A method for preventing mildew of peanuts by using a programmed magnetic field

Abstract

The present invention discloses a method for preventing mildew of peanuts by using a programmed magnetic field, belonging to the technical field of agricultural product storage. By controlling the temperature and humidity of peanut storage and combining with the action of the programmed magnetic field, the growth of molds and the deterioration of quality during peanut storage are inhibited, thereby reducing the total number of molds and the toxin content on the peanut surface. Compared with the control group without programmed magnetic field treatment, after 90 days of storage, the total number of molds of peanuts is reduced by about 75-99.5%, and the aflatoxin is reduced by about 80.2-99.9%. Therefore, this method has good effects in the ambient temperature storage of peanuts, and is energy-saving, environmentally friendly, low-cost and highly safe, with broad prospects for industrial application.

Description

Technical Field

[0001] The present invention relates to a method for preventing peanuts from mildewing by using a programmed magnetic field, and belongs to the technical field of agricultural product storage. Background Art

[0002] Peanuts, belonging to the legume family, are annual herbaceous plants. Their fruits are rich in protein (25%-36%), fat (40%), vitamins and minerals, and are mainly used as food, oil, feed, etc. They are one of the widely cultivated and commonly consumed cash crops. However, the rich protein and fat in peanuts can also serve as a natural medium for the growth of microorganisms. Therefore, they are prone to insect infestation, mildew, and aging and deterioration during storage, which will affect their edible value. Some grain storage, transportation and safety control standards, such as GB22508-2016 "Hygienic Specifications for the Storage and Transportation of Raw Grain" and GB 31653-2021 "Specification for the Control of Aflatoxin Contamination in Foods", etc., regulate the environmental temperature, humidity, light, water content and other parameters of grain storage, thus providing a reference for the prevention of peanut mildew during storage. However, due to factors such as regional temperature and humidity differences and the heat generation and humidity increase in the grain pile caused by the aerobic respiration of peanuts, peanuts are prone to local mildew or deterioration during storage. For this reason, scientists have tried to control the environmental conditions of peanut storage through various technical methods to improve their storage quality and extend the storage period.

[0003] At present, the technical methods for preventing peanut mildew mainly include refrigeration, drying, controlled atmosphere, irradiation, and adding chemical preservatives. Among them, refrigeration and drying storage mainly inhibit peanut respiration and fungal growth by controlling the environmental conditions of low temperature, low humidity, ventilation and the extremely low water content of peanuts. They are the most commonly used and simple methods, but they have high energy consumption and are not easy to control the environmental conditions. Controlled atmosphere storage is a method of extending the storage period of peanuts by changing the gas composition of the storage environment. By reducing the oxygen content in the storage environment to less than 2% and increasing the carbon dioxide content to more than 40%, peanut respiration can be better inhibited and local mildew can be reduced. However, it has high requirements for airtight materials and the airtightness of the environment, so the required cost and energy consumption are also relatively large. In addition, irradiating peanuts with ultraviolet light or adding chemical preservatives such as sorbic acid and propionic acid can kill the microorganisms on the peanut surface and inhibit their growth and reproduction, thus achieving the purpose of preventing mildew and insects, but there are certain safety hazards.

[0004] As a non-contact auxiliary storage means, the magnetic field has the characteristics of strong penetration, green safety, no pollution, etc. for peanuts, and can inhibit the growth and metabolism of microorganisms by generating biological effects. Therefore, it has certain potential in the application of peanut storage and mildew prevention. However, the existing magnetization treatment methods usually involve continuously applying a high-intensity steady magnetic field treatment, which has high energy consumption and a cumbersome implementation process. Summary of the Invention

[0005] In view of the above deficiencies in the prior art, the present invention provides a method for preventing mildew of peanuts by using a programmed magnetic field. By setting the working parameters of the magnetic field, the antioxidant capacity of peanuts is improved and their storage resistance is enhanced under the action of the programmed magnetic field environment. Moreover, the magnetic flux change caused by the rising and falling edges of the magnetic field can generate eddy currents inside and outside the microbial cell membrane, thereby significantly inhibiting the growth of molds and the synthesis of toxins during peanut storage.

[0006] The programmed magnetic field refers to the magnetic field generated by the excitation coil arranged on the coil frame under the control of a control circuit. The control means passing a steady or alternating current, continuously outputting a constant or sine wave signal, and the magnetic field parameters are regulated by a program.

[0007] The prevention of mildew refers to inhibiting the germination and growth of spores of molds such as Aspergillus and Penicillium on the surface of peanuts. The prevention of mildew is mainly manifested as inhibiting the growth and reproduction of molds, especially Aspergillus flavus. The total number of molds on the surface of peanuts is controlled within the safety limit specified by the national safety standard, and no aflatoxin B1 is detected.

[0008] The method of the present invention is applicable to shelled peanut kernels that have been pretreated without mildew, insect damage, impurities, and the total surface colony count does not exceed the national safety limit.

[0009] The method for preventing mildew of peanuts by using a programmed magnetic field according to the present invention mainly includes the following steps:

[0010] (1) Sort the peanuts, and the water content of the peanuts used for storage is 6%-8%;

[0011] (2) Package the peanuts sorted in step (1) in a breathable container;

[0012] (3) Place the breathable container described in step (2) in a programmed magnetic field environment with a temperature of 15-25°C and a humidity of 60%-70% for 4 days, and then turn off the programmed magnetic field; the programmed magnetic field is generated by a steady or alternating current, the rising edge of the magnetic field waveform is 0.1-0.3 mT / s, the stable time is 0.01-3 s, the falling edge of the magnetic field waveform is 0.1-0.3 mT / s, and the magnetic field intensity is 0.2-5 mT.

[0013] In one embodiment, the sorting described in step (1) is to screen the peanuts with a 20-40 mesh sieve, and remove the mildewed, germinated, damaged, insect-eaten grains and impurities such as sand, iron blocks, and plant leaves and stems by machine or manual sorting.

[0014] In one embodiment, the breathable container described in step (2) is a woven bag, a plastic-sealed bag, or other plastic or glass containers with air holes.

[0015] In one embodiment, the programmed magnetic field described in step (3) is started when storing peanuts and turned off after acting continuously for 4 days.

[0016] In one implementation method, in step (3), the breathable container described in step (2) is stored under a programmed magnetic field with a temperature of 15 °C, a humidity of 60%, a magnetic field strength of 5 mT, a rising edge of the magnetic field waveform of 0.3 mT / s, a stabilization time of 1 s, and a falling edge of the magnetic field waveform of 0.3 mT / s for 4 days, and then the programmed magnetic field is turned off.

[0017] Beneficial effects:

[0018] The present invention uses a programmed magnetic field as an auxiliary means to propose a new peanut storage and mold prevention technology. Through the treatment of the programmed magnetic field, the growth of molds during peanut storage can be inhibited, the content of surface mycotoxins can be reduced, and the antioxidant capacity of peanuts can be improved, thereby extending the storage time and improving the storage quality. After storage for up to 90 days, the treatment with the programmed magnetic field can reduce the total number of surface molds of peanuts to 3×10 3 CFU / g, which is two orders of magnitude lower than the mold contamination of the control group without magnetic field treatment, and aflatoxin B1 is not detected, so it can be determined that the mold prevention effect is achieved.

[0019] Compared with the existing high-strength and steady magnetic field magnetization treatment means, the present invention induces "electric surges" in microbial cells by designing the rising edge and falling edge of the programmed magnetic field waveform, can achieve the inhibition of the growth and metabolism of molds under a low-strength magnetic field, and the magnetic field parameters can be regulated by a program, and a good mold prevention effect can be achieved under a low-strength programmed magnetic field. Therefore, the energy consumption is lower, the safety is higher, and the operation is more convenient. Brief description of the drawings

[0020] Figure 1 It is a comparison physical diagram of the mildew conditions of peanuts stored for 90 days under the application of a 5 mT programmed magnetic field and without the application of a magnetic field under the environmental conditions of a temperature of 15 °C and a humidity of 60%.

[0021] Figure 2 Schematic diagram of the programmed magnetic field waveform.

[0022] Figure 3 Schematic diagram of the ordinary steady magnetic field waveform. Specific implementation manners

[0023] Mold counting: The determination method is carried out according to the method in GB 4789.15-2016 "Food microbiological examination - Enumeration of molds and yeasts".

[0024] Determination of aflatoxin B1 content: Detection is carried out by high performance liquid chromatography - pre-column derivation method, and the detection method is carried out according to the method in GB5009.22-2016 "Determination of aflatoxin B and G in foods".

[0025] Example 1

[0026] Program-controlled magnetic field treatment group:

[0027] (1) Screen the dry peanuts using a 20-mesh sieve, and manually remove the mildewed, germinated, damaged, insect-eaten grains, as well as impurities such as sand, iron blocks, and plant leaf stems. According to the direct drying method in GB5009.3-2016, the moisture content of the peanuts was measured to be 6.7%.

[0028] (2) Accurately weigh 2 kg of the dry peanuts obtained in step (1) into a clean breathable plastic-sealed bag.

[0029] (3) After sterilizing the inner cavity of the magnetic field test chamber with an ultraviolet lamp for 30 min, set the parameters. Set the rising edge of the magnetic field waveform to 0.3 mT / s, the stabilization time to 1 s, and the falling edge of the magnetic field waveform to 0.3 mT / s through the digital display control panel. The schematic diagram of the magnetic field waveform is as shown in Figure 2 . Place the breathable plastic-sealed bag containing peanuts into the magnetic field test chamber, control the magnetic field intensity of the program-controlled magnetic field to be 5 mT, the temperature to be 15 °C, and the humidity to be 60%. The program-controlled magnetic field is started when the peanuts are placed in the magnetic field test chamber and is turned off after acting for 4 days. The peanuts are stored for a total of 90 days.

[0030] After the storage is completed, observe the mycelial growth on the surface of the peanuts, and measure the mold count and the content of aflatoxin B1. The results show that: after 90 days of storage, no obvious mold mycelia were found on the surface of the peanuts. After testing, the total mold count was 3×10 3 CFU / g, and aflatoxin B1 was not detected, indicating that under these conditions, the peanuts have good storage quality.

[0031] Control group:

[0032] (1) The same as the experimental group.

[0033] (2) The same as the experimental group.

[0034] (3) After sterilizing the inner cavity of the magnetic field test chamber with an ultraviolet lamp for 30 min, place the breathable plastic-sealed bag containing peanuts into the magnetic field test chamber, with the temperature being 15 °C and the humidity being 60%. Do not turn on the program-controlled magnetic field. The peanuts are stored for a total of 90 days.

[0035] The results show that: on the surface of the peanuts in the control group, there were more mold mycelia. The total mold count was approximately 6×10 5 CFU / g, which was about 200 times more than that in the magnetic field treatment group. Moreover, the content of aflatoxin B1 reached 21.89 μg / kg, exceeding the national standard (GB 2761-2017) for the limit of aflatoxin B1 in peanuts and their products, which is 20 μg / kg.

[0036] The above results indicate that the 5mT programmed magnetic field treatment can inhibit the mildew of peanuts, significantly reducing the number of molds on the peanut surface and the content of aflatoxin B1.

[0037] Example 2

[0038] Refer to the programmed magnetic field treatment group in Example 1, with the difference that the temperature in step (3) is adjusted to 25°C.

[0039] The results show that the total number of molds on the peanut surface is 1.1×10 4 CFU / g, which is about 2.7 times more than that in the programmed magnetic field treatment group of Example 1. The content of aflatoxin B1 detected is 3.46 μg / kg, but the degree of contamination is relatively light.

[0040] Example 3

[0041] Refer to the programmed magnetic field treatment group in Example 1, with the difference that the programmed magnetic field intensity in step (3) is adjusted to 3mT.

[0042] The results show that the total number of molds on the peanut surface is 8×10 3 CFU / g, which is about 1.7 times more than that in the programmed magnetic field treatment group of Example 1. The content of aflatoxin B1 detected is 1.64 μg / kg, but the degree of contamination is relatively light.

[0043] Example 4

[0044] Refer to the programmed magnetic field treatment group in Example 1, with the difference that the humidity in step (3) is adjusted to 70%.

[0045] The results show that the total number of molds on the peanut surface is 1.3×10 4 CFU / g, which is about 3.3 times more than that in the programmed magnetic field treatment group of Example 1. The content of aflatoxin B1 detected is 4.32 μg / kg, but the degree of contamination is relatively light.

[0046] Comparative Example 1

[0047] Refer to the programmed magnetic field treatment group in Example 1, with the difference that in step (1), the peanuts were not sorted to remove the moldy, germinated, damaged, and insect-eaten grains.

[0048] The results show that the total number of molds on the peanut surface is 1.7×10 5 CFU / g, which is about 56 times more than that in the programmed magnetic field treatment group of Example 1. The content of aflatoxin B1 detected is 9.26 μg / kg, and the degree of contamination is medium, indicating that when there are mildewed or insect-eaten samples in the peanuts, with the extension of the storage time, the inhibitory effect of the programmed magnetic field on the growth of molds will gradually weaken.

[0049] Comparative Example 2

[0050] Refer to the programmed magnetic field treatment group in Example 1, with the difference that the temperature is adjusted to 25 °C in step (3), and the programmed magnetic field is not activated during the entire storage process.

[0051] The results show that the total number of surface molds on peanuts is 7.5×10 5 CFU / g, which is about 250 times more than that of the programmed magnetic field treatment group in Example 1. Moreover, the detected content of aflatoxin B1 is 27.15 μg / kg, and the pollution degree is serious, exceeding the national safety standard limit of 20 μg / kg.

[0052] Comparative Example 3

[0053] Refer to the programmed magnetic field treatment group in Example 1, with the difference that the humidity is adjusted to 70% in step (3), and it is not activated during the entire storage process.

[0054] The results show that the total number of surface molds on peanuts is 7×10 5 CFU / g, which is about 230 times more than that of the programmed magnetic field treatment group in Example 1. Moreover, the detected content of aflatoxin B1 is 25.12 μg / kg, and the pollution degree is serious, exceeding the national safety standard limit of 20 μg / kg.

[0055] Comparative Example 4

[0056] Refer to the programmed magnetic field treatment group in Example 1, with the difference that in step (3), the rising and falling edges of the programmed magnetic field waveform are not enabled, and only the magnetic field type is set as a static magnetic field with a magnetic field intensity of 5 mT. The schematic diagram of the used magnetic field waveform is as Figure 3 shown.

[0057] The results show that the total number of surface molds on peanuts is 5.6×10 5 CFU / g, which is about 180 times more than that of the programmed magnetic field treatment group in Example 1. Moreover, the detected content of aflatoxin B1 is 19.85 μg / kg, and the pollution degree is serious, indicating that under the same magnetic field intensity, the effect of the programmed magnetic field is much better than that of the ordinary steady magnetic field.

[0058] Comparative Example 5

[0059] Refer to the programmed magnetic field treatment group in Example 1, with the difference that in step (3), the programmed magnetic field intensity is adjusted to 0.1 or 10 mT, and the rising and falling edges of the magnetic field waveform are still 0.3 mT / s, and the stable time is still 1 s.

[0060] The results show that when the programmed magnetic field intensity is 0.1 mT, the total number of surface molds on peanuts is 2.5×10 5CFU / g, which is about 80 times more than that of the programmed magnetic field treatment group in Example 1, and the content of aflatoxin B1 detected is 9.85 μg / kg, with a medium pollution level; when the programmed magnetic field intensity is 10 mT, the total number of molds on the peanut surface is 3.6×10 5 CFU / g, which is about 120 times more than that of the programmed magnetic field treatment group in Example 1, and the content of aflatoxin B1 detected is 15.33 μg / kg, indicating that only within the appropriate magnetic field intensity and frequency range can the programmed magnetic field play a better anti-mold role.

[0061] Comparative Example 6

[0062] Referring to the programmed magnetic field treatment group in Example 1, the difference is that in step (3), the rising edge and falling edge of the programmed magnetic field waveform are both adjusted to 0.4 mT / s, and the stable time is still 1 s.

[0063] The results show that the total number of molds on the peanut surface is 1.2×10 4 CFU / g, which is about 3 times more than that of the programmed magnetic field treatment group in Example 1, and the content of aflatoxin B1 detected is 3.64 μg / kg, indicating that when the rising edge and falling edge of the magnetic field waveform increase and exceed the appropriate range, the inhibitory effect of the relatively fast magnetic flux change on the growth and metabolism of molds will weaken.

Claims

1. A method for preventing mildew of peanuts by using a programmed magnetic field, characterized in that, It mainly includes the following steps: (1) Sort the peanuts. The moisture content of the peanuts for storage after sorting is 6%-8%; The sorting is to screen the peanuts with a 20-40 mesh sieve, and remove the mildewed, germinated, damaged, insect-eaten grains, as well as impurities such as sand, iron blocks, and plant leaves and stems by machine or manual sorting; (2) Package the sorted peanuts in step (1) in a breathable container; (3) Place the breathable container in step (2) in a programmed magnetic field environment with a temperature of 15-25°C and a humidity of 60%-70% for 4-5 days, and then turn off the programmed magnetic field; the programmed magnetic field is generated by an alternating current, the rising edge of the magnetic field waveform is 0.1-0.3 mT / s, the stable time is 0.01-3 s, the falling edge of the magnetic field waveform is 0.1-0.3 mT / s, and the magnetic field strength is 0.2-5 mT; The programmed magnetic field refers to the magnetic field generated by the excitation coil arranged on the coil frame under the control of the control circuit. The control means passing an alternating current, continuously outputting a sine wave signal, and the magnetic field parameters are regulated by a program.

2. A method for preventing mildew of peanuts by using a programmed magnetic field according to claim 1, characterized in that, The breathable container in step (2) is a woven bag, a plastic-sealed bag, or other plastic or glass containers with air holes.

3. A method for preventing mildew of peanuts by using a programmed magnetic field according to claim 1, characterized in that, The programmed magnetic field in step (3) is started when the breathable container is put in and turned off after acting for 4 days.

4. A method for preventing mildew of peanuts by using a programmed magnetic field according to claim 1, characterized in that, The peanuts are shelled peanut kernels.

5. A method for preventing mildew of peanuts by using a programmed magnetic field according to claim 1, characterized in that, The temperature in step (3) is 15°C.

6. A method for preventing mildew of peanuts by using a programmed magnetic field according to claim 1, characterized in that, The humidity in step (3) is 60%.

7. A method for preventing mildew of peanuts by using a programmed magnetic field according to claim 1, characterized in that, In step (3), the magnetic field strength of the programmed magnetic field is 5 mT, the rising edge of the magnetic field waveform is 0.3 mT / s, the stable time is 1 s, and the falling edge of the magnetic field waveform is 0.3 mT / s.

8. A method for preventing mildew of peanuts by using a programmed magnetic field according to claim 1, characterized in that, The anti-mildew refers to inhibiting the germination and growth of spores of Aspergillus or Penicillium on the surface of peanuts.

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