Magnetic field preservation control method based on electromagnetic field assistance

Abstract

The invention relates to the technical field of food processing, and discloses a magnetic field fresh-keeping control method based on electromagnetic field assistance, which comprises the following steps: step 1, cleaning and peeling: cleaning fruit raw materials, removing impurities such as silt, draining, and peeling and denucleating; the raw materials obtained in the first step pass through a radio frequency processing cavity, the radio frequency power is 70-80%, and the radio frequency time is 90-120 s. And step 3, cutting and packaging: cutting the raw materials obtained in the step 2, and putting the cut raw materials into a plastic box or a packaging bag for sealing and packaging. And 4, magnetic field storage: putting the fresh-cut fruits obtained in the step 3 into a magnetic field incubator, and carrying out fresh-keeping treatment in a static magnetic field mode at the magnetic field intensity of 3-5mT and the temperature of 2-4 DEG C. The dual-mode technical scheme of radio frequency pretreatment combined with static magnetic field storage is adopted, dual regulation and control of enzyme activity inhibition and microorganism inactivation are achieved, and spoilage microorganisms are controlled within a safety threshold value while the natural color and luster of fruits and vegetables are kept.

Description

Technical Field

[0001] The present invention relates to the technical field of food processing, and specifically relates to a magnetic field fresh-keeping control method based on electromagnetic field assistance. Background Art

[0002] Fresh-cut fruits, also known as lightly processed fruits or sliced fruits, are ready-to-eat products obtained by subjecting fresh fruits to processes such as grading, washing, disinfection, draining, peeling (pitting), slicing, color protection, and packaging for consumers to eat. Due to their advantages such as high quality and freshness, convenience in consumption, and high edible rate, they have gradually gained the favor of consumers.

[0003] However, the processing of fresh-cut fruits is different from traditional food processing and has relatively high technical requirements. Compared with ordinary fruits, fresh-cut fruits have a shorter shelf life, and a series of physiological and biochemical reactions and quality changes will occur during the processes of operation, storage, transportation, and sales. Fresh-cut processing involves cutting the tissues of fresh agricultural products, resulting in damage to the main tissues and the release of tissue-related substances, which destroys the original protection system and accelerates the aging process and aggravates the decay of fruits and vegetables, and other quality deterioration phenomena. At present, the research on the fresh-keeping of fresh-cut fruits is increasing day by day, and relatively common fresh-keeping technologies include coating technology, modified atmosphere packaging, radiation treatment, etc. Summary of the Invention

[0004] Aiming at the deficiencies of the prior art, the present invention provides a magnetic field fresh-keeping control method based on electromagnetic field assistance, which solves the technical defect problem that it is difficult to balance color protection and sterilization when traditional radiation or magnetic field acts alone.

[0005] To achieve the above objectives, the present invention is realized through the following technical solutions: A magnetic field fresh-keeping control method based on electromagnetic field assistance, comprising the following steps:

[0006] Step 1, cleaning and peeling: cleaning the fruit raw materials, removing impurities such as sediment, and draining and then peeling and pitting;

[0007] Step 2, radio frequency treatment: passing the raw materials obtained in Step 1 through a radio frequency treatment chamber;

[0008] Step 3, slicing and packaging: slicing the raw materials obtained in Step 2 and putting them into a plastic box or a packaging bag for sealed packaging;

[0009] Step 4, magnetic field storage: putting the fresh-cut fruits obtained in Step 3 into a magnetic field incubator and performing fresh-keeping treatment in a static magnetic field mode, with a magnetic field intensity of 3 - 5 mT and a temperature of 2 - 4 °C.

[0010] Furthermore, the spatial structure of oxidase in pulp cells is directionally damaged through radio frequency pretreatment, and the activity of key enzymes in microbial metabolism is inhibited by static magnetic fields, forming a time-sequential action chain of physical fields; washing and peeling reduce the initial microbial load, and sealed packaging blocks external pollution sources, realizing the whole-process collaborative preservation from raw material processing to storage, and breaking through the technical contradiction that it is difficult to synchronously optimize color protection and antibacterial in traditional preservation technologies.

[0011] Preferably, the power of the radio frequency treatment is 70 - 80%, the treatment time is 90 - 120 s, and the electrode spacing of the radio frequency treatment chamber is 10 - 15 cm.

[0012] Furthermore, the power threshold is dynamically matched based on the pulp dielectric constant and loss factor to ensure the effective conversion of electromagnetic energy into molecular kinetic energy to damage the enzyme active center, while avoiding excessive heating that causes the cell sap to boil; the electrode spacing regulates the uniformity of the electric field distribution, prevents the formation of standing wave reflection of high-frequency electromagnetic waves on the pulp surface, reduces energy loss and improves the processing efficiency.

[0013] Preferably, the static magnetic field mode adopts a bipolar pulsed magnetic field, the pulse frequency is 10 - 50 Hz, and the magnetic field intensity gradient is controlled within the range of ±0.2 mT.

[0014] Furthermore, the bipolar pulse disturbs the charge distribution of the lipid layer of the microbial cell membrane by periodically reversing the magnetic field direction, resulting in membrane potential imbalance; the pulse frequency avoids the inherent frequency (50 - 100 Hz) of the opening and closing of the cell membrane ion channel to avoid non-selective cell damage caused by resonance; the magnetic field gradient limit ensures the uniform distribution of the Lorentz force on the cell membrane surface and prevents membrane rupture caused by local stress concentration.

[0015] Preferably, the sealed packaging is modified atmosphere packaging, and the oxygen concentration in the package is maintained at 3 - 5%, and the carbon dioxide concentration is adjusted to 8 - 12%.

[0016] Furthermore, the low-oxygen environment inhibits the oxygen-dependent catalytic activity of polyphenol oxidase, and the increase in carbon dioxide concentration reduces the activity of succinate dehydrogenase in mitochondria, forming a triple blockage of the metabolic pathway with the inhibitory effect of the magnetic field on the cell membrane ATPase; the gas component ratio is set according to the respiratory quotient curve of fruits and vegetables to achieve the dynamic balance of the respiratory rate and physical field intervention.

[0017] Preferably, the size of the cut fruit blocks after cutting is 2 - 3 cm³, and the surface of the cutting tool is coated with a nano-silver antibacterial coating.

[0018] Furthermore, cube cutting reduces the surface area to volume ratio of the pulp exposure, reducing the enzymatic browning rate caused by oxygen contact; the nano-silver coating binds to the thiol groups on the microbial cell wall through the slow release of Ag + to disrupt the transmembrane proton gradient and block the cross-contamination of microorganisms on the surface of the cutting tool during the cutting process.

[0019] Preferably, the magnetic field incubator is internally provided with a superconducting magnet array, the magnetic field uniformity error ≤ 5%, and the temperature fluctuation range is ±0.5 °C.

[0020] Furthermore, the superconducting magnet eliminates the Joule heat effect of the traditional electromagnetic coil, avoiding the interference of extra heat on the storage temperature stability; the magnetic field uniformity ensures the dynamic balance of the osmotic pressure inside and outside the cells, preventing the local weak magnetic field area from becoming the breakthrough point of microbial reproduction; the precise temperature control inhibits the phase change of the pulp cell membrane at low temperature and maintains the integrity of the semi-permeable membrane function of the cell wall.

[0021] Preferably, a pre-cooling step is added before the radio frequency treatment in step 2, and the raw material is cooled to 5 - 8 °C and maintained for 10 - 15 min.

[0022] Furthermore, pre-cooling reduces the initial temperature of the pulp below the inflection point of the dielectric loss, reducing the heat generation caused by the dipole rotation of polar molecules (such as water) during radio frequency treatment; the low temperature maintenance time ensures that the central temperature of the pulp drops evenly, avoiding the thermal stress damage of the cell membrane caused by the temperature difference between the surface and the inside.

[0023] Preferably, weak ultraviolet irradiation is synchronously applied during the magnetic field storage stage, with a wavelength of 365 nm and an irradiation intensity of 0.5 - 1.0 W / m 2 。

[0024] Furthermore, ultraviolet light blocks the replication process by inducing the cross-linking between DNA strands of microorganisms, forming a synergistic lethal effect with the magnetic field that inhibits the activity of DNA repair enzymes; the specific wavelength excites the titanium dioxide nanomaterial on the inner wall of the package to generate hydroxyl radicals, decomposing ethylene and volatile spoilage products, and constructing a dynamic gas purification system.

[0025] Preferably, after cleaning and peeling in step 1, color protection treatment is carried out with a 0.1 - 0.3% ascorbic acid solution, and the soaking time is 2 - 3 min.

[0026] Furthermore, ascorbic acid competitively binds to the copper ion site at the active center of polyphenol oxidase, blocking the conversion of catechol to quinone substances; the acidic environment (pH 3 - 4) inhibits the activity of pectin methyl esterase, reducing the degradation of pectin in the middle lamella between cells and maintaining the mechanical strength of the pulp tissue.

[0027] Preferably, the inner wall of the plastic box is compounded with an activated carbon - titanium dioxide nanomembrane, and the membrane thickness is 50 - 80 nm.

[0028] Furthermore, the three-dimensional pore structure of the activated carbon selectively adsorbs ripening gases such as ethylene and α-farnesene, and the titanium dioxide nanocrystals generate reactive oxygen species under ultraviolet excitation to decompose lipid peroxides; the nanoscale thickness balances the gas adsorption capacity and the photocatalytic reaction rate, forming a self-cleaning packaging internal environment.

[0029] The present invention provides a magnetic field preservation control method based on electromagnetic field assistance. It has the following beneficial effects:

[0030] 1. The present invention adopts a dual-mode technical solution of radio frequency pretreatment combined with static magnetic field storage to achieve dual regulation of enzyme activity inhibition and microbial inactivation. Compared with the existing single physical field preservation technology, it breaks through the contradiction between thermal effect damage and low antibacterial efficiency, while maintaining the natural color of fruits and vegetables, it controls the spoilage microorganisms within the safety threshold, and solves the technical defect that it is difficult to balance color protection and sterilization when traditional radiation or magnetic field acts alone.

[0031] 2. The present invention forms the optimal ratio of thermal effect and non-thermal effect by constraining the power threshold and time window of radio frequency treatment. Compared with the conventional high-intensity radio frequency solution, it completely inactivates the oxidase while avoiding overheating of the pulp tissue, eliminating the problems of texture softening and non-enzymatic browning caused by temperature runaway, and overcoming the industry problem of mutual restriction between sterilization and quality maintenance in the prior art.

[0032] 3. The present invention designs a 3-5mT magnetic field intensity action range to synchronously regulate cell membrane permeability and microbial metabolic activity. Compared with the traditional weak magnetic field preservation method, it produces an order of magnitude improvement in inhibiting water loss and respiration, and solves the problem of quality deterioration during storage, such as decreased hardness and high weight loss rate caused by insufficient intervention of low-intensity magnetic fields on the physiological activities of fruits and vegetables.

[0033] 4. The present invention constructs a triple protection system of radio frequency inactivation, sealed oxygen inhibition, and magnetic field control. Compared with single modified atmosphere packaging or low-temperature storage solutions, the risk of secondary microbial contamination is reduced through the synergistic effect of the physical field, blocking the browning chain reaction, so that fresh-cut fruits can maintain commercial-grade appearance and nutritional integrity during the 7-day storage period, subverting the inherent perception that shelf life and edible quality cannot be achieved at the same time with traditional preservation technology. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 This is a diagram showing the influence of different radio frequency conditions on the L* value and the total number of bacterial colonies of the present invention;

[0035] Figure 2 The present invention is a flow chart of the method. DETAILED DESCRIPTION

[0036] The following will be combined with the drawings in the specification of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0037] Please see attached Figure 1 -Attached Figure 2 :

[0038] Example 1 Optimization of Radio Frequency Parameters

[0039] As Figure 1 can be seen, radio frequency treatment can inactivate the PPO activity in fruits, prevent oxidative browning. At the same time, due to the thermal and non-thermal effects of radio frequency, the total colony count of fresh-cut fruits is also significantly reduced. With the increase of radio frequency power and the extension of treatment time, the enzyme activity and microorganisms are effectively controlled. When the radio frequency power is 70-90% and the time is 90-120 s, the color and microorganism control of fresh-cut fruits are better. When the radio frequency intensity exceeds 90%, although the microorganisms have been reduced to less than 10 cfu / mL, due to the strong thermal effect on the fruits, serious non-enzymatic browning occurs and the fruit color darkens.

[0040] Example 2 Optimization of Magnetic Field Parameters

[0041] The application of magnetic field in fruit preservation is based on its regulatory effect on the internal substances of fruits. By generating a low-temperature environment, the magnetic field can inhibit the growth of microorganisms in fruits and delay the senescence process of fruits. As can be seen from Table 1, the changes in the quality indicators of fresh-cut fruits under different magnetic field intensities are significantly different. When the magnetic field intensity is small, the magnetic field effect cannot affect cells and microorganisms, resulting in significant increases in water loss, hardness and weight loss rate of fresh-cut fruits, and an increase in the current situation of the total colony count. When the magnetic field intensity is greater than 3 mT, the magnetic field can effectively inhibit cell water loss and microbial reproduction, and improve the storage quality of fresh-cut fruits.

[0042] Table 1 Index differences after treatment with different magnetic field intensities for 7 days

[0043] Magnetic field strength / mT Hardness / N Weight loss rate / % Total number of colonies (CFU / mL) 0 110±1.24 1.76±0.01 220±2.91 1 138±2.91 1.83±0.01 175±3.05 2 161±1.88 1.17±0.01 139±5.42 3 265±3.12 0.35±0.01 37±4.13 4 243±1.36 0.39±0.01 29±3.28 5 254±1.09 0.34±0.01 18±1.10

[0044] Example 1

[0045] A method for improving the preservation effect of fresh-cut fruits by using electromagnetic field-assisted technology, comprising the following steps:

[0046] (1) Cleaning and peeling: Cleaning the fruit raw materials, removing impurities such as sediment, draining, and then peeling and removing the cores.

[0047] (2) Radio frequency treatment: Passing the raw materials obtained in step (1) through a radio frequency treatment chamber, with a radio frequency power of 70% and a radio frequency time of 90 s.

[0048] (3) Slicing and packaging: Slicing the raw materials obtained in step (2) and putting them into a plastic box or packaging bag for sealed packaging.

[0049] (4) Magnetic field storage: Putting the fresh-cut fruits obtained in step (3) into a magnetic field incubator and performing preservation treatment in a static magnetic field mode, with a magnetic field intensity of 5 mT and a temperature of 4°C.

[0050] Example 2

[0051] A method for improving the fresh - cut fruit preservation effect by using electromagnetic field - assisted technology, comprising the following steps:

[0052] (1) Cleaning and peeling: Cleaning the fruit raw materials, removing impurities such as sediment, draining, and then peeling and removing the cores.

[0053] (2) Radio - frequency treatment: Passing the raw materials obtained in step (1) through a radio - frequency treatment chamber, with a radio - frequency power of 80% and a radio - frequency time of 120 s.

[0054] (3) Slicing and packaging: Slicing the raw materials obtained in step (2) and putting them into a plastic box or a packaging bag for sealed packaging.

[0055] (4) Magnetic field storage: Putting the fresh - cut fruits obtained in step (3) into a magnetic field incubator and performing preservation treatment in a static magnetic field mode, with a magnetic field intensity of 3 mT and a temperature of 2 °C.

[0056] Example 3

[0057] A method for improving the fresh - cut fruit preservation effect by using electromagnetic field - assisted technology, comprising the following steps:

[0058] (1) Cleaning and peeling: Cleaning the fruit raw materials, removing impurities such as sediment, draining, and then peeling and removing the cores.

[0059] (2) Radio - frequency treatment: Passing the raw materials obtained in step (1) through a radio - frequency treatment chamber, with a radio - frequency power of 75% and a radio - frequency time of 100 s.

[0060] (3) Slicing and packaging: Slicing the raw materials obtained in step (2) and putting them into a plastic box or a packaging bag for sealed packaging.

[0061] (4) Magnetic field storage: Putting the fresh - cut fruits obtained in step (3) into a magnetic field incubator and performing preservation treatment in a static magnetic field mode, with a magnetic field intensity of 5 mT and a temperature of 2 °C.

[0062] Example 4

[0063] A method for improving the fresh - cut fruit preservation effect by using electromagnetic field - assisted technology, comprising the following steps:

[0064] (1) Cleaning and peeling: Cleaning the fruit raw materials, removing impurities such as sediment, draining, and then peeling and removing the cores.

[0065] (2) Radio - frequency treatment: Passing the raw materials obtained in step (1) through a radio - frequency treatment chamber, with a radio - frequency power of 70% and a radio - frequency time of 120 s.

[0066] (3) Slicing and packaging: Slicing the raw materials obtained in step (2) and putting them into a plastic box or a packaging bag for sealed packaging.

[0067] (4) Magnetic field storage: Put the fresh-cut fruits obtained in step (3) into a magnetic field incubator and perform preservation treatment in the static magnetic field mode, with a magnetic field intensity of 4 mT and a temperature of 3 °C.

[0068] Comparative Example 1

[0069] Different from Example 1, radio frequency treatment was not used, and the remaining steps were the same as those in Example 1, specifically as follows:

[0070] (1) Cleaning and peeling: Wash the fruit raw materials, remove impurities such as sediment, and drain and then peel and pit them.

[0071] (2) Slicing and packaging: Cut the raw materials obtained in step (2) and put them into a plastic box or packaging bag for sealed packaging.

[0072] (3) Magnetic field storage: Put the fresh-cut fruits obtained in step (3) into a magnetic field incubator and perform preservation treatment in the static magnetic field mode, with a magnetic field intensity of 4 mT and a temperature of 4 °C.

[0073] Comparative Example 2

[0074] Different from Example 1, magnetic field treatment was not used, and the remaining steps were the same as those in Example 1, specifically as follows:

[0075] (1) Cleaning and peeling: Wash the fruit raw materials, remove impurities such as sediment, and drain and then peel and pit them.

[0076] (2) Radio frequency treatment: Pass the raw materials obtained in step (1) through a radio frequency treatment chamber, with a radio frequency power of 70% and a radio frequency time of 120 s.

[0077] (3) Slicing and packaging: Cut the raw materials obtained in step (2) and put them into a plastic box or packaging bag for sealed packaging.

[0078] (4) Low-temperature storage: Put the fresh-cut fruits obtained in step (3) into a 4 °C refrigerator.

[0079] Comparative Example 3

[0080] The radio frequency treatment conditions are different from those in Example 1, and the remaining steps are the same as those in Example 1, specifically as follows:

[0081] (1) Cleaning and peeling: Wash the fruit raw materials, remove impurities such as sediment, and drain and then peel and pit them.

[0082] (2) Radio frequency treatment: Pass the raw materials obtained in step (1) through a radio frequency treatment chamber, with a radio frequency power of 90% and a radio frequency time of 200 s.

[0083] (3) Slicing and packaging: Cut the raw materials obtained in step (2) and put them into a plastic box or packaging bag for sealed packaging.

[0084] (4) Magnetic field storage: Put the fresh-cut fruits obtained in step (3) into a magnetic field incubator and perform preservation treatment in a static magnetic field mode, with a magnetic field intensity of 3 mT and a temperature of 2 °C.

[0085] Comparative Example 4

[0086] The radio frequency treatment conditions are different from those in Example 1, and the remaining steps are the same as those in Example 1, specifically as follows:

[0087] (1) Cleaning and peeling: Wash the fruit raw materials, remove impurities such as sediment, and drain and then peel and pit them.

[0088] (2) Radio frequency treatment: Pass the raw materials obtained in step (1) through the radio frequency treatment chamber, with a radio frequency power of 50% and a radio frequency time of 60 s.

[0089] (3) Slicing and packaging: Cut and process the raw materials obtained in step (2) and put them into a plastic box or packaging bag for sealed packaging.

[0090] (4) Magnetic field storage: Put the fresh-cut fruits obtained in step (3) into a magnetic field incubator and perform preservation treatment in a static magnetic field mode, with a magnetic field intensity of 3 mT and a temperature of 2 °C.

[0091] Comparative Example 5

[0092] The magnetic field treatment conditions are different from those in Example 1, and the remaining steps are the same as those in Example 1, specifically as follows:

[0093] (1) Cleaning and peeling: Wash the fruit raw materials, remove impurities such as sediment, and drain and then peel and pit them.

[0094] (2) Radio frequency treatment: Pass the raw materials obtained in step (1) through the radio frequency treatment chamber, with a radio frequency power of 70% and a radio frequency time of 90 s.

[0095] (3) Slicing and packaging: Cut and process the raw materials obtained in step (2) and put them into a plastic box or packaging bag for sealed packaging.

[0096] (4) Magnetic field storage: Put the fresh-cut fruits obtained in step (3) into a magnetic field incubator and perform preservation treatment in a static magnetic field mode, with a magnetic field intensity of 1 mT and a temperature of 4 °C.

[0097] Table 2 Comparison of the effects of Examples and Comparative Examples after 7 days of storage

[0098]

[0099]

[0100] It can be seen from the data comparison in Table 1 above that the quality indicators of fresh-cut fruits produced by different processing technologies are significantly different. In Comparative Example 1, radio frequency treatment was not adopted, resulting in browning during cutting, which had an adverse effect on the color of the later product. In Comparative Example 2, magnetic field storage was not adopted, and the respiration of the fruit was not well inhibited, and at the same time, the growth of microorganisms could not be inhibited. As a result, the weight loss rate and hardness loss of the fresh-cut fruit pieces were relatively large. In Comparative Examples 3 and 4, the radio frequency intensity was too large and too small respectively. A large radio frequency intensity led to serious heating of the fruit pieces and a large water loss rate, and too small radio frequency intensity could not achieve the effects of enzyme inactivation and bacteria reduction. In Comparative Example 5, the magnetic field intensity was too small to well inhibit the respiration during storage and the reproduction of microorganisms.

[0101] Although the embodiments of the present invention have been shown and described, for those of ordinary skill in the art, it can be understood that various changes, modifications, substitutions, and variations can be made to these embodiments without departing from the principle and spirit of the present invention. The scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A magnetic field preservation control method based on electromagnetic field assistance, characterized in that, It includes the following steps: Step 1, cleaning and peeling: Clean the fruit raw materials, remove impurities such as sediment, drain, and then peel and pit them; Step 2, radio frequency treatment: Pass the raw materials obtained in Step 1 through the radio frequency treatment chamber; Step 3, cutting and packaging: Cut and process the raw materials obtained in Step 2, and put them into plastic boxes or packaging bags for sealed packaging; Step 4, magnetic field storage: Put the fresh-cut fruits obtained in Step 3 into a magnetic field incubator, and carry out preservation treatment in the static magnetic field mode, with a magnetic field strength of 3 - 5 mT and a temperature of 2 - 4 °C.

2. The magnetic field freshness preservation control method based on electromagnetic field assistance according to claim 1, wherein, The power of the radio frequency treatment is 70 - 80%, the treatment time is 90 - 120 s, and the electrode spacing of the radio frequency treatment chamber is 10 - 15 cm.

3. A magnetic field preservation control method based on electromagnetic field assistance according to claim 1, characterized in that, The static magnetic field mode adopts a bipolar pulsed magnetic field, with a pulse frequency of 10 - 50 Hz, and the magnetic field strength gradient is controlled within the range of ±0.2 mT.

4. A magnetic field preservation control method based on electromagnetic field assistance according to claim 1, characterized in that, The sealed packaging is a modified atmosphere packaging, with the oxygen concentration in the package maintained at 3 - 5% and the carbon dioxide concentration adjusted to 8 - 12%.

5. A magnetic field preservation control method based on electromagnetic field assistance according to claim 1, characterized in that The size of the fruit pieces after the slicing process is 2-3 cm 3 , and the surface of the slicing tool is coated with a nano-silver antibacterial coating.

6. A magnetic field freshness preservation control method based on electromagnetic field assistance according to claim 1, characterized in that The magnetic field incubator is internally provided with a superconducting magnet array, with a magnetic field uniformity error ≤5% and a temperature fluctuation range of ±0.5 °C.

7. A magnetic field preservation control method based on electromagnetic field assistance according to claim 1, characterized in that, Before the radio frequency treatment in Step 2, add a pre-cooling step to cool the raw materials to 5 - 8 °C and maintain for 10 - 15 min.

8. A magnetic field preservation control method based on electromagnetic field assistance according to claim 1, characterized in that During the magnetic field storage stage, weak ultraviolet irradiation with a wavelength of 365 nm and an irradiation intensity of 0.5 - 1.0 W / m is applied synchronously. 2 .

9. A magnetic field preservation control method based on electromagnetic field assistance according to claim 1, characterized in that, After cleaning and peeling in Step 1, carry out color protection treatment with a 0.1 - 0.3% ascorbic acid solution, and the soaking time is 2 - 3 min.

10. A magnetic field preservation control method based on electromagnetic field assistance according to claim 1, characterized in that, The inner wall of the plastic box is compounded with an activated carbon - titanium dioxide nanomembrane, and the membrane thickness is 50 - 80 nm.

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