WO2016198633A1

WO2016198633A1 - Method and device for removing or reducing nitrogen or sulphur compounds from liquid foodstuffs or precursors thereof

Info

Publication number: WO2016198633A1
Application number: PCT/EP2016/063346
Authority: WO
Inventors: Martin Schmitt; Volker Schneider
Original assignee: Martin Schmitt
Priority date: 2015-06-11
Filing date: 2016-06-10
Publication date: 2016-12-15
Also published as: DE102015109344A1

Abstract

The invention relates to a method for removing or reducing nitrogen or sulphur compounds which negatively affect smell and/or taste, from liquid foodstuffs or precursors thereof, said compounds diffusing through a membrane and being converted or adsorbed such that their diffusion back into the liquid foodstuff is prevented.

Description

Process and apparatus for removing or reducing nitrogen or sulfur compounds from liquid foods or precursors thereof

description

The invention relates to a process for the removal or reduction of nitrogen and / or sulfur compounds from liquid foods or precursors thereof, and to an apparatus for carrying out the process.

As with any organic product, wine is sometimes subject to strong fluctuations in quality and taste. An undesirable influence on smell, taste and appearance can result in high losses for the producer.

Weinfehler is a collective name for unwanted taste, smell or visual impressions in the wine.

These can either be produced during production (eg during fermentation), brought into the wine during storage (eg oxidation) or through external materials (eg cork faults). If the deficiencies are caused by microorganisms, they are called wine sickness. In addition to cloudiness, odor and taste defects due to microbiological metabolites and chemically induced color, odor and taste defects are of great importance. Thus Essignote or Lösungsmittelton can arise by the presence of acetic acid or ethyl acetate.

As a mousse is a rare occurring Fehlton called, reminiscent of ammonia and the smell of mouse harn. Although the cause has not been fully elucidated, heterocyclic nitrogen compounds such as acetylpyrroline (ACPY) are considered to be important causative agents. Further important causers are, in particular, two isomers of 2-acetyltetrahydropyridine, such as 2-acetyl-3,4,5,6-tetrahydropyridine, 2-acetyl-1,4,5,6-tetrahydropyridine, 2-ethyltetrahydropyridine and 2-acetyltetrahydropyridine. Acetyl-1-pyrrole.

An important class of flavorings in wine are derivatives of methoxypyrazine. Examples of such compounds are IBMP (2-isobutyl-3-methoxypyrazine) and IPMP (2-isopropyl-3-methoxypyrazine). Methoxypyrazines enter the wine from unripe grapes, but also from grape leaves or as secretions of certain insect-infested insects. This can lead to a grassy, vegetal taste and smell impression.

An error recently described is called an untypical aging sound (UTA). This can affect white wines already at a relatively young stage. Such wines are recognized in the smell of unwanted aroma notes after mothballs, naphthalene, acacia flowers, soap, washing powder or washing machine. In taste they have a disturbing de Bittere auf, are short on the finish and mostly of a pale color.

The essential impact substance responsible for UTA was identified as 2-aminoacetophenone (AAP), which is already detected in very small amounts of <1 μg / l. This error is particularly associated with drought stress on the plant during ripening, inadequate nutrient supply, high yield and inadequate grape ripeness. Because of global climate change, the importance of this error has taken to ^¬.

1 l yg / specified, wherein the detection threshold is fixed ^¬ Lich depending on the wine Matrix - as odor detection threshold for AAP is in white wines 0.5. The formation of AAP takes place predominantly chemically from the odorless precursor stage indole-3-acetic acid, which in turn represents a degradation product of the amino acid tryptophan.

So far there is no way to remove AAP from wines or to reduce the content.

Another mistake, the so-called "foxtone", is associated with methyl anthranilate, another aromatic amine, in wines derived from non-vinifera grape varieties, which are grown and marketed, for example, in the US and Canada This Foxton is even characteristic and is accepted by the consumer.

Other nitrogen compounds in the wine are biogenic amines, especially breakdown products of amino acids. They are predominantly formed by certain strains of bacteria, which in the wine spontaneous malolactic fermentation (transformation of malic acid into lactic acid), but also from fungi inhabiting rotten grapes. There are also wine defects caused by sulfur compounds. As Böckser a wine defect is referred to, which is caused by volatile, foul-smelling sulfur compounds such as mercaptans or hydrogen sulfide. The yeast can enzymatically reduce sulphite ions, which are introduced into the wine by sulfurization, into hydrogen sulphide, a substance with a typical smell of rotten eggs. This wine defect is found especially in young wines. If this is not recognized in time or even overlooked, it can develop into a so-called "Lagerböckser". This is due to various (in some cases not yet fully clarified) Fol ^¬ reactions to the formation of volatile sulfur compounds, in particular of ethyl and methyl mercaptan. The smell of such mercaptans is reminiscent of burned gum, garlic, rotten onions, rotten eggs, cooked cabbage, etc.

As a preventive measure against Böckser, the turbidity of the must should be removed as part of the must preclarification or yeast strains used for fermentation, which are characterized by a low propensity to form such volatile sulfur compounds. Already existing wine defects of this kind can be corrected by the addition of copper compounds or silver chloride.

However, such treatment of the wine is problematic because other builds character ^¬ teristics of the wine can be changed by the applied treatment agent. In addition, the legal regulations allow only very limited addition Such adjuvants, incidentally, later separated again ^¬ who must.

Especially nitrogen and sulfur compounds lead to very disturbing wine defects. In addition, UTA often occurs only during the maturation of the wine. At this time ei ^¬ ne treatment of wine is only very limited.

Although the causative agents of most wine defects are known, it is difficult to remove selected compounds from the wine without altering the sensory properties of the wine or leaving residues of the treating agent in it. Moreover, the addition of substances for fining is permitted only within narrow limits and also the subsequent separation of such additives can be difficult. It is often sufficient that the content of compounds causing wine defects is only reduced below their odor or taste threshold value. In addition to cations and anions, wine also contains a large number of organic molecules from the grape and the metabolism of the microorganisms involved in the vinification, which are of great importance for the taste, smell and appearance.

There are analytical procedures known to those organic ^¬ specific constituents can be extracted from an aqueous matrix, by offering them a hydrophobic medium in which they dissolve better. This medium can also be a hydrophobic solid. This is used, for example, to determine volatile organic compounds (VOCs). This is z. As one with polydimethylsiloxane (PDMS) coated stir bar introduced into a sample. ^{Depending on} their octanol-water partition coefficient, volatile organic compounds diffuse from the aqueous phase into the PDMS. For analytical determination, the adsorbed volatile compounds are then extracted from the PDMS, eg. B. by thermal desorption.

From viticulture methods are known to remove so-called volatile acid. US6913776 describes a process for the removal of undesirable substances from wine. In this case, volatile substances via a porous hydrophobic membrane (Po ^¬ lypropylen, polytetrafluoroethylene) transferred from the wine in an alcohol-containing extraction liquid. The Extraktionsflüs ^¬ sigkeit is purified via a circuit which may include exchange column a anion. The method is mainly used for the removal of volatile acid or ethyl acetate.

From Ferreira et al. Elseviers Science BV 2003; Chapter 8: Fereira et al., Membrane Aromatic Recovery System (MARS) - A new process for recovering phenols and aromatic amines from aqueous streams; pp. 165-181;) it is known that z. B. Aniline can be extracted from industrial wastewater by diffusion through a silicone membrane (0.5 mm thickness) in a highly acidic solution (pH below 1). Since large volumes are extracted, the pH is constantly updated.

The object of this invention is to provide a method for removing or reducing nitrogen and / or sulfur compounds from liquid foods or precursors thereof. solution

This object is achieved by the inventions having the features of the independent claims. Advantageous developments of the inventions are characterized in the subclaims. Of the

The wording of all claims is hereby incorporated by reference into the content of this description. The inventions also include all meaningful and in particular all-mentioned combination Nati ^¬ ones of independent and / or dependent claims.

The object is achieved by a process for the removal or reduction of basic compounds or sulfur compounds from liquid foods, comprising the following steps: a) contacting the food with one side of a hydrophobic membrane;

b) diffusion of the substances to be removed or reduced in and through the membrane;

c) Conversion and / or adsorption of the substances in such a way that diffusion of these substances back into the liquid food or the precursors thereof is excluded.

The reduction may also include a complete removal. Individual method steps are closer beschrie ^¬ ben. The steps need not necessarily be carried out in the angege ^¬ surrounded order, and the method to be described can also have further unspecified steps. Liquid foods or precursors thereof are liquids or liquids suitable for consumption, which are processed into such. These further steps can, for example, be dilution, filtration and / or fermentation processes. Examples of such liquid foods are fermented or unfermented fruit juices. This may be fruit juices which are directly suitable for consumption, or precursors from processing, such as must or concentrates. Further examples of ^such liquid foodstuffs are liqueurs or distillates.

In a first step, the foods or precursors thereof are contacted with one side of a hydrophobic membrane.

Hydrophobic membrane means that the material of the membrane is substantially water-insoluble and immiscible with water. Here, water-insoluble, meaning that the membrane or the material forming the membrane in water is less than 50 ppm, forthcoming Trains t less than 30 ppm, especially less than 10 ppm, is lös ^¬ Lich.

The membrane is preferably non-porous. By such a membrane ensures that only suffi ^¬ accordingly non-polar compounds may cross the membrane.

The material of the membrane must therefore have a suitable polarity in order to form a solution space for the compounds to be depleted. Such materials are also known from solid phase extraction (SPE) or solid phase microextraction (SPME).

The material can be adapted accordingly for the application. Materials which are already approved for USAGE ^¬ tion with foods are preferred. Examples are Membra ^¬ NEN on the basis of silicones (Polyoctylmethylsiloxan (POMS) Polydimethylsiloxane (PDMS)), N-vinylpyrrolidone, polyetherimides, polyimides, acrylates, methacrylates or copolymers thereof.

In order to achieve sufficiently selective extraction of the basic compounds and sulfur compounds, the polymers of the membrane preferably include heteroatoms such as oxygen or nitrogen. These may, for example, carbonyl groups, It ^¬ tergruppen, ether groups, amide groups, hydroxyl groups, amino groups may be included heterocycles. These can also be present as page groups. In that respect are also polar

Groups modified polyolefins such as polyvinyl alcohols, appro ^¬ net. Particularly preferred polymers are based on Sili ^¬ cones whose polarity can be very varied. Thus, copolymers of silicones with other polymers containing the aforementioned heteratoms or groups, such as ethylene glycol. Thus, polymers based on silicones or silicone copolymers are preferred.

Preference is given to membranes based on silicones, such as PDMS.

The surface of the membrane can also be treated to a certain hydrophilicity or hydrophobicity of the surface to preserver ^¬ th (plasma, UV treatment). This can facilitate diffusion of the compounds into the membrane.

The membrane may also contain up to 50 wt .-% additives, such as fillers.

The thickness of the membrane can be chosen differently. Preferred is a thickness of less than 2 mm, in particular less than 1 mm, for example 0.01 to 1 mm, in particular less than 0.8 mm or below 0.6 mm. Examples are thicknesses between 0.05 mm to 0.8 mm or 0.05 mm to 0.6 mm.

The thickness of the membrane is the rate-limiting parameter for the diffusion of the compounds.

After diffusion through the membrane, the diffused substances are converted and / or adsorbed. The conversion and / or adsorption takes place in such a way that a diffusion of these substances back into the liquid food or the precursors thereof is excluded. As a result, the diffusion through the membrane is maintained. In particular, the conversion and / or adsorption prevents the compounds from being able to diffuse back into the membrane. Thus, no equilibrium can be established between the external medium and the membrane. This promotes continuous diffusion. Through a conversion, it is not so important if the substance is only slightly from the Memb ^¬ ran in the inner compartment.

In one embodiment of the invention, the transformation comprises protonation. This protonates the basic compounds. Preferably, the protonation forms a positively charged group, for example, amino groups are converted into charged ammonium groups. As a result of this increase in their polarity, those compounds can no longer diffuse back through the hydrophobic membrane. This is achieved by having proton sources on the other side of the membrane. This may be an acid with a sufficient pKa. Examples are inorganic acids such as hydrochloric acid, Schwefelsäu ^¬ acid, nitric acid, phosphoric acid, or organic acids, be ^¬ vorzugt mono- or polyvalent carboxylic acids such as Zitronensäu ^¬ acid, tartaric acid, malic acid, stearic acid, acetic acid, formic acid, oxalic acid, benzoic acid, vinylogous acids such as ascorbic acid, sulfuric acid esters or sulfonic acids such as p-toluenesulfonic acid, phosphorous acid esters, phosphonic acids, or mixtures of these compounds. It can also be used salts which can still release protons, for example, hydrogen sulphates, Hydrogenpospha- te, dihydrogen, preferably alkali metals such as Nat ^¬ Ministry or potassium. The molar amount of protons which are provided by the proton source is preferably at least as large as needed for the protonation amount of the compound is needed, in particular at least twice as large. At least one excess is preferred by a factor of 10.

In the case of the liquid foods to be treated, the amount of substance to be reduced is usually determined before the method is used. Depending on which amount of substance is to be removed, the amount of at least required protons can be determined. Frequently, the content of substance to be removed should only be lowered below a certain value, namely the threshold of perception.

In particular, there are conditions in which protonation of the basic compounds takes place. These conditions can only in certain areas, eg. B. on the functional groups of the ion exchanger. If only small amounts of water and / or free hydroxyl groups are contained in the medium of the inner space, diffused Aro ^¬ maesters can beispiels-, a hydrolysis may also be avoided or reduced.

In a preferred embodiment of the invention, the proton source is a cation exchanger, in particular an acidic cation exchanger, wherein the ion exchanger is sufficient

Protons for the protonation of basic compounds should provide. The anchor groups of such ion exchangers include carboxylate groups, phosphate groups, sulfonate groups (sulfoethyl groups, sulfomethyl groups or sulfopropyl groups). It can ion exchangers with different matrices, for example based on polymers or cellulose, verwen ^¬ det, z. Styrene DVB or cellulose. Strongly acidic cation exchangers with sulfonate groups are preferred. The membrane ensures that the food has no contact with the proton source. This ^excludes direct influence of the food by the proton source. Such effective separation between food and proto ^¬ nenquelle thus allowing the use of agents whose di- rect contact with the food is excluded due to the legal requirements.

In addition, the conditions of the process can be very selectively adapted to the substance / substance group to be extracted.

Preferably of the liquid food to be removed basi ^¬ specific compounds nitrogen-containing compounds, and in particular are special amines or heterocyclic bases. Aroma ^¬ diagram amines such as 2-aminoacetophenone, or heterocyclic Ba ^¬ sen as pyrazines are preferred. Examples of such compounds are 2-aminoacetophenone or 2-methoxypyrazines, in particular MDMP.

In particular, the basic compounds to be reduced are present only in small amounts, in particular in concentrations of less than 10 mg / l. Surprisingly Ver ^¬ go for the treatment of liquids with such low concentra- tions of the invention was suitable.

In a further embodiment of the invention, thiophilic compounds are arranged on the inner side of the membrane. These are compounds, complexes or surfaces which react with sulfur-containing compounds, in particular with SH groups. These are preferably copper and / or silver compounds, in particular copper and / or silver ions. Sulfur compounds, particularly malodorous volatile or ^¬ ganic sulfur compounds diffuse through the membrane and form with the thiophilic metal compounds salts, ie, they are converted accordingly and thus immobilized. Thus, these sulfur compounds are removed from the food. The copper and / or silver ions, for example, by

Present and at least obtained by partial solution of the corresponding salts or precursor compounds. For this purpose, a corresponding salt solution can be present on the other side of the membrane. Alternatively, elemental silver or copper may be present, with the sulfur-containing compounds binding to the surface of the metal. Can be, me ^¬-metallic plates, grids, nets, chips or powders, for example. The copper and / or silver ions can also be present in a matrix, for example an organic or inorganic compound which has corresponding binding sites. The ions may, for example, be bound in an ion exchanger. Due to the higher affinity of the copper and / or silver ions for the sulfur compounds, they are still able to bind the sulfur compounds. Examples are matrices with polar groups, such as hydroxyl, amino or carboxylic acid groups. They may also be complex ligands, for example mono- or tridentate ligands, such as dicarboxylic acids, diamines, ethylenediaminetetraacetate or iminodiacetic acid.

Possible copper salts include copper chloride, fersulfat copper, copper hydroxide, copper (I) oxide, copper (II) oxide, Kup ^¬ fersalze of organic acids, preferably mono- or polyvalent carboxylic acids such as citric acid, tartaric acid, malic acid or stearic acid. The arrangement behind the membrane is particularly avoided that the metal compounds must be added directly to the wine. Thus, a later removal of possibly too much added copper and / or silver ions from the product becomes superfluous. So far, when using z. For example, be removed by a blue fining with wine, surplus copper, which requires complicated precipitations and filtrations and pulls the Pro ^¬ product quality affected.

The molar amount of copper and / or silver ions which can be made available for the reaction with the sulfur compounds is preferably at least as great as that which is necessary for the amount of compound to be removed. is required, in particular twice as large. Preference is min ^¬ least a surplus by a factor of 10th

In the case of the liquid foods to be treated, the amount of substance to be reduced is usually determined before the method is used. Depending on what amount is to be removed in substance, the amount of the Minim ^¬ least required copper and / or silver ions can be determined. Frequently, the content should only be lowered below a certain value, ie below the sensory perceptual threshold.

In particular, the sulfur compounds to be reduced are only present in small amounts, in particular in concentrations of less than 100 μg / L, and of less than 10 μg / L. Surprisingly, the process according to the invention was suitable for the treatment of liquids with such low concentrations.

On the inner side of the membrane, a polar medium is preferably also present.

The medium does not have to be an aqueous solution. Other media may also be used, for example, alcohols, glycols or polyols such as polyethylene glycols. Can be controlled by the Reaktivi ^¬ ty existing in the medium proton source or thiophi- len compound.

The medium on the inner side of the membrane is liquid to solid. It is not gaseous. It may be, for example, a liquid, a paste or a solid. In the liquid or paste solid bodies may be present, for. B. granules of an ion exchanger. The process can be carried out at various temperatures, for example at 5 to 30 ° C.

The process is preferably used at a pressure of less than 4 bar, in particular less than 3 bar, preferably without an elevated pressure.

The method preferably does not include a step of reduced pressure, such as pervaporation.

Preferably, the Kontenzentrationsunterschied caused by the conversion and / or adsorption or chemisorption is the driving force for the diffusion of target molecules from the Le ^¬ bensmittel through the membrane into the capsule.

The duration of the contacting can be chosen differently and also depends on the content and the chemical nature of the compounds to be reduced. It can be a contact for several hours to several days or weeks. The liquid food can be mixed during the ^¬ who.

In a preferred embodiment of the invention, the medium on the inner side is not actively agitated or pumped during the process. It is preferably static. This allows the process to work without expensive equipment. However, it is possible that the liquid food is mixed during the period of contact with the membrane. It is also possible that the medium is guided on the inner side as an extraction circuit, and for example via the cation exchanger or bound copper and / or silver compounds is cyclized.

During the process, the decrease in the compounds to be reduced can be controlled. If a corresponding content in the liquid food or precursor thereof is achieved, the contacting of the membrane with the life ^¬ agent or precursor is terminated.

The method can be applied to different liquid foods or precursors thereof. Fermented or unfermented fruit juices are preferred on the basis of wine grapes ^¬, preferably with a base of grapes to the extent of at least 50 vol .-%. Fruit juices are preferred in the context of the production of wine. This may be the unfermented grape must or the fermented grape must.

Particularly preferred is the application to fermented fruit juices based on grapes. Especially through the fermentation process and storage, the substances to be reduced by the method according to the invention can be formed.

The invention also relates to a device for carrying out the method according to the invention.

The invention also relates to an apparatus for removing or reducing basic compounds or sulfur compounds from liquid foods or precursors thereof, which comprises at least one inner compartment and at least one membrane, wherein at least one membrane is arranged so that diffusion through this membrane between an inner compartment Compartment and a device surrounding the medium possible wherein the surrounding medium is the liquid food or a precursor thereof.

There is no mixing of the inner compartment and the liquid food or precursor thereof. There is only a mass transfer by diffusion through the boundaries of the inner compartment, in particular by the at least one membrane. In at least one inner compartment, means for Umwan ^¬ spindles and / or for adsorption of the compounds present, the device can be so placed in a medium containing the to-reducing substances that over Minim ^¬ least a membrane diffusion of compounds takes place in at least one inner compartment, wherein the compounds are converted or adsorbed in the inner compartment.

In one embodiment of the invention, the means for converting or adsorbing the compounds are selected from at least one proton source or at least one thiophilic compound. Preferably, the compositions are as for the process be ^¬ wrote.

The device may also comprise several compartments, each with different means.

In a preferred embodiment, at least one proton source is present in the inner compartment. In this case, the device is one for removal or reduction of nitrogen compounds. Preferred proton sources are described for the method. In a further preferred embodiment, at least one thiophilic compound, in particular at least one copper and / or silver compound, is arranged in the inner compartment. Preferred such compounds are described for the method.

In one embodiment of the invention, the volume of all internal compartments of the device is less than 1/100 of the volume of the food to be contacted.

In one embodiment, the membrane constitutes at least 20% of the inner surface of all inner compartments.

Hydrophobic membrane means that the material of the membrane is essentially water-insoluble and immiscible with water. Water-insoluble means that the membrane or the material forming the membrane in water is less than 50 ppm, preferably less than 30 ppm, in particular less than 10 ppm. is lös ^¬ Lich.

The at least one membrane is preferably non-porous. The mass transfer through the membrane takes place only by diffusion through the material of the membrane.

By such a membrane ensures that only suffi ^¬ accordingly nonpolar compounds pass through the membrane.

The material of the membrane must therefore have a suitable polarity in order to represent a solution space for the compounds to be reduced. Such materials are known from solid phase extraction (SPE), solid phase microextraction (SPME) or stir bar sorptive extraction (SBSE). The material can be adapted according to the application ^¬ the. Preferred are materials which are approved for use with food. Examples are membranes based on silicones (polyoctylmethylsiloxane (POMS), polydimethylsiloxane (PDMS)), N-vinylpyrrolidone, polyetherimides, polyimides, acrylates, methacrylates or copolymers thereof.

In order to achieve sufficiently selective extraction of the nitrogen and sulfur compounds, the polymers of the membrane preferably include heteroatoms such as oxygen or nitrogen. These may, for example, be converted into carbonyl groups, ester groups,

Ether groups, amide groups, hydroxyl groups, amino groups, hetero cycles be included. These can also be present as page groups. Insofar, polyolefins modified with polar groups, such as polyvinyl alcohols, are also suitable. Particularly preferred polymers are based on silicones, which Po ^¬ larity may very well be varied. So also Copolymer ^¬ re silicones can with other polymers, which contain the above-mentioned hetero atoms or groups, such as ethylene glycol. Thus, polymers based on silicones or silicone copolymers are preferred.

Preference is given to membranes based on silicones, such as PDMS.

The membrane may also contain up to 50 wt .-% additives, such as fillers. The thickness of the membrane can be chosen differently. Preferred is a thickness of less than 2 mm, in particular less than 1 mm, for example 0.01 to 1 mm, in particular less than 0.8 mm or less than 0.6 mm. Examples are thicknesses between 0.05 mm to 0.8 mm or 0.05 mm to 0.6 mm.

The thickness of the membrane determines the speed of diffusi ^¬ on the volatile compounds. If multiple membranes are present, not all must be the same material. Preferably, all membranes are made of the same material.

The device can be designed very differently. In one embodiment, the device is designed as a hollow body whose outer walls at least partially comprise a erfin ^¬ tion proper membrane. The interior of the hollow body ent ^¬ speaks the inner compartments. The hollow body can be cylindrical, cube-shaped, cuboidal, flat or irregular. Depending on the type of use, it does not have to be completely closed, as long as it is ensured that when it is used, the liquid food can not get into the ^inner compartment. The device may comprise means for opening and closing the hollow body. This allows the replacement and / or renewal of the contents of the inner compartments or the inner compartments depending on the usage. This can be at ^¬ play, a screw or clamp connection. In addition to the at least one membrane, the boundary walls of the device which form the inner compartment may be from ^¬ be arbitrary materials which are approved for use in liquid foodstuffs. These can be plastics, glass or metallic materials.

The internal volume of the device is preferably at least 100 times less than the volume of the liquid food or precursors thereof to be treated.

In another embodiment of the invention, the device in the inner compartment comprises an ion exchanger, wherein the material of the membrane has been applied to at least part of the surface of the ion exchanger. The ion exchanger can additionally be applied to a carrier material. The material of the membrane on the surface of the ion exchanger simultaneously forms the membrane. The Ionenaus ^¬ exchanger fills the inner compartment completely. Such a device can be obtained, for example, by enclosing ion exchangers, preferably in the form of granules, with the material of the membrane. Such granules can be added to the liquid food in a simple manner and removed again by filtration or sedimentation.

For applying the ion exchanger on a support, the ion exchanger is preferably applied to a support, which consists for example of a planar flat body made of a flexible material, and coated the carrier with ion exchange with the membrane-forming material, coated or laminated. In this way, surfaces can be obtained which have the desired effect. The device according to the invention is preferably completely or at least partially introduced into the liquid food to be cleaned. This means that at least part of the membrane is contacted with the liquid food.

In one embodiment, the device is designed as a completely insertable into the liquid food capsule.

As a result, devices with a specific capacity of compounds to be reduced can be obtained, for example. Depending on the amount of compound to be reduced, the number and duration of application of the capsules can be determined. In such an application, no filtration or pumping of the liquid food is necessary, which can often lead to quality losses.

In a further embodiment of the invention, the device comprises as acidic cation exchanger correspondingly modified cellulose, for. B. with sulfonyl or phosphoryl groups, which is ^¬ with the material of the membrane, for example, PDMS, ^¬ coated. This construction allows the construction of areal cation exchangers, which can be easily introduced into the liquid to be ^treated . Thus, a sheet of cellulose, for. B. blotting paper, are functionalized to an acidic ion exchanger and coated with the appropriate membrane.

Further details and features will become apparent from the following description of preferred embodiments

Connection with the subclaims. In this case, the respective features can be used alone or in combination be realized with each other. The possibilities to solve the problem are not limited to the embodiments. For example, area information always includes all - not mentioned - intermediate values and all imaginable subintervals.

The embodiments are schematically Darge ^¬ up in the figures. The same reference numerals in the individual figures designate the same or functionally identical or with respect to their functions corresponding elements. In detail shows:

FIG. 1 shows the UV-VIS absorption of the various samples; FIG.

Fig. 2 Schematic representation of the method according to the invention procedural;

Fig. 3 Schematic representation of the conversion of amines by protonation;

Fig. 4 Schematic representation of a Memb ran invention with ion exchanger; and

Fig. 5 Schematic representation of an embodiment of the invention;

Fig. 6 Schematic representation of an embodiment of the invention;

Fig. 7 Schematic representation of an embodiment of the invention.

FIG. 2 shows a schematic sequence of the method according to the invention. First, the membrane with the liquid medium is contacted life ^¬ 100. This results in the diffusion of the substances to be reduced through the membrane 110. These are converted accordingly, after passing through the membrane or ad sorbed ^¬ 120th FIG. 3 shows a schematic representation of the conversion of amines by protonation. The amines _(R-NH2) in the outer ^¬ Me dium, ie the liquid food 210 diffuse into the membrane 200 and through the membrane into the inner compartment 220. There, they are protonated to R- ⁺ H. ₃ Charged Ammoniumio ^¬ nen can not diffuse back into the membrane and are therefore removed from the equilibrium between the inner compartment and Memb ^¬ ran. This promotes the diffusion of other amines from the outer medium into the membrane.

Figure 4 shows a schematic representation of the process of un ^¬ ter using an ion exchanger. The connections

(Nitrogen and / or sulfur compounds) diffuse from the external medium 210 in the diaphragm 200. On the other sides of the membrane te in the inner compartment 220 is a Ionenaustau ^¬ shear 230 arranged. This may be an acidic cation exchanger in the case of the nitrogen compounds to protonate the nitrogen compounds. In the case of sulfur compounds, it may be a copper ion-loaded ion exchanger.

FIG. 5 shows a cross section through an embodiment of the device according to the invention. This comprises an outer wall 300 and at least one membrane 310. These enclose an inner compartment 320. In this compartment, an ion exchanger 330 can be arranged. The inner compartment is fully closed ^¬ constantly, so that a mass transfer can take place only by diffusion. Such a device can be completely surrounded by the medium to be cleaned, or be introduced into this in a simple manner.

FIG. 6 shows a further embodiment. In this case, an interior 420, or even a carrier material such as an ion exchanger, completely covered by a coating 420. This coating is also the membrane. In this embodiment, the device resembles a coated granule. This in turn can be easily introduced into the medium to be cleaned.

FIG. 7 shows in FIGS. A) to d) an embodiment of the invention. In this case, the device 500 is designed as a flat body similar to a sheet. This can, for example, be rectangular, as shown in a). However, the shape can be adapted ent ^¬ talking use, b) shows a cross section through this embodiment. Here, 510 shows the Memb ^¬ ran and 520 the interior, which is preferably filled in this case with an ion exchanger. Preferably, the ion exchanger is a cellulosic sheet modified as an acidic ion exchanger. The sheet 520 is coated on both sides with the material of the membrane 510, in c) it is shown that the material of the membrane 510 preferably envelops the entire sheet 520. This type of device, to a very large surface area for diffusion and can be easily Herge ^¬ provides. As shown in d), the capacity can be easily increased by using several sheets 540 side by side. As a result, the capacity of the device can be easily adapted to the application.

Examples

1.1 Encapsulated ion exchanger

From a PDMS monomer mixture, thin films having a thickness of 0.1 to 0.3 mm were cast. With such a movie was an annular piece of a silicone tube (1.5 cm ^{diam ¬} ser, length 8 mm) closed on one side. In the resulting cavity, a cation exchanger (in H ⁺ form) was filled and the open end of the silicone tube also sealed with one of the cast films. Thus, a drum-shaped cylinder was obtained, which has a membrane according to the invention on both sides. The inner compartment is formed by the silicone tube and the two membranes. A mass transfer outside - inside is only possible by diffusion, especially through the membrane.

A capsule so formed was placed in a model wine (500 mL) containing 2-AAP (100 mg / L). The content of 2-AAP was analyzed daily (UV-Vis spectroscopy at 362 nm, the main absorption of 2-AAP, PCIE). The control used was a capsule filled with Na.sup. ⁺ Ion exchangers and a sample without addition of a capsule (Control). The precisely measured ^¬ NEN values shown in Figure 1. It is clearly evident that significantly decreases only when the capsule with ion exchanger in the H ⁺ form (PCIE, poly- mer coated ion exchange) the content of 2-AAP.

1.2. Sodium bisulfate

NaHSC and glycerol (propane-1,2,3-triol) were triturated to a pasty crystal pulp and filled in place of the ion exchanger in a capsule analogous to Example 1. This capsule was placed in a solution of 2-AAP and the vessel sealed airtight. After about 10 days, any odor of 2-AAP had disappeared over the solution.

2.2. Removal of thiols The under 1.1. The capsule described above was filled with a Cu-loaded IDA ion exchanger and added to a "chunky" wine, and after a short time it was no longer possible to detect the wine error organically and no copper ions could be detected in the wine.

2.3. Encapsulation on Carrier A strip (1 x 5 cm) of a nonwoven fabric was coated with a Cu ²⁺ -loaded IDA ion exchanger (see 2.2.) And completely coated with PDMS. To 100 ml of a dry white wine was added approximately 10 mg of NaS nonahydrate with one drop of 2M HCl. There was a distinct smell of H ₂ S. In this mixture the pressure applied to the carrier verkapsel ^¬ te ion exchanger was added and the vessel was sealed. Within a week, the bright blue of the ion ^¬ exchanger changed into a brown-black, while the smell of hydrogen sulfide significantly decreased.

2.4. Removal of sulfur compounds

Squares were cut 5 x 4 cm from PDMS films (Elastosil film, Wacker Chemie) with a thickness of 100 ym and 200 ym. One piece of both thicknesses was joined on three sides by means of a silicone adhesive (Elastosil 43, Wacker). Over the remaining open side of the active substances (Ta ^¬ beauty 1; 500 mg) were introduced by means of funnels. Subsequently, the still open 4th side was closed with the mentioned silicone adhesive. All resulting silicone pouches were visually rigorously checked for any leaks. Also, the outside surfaces were very careful with each a method tailored to the appropriate filling method of any adhering active substance cleaned.

Each 300 ml bottles were filled with an inert gas, each filled with a silicone bag and filled with a synthetic test wine (spiked with H2 S and Et-SH per 10yg / liter) so that no headspace was created. The bottles were sealed with screw cap and the absence of AIR SUPPLY ^¬ occurs stored for 24 hrs.. After this period, aliquots of the samples were analyzed for their content of added SH compounds by GC / MS.

As a control, was added ^¬ sets (positive control) and a Silikonbeutelchen without Ak ^¬ tivstoff (negative control) instead of a Silikonbeutelchens CU SC. The values in the table indicate the effectiveness of the removal of the substance in% relative to the original amount, 90% represent a 90% removal of the substance (the values are averages of two measurements). Although the metallic actives appear less effective, they were measured only for 24 hours.

Table 1

Active substance H ₂ S [%] EtSH [%]

CUSO ₄ (positive control) 100 100

Negative Control 6, 0 13.2

Copper powder 79, 3 76, 5

Cu complex with iminodiacetic acid 88.3 87.5

Cu-loaded immobilized imino ^¬ 99, 7 95, 2 diacetic acid

Copper foil 38, 6 65, 1

Cu I oxide 96, 2 93, 1

Cu II stearate 91, 9 90, 9

Silver powder 34, 0 64, 00

Silver acetate 99, 2, 97, 00

Cation exchanger, saturated with 96, 0 96, 9 silver ions

Claims

claims

A process for removing or reducing basic compounds or sulfur compounds from liquid foods or precursors thereof, comprising the steps of:

a) contacting the food or precursors thereof with one side of a hydrophobic membrane;

c) Conversion and / or adsorption of the substances on the inner side of the membrane in such a way that diffusion of these substances back into the liquid food or the precursors thereof is excluded.

2. The method according to claim 1, characterized in that the membrane is not porous.

3. The method according to any one of claims 1 or 2, characterized in that on the inner side of the membrane, a pola ^¬ res medium is present.

4. The method according to any one of claims 1 to 3, characterized in that the conversion of the compounds comprises a protonation.

5. The method according to any one of claims 1 to 4, characterized in that on the inner side of the membrane a Katio ^¬ nenaustauscher is arranged.

6. The method according to any one of claims 1 to 5, characterized in that the basic compounds to be reduced are nitrogen-containing compounds.

7. The method according to any one of claims 1 to 3, characterized in that thiophilic compounds are arranged on the inner side of the membrane.

8. The method according to claim 7, characterized in that the compounds are copper and / or silver compounds.

9. Apparatus for carrying out the method according to one of claims 1 to 8.

10. An apparatus for removing or reducing basic compounds or sulfur compounds from liquid foods, which comprises at least one inner compartment and at least one membrane, wherein at least one membrane is so angeord ^¬ net that via this membrane diffusion of the compounds to be reduced between an inner Compartment and a medium surrounding the device is possible, wherein the surrounding medium is the liquid food or a precursor thereof, wherein the compounds in the inner compartment are converted and / or adsorbed there by means for converting and / or adsorption present.

11. The device according to claim 10, characterized in that the means for converting or for adsorption are selected from at least one proton source or at least one thiophilic compound.