METHOD FOR CLEANING A WOODEN BARREL

Description

TECHNICAL FIELD OF THE INVENTION

[0001] The invention relates to a method of cleaning a wooden barrel, such as a cask or a barrique, used for wine aging allowing the barrel to be reused for, for example, further wine aging, alcoholic beverage aging or alcoholic beverage transportation. TECHNICAL BACKGROUND OF THE INVENTION

[0002] Aging in a barrel is intended, using physicochemical reactions, to obtain, for example, wine, spirits, beer or vinegar. As is well known, the wood of the staves has pores, through which the liquid penetrates to a certain depth into the staves during aging. Conversely, air passes into the liquid through these same pores, providing it with micro-oxygenation.

[0003] Liquid seeping between or into the staves can increase the risk of microbiological contamination, particularly due to the sulfur-based elements used during aging, which can be responsible for defects in the resulting product. This is why, after an aging process, particularly for red wine, barrels are generally resold to be replaced with new ones. Because of its infiltration, a barrel is resold for ten to twenty times less than a new one. However, the oak wood of the barrels is generally not structurally altered.

[0004] It is known to plane or sand the inner face of the staves and bottoms of a barrel in order to mechanically remove a thickness at least equivalent to the infiltration thickness of the wine. However, this reduction in thickness increases the risk of leakage and breaks the wood fibers to the point of degrading the mechanical strength of the barrel. Indeed, the mechanical strength of the staves is important, their arrangement in a circle allowing in particular to distribute the force exerted on each of the other staves. The barrel can thus be stored, rolled, tilted, empty or full, without risk of breakage.

[0005] Furthermore, other solutions without material removal, typically by circulating water in the barrel, exist, but do not allow, like planing or sandblasting, the removal of all the residues infiltrated in depth, in particular those based on sulfur. Documents US 2017 / 283287 A1, US 2004 / 245281 A1, US 2014 / 065013 A1 and CN 109 568 620 A are known. SUMMARY OF THE INVENTION

[0006] The invention aims in particular to provide a new method for cleaning a wooden barrel making it possible in particular to remove any residue infiltrated into the wood fibers such as microbiological contamination induced during a process of maturing an alcoholic beverage or such as red wine pigments by restoring to the barrel an appearance and intrinsic properties similar or identical to a new condition without damaging the wood fibers.

[0007] To this end, the invention relates to a method for cleaning a wooden barrel. characterizedin that it comprises a step of disinfecting the interior of the barrel comprising at least one phase of introducing hydrogen peroxide inside the barrel and a phase of introducing water vapor into the barrel before or after the phase of introducing hydrogen peroxide inside the barrel in order to sanitize the wood of the barrel in depth and to remove any residue infiltrated into the fibers of the wood such as pigments.

[0008] Advantageously according to the invention, the oxidizing power of hydrogen peroxide makes it possible to reduce microbiological contamination to a negligible or even undetectable quantity, and in particular any sulfur-based element, without making the wood of the barrel more sensitive to oxidation. In addition, any coloring of the wood, caused during the aging of an alcoholic beverage in the barrel, is removed, allowing a neutral appearance of the wood to be restored throughout the barrel. Finally, the internal surface of the barrel is, advantageously according to the invention, entirely disinfected by eliminating in particular any volatile or surface acidity. The barrel is therefore made completely neutral with respect to the aging of the alcoholic beverage for which it may have been used, which allows it to be reused, in particular for a new aging of the alcoholic beverage under the same conditions as a new barrel.

[0009] The steam introduction phase heats and softens the wood fibers to open the pores of the wood sufficiently to allow the hydrogen peroxide to penetrate the wood to a sufficient depth to remove any residue embedded in it. In addition, the steam introduction phase brings the hydrogen peroxide to a temperature where its sanitizing effectiveness is optimal.

[0010] The invention may also include one or more of the following optional features, taken alone or in combination.

[0011] During the phase of introducing hydrogen peroxide into the barrel, a 35 mol% hydrogen peroxide solution is inserted into the barrel in a proportion of 0.5 ml to 3.5 ml per liter of barrel interior volume and, preferably, in a proportion of 1.0 ml to 2.3 ml per liter of barrel interior volume.

[0012] The phase of introducing water vapor into the barrel is used, preferably, to bring the hydrogen peroxide inside the barrel to a temperature between 60°C and 80°C.

[0013] The disinfection step includes a phase of closing the barrel after the phase of introducing water vapor into the barrel to, by cooling, create an internal depression and gradually close the pores of the wood in order to improve the evacuation of any residue infiltrated into the wood fibers. It is understood that this closing phase allows in particular to gradually reduce the temperature of the interior volume of the closed barrel so that the depression promotes a flow of air through the pores of the wood from the external face to the internal face and the contraction of the pores of the wood will mechanically expel any residue present in the pores towards the interior volume of the barrel 1 without the extracted residues being able to become embedded there again. The duration of the closing phase can thus be between one hour and four hours.

[0014] The barrel closure phase is maintained for at least a predetermined duration preferably dependent on the temperature to which the barrel was heated during the water vapor introduction phase. If the temperature difference compared to the ambient temperature is very significant, it may be necessary to provide a pressure compensation device such as a valve to prevent the depression inside the barrel created by the cooling from causing deterioration of the barrel bottoms.

[0015] During the disinfection step, the drum can be moved on itself to improve the homogenization of the disinfection of the interior of the drum. Typically, the movement on itself can be considered after the phase of introducing hydrogen peroxide inside the drum and / or during the phase of closing the drum.

[0016] Preferably, the disinfection step includes a final phase of washing the inside of the barrel in order to rinse the wood inside the barrel. This phase can also be used to descale the inside of the barrel.

[0017] Additionally, depending on the soiling of the barrel, a pre-washing step of the inside of the barrel before the disinfection step may be preferable in order to remove any excess organic matter deposited on the internal surface of the barrel. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Other features and advantages of the invention will emerge clearly from the description given below, for information purposes only and in no way limiting, with reference to the appended drawings, in which: there figure 1 is a schematic view of a barrel for maturing an alcoholic beverage; figure 2 is a partial view of a stave after aging red wine; the figure 3is a functional diagram of the method according to the invention. DETAILED DESCRIPTION OF AT LEAST ONE EMBODIMENT OF THE INVENTION

[0019] In the various figures, identical or similar elements bear the same references, possibly with the addition of an index. The description of their structure and function is therefore not systematically repeated.

[0020] In all that follows, the orientations are the orientations of the figures. In particular, the terms "upper", "lower", "left", "right", "above", "below", "forward" and "backward" are generally understood in relation to the direction in which the figures are represented.

[0021] By "cask 1" we mean all types of wooden containers, such as barrels or casks, intended for the aging, ageing or transport of alcoholic beverages such as wine, cider, brandy, beer or vinegar.

[0022] An example of a barrel 1 made of wood, such as oak, is shown in figure 1 . The barrel 1 comprises, in a known manner, a substantially cylindrical part formed by staves oriented vertically and pressed against each other by circles 4. The substantially cylindrical volume is closed at the top and bottom by bases 2 (only one visible at the figure 1 ). Finally, one of the staves 3, called the master stave, has a bung hole which is hermetically sealed with a silicone bung 5.

[0023] The aging in a wooden barrel 1, such as for example a 225 I barrel, is intended, using physicochemical reactions, to obtain for example wine. In a known manner, the wood of the staves 3 has pores, through which, on the internal face 7, the liquid to be aged penetrates to a certain thickness E into the staves 3 during aging. Conversely, through the external face 6, the air passes into the liquid to be aged through these same pores, providing it with micro-oxygenation.

[0024] Liquid seeping between staves 3, or into staves 3, can increase the risk of microbiological contamination, which can cause defects in the aged product. This is why, after an aging process, particularly for red wine, barrels 1 are generally resold to be replaced by new ones. Because of its infiltration, a barrel 1 is resold ten to twenty times cheaper than a new one. However, the wood, for example oak, of barrels 1 is generally not structurally altered.

[0025] The invention aims in particular to provide a new method 11 for cleaning a wooden barrel 1 making it possible to restore a neutral internal surface 7, in particular with regard to its coloring and its tannins, in order to be able to use it again as a new barrel 1. Advantageously according to the invention, the method 11 makes it possible in particular to remove any residue infiltrated into the wood fibers, including any red wine pigments, by restoring the barrel 1 to an appearance and intrinsic properties similar or identical to a new state without damaging the wood fibers.

[0026] For this purpose, the method 11 for cleaning a wooden barrel 1 comprises a step 13 for disinfecting the interior of the barrel 1. Depending on the state of dirtiness of the internal surface 7 of the barrel 1, the cleaning method 11 may comprise a step 21 for pre-washing the interior of the barrel 1 before the disinfection step 13 in order to remove any excess organic matter deposited on the internal surface 7 of the barrel 1. The pre-washing step 21 may be obtained, for example, by circulating steam and / or hot water in the barrel 1, i.e. introducing it into the barrel 1 via an inlet pipe passing through the bung hole with the free possibility of escaping from the barrel 1 via an outlet (which may be the bung hole facing downwards), for a period of around five minutes. Of course, depending on the degree of dirtiness of the internal surface 7 of the barrel, the duration of the pre-wash step 21 may be longer or shorter than five minutes.

[0027] Advantageously according to the invention, the disinfection step 13 comprises at least one phase 15 of introducing hydrogen peroxide (H 2 O 2 ) inside the barrel 1 in order to sanitize the wood of the barrel 1 in depth. Indeed, the applicant has discovered that the oxidizing power of hydrogen peroxide makes it possible to reduce to a negligible or even undetectable quantity any sulfur-based element without making the wood of the barrel 1 more sensitive to oxidation. In addition, any coloring of the wood, caused during the aging of an alcoholic beverage in the barrel 1, is removed, making it possible to restore a neutral appearance of the wood over the entire barrel 1. Finally, the internal surface 7 of the barrel 1 is, advantageously according to the invention, entirely disinfected by eliminating in particular any volatile or surface acidity.Barrel 1 is therefore made completely neutral in relation to the aging of the alcoholic beverage for which it may have been used, which allows it to be reused, in particular for a new aging of the alcoholic beverage in conditions similar to a new barrel 1.

[0028] During the phase of introducing hydrogen peroxide into the barrel 1, a 35 mol% hydrogen peroxide solution is inserted into the barrel 1 through the bung hole in a proportion of 0.5 ml to 3.5 ml per liter of internal volume of the barrel 1 and, preferably, in a proportion of 1.0 ml to 2.3 ml per liter of internal volume of the barrel 1, i.e. in particular 1.0 ml, 1.1 ml, 1.2 ml, 1.3 ml, 1.4 ml, 1.5 ml, 1.6 ml, 1.7 ml, 1.8 ml, 1.9 ml, 2.0 ml, 2.1 ml, 2.2 ml and 2.3 ml per liter of internal volume of the barrel 1.

[0029] Obviously, depending on the concentration of the hydrogen peroxide solution, i.e., whether it is greater or less than 35 mol%, the amount of hydrogen peroxide will have to be maintained. In this case, the 35 mol% hydrogen peroxide solution is chosen because it is readily available commercially. Typically, for a 225 I drum 1, it has been observed that a volume of between 250 ml and 500 ml, i.e. in particular 250 ml, 260 ml, 270 ml, 280 ml, 290 ml, 300 ml, 310 ml, 320 ml, 330 ml, 340 ml, 350 ml, 360 ml, 370 ml, 380 ml, 390 ml, 400 ml, 410 ml, 420 ml, 430 ml, 440 ml, 450 ml, 460 ml, 470 ml, 480 ml, 490 ml and 500 ml, of a 35 mol% hydrogen peroxide solution is satisfactory.

[0030] The disinfection step 13 further comprises, preferably, a phase 16 of introducing water vapor into the barrel 1 after the phase 15 of introducing hydrogen peroxide inside the barrel 1. The purpose of using water vapor is to improve the penetration and effectiveness of the disinfection in the wood of the barrel 1. Concretely, the phase 16 of introducing water vapor heats and softens the fibers of the wood to sufficiently open the pores of the wood in order to make the hydrogen peroxide penetrate into the wood to a sufficient thickness to remove any residue embedded therein, typically to a thickness at least equal to that E illustrated in figure 2 containing residues from breeding. In addition, phase 16 of introducing water vapor allows the hydrogen peroxide to be brought to a temperature where its sanitizing effectiveness is optimal.

[0031] Phase 16 can be obtained by mounting a bung in the bung hole of the drum 1 which comprises a steam inlet pipe towards the interior of the drum 1 connected to a boiler making it possible to pressurize and heat the interior of the drum 1. The boiler is preferably configured to create a wet water vapor, that is to say that the water in the form of gas is mixed with water in the liquid form. Consequently, the introduction phase 16 can inject a water vapor comprising a proportion of between 0% and 40% of water in the liquid form by total weight of the wet water vapor injected, the remainder being vaporized water, that is to say in the form of gas.

[0032] The duration of phase 16 is between two and eight minutes depending on the desired heating temperature and the power of the boiler. It has been observed that hydrogen peroxide is most effective between sixty degrees Celsius and eighty degrees Celsius, that is to say in particular 60°C, 61°C, 62°C, 63°C, 64°C, 65°C, 66°C, 67°C, 68°C, 69°C, 70°C, 71°C, 72°C, 73°C, 74°C, 75°C, 76°C, 77°C, 78°C, 79°C and 80°C. In fact, preferably, phase 16 is used to bring the hydrogen peroxide to at least sixty degrees Celsius while preferably avoiding exceeding eighty degrees Celsius. For example, a time of six minutes with a steam generation of 40 kg·h-1< was satisfactory.Furthermore, it has been observed that reversing phases 15 and 16, i.e. carrying out phase 16 of introducing steam and then phase 15 of introducing hydrogen peroxide inside the barrel, does not allow for as good an effect to be obtained as implementing phase 15 followed by phase 16, particularly in terms of the effectiveness of removing residues in the wood such as red wine pigments.

[0033] According to one variant, a compressor is mounted between the boiler and the inlet pipe in order to carry out phase 16 under a higher pressure, such as twenty bars. Of course, the maximum pressure will be adapted according to the drum 1 to be cleaned in order not to exert an internal pressure likely to damage drum 1. The aim of this variant is to combine heat and pressure to make disinfection step 13 more effective. Empirically, it has been found that this variant makes it possible to reduce the time required for phase 16 for the same effectiveness as without the use of overpressure.

[0034] Preferably, the disinfection step 13 also includes a phase 18 of closing the barrel 1 after the phase 16 of introducing water vapor into the barrel 1 in order to allow the hydrogen peroxide to act on the components of the wood of the barrel 1 until the temperature of the barrel 1 drops, preferably naturally, to ambient temperature, that is to say preferably without cooling other than exchanges with the ambient air.

[0035] Concretely, the closing phase 18 can be obtained by closing the inlet pipes or by replacing the plug comprising these pipes with a plug 5 illustrated in figure 1. It is understood that this closing phase 18 makes it possible in particular to gradually reduce the temperature of the interior volume of the closed barrel 1 to create an internal depression and gradually close the pores of the wood capable of improving the evacuation of any residue infiltrated into the wood fibers without the extracted residues being able to become embedded there again. Thus, the depression will promote a flow of air through the pores of the wood from the external face 6 to the internal face 7 and the contraction of the pores of the wood will mechanically expel any residue present in the pores towards the interior volume of the barrel 1.

[0036] In addition, the closing phase 18 of the drum is maintained for at least a predetermined duration preferably dependent on the temperature to which the drum 1 was heated during the phase 16 of introducing the water vapor. Typically, the higher the temperature, the shorter the closing phase 18 could be because the hydrogen peroxide will act more quickly but the longer it will be necessary to wait if it is desired that the temperature of the drum 1 naturally drops back to room temperature. Thus, the hotter the hydrogen peroxide is (typically between sixty degrees Celsius and eighty degrees Celsius) and is kept hot during the closing phase 18, the stronger its oxidizing action. The duration of the closing phase 18 can be between one hour and four hours depending on the drum 1 used, that is to say in particular 1 hour, 1.5 hours, 2 hours, 2.5 hours, 3 hours, 3.5 hours and 4 hours.It was found that a phase 18 closure time of two hours for a 225 litre drum 1 was satisfactory.

[0037] If the temperature difference compared to the ambient temperature is very significant, it may be necessary to provide a pressure compensation device such as a valve, for example in the bung, to prevent the depression inside the drum 1, created by the cooling, from causing deterioration of the bottoms 2 of the drum 1.

[0038] During the disinfection step, the barrel 1 can be moved on itself to improve the homogenization of the sanitization of the interior of the barrel 1. Typically, the movement on itself can be envisaged after the phase of introducing hydrogen peroxide inside the barrel and / or during the phase of closing the barrel. Such a movement can consist of stirring the barrel 1 manually or using a mechanism for rotating the barrel 1 whose rotation axis is movable to induce an automatic complex stirring movement.

[0039] Preferably, disinfection step 13 finally includes a final phase 19 of washing the barrel 1 in order to rinse the wood inside the barrel 1. This phase can also be used to descale the inside of the barrel 1.Thus, the washing phase 19 may, without limitation, comprise a first cycle of circulation of hot water in the barrel 1, i.e. introduction into the barrel 1 via an inlet pipe passing through the bung hole with the free possibility of escaping from the barrel 1 via an outlet (which may be the bung hole facing downwards), such as for example between forty degrees Celsius and eighty degrees Celsius for a duration of between one minute and ten minutes, followed by a second cycle of circulation of ozonated cold water, i.e. comprising ozone (O 3 ), in the barrel 1, such as for example at the temperature of the water distribution network, typically between fifteen degrees Celsius and twenty degrees Celsius for a duration of between one minute and ten minutes. An optional cycle of circulation of water vapour may be provided for a duration of between one minute and ten minutes between the first and second cycles.

[0040] The applicant had measurements carried out on barrels 1 which had been used, in particular, for aging red wine and which had benefited from the implementation of the cleaning method 11 according to the invention. The tests made it possible to verify that the oxidizing power of hydrogen peroxide makes it possible to reduce to a negligible or even undetectable quantity any sulfur-based element used during aging, such as, for example, sulfur or sulfur oxides.

[0041] It was also possible to check that the internal surface 7 of barrel 1 no longer contains hydrogen peroxide and that it is more sensitive to oxidation than new wood. In addition, any coloration of the wood, caused during aging, is removed, allowing a neutral appearance of the wood to be restored throughout barrel 1, in particular without degradation of the wood fibers.

[0042] Finally, the internal surface 7 of the barrel 1 is, advantageously according to the invention, entirely disinfected by eliminating in particular any volatile or surface acidity such as ethyl acetate. The barrel 1 is therefore made completely neutral with respect to the aging of the alcoholic beverage for which it may have been used, which allows it to be reused in particular for a new aging of the alcoholic beverage under conditions similar to a new barrel 1. It has also been possible to measure that the ellagitannin content is lower than a new barrel, which makes it possible to make the barrel 1 cleaned by the method 11 according to the invention more neutral than a new barrel 1.

[0043] The invention is not limited to the embodiments and variants presented and other embodiments and variants will be clear to those skilled in the art. Thus, the embodiments and variants can be combined with each other without departing from the scope of the invention. Without being limiting, it may be envisaged to carry out a heating treatment of the internal surface 7 of the barrel 1 making it possible to personalize the aromatic profiles of the barrel 1 after implementing the method 11 according to the invention without significant difficulty compared to a new barrel 1.

Claims

1. Method (11) for cleaning a wooden barrel (1) characterised in that it comprises a step (13) of disinfecting the inside (7) of the barrel (1) including at least one phase (15) of introducing hydrogen peroxide inside the barrel (1) and a phase (16) of introducing steam in the barrel (1) after the phase (15) of introducing hydrogen peroxide inside the barrel (1) in order to sterilise the wood of the barrel (1) in depth and remove any residue infiltrated in the wood fibres such as pigments.

2. Method (11) for cleaning a wooden barrel (1) characterised in that it comprises a step (13) of disinfecting the inside (7) of the barrel (1) including at least one phase (15) of introducing hydrogen peroxide inside the barrel (1) and a phase (16) of introducing steam in the barrel (1) before the phase (15) of introducing hydrogen peroxide inside the barrel (1) in order to sterilise the wood of the barrel (1) in depth and remove any residue infiltrated in the wood fibres such as pigments.

3. Method (11) according to claim 1, wherein, during the phase (15) of introducing hydrogen peroxide inside the barrel (1), a 35 % mol solution of hydrogen peroxide is inserted in the barrel (1) in a proportion of 0.5 mL to 3.5 mL per litre of inner volume of barrel (1) and, preferably, in a proportion of 1.0 mL to 2.3 mL per litre of inner volume of barrel (1).

4. Method (11) according to one of claims 1 or 3, wherein the phase (16) of introducing steam in the barrel (1) is used to raise the temperature of the hydrogen peroxide inside the barrel (1) to between 60 °C and 80 °C.

5. Method (11) according to one of claims 1 or 3 to 4, wherein the step (13) of disinfecting comprises a phase (18) of closing the barrel (1) after the phase (16) of introducing steam in the barrel (1) in order, on cooling, to create an internal depression and progressively close the wood pores to improve the evacuation of any residue infiltrated in the wood fibres.

6. Method (11) according to the preceding claim, wherein the duration of the phase (18) of closing is between 1 hour and 4 hours.

7. Method (11) according to claim 5 or 6, wherein, during the step (13) of disinfecting, the barrel (1) is displaced about itself so that the sterilisation of the inside of the barrel (1) is more homogeneous.

8. Method (11) according to one of claims 1 or 3 to 7, wherein the step (13) of disinfecting comprises a final phase (19) of washing the inside of the barrel (1).

9. Method (11) according to one of claims 1 or 3 to 8, comprising a step (21) of prewashing the inside of the barrel (1) before the step (13) of disinfecting.