WO2005025825A1

WO2005025825A1 - Method for the extraction of cork-containing material

Info

Publication number: WO2005025825A1
Application number: PCT/EP2004/010133
Authority: WO
Inventors: Kurt Stork
Original assignee: Degussa Ag
Priority date: 2003-09-10
Filing date: 2004-09-10
Publication date: 2005-03-24
Also published as: DE10341637A1; AU2004272265A1

Abstract

The invention relates to a method for extracting cork-containing material with the aid of a compressed gas at temperatures ranging between 10 and 120 °C and pressures ranging between 10 and 600 bar. Extraction takes place in isobaric conditions while the compressed gas flows through the charge in a radial or axial direction and the charge that is to be extracted is combined with an adsorbing material. The inventive method allows cork plates, cork granules, bottle cork, or agglomerated cork, for example, to be quantitative removed from organic compounds such as pentachlorophenol, trichloroanisole, and tetrachloroanisole as well as waxes and fats such that the purified cork-containing materials can be used without reservation in the food sector and particularly in the beverage sector.

Description

Process for the extraction of cork-containing material

description

The present invention relates to a method for the extraction of cork-containing material with the aid of a compressed gas and under defined temperature and drain conditions.

Cork is a natural, impermeable, lightweight material made from the bark ("bark") of certain oaks, such as the cork oak, which is typically found in the countries bordering the Mediterranean, in Europe and in North Africa.

Cork is a widely used material and is used in particular in the food sector as a closure for bottles but also in so-called crown corks as insert sheets, preferably in the beverage sector.

It is in the nature of things, especially when using bottle corks, that the cork parts facing the bottle contents come into contact with the drinks contained in the containers (mostly wine, sparkling wine, sparkling wine and champagne).

Although the natural product cork is a highly elastic, dimensionally stable, compressible and liquid-impermeable material with high gas permeability, it also contains numerous ingredients due to its original function as bark, which in their natural function as repellents, e.g. serve as feeding protection.

When the untreated natural product cork comes into contact with food-grade liquids, e.g. drinks, it is inevitable that in Depending on the storage time and thus the contact time, soluble cork constituents pass into the liquid media. This manifests itself at least in a taste-changing manner, which is commonly referred to as the "cork" of the beverage. These substances that are corked into the drinks develop a mostly unpleasant, musty taste and, together with the cork dyes that also dissolve in the drink, make the affected drinks inedible.

This typical cork of the wine or its musty smell and taste is not only due to the ingredients naturally present in the cork, they are also produced by mushroom cultures that grow on the peeled cork bark, which is usually stored in plate form.

Typical compounds that these fungal strains release to the cork are methyl isoborneol and its derivatives, which give off a musty and camphor-like odor, geosmin with a typically earthy odor and methylthio-ethyl-pyrazine with a musty and sulfur-like odor. Alcohols and unsaturated ketones produce mushroom-like scents. In this connection, chloranisols such as 2,4,6-TCA (trichloroanisole) and 2,3,4,6-TeCA (tetrachloroanisole) are particularly worth mentioning.

Numerous methods are known from the prior art in order to separate the cork from the secondary ingredients or metabolic products mentioned.

In the historical process by F. Bordas from 1904, cork parts are first heated in a heat chamber at 120 ° C for 10 minutes and then exposed to a vacuum, whereupon an increased pressure is again applied. Then the mixture is finally heated to 130 ° C. for a further 10 minutes.

In the so-called "Champcork process", cork parts are exposed to a steam at 130 ° C under pressure conditions of 180 kPa for 18 to 20 minutes, after which the pressure is released to atmospheric pressure. Both of these methods, however, have the disadvantages that they are not very efficient in removing the organic compounds responsible for the undesirable taste and, moreover, they cannot kill microorganisms efficiently.

Ana M. Miianda et al ("High Pressure Extraction of Cork with CO ₂ and 1.4-dioxane", Process. Techno 1. Proc. (1996), 12 "High Pressure Chemical Engineering", p. 417 bis 422). Accordingly, cork is treated with CO ₂ and dioxane under high pressure conditions of 170 bar at temperatures of 160 to 180 ° C, whereby suberin, a component of the cell walls of cork in the form of modified lignin, is removed. However, this method is not suitable for treating cork, which is then to be used as bottle cork.

US Pat. No. 5,364,475 describes a process for the purification of wood and in particular for the extraction of pentachlorophenol (PCP) -like compounds, wherein the wood is first cut into small pieces and then subjected to a treatment with a supercritical liquid, such as CO ₂ . Methanol, ethanol and acetone can be used as co-solvents. Since this process is only suitable for the removal of PCP (including trichloroanisole and tetrachloroanisole) and, moreover, it is only able to extract these undesirable ingredients from cork to a limited extent, it is unsuitable for further treatment with regard to food-grade applications.

German published patent application DE 42 23 022 also teaches a process for extracting tar oils from old wood or wood waste, the starting material first being brought to a particle size between 10 and 40 mm and then with a supercritical extraction liquid such as CO ₂ or an aliphatic C ₃ . ₅ -Carbohydrate is being treated. If the duration of treatment is sufficient, the tar oil content should reach a certain level Threshold can be reduced. A co-solvent, such as ethanol or isopropanol, can also be used in this process in proportions of 2 to 5% by volume, based on the moisture content of the wood.

European patent application 140061 describes a method for extracting ingredients from natural products using a pressurized fluid, the ingredients then being bound to an adsorbent material. This method, which is said to be primarily suitable for decaffeinating tea leaves with the aid of CO ₂ , makes particular use of radial flow guidance through the bed of tea leaves, the compressed CO _{2 being} fed from the outside through the bed into an axial Horil cylinder. This process with radial guidance of the extraction medium can only be carried out with homogeneous starting materials which, above all, should be very light, tend to stick or have an unstable structure which cannot withstand major pressure differences. For extraction materials such as cork, which due to its natural elasticity can also withstand higher pressure differences and neither tends to stick or has no unstable structures, this method with radial fluid guidance is therefore not very suitable.

From the international patent application WO 01/23155, a process for the treatment and extraction of cork-typical organic compounds with the aid of compressed liquids is known: The treatment of cork or cork-based materials should consequently succeed in that the cork material under pressure conditions of 10 to 600 bar and is brought into contact with a compressed liquid at temperatures between 10 and 120 ° C. The extraction liquid should preferably be in the supercritical state, carbon dioxide, nitrogen oxide and C 5 _-5 hydrocarbons being particularly suitable.

This method is intended to overcome the disadvantages of the prior art, which consist in the fact that none of the previously known methods for Treatment of cork uses compressed liquids - under pressure conditions and therefore does not take into account the specific properties of cork, such as elasticity and density. In particular with regard to the composition of cork, in relation to suberin, lignin and cellulose, no suitable method is known from the prior art to remove secondary cork ingredients or decomposition products caused by fungi to a sufficient extent.

The method described last according to WO 01/23155 is also not suitable for economically removing trichloroanisole, tetrachloroanisole, pentachloxphenol as well as waxes and fats from cork-based material to such an extent that the material thus extracted is subsequently safe in the food sector and especially in Beverage sector can be used.

For the present invention, the object is therefore to provide a process for the extraction of cork-containing material with the aid of a compressed gas at temperatures between 10 and 120 ° C. and pressures between 10 and 600 bar, which, with a relatively simple procedure, produces organic contaminants from cork-containing Material removed to such an extent that it can subsequently be used in the food sector without negative effects.

This object was achieved with a method in which the extraction is carried out under isobaric conditions, in which the compressed gas flows radially or axially through the bed and in which the bed to be extracted is combined with an adsorption material.

Surprisingly, this method has shown that, in contrast to the known methods for treating cork, not only the undesired organic compounds such as PCP, TCA and TeCA as well as waxes and fats can be removed below their detection limit, but also shaped cork products , such as bottle corks, can be extracted without losing their substance-specific properties, such as elasticity and density, Liquid impermeability and gas permeability, and in particular the dimensional stability, lose.

The advantages of this process were not to be expected to this extent.

Although the method according to the invention is not restricted to any specific cork-containing material, it has proven to be very advantageous if cork boards, cork granules, cork powder, bottle cork and / or pressed cork are used as cork-containing materials. The starting material used may also have been subjected to a mechanical and / or chemical and / or physical pretreatment, such as that e.g. Comminution steps, acid-base treatment measures or a cooking process and how they are also taken into account by the present invention.

Temperatures which are between 40 and 100 ° C., more preferably between 60 and 80 ° C., are preferably used in the process according to the invention. The process pressures used are preferably between 80 and 400 bar, more preferably between 100 and 150 bar, and particularly preferably between 120 and 140 bar.

The weight ratio between the compressed gas used and the cork-containing material is not limiting for the present method, but a corresponding weight ratio that has been found to be suitable is 1 to 100: 1. Preferred weight ratios of 20 to 70: 1 and in particular 40: 1 are to be used in the context of the present invention for special applications.

It is also preferred according to the invention if the compressed gas is in the supercritical state.

It is stated, among other things, that the compressed gas flows radially or axially through the bed. Especially with regard to the radial driving style it has proven to be advantageous if the flow direction leads from the inside to the outside. The compressed gas is first fed into a centrally arranged axial inner cylinder of the pressure vessel and then exits radially through openings into the bed, from where it flows outwards.

With regard to the further feature essential to the invention that the bed to be extracted is combined with an adsorption material, the invention provides as preferred representatives of at least one of the series activated carbon, aluminum oxide and / or silicon oxide, such as zeolites. The bed can be combined with the adsorption material selected in each case by homogeneous or heterogeneous mixing, by introducing the adsorption material in layers into the bed or by adding the adsorption material. It is preferred of the present invention if the adsorption material is introduced into the bed in layers or if it is connected downstream of the bed to be extracted.

Depending on the cork-containing material to be extracted or its ingredients, it may be advantageous if the compressed gas contains at least one entrainer or a co-solvent, such as water, C 1. ₅ alcohols, for example methanol, ethanol, propanol, isopropanol, butanols and pentanols, and ether. According to the invention, this should particularly preferably take place in amounts which are between 0.1 and 10% by weight, preferably between 0.5 and 8% by weight, more preferably between 2 and 6% by weight, even more preferably between 3 and 5% by weight, based on the amount of gas used.

Since the object of the present invention was to extract cork-containing material in such a way that the reduction of the undesirable contents and accompanying substances lead to food-grade products, the present invention also provides that organic compounds and preferably (chlorinated) phenols from the cork-containing material and / or (chlorinated) anisoles and here in particular pentachlorophenol (PCP), trichloroanisole (TCA) and / or tetrachloroanisole (TeCA) as well as waxes and fats are removed. The arrangement of the individual device modules for carrying out the claimed method steps is not to be regarded as restrictive for the present method, but the present invention provides a variant in which the method is carried out in at least one autoclave, a module arrangement being particularly preferred, where two pressure vessels are connected at least in series or in parallel.

The process arrangement usually consists in that two autoclaves connected in parallel or in series with the cork-containing starting material are subjected to the extraction gas. Any adhering waxes and fats are then separated in a downstream cyclone at low temperatures and the cyclic organic compounds are separated from the extraction gas in a third autoclave, which is filled with the adsorption material in the form of activated carbon.

With the proposed method, in particular due to the isobaric conditions and the radial or axial flow of the compressed extraction gas, an almost quantitative removal of the undesired organic cork ingredients takes place, so that the purified cork materials obtained can be safely used in the food industry.

The present invention thus relates to a process for the extraction of cork-containing material with the aid of a compressed gas at temperatures between 10 and 120 ° C and pressures between 10 and 600 bar, the extraction being carried out under isobaric conditions, the compressed gas being the bed radially or flows axially and the bed to be extracted is combined with an adsorption material. In this way it is possible, for example, to remove cork plates, cork granules, bottle cork or pressed cork from organic compounds, such as, for example, pentachlorophenol, trichloroanisole, tetrachloroanisole and waxes and fats, so that the cleaned ones cork-containing materials can be used without hesitation in the food sector and in particular in the beverage sector.

The following example illustrates the advantages of this method for the extraction of cork-containing material with the help of a compressed gas.

example

In this example, two autoclaves connected in parallel were each filled with 270 kg of a powdered cork material and then flowed through with a flow rate of 18 m ³ / h of supercritical CO ₂ isobar at a pressure of 120 bar and a process temperature of 60 ° C. The ratio of compressed gas to cork-containing raw material was 66: 1.

Subsequently, the extraction gas loaded with the compounds to be extracted was transferred to a cyclone cooled to 0 ° C., which was also operated isobarically and in which waxes and fats were separated from the extraction gas.

Finally, the extraction gas, which was now only loaded with the organic cyclic compounds, was passed into a downstream third autoclave, which was filled with 2 tons of activated carbon.

After one hour of absolute extraction time, the charged powdered cork material was freed quantitatively from the organic compounds PCP, TCA, TeCA as well as waxes and fats.

Claims

claims

1. Process for the extraction of cork-containing material with the aid of a compressed gas at temperatures between 10 and 120 ° C and pressures between 10 and 600 bar, characterized in that the extraction is carried out under isobaric conditions, that the compressed gas is the fill radial or axial flows through and that the bed to be extracted is combined with an adsorption material.

2. The method according to claim 1, characterized in that the cork-containing material is cork boards, cork granules, cork powder, bottle cork and / or pressed cork.

3. The method according to claim 2, characterized in that a cork-containing material is used, the mechanical and / or chemical and / or physical pretreatment, such as. a crushing step, an acid-base treatment or a cooking process.

4. The method according to any one of claims 1 to 3, characterized in that it is carried out at temperatures between 40 and 100 ° C and pressures between 100 and 150 bar.

5. The method according to any one of claims 1 to 4, characterized in that it is carried out at a weight ratio of compressed gas: cork-containing material from 1 to 100: 1.

6. The method according to claim 5, characterized in that it is carried out at a weight ratio of compressed gas: cork-containing material from 20 to 70: 1, in particular 40: 1.

7. The method according to any one of claims 1 to 6, characterized in that the compressed gas is used in the supercritical state.

8. The method according to any one of claims 1 to 7, characterized in that the bed is flowed through by the compressed gas radially from the inside to the outside.

9. The method according to any one of claims 1 to 8, characterized in that the bed to be extracted is combined with at least one adsorption material selected from the group consisting of activated carbon, aluminum oxide and silicon oxide, such as. Zeolites.

10. The method according to any one of claims 1 to 9, characterized in that the adsorption material is used in layers in the bed or downstream of the bed to be extracted.

11. The method according to any one of claims 1 to 10, characterized in that at least one entrainer or a co-solvent, such as water, Cι _-5 alcohols and ethers, is added to the compressed gas.

12. The method according to claim 11, characterized in that the entrainer or co-solvent is mixed in amounts between 0.1 and 10 wt .-% based on the gas content.

13. The method according to any one of claims 1 to 12, characterized in that from the cork-containing material organic compounds and preferably (chlorinated) phenols and / or (chlorinated) anisoles and particularly preferably pentachlorophenol (PCP), trichloroanisole (TCA) and / or tetrachloroanisole (TeCA) as well as waxes and fats are removed.

14. The method according to any one of claims 1 to 13, characterized in that it is carried out in at least one autoclave and preferably in at least two pressure vessels connected in series or in parallel.