Method for storing and preserving agricultural products or agricultural and sideline products

Abstract

The present invention discloses a method for storing and preserving agricultural products or agricultural and sideline products, and belongs to the technical field of agricultural product or agricultural and sideline product preservation. The method of the present invention uses a low-temperature environment to store and preserve agricultural products or agricultural and sideline products, and during storage, provides a periodic pulsed weak magnetic field to the environment in which the agricultural products or agricultural and sideline products are located; the magnetic field intensity of the weak magnetic field is 0.1 to 10 mT, and the temperature of the low-temperature environment is ‑5 to 15°C; the pulsed weak magnetic field has a frequency of 1 to 1 kHz and a duty cycle of 0.2 to 0.7; the periodic pulsed weak magnetic field has a ratio of the intermittent time of the magnetic field in each cycle of 1:1.5 to 1:4. The present invention effectively improves the preservation effect and saves costs by providing a specific periodic pulsed weak magnetic field to the environment in which the agricultural products or agricultural and sideline products are located when preserving them in a low-temperature environment; the method of the present invention is used to preserve cucumbers and yogurt, and the effect is very obvious.

Description

Technical Field

[0001] The invention relates to a method for storing and preserving agricultural products or agricultural and sideline products, and belongs to the technical field of agricultural product or agricultural and sideline product preservation. Background Art

[0002] Common storage and preservation methods primarily rely on temperature control, which slows the respiration and evaporation of agricultural products and by-products by reducing temperatures. However, during the storage phase, when large quantities of agricultural products and by-products are stacked and stored, some of the product tissues become damaged, and cell physiological and metabolic activity changes, microbial growth and infection can rapidly occur. This shortens the shelf life of agricultural products and by-products, increases waste, and degrades their quality, significantly impacting their supply chain.

[0003] There are reports of a method for extending the storage life of fruits and vegetables by combining magnetic fields with refrigeration. This method involves placing packaged fruit bags inside a fresh-keeping container with magnetically-enhanced iron shelves. The temperature is set between 3°C and 8°C, and the magnetic field strength is between 2mT and 7mT. This public report does not provide data on improved preservation compared to conventional storage. In fact, in previous research, the inventors found that controlling the magnetic field and coordinating other storage conditions significantly affects the preservation results.

[0004] Therefore, it is necessary to develop methods that can further improve the storage and preservation effects of agricultural products or agricultural by-products. Summary of the Invention

[0005] During the preliminary research process, the inventor team conducted an in-depth study on the effect of magnetic field environment on the preservation of agricultural products and agricultural by-products, and found that the control of magnetic field environment and the coordination of other storage conditions will have different unexpected effects on the preservation effect. Only by effectively controlling the magnetic field environment can the preservation effect be effectively achieved.

[0006] To address at least one of the aforementioned issues, the present invention provides a method for storing and preserving agricultural or by-products. By applying a specific periodic pulsed weak magnetic field to the environment in which the agricultural or by-products are stored during low-temperature storage, this method effectively improves preservation and reduces costs. The method has been shown to be highly effective in preserving cucumbers and yogurt.

[0007] The present invention provides a method for storing and preserving agricultural products or agricultural by-products, comprising: adopting a low-temperature environment to store and preserve the agricultural products or agricultural by-products, and providing a periodic pulsed weak magnetic field to the environment in which the agricultural products or agricultural by-products are located during the storage period; the magnetic field strength of the weak magnetic field is 0.1-10 mT, and the temperature of the low-temperature environment is -5-15°C; the frequency of the pulsed weak magnetic field is 1-1 kHz, and the duty cycle is 0.2-0.7; the ratio of the magnetic field interval time in each cycle of the periodic pulsed weak magnetic field is 1:1.5-1:4, that is, the pulsed weak magnetic field working time and the off time in each cycle are 1:(1.5-4).

[0008] Optionally, the magnetic field strength is 3-5 mT.

[0009] Optionally, the magnetic field frequency is 50-800 Hz.

[0010] Optionally, the duty cycle is 0.3.

[0011] Optionally, the ratio of the intermittent time of the magnetic field in each cycle is 1:2 to 1:2.5.

[0012] Optionally, the method further controls the relative humidity of the environment to be 65-95%.

[0013] Optionally, after the agricultural products or agricultural by-products are pre-cooled and reach a uniform fresh-keeping temperature, they are placed in a cold storage and stacked in a row, or in a cold room for small quantities.

[0014] Optionally, the periodic oscillating weak magnetic field is controlled by a weak magnetic field generating unit, which also includes a pulsed weak magnetic field power supply and a circuit control system. Optionally, the circuit control system adjusts at least one of the magnetic field intensity, frequency, duty cycle, and intermittent time ratio of the weak magnetic field to ensure that the environment meets the weak magnetic field requirements. The periodic oscillating weak magnetic field can be achieved using existing technologies, such as the device described in patent CN113192719A, which amplifies the conductors, weak magnetic field power supply, and circuit control module.

[0015] Optionally, the storage capacity of the agricultural products or agricultural and sideline products is 1 ton to 500 tons.

[0016] Optionally, the agricultural products include but are not limited to fruits and vegetables, edible fungi, raw tea, seedlings, grain and oil crops; the agricultural and sideline products include but are not limited to yogurt, flour, canned fruits and vegetables, tobacco leaves, and Chinese herbal medicines.

[0017] The present invention also provides a storage and preservation method for reducing the water loss rate and rot rate of cucumbers, comprising the following steps:

[0018] (1) Raw material pretreatment: After the cucumbers are harvested, rinse them with cold water until the temperature reaches below 10°C. After the surface moisture evaporates, wrap the cucumbers with plastic film and pack them into boxes. Place them in a cold storage and stack them in piles.

[0019] (2) Magnetic field storage and preservation: The cold storage adopts a periodic pulse weak magnetic field with a magnetic field strength of 5mT, a frequency of 50Hz, a duty cycle of 0.3, a ratio of the magnetic field interval time in each cycle of 1:2, a low temperature environment temperature of 10℃, a relative humidity of 95%, and storage and preservation.

[0020] Optionally, the magnetic field frequency is 5 to 600 Hz.

[0021] The present invention also provides a storage and preservation method for reducing the swelling rate of yogurt bags, comprising the following steps:

[0022] (1) Sterilize the yogurt, pack it in bags, and then pre-cool it to a temperature below 4°C. Then pack it in boxes and stack it in a cold storage;

[0023] (2) Magnetic field storage and preservation: The cold storage adopts a periodic pulse weak magnetic field with a magnetic field strength of 3mT, a frequency of 100Hz, a duty cycle of 0.4, and a ratio of the magnetic field interval time in each cycle of 1:2.5. The low temperature environment temperature is 4℃, the relative humidity is 65%, and the storage and preservation are carried out.

[0024] Optionally, the magnetic field frequency is 10 to 800 Hz.

[0025] Advantages and effects of the present invention:

[0026] (1) The method of the present invention effectively improves the preservation effect and saves costs by providing a specific intermittent pulsed weak magnetic field to the environment in which agricultural products or agricultural and sideline products are located when preserving them in a low-temperature environment. The method of the present invention is used to preserve cucumbers and yogurt, and the effect is very obvious.

[0027] (2) The method of the present invention shows that the selection of periodic pulsed weak magnetic field and the control of specific conditions have a great influence on the storage effect of agricultural products or agricultural and sideline products, especially the duty cycle, intermittent period, magnetic field intensity, etc., and a good preservation effect can only be achieved under reasonable conditions. DETAILED DESCRIPTION

[0028] In response to the numerous deficiencies of the prior art, the inventors of this case, after extensive research and extensive practice, have come up with the technical solutions of the present invention. However, it should be understood that, within the scope of the present invention, the above-mentioned technical features of the present invention and the technical features specifically described below (in the embodiments) can be combined with each other to form new or preferred technical solutions. Due to space limitations, they will not be detailed here.

[0029] In the following examples, unless otherwise specified, all raw materials, reagents, reaction equipment, testing equipment and methods used can be obtained through commercial purchase or other channels.

[0030] Example 1: A method for storing and preserving cucumbers

[0031] A method for storing and preserving cucumbers comprises the following steps:

[0032] S1. Raw material pretreatment: 2 tons of harvested cucumbers were rinsed with 0.5°C cold water for 20 minutes until the surface temperature reached 10°C. After the surface moisture evaporated, the cucumbers were wrapped in plastic film, packed into boxes, and stored in a cold storage facility in stacks. Randomly sample n0 cucumbers with intact skin and uniform shape and size, and measure their initial mass m0.

[0033] S2. Magnetic field storage and preservation: The cold storage uses a periodic pulsed weak magnetic field with a magnetic field strength of 5mT, a frequency of 50Hz, a duty cycle of 0.3, and a ratio of the magnetic field interval time in each cycle of 1:2. The low temperature environment is 10°C, and the relative humidity is 95%. The storage and preservation are carried out for 10 days, and the mass m1 of the n0 cucumbers sampled and the number of rotten cucumbers n1 are measured. When the rotten area of ​​the cucumbers exceeds 25%, they are considered rotten.

[0034] After the storage, the changes in cucumber water loss rate and rot rate were observed. The cucumber water loss rate = (m0-m1) / m0×100%, and the rot rate = (n0-n1) / n0×100%. 500 cucumbers were sampled, and the cucumber water loss rate was 4.28% and the rot rate was 2.2%.

[0035] Example 2: A method for storing and preserving cucumbers

[0036] A method for storing and preserving cucumbers comprises the following steps:

[0037] S1. Raw material pretreatment: 2 tons of harvested cucumbers were rinsed with 0.5°C cold water for 20 minutes until the surface temperature reached 10°C. After the surface moisture evaporated, the cucumbers were wrapped in plastic film, packed into boxes, and stored in a cold storage facility in stacks. Randomly sample n0 cucumbers with intact skin and uniform shape and size, and measure their initial mass m0.

[0038] S2. Magnetic field storage and preservation: The cold storage uses a periodic pulsed weak magnetic field with a magnetic field strength of 5mT, a frequency of 600Hz, a duty cycle of 0.3, and a ratio of the magnetic field interval time in each cycle of 1:2. The low temperature environment is 10°C and the relative humidity is 95%. The storage and preservation are carried out for 10 days, and the mass m1 of the n0 cucumbers sampled and the number of rotten cucumbers n1 are measured. When the rotten area of ​​the cucumbers exceeds 25%, they are considered rotten.

[0039] After the storage, 500 cucumbers were sampled, and the water loss rate was 5.22% (a relative change of 21.96% compared to Example 1), and the rot rate was 2.8% (a relative change of 27.3% compared to Example 1). Given a price of approximately 3.5 yuan per kilogram of cucumbers and a storage capacity of 2 tons, water loss and rot occurred during storage. The solution in Example 1 saved 104.2 yuan in costs compared to this solution.

[0040] Example 3: A method for storing and preserving cucumbers

[0041] A method for storing and preserving cucumbers comprises the following steps:

[0042] S1. Raw material pretreatment: 2 tons of harvested cucumbers were rinsed with 0.5°C cold water for 20 minutes until the surface temperature reached 10°C. After the surface moisture evaporated, the cucumbers were wrapped in plastic film, packed into boxes, and stored in a cold storage facility in stacks. Randomly sample n0 cucumbers with intact skin and uniform shape and size, and measure their initial mass m0.

[0043] S2. Magnetic field storage and preservation: The cold storage uses a periodic pulsed weak magnetic field with a magnetic field strength of 5mT, a frequency of 5Hz, a duty cycle of 0.3, and a ratio of the magnetic field interval time in each cycle of 1:2. The low temperature environment is 10℃, and the relative humidity is 95%. The storage and preservation are carried out for 10 days, and the mass m1 of the n0 cucumbers sampled and the number of rotten cucumbers n1 are measured. When the rotten area of ​​the cucumbers exceeds 25%, they are considered rotten.

[0044] After the storage, 500 cucumbers were sampled, and the water loss rate was 5.47% (a relative change of 27.80% compared to Example 1), and the rot rate was 2.7% (a relative change of 22.3% compared to Example 1). Given a price of approximately 3.5 yuan per kilogram for cucumbers and a storage capacity of 2 tons, water loss and rot occurred during storage. The solution in Example 1 saved 114.6 yuan in costs compared to this solution.

[0045] Comparative Example 1: Effects of different storage conditions on the preservation of cucumbers

[0046] Solution 1: The same raw materials as in Example 1 were used and subjected to the same pretreatment, and the cold storage environment was kept at a low temperature of 10° C. and a relative humidity of 95%, and the products were stored for 10 days (without applying a magnetic field).

[0047] Solution 2: Compared with Example 1, the duty cycle of S2 is adjusted to 0.1, and other conditions are consistent with Example 1.

[0048] Solution 3: Compared with Example 1, the duty cycle of S2 is adjusted to 0.8, and other conditions are consistent with Example 1.

[0049] Solution 4: Compared with Example 1, the ratio of the intermittent time of the magnetic field in each cycle of S2 is adjusted to 1:1, and other conditions are consistent with Example 1.

[0050] Solution 5: Compared with Example 1, the ratio of the intermittent time of the magnetic field in each cycle of S2 is adjusted to 1:5, and other conditions are consistent with Example 1.

[0051] Solution 6: Compared with Example 1, the pulsed weak magnetic field in S2 is adjusted to a constant weak magnetic field, specifically adjusted to a magnetic field intensity of 15 mT. Other conditions are consistent with Example 1.

[0052] The effects of different storage conditions on the preservation of cucumbers were compared. The changes in the water loss rate and rot rate of cucumbers during storage were observed with reference to the sampling method of Example 1, and the results were compared with those of Example 1. The results are shown in Table 1.

[0053] Table 1 Cucumber preservation effect under different storage conditions

[0054] Water loss rate Relative change rate of water loss rate Decay rate Relative change rate of decay rate Example 1 4.28％ - 2.2％ - Solution 1 9.29％ 117.06％ 11.4％ 418.2％ Option 2 7.88％ 84.11％ 5.4％ 145.5％ Option 3 8.32％ 94.39％ 5.0％ 127.3％ Option 4 7.94％ 85.51％ 5.0％ 127.3％ Option 5 8.02％ 87.38％ 5.9％ 168.2％ Option 6 6.47％ 51.17％ 3.9％ 77.3％

[0055] As shown in Table 1, excessively high or low magnetic field intensity, duty cycle, and intermittent period significantly affect the water loss and decay rate of cucumbers during storage. Cucumbers are rich in water molecules and organic biomacromolecules, which are diamagnetic. Under a suitable external magnetic field, these components undergo magnetization and orientation, reducing surface transpiration and dry loss, inhibiting microbial metabolic activity, and effectively reducing decay. However, when magnetic field parameters are too high or too low, the Lorentz force alters the diffusion and migration rates of various free ions in the fruit and vegetable, increasing the transmembrane ion transport flux, leading to water loss and increased water loss. This can also reduce the inhibitory effect on microbial enzyme activity and promote the growth of spoilage bacteria. Cucumbers cost about 3.5 yuan per kilogram, with a storage capacity of 2 tons. They lose water and rot during storage. The solution of Example 1 can save at least 927.2 yuan, 452.8 yuan, 456.3 yuan, 431.0 yuan, 494.3 yuan and 261.2 yuan in costs compared with other solutions, of which all the rotten parts are losses, and the remaining non-rotten parts are calculated as water loss.

[0056] Example 4

[0057] A method for storing fresh yogurt comprises the following steps:

[0058] S1. Raw material pretreatment: 5 tons of yogurt were sterilized, bagged, and pre-cooled to 4°C. They were then boxed and stacked in a cold storage. Randomly sampled from the bag were n0 bags with no surface damage or bulging.

[0059] S2. Magnetic field storage and preservation: The cold storage uses a periodic pulsed weak magnetic field with a magnetic field strength of 3mT, a frequency of 100Hz, a duty cycle of 0.4, and a ratio of the intermittent time of the magnetic field in each cycle of 1:2.5. The low temperature environment temperature is 4°C, the relative humidity is 65%, and the storage and preservation period is 30 days. The number of swollen bags n1 of the sampled n0 bags is measured. When the volume of the yogurt bag expands by more than 5%, it is considered to be swollen.

[0060] After the end, observe the changes in the bag swelling rate of yogurt storage, bag swelling rate = (n0-n1) / n0×100%, sample 1000 bags of yogurt, and no bag swelling.

[0061] Example 5

[0062] A method for storing fresh yogurt comprises the following steps:

[0063] S1. Raw material pretreatment: 5 tons of yogurt were sterilized, bagged, and pre-cooled to 4°C. They were then boxed and stacked in a cold storage. Randomly sampled from the bag were n0 bags with no surface damage or bulging.

[0064] S2. Magnetic field storage and preservation: The cold storage uses a periodic pulsed weak magnetic field with a magnetic field strength of 3mT, a frequency of 800Hz, a duty cycle of 0.4, and a ratio of the intermittent time of the magnetic field in each cycle of 1:2.5. The low temperature environment temperature is 4°C, the relative humidity is 65%, and the storage and preservation period is 30 days. The number of swollen bags n1 of the sampled n0 bags is measured. When the volume of the yogurt bag expands by more than 5%, it is considered to be swollen.

[0065] After the end, observe the changes in the bag swelling rate of yogurt storage, bag swelling rate = (n0-n1) / n0×100%, sample 1000 bags of yogurt, and no bag swelling.

[0066] Example 6

[0067] A method for storing fresh yogurt comprises the following steps:

[0068] S1. Raw material pretreatment: 5 tons of yogurt were sterilized, bagged, and pre-cooled to 4°C. They were then boxed and stacked in a cold storage. Randomly sampled from the bag were n0 bags with no surface damage or bulging.

[0069] S2. Magnetic field storage and preservation: The cold storage uses a periodic pulsed weak magnetic field with a magnetic field strength of 3mT, a frequency of 10Hz, a duty cycle of 0.4, and a ratio of the intermittent time of the magnetic field in each cycle of 1:2.5. The low temperature environment temperature is 4°C, the relative humidity is 65%, and the storage and preservation period is 30 days. The number of swollen bags n1 of the sampled n0 bags is measured. When the volume of the yogurt bag expands by more than 5%, it is considered to be swollen.

[0070] After the end, observe the changes in the bag swelling rate of yogurt storage, bag swelling rate = (n0-n1) / n0×100%, sample 1000 bags of yogurt, and no bag swelling.

[0071] Comparative Example 2: Effects of different storage conditions on yogurt preservation

[0072] Solution 1: Using the same raw materials and pretreatment as in Example 4, the yogurt was stored in a cold storage at 4°C and 65% relative humidity for 30 days. After storage, 1,000 bags of yogurt were sampled, and the bag expansion rate was 0.5%.

[0073] Solution 2: Adjust the duty cycle of S2 to 0.15. Other conditions are the same as those in Example 4.

[0074] Solution 3: Adjust the duty cycle of S2 to 0.85. Other conditions are the same as those in Example 4.

[0075] Solution 4: The ratio of the intermittent time of the magnetic field in each cycle of S2 is adjusted to 1:1. Other conditions are the same as those in Example 4.

[0076] Solution 5: Adjust the ratio of the magnetic field interval time in each cycle of S2 to 1:6. Other conditions are the same as those in Example 4.

[0077] Solution 6: Adjust the pulsed weak magnetic field in S2 to a steady weak magnetic field, specifically adjusting the magnetic field intensity to 15 mT. Other conditions are consistent with those in Example 4.

[0078] The effects of different storage conditions on the freshness of yogurt were compared, and the changes in the bag swelling rate of yogurt during storage were observed with reference to the sampling method of Example 4. The results are shown in Table 2.

[0079] Table 2 Preservation effect of yogurt under different storage conditions

[0080] Bag expansion rate Solution 1 0.5％ Option 2 0.2％ Option 3 0.3％ Option 4 0.1％ Option 5 0.2％ Option 6 0.1％

[0081] As shown in Table 2, excessively high or low magnetic field intensity, duty cycle, and intermittent period can affect yogurt preservation. Yogurt requires sterilization before storage, but sterilization time and temperature can affect yogurt flavor. Therefore, despite commercial sterility, a large number of lactic acid bacteria and other microorganisms remain in yogurt. Affected by the storage environment, some microorganisms in the yogurt grow, producing acid and gas, leading to bag bulging. The magnetic field environment affects protein synthesis, transmembrane ion transport, and biological genetics, inhibiting microbial metabolic activity. This effectively reduces microbial growth during storage and minimizes bag bulging. However, when magnetic field parameters are too high or too low, the inhibitory effect on microbial metabolic activity is less effective. Sugars and proteins in the yogurt act as carbon and nitrogen sources, promoting microbial growth, producing acid and gas, and leading to bag bulging. Yogurt costs approximately 3 yuan per bag. With a 5-ton storage capacity, approximately 25,000 bags of yogurt, the solution in Example 4 can directly save at least 75 to 375 yuan by avoiding bag bulging. Furthermore, if bag bulging occurs, the entire batch of products must be sampled and re-inspected, significantly increasing labor costs.

[0082] The above embodiment is merely one embodiment of the present invention, and its description is relatively specific and detailed, but it should not be construed as limiting the scope of the present invention. It should be noted that a person of ordinary skill in the art may make various modifications and improvements without departing from the scope of the present invention, and these modifications and improvements fall within the scope of protection of the present invention. Therefore, the scope of protection of the present invention shall be based on the appended claims.

Claims

1. A storage and preservation method for reducing the swelling rate of yogurt bags, characterized in that: The steps include: (1) Sterilize the yogurt, pack it in bags, and then pre-cool it to a temperature below 4°C. Then pack it in boxes and stack it in a cold storage; (2) Magnetic field storage and preservation: The cold storage adopts a periodic pulse weak magnetic field with a magnetic field intensity of 3mT, a frequency of 10~800 Hz, a duty cycle of 0.4, and a ratio of the magnetic field interval time in each cycle of 1:2.

5. The low temperature environment temperature is 4℃, the relative humidity is 65%, and the storage and preservation are carried out.