CN115005260A - Frozen meat thawing device based on flexible electrode - Google Patents

Abstract

The invention provides a frozen meat thawing device based on a flexible electrode, which comprises: the thawing pool can be used for containing thawing solution; the two parallel guide rails are positioned on two sides of the thawing pool and longitudinally extend in the horizontal direction; two paired electrode plate assemblies each configured to be vertically and slidably spanned between two guide rails by its electrode backing plate for ohmic heating of the frozen meat between the two electrode plate assemblies; and the U-shaped net rack is configured to be transversely erected on the two guide rails through two net rack hanging rods which are arranged between the two guide rails in a sliding mode, and is positioned between the two flexible electrode plate assemblies, so that the frozen meat for ohmic heating is accommodated, wherein the electrode plate assemblies comprise flexible electrodes attached to electrode lining plates, and the flexible electrodes are basically attached to the frozen meat accommodated in the U-shaped net rack during ohmic heating. The device of the present invention is advantageous for rapidly and uniformly thawing frozen meat.

Description

Frozen meat thawing device based on flexible electrode

Technical Field

The invention belongs to the technical field of meat product processing, and particularly relates to a frozen meat quick thawing device and application thereof.

Background

Cryopreservation is the most common preservation method used by the meat industry and is currently the predominant form of cold chain logistics for meat products both domestic and foreign, and thus the demand for frozen meat thawing technology is widespread and rapidly growing. Ideal frozen meat thawing techniques not only expect a rapid and efficient thawing process, but also require that the negative effects of juice loss, lipid oxidation, nutrient loss, and microbial contamination be minimized. However, in the current commercial processing or household processing occasions, the traditional natural (air) thawing or static (flowing) water thawing mode still stays in the mainstream, which not only can not meet the timeliness requirement, but also brings a series of quality and safety quality problems. The ultrasonic thawing and microwave thawing methods can greatly shorten the thawing time, but have the problems of meat quality damage and nutrient loss which are difficult to overcome. Generally, current frozen meat rapid-thawing equipment and nutrient loss technology have not yet obtained satisfactory commercial and domestic technical solutions, but have extensive and urgent market demands. Therefore, the development of related technical research and product development is expected to open up a new form or a new mode of commercial or household meat product processing equipment and create considerable social and economic benefits.

For the rapid thawing of frozen meat, two main technical ideas exist at present, one is from the utilization angle of the physicochemical properties of the frozen meat and a heat transfer medium, and the rapid thawing is attempted by improving the heat transfer and the phase transformation efficiency, such as high static pressure water thawing, vacuum thawing, high humidity air thawing and the like; and secondly, electromagnetic energy penetration transfer and electromagnetic heat conversion are introduced, and the thawing is tried to be accelerated by breaking through the heat transfer limitation of the frozen meat body, such as radio frequency thawing, ohmic heating thawing, high-voltage electrostatic thawing and the like. In addition, researchers combine several technical ideas to establish a combined thawing technical scheme. Experimental research proves that the accelerated thawing methods have technical feasibility and advantages; but are limited in one or more respects, in terms of equipment cost, operational safety, and facility of use and maintenance of the equipment.

Ohmic heating is a novel heating mode that the material body to be heated is used as a conductive medium, and the heating effect is realized by the ohmic heat effect generated when current passes through the material, and the heating effect is not limited by the heat conduction characteristic and the heat transfer resistance of the material. The technology is favorable for realizing uniform and efficient heating of materials, so the technology is also applied to the accelerated thawing of frozen meat. Utility model patent CN 208370816U relates to an ohmic heating frozen meat thawing apparatus including parts such as cup, end cap, copper, titanium polar plate unfreeze. When in unfreezing, the large block shaped cylindrical frozen meat is put into the unfreezing device, the plug is screwed down to ensure that the upper and lower polar plates are fully contacted with the upper and lower planes of the frozen meat, and then the unfreezing is started after the power is switched on. In the unfreezing process of the device, the temperature difference between the inside and the outside of frozen meat is small, the unfreezing is uniform, the loss of heating and unfreezing nutritional ingredients is less, and before the meat is unfrozen, the meat needs to be cut to be fully attached to the electrode. Utility model patent CN 214257872U relates to an ohmic heating boiling device suitable for shellfish aquatic products, including parts such as preheating device, heating cabinet, delivery box. The device is used for stewing the shellfish aquatic products, has quick temperature rise and uniform heating, can ensure beautiful color and luster of the processed shellfish products, and does not influence the texture of the products.

The ohmic heating technology reported at present is applied to the accelerated thawing of frozen meat, and generally fails to solve a series of technical problems:

the thawing temperature uniformity was poor. Ohmic heating unfreezes and adopts the parallel plate electric field structure usually, when arranging the frozen meat in between the parallel electrode board circular telegram, often influences the abundant contact of frozen meat and electrode board because of the natural geometry difference of frozen meat or surface unevenness, leads to the electric current to pass through from frozen meat part to can't realize the even heating. At present, the main solution is to cut the frozen meat into a regular adaptive shape and place the meat in an electric field for thawing, but the complexity of the operation is greatly increased.

The risk of electrode contamination is high. In the unfreezing process, protein, fat, saccharides and inorganic salt in the frozen meat run off, so that the surface of an electrode plate is easily polluted, and the problems of electric field characteristic change and electrode plate corrosion are caused; corrosion of the electrode material will also give rise to a risk of contamination of the thawed meat by heavy metal elements in the electrode.

The generality of the unfreezing materials is not enough. The method is difficult to be widely suitable for various thawing scenes such as thawing of various animal species, various tissue parts and multiple pieces of meat in the same batch.

Disclosure of Invention

In order to solve all or part of the problems in the ohmic heating and unfreezing of the frozen meat, the invention provides a frozen meat unfreezing device based on a flexible electrode.

The invention relates to a frozen meat thawing device based on a flexible electrode, which comprises: the thawing pool can be used for containing thawing solution; the two parallel guide rails are positioned on two sides of the thawing pool and longitudinally extend in the horizontal direction; two paired electrode plate assemblies each configured to be vertically and slidably spanned between two guide rails by its electrode backing plate for ohmic heating of the frozen meat between the two electrode plate assemblies; and the U-shaped net rack is configured to be arranged on the two guide rails in a sliding way through two net rack hanging rods transversely erected between the two guide rails and positioned between the two flexible electrode plate assemblies, and is used for containing the frozen meat for ohmic heating. Wherein the electrode plate assembly includes a flexible electrode attached to an electrode backing plate for substantially conforming to frozen meat contained within the U-shaped rack during ohmic heating.

The thawing apparatus according to the embodiment of the present invention, wherein the lower part of the thawing bath further comprises at least one guide rail to slidably support the electrode plate assembly from below.

According to the thawing apparatus of the embodiment of the invention, each electrode plate assembly comprises a metal electrode sheet and a flexible layer which are sequentially laminated on one surface of an electrode backing plate to constitute the flexible electrode.

According to the thawing device provided by the embodiment of the invention, the refrigeration heat exchange fin is attached to the other surface of each electrode lining plate and is used for cooling the metal electrode plates.

According to the thawing apparatus of the embodiment of the invention, the flexible layer is the conductive hydrogel fixed on the metal electrode sheet, and preferably, the thickness of the flexible layer is set to be not less than the difference between the maximum thickness and the minimum thickness of the frozen meat to be thawed.

According to the unfreezing device provided by the embodiment of the invention, the U-shaped net rack comprises the flexible net, and two opposite side edges of the flexible net are respectively hung on the hanging rods of the two net racks to form a U shape.

The thawing apparatus according to the embodiment of the present invention, wherein the flexible net woven from the thin wires includes a plurality of lengths of stopper strings having a smaller elasticity than the thin wires to divide the flexible net into a plurality of relatively independent frozen meat receiving spaces.

According to the thawing apparatus of the embodiment of the present invention, the electrode lining and/or the rack hanging rod is slidably fitted with the guide rail by the shape fitting portions at both ends thereof, preferably, wherein the shape fitting portions are upper concave portions at both ends of the electrode lining and/or the rack hanging rod.

According to the thawing device of the embodiment of the invention, the locking component is arranged on the guide rail or on the electrode lining plate and the net rack hanging rod to prevent the electrode plate component and/or the U-shaped net rack from sliding on the guide rail.

According to the thawing apparatus of the embodiment of the present invention, the locking member is an annular locking member arranged around the guide rail and configured to be screwed to travel along the guide rail in cooperation with the guide rail.

Drawings

The invention will be more clearly understood from the following detailed description taken in conjunction with the accompanying drawings, in which:

fig. 1 is a schematic top view of a thawing apparatus according to an embodiment of the present invention, which is in a use state.

Fig. 2 is a left side schematic cross-sectional view of the device of fig. 1.

FIG. 3 is a further left side schematic cross-sectional view of the apparatus of FIG. 1 showing the electrode assemblies mounted on two parallel rails on the upper portion of the thawing cell.

Fig. 4 is a left side schematic view of the apparatus of fig. 1 showing a U-shaped rack mounted on two parallel rails above the thawing tank.

Detailed Description

The ohmic heating technology utilizes the ohmic effect of the substance body to generate heat, and has the advantages that the energy received in the substance is improved, and meanwhile, the substance is not connected with the electrode by a heat exchange medium. The invention uses ohmic electrodes to unfreeze the frozen meat placed between the ohmic electrodes.

The frozen meat thawing device based on the flexible electrode comprises a thawing pool, a pair of (two) parallel guide rails positioned on two side edges of the upper part of the thawing pool, a pair of electrode plate assemblies vertically and slidably erected (inserted) on/between the two parallel guide rails, and a U-shaped net rack slidably erected on the two parallel guide rails and positioned between the pair of electrode plate assemblies. When the thawing operation is performed, the electrode plate assembly and the U-shaped net frame can be fixed relative to the two parallel guide rails by the locking members to prevent the electrode plate assembly and the U-shaped net frame from sliding on the parallel guide rails, frozen meat can be placed in the U-shaped net frame, and ohmic heating is performed by the electrode plate assemblies on the two sides. The lower portion of the thawing bath may additionally comprise at least one lower side parallel guide rail to further slidably (or fixedly with a locking member) support the electrode plate assembly from below. The thawing device is also provided with a voltage-regulating alternating current power supply system for supplying power to the electrode assembly.

Specifically, the thawing pool 1 shown in fig. 1 is an insulating cubic pool body with an upward opening, and the upward opening is equipped with a cover door which can be opened and closed, three parallel guide rails 9 made of bakelite materials extending along the ohmic heating electric field direction are arranged in the thawing pool, and the thawing pool is placed perpendicular to the x direction, wherein two of the guide rails are arranged on two sides of the upper part of the thawing pool 1, and one of the guide rails is arranged in the middle of the lower part of the thawing pool 1 and is used for slidably supporting a pair of electrode plugboards 3a and a pair of grid plugboards (grid hanging rods) 3 b. The two types of boards 3a and 3b are placed parallel to the x-direction, i.e. perpendicular to the parallel guide 9. The paired flexible electrodes are respectively attached to the inner sides (the sides facing the heated and frozen meat) of the two electrode insertion plates 3a to form paired electrode plate assemblies. Two opposite sides of the net 8 are respectively attached (e.g., hung or sewn) to two net rack hanging rods 3b, thereby forming a U-shaped net rack suitable for placing frozen meat. Each insert plate may be fixed to the parallel guide rails by locking members 7.

Specifically, as shown in fig. 1 and 2, each of the two electrode plate assemblies includes an electrode insertion plate (electrode lining plate) 3a, a metal electrode plate 5 and a flexible layer 6 which are sequentially stacked on the inner side of the electrode insertion plate 3a, and preferably, a refrigeration heat exchange plate 4 attached to the outer side of the electrode insertion plate 3 a. The metal electrode sheet 5 and the flexible layer 6 constitute a flexible electrode. The electrode insert plate 3a is used to mount the flexible electrode assembly on parallel guide rails 9 (described in detail later with reference to fig. 4). The metal electrode plate 5 is connected with a voltage-regulating alternating-current power supply. The electrically conductive flexible layer 6 is intended to fit the meat mass 2 to be thawed. Preferably, the thickness of the flexible layer may be set to be not less than the difference between the maximum thickness and the minimum thickness of the meat to be thawed. The refrigeration heat exchange fins 4 covered on the outer side of the electrode inserting plate 3a are used for cooling the metal electrode plates 5.

The main body of the flexible layer material is natural macromolecular conductive gel formed by polysaccharide, protein or a compound of polysaccharide and protein, can be gel embedded in gaps of food-grade porous fiber materials, can also be gel wrapped by food-grade mesh cloth, and can also be a food-grade conductive gel body. Or the main material of the flexible layer is hydrogel of carrageenan, gelatin, agar, alginic acid, hyaluronic acid, modified starch, modified cellulose and a compound thereof, and preferably hydrogel compounded by carrageenan and gelatin. The hydrogel can be poured and solidified on the metal electrode sheet, can be adhered by using an adhesive, and can be coated and fixed on a supporting layer (an electrode inserting plate or a metal electrode sheet) by using a nylon net (for example, the same net as a U-shaped net rack) so as to enhance the durability of the gel. The gel can be repeatedly used until the frozen meat can not be tightly attached due to the breakage.

In particular, as shown in figures 1 and 3, the electrode plate assembly rests with the two shoulders (lateral ends or lateral projections) of the insert plate 3a between pairs of parallel rails 9 in the upper part of the thawing tank 1. The shoulder of the insert plate 3a preferably has a positioning recess (e.g., a semicircular recess) that is a sliding fit with the parallel guide rail 9. When the lower part of the electrolytic cell 1 is provided with parallel guide rails 9, the lower side edge of the insert plate 3a can be correspondingly provided with a positioning concave part which is matched with the insert plate in a sliding way, as shown in figure 3. The shoulder of the electrode insert plate 3a may be secured to the parallel guide rail 9 by a locking member 7.

According to the embodiment shown in the figure, the locking members 7 are provided on the guide rails 9 at the inner and outer side positions of each electrode assembly, and the locking members 7 may be provided only at the outer side positions. The locking member 7 may be an annular member arranged around the parallel guide rails and movable along the guide rails. The locking member 7 may be screw-fitted to the guide rail (in particular, the annular locking member 7 has an internal thread which engages with an external thread on the guide rail, not shown in the figures) so that it can be advanced along the guide rail 9 by screwing the locking member 7 to a desired position to press or lock the position of the electrode insert plate 3a on the guide rail 9 as required. The radial outer side of the locking component 7 is provided with a stressed handle or a gear so as to be screwed in manually or electrically.

Based on the above disclosure, one skilled in the art may also contemplate the use of other forms of locking members. For example, the insert plate is fixed by providing a spring mechanism, an insertable stopper, or an insertable bayonet on the guide rail between the insert plate and the inner wall of the thawing groove. It is also possible to provide a through-hole at the shoulder of the electrode insert plate reaching into the positioning recess, through which a locking member 7, such as a bolt, screw or the like, can be fitted or screwed and engage with the parallel guide rail surface to fasten the respective shoulder relative to the parallel guide rail, so that the pair of electrode plate assemblies can be fastened to the parallel guide rail at the desired distance at the start of the defrosting operation. The ease of operation, pressure controllability, and material suitability of the locking mode of the illustrated embodiment are all applicable to the present invention.

Specifically, as shown in fig. 1 and 4, the U-shaped net frame is composed of a pair of net frame hanging rods 3b and a flexible net 8 (e.g., a net woven with nylon thread), and the net 8 is hung on/between the pair of net frame hanging rods 3b with opposite side edges (e.g., a plurality of drawing holes are arranged on the insertion plate 3b for connecting the flexible net 8, see fig. 4), thereby forming the U-shaped net frame. As shown in fig. 4 and 3, the rack hanging bar 3b is narrower than the electrode insertion plate 3a, specifically, it is equivalent in shape and size to the upper portion of the electrode insertion plate 3a, and it can be slidably fitted with the parallel guide rail through positioning recesses at both end portions (shoulder portions or protruding portions) in a similar manner to the electrode insertion plate 3 a. A U-shaped grid is placed between the pairs of parallel electrode plate assemblies, is slidably adjustable in position along the guide rails and can be fixed relative to the parallel guide rails 9 by means of locking members 7 in a similar manner to the electrode plate assemblies. The mesh 8, which is U-shaped when assembled, is substantially horizontally aligned with the flexible electrode assembly or flexible electrode.

As shown in fig. 4, the flexible net 8 woven from a thin thread such as nylon thread 11 may also include a plurality of lengths of stopper rope 10 that have been divided into a plurality of regions, such as rectangular regions. For example, the stopper rope 10 is woven or sewn into the net 8 and has a higher strength or less elasticity than the fine thread 11. Whereby the stopper string divides the net 8 into a plurality of relatively independent frozen meat accommodating spaces. Therefore, as shown in fig. 2 and 4, when a plurality of pieces of frozen meat 2 are stuffed into the U-shaped net 8, the pieces of frozen meat tend to be packed into the U-shaped net frame in the narrowest manner (i.e., the thinnest manner in the electric field direction), and when the area partitioned by the stopper rope 10 is sufficiently small, the pieces of frozen meat can be reduced or prevented from overlapping each other in the electric field direction.

According to the above embodiment, a U-shaped net for carrying frozen meat is erected between the parallel flexible layers 6 on both sides, and the frozen meat 2 is placed in the U-shaped net and clamped by the flexible layers 6. The flexible layer can produce deformation in order to fully laminate irregular frozen meat when applying appropriate pressure, makes the electric current dispersion pass through frozen meat in order to improve the thawing temperature homogeneity, can satisfy the demand of thawing of irregular meat from this.

The frozen meat is restrained by the U-shaped net rack and is fastened by the flexible layer 6, so that the maximum projection area of the frozen meat is kept right opposite to the flexible electrode in the unfreezing process, an electric field can uniformly penetrate through the frozen meat, and the unfreezing efficiency is improved.

When in use, the low-temperature thawing solution can be selectively added into the thawing tank 1, and the component of the low-temperature thawing solution can be deionized water. In the thawing process, heat exchange occurs between the frozen meat 2 and the thawing solution, preventing local overheating of the surface of the frozen meat to maintain the meat quality. And starting a thawing solution circulating system, and enabling the thawing solution to enter and exit the thawing pool in a mode shown in the figure 1.

The refrigeration heat exchange plate 4 is attached to the outer side (the side far away from the frozen meat) of the flexible electrode inserting plate 3a in an insulating way, and a refrigerant enters and exits the refrigeration heat exchange plate through a pipeline (shown by a dotted line in figure 1). The refrigeration pipeline is a hose made of elastic silica gel.

The voltage-regulating alternating current power supply unit is connected with the metal electrode plate (shown by a solid line in figure 1), and can set proper electric field intensity according to different frozen meat tissue structures or thicknesses so as to obtain stable thawing effect.

In order to investigate the advantages of the thawing device and the method, the inventor proposes indexes for evaluating the meat thawing quality on the basis of relevant documents and a large number of experiments, including thawing time, nuclear temperature difference, nuclear surface temperature difference and weight loss rate. Wherein the nuclear temperature difference is the temperature difference measured at two different positions in the frozen meat core area; the core surface temperature difference is the temperature difference between the core area of the frozen meat and the surface of the frozen meat. The following operation steps are provided to implement index control and improve the meat thawing quality.

The device for unfreezing the meat can be implemented by the following steps:

(1) and (3) erecting a flexible electrode, namely selecting a plug board with a proper flexible electrode area according to the whole area of the frozen meat, and erecting the plug board on a parallel guide rail. The metal electrode plate is connected with a power supply. The optimized area of the flexible electrode is beneficial to the electric field to uniformly penetrate through the frozen meat so as to enhance the uniformity of the thawing temperature and shorten the thawing time;

(2) the frozen meat is guided to be loaded, the unpacked frozen meat is divided into grids and placed in a U-shaped net rack, and the maximum projection area of the frozen meat is opposite to the electrode side. Electric field concentration is facilitated, and the thawing time is shortened;

(3) the U-shaped net rack is installed, the distance between the flexible electrodes is increased, the U-shaped net rack is vertically inserted into the U-shaped net rack, and the U-shaped net rack is erected on the parallel guide rails and is perpendicular to the parallel guide rails.

(4) Fixing, namely adjusting the positions of the paired flexible electrodes to clamp the frozen meat, screwing in the pressurizing and locking component to fix the positions of the paired flexible electrodes, and ensuring that the flexible electrodes clamp the frozen meat and are fully attached to the frozen meat;

(5) and starting the refrigeration heat exchange system to enable the refrigerant to flow through the refrigeration heat exchange sheet at a constant speed and keep the temperature of the flexible layer on the flexible electrode not higher than 10 ℃. The redundant heat of the electrode plate is taken away in time, and the flexible layer is prevented from being melted by local high temperature;

(6) supplying power for thawing, setting the power supply voltage of an alternating current power supply, and starting the power supply and thawing processes;

(7) completing the unfreezing, operating the equipment until the meat is unfrozen to a required state (for example, the temperature at the core of the frozen meat reaches more than 4 ℃), and turning off the power supply of each system; screwing out the pressurizing locking mechanism to loosen the electrode plate and the U-shaped net frame, lifting the U-shaped net frame upwards and taking out the unfrozen meat; inserting another U-shaped net frame with the frozen meat placed between the paired electrode plates;

(8) for frozen meat with non-uniform shape, size or tissue structure height, circulating and refrigerating deionized water can be introduced into the thawing pool in the thawing process, so that the whole process and the whole range of the thawing system are within 10 ℃. The thawing solution and the frozen meat generate heat convection, and the thawing temperature uniformity is further improved.

And (4) repeating the steps (4) to (8) to implement the next batch of unfreezing operation.

The following is a specific thawing operation test.

Example 1: by adopting the device and the method, the chicken breast is taken out from a refrigeration house with the temperature of-20 ℃. Under the condition of room temperature (about 20 ℃), selecting a flexible electrode matched with the projected area of the chicken breast, placing the single-layer chicken breast on a U-shaped net frame, and then performing the operation according to the thawing operation steps. The device is operated until the meat is completely thawed (for example, the temperature at the core of the frozen meat reaches more than 4 ℃), the time for thawing the frozen meat is measured to be 6.85min/200g, the temperature difference between the core and the nucleus of the meat is measured to be 2.1 ℃, the temperature difference between the surface and the nucleus is measured to be 3.8 ℃, and the weight loss rate of the chicken is 1.3 percent after thawing is completed.

Comparative example 1: by adopting the device and the method of the invention (but eliminating the flexible layer of the electrode), the chicken breast is taken out from a cold storage with the ambient temperature of-20 ℃. Under the condition of room temperature, a stainless steel electrode plate (without a flexible layer) matched with the projection area of the chicken breast is selected, and after the single-layer chicken breast is placed on a U-shaped net frame, the operation is carried out according to the unfreezing operation steps. The device is operated until the meat is completely thawed, the time for thawing the frozen meat is measured to be 7.13min/200g, the nuclear temperature difference of the meat is measured to be 27.6 ℃, the nuclear surface temperature difference is measured to be 42.7 ℃, and the weight loss rate of the meat is 3.1 percent after thawing is completed. After the experiment, protein denaturation occurs in the chicken part area due to overhigh temperature, and the metal electrode plate is seriously polluted.

In the comparative example 1, a stainless steel electrode plate is selected, and experimental comparison shows that the thawing time of frozen meat is slightly prolonged, but the temperature uniformity is obviously reduced, and partial regions are subjected to protein denaturation due to overhigh temperature, and the metal electrode plate is seriously polluted. Therefore, the adoption of the flexible electrode can obviously improve the thawing temperature uniformity and simultaneously reduce the corrosion of the metal electrode plate; the adoption of the flexible electrode can effectively shorten the thawing time and reduce the weight loss rate of chicken.

Example 2: by adopting the device and the method, the complete hind leg meat (containing muscle, fat and epidermal tissue) of the pig with the skin is taken out from a refrigeration house at the temperature of-20 ℃. Under the condition of room temperature, the frozen pork back leg meat is placed in a U-shaped net rack, and the frozen pork back leg meat is clamped by a flexible electrode and fixed by a pressurizing locking mechanism. The device is operated until the meat is completely thawed, the time for thawing the frozen meat is measured to be 8.74min/200g, the nuclear temperature difference of the meat is measured to be 3.2 ℃, the nuclear surface temperature difference is 4.9 ℃, and the weight loss rate of the pork hind leg meat is 2.5 percent after thawing.

Comparative example 2: by adopting the device and the method of the invention (but the U-shaped net rack is removed, and the frozen meat is directly loaded), the integral hind leg meat (containing muscle, fat and epidermal tissue) of the pigskin is taken out from a refrigeration house with the temperature of 20 ℃ below zero. Under the condition of room temperature, the frozen pork hind leg meat is loaded without restriction, and the frozen pork hind leg meat is directly clamped by a flexible electrode and fixed by a pressurizing locking mechanism. The device is operated until the meat is completely thawed, the time for thawing the frozen meat is measured to be 19.28min/200g, the nuclear temperature difference of the meat is measured to be 6.1 ℃, the nuclear surface temperature difference is 9.6 ℃, and the weight loss rate of the pork hind leg meat is 4.4 percent after thawing.

Comparative example 3: by adopting the device and the method of the invention (but eliminating the electrode plate locking mechanism), the integral hind leg meat (containing muscle, fat and epidermal tissue) of the pig with the skin is taken out from a refrigeration house at the temperature of 20 ℃ below zero. Under the condition of room temperature, placing the frozen pork back leg meat in a U-shaped net rack, and placing the frozen pork in a way that the maximum projection area is opposite to the flexible electrode; the flexible electrode plates are closed and attached to the U-shaped net rack, but no locking mechanism is used for keeping clamping. The device is operated until the meat is completely thawed, the time for thawing the frozen meat is measured to be 24.23min/200g, the nuclear temperature difference of the meat is measured to be 6.7 ℃, the nuclear surface temperature difference is 8.2 ℃, and the weight loss rate of the pork hind leg meat is 3.6 percent after thawing.

Comparative example 4: by adopting the device and the method (without cooling the electrode by the refrigeration heat exchange sheet), the integral pigskin hind leg meat (containing muscle, fat and epidermal tissue) is taken out from a refrigeration house at the temperature of-20 ℃. Under the condition of room temperature, the frozen pork back leg meat is placed in a U-shaped net rack, and the frozen pork back leg meat is clamped by a flexible electrode and fixed by a pressurizing locking mechanism. The device is operated until the meat is completely thawed, and the circulation of the cooling liquid in the refrigeration heat exchange sheet is closed in the period. In the experimental process, the local temperature of the electrode plate is too high, so that the flexible layer is melted, and the unfreezing operation is not finished.

And (3) knotting: above-mentioned control example 2 is with freezing meat unconstrained loading, and the experiment contrast discovery thawing time obviously increases, and frozen meat can't keep the direction type in the electric field to place, and the unable flexible electrode that laminates of pig back leg meat leads to local overheat, and the thawing temperature homogeneity reduces. Comparative example 3 has no pressurization locking operation, and experimental comparison shows that the thawing time of frozen meat is increased, the pork hind leg meat is not tightly attached to the flexible electrode, the temperature uniformity is obviously reduced, and partial regions are over-high in temperature. In the comparative example 4, the circulation of the cooling liquid in the refrigeration heat exchanger is closed, the flexible layer is melted due to the local overheating of the metal electrode plate, and the thawing device fails. Therefore, the U-shaped net rack can effectively restrain the direction of the meat, the direction of the maximum projection area of the U-shaped net rack is opposite to the flexible electrode, and the uniform distribution of various tissues in the frozen meat in an electric field is improved to the maximum extent; the pressurizing locking mechanism can ensure that the flexible electrode can clamp the frozen meat, so that the flexible electrode can adapt to the surface shape of the frozen meat to deform to the maximum extent, and the thawing temperature uniformity can be improved; the cooling liquid circulation in the refrigerating layer can quickly take away more heat, so that the flexible layer is prevented from being melted by local high temperature, and the thawing is prevented from being influenced.

Example 3: by adopting the device and the method, a plurality of pieces of complete chicken breast meat with irregular shapes are taken out from a refrigeration house with the temperature of-20 ℃. Laying chicken breast in 2 layers in a U-shaped net rack at room temperature, and thawing. The device is operated until the meat is completely thawed, the time for thawing the frozen meat is measured to be 14.74min/200g, the average nuclear temperature difference of the meat is measured to be 3.2 ℃, the average nuclear surface temperature difference is measured to be 3.9 ℃ and the average weight loss rate of the chicken breast is 1.6 percent after thawing is completed.

Comparative example 6: by adopting the device and the method of the invention (but not using the U-shaped net rack), a plurality of pieces of whole chicken breast meat with irregular shapes are taken out from a refrigeration house with the temperature of-20 ℃. Under the condition of room temperature, the frozen chicken breast meat is loaded without restriction, and the chicken breast meat is directly clamped by a flexible electrode and fixed by a pressurizing locking mechanism. The device is operated until the meat is completely thawed, the time for thawing the frozen meat is measured to be 38.74min/200g, the average nuclear temperature difference of the meat is measured to be 34.9 ℃, the average nuclear surface temperature difference is measured to be 9.1 ℃ and the average weight loss rate of the chicken breast is 2.7 percent after thawing is completed.

And (3) knotting: the control example 6 has no constraint loading of frozen meat, and the experiment shows that the thawing time is obviously increased. Since the frozen meat pieces are randomly oriented, there is a local stacking and the gaps between the meat pieces are large, so that the difference in dielectric conditions of each region is significantly increased, resulting in a decrease in thawing temperature uniformity. In addition, the loading and discharging of frozen meat is cumbersome. Therefore, the frozen meat is restricted and loaded by the U-shaped net rack, the convenience of batch operation can be greatly improved, the maximum projection area of all meat is kept right to the flexible electrode in the whole process, and the thawing temperature uniformity is remarkably improved.

Example 4: by adopting the device and the method, a plurality of pieces of chicken leg meat (with bones) with different masses and shapes are taken out from a refrigeration house at the temperature of-20 ℃. Placing chicken breast in U-shaped net rack, adding deionized water at 10 deg.C until the frozen meat is submerged (thawing process is kept below 10 deg.C). The device is operated until the meat is completely thawed, the time for thawing the frozen meat is measured to be 9.26min/200g, the average nuclear temperature difference of the meat is measured to be 4.1 ℃, the average nuclear surface temperature difference is measured to be 5.8 ℃ and the average weight loss rate of the chicken leg meat is 1.8 percent after thawing is completed.

Comparative example 7: by adopting the device and the method, a plurality of pieces of chicken leg meat (with bones) with different masses and shapes are taken out from a refrigeration house with the ambient temperature of-20 ℃. And (3) placing the chicken breast on a U-shaped net frame at room temperature, and then performing thawing operation according to the thawing operation steps. The device is operated until the meat is completely thawed, the time for thawing the frozen meat is 17.63min/200g, the average nuclear temperature difference of the meat is 5.6 ℃, the average nuclear surface temperature difference of the meat is 8.5 ℃ and the average weight loss rate of the chicken leg meat is 3.9 percent after thawing is finished.

And (3) knotting: in the comparative example 7, the thawing solution is not added, and experimental comparison shows that the thawing time is obviously increased and the average weight loss rate is obviously increased. Therefore, the thawing time can be greatly shortened by adding the thawing solution, and the average weight loss rate can be reduced.

The above examples and comparative examples show that the device of the present invention is applicable to various kinds of meat including frozen meat with bones; for the meat with large difference of geometric shape and tissue structure, the device has excellent unfreezing effect; the device unfreezes effectually under the condition of not having the thawing solution, and temperature homogeneity further promotes after adding the thawing solution.

Advantages and positive effects of the invention

The arrangement mode of the parallel guide rails is matched with the design of the positioning concave parts of the inserting plates, so that the parallel guide rails and the inserting plates can be guaranteed to be perpendicular to each other all the time, and therefore the two flexible electrodes and the U-shaped net rack are parallel to each other all the time. The electric field is uniformly distributed and penetrates through the frozen meat, and the thawing temperature uniformity is improved.

The U-shaped net frame can be hung on the parallel guide rails in a sliding mode, the arrangement directions of a plurality of frozen meat in the same batch are restrained simultaneously, the maximum projection area of the frozen meat is enabled to be right opposite to the flexible electrode, the thawing temperature uniformity is improved, and the thawing time is shortened.

The combination of the flexible electrode and the parallel guide rail facilitates the insertion and the extraction of the flexible electrode and the replacement of the flexible electrode according to the integral size of the frozen meat; the flexible electrode can be slidably mounted on the parallel guide rails, the frozen meat can be fully clamped by the flexible electrode through distance adjustment, and an electric field is more concentrated; the positioning concave part can keep the two flexible electrodes parallel all the time, and the uniformity of an electric field environment is ensured.

But pressurization locking structure locking flexible electrode subassembly guarantees that flexible electrode presss from both sides tight frozen meat, is favorable to concentrating the electric field, extrudes the air of frozen meat contact area simultaneously, reduces resistance, improve equipment work efficiency.

The flexible layer, the metal electrode plate and the refrigeration heat exchange plate are attached to the inserting plate, so that the flexible electrode is convenient to take and place. Semicircular positioning concave parts matched with the parallel guide rails are arranged on two sides of the inserting plate, so that the flexible electrodes can be restrained to be always parallel; the metal electrode plates have a series of areas, are convenient to replace and are beneficial to the electric field to uniformly penetrate through the frozen meat; during the working period of the equipment, the temperature near the metal electrode plate is higher, the area of the refrigeration heat exchange sheet is consistent with that of the flexible layer, and the refrigeration heat exchange sheet is attached to the back of the metal electrode plate in an insulating way, so that redundant temperature can be effectively taken away, the temperature of the flexible layer on the flexible electrode is kept not higher than 10 ℃, the thawing temperature uniformity is favorably improved, and the local overheating of the surface of frozen meat is prevented; the thickness of the flexible layer is not less than the difference between the maximum thickness and the minimum thickness of the meat to be unfrozen, so that the flexible layer is suitable for the meat with irregular surface, and the equipment is ensured to be widely suitable for various raw materials.

Flexible layer material is constituteed, can take place deformation according to frozen meat shape after pressing from both sides tight frozen meat to satisfy the demand of irregular meat unfreezing, it is long when effectively shortening the unfreezing simultaneously, improve the temperature homogeneity that unfreezes. In addition, the flexible layer can prevent the metal electrode plate from directly contacting meat in the unfreezing process, and effectively reduces the corrosion of protein, grease and salt generated in the unfreezing process on the metal electrode plate.

The optimal flexible layer material composition can better fit the surface shape of frozen meat, adapts to extremely irregular raw materials on the surface, has better uniformity in the electric field environment, is favorable for shortening the thawing time and increasing the thawing temperature uniformity.

The U-shaped net frame is separated by the insulated flexible wires (limiting ropes), frozen meat is naturally squeezed tightly under the action of gravity, the orientation of a plurality of pieces of meat in an electric field can be restrained, the maximum projection area of the frozen meat is enabled to be right opposite to the flexible electrode, and the electric field is facilitated to uniformly penetrate through the frozen meat. In addition, the nylon net can hold scattered meat blocks in the unfreezing process, and equipment pollution is reduced.

The flow direction of the unfreezing liquid is parallel to the flexible electrode, so that the unfreezing liquid is suitable for thermal convection between the surface of frozen meat and the unfreezing liquid, and the unfreezing temperature uniformity is favorably improved.

Claims (10)

1. A frozen meat thawing device based on a flexible electrode comprises:

the thawing pool can be used for containing thawing solution;

the two parallel guide rails are positioned on two sides of the thawing pool and longitudinally extend in the horizontal direction;

two paired electrode plate assemblies each configured to be vertically and slidably spanned between two guide rails by its electrode backing plate for ohmic heating of the frozen meat between the two electrode plate assemblies; and

a U-shaped net rack, two net rack hanging rods which are transversely arranged between the two guide rails and are arranged on the two guide rails in a sliding way and positioned between the two flexible electrode plate assemblies for containing the frozen meat for ohmic heating,

wherein the electrode plate assembly includes a flexible electrode attached to an electrode backing plate for substantially conforming to frozen meat contained within the U-shaped rack during ohmic heating.

2. The thawing apparatus of claim 1, wherein the lower portion of the thawing bath further comprises at least one guide rail to slidably support the electrode plate assembly from below.

3. The thawing apparatus as claimed in claim 1, wherein each electrode pad assembly comprises a metal electrode pad and a flexible layer sequentially laminated on one side of an electrode backing plate to constitute the flexible electrode.

4. Thawing apparatus as claimed in claim 3, wherein refrigeration heat exchanger fins are attached to the other side of each electrode pad for cooling the metal electrode sheets.

5. Thawing apparatus as claimed in claim 3, wherein said flexible layer is an electrically conductive hydrogel fixed on a metal electrode sheet, preferably the thickness of the flexible layer is set to be not less than the difference between the maximum thickness and the minimum thickness of the frozen meat to be thawed.

6. The thawing apparatus of claim 1, wherein the U-shaped net comprises a flexible net, opposite sides of which are respectively suspended from two net rack hanging rods to be U-shaped.

7. The thawing apparatus of claim 6, wherein the flexible net woven of strings comprises a plurality of lengths of restriction strings having a smaller elasticity than the strings to divide the flexible net into a plurality of relatively independent frozen meat receiving spaces.

8. Thawing apparatus as claimed in claim 1, wherein the electrode lining and/or the rack bar is slidably engaged with the guide rail by form-fitting portions at both ends thereof, preferably wherein the form-fitting portions are upper recesses at both ends of the electrode lining and/or the rack bar.

9. Thawing apparatus as claimed in any of the claims 1 to 8, wherein locking members are provided on the rails or on the electrode pad and the rack hanging bar to prevent the electrode pad assembly and/or the U-shaped rack from sliding on the rails.

10. The thawing apparatus of claim 9, wherein the locking member is an annular lock disposed about the rail and configured to threadably travel along the rail in cooperation with the rail.

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