EP1113728A1

EP1113728A1 - Apparatus and process for preserving foods

Info

Publication number: EP1113728A1
Application number: EP99946161A
Authority: EP
Inventors: Hubertus Lelieveld
Original assignee: Unilever PLC; Unilever NV
Current assignee: Unilever PLC; Unilever NV
Priority date: 1998-09-14
Filing date: 1999-09-10
Publication date: 2001-07-11
Also published as: AU5862399A; WO2000015054A1

Abstract

An apparatus (1) for preserving foods (2) comprises magnets (3, 7) for generating a magnetic field. According to the invention, such an apparatus comprises concentrating means (4) for locally concentrating the generated magnetic field in at least two concentration regions (5) and conveying means (6) for conveying the foods (2) through the concentration regions (5). This enables easy conveyance of the foods through a magnetic field of varying intensity and a good preservation, while the field generated by the magnets (7) and/or coils (8) may be static.

Description

Apparatus and process for preserving foods .

The invention relates to an apparatus for preserving foods, comprising generating means for generating a magnetic field. Such an apparatus is known from U.S. Patent 4,424, 079.

In the known apparatus, the generating means are formed by a coil m which an oscillating magnetic field is generated which has a preservative effect on foods. The magnetic field has a frequency between 5 and 500 kHz and an intensity between 2 and 100 T. The generation of such an oscillating magnetic field requires a high-frequency alternating current of high amplitude, which must be generated by means of a suitably dimensioned oscillator- mtensifier combination. Such an mtensifier is relatively expensive and has a high energy consumption. Moreover, the above frequencies and field intensities generate vigorous vibrations m the apparatus. To enable resistance to these vibrations, this known apparatus must be of mechanically very strong construction.

EP 434558 and US 4,065,386 disclose use of series or stacks of annular magnets for preventing or inhibiting growth of bacteria, algea, or protista m a fluid medium. Magnetic field strengths are up to 0.4 T (4000 gauss) .

Draw back of the use of such annular magnets is that there are limitations to the field strength used. For e.g. field strengths of larger than 10 T, mechanical forces are too big, and collapse of the equipment will occur. Additionally, as such field strengths cannot m reality be obtained using permanent magnets, electromagnets will have to be used. In the set up of stacks of annular magnets there will be little room for coils, to induce the magnetic field, and if there would be then there may be problems m dissipating heat. Hence, using stacks of annular magnets for purposes as herein disclosed poses technical limitations . It is an object of the invention to remove the above and other drawbacks of the prior art and to provide an apparatus of the type mentioned m the opening paragraph hereof, which readily makes it possible to subject foods to a magnetic field of varying intensity. It is a further object of the invention to provide an apparatus of the type mentioned in the opening paragraph hereof, which is relatively simple and inexpensive. It is a particular object of the invention to indicate such an apparatus for which no power alternating voltage amplifier is required and m which no strong vibrations are generated.

It is also an object of the invention to indicate a process for preserving foods with relatively simple technical means. It is yet a further object of the invention to be able to provide the above m high magnetic field strengths.

To this end, an apparatus of the type mentioned m the opening paragraph is characterized according to the invention by concentrating means for locally concentrating the generated magnetic field m at least two concentration regions, and conveying means for conveying the foods through the concentration regions. This can suitably be achieved by an apparatus (1) for preserving foods (2), comprising generating means (3) for generating a magnetic field, characterized by concentrating means (4) for locally concentrating the generated magnetic field m at least two concentration regions (5) and conveying means (6) for conveying the foods (2) through the concentration regions (5) , wherein the generating means (3) comprises a permanently magnetic body (7) or a magnetizable body (7), wherein said body (7) is not a closed, annular body. What is accomplished by locally concentrating the magnetic field m concentration regions and conveying the articles (foods etc.) through the concentration regions is that the articles to be treated are exposed m a simple manner to a magnetic field of varying intensity. The magnetic field generated by the generating means may then, in principle, be a static field, so that no oscillating magnetic field is required.

According to the invention, therefore, the "oscillation" of the field, i.e. the intensity varying with time, is obtained by the movement of the articles to be preserved through a magnetic field with an intensity varying with place.

Preferably, the generating means comprise at least one coil and one magnetizable body. The magnetizable body, which is made of, e.g., metal (iron) or a suitable ceramic type, guides the magnetic field generated by the coil and may also serve as concentrating means. It is possible, however, to design the apparatus such that the generating means comprise a permanently magnetic body. In that case, the coils may be omitted, if necessary, although it is possible to use a permanently magnetic body, optionally m combination with a coil.

The apparatus according to the invention is advantageously of such design that the concentrating means are formed by protruding elements of the body. Thus, a suitable local concentration of the generated magnetic field can be readily achieved with concentrating means which are integral with the (magnetizable or permanently magnetic) body. This can suitably be achieved by an apparatus (1) for preserving foods (2) , comprising generating means (3) for generating a magnetic field, characterized by concentrating means (4) for locally concentrating the generated magnetic field in at least two concentration regions (5) and conveying means (6) for conveying the foods (2) through the concentration regions (5), wherein the concentrating means (4) are formed by protruding elements, and wherein at least 4 protruding elements (4) in total are present. Preferably, the protruding elements (4) are an integral part with the body (7) .

The conveying means may comprise a conveyor belt which passes the foods through the concentration regions at a constant speed. The conveying means may also be arranged to supply the articles such that they fall, while being decelerated or not, through the concentration regions at a constant speed (decelerated) or constantly increasing speed (not decelerated) . Most preferred will be conveying means in the form of a tube or pipe containing a pu pable food product, such as plastic or fluid food product. Examples of such products are sauce, soup, juice, jam, dressings, mayonnaises, spreads, ice cream, tea, milk, coffee etcetera. The invention further provides a process for preserving foods, comprising the generation of a magnetic field, which process is characterized, according to the invention, by locally concentrating the generated magnetic field in at least two concentration regions and conveying the foods through the concentration regions.

The invention will be explained below with reference to the drawings . Fig. 1 diagrammatically shows, in top plan view, a first embodiment of an apparatus according to the invention;

Fig. 2 diagrammatically shows, in top plan view, a second embodiment of an apparatus according to the invention;

Fig. 3 diagrammatically shows, in side view, the apparatus of Fig. 2; and

Fig. 4 diagrammatically shows, in more detail, the principle of the invention.

The embodiment of an apparatus 1 for preserving foods 2, which embodiment is diagrammatically shown in Fig. 1 and only by way of example, comprises generating means 3 for generating a magnetic field. In the case shown, the generating means 3 are formed by the body (yoke) 7 of a substantially U-shaped permanent magnet. The body 7 is provided with pairs of protruding elements 4 (e.g. "teeth"- like) , which form concentrating means for locally concentrating the generated magnetic field. In the example shown, seven pairs of protruding elements 4 are present, each pair of opposite protruding elements forming a concentration region 5, as will be explained hereinafter with reference to Fig. 4. It will be clear that other numbers of pairs of protruding elements are also possible, e.g. five, ten, fifty or even hundred pairs of protruding elements.

Furthermore, in the example shown, the concentration regions (5 in Fig. 4) are in alignment, in accordance with the linear conveyance of the articles (foods) 6. It will be clear that a, for instance, arcuate arrangement of the concentration regions, preferably in combination with an arcuate conveyance of the foods 2, is also possible. In the example of Fig. 1, the conveying means 6 for conveying the foods 2 through the concentration regions 5 are formed by a conveyor belt. Alternatively, other conveying means 6, such as a roller path or a train of containers, may be used as well. Most preferred will be conveying means in the form of a tube or pipe containing a pumpable food product, such as plastic or fluid food product. Examples of such products are sauce, soup, juice, jam, dressings, mayonnaises, spreads, ice cream, tea, milk, coffee etcetera.

The protruding elements 4 may be formed by providing in the body 7 such recesses as to yield the protruding elements. The forming of the protruding elements (concentrating means) 4 and the body 7 in one piece has the advantage of yielding a simpler construction and a better magnetic guidance.

It will be clear that, in practice, the apparatus 1 may comprise additional parts, which, however, are not shown in the figures, for clarity's sake. In the embodiment of Fig. 2, additional protruding elements 4' of an additional body 7' are disposed transversely (or at any other angle) to the protruding elements 4 of the body 7, in a manner such that the additional protruding elements 4 ' are at right angles to the protruding elements 4 (i.e. perpendicular to the plane of the drawing) . Moreover, the additional protruding elements ' are always staggered with respect to the protruding elements 4. What is thus accomplished is that the concentration regions (5 in Fig. 4), which are successively traversed by an article 2, is formed by the protruding elements of alternately one and the other magnet configuration (bodies 7, 7' and coils 8, 8'). Moreover, the successive concentration regions are always perpendicular to each other here, which has an additional preservative effect due to the alternating orientation of the magnetic field. The apparatus 1 of Fig. 2 is shown in Fig. 3 in side view. The generating means 3 comprise, as shown, two magnet configurations each having a body (yoke) 7, 7' and a coil 8, 8' disposed round the respective body. The concentrating means are formed by the ends (protruding elements 4, 4' in Fig. 2) of the bodies 7 and 7'. These ends enclose a concentration space 9 through which the articles (2 in Fig. 2) are conveyed.

As shown in Fig. 4 in more detail, the concentrating means (pairs of protruding elements 4), in each case, form a concentration region 5 of relatively high magnetic field intensity, while between the concentration regions 5 the magnetic field intensity is relatively low. As a result, a passing article is subjected to a varying field intensity, the effect of which corresponds to an oscillating magnetic field. The frequency of the apparent oscillations is determined by the conveying speed of the articles (or other form of food, e.g. liquid) and the mutual distances of the concentration regions.

In the above examples, the concentrating means are formed by protruding elements of a body (yoke) , with one or more coils disposed round the body. It is also possible, however, to form local concentration regions with a series of coils (e.g. arranged in parallel), which may or may not each be provided with a yoke, so that the concentrating means and the generating means may essentially coincide.

The concentration regions are preferably in a straight line to enable easy conveyance of the foods through these regions. It is also possible, however, to arrange the concentration regions in another configuration, e.g. in a circular arc. It is further possible that an article to be treated (foods etc.) does not traverse all the concentration regions.

To enable the generation of high magnetic field intensities with relatively low losses, it is advantageous to use superconductive magnet coils. To this end, the apparatus should be provided with cooling means for cooling the magnets. In that case, the magnet coils are preferably made of a material which is permanently superconductive at a highest possible temperature. Preferably, the coils are alternately energized.

The foods may be conveyed through the apparatus according to the invention both in packed and in unpacked condition. The foods may also be conveyed manually.

It is also possible to design the apparatus such that the articles to be treated traverse the magnetic concentration regions while falling. By the articles falling, a relatively high conveying speed of the articles through the concentration regions can be readily obtained. In this case, the conveying means are for supplying and discharging the articles and, consequently, only indirectly for the conveyance through the magnetic regions. The falling may be decelerated (e.g. along an inclined surface, i.e. essentially sliding or rolling) or not be decelerated (in the free space).

It will be clear to skilled persons that the invention is not limited to the embodiments shown and that many modifications and additions are possible without departing from the scope of the invention. The invention further encompasses a process for preserving foods (2), comprising the generation of a magnetic field, characterized by locally concentrating the generated magnetic field in at least two concentration regions (5) and conveying the foods (2) through the concentration regions (5) . Preferably, such process is effected by usage of an apparatus as described herein.

It may be preferred for some purpose to combine such preservation method as herein described with alternative preservation methods. This can be effected in a process as above, wherein the foods are, prior to, simultaneously, of after subjecting it to the magnetic field is also subjected to alternative treatments, selected from the group chosen of electric field, pulsed electric fields, ultra high pressure, pulsed ultra high pressure, radiation by alpha, beta or gamma rays, heat, visible light, non-visible light, and combinations thereof. Likewise, it may be possible to subject to food to multiple treatments (or series) of a varying magnetic field such as herein described, e.g. by operating two or more equipment, with a given time in between. Alternatively, the food may be passed more than once through the same equipment, with given time in between.

The invention further encompasses foodstuffs, preserved according to the invention as disclosed herein.

Claims

1. An apparatus (1) for preserving foods (2), comprising generating means (3) for generating a magnetic field, characterized by concentrating means (4) for locally concentrating the generated magnetic field in at least two concentration regions (5) and conveying means (6) for conveying the foods (2) through the concentration regions (5), wherein the generating means (3) comprises a permanently magnetic body (7) or a magnetizable body (7), wherein said body (7) is not a closed, annular body.

2. Apparatus (1) for preserving foods (2), comprising generating means (3) for generating a magnetic field, characterized by concentrating means (4) for locally concentrating the generated magnetic field in at least two concentration regions (5) and conveying means (6) for conveying the foods (2) through the concentration regions (5), wherein the concentrating means (4) are formed by protruding elements, and wherein at least 4 protruding elements (4) in total are present.

3. An apparatus according to claim 2, characterized in that the protruding elements (4) are integral with the body

(7) .

4. An apparatus according to claim 1-3, characterized in that the generating means (3) comprise at least one coil

(8) and one magnetizable body (7).

5. An apparatus according to claim 1-4, characterized in that the generating means (3) comprise a permanently magnetic body (7) .

6. An apparatus according to any one of claims 1-5, characterized in that the generating means (3) comprise at least two bodies (7, 7') with concentrating means (4) arranged at an angle to each other.

7. An apparatus according to claim 6, characterized in that the protruding elements (4, 4') of the bodies (7, 7') are staggered with respect to each other such that, in operation, the respective protruding elements (4, 4') form alternately successive concentration regions (5) .

8. An apparatus according to claim 4-7, characterized in that the coils are alternately energized.

9. An apparatus according to any one of the preceding claims, characterized in that the conveying means (6) comprise a conveyor belt.

10. An apparatus according to any of the preceding claims, characterized in that the conveying means (6) comprise a tube or pipe, containing a pumpable food or drink product, such as plastic or fluid food product.

11. A process for preserving foods (2), comprising the generation of a magnetic field, characterized by locally concentrating the generated magnetic field in at least two concentration regions (5) and conveying the foods (2) through the concentration regions (5) .

12. Process for preserving foods (2), characterized in that preservation is effected by usage of an apparatus according to claim 1-10.

13. Process according to claim 11 or 12, wherein the foods (2) are, prior to, simultaneously, of after subjecting it to the magnetic field is also subjected to alternative treatments, selected from the group chosen of electric field, pulsed electric fields, ultra high pressure, pulsed ultra high pressure, radiation by alpha, beta or gamma rays, heat, visible light, non-visible light, and combinations thereof.

14. Foods, preserved according to the process of claim 11- 13.