Alternating current and direct current symbiotic electric field generating device and application in food freezing and unfreezing

Abstract

The invention discloses an alternating current and direct current symbiotic electric field generating device and application thereof in food freezing and unfreezing. The electric field generating device comprises an internal structure and an external structure. The internal structure comprises a solid ratio high-voltage boosting transformer (1), a rectifier bridge (2), a safety resistor (3) and a coupling capacitor I (41); the external structure comprises a first discharge electrode (51), a first acrylic plate (61) and a metal storage plate (7). The electric field generating device can generate a space type high-voltage electrostatic field and a contact type high-voltage alternating electric field at the same time. The food is frozen and unfrozen by using the alternating-current and direct-current symbiotic electric field generating device. The method comprises the following steps: freezing fresh prawns in a freezing chamber loaded with a space type high-voltage electrostatic field; and putting the prawns frozen by the high-voltage electrostatic field into an unfreezing chamber loaded with a contact type high-voltage alternating electric field for unfreezing. According to prawns which are frozen and unfrozen under the assistance of the alternating-current and direct-current symbiotic electric field generating device, the freezing and unfreezing time is obviously shortened, juice loss is obviously reduced, muscle fiber structures are kept relatively complete, and the storage quality is obviously improved.

Description

Technical Field

[0001] The present invention relates to the technical field of food freezing and thawing, and in particular to an AC / DC symbiotic electric field generating device and a food freezing and thawing method. Background Art

[0002] High-voltage electric field technology is a new type of non-thermal processing technology, which is mainly divided into direct current electric field (electrostatic field) and alternating current electric field (alternating electric field). High-voltage electric field technology has the advantages of enhanced heat and mass transfer, wide application range, and low energy consumption. Therefore, a large number of studies have focused on the application of high-voltage electric field technology in food processing, and it has been proven that high-voltage electric field technology can effectively reduce harmful changes in food quality and nutrition, and help maintain the physical and sensory properties of food. In recent years, the application of high-voltage electric field technology in food has covered many fields such as preservation, thawing, and drying, and has shown good application prospects. Studies have shown that high-voltage electric fields can effectively inhibit the activity of various enzymes in food processing, slow down the growth of microorganisms, extend the shelf life of food, and improve the quality of food during storage. Therefore, high-voltage electric field technology will be a promising food processing technology with a wide range of applications.

[0003] Freezing and thawing are important links in the transportation and production of aquatic products. However, the irregular ice crystals formed during the freezing process can seriously damage the cell and protein structure of the food, affecting the quality of the food during storage. In addition, the quality of food storage is also closely related to the thawing technology. As the thawing time increases, there will often be problems such as a large amount of water loss, protein denaturation, and decreased sensory quality. Existing studies have reported that high-voltage electrostatic fields can promote the directional arrangement of water molecules and control the size of ice crystal nucleation, thereby reducing ice crystal damage to muscle fibers and shortening the freezing time. At the same time, high-voltage alternating electric fields can directly destroy the steady-state structure of ice crystals, causing the hydrogen bonds of the ice layer structure to collapse, thereby shortening the thawing time. It is now widely used in the thawing of livestock meat.

[0004] Although there have been many reports on the theory and research of high-voltage electric fields, and their unique application advantages have been demonstrated. However, the application of high-voltage electric fields has certain limitations. First, different types of high-voltage electric fields and their modes of action are suitable for different application scenarios, and the existing electric field equipment has the defect of only being able to output one type of electric field. At the same time, the existing electric field has a relatively single mode of action, which will greatly limit the application of high-voltage electric fields in different fields. Secondly, the application scenarios of electric field equipment are single, and the advantages of AC and DC electric fields in the field of food processing cannot be brought into play at the same time. Summary of the invention

[0005] The purpose of the present invention is to provide an AC / DC symbiotic electric field generating device in view of the deficiencies of the existing technology and research, so as to form a spatial high-voltage electrostatic field and a contact-type high-voltage alternating electric field in a certain closed space, increase the scope of application of the electric field device, broaden its application field, and improve its ease of use.

[0006] Another object of the present invention is to provide an application of the electric field device in the field of food freezing and thawing. By freezing under high-voltage electrostatic field conditions and thawing under high-voltage alternating electric field conditions, the freezing and thawing time of food is shortened, the loss of juice is reduced, and the food maintains better quality after freezing and thawing.

[0007] The present invention provides an AC / DC symbiotic electric field generating device, the internal structure of which includes a solid-ratio step-up transformer, a safety resistor, a rectifier bridge, and a coupling capacitor. The solid-ratio step-up transformer is a 220 V to 5000 V solid-ratio step-up transformer with an operating frequency of 50-60 Hz; the rectifier bridge can convert high-voltage AC power into high-voltage DC power; the safety resistor is composed of a high-resistance resistor and a leakage protector in series, which controls the current within the human safety limit range (0-0.5 mA) to avoid the risk of electric shock; the coupling capacitor can filter DC signals and provide overvoltage protection.

[0008] The electric field release electrode includes an insulated wire and a discharge electrode. The discharge electrode is an aluminum alloy plate electrode, and the surface is insulated and protected by an acrylic plate. The discharge electrode is located inside the refrigerator and is connected to the electric field generating device through the insulated wire.

[0009] Preferably, the electric field generating device can generate high-voltage direct current and high-voltage alternating current simultaneously.

[0010] Preferably, there are two discharge electrodes, which are respectively located at the top of the freezing chamber and the bottom of the thawing chamber.

[0011] Preferably, the 220 V mains electricity is boosted by a booster and converted by a rectifier into 5000 V high voltage direct current and output to the discharge electrode at the top of the freezing chamber, forming a spatial electrostatic field in the closed space.

[0012] Preferably, a partition is provided in the freezing chamber, and a metal storage plate is provided at the bottom; the discharge electrode is spaced a certain distance from the metal storage plate, and the position of the discharge electrode is adjustable (10 cm, 15 cm, 20 cm); the metal storage plate is connected to the ground through a wire, and the electric potential is always 0, so that a uniform high-voltage electrostatic field is formed in the closed space.

[0013] Preferably, the 220 V mains electricity is boosted by a booster to 5000 V high-voltage alternating current and output to a discharge electrode at the bottom of the thawing chamber. The upper portion of the discharge electrode is double-insulated with an acrylic plate. The food to be thawed is in indirect contact with the discharge electrode through the acrylic plate, forming a contact-type high-voltage alternating electric field.

[0014] The present invention also provides the application of the AC / DC symbiotic electric field generating device in food freezing and thawing, specifically providing a method of saving energy and achieving good freezing and thawing effects by changing the electric field voltage and freezing temperature in a stepwise manner.

[0015] The application of the AC / DC symbiotic electric field generating device provided by the present invention in food freezing and thawing specifically comprises the following steps:

[0016] S1. Apply fluidized ice on the surface of fresh aquatic products, place them in a freezing chamber equipped with a spatial high-voltage electrostatic field device, adjust the voltage of the electrostatic field to 0.5-1.5KV, adjust the temperature to -2 to -5°C, and the treatment time to 1-3h;

[0017] S2, adjusting the electric field voltage of step S1 to 4.0-5 KV, the temperature to -16--18°C, and the processing time to 20-40 min;

[0018] S3, adjusting the electric field voltage of step S1 to 1.0-3KV, adjusting the temperature to -2--5°C, and the processing time to 1-2h.

[0019] The application of the AC / DC symbiotic electric field generating device provided by the present invention in food freezing and thawing specifically comprises the following steps:

[0020] S1. Place the frozen aquatic products in a thawing chamber equipped with a spatial high-voltage electrostatic field device, adjust the voltage of the electrostatic field to 4.0-5.0KV, adjust the temperature to -10~-5℃, and the processing time to 20-30min;

[0021] S2, lowering the electric field voltage of step S1 to 3.0-4KV, adjusting the temperature to -4°C, and processing time to 20-40min;

[0022] S3, adjusting the electric field voltage of step S1 to 1.0-3KV and the temperature to 0-5°C until thawing is completed.

[0023] Furthermore, through research, it was found that the voltage increase process is the time when energy consumption is high, especially from low voltage to high voltage. By taking a gradient increase and slow increase method, the freezing and thawing effect can be ensured while minimizing computer consumption.

[0024] Beneficial effects of the present invention:

[0025] Firstly, the present invention can simultaneously generate and output high-voltage direct current and high-voltage alternating current. By arranging a plate-type discharge electrode connected to an electric field generating device in a refrigerator or freezer, a high-voltage electrostatic field and a high-voltage alternating electric field are simultaneously generated in the space, thereby achieving the purpose of electrostatic field-assisted freezing and alternating electric field-assisted thawing.

[0026] Secondly, the electric field generating device described in the present invention has good safety in use. On the one hand, it adopts a weak current form, and the output current is only about 0.5 mA, which will not cause potential harm to the human body. On the other hand, the outside of the electrode plate is insulated, and it is not in direct contact with the food to avoid the risk of electric shock to the human body. The method of electric field assisted freezing and thawing has the advantages of being green and environmentally friendly, highly safe, and low-cost. At the same time, it is easy to industrialize and mass-produce, and has good commercial application prospects.

[0027] Finally, the present invention provides a freezing and thawing method, which can significantly shorten the freezing and thawing time of food, reduce the damage of ice crystals to the tissue structure, reduce the loss of juice after freezing and thawing, and improve the sensory quality after freezing and thawing.

[0028] Other advantages, objectives, features, etc. of the present invention will be reflected in part through the following description, and in part will be understood by those skilled in the art through study and practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 It is a schematic diagram of the electric field generating device of the present invention;

[0030] Figure 2 A time-temperature curve comparison diagram of the shrimp freezing method provided by the present invention and a common freezing method;

[0031] Figure 3 A time-temperature curve comparison diagram of the shrimp thawing method provided by the present invention and a common thawing method;

[0032] Figure 4 A scanning electron microscope structure diagram of fresh prawn muscle according to an embodiment of the present invention;

[0033] Figure 5 The scanning electron microscope structure diagram of the muscle after thawing by the freezing and thawing method of the prawn provided by the present invention;

[0034] Figure 6 This is a scanning electron microscope structure of shrimp muscle after thawing using the ordinary freeze-thaw method.

[0035] In the figure:

[0036] Solid-state high-voltage step-up transformer 1, rectifier bridge 2, safety resistor 3, coupling capacitor 1 41, coupling capacitor 2 42, discharge electrode 1 51, discharge electrode 2 52, acrylic plate 1 61, acrylic plate 2 62, metal storage plate 7, freezing chamber 8, and thawing chamber 9. DETAILED DESCRIPTION

[0037] The present invention is further described in detail below with reference to examples and drawings so that those skilled in the art can implement the invention with reference to the description.

[0038] Example 1

[0039] This embodiment provides an AC / DC symbiotic electric field generating device, such as Figure 1 As shown, the electric field generating device includes an internal structure and an external structure. The internal structure mainly includes a solid-state high-voltage step-up transformer 1, a rectifier bridge 2, a safety resistor 3, and a coupling capacitor, wherein the coupling capacitor includes a coupling capacitor 1 41 and a coupling capacitor 2 42.

[0040] The external structure mainly includes a discharge electrode, an acrylic plate, and a metal storage plate 7. The acrylic plate includes an acrylic plate 1 61 and an acrylic plate 2 62. The internal structure of the electric field generating device is located outside the refrigerator and is connected to the discharge electrode through an insulated wire. The external structure of the electric field generating device is located inside the refrigerator.

[0041] The electric field generating device can generate high-voltage direct current and high-voltage alternating current at the same time. The 220 V mains electricity is boosted to high-voltage 5000 V alternating current by the booster 1, converted to high-voltage direct current by the rectifier bridge 2, and then output to the discharge electrode through the safety resistor 3 to form a high-voltage electrostatic field; the 220 V mains electricity can also be boosted to high-voltage 5000 V alternating current by the booster 1, and directly output to the discharge electrode through the safety resistor 3 to form a high-voltage alternating electric field; the coupling capacitor provides direct current filtering and overvoltage protection.

[0042] The discharge electrodes are two plate electrodes, including a discharge electrode 1 51 and a discharge electrode 2 52, which are respectively located on the upper layer of the freezing chamber 8 and the bottom of the thawing chamber 9, and are made of aluminum alloy, and are insulated by acrylic plates on both sides. A crossbeam and a partition bracket are installed on the side of the freezing chamber 8 box body to adjust the distance between the discharge electrode 1 51 and the metal storage plate 7. The metal storage plate 7 is an aluminum alloy plate, which is connected to the ground through a wire so that its potential is always 0, forming a stable and uniform high-voltage electrostatic field inside the freezing chamber 8 space. The aquatic products to be frozen are placed above the metal storage plate 7, with a certain spatial distance from the discharge electrode 1 51 to avoid leakage, enhance the safety of use, and broaden the scope of application.

[0043] An acrylic plate 62 is installed above the discharge electrode 52 at the bottom of the thawing chamber 9. The aquatic product to be thawed is in indirect contact with the discharge electrode 52 through the acrylic plate 62, forming a contact-type high-voltage alternating electric field, which effectively enhances the destructive effect of the electric field force on ice crystals and prevents the aquatic product from directly contacting the discharge electrode to cause electric shock.

[0044] When using the present invention, fresh shrimps are first placed on the metal storage plate 7 of the electric field generating device, the temperature of the freezing chamber 8 is adjusted to -24°C for freezing, 220 V mains electricity is connected, the high-voltage electrostatic field switch is turned on, and the device starts freezing. The temperature of the thawing chamber 9 is adjusted to 4°C, the shrimps to be thawed are placed above the acrylic plate 62 of the electric field generating device, 220 V mains electricity is connected, the high-voltage alternating electric field switch is turned on, and the device starts thawing.

[0045] The electric field generating device can simultaneously generate a spatial high-voltage electrostatic field and a contact-type high-voltage alternating electric field to work. The output voltage of the electric field is 5000 V and the output current is 0.5 mA. It will not cause potential danger to the human body and broadens the scope of application of the electric field generating device.

[0046] Example 2

[0047] The embodiment of the present invention provides an application of an AC / DC symbiotic electric field generating device in food freezing and thawing. Taking shrimp as an example, freezing and thawing includes the following steps:

[0048] The application of the AC / DC symbiotic electric field generating device provided in this embodiment in food freezing and thawing, the freezing operation specifically includes the following steps:

[0049] S1. Apply fluidized ice on the surface of fresh aquatic products and place them in a freezing chamber equipped with a spatial high-voltage electrostatic field device. Adjust the voltage of the electrostatic field to 1KV, the temperature to -5°C, and the treatment time to 3h.

[0050] On the basis of ensuring the freezing effect, in order to save energy, the voltage is increased in a gradient manner, specifically by 0.2 KV every 10 minutes.

[0051] S2. The electric field voltage of step S1 is increased and adjusted to 4.0 KV, the temperature is adjusted to -16 to -18°C, and the processing time is 40 minutes; the method of increasing the voltage is to increase the voltage by 0.5 KV every 5 minutes.

[0052] S3. Reduce the electric field voltage of step S1 to 1.5 KV and adjust the temperature to -2°C until a freezing effect is achieved.

[0053] The application of the AC / DC symbiotic electric field generating device provided in this embodiment in food freezing and thawing, the thawing operation specifically includes the following steps:

[0054] S1. Place the frozen aquatic products in a thawing chamber equipped with a spatial high-voltage electrostatic field device, adjust the voltage of the electrostatic field to 4.5KV, adjust the temperature to -8°C, and process for 30 minutes. The method of increasing the voltage is to increase the voltage by 1KV every 5 minutes.

[0055] S2, lowering the electric field voltage in step S1 to 3.0 KV, adjusting the temperature to -4°C, and processing time to 40 min;

[0056] S3, adjusting the electric field voltage of step S1 to 1.0 KV and the temperature to 0-5°C until thawing is completed.

[0057] Experimental Example 1

[0058] Fresh shrimps were placed in a common freezing chamber without a high voltage electric field and frozen for 183-197 min.

[0059] Experimental Example 2

[0060] Fresh shrimps were placed in a freezing chamber loaded with a high voltage electrostatic field and frozen. The distance between the discharge electrode 51 and the metal plate 7 was 20 cm, and the freezing time was 124-144 min.

[0061] Experimental Example 3

[0062] Fresh shrimps were placed in a freezing chamber loaded with a high voltage electrostatic field and frozen. The distance between the discharge electrode 51 and the metal plate 7 was 15 cm, and the freezing time was 114-123 min.

[0063] Experimental Example 4

[0064] Fresh shrimps were placed in a freezing chamber loaded with a high voltage electrostatic field and frozen. The distance between the discharge electrode 51 and the metal plate 7 was 10 cm, and the freezing time was 111-117 min.

[0065] Experimental Example 5

[0066] Ordinary frozen shrimps were placed in an ordinary thawing chamber without an alternating electric field for thawing, and the thawing time was 262-301 min.

[0067] Experimental Example 6

[0068] The shrimp frozen with the aid of high-voltage electrostatic field were placed in a thawing chamber without a high-voltage electric field device for thawing, and the thawing time was 228-240 min.

[0069] By freezing the shrimp under spatial high-voltage electrostatic field conditions and thawing under contact high-voltage alternating electric field conditions, the freezing and thawing time of the shrimp can be effectively shortened, the juice loss of the shrimp after freezing and thawing can be reduced, the muscle fiber integrity of the shrimp after freezing and thawing can be maintained, and the quality of the shrimp after freezing and thawing can be improved.

[0070] The following is an analysis of the combined use of Experimental Example 4 and Experimental Example 6:

[0071] Materials: Fresh shrimp, weight 34.11±5.17 g. Treatment: Freeze at -24 ℃ for 5 h, thaw at 4 ℃ for 8 h.

[0072] Control group: non-electric field freezing and non-electric field thawing; Experimental group: 5000 V spatial high-voltage electrostatic field assisted freezing and 5000 V contact high-voltage alternating electric field assisted thawing.

[0073] Use a temperature recorder to collect the data of the change in the center temperature of the shrimp during freezing and thawing, and draw a freezing and thawing curve, such as Figure 2 and Figure 3 shown.

[0074] The juice loss rate and texture characteristics (hardness, cohesion, elasticity, adhesiveness, chewiness) of frozen and thawed shrimps were measured, and the muscle fiber structure of the two groups of shrimps was observed by electron microscopy. Figure 4 , Figure 5 and Figure 6 shown.

[0075] Freeze time: Figure 2 As shown in the data, under normal freezing conditions, the maximum ice crystal band formation time of shrimp is 119 min, and the freezing time is 197 min; under spatial high-voltage electrostatic field assisted freezing, the maximum ice crystal band formation time of shrimp is 36 min, and the freezing time is 111 min, which are shortened by 69.7% and 46.3% respectively.

[0076] Thawing time: Figure 3 As shown in the figure, the thawing time of shrimps frozen with ordinary conditions is 301 min under ordinary thawing conditions; while the thawing time of shrimps frozen with high-voltage electrostatic field assisted under contact high-voltage alternating electric field thawing conditions is 228 min, which is 24.3% shorter.

[0077] Juice loss rate after thawing: As shown in Table 1, compared with the shrimps that were normally frozen and thawed, the juice loss rate of the shrimps frozen with the aid of the AC / DC symbiotic electric field device after thawing with the aid of the high-voltage alternating electric field was reduced by 1.09%, indicating that the application of the AC / DC symbiotic electric field device to assist freezing and thawing can significantly reduce the outflow of juice from the shrimps after thawing.

[0078] Table 1. Juice loss rate of shrimp after thawing

[0079]

[0080] Texture: As shown in Table 2, compared with the ordinary frozen and thawed shrimps, the hardness, elasticity and chewiness of the shrimps assisted by the AC / DC symbiotic electric field device for freezing and thawing are significantly improved, indicating that the use of the AC / DC symbiotic electric field device to assist freezing and thawing can effectively improve the texture characteristics of shrimp meat and enhance the quality of shrimps after freezing and thawing.

[0081] Table 2. Texture of thawing shrimp

[0082]

[0083] Scanning electron microscope results: Figure 4 , Figure 5 , Figure 6 As shown in the figure, compared with the fresh samples, both freezing and thawing methods caused different degrees of damage to the muscle fiber structure of the shrimp. Under ordinary freezing and thawing conditions, the muscle fibers of the shrimp were severely broken, with large gaps and a large number of irregular cavities. However, the muscle fiber structure of the shrimp assisted by the AC / DC symbiotic electric field device was relatively complete, with smaller gaps and no obvious irregular cavities. This shows that the AC / DC symbiotic electric field device assisted freezing and thawing can effectively reduce the destructive effect of ice crystals on muscle fibers.

[0084] Although the embodiments and devices of the present invention have been disclosed above, they are not limited to the applications listed in the description and the embodiments. It can be fully applied to various fields suitable for the present invention. For those familiar with the art, additional modifications can be easily realized. Therefore, without departing from the general concept defined by the claims and equivalent scope, the present invention is not limited to the specific details and the illustrations shown and described here.

Claims

1. An AC / DC symbiotic electric field generating device, It is characterized in that The electric field generating device comprises an internal structure and an external structure; the internal structure comprises a solid-state high-voltage step-up transformer (1), a rectifier bridge (2), a safety resistor (3), and a coupling capacitor; The coupling capacitor comprises a coupling capacitor 1 (41) and a coupling capacitor 2 (42); the coupling capacitor 1 (41) is arranged between the solid-state high-voltage step-up transformer (1) and the rectifier bridge (2); the coupling capacitor 2 (42) is arranged between the solid-state high-voltage step-up transformer (1) and the safety resistor (3); The external structure includes a discharge electrode, an acrylic plate, and a metal storage plate (7); The internal structure of the electric field generating device is located outside the refrigerator and is connected to the discharge electrode through an insulated wire, and the external structure of the electric field generating device is located inside the refrigerator.

2. An AC / DC symbiotic electric field generating device as claimed in claim 1, Features: The solid-ratio high-voltage step-up transformer (1) is a 220 V to 5000 V solid-ratio step-up transformer with an operating frequency of 50-60 Hz. The rectifier bridge (2) can convert high-voltage alternating current into high-voltage direct current. The safety resistor (3) is internally composed of a high-resistance resistor and a leakage protector connected in series.

3. An AC / DC symbiotic electric field generating device as claimed in claim 1, Features: The discharge electrode comprises a discharge electrode 1 (51) and a discharge electrode 2 (52), which are respectively located at the top of the refrigerator freezing chamber (8) and the bottom of the thawing chamber (9); the acrylic plate comprises an acrylic plate 1 (61) and an acrylic plate 2 (62), which are respectively located below the metal storage plate (7) and above the discharge electrode 2 (52).

4. An AC / DC symbiotic electric field generating device as claimed in claim 3, Features: The discharge electrode is made of aluminum alloy and is insulated with acrylic plates at the top and bottom. A crossbeam and a partition bracket are installed on the side of the refrigerator freezer chamber (8) to adjust the distance between the discharge electrode 1 (51) and the metal storage plate (7). The metal storage plate (7) is an aluminum alloy plate connected to the ground through a wire, and the electric potential is always 0, so that a stable and uniform high-voltage electrostatic field is formed inside the freezer chamber (8). When the frozen food is placed above the metal storage plate (7), it has a certain spatial distance from the discharge electrode 1 (51), thereby avoiding leakage, enhancing the safety of use, and widening the scope of application.

5. An AC / DC symbiotic electric field generating device as claimed in claim 3, Features: A second acrylic plate (62) is installed above the second discharge electrode (52) at the bottom of the thawing chamber (9), and the food to be thawed is indirectly in contact with the second discharge electrode (52) through the second acrylic plate (62), forming a contact-type high-voltage alternating electric field, which effectively enhances the destructive effect of the electric field force on ice crystals and prevents the food from directly contacting the discharge electrode to cause electric shock.

6. The AC / DC symbiotic electric field generating device according to claim 1, Features: The electric field generating device can generate high-voltage direct current and high-voltage alternating current simultaneously; the 220 V mains power is boosted to a high-voltage 5000 V alternating current by a booster (1), converted to a high-voltage direct current by a rectifier bridge (2), and then output to the first discharge electrode (51) through a safety resistor (3) to form a high-voltage electrostatic field; the 220 V mains power is boosted to a high-voltage 5000 V alternating current by a booster (1), and directly output to the second discharge electrode (52) through a safety resistor (3) to form a high-voltage alternating electric field; the coupling capacitor provides direct current filtering and overvoltage protection.

7. An AC / DC symbiotic electric field generating device as claimed in claim 6, Features: The distance between the spatial high-voltage electrostatic field discharge electrode 1 (51) and the metal storage plate (7) is adjustable, so that a uniform electric field is formed in the space.

8. An AC / DC symbiotic electric field generating device as claimed in claim 6, Features: High-voltage direct current is output to the first discharge electrode (51) at the top of the refrigerator freezing chamber (8), forming a spatial high-voltage electrostatic field; high-voltage alternating current is output to the second discharge electrode (52) at the bottom of the thawing chamber (9), forming a contact-type high-voltage alternating electric field.

9. An AC / DC symbiotic electric field generating device as claimed in claim 8, Features: The electric field generating device can output high-voltage direct current and high-voltage alternating current to the discharge electrode at the same time, and simultaneously form a spatial high-voltage electrostatic field and a contact-type high-voltage alternating electric field.

10. Application of the AC / DC symbiotic electric field generating device according to any one of claims 1 to 9 in freezing and thawing of food, Features: The method of using a spatial high-voltage electrostatic field to assist in freezing food includes the following steps: S1. Apply fluidized ice on the surface of fresh aquatic products, place them in a freezing chamber equipped with a spatial high-voltage electrostatic field device, adjust the voltage to 0.5-1.5KV, adjust the temperature to -2~-5℃, and the processing time is 1-3h; S2, adjusting the electric field voltage of step S1 to 4.0-5 KV, the temperature to -16--18°C, and the processing time to 20-40 min; S3, adjusting the electric field voltage of step S1 to 1.0-3KV, adjusting the temperature to -2--5°C, and the processing time to 1-2h.

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