EP3745879A1

EP3745879A1 - Device for the electroporation of foods with protection against deposits

Info

Publication number: EP3745879A1
Application number: EP19700572.1A
Authority: EP
Inventors: Stefan Toepfl; Julian Witt; Claudia Siemer
Original assignee: Elea Vertriebs Und Vermarktungsgesellschaft Mbh
Current assignee: Elea Service GmbH
Priority date: 2018-01-31
Filing date: 2019-01-10
Publication date: 2020-12-09
Also published as: WO2019149491A1; DE102018201498A1

Abstract

The invention relates to a device (1) for the treatment of media, in particular the electroporation of foods, comprising a treatment chamber (2) for receiving the medium to be treated and at least two electrodes (10) for generating an electrical field in the treatment chamber (2). So that the device guarantees a homogeneous electrical field and less contamination occurs, the device according to the invention also comprises at least one protective means (4) for protecting against deposits of the medium on a contact surface (5) of the device (1) coming into contact with the medium.

Description

Device for the electroporation of food with a protection against

deposits

The present invention relates to a device for the treatment of media, in particular for electroporation of foods, comprising a treatment chamber for receiving the medium to be treated and at least two electrodes for generating an electric field in the treatment chamber.

It is known to treat foods with an electric field, for example, to improve the shelf life of foods by perforating the cell membranes of harmful microorganisms by the electric field and thereby killing the microorganisms. In the treatment of a foodstuff with an electric field, especially protein-containing products containing egg whites, egg yolk or whey proteins, undesirable protein denaturation and so-called fouling, in which unwanted residues form, may occur.

The undesirable residues pollute the treatment apparatus, contaminate subsequent media and adversely affect the proper use of the apparatus because they interfere with the formation of the homogeneous electric field.

It is therefore the object of the present invention to provide an improved device for the treatment of media, in particular for the electroporation of foods, which ensures a homogeneous electric field and reduces contamination of the device. The device mentioned above solves this problem by at least one free holder for protection against deposits of the medium at a coming into contact with the medium contact surface of the device.

The free holder, a structure or an element which prevents the adhesion of substances of the medium preventive and / or already existing deposits removed from the contact surface, ensures that no unwanted residues in the device, for example in a part of the treatment chamber or Deposits on surfaces of the electrodes, which could lead to pollution or could adversely affect the homogeneity of the generated electric field.

The invention can be further improved by means of the following developments, which are advantageous in each case and can be combined with one another as desired, and advantageous embodiments. Electroporation results in the reversible or irreversible permeabilization of the cell membrane and can be used, for example, to kill microorganisms in a foodstuff. The electroporation of foods can be achieved particularly effectively by connecting the at least two electrodes to a pulse generator. In this case, different electrode shapes can be used, for example plate, ring, grid, hollow or flow electrodes. As a pulse generator, a high-voltage pulse generator can be used, for example a Marx generator which generates electric fields in the form of short pulses in the micro-to millisecond range of a high voltage in the kilovolt range. The electrodes can be arranged parallel, coaxial, collinear, conical or as an annular gap. The distance between the electrodes, the electrode spacing, can be both fixed and variable. In annular gap electrodes, one electrode is designed as a pipe section and the other electrode as an electrode plate. The electrode plate is arranged at an end face of the tubular electrode, spaced therefrom. The distance between the front side of the ring or tube electrode from the electrode plate corresponds to the electrode spacing, which in this embodiment can easily be variably adjusted by making the two electrodes displaceable relative to one another. Even with a conical electrode in which both the inner electrode and the outer electrode are both conical, a variable electrode spacing can be achieved, provided that the two conical electrodes are arranged displaceably relative to one another along the axis of rotation. Coaxial and collinear electrode arrangements preferably have a fixed electrode spacing.

According to one embodiment, at least one electrode can form a wall section of the treatment chamber. For example, two plate electrodes can form opposing walls of the treatment chamber. It is also possible to provide a ring or tube electrode as a lateral boundary and thus a wall section of the treatment chamber.

In order to ensure a continuous treatment of the medium, the treatment chamber may have an inlet opening and an outlet opening spaced therefrom. The chamber may, for example, constitute a flow chamber into which medium is continuously introduced and a corresponding quantity of the medium is re-exported elsewhere. Possible embodiments are, for example, a treatment chamber, which is formed by a pipe or a pipe section, which is advantageous and can be implemented in a simple manner, in particular for the treatment of flowable media. A "free holder" in the sense of the present invention is an element or component of the device which preemptively suppresses deposits of the medium on a contact surface of the device which comes into contact with the medium, for example a part of the treatment chamber or an electrode surface, that is Prevents sedimentation from the outset, and / or subsequently removes existing deposits.

According to one embodiment, a surface coating on the contact surface may form the free holder. The surface coating is adapted to the corresponding contact surface of the device on which it is applied. If the surface coating is applied to a part of an electrode, then this coating must be electrically conductive in order not to influence the formation of the electric field. If the surface coating is formed on an electrically insulating contact surface, then the surface coating is likewise to be designed to be electrically insulating. The surface coating may be a non-stick coating or have anti-adhesive properties. In order to prevent deposits of denatured proteins, the surface coating may preferably consist of a hydrophobic material. Hydrophobic materials reduce the adhesion of denatured food components and preventively prevent the formation of a deposit of these undesired degradation products. Hydrophobic surface coatings are those that are water-repellent, ie where water drips off. Hydrophobic surfaces have a water contact angle of more than 90 °, wherein the contact angle can be measured, for example, with a contact angle goniometer.

In another embodiment, the free holder may include a scraping element for scraping deposits on the contact surface. By means of such a stripping element, deposits already formed can be subsequently removed again from the contact surface. The scraper should have sufficient strength to remove the deposits but at the same time not be so hard as to damage the contact surface with which it comes into contact. The stripping element can for example be made of rubber or a plastic with corresponding properties.

According to a further embodiment, the stripping element can be arranged on an electrode, which is advantageous in that the surface of electrodes, which come into contact with the medium, are particularly susceptible to deposits, and the stripping element is thus in the immediate vicinity can place to the contact surface. The scraper can extend from one electrode to the corresponding other electrode and thus bridge and cover the entire space along which the field lines of the applied electric field run. The wiping element can be designed to be movable relative to the contact surface, which is advantageous in that it accomplishes the scraping movement of the wiping element along the contact surface. At the same time, the stripping element can form a movable mixing tool for mixing the medium, which leads to a particularly uniform introduction of energy into the medium.

The stripping element can be connected in a torsionally rigid manner to a rotating shaft. The rotatable shaft can be arranged in the treatment chamber and be formed, for example, from an insulating material, that is to say be an insulator. The shaft can also be formed by a rotatable Elekt rode. In addition to a rotatable shaft located centrally in the treatment chamber, a rotatable outer shaft, for example a hollow shaft which forms a pipeline or a pipe section, can also be connected in a rotationally rigid manner to the stripping element. Of course, the combination of a rotatable inner shaft as well as rotatable outer hollow shaft is conceivable.

As already mentioned, one of the electrodes can form the rotatable shaft. Thus, embodiments are possible in which one of the electrodes is rotatable relative to another, fixed electrode. On at least one of the two electrodes, the stripping element can be arranged, which then moves relative to the other electrode, be it with the rotatable electrode on the fixed electrode or that the rotating electrode is guided along the fixed stripping element. Also possible are embodiments with two stripping elements, one of which is arranged on the fixed and the other on the rotating electrode.

According to a further embodiment, the device according to the invention may further comprise a turbulent mixer for generating a turbulent mixing of the medium in the treatment chamber. Such a turbulent mixer generates a turbulent flow in the treatment chamber, which leads to a particularly good mixing. Turbulence avoids over-treatment and undesired degradation of the treated medium at the interface between the device and the medium due to a lower flow rate, such as occurs with a laminar flow. A turbulent flow profile is thus advantageous because it reduces the boundary layer thickness, which minimizes the deposition of material potentially adhering to a surface. A turbulent mixer thus constitutes another possible embodiment of a free-holder in the sense of the present invention. The turbulent mixer may include a static mixer, turbulators, a turbulence generator, and / or moving components. Turbulence can be effected passively by special shapes, such as in static mixers or by turbulators or turbulator structures. Static mixers, also known as static mixers, are devices for mixing fluids that have no moving elements but flow-influencing elements. The flow-influencing elements divide the flow of material, twist the flows and bring them together again. These elements can be helical, lamellar or even grid-shaped. A turbulator or turbulator structure is understood to mean a surface disturbance which swirls a laminar boundary layer flow and converts it into a turbulent flow. Examples of turbulator structures are dimples on a surface, as found for example in golf balls, or rails running transversely to the flow direction or small vertical sheets or holes, as can be found, for example, on ailerons of sailplanes or wind turbines. A passive turbulence mixer can be arranged on the free holder. Thus, for example, a surface coating which forms a free holder may be provided with turbulators.

In addition to such passive turbulent mixers as static mixers or turbulators, active turbulent mixers, for example turbulence generators and / or moving components, are also possible. For example, an ultrasonic generator or a vibrator which vibrates certain areas of the apparatus may be provided as a turbulence generator. In a further embodiment, a gas inflow device can be provided as a turbulent mixer, through which a gaseous medium is introduced into the treatment chamber via the contact surface. For example, rows of fine holes may be provided on the contact surface, through which air can be injected transversely to the flow direction.

Movable parts may, for example, be mobile mixing tools, such as blade, turbine or screw mixers, or else movable containers, for example drum mixers or cone mixers.

In one embodiment, the free holder forms an element of the turbulent mixer. For example, a stripping element that is designed to be movable relative to the contact surface may be a mixing tool of a turbulent mixer, as well as, for example, a rotatable hollow shaft as the outer electrode or a rotatable inner electrode located in the treatment chamber. In the following, the invention will be explained in more detail by way of example with reference to advantageous embodiments with reference to the drawings and the following experimental examples. The advantageous further developments and configurations shown here are each independent of each other and can be combined with one another as required, depending on the application.

Show it:

1 shows an exemplary embodiment of the device according to the invention for treating media, in particular for the electroporation of foods in a schematic representation in longitudinal section; Fig. 2 shows an exemplary further embodiment of a device according to the invention in

Longitudinal section (left) and in cross section (right);

Fig. 3 shows an exemplary further embodiment of a device according to the invention in

Longitudinal section (left) and in cross section (right);

Fig. 4 shows an exemplary further embodiment of a device according to the invention in

Longitudinal section (left) and in cross section (right); and

Fig. 5 is a schematic representation of another embodiment of the invention

Device in longitudinal section.

A device 1 for the treatment of media, in particular for the electroporation of foodstuffs in a first embodiment, is shown by way of example in FIG. The apparatus 1 shown in FIG. 1 comprises a treatment chamber 2 for receiving the medium to be treated, at least two electrodes 10 for generating an electric field in the treatment chamber 2, and at least one free holder 4 for protection against deposits of the medium on one The treatment chamber 2 delimits a treatment space 6, which is accessible via an inlet opening 7 and an outlet opening 8. The inlet opening 6 is arranged on one side of the treatment chamber 2 and the outlet opening 8 is spaced from the inlet opening 7 and arranged on the side of the treatment chamber 2 opposite thereto. The treatment chamber 2 is designed as a flow chamber 9 in the embodiment shown and designed for the continuous treatment of medium with an electric field in the treatment room 6. In FIG. 1, the arrows in the region of the inlet opening 7 and outlet opening 8 signal the direction of flow of the medium through the chamber 9.

In the embodiment shown, two electrodes 10 are connected via energy lines 1 1 to a voltage source 12, in the embodiment shown a pulse generator 13. The two electrodes form a capacitor 3 for forming an electric field in the treatment chamber 6. In the embodiment shown, the two electrodes 10 are formed of electrode plates which are arranged parallel to each other and thus form parallel walls of the treatment chamber 2, which the treatment space. 6 limit themselves to opposite sides. In the embodiment shown, the electrodes 10 thus form a wall section 14 of the treatment chamber 2.

In such an electrode arrangement, a homogeneous electric field for uniform media treatment can be produced. For example, a high-voltage pulse generator, such as a Marx generator, can be used as the pulse generator 13, with which electrical pulses of a high voltage in the kilovolt range and a short duration in the micro-to millisecond range can be generated.

The surfaces of the device 1 pointing into the treatment chamber 6 of the treatment chamber 2 come into contact with the medium 1 to be treated and thus form contact surfaces 5. When an electric field is generated in the treatment chamber 2 and the corresponding treatment of the medium, denaturation, for example of proteins of a foodstuff, can take place, which can deposit on a contact surface. Such deposits are undesirable because they pollute the device 1 and adversely affect the desired homogeneity of the generated electric field.

The present invention therefore provides a free holder 4 for protection against deposits of the medium, which is arranged on a contact surface 5.

In the embodiment of FIG. 1, a surface coating 15 on the contact surface 5 forms the free holder 4. The surface coating 15 may be formed as an anti-adhesion coating for the potentially unwanted deposits. In the treatment of foodstuffs, the adhesion of deposits, in particular in the form of degraded proteins, can be avoided by rendering the surface coating 15 hydrophobic, since most of the undesired degradation products are repelled by a hydrophobic surface. So can on a simple way a preventive, preventive protection for the suppression of deposits on the contact surface 5 can be achieved.

The apparatus 1 in the embodiment shown in Fig. 1 further comprises a turbulent mixer 16 for generating a turbulent mixing of the medium in the treatment chamber 2. The turbulent mixer 16 is another free holder 4. It reduces the thickness of

Boundary layer between contact surface 5 or surface coating 15 and the medium in the treatment chamber 2. As a result, the flow rate of the medium increases along the contact surface 5, which reduces the risk of deposits and can rinse off already existing deposits from the contact surface 5. Due to the turbulent flow generated by the turbulent mixer 16, a nearly constant flow velocity of the medium in the entire treatment chamber 6 prevails. This promotes a homogeneous mixing of the medium and allows a uniform energy input without unwanted Energiespe- zen in certain areas of the treatment chamber 2, where the medium flows slower and thus treated longer. The turbulent mixer 16 of Fig. 1 is a passive mixer with no moving parts. In the embodiment shown, the turbulent mixer 16 comprises turbulators 17 in the form of so-called dimples 18, which lead to a tearing off of a laminar flow profile at the contact surface 5 and to turbulences and thus turbulences.

An alternative embodiment of a passive turbulent mixer would be for example a so-called static mixer, which could be arranged in the treatment space 6.

A turbulence generator, for example an ultrasound generator or in a vibrator (not shown) or a turbulent mixer with moving parts, which will be discussed below, can also be used to produce a turbulent mixing in the treatment chamber 2. 2, a further embodiment of the device 1 according to the invention is shown. In Fig. 2 and in all subsequent figures, the same reference numerals are used for elements whose function and / or structure is similar to elements of one of the previous embodiments.

The treatment chamber 2 of the further embodiment from FIG. 2 is likewise designed as a flow chamber 9 with an inlet opening 7 and an outlet opening 8. In contrast to the treatment chamber 2 of FIG. 1, the treatment chamber 2 of FIG. 2 is provided with an annular treatment space 6. The electrodes 10 of the embodiment of Fig. 2 comprise a Outer electrode 19 and an inner electrode 20 which are arranged coaxially with each other and between which an annular treatment space 6 extends. Both the inner electrode 20 and the outer electrode 19 form with their directed into the treatment chamber 6 Zylin derflächen wall sections 14 of the treatment chamber 2 from. The outer electrode 19 is formed as an electrode tube. The inner electrode 20 may be formed both as a tube electrode and as a rod electrode, wherein the longitudinal axes L of the two rotationally symmetrical electrodes 19, 20 coincide, so that they are arranged coaxially.

Between the electrodes 10 of the embodiment of Fig. 1 as well as the electrodes 10 of the embodiment of Fig. 2, there is a constant, fixed electrode spacing, which contributes to the generation of a homogeneous electric field.

In the embodiment of FIG. 2, the treatment chamber 2 is formed by pipe sections of the pipe-shaped electrodes 10, the inlet opening 7 being arranged on one side of the pipe section and the outlet opening 8 on the opposite end side of the pipe section. Thus, the medium can flow continuously through the treatment space 6 located in the pipeline section (the direction of flow of the medium in the region of the inlet opening 7 and outlet opening 8 is indicated by arrows in FIG. 2).

In contrast to the embodiment of FIG. 1, the device 1 of the embodiment according to FIG. 2 as a free holder 4 has a stripping element 21 for scraping off deposits on the contact surface 5. The stripping element 21 may for example consist of rubber or a plastic with insulating properties, which corresponds to rubber in terms of hardness and elasticity.

In the embodiment of FIG. 2, the stripping element 21 is arranged on an electrode 10, namely the outer electrode 19. By way of example, the stripping element 21 is fastened to the contact surface 5 of the outer electrode 19 and extends from the outer electrode 19 to the inner electrode 20 of the capacitor 3.

The stripping element 21 may have a lamellar shape and extends parallel to the longitudinal axis L of the tubular flow chamber 9.

In the embodiment of FIG. 2, a further stripping element 22 is provided which is arranged symmetrically with respect to the longitudinal axis L of the device 1 and is thus likewise attached to the contact surface 5 of the outer electrode 19. In Fig. 2, the inner electrode 20 is fixed, whereas the outer electrode 19 is rotatable. The outer electrode 19 thus forms a rotatable shaft 23, as indicated by the arrow on the right side of Fig. 2. 2 corresponds to the cross section along the section line AA of the left part of FIG. 2. Since the stripping elements 21, 22 are rotationally rigidly connected to the rotatable shaft 23, the stripping elements 21, 22 consequently rotate with rotation of the shaft 23 and deposits along the contact surface 5 of the inner electrode 20. Deposits which have settled on this contact surface 5 are scraped off and removed by the stripping elements 21, 22, because the stripping elements 21, 22 relative to the contact surface 5 of the inner electrode 20 are designed to be movable. Another advantage of this embodiment is that by the movable scraper elements 21, 22 form a movable mixing tool, which mixes the medium in the treatment chamber 6. With a sufficient rotational speed, this mixing tool can achieve a turbulent mixing of the medium in the treatment space 6, so that the stripping element 21, 22 can form a turbulent mixer 16. A further embodiment of the device 1 according to the invention, in which the electrodes 5 are arranged collinear with one another, is shown in FIG.

The structure of the treatment chamber 2 as a tubular flow chamber 9 essentially corresponds to the structure of FIG. 2. The following will explain in more detail the differences between FIG. 3 and the embodiment of FIG. 2. The electrodes 10 in the embodiment of FIG. 3 are arranged colinearly. There are two ring-shaped or tubular outer electrodes 19, 19 'along the longitudinal axis L of the device 1 spaced from each other, with an intermediate, also tubular Iso- lator 24. The outer electrodes 19, 19' and the insulator 24 have all the same diameter. Instead of an inner electrode 20, an inner insulator 25 is provided in the embodiment of FIG. 3, which may be rod-shaped or tubular and coaxial with the unit of Au ßenelektroden 19, 19 'and insulator ring 24 is arranged.

In contrast to the embodiment of FIG. 2, the stripping elements 21, 22 in the embodiment of FIG. 3 are rotationally rigidly connected to the inner insulator 25, wherein the inner insulator 25 is designed as a rotatable shaft 23, so that the stripping elements 21, 22 together rotate with the inner insulator 25, as indicated by the arrows in the right side of Fig. 3. The outer electrodes 19, 19 'and the insulator 24 are fixed in the embodiment of FIG. 3, so that the stripping elements 21, 22 are moved relative to the contact surface 5 of the outer electrodes 10 or the insulator 24 and scrapings are scraped off at this contact surface 5 ,

4, a further embodiment of a device 1 according to the invention is shown schematically. The electrodes 10 of this embodiment are conically arranged.

As in the embodiment of FIG. 2, the embodiment of FIG. 4 also has an outer electrode 19 and an inner electrode 20. The outer electrode 19 is configured funnel-shaped as a hollow cone. The inner electrode 20 is cone-shaped, wherein the axes of rotation of the conical outer electrode 19 and the conical inner electrode 20 coincide and thus form a conical treatment chamber 6 of the treatment chamber 2 between them.

As indicated by the double-sided arrow on the left side of FIG. 4, the outer electrode 19 and the inner electrode 20 can be arranged to be displaceable relative to each other along the longitudinal axis L, thus providing a variable electrode spacing and a variable size of the treatment space 16 the embodiment of FIG. 3 can realize. In the embodiment of Fig. 4, as in the previous embodiments of Figs. 2 and 3, one of the electrodes, namely the outer electrode 19, fixed, whereas the other electrode, in Fig. 4, the inner electrode 20 is formed as a rotatable shaft 23 is.

The embodiment of FIG. 4 also has two stripping elements 21, 22, which are arranged on one of the electrodes 10. In the embodiment of FIG. 4, the stripping elements 21, 22 are fastened to the surface of the outer electrode 19 facing into the treatment space 4. Because the

Stripping elements 21, 22 are attached to the fixed outer electrode 19, they do not rotate in the embodiment of FIG. 4. The relative movement of the wiping elements 21, 22 to the contact surface 5 is achieved in that the inner electrode 20 is formed as a rotating shaft 23, which is guided with its pointing into the treatment chamber 4 contact surface 5 on the festste- henden scraper elements 21, 22 along , whereupon deposits on this contact surface 5 can be scraped off.

Finally, a further embodiment of the device 1 according to the invention, which is shown in FIG. 5, will be discussed. The electrodes 10 of FIG. 5 are arranged as an annular gap.

For this purpose, the embodiment of FIG. 5 has a first tubular electrode 26, which at the same time also delimits the treatment chamber 6 of the treatment chamber 2. The further electrode is a plate electrode 27 which is associated with an end face 28 of the tube electrode 26 and which is arranged substantially perpendicular to the longitudinal axis L of the tube electrode 26. The contact surface 5 of the plate electrode 27 pointing into the treatment space 6 does not directly adjoin the end face 28 of the tube electrode 26, so that an annular gap 29 is formed between the end face 28 and the contact surface 5 of the plate electrode 27 pointing into the treatment space 6. As indicated by the arrows in Fig. 5, the medium to be treated flows through the tube electrode 26, then bounces on the plate electrode 27, is deflected at the plate electrode 27 and discharged through the annular gap 29 as an outlet opening 8 of the treatment chamber 2.

In the embodiment of FIG. 5, scraping elements 21 are arranged in the annular gap 29 and extend from the end face 28 to the plate electrode 27. In the embodiment of FIG. 5 with annular gap 29, the stripping elements 21 are connected to one of the electrodes 26, 27. In addition, the electrodes 26, 27 designed to be movable relative to each other. This can be achieved, for example, in that one of the electrodes 26, 27 is stationary and the other electrode 26, 27 is designed as a rotatable shaft or plate. It is also possible to design both electrodes 26, 27, but in different directions of rotation about the longitudinal axis L rotatable.

In the embodiment of FIG. 5, the boundary surface of the tube electrode 26 pointing into the treatment space 6 is additionally provided with a surface coating 15, which on the contact surface 5 of the electrode 26, in addition to the stripping elements 21, 22, has a further free holder 4 formed.

reference numeral

1 device

2 treatment chamber

3 capacitor

4 free holders

5 contact area

6 treatment room

7 inlet opening

8 outlet opening

9 flow chamber

10 electrodes

11 power lines

12 voltage source

13 pulse generator

14 wall section

15 surface coating

16 turbulent mixers

17 turbulator

18 dimples

19, 19 'outer electrode

20 inner electrode

21 stripping element

22 Further stripping element

23 wave

24 insulator

25 inner insulator

26 Tubular electrode

27 plate electrode

28 face

29 annular gap

L longitudinal axis

Claims

claims

1. Device (1) for the treatment of media, in particular for the electroporation of foods, comprising:

a treatment chamber (2) for receiving the medium to be treated;

- At least two electrodes (10) for generating an electric field in the

treatment chamber

(2); and

at least one free holder (4) for protection against deposits of the medium on a contact surface (5) of the device (1) coming into contact with the medium. 2. Device (1) according to claim 1, characterized in that the at least two

Electrodes (10) are connected to a pulse generator (13).

3. Device (1) according to claim 2, characterized in that the electrodes (10) are arranged parallel, coaxial, collinear, conical or as an annular gap.

4. Device (1) according to claim 2 or 3, characterized in that at least one electrode (10) forms a wall portion (14) of the treatment chamber (2).

5. Device (1) according to one of claims 1 to 4, characterized in that the treatment chamber (2) has an inlet opening (7) and an outlet opening (8) spaced therefrom.

6. Device (1) according to one of claims 1 to 5, characterized in that a surface coating (15) on the contact surface (5) the free holder (4) is formed.

7. Device (1) according to one of claims 1 to 6, characterized in that the free holder (4) comprises a stripping element (21, 22) for scraping deposits on the contact surface (5).

8. Device (1) according to claim 7, characterized in that the stripping element (21, 22) is arranged on an electrode (10).

9. Device (1) according to claim 7 or 8, characterized in that the scraper element (21, 22) extends from one electrode (10) to another electrode (10).

10. Device (1) according to one of claims 7 to 9, characterized in that the stripping element (21, 22) is designed to be movable relative to the contact surface (5).

1 1. A device (1) according to claim 10, characterized in that the stripping element (21, 22) is rotationally rigidly connected to a rotatable shaft (23).

12. Device (1) according to claim 1 1, characterized in that one of the electrodes (10) forms the rotatable shaft (23).

13. Device (1) according to one of claims 1 to 12, further comprising a turbulent mixer (16) for generating a turbulent mixing of the medium in the treatment chamber (2).

14. Device (1) according to claim 13, characterized in that the turbulent mixer (16) has a static mixer, turbulators (17), a turbulence generator and / or movable components.

15. Device (1) according to claim 13 or 14, characterized in that the scraping felement (21, 22) forms the turbulent mixer (16).