Magnetic control fresh-keeping method and system for pork
By installing Helmholtz coils and temperature and humidity sensors inside the pork preservation chamber, the magnetic field parameters can be adjusted in real time, solving the problems of high energy consumption and risks associated with chemical preservatives in pork preservation, and achieving efficient and safe magnetic control preservation.
Patent Information
- Application Number
- CN202511174329.4
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-08-21
- Publication Date
- 2025-11-25
AI Technical Summary
Existing methods for preserving pork are energy-intensive, costly, and pose potential health risks due to chemical preservatives. They also lack sufficient effectiveness in inhibiting microorganisms and delaying oxidation, resulting in a short shelf life.
The magnetic control preservation method is adopted. By installing Helmholtz coils in the preservation chamber, combined with temperature and humidity sensors and air cooling devices, the magnetic field strength, frequency and time are adjusted in real time to inhibit the growth of microorganisms and delay the oxidation reaction, thus avoiding the use of chemical preservatives.
It significantly extends the shelf life of pork, reduces energy consumption, ensures food safety, avoids the use of chemical preservatives, and achieves a highly efficient preservation effect.
Smart Images
Figure CN121003237A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of food preservation technology, and in particular to a magnetic control preservation method and system for pork. Background Technology
[0002] Currently, the preservation of pork in meat processing, storage, and cold chain transportation mainly relies on methods such as low-temperature refrigeration, vacuum packaging, and the addition of chemical preservatives. Low-temperature refrigeration requires continuous energy consumption and has high equipment costs; although vacuum packaging can inhibit microbial growth, the packaging materials are expensive and may affect the taste of the meat; chemical preservatives pose potential health risks and have low consumer acceptance; the above methods are not effective enough in inhibiting microorganisms and delaying oxidation, resulting in a short shelf life for pork.
[0003] Therefore, there is an urgent need for a magnetic preservation method and system that reduces energy consumption and cost of pork preservation, avoids the use of chemical preservatives to ensure food safety, effectively inhibits microbial growth and delays oxidation reactions, and significantly extends the shelf life of pork. Summary of the Invention
[0004] To address the shortcomings of existing technologies, this invention provides a magnetically controlled preservation method and system for pork.
[0005] The present invention adopts the following technical solution: A magnetic preservation method for pork includes the following steps: S1: Preparation of the magnetic field device for the cold storage: Helmholtz coils are coaxially distributed on the outside of the preservation chamber wall, and the distance between the two coils is sufficient to ensure that the magnetic field uniformly covers the pork pieces of the preset weight. A wind-cooling device is installed at the top opening of the preservation chamber, and the magnetic field is adjusted to ensure that the magnetic induction intensity in the central processing area is uniform and meets the preset requirements. The refrigeration compartment is equipped with a temperature and humidity sensor, and is spaced at a preset distance from the pork pieces placed on the central processing area. S2: Set magnetic field control parameters: The magnetic field action time, magnetic field action mode, magnetic field strength, and frequency are set according to the quality and preservation time of the pork chunks. The magnetic field action time includes a pre-target time period, which is the set time period during which the magnetic field begins to continuously act on the pork chunks. S3: Preservation magnetic field control and monitoring: According to the preset magnetic field action mode and parameters, the control coil generates a constant or alternating magnetic field to control the operation of the air-cooling device. It also acquires the temperature and humidity information transmitted by the temperature and humidity sensor in the preservation chamber in real time. If the temperature or humidity exceeds the preset range, it automatically adjusts the frequency for protection. S4: Timed detection of pork chunks: After the magnetic field continues to act on the target time period, the physicochemical indicators TBARs value, TVB-N value, pH value, water content and L*, a*, b* color sensory indicators of the pork chunks are detected, the measured values are obtained and compared with the preset qualified values; S5: Based on the test results, determine whether the magnetic field parameters need to be adjusted. When the physical and chemical indicators fail to meet the requirements, the current of the electromagnetic coil and the continuous / intermittent power supply mode are automatically adjusted until the test is passed. S6: Perform the preservation process: A magnetic field is applied periodically according to a preset program within the preservation period, and the operation is dynamically controlled by feedback from temperature and humidity sensors.
[0006] In some embodiments, in S1, at least one pair of sensor modules are provided, symmetrically located on both sides of the pork block, and are in a non-contact state with the pork block placed in the central processing area.
[0007] In some embodiments, in S1, adjusting the magnetic field to make the uniformity error of the magnetic induction intensity in the central processing area meet a preset requirement includes: controlling the magnetic field intensity by using an external adjustable DC power supply or a low-frequency alternating power supply to meet the preservation requirements of the pork chunks, and the uniformity error of the magnetic induction intensity in the central processing area ΔB ≤ ±5%, calculated according to formula (1): ΔB=(B max -B min ) / B avg ×100% (1) In the formula, B max This represents the maximum magnetic field strength inside the cold storage compartment, expressed in tons (T). B min This represents the minimum magnetic field strength inside the cold storage compartment, expressed in tons (T). B avg The average magnetic field strength is expressed in tons (T).
[0008] In some embodiments, in S2, the magnetic field action mode includes a constant magnetic field and a phased-controlled intermittent magnetic field mode. The target time period is set to 30-60 minutes.
[0009] In some embodiments, in S3, the preset temperature range is -3.5 to 4°C, and the coil temperature rise is ≤15°C, and the humidity range is 80 to 95% RH.
[0010] In some embodiments, in S4, the physicochemical properties should meet the following requirements: TBARs less than 0.5 mg MDA / kg, total volatile basic nitrogen (TVB-N) less than 15 mg / 100g; pH not greater than 6.2; water loss not greater than 5%; no abnormal color change, of which L* value is between 35 and 53, a* value not exceeding 15, and b* value not exceeding 10. The TBARs value is calculated according to formula (2): TBARs =(A532-A600) / m×9.48 (2) In the formula: TBARs are thiobarbituric acid reactants, with units of mg MDA / kg; A532 is the absorbance of the sample at a wavelength of 532 nm, expressed in L / (g·cm). A600 is the absorbance of the sample at a wavelength of 600 nm, with background correction, and the unit is L / (g·cm). M represents the sample mass, in grams. 9.48 is the molar absorptivity, unit: L·mol⁻¹ -1 ·cm -1 .
[0011] In some embodiments, in S5, when the physical and chemical indicators are not up to standard, the current magnitude and continuous / intermittent power supply mode of the electromagnetic coil are automatically adjusted, including: according to the different physical and chemical indicators that exceed the standard, one or more of the following are selected: magnetic field strength, frequency, number of daily treatments, single magnetic field action time, humidity, constant magnetic field mode and intermittent magnetic field mode.
[0012] In some embodiments, in S6, a magnetic field is periodically applied according to a preset program within the preservation time, and dynamic control is performed through feedback from a temperature and humidity sensor. This includes: dynamically adjusting the cycle and parameters based on real-time monitoring results from the temperature and humidity sensor, performing the operation through program preset and closed-loop feedback, while simultaneously coordinating the adjustment of the air-cooling device, and ensuring that the overall power consumption meets the preset requirements.
[0013] This invention also discloses a magnetically controlled preservation system for pork, and a method for implementing magnetically controlled preservation of pork, comprising a support frame, a preservation chamber installed in the middle of the support frame, and two Helmholtz coils symmetrically installed on the upper and lower outer walls of the preservation chamber; the preservation chamber has an internal space in the middle, a top opening at the top, side through holes on the side walls, and a bottom through hole at the bottom; a cooling device is installed at the top opening, and a horizontal placement platform for placing the pork piece to be tested is provided in the bottom through hole, and the vertical center line of the horizontal placement platform coincides with the center lines of the two coils.
[0014] In some embodiments, the preservation compartment is further provided with an electrically connected temperature and humidity sensor and a main control unit; there are two temperature and humidity sensors, symmetrically located on both sides of the pork block, and the distance H between them and the pork block should satisfy: 1.7cm≤H≤2.3cm.
[0015] The main control unit is also electrically connected to the coil and the air-cooling device. The main control unit is equipped with a power supply module, a current regulation module, and a microcontroller. The microcontroller includes a memory, a processor, and a computer program stored in the memory and capable of running on the processor to control the temperature and humidity sensor, the coil, and the air-cooling device to execute commands.
[0016] It should be noted that the preferred value for H is 2cm.
[0017] Beneficial effects:
[0018] This invention discloses a magnetically controlled preservation method and system for pork, which has the following advantages compared with the prior art: This invention discloses a magnetic control preservation method and system for pork. It utilizes Helmholtz coils symmetrically installed on the upper and lower outer walls of a preservation chamber. The spacing between the two coils ensures uniform magnetic field coverage of a preset weight of pork pieces. Furthermore, the uniformity error of the magnetic induction intensity at the horizontal placement platform in the center of the pork pieces is ≤±5%, ensuring uniform magnetization of the pork pieces. A cooling device is installed at the top opening of the preservation chamber to assist in cooling. Temperature and humidity sensors placed inside the chamber are kept in a non-contact state with the pork pieces to prevent contamination and condensation interference, ensuring the accuracy of the detection data. The magnetic field application time, mode, intensity, and frequency are set according to the weight of the pork pieces and the preservation time. The temperature and humidity sensors, coils, and cooling device are all connected to a control unit. The control unit adjusts the magnetic field for preservation based on real-time temperature and humidity data and an internal program, achieving high-precision control. The use of a high-efficiency inverter and low-loss coils significantly reduces overall power consumption. The magnetic field control technology effectively inhibits microbial growth and delays oxidation, significantly extending the pork's shelf life. This preservation method not only significantly extends the pork's shelf life but also avoids the use of chemical preservatives, ensuring food safety. Attached Figure Description
[0019] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below, which constitute a part of the present invention. The illustrative embodiments of the present invention and their descriptions explain the present invention and do not constitute an improper limitation of the present invention. Figure 1 A flowchart of a magnetic preservation method for pork provided in an embodiment of the present invention; Figure 2A schematic diagram of the structure of the magnetically controlled preservation system for pork provided in an embodiment of the present invention; Figure 3 for Figure 2 AA section view; Figure 4 This is a block diagram of the main control unit.
[0020] In the diagram: 1. Support frame; 2. Magnetic field generator; 21. Coil; 3. Fresh-keeping compartment; 31. Internal space; 32. Top opening; 33. Side through hole; 34. Bottom through hole; 4. Horizontal placement platform; 5. Main control unit; 51. Power module; 52. Current regulation module; 53. Microcontroller; 531. Memory; 532. Processor; 6. Wire; 7. Temperature and humidity sensor; 8. Cooling fan; 9. Pork chunks. Detailed Implementation
[0021] The following description, in conjunction with the accompanying drawings, illustrates exemplary embodiments of the present invention, including various details to aid understanding. These details should be considered merely exemplary. Therefore, those skilled in the art will recognize that various changes and modifications can be made to the embodiments described herein without departing from the scope and spirit of the invention. Similarly, for clarity and brevity, descriptions of well-known functions and structures are omitted in the following description.
[0022] In the description of this invention, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.
[0023] like Figures 1-4 As shown, the technical solution of the present invention is as follows: A magnetic preservation method for pork includes the following steps: S1: Preparation of the magnetic field device for the preservation chamber 3: The Helmholtz coils 21 of the magnetic field generator 2 are coaxially distributed on the outside of the wall of the preservation chamber 3, and the distance between the two coils 21 is sufficient to ensure that the magnetic field uniformly covers the detection of the pork chunks 9 of a preset weight; a cooling fan 8 is installed at the top opening 32 of the preservation chamber 3, and the magnetic field is adjusted so that the magnetic induction intensity uniformity error in the central processing area meets the preset requirements. The preservation compartment 3 is equipped with a temperature and humidity sensor 7, and is at a preset distance from the pork chunks 9 placed on the central processing area. S2: Set magnetic field control parameters: Based on the quality and preservation time of the pork chunk 9, the magnetic field action time, magnetic field action mode, magnetic field strength, and frequency are set. The magnetic field action time includes a pre-target time period, which is the set time period during which the magnetic field begins to continuously act on the pork chunk 9. S3: Preservation magnetic field control and monitoring: According to the preset magnetic field action mode and parameters, the main control unit 5 controls the coil to generate a magnetic field, controls the cooling fan 8 to work, and obtains the temperature and humidity information transmitted by the temperature and humidity sensor 7 of the internal space 31 of the preservation compartment 3 in real time. If the temperature and humidity exceed the preset range, the main control unit 5 automatically adjusts the frequency for protection. S4: Timed detection of pork chunk 9: After the main control unit 5 controls the magnetic field to continue to act on the previous target time period, it detects the physicochemical indicators TBARs value, TVB-N value, pH value, water content and L*, a*, b* color sensory indicators of the pork chunk 9. The main control unit 5 obtains the measured values and compares them with the preset qualified values. S5: Based on the test results, determine whether the magnetic field parameters need to be adjusted. When the physical and chemical indicators fail to meet the requirements, the main control unit 5 automatically adjusts the current of the electromagnetic coil and the continuous / intermittent power supply mode until the test is passed. S6: Perform the preservation process: The main control unit 5 applies a magnetic field periodically according to a preset program within the preservation time, and dynamically adjusts the execution based on feedback from the temperature and humidity sensor 7.
[0024] The first preferred embodiment disclosed in this invention, such as Figures 2-4 As shown: This invention also discloses a magnetically controlled preservation system for pork, which implements a magnetically controlled preservation method for pork. The system includes a support frame 1, a preservation chamber 3 installed in the middle of the support frame 1, and two Helmholtz coils 21 symmetrically installed on the upper and lower outer walls of the preservation chamber 3. The magnetic field generator 2 uses a Helmholtz coil structure as the magnetic field source. The preservation chamber 3 has an internal space 31 in the middle, a top opening 32 at the top, side through holes 33 on the side walls, and a bottom through hole 34 at the bottom. A cooling device is installed at the top opening 32; in this embodiment, a cooling fan 8 is selected. A horizontal placement platform 4 is located in the bottom through hole 34 of the preservation chamber 3 for placing the pork piece 9 to be tested, and the vertical center line of the horizontal placement platform 4 coincides with the center lines of the two coils 21.
[0025] The preservation compartment 3 is also equipped with a temperature and humidity sensor 7 and a main control unit 5 electrically connected by a wire 6. A pair of temperature and humidity sensors 7 are symmetrically located on both sides of the pork block 9, and the distance H between the temperature and humidity sensors 7 and the pork block 9 should satisfy: 1.7cm ≤ H ≤ 2.3cm, with an optimal distance of 2cm. This ensures non-contact with the pork block 9, avoiding direct contact to prevent contamination and condensation interference. Simultaneously, it can accurately monitor temperature and humidity-related indicators, including coil temperature, and provide real-time feedback to the control unit 5M. Figure 3 As shown.
[0026] The main control unit 5 is also electrically connected to the coil 21 and the cooling fan 8. The main control unit 5 is equipped with a power module 51, a current regulation module 52, and a microcontroller 53. The microcontroller 53 includes a memory 531, a processor 532, and a computer program stored in the memory 531 and running on the processor 532. It controls the temperature and humidity sensor 7, the coil 21, and the cooling fan 8 to execute instructions and, in conjunction with the temperature and humidity information acquired in real time from the temperature and humidity sensor 7, adjusts the magnetic field environment in real time to meet the magnetization process of the pork chunk 9.
[0027] The second preferred embodiment disclosed in this invention, such as Figures 1-4 As shown: A magnetic preservation method for pork includes the following steps: S1: Preparation of the magnetic field device for the preservation chamber 3: The Helmholtz coil structure is selected as the magnetic field generator 2. The two coils 21 of the magnetic field generator 2 are coaxially and symmetrically distributed outside the wall of the preservation chamber 3. The distance between the two coils 21 can meet the detection requirements of uniform magnetic field coverage of the preset mass of pork chunks 9. In this embodiment, a commonly used pork chunk 9 with a mass of 2-5kg is selected. The distance between the two coils 21 is equal to the coil radius of 10cm. The uniform magnetic field area formed by the coil 21 with a radius of 10cm can just cover the volume of the commonly used 2-5kg pork chunk 9, ensuring that the whole piece of meat can be subjected to a stable magnetic field, which avoids insufficient local preservation effect and does not increase power consumption. The coil 21 has 150 turns and is wound with high-purity enameled copper wire with a diameter of 1mm. The wire is covered with a high-temperature resistant insulation layer to ensure electrical insulation performance and long-term stable operation. The magnetic field strength is controlled by an external adjustable DC power supply or a low-frequency alternating power supply. The current adjustment range is 0-2.0 A, realizing intelligent control of the magnetic field strength from 0 to 10 mT. The central area can form an adjustable magnetic field strength of about 10 mT. The magnetic field strength is calculated by formula (3): (3) In the formula: B represents the magnetic field strength, measured in Tesla (T). μ0 is the free permeability, which is a constant, μ0 = 4π × 10⁻⁶. -7 Newton / Ampere; N represents the number of turns in the coil, measured in turns. I represents the coil current, measured in amperes (A). L is the effective length of the coil, in meters (m).
[0028] A cooling fan 8 is installed at the top opening 32 of the preservation compartment 3. The active ventilation reduces heat accumulation in the device, maintains stable system operation, and ensures that the coil temperature rise is ≤15℃ (full load condition).
[0029] At least one pair of temperature and humidity sensors 7 are placed inside the preservation compartment 3, and are in a non-contact state with the pork chunks 9 placed in the central processing area. In this embodiment, a pair of temperature and humidity sensors 7 are symmetrically located on both sides of the pork chunks 9, and are at a preset distance from the pork chunks 9 placed on the horizontal placement platform 4 in the central processing area. In this embodiment, the preset distance H is selected to be 1.7cm≤H≤2.3cm, and the optimal distance H=2cm. This maintains a non-contact state with the pork chunks 9, avoiding direct contact to prevent contamination and condensation interference, while also being able to accurately monitor temperature and humidity-related indicators and coil temperature indicators in real time, and feed them back to the control unit 5 in real time. Figure 3 As shown.
[0030] A main control unit 5 is also provided. The main control unit 5 is connected to the temperature and humidity sensor 7, the magnetic field generator 2, and the cooling fan 8 via wires 6. The main control unit 5 is equipped with a power module 51, a current regulation module 52, and a microcontroller 53. The microcontroller 53 includes a memory 531, a processor 532, and a computer program stored in the memory 531 and running on the processor 532. It controls the temperature and humidity sensor 7, the coil 21, and the cooling fan 8 to execute instructions and, in conjunction with the real-time temperature and humidity information acquired by the temperature and humidity sensor 7, adjusts the environment in real time to meet the environmental requirements of the magnetization process of the pork chunk 9.
[0031] The uniformity error of magnetic induction intensity in the central processing area should satisfy ΔB≤±5%, and the uniformity error ΔB of magnetic induction intensity in the central processing area is calculated according to formula (1): ΔB=(B max -B min ) / B avg ×100% (1) In the formula: B max This represents the maximum magnetic field strength inside the cold storage compartment, expressed in tons (T). B min This represents the minimum magnetic field strength inside the cold storage compartment, expressed in tons (T). B avg The average magnetic field strength is expressed in tons (T).
[0032] Adjusting the magnetic field to ensure uniformity of magnetic induction intensity in the central processing area meets preset requirements can be achieved by optimizing the arrangement of coil 21 and adding a shielding layer (not shown in the figure). The shielding layer must be installed close to the Helmholtz coil, the magnetic field generator 2, because the Helmholtz coil is the core of the magnetic field generation, and its peripheral magnetic field is easily affected by external environmental factors such as metal components and other electromagnetic devices, leading to uneven magnetic field distribution within the preservation chamber 3, as detailed below: The shielding layer should be wrapped around the outside of the two Helmholtz coils, not the inside facing the preservation compartment, that is, covering the space between coil 21 and the outer wall of the preservation compartment 3. The shielding layer must not contact the coils or change their coaxial symmetry structure. The shielding layer is made of a high permeability material (such as permalloy or pure iron) to absorb or guide the edge magnetic field leaked from coil 21, reduce its disturbance to the uniform magnetic field in the central area, and at the same time avoid external electromagnetic signals from interfering with the magnetic field generated by the coil.
[0033] The magnetic field strength is controlled by an external adjustable DC power supply, namely power module 51 or current regulation module 52, to meet the preservation requirements of the pork chunk 9. Power module 51 generates a constant magnetic field with stable strength and direction that does not change over time. The magnetic field can continuously act on the pork chunk 9, destroying the microbial cell membrane structure through stable magnetic field lines, which is suitable for scenarios that require long-term and continuous inhibition of microbial reproduction. Current regulation module 52 generates an alternating magnetic field with periodic changes in strength and direction over time. The alternating magnetic field can more efficiently interfere with enzyme activity and enhance the inhibitory effect on fat oxidation, which is especially suitable for preservation stages that require simultaneous delay of oxidation reactions.
[0034] S2: Set magnetic field control parameters: Based on the quality and preservation time of the pork chunk 9, the magnetic field action time, magnetic field action mode, magnetic field strength, and frequency are set. The magnetic field action time includes a pre-target time period, which is the set time period during which the magnetic field begins to continuously act on the pork chunk 9. In this embodiment, commonly used 2-5kg pork chunks are selected 9, and the preservation time, i.e. the magnetic field effect time, is 21 days. The target time period is set to 30-60 minutes. The magnetic field effect mode includes a constant magnetic field and a phased-controlled intermittent magnetic field mode. The magnetic field strength is set to 0-10 mT and the frequency to 10-100 Hz. The main control unit 5 runs a computer program to realize intelligent control of the magnetic field.
[0035] S3: Preservation magnetic field control and monitoring: Based on the preset magnetic field operation mode and parameters, the main control unit 5 controls the coil 21 to generate a magnetic field, controls the cooling fan 8 to work, and acquires the temperature and humidity information transmitted by the temperature and humidity sensor 7 in the internal space 31 of the preservation chamber 3 in real time. The preset temperature range is -3.5 to 4℃, and the temperature rise of the coil 21 is ≤15℃. The preset humidity range is 80 to 95% RH. If the temperature and humidity exceed the preset range, the main control unit 5 will automatically adjust the frequency for protection.
[0036] S4: Timed detection of pork chunk 9: The main control unit 5 controls the magnetic field to continue acting for the target time period. In this embodiment, after acting for 45 minutes, the pork chunks 9 are manually tested for physicochemical indicators TBARs, TVB-N, pH, water content, and L*, a*, and b* color sensory indicators. The thiobarbituric acid reactant TBARs value should be less than 0.5 mg MDA / kg, the total volatile basic nitrogen TVB-N should be less than 15 mg / 100g, the pH value should not be greater than 6.2, and the water content loss should not be greater than 5%. The L*, a*, and b* values are measured by a colorimeter and together describe the characteristics of meat color. The L* value is between 35 and 53, the a* value does not exceed 15, and the b* value does not exceed 10.
[0037] The TBARs value is calculated according to formula (2): TBARs =(A532-A600) / m×9.48 (2) In the formula: TBARs are thiobarbituric acid reactants, with units of mg MDA / kg; A532 is the absorbance of the sample at a wavelength of 532 nm, expressed in L / (g·cm). A600 is the absorbance of the sample at a wavelength of 600 nm, with background correction, and the unit is L / (g·cm). M represents the sample mass, in grams. 9.48 is the molar absorptivity, unit: L·mol⁻¹ -1 ·cm -1 .
[0038] Table 1 shows the reasons for the unqualified physicochemical indicators of pork chunks (item 9) and the corresponding adjustment measures.
[0039] Table 1
[0040] The main control unit 5 acquires the measured value and compares it with the preset qualified value. Based on the test results and procedures, it makes adaptive adjustments to the magnetic field.
[0041] The purpose of setting the target time period is to set, verify, and adjust the magnetic field parameters for the meat to be preserved. Through this process, the optimal magnetic field preservation parameters for the meat can be obtained.
[0042] S5: Based on the test results, determine whether the magnetic field parameters need to be adjusted. When the physical and chemical indicators fail to meet the requirements, the main control unit 5 automatically adjusts the current magnitude and continuous / intermittent power supply mode of the electromagnetic coil 21, including: according to the different physical and chemical indicators that exceed the standards, selecting and adjusting one or more of the following: magnetic field strength, frequency, number of daily treatments, single magnetic field action time, humidity, constant magnetic field mode and intermittent magnetic field mode, until the test is qualified.
[0043] The initial total processing cycle is 30-60 minutes, followed by a 21-day preservation period. During the preservation period, the processing is performed 1-2 times daily. The magnetic field strength of the coil during the 21-day working period is 0-10 mT, and the frequency is 20-50 Hz. During the intermittent period, the magnetic field strength is 0 mT. The process is divided into the initial target time period (30-60 minutes, 10 minutes of operation + 5 minutes of intermittent operation) and the continuous preservation stage (1-21 days, 5 minutes of operation once a day + 25 minutes of intermittent operation or 3 minutes of operation twice a day + 15 minutes of intermittent operation).
[0044] S6: Perform the preservation process: The main control unit 5 applies a magnetic field periodically according to a preset program within the preservation period, and performs dynamic control through real-time feedback from the temperature and humidity sensor 7. This includes: dynamically adjusting the cycle and parameters based on the real-time monitoring results of the temperature and humidity sensor 7, executing through program preset and closed-loop feedback, and simultaneously coordinating the adjustment of the cooling fan 8. This can achieve a preservation effect of more than 21 days and meet the requirements of low power consumption.
[0045] Total energy consumption is calculated according to formula (3): P=I 2 ·R·t (3) In the formula: P represents total energy consumption, measured in joules (J). I is the coil current, in A; R is the resistance of a single coil, in ohms (Ω). T represents the single preservation time, in seconds (s).
[0046] Compared with traditional pork preservation methods such as low-temperature refrigeration, freezing, or the addition of chemical preservatives, this magnetic control preservation method has significant advantages in energy saving and environmental protection. For preserving 2-5 kg of pork chunks, traditional refrigeration usually requires continuous cooling at 4°C, with an average annual energy consumption of about 0.3–0.5 kWh / kg·day. Freezing requires a deep cryogenic environment of -18°C, with an annual energy consumption of over 1.0 kWh / kg·day. This magnetic control preservation method and system consumes less than 0.15 kWh / kg·day per day, achieving energy savings of up to 60%.
[0047] The embodiments of the present invention have been described above with reference to the accompanying drawings. However, the present invention is not limited to the specific embodiments described above. The specific embodiments described above are merely illustrative and not restrictive. Those skilled in the art can make many other forms under the guidance of the present invention without departing from the spirit and scope of the claims, and all of these forms are within the protection scope of the present invention.
Claims
1. A magnetic preservation method for pork, characterized in that: Includes the following steps: S1: Preparation of the magnetic field device for the cold storage: Helmholtz coils are coaxially distributed on the outside of the preservation chamber wall, and the distance between the two coils is sufficient to ensure that the magnetic field uniformly covers the pork pieces of the preset weight. A wind-cooling device is installed at the top opening of the preservation chamber, and the magnetic field is adjusted to ensure that the magnetic induction intensity in the central processing area is uniform and meets the preset requirements. The refrigeration compartment is equipped with a temperature and humidity sensor, and is spaced at a preset distance from the pork pieces placed on the central processing area. S2: Set magnetic field control parameters: The magnetic field action time, magnetic field action mode, magnetic field strength, and frequency are set according to the quality and preservation time of the pork chunks. The magnetic field action time includes a pre-target time period, which is the set time period during which the magnetic field begins to continuously act on the pork chunks. S3: Preservation magnetic field control and monitoring: According to the preset magnetic field action mode and parameters, the control coil generates a constant or alternating magnetic field to control the operation of the air-cooling device. It also acquires the temperature and humidity information transmitted by the temperature and humidity sensor in the preservation chamber in real time. If the temperature or humidity exceeds the preset range, it automatically adjusts the frequency for protection. S4: Timed detection of pork chunks: After the magnetic field continues to act on the target time period, the physicochemical indicators TBARs value, TVB-N value, pH value, water content and L*, a*, b* color sensory indicators of the pork chunks are detected, the measured values are obtained and compared with the preset qualified values; S5: Based on the test results, determine whether the magnetic field parameters need to be adjusted. When the physical and chemical indicators fail to meet the requirements, the current of the electromagnetic coil and the continuous / intermittent power supply mode are automatically adjusted until the test is passed. S6: Perform the preservation process: A magnetic field is applied periodically according to a preset program within the preservation period, and the operation is dynamically controlled by feedback from temperature and humidity sensors.
2. The magnetic preservation method for pork according to claim 1, characterized in that: In S1, at least one pair of sensor modules are provided, symmetrically located on both sides of the pork block, and are in a non-contact state with the pork block placed in the central processing area.
3. The magnetic preservation method for pork according to claim 2, characterized in that: In S1, the magnetic field is adjusted to ensure that the uniformity error of the magnetic induction intensity in the central processing area meets the preset requirements. This includes controlling the magnetic field strength through an external adjustable DC power supply or a low-frequency alternating power supply to meet the preservation requirements of the pork chunks, and ensuring that the uniformity error of the magnetic induction intensity in the central processing area ΔB ≤ ±5%, calculated according to the following formula: ΔB=(B max -B min ) / B avg ×100% In the formula, B max This represents the maximum magnetic field strength inside the cold storage compartment, expressed in tons (T). B min This represents the minimum magnetic field strength inside the cold storage compartment, expressed in tons (T). B avg The average magnetic field strength is expressed in tons (T).
4. The magnetic preservation method for pork according to claim 1, characterized in that: In S2, the magnetic field action mode includes a constant magnetic field and a phased-controlled intermittent magnetic field mode. The target time period is set to 30-60 minutes.
5. The magnetic preservation method for pork according to claim 1, characterized in that: In S3, the preset temperature range is -3.5 to 4℃, and the coil temperature rise is ≤15℃, and the humidity range is 80 to 95% RH.
6. The magnetic preservation method for pork according to claim 1, characterized in that: In S4, the physicochemical properties should meet the following requirements: TBARs less than 0.5 mg MDA / kg, total volatile basic nitrogen (TVB-N) less than 15 mg / 100g; pH not greater than 6.2; water loss not greater than 5%; no abnormal color change, with L* value between 35 and 53, a* value not exceeding 15, and b* value not exceeding 10; TBARs values are calculated using the following formula: TBARs = (A532-A600) / m × 9.48 In the formula: TBARs are thiobarbituric acid reactants, with units of mg MDA / kg; A532 is the absorbance of the sample at a wavelength of 532 nm, expressed in L / (g·cm). A600 is the absorbance of the sample at a wavelength of 600 nm, with background correction, and the unit is L / (g·cm). M represents the sample mass, in grams. 9.48 is the molar absorptivity, unit: L·mol⁻¹ -1 ·cm -1 .
7. The magnetic preservation method for pork according to claim 1, characterized in that: In S5, when the physical and chemical indicators are not up to standard, the current magnitude of the electromagnetic coil and the continuous / intermittent power supply mode are automatically adjusted, including: according to the different physical and chemical indicators that exceed the standard, one or more of the following are selected: magnetic field strength, frequency, number of daily treatments, single magnetic field action time, humidity, constant magnetic field mode and intermittent magnetic field mode.
8. The magnetic preservation method for pork according to claim 1, characterized in that: In S6, a magnetic field is periodically applied according to a preset program within the preservation time, and dynamic control is implemented through feedback from temperature and humidity sensors. This includes: combining real-time monitoring results from temperature and humidity sensors to dynamically adjust the cycle and parameters, implementing the program through preset and closed-loop feedback, while coordinating the adjustment of the air-cooling device, and ensuring that the overall power consumption meets the preset requirements.
9. A magnetically controlled preservation system for pork, characterized in that: The method for implementing the magnetically controlled preservation of pork according to any one of claims 1-8 includes a support frame, a preservation chamber installed in the middle of the support frame, and two Helmholtz coils symmetrically installed on the upper and lower outer walls of the preservation chamber; the preservation chamber has an internal space in the middle, a top opening at the top, side through holes on the side walls, and a bottom through hole at the bottom; a cooling device is installed at the top opening, and a horizontal placement platform for placing the pork piece to be tested is provided in the bottom through hole, and the vertical center line of the horizontal placement platform coincides with the center lines of the two coils.
10. The magnetically controlled preservation system for pork according to claim 9, characterized in that: The preservation compartment is also equipped with an electrically connected temperature and humidity sensor and a main control unit; there is a pair of temperature and humidity sensors, symmetrically located on both sides of the pork block, and the distance H between them and the pork block should satisfy: 1.7cm≤H≤2.3cm; The main control unit is also electrically connected to the coil and the air-cooling device. The main control unit is equipped with a power supply module, a current regulation module, and a microcontroller. The microcontroller includes a memory, a processor, and a computer program stored in the memory and capable of running on the processor to control the temperature and humidity sensor, the coil, and the air-cooling device to execute commands.