CZ2019366A3 - Device and method for preparing food by a pulsed electric field - Google Patents

Abstract

The present solution provides a food treatment device comprising an AC power supply and at least two contact electrodes (8, 9), each contact electrode being divided into several segments (11), and the device further comprising a control unit (6) controlling the AC power supply. and controlling the supply of current to the electrode segments. In a specific embodiment, a device is described comprising an isolating transformer (1), a rectifier module (2), a capacitor bank (3), a current probe (4), an AC generator (5), a control unit (6), a field relay (7) and contact (pulsation) electrodes (8, 9) divided into segments (11). The present solution further provides a method of food preparation using said device.

Description

Apparatus and method for food preparation by pulsed electric field

Field of technology

The invention relates to a device for the home preparation of foodstuffs, in particular fruit and vegetables, for direct consumption or culinary processing. The device works on the principle of using a pulsed electric field to damage some cell membranes, and thus to release most of the cellular fluids, thereby changing the texture and digestibility of food without losing biologically active substances.

Prior art

One of the possibilities of food preparation is the use of pulsed electric heating at lower temperatures (temperatures are below 42 ° C, so such food preparation is also suitable for lovers of the so-called raw diet). In this way, the effectiveness of all healthy substances can be maintained. In addition, the energy intensity of the whole food processing process may be lower than with conventional processing.

The principle of pulsed electric heating or processing is known, and at the same time it is the subject of very intensive basic and applied research. In the last few years, it has found application in the food processing industry. The pulsed electric field can be used, for example, to deactivate biological contamination of fluids, as proposed, for example, in U.S. Pat. No. 6,746,613 B2. A similar use of a pulsed electric field is also described in EP 2543254 A1 by Nestlé, which uses it to inactivate bioactive components in milk during pasteurization in order to preserve it.

However, systems are also known for applying a pulsed electric field to more or less solid food products, such as meat or vegetables, including potatoes. An example is WO 2011/139144 A1, which describes a method and system for such processing.

Currently, around 10 companies worldwide manufacture equipment enabling electrical pulse applications in the food industry. However, culinary and kitchen applications in general are still unique and non-consumable. The Dutch company IXL Netherlands B.V. The Netherlands (www.innovation-xl.com), whose low-voltage products, however, lack the ability to directly damage cell membranes. This principle is protected, for example, by U.S. Pat. No. 9565869 B2.

High-voltage applications face performance and safety limitations in households that prevent their wider deployment to small consumers.

Thus, there is still a need to develop a solution that can be used in a normal kitchen operation.

The essence of the invention

The present invention solves this object by providing a food treatment device comprising an AC voltage source and at least two contact electrodes, each contact electrode being divided into several segments, and the device further comprising a control unit controlling the AC voltage source and controlling the voltage supply to the electrode segments.

The main benefit of this device is the division of contact electrodes into several segments. This makes it possible to distribute the required power input more evenly over time, and in addition to automatically regulate the efficiency of the pulse process in smaller volumes of processed material. Processed food can be thanks to

-1 CZ 2019 - 366 A3 subject the segmentation of the electrodes to the action of a pulsed electric field gradually, whereby a sufficient processing of the food can be achieved with a substantially lower amount of electric current used.

The electrical conductivity G (S) of the material (foodstuff) is calculated according to the formula:

S c = y. _? where Tjc conductivity (Sm ¹ ), S is the cross-sectional area of the material (m ² ) and / is its length (m).

The passing electric current I (A) can then be calculated according to the formula:

I = U * G where U is the electrical voltage (V) and G is the electrical conductivity (S).

After installation, the relationship applies:

WITH

Because in this relation the area S is in the numerator of the fraction, the current flowing is directly proportional to this area. If this area is reduced n-fold (for example by dividing the electrode into n segments), the current required to achieve the effect of destroying the cell membrane in the food (as pulsed material) is also n-fold smaller. Because the pulse time is very short (in the order of milliseconds), pulsation by individual electrode segments can be advantageously used. The pulsation time of the material inserted between the electrodes with n segments is very short even in the case of pulsation after an individual segment, but the required value of the electric current required for the pulsation is n times smaller.

In a preferred embodiment, the segments of the at least one contact electrode are resiliently mounted, which facilitates contact with the food to be treated and increases the contact area with the food to be treated. More preferably, the ground contact electrode segments are resiliently mounted.

Another major benefit of the device is the use of an AC power source. Previously known devices for the treatment of food by pulsed electric field use direct current. The use of alternating current leads to polarization in the material, and thus to the contamination of the electrodes to a much lesser extent, compared to the use of direct current.

Preferably, the device further comprises a current probe formed, for example, by a low impedance resistor, on which the voltage drop is measured. From this information, the value of the electric current during pulsation can be derived. The current probe allows the control unit to automatically regulate the pulsation efficiency and terminate the pulsation based on exceeding a predetermined current flow limit (meaning complete or desired disruption of cell membranes in the food) or no further increasing current flow rate (indicating complete cell membrane disruption). ).

The AC voltage source may include an isolating transformer, a rectifier module connected thereto, and a capacitor bank connected thereto, connected to the AC voltage generator. The AC generator and capacitor bank can be connected via a current probe. In this case, the device is supplied from the mains by means of an isolating transformer, which reduces the supply voltage and further protects the mains supply from interference. In the rectifier module, the supply voltage is then rectified so that it can be used to charge the capacitor bank. The capacitor bank consists of several capacitors connected in parallel. They collect an electric charge, which is then used for pulsing.

- 2 CZ 2019 - 366 A3

The AC voltage generator can be formed by an h-bridge, which switches plus and minus very quickly (eg with a frequency of 10 kHz). At the beginning, the h-bridge is closed and there is therefore zero voltage in the connected circuit. The control module sends a signal whose length corresponds to the length of the pulse, after which the h-bridge starts transmitting alternating (pulsating) voltage for the time of receiving the signal. The H-bridge is fully controlled by the control unit.

The control unit can be formed by a programmable microcontroller, which receives an analog signal from the current probe and controls the AC voltage generator, i.e. the beginning and end of each pulse. Furthermore, the control unit controls the supply of voltage to the electrode segments. For this purpose, the device may comprise a field relay in which the control unit switches the relay, thereby determining the segment of the contact electrode to which the pulse will be sent. The field relay consists of a number of relays corresponding to the number of segments into which the pulsation electrodes are divided. By switching a certain relay, the segment of the pulsation electrode to which the voltage will be applied is determined.

The control unit can also advantageously be adapted to automatically control the end of the pulsation in the individual segments. At the first pulse in each of the segments, the value of the current flowing is written to the memory of the control unit. In the following pulses, the increase of the value of the flowing current is monitored. If it rises above a defined limit in one of the segments, the pulsation in that segment is terminated because the cell membranes in the food processed in that segment are already defined in a defined manner. The pulsation is also terminated when the current flow through the segment no longer increases for a period of time.

Thus, in some embodiments, the device of the present invention includes an isolating transformer, a rectifier module, a capacitor bank, a current probe, an AC generator, a control unit, a field relay, and contact (pulsation) electrodes divided into several segments.

The invention further relates to a method for treating foodstuffs, in particular fruit and vegetables, in which the foodstuff being treated is inserted between contact electrodes and then alternating voltage pulses are applied from the AC voltage source to the individual electrode segments. food. Preferably, the pulse voltage is always applied to one segment of the contact electrodes.

By food preparation is meant here the disruption of the cell membranes in the food, leading to a change in the texture of the food and to an increase in its digestibility, without heat heating.

Explanation of drawings

The invention is further illustrated by Fig. 1, which is a block diagram of an arrangement of a kitchen pulse electric processor with split selective automatic process control, and Fig. 2, which is a graph showing the effect of carrot pulsation (i.e., disruption of cell membranes in carrots) on squeezable juice compared to carrots not subjected to pulsation.

Examples of embodiments of the invention

Example 1: Equipment design

The device according to this example is shown in Figure 1. The food to be treated 10 is inserted between the working contact (pulsation) electrode 8 and the ground contact (pulsation) electrode 9, which are divided into the same number of segments 11. The food 10 is inserted between the electrode segments 11. so that the segments 11 touch them over as large an area as possible. This is ensured by the individual springing of the segments 11 of the grounding contact electrode 9 and by pressing the two electrodes 8 and 9 together.

-3GB 2019 - 366 A3

The supply voltage of the kitchen pulse electric processor is from a common electrical network. This voltage is first reduced in the isolating transformer 1, while the isolating transformer 1 also protects the electrical network from interference caused by the device. The voltage coming from the isolating transformer 1 is then rectified by the rectifying module 2 so that it can be used to charge the battery 3 of capacitors. Between the battery 3 of capacitors and the generator 5 of alternating voltage, a current probe 4 is placed, by means of which the magnitude of the passing current is measured. The AC voltage generator 5 converts the DC electrical voltage from the battery 3 of the capacitors back to the AC voltage, which is then used for its own pulsation. The control unit 6 controls the AC voltage generator 5. Based on the programmed algorithm and the reception of the signal from the current probe 4, the control unit 6 determines the start and end of the pulsation, and further controls the +/- switching and switches the current via the field relay 7 to the individual segments 11 of the working contact electrode 8.

Example 2: Food processing (carrots)

To illustrate the improvement in food digestibility, better extraction of juice from pulsated carrots compared to non-pulsated carrots in Figure 2 can be demonstrated.

Cylindrical carrot samples with a diameter of 5.8 mm and a height of 5 mm were prepared. These samples were inserted between the electrodes and treated with an electric pulse with a maximum alternating voltage of 200 V (corresponding to an electric field strength of 400 V / cm), a frequency of 20 kHz and a length of 10 ms. The samples thus treated were removed and subjected to a juice extraction test.

It can be seen from Figure 2 that the weight of the pulsed sample (with disrupted cell membranes) is reduced to less than 30% in 18 minutes of extraction, which means that 70% of the total weight has been extracted from it as juice. If the juice is extracted from a non-pulsed sample under the same conditions, only about 15% by weight of the juice is obtained in the same time. The juice, which contains healthy substances (especially vitamins), is thus better usable by the body from a pulsed sample than from a non-pulsed sample.

Industrial applicability

The invention can be used for culinary preparation of fruits and vegetables. Foods prepared in this way are characterized by the fact that all healthy substances are preserved, especially vitamins. In addition, due to the disruption of cell membranes, they are better absorbed in the human body. The invention can be used in practically every kitchen, both in the home and, for example, in restaurants.

Claims (9)

PATENT CLAIMS A pulse electric field food treatment device, comprising a control unit, a pulsed electric voltage source and at least two contact electrodes, characterized in that the pulsed electric voltage source is an alternating voltage source; in that each contact electrode (8, 9) is divided into several segments (11); in that the control unit (6) is adapted to control the AC voltage source and to control the supply of voltage to the electrode segments (11). Device according to Claim 1, characterized in that the segments (11) of the at least one contact electrode are resiliently mounted. Device according to claim 1 or 2, characterized in that it further comprises a current probe (4). Device according to any one of the preceding claims, characterized in that the AC voltage source comprises an isolating transformer (1), a rectifier module (2) connected thereto, a capacitor battery (3) connected thereto, connected to the AC voltage generator (5), the AC voltage generator (5) and the capacitor bank (3) are preferably connected via a current probe (4). Device according to any one of the preceding claims, characterized in that it comprises a device for switching the supply of voltage to the individual electrode segments (11), preferably a field relay (7). A method of treating food with a pulsed electric field using an apparatus according to any one of the preceding claims, characterized in that the food to be treated (10) is inserted between contact electrodes (8, 9) divided into segments (11) and subsequently the voltage applies an alternating pulse voltage to the individual electrode segments (11), which generates an electric field of a pulsed nature passing through the food (10) and disrupts the cell membranes in the food (10). Method according to Claim 6, characterized in that the pulsed alternating voltage is applied in each case to one segment (11) of the contact electrodes. Method according to Claim 6 or 7, characterized in that the pulsation is automatically regulated and / or automatically terminated separately on each electrode segment (11) (8, 9) on the basis of exceeding a predetermined current flow limit measured by the current probe (4). ) or on the basis of a no longer increasing magnitude of the flowing current measured by the current probe (4). Method according to claim 8, characterized in that the value of the current flowing through the electrode segment (11) is recorded during the first pulse, and that during further pulsing the increase of the value of the current flowing measured on each electrode segment (11) by the current probe (4) is monitored. , wherein if the values of the flowing current rise to a predefined limit or the current flow does not increase for a predetermined time, the pulsation on the given electrode segment (11) stops.