
       [0010]    Therefore in one form of the invention there is proposed an apparatus for the storage and/or maturation of a liquid, including: a vessel adapted to hold a quantity of the liquid therein, said vessel having a low oxygen transfer rate to facilitate long term storage of said liquid; and a means of accommodating a gas permeable membrane in a headspace of said vessel, said gas permeable membrane having a high oxygen transfer rate relative to the vessel to facilitate the controlled ingress of oxygen into said vessel. 
         [0011]    In a further form of the invention there is proposed an apparatus for storage and/or maturation of a liquid, including: a vessel adapted to hold a quantity of the liquid therein; a substantially rigid frame including a base plate adapted to support said vessel and prevent undesirable expansion of the vessel, said base plate being angled to facilitate draining of liquid out from the vessel. 
         [0012]    In a still further form of the invention there is proposed an apparatus for storage and/or maturation of a liquid, including: a vessel adapted to hold a quantity of the liquid therein; and a valve system including an integrally formed fitting extending a predetermined distance outwardly from a wall of said vessel, said fitting configured to receive a valve using an external fastening means, said valve used to control the passage of liquid there through. 
         [0013]    In a yet further form of the invention there is proposed an apparatus for storage and/or maturation of a liquid, including: a vessel adapted to hold a quantity of the liquid therein, said vessel having a low oxygen transfer rate to facilitate long term storage of said liquid; a means of accommodating a gas permeable membrane in a headspace of said vessel, said gas permeable membrane having a high oxygen transfer rate relative to the vessel to facilitate controlled ingress of oxygen into said vessel; a valve system including an integrally formed fitting extending a predetermined distance outwardly from said vessel, said fitting configured to receive a valve using an external fastening means, said valve adapted to control the passage of liquid there through; and a substantially rigid frame including a base plate adapted to support said vessel and prevent undesirable expansion of the vessel, said base plate being angled to facilitate stacking of said frames, and draining of liquid. 
         [0014]    Preferably the liquid is wine. 
         [0015]    In preference the wine is housed within the flexible vessel for the purposes of maturation. 
         [0016]    Alternatively the wine is housed within the flexible vessel for the purposes of storage. 
         [0017]    Most preferably the vessel is constructed from polyethylene. 
         [0018]    Preferably the base of the frame is adapted to accommodate the prongs of a forklift. 
         [0019]    In preference the bung tap includes a connection member adapted to be connected to a hose which is in communication with a source of compressed inert gas. 
         [0020]    Preferably, the fluid passage is located at the lowest point of the sump. 
         [0021]    In preference the apparatus includes an internal frame which is adapted to suspend at least one wooden member for the purpose of oaking of the liquid contained therein. 
         [0022]    In a still further form of the invention there is proposed an apparatus for the storage and/or maturation of a liquid, including: a vessel adapted to hold a quantity of the liquid therein, said vessel having a low oxygen transfer rate to facilitate long term storage of said liquid; and a means delivering gas into a permeable member located within the liquid, said permeable member having a high oxygen transfer rate relative to the vessel to facilitate the controlled ingress of oxygen into said vessel. 
         [0023]    In preference said means of delivering oxygen into the permeable member is an impermeable tube sealingly engaged to the vessel and having an upper opening exposed to the atmosphere and a lower opening in fluid connection with a permeable member, the permeable member located wholly within the liquid contained within the vessel and sealed against any liquid flow into the permeable member. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0024]    The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate several implementations of the invention and, together with the description, serve to explain the advantages and principles of the invention. In the drawings, 
           [0025]      FIG. 1  illustrates a perspective view of a tank system of the present invention in a stacked arrangement; 
           [0026]      FIG. 2  illustrates a perspective view of stacked tank frames forming part of the system of  FIG. 1 , in accordance with a first aspect of the present invention; 
           [0027]      FIG. 3  illustrates an enlarged perspective view of a tank lid forming part of the tank system of  FIG. 1 , in accordance with a second aspect of the invention; 
           [0028]      FIG. 4  illustrates an exploded, perspective view of the tank lid of  FIG. 3 , separated from the tank; 
           [0029]      FIG. 5  illustrates an enlarged perspective view of a tank base forming part of the tank system of  FIG. 1 , including an enlarged, exploded view of the tank valve in accordance with a third aspect of the invention; and 
           [0030]      FIG. 6  illustrates a second embodiment of the invention where oxygen transfer occurs to the liquid in the vessel within the liquid. 
       
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0031]    The following detailed description of the invention refers to the accompanying drawings. Although the description includes exemplary embodiments, other embodiments are possible, and changes may be made to the embodiments described without departing from the spirit and scope of the invention. Wherever possible, the same reference numbers will be used throughout the drawings and the following description to refer to the same and like parts. 
         [0032]    Referring to the drawings for a more detailed description, an apparatus or unit  10  is illustrated, demonstrating by way of example one arrangement in which the principles of the present invention may be employed. The apparatus  10 , as illustrated in  FIG. 1 , includes a flexible vessel or tank  12  and a substantially rigid frame  14 .  FIG. 1  illustrates apparatus  10  in a stacked arrangement with two individual units placed one on top of the other. As would be appreciated the ability to stack the units has significant space saving advantages. Each tank  12  includes a headspace defined by a lid  16 , and a valve assembly  20 . 
         [0033]    The frame  14  includes a substantially square base plate  22  supported in an elevated configuration by four upright legs  24  located at each corner. It is envisaged that the legs  24  will be constructed from steel square hollow sections (shs) or rectangular hollow sections (rhs) to provide the greatest strength whilst minimising the overall weight of the apparatus. The frame  12  further includes at least one brace member  25  joining two of the legs  24 . 
         [0034]    The base  22  is of a strength which allows a forklift to be used to transport the frame  14  by inserting forklift prongs beneath the plate  22 . In this way each unit  10  can be moved independently for the purposes of storage, cleaning or accessing the wine contained therein. Although not shown specifically in the drawings, the frame  14  also includes a forklift intrusion guard protecting the base of the tank from accidental intrusion by forklift prongs. 
         [0035]    Each leg  24  terminates at the bottom end in a locating lug  26 , which may for example be welded to the leg  24 . The upper end of each leg  24  is adapted to be received in a corresponding locating lug  26  of a frame  14  stacked there above, as illustrated in  FIGS. 1-2 . 
         [0036]    The tank  12  is preferably constructed from a food grade polyethylene polymer that is inert to wine. The material is inherently gas permeable, however, the tanks have a wall thickness, material density, and surface area to volume ratio&#39;s which are specifically formulated to allow for inert longer term storage. The tank wall could be coloured or translucent for clear view of contents and fill levels, and is of a heavy wall cylindrical design. This eliminates side wall bulging and the requirement for the frame to support the wall preventing it from bulging, and also assists cleaning. The tank is preferable rotationally moulded. 
         [0037]    In being configured this way, the tank  12  is also prevented from expanding undesirably. This also allows for unit  10  to be placed in close proximity to another without the risk of the tank  12  expanding in such a way as to encroach upon another unit  10 . As the reader would appreciate, if this was to occur between adjacent stacks it may result in a domino effect with disastrous consequences. 
         [0038]    It is envisaged that the tank  12  will be constructed out of polyethylene of a thickness which limits oxygen permeating through the tank walls. This ensures that the tank  12  can be used as a long term storage tank for many oxygen sensitive foodstuffs. 
         [0039]    Polyethylene is easy to sanitise and can be cleaned with mild caustic preparation without the risks associated with cleaning of stainless steel vessels with this type of solution. Furthermore the material does not have pores that clog over time as occurs in traditional wooden barrels. 
         [0040]    As is further illustrated in  FIGS. 1 and 2 , the base plate  22  of the frame  14  is slightly angled towards one side. For example, in the embodiment shown, the plate  22  is higher on the brace side than on the opposed side of the frame  14 . The tank  12  is adapted to be lowered onto the plate  22  between the legs  24  so that the valve assembly  20  is located at the lowest position of the angled plate  22  to facilitate flow out of the tank  12 . The valve assembly  20 , which shall be described in more detail below, can be used for both an inlet and an outlet for wine. The valve assembly  20  is also used during the cleaning process to remove the used mild caustic solution. 
         [0041]    As illustrated in  FIG. 3  the upper surface  28  of the tank  12  slopes upwardly and inwardly towards the headspace. This prevents air pockets from forming as the tank  14  is filled with wine. The apparatus  10  may further include an internal frame adapted to suspend portions of oak (not shown) within the wine. It is envisaged that the frame  14  will include at least one removable portion which is adapted to engage the oak portions. In this way the oak can be easily removed from the tank at any desired time during maturation of the wine. 
         [0042]    As mentioned, the headspace is defined by the round lid  16  of the tank  12 , shown in detail in  FIG. 4 . The lid  16  includes a body  32  having upper strengthening ribs  34  and a central aperture  36  defined by a male threaded shaft  38  which upstands from the body  32 . In a preferred embodiment, the male threaded shaft  38  is integrally moulded with the body  32 . The male threaded shaft  38  is adapted to be engaged by a female threaded nut  40 . Wedged between the threaded components to thereby seal aperture  35  is a liquid tight closure plate or membrane  44 . 
         [0043]    The closure membrane  44  can be made of a range of materials depending on the desired effect inside the tank  12 . For example, where oxygen transfer is required for the purpose of driven maturation, the closure membrane  44  could be in the form of a gas permeable silicon rubber membrane. Such membranes are significantly more permeable than polyethylene, and therefore require only a fraction of the surface area to permit equivalent oxygen transfers, hence the small membrane in the lid of the tank. Should the tank be required for reductive oxygen storage only, then the membrane  44  would be of a gas impermeable material. Alternatively, for storage purposes, the nut  40  could simply be replaced with a cap nut (not shown). 
         [0044]    It is further envisaged that the apparatus  10  will include multiple membrane types to suit specific jobs. For example, some wine may require greater oxygen transfer rates than others, and so a more gas permeable membrane  44  will be required, in comparison to a membrane used for wine that requires little oxygen rationing. It is to be further understood that the position of the membrane  44  need not be limited to the tank lid. 
         [0045]      FIG. 5  illustrates the valve assembly  20  in more detail. The valve assembly  20  is located in a low profile side wall recess  55  in the tank body at its base, and includes a fitting  56  which is integrally moulded with the tank wall. The fitting  56  is in the form of a circular cross section pipe  57  which extends forwardly from the tank  12  a short distance, and terminates in an annular shoulder  58 . A valve  60  includes an annular rearward portion  62  adapted to compress a gasket seal  64  against shoulder  58 , and a forwardly extending male threaded portion  66 . A hinged clamp  68  is used to couple the valve  60  and the fitting  56  by enclosing and gripping against both the fitting shoulder  58  and the rearward portion of the valve  60 . 
         [0046]    The male threaded portion  66  is then available for engagement with a female thread on the end of a hose fitting (not shown) for the purpose of transferring the vessel&#39;s liquid contents through the hose. 
         [0047]    This feature of the apparatus  10  is important because it does away with the need for internal fasteners, which are a common cause of bacteria propagation, leakage, and wine spoilage. In this case, the fitting  56  forms an integral part of the tank  12 , and the clamp  68  which is used to attach the valve  60  is an external fastener. The fitting is then able to communicate with known and standard hygienic fittings typically used by wineries, and the chance of bacteria propagation is greatly minimised. Although not shown, the tank  12  should also include a means of purging. 
         [0048]    The skilled addressee will now appreciate the many advantages of the present invention. The tank  12  provides unparalleled versatility in that it can be used as both a maturation vessel and a long term safe storage vessel, simply by changing between different membranes in the lid of the tank. For example, a wine maker would be able to successfully switch between barrel rates of oxygen driven maturation (up to 50 ml/l/yr), and inert longer term storage (&lt;5 ml/l/yr). The unit  10  creates opportunities for the controlled ingress of oxygen during maturation, fermentation and oxygen exclusion, whilst safely storing wine in a vessel capable of doubling cellar storage space by comparison with traditional oak barrel storage. Furthermore, the units  10  are particularly easy to clean, use a fraction of barrel cleaning resources, provide for complete control of oak integration and variation, do not require topping up, and are easily stacked and transported. 
         [0049]    It is envisaged that when say 4×4×4 units are stacked up, they will store up to 64,000 lts of wine. The same floor storage space and stack height using oak barrels stacked using typical barrel racks will store around 34,000 lts of wine only. 
         [0050]    Referring now to  FIG. 6  there is illustrated a further embodiment of the present invention that can introduce controlled amounts of oxygen into wine. Instead of the membrane  44  (or used in addition to it) an impermeable tube  70  extends into the wine and below the wine surface. The tube  70  includes an upper flange  72  that sits on top of the lid  16  thus supporting the tube  70 . Generally cylindrical the tube  70  has an upper opening  74  and a lower opening  76 , the lower opening extending well below the wine surface. Fitted to the end of the tube adjacent lower opening  76  is a permeable member or tube  78  sealed at its lower end  80  and having an upper opening  82 . The dimensions of both the impermeable tube  70  and the permeable tube  78  are chosen so that they sealingly engage each other at the lower opening  76  of the impermeable tube and the upper opening  82  of the permeable tube. Shown is the permeable tube extending around the impermeable tube, but of course it may also be the permeable tube being held within the impermeable tube in a mating arrangement. The extent of overlap between the two tubes will depend on their size and weight, that being dictated by the overall design and would be known to those versed in the art provided that it ensures that no wine can flow into the permeable tube  78 . To assist in securing the two together one could always consider having a hose barb or a clamp band, although these are not illustrated herein. 
         [0051]    Through its opening  74  the impermeable tube allows the passage of gases in and out of both the permeable and impermeable tubes. This opening may be covered by the previously illustrated flat permeable membrane  44  which then regulates the rate of oxygen ingress into the tube. Alternatively an impermeable flat seal may cover or a bung may be inserted into the upper aperture to prevent any oxygen ingress into the tube. 
         [0052]    The impermeable tube is fastened and sealed to the lid or out side of the vessel. 
         [0053]    It is an important feature of this embodiment that the ingress of atmospheric oxygen into the impermeable tube  70  is at a rate greater than that which oxygen may permeate through the lower permeable section of the tube  78  into the wine mass. Thus the oxygen content of the tube remains essentially equal with that of the prevailing atmospheric conditions. This feature allows the apparatus to introduce oxygen into the wine mass at controlled rates for the maturation of wine without the need for pressurising the tube or the requirement for oxygen to be driven through the tube by mechanical metering means as is the case with prior micro oxygenation apparatus. The current invention will introduce oxygen into a vessel containing wine at rates of between 5 ml/lt/yr and 200 ml/lt/yr. 
         [0054]    The impermeable tube is preferably made of stainless steel whilst the permeable tube is made from food grade material having known oxygen permeability properties. 
         [0055]    The reader should now appreciate the advantages of this embodiment. Having the permeable tube submerged under the wine surface prevents oxygen building up in the headspace of the wine vessel. High levels of oxygen in the headspace can encourage the cultivation of acetobactors on the wine surface which in high populations can result in wine spoilage. 
         [0056]    The amount of oxygen ingress may be varied by adjusting the wall thickness and/or surface area and/or length of permeable tube to compensate for varying capacity wine vessels and the wines potential to consume the oxygen through oxidative reactions. 
         [0057]    The apparatus may be adapted to be used in many types of wine storage vessels including polyethylene, stainless steel and oak barrels. In the case of oak barrels the impermeable section of the tube may fit into and pass through the upper sealing bung. 
         [0058]    Unlike of other forms of micro oxygenation the apparatus does not require oxygen to be pumped through the tube by means of an elaborate and precise mechanical metering apparatus. Such apparatus requires a power source to introduce optimal amounts of oxygen to wine for the purpose of controlled maturation. Any failure of this apparatus or the power source can have disastrous consequences. Further such apparatus requires a tube to transport oxygen or air from the metering apparatus to vessels storing wine. It should be appreciated that when smaller vessels are stacked in high density with each vessel having its own supply tube the potential for varying rates of metered oxygen ingress into individual vessels is limited. Further and where the vessels are in a stacked arrangement the supply tubes must be removed before the vessel can be moved, this procedure may be required to occur at considerable height and limits accessibility. 
         [0059]    Further advantages and improvements may very well be made to the present invention without deviating from its scope. Although the invention has been shown and described in what is conceived to be the most practical and preferred embodiment, it is recognized that departures may be made therefrom within the scope and spirit of the invention. 
         [0060]    Any discussion of the prior art throughout the specification should in no way be considered as an admission that such prior art is widely known or forms part of the common general knowledge in this field. 
         [0061]    In the summary of the invention, except where the context requires otherwise due to express language or necessary implication, the word “comprising” is used in the sense of “including”, i.e. the features specified may be associated with further features in various embodiments of the invention.