Method for supercooling and freezing water-containing food products and biological objects

Abstract

FIELD: food freezing.SUBSTANCE: relates to freezing products and biological objects. The product to be supercooled and frozen is placed in a radio-transparent container of a device that includes two 2D-matrices of flat electrodes insulated from each other, located on the sides of the radio-transparent container. The phase-modulated signal generator is connected to the signal inputs of multi-channel controlled power amplifiers with built-in phase regulators, the control inputs of which are connected to the controller outputs. The outputs of the power amplifiers are connected to the flat electrodes of the matrices. The controllers generate control pulses according to a random law so that between the matrices, at least on two flat electrodes, there is always a generator voltage, which creates in the volume of the radio-transparent container an electric field with a frequency from 100 kHz to 1 MHz, phase-modulated from 0 to 180 degrees with a frequency from 1 to 500 kHz, chaotically changing its direction with a frequency from 2 to 100 kHz and a voltage from 10,000 to 100,000 V / m, depending on the distance between the electrodes of the matrices.EFFECT: preventing water crystallization when freezing products.1 cl, 3 dwg

Description

[0001] The invention relates to the field of freezing food products and biological objects, and is intended to prevent the crystallization of water in food products, and to prevent the formation of destructive ice crystals in the cells of biological objects and molecular chains of organic objects during the “water-ice” phase transition.

[0002] The difference in the densities of water and ice explains the destructive effects of crystallization on the internal structures of biological objects and products of organic and inorganic origin when their temperatures drop below the phase transition temperatures of free and bound water. Ice crystals formed inside cells and in suspension in the intercellular space create mechanical stress due to the increase in internal volume. The inevitable fusion of primary crystals and their subsequent growth (due to dehydration of tissues adjacent to the crystals) lead to the complete or partial mechanical destruction of cellular and intercellular structures. Simultaneously, the concentrations of dissolved substances increase, and the effect of these concentrations on the product during storage leads to protein denaturation, fat oxidation, destruction of carbohydrates and vitamins, and, consequently, to the degradation of the organoleptic properties of the original product.

[0003] It is necessary that the temperature decrease does not cause economic and biological changes in the product.

[0004] In physics, the term "cryoscopic temperature" is used to describe the temperature at which ice crystals begin to form in the liquid phase of food products and biological objects. This concept is used in refrigeration processing of foods to classify processing methods. For example, based on cryoscopic temperature, the following are distinguished:

[0005] • Cooling - processing at a temperature above cryoscopic, which preserves the appearance and condition of the product.

[0006] • Freezing is a treatment at temperatures below cryoscopic, which transfers the product to a state in which it can be stored for a long time.

[0007] • Supercooling and freezing - an intermediate position between cooling and freezing, when the temperature of the products is below the cryoscopic temperature, but not more than 1.5-2°C.

[0008] Supercooling allows food to be preserved in its original fresh state at temperatures below freezing without freezing. However, supercooling is unstable and can deteriorate at any time, leading to the formation of uneven and larger ice crystals, tissue damage, and loss of quality and nutrients. Although the effectiveness of supercooling preservation has been confirmed in laboratory and pilot tests, the stability of supercooled food remains an open question, limiting its application on an industrial scale.

[0009] Cryoscopic temperature values ​​vary for different types of products and depend on the concentration of soluble substances in the cell sap. For example:

[0010] •for meat from -0.6 to -1.2°C;

[0011] • for milk -0.55°C;

[0012] • for eggs -0.5°C.

[0013] A known method of vacuum freezing of fish, according to which a product 50 mm high is frozen in a vacuum freezer, after 60 minutes, when the temperature on the surface of the product reaches the cryoscopic -1.8 ° C, a vacuum pump is turned on, reducing the pressure in the chamber from atmospheric 101 kPa to 10 Pa at a speed of 15 m 3 / h, and an ultrasonic generator with a radiation frequency of 70 kHz, which is switched off after 25 minutes when the temperature in the product reaches -20°C, and freezing is carried out until the temperature in the product reaches -40°C for 30 minutes. The invention makes it possible to reduce the duration of product freezing, reduce deformation and destruction of the internal structure of the frozen fish. (Patent of the Russian Federation No. 2 815 955, IPC A23B 4 / 06, F25D 13 / 00, published March 25, 2024).

[0014] The disadvantage of this technical solution is some sublimation of the frozen product and significant crystallization of the remaining water in it, so that the quality of the product is not sufficiently preserved with this vacuum freezing method.

[0015] The closest to the proposed method is the method of freezing water-containing food products, according to which the rapid cooling of the food product begins with the simultaneous creation of a non-uniform alternating electric field around the food product being frozen, wherein the non-uniform alternating electric field is created using matrices of electrodes, and the control of the directions, speed and nature of the movements of the static gradients of the electric field strength at each point of the field is carried out by organizing reciprocating cycles of movement of areas of the static gradient of the electric field strength along the horizontal plane of the cooled object, during the entire period of the water-ice phase transition by turning on the electrode potentials on the matrices of the field modulator, control of the directions,the speed and nature of the movements of the static gradients of the electric field intensity organizes the cyclic movement of water dipoles along closed trajectories with the formation of glassy ice that does not contain crystals, while the effect of a non-uniform alternating electric field is carried out until the completion of the water-ice phase transition, determined by a decrease in the electrical conductivity of the food product, and rapid cooling is continued until the food product reaches a storage temperature set in the range from -15 to -20 ° C, while the distance between the matrices of the field modulator is from 50 to 150 mm, the pitch of the electrodes in the matrices of the field modulator is 10 mm, and the cyclic frequency of movement of the areas of the static gradient of the electric field intensity is from 20 to 100 Hz. (Patent of the Russian Federation No. 2 778 148 IPC A23L 3 / 36, F25D 13 / 00, published 15.08.2022).,

[0016] This method of freezing water-containing food products eliminates the deterioration in product quality due to sublimation. However, this method involves a crystallization platform, making it ineffective in maintaining a crystal-free ice structure (as evident from the temperature change graph). The technical challenge addressed by this proposal is to improve product quality through the efficiency of supercooling and freezing.

[0017] To solve this technical problem, a method is proposed for supercooling and freezing water-containing products and biological objects, characterized in that the product to be supercooled and frozen is placed in a radio-transparent container of a device that includes two two-dimensional matrices of flat electrodes isolated from each other, placed on the sides of the radio-transparent container, a phase-modulated signal generator connected to the signal inputs of multichannel controlled power amplifiers with built-in phase regulators, the control inputs of which are connected to the outputs of the controllers, the outputs of the power amplifiers are connected to the flat electrodes of the matrices, wherein the controllers form control pulses according to a random law so that between the matrices there is always, at least on two flat electrodes, a generator voltage that creates an electric field with a frequency of 100 kHz to 1 MHz in the volume of the radio-transparent container,phase-modulated from 0 to 180 degrees with a frequency from 1 kHz to 500 kHz, chaotically changing its direction with a frequency from 2 kHz to 100 kHz and a voltage from 10,000 to 100,000 V / m, depending on the distance between the electrodes of the matrices.

[0018] The applicant did not find any other technical solutions with a similar purpose and a similar set of essential features during a search of scientific and technical literature and patent documentation. The proposed technical solution does not clearly follow from the prior art. Devices operating according to the proposed method for supercooling and freezing water-containing food products and biological objects can be manufactured using existing equipment and known materials. The industrial applicability of the proposed method is beyond doubt. The applicant has manufactured and successfully tested laboratory prototypes of devices for supercooling and freezing water-containing food products and biological objects. Therefore, the applicant believes that the proposal in this application meets the invention eligibility criteria of "novelty," "inventive step," and "industrial applicability."

[0019] To implement the proposed method for supercooling and freezing water-containing food products and biological objects, a device may be used comprising a radio-transparent container, a container cooling element, at least two two-dimensional matrices of flat electrodes insulated from each other, located on the sides of the radio-transparent container, and a phase-modulated signal generator connected to the signal inputs of multichannel controllable power amplifiers corresponding to the number of matrices, the control inputs of which are connected to the outputs of the controllers, the outputs of the power amplifiers being connected respectively to the flat electrodes of the matrices. The controllers may be implemented, in particular, as random number generators, the inputs of the controllers being connected to the control unit of the device.

[0020] The essence of the proposal is explained by the drawings. Fig. 1 shows a functional diagram of the device, Fig. 2 shows graphs comparing freezing rates, and Fig. 3 shows graphs comparing supercooling rates with and without the use of the proposed method.

[0021] Figure 1 shows: a radio-transparent container 1 for accommodating the object of supercooling / freezing, a controlled generator 2 of alternating electric voltage, multi-channel controlled power amplifiers 3, 4 with a built-in phase regulator, an element 5 of the matrix for creating an alternating electric field, controllers 6, 7 of the multi-channel power amplifier, a programmable unit 8 of the device control. The cooling element of the container is not shown.

[0022] The device operates as follows: the product to be cooled is placed in a radio-transparent container 1, and the cooling element (cold air flow) is simultaneously activated. Controllers 6 and 7 generate control pulses such that the voltage of generator 2 is always present on at least two flat elements 5 of the two matrices. An electric field with a strength of 10,000 to 100,000 V / m is created between these elements 5, depending on the relative distance between these elements. If, for example, controllers 6 and 7 generate control pulses at their outputs according to a random law, the electric field gradient within radio-transparent container 1 will chaotically change its magnitude and direction.

[0023] The feasibility of the invention was tested in a series of experiments involving supercooling and accelerated heat removal of the following biological and organic objects: water, vegetables (tomato). The following embodiments of the invention are specific examples of the claimed invention and do not limit the scope of the claims.

[0024] A series of experiments with water were conducted under the following conditions: samples were supercooled in 12 ml plastic test tubes with a diameter of 15 mm, containing 10 ml of water. Cooling was accomplished by blowing cold air with an average chamber temperature of -9.5 degrees Celsius. The field strength was 63,000 V / m, the generator carrier frequency was 330 kHz, the modulation was 37 kHz, and the gradient displacement was 2.4 kHz. The number of elements in each matrix was 18 (two-dimensional field of 3x6 elements).

[0025] One test tube containing water was designated as a control and subjected to conventional supercooling. The second test tube containing water was supercooled using the method proposed in this invention.

[0026] The moment of end of exposure of the object to the electric field was determined by measuring the temperature of the object.

[0027] The experimental results indicate that the orientation along the lines of force and the synchronous movement of dipole molecules along closed trajectories impart viscosity to water and prevent the molecules from tending to occupy an energetically favorable position in a node of the hexagonal lattice of ice when the temperature drops below the cryoscopic temperature.

[0028] When the heat removal process is accompanied by a controlled electric field, the water in biological objects is supercooled without the formation of a crystalline lattice. In fact, the water remains liquid under the influence of the electric field when the temperature drops from -2°C to -8°C.

[0029] The graphs clearly show that under the influence of the electric field, the temperature of the cooled water decreases, passing 0°C, and then continues to decrease at the same rate to -8°C. Meanwhile, the water in the test tube, which was outside the field, also passed the cryoscopic point under this supercooling method. However, due to the instability of this state, as described above, crystallization began, releasing a large amount of energy, leading to the temperature reaching the crystallization plateau (a temperature close to 0 degrees Celsius). After crystallization was complete, the temperature of the water in the unexposed test tube equaled that of the water under the field.

[0030] After synchronizing and stabilizing the temperatures in both test tubes, a timed hold was performed to confirm that the water in the test tube remained stable and liquid at a temperature significantly below the cryoscopic temperature. Next, the temperature in the cooling chamber was raised to +20 degrees Celsius. As the temperature in the chamber increased, the temperature of the water in the exposed test tube began to gradually rise and reached the temperature in the chamber containing the test tube, which was outside the exposure zone. The temperature then increased to the cryoscopic temperature and reached the defrosting plateau.

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