A kind of magnetic field low temperature sterilization technology of wild papaya enzyme and its application

Abstract

This invention discloses a magnetic field low-temperature sterilization technology for wild papaya enzyme and its application, belonging to the field of non-thermal food sterilization technology. This invention uses fermented wild papaya enzyme stock solution / concentrate as raw material, employing a high-intensity alternating magnetic field coupled with low-temperature synergistic sterilization. Treatment is carried out at 20-40℃, 0.4-1.0T, and 1.0-3.0kHz for 60-120 seconds, combined with pre-cooling, fine filtration, rapid cooling, and aseptic filling, achieving efficient sterilization while maximizing the preservation of SOD activity, natural flavor, and nutrients. This invention solves the problems of activity loss and flavor deterioration caused by traditional heat sterilization, and has advantages such as low-temperature preservation, uniform sterilization, continuous industrialization, no chemical residues, and traceability. The resulting product meets microbial indicators and has an SOD activity ≥1000U / mL, suitable for the industrial production of heat-sensitive fruit and vegetable enzyme beverages such as wild papaya enzyme and prickly pear enzyme.

Description

Technical Field

[0001] This invention belongs to the field of non-thermal sterilization technology for fruits and vegetables, specifically relating to a low-temperature magnetic field sterilization technology for wild papaya enzymes and its application. Background Technology

[0002] Wild papaya, a unique medicinal and edible fruit from Zheng'an County, Guizhou Province, is rich in polyphenols, flavonoids, organic acids, and superoxide dismutase (SOD), among other active substances. Wild papaya enzyme, produced through microbial fermentation, combines nutritional value with flavor characteristics, showing broad application prospects in functional beverages and health foods. However, many of the active ingredients in enzymes are heat-sensitive, easily undergoing degradation, polymerization, and oxidation under high temperatures. This leads to SOD inactivation, aroma loss, browning, and flavor deterioration. Therefore, low-temperature, non-thermal, and highly efficient sterilization technology has become a core bottleneck in the industrial production of wild papaya enzyme. Currently, the food industry primarily uses heat sterilization methods, including pasteurization and ultra-high temperature (UHT) sterilization. Traditional pasteurization typically requires temperatures above 65°C for several tens of minutes. While this achieves microbial control, it significantly damages heat-sensitive nutrients and functional components, resulting in SOD activity retention of less than 50%. This leads to weakened fruit aroma, darker color, and a poorer taste, failing to meet the quality and activity requirements of high-end enzyme beverages. Although ultra-high temperature instantaneous sterilization shortens the time, it still requires temperatures above 90°C, which still significantly damages the flavor and activity of the enzyme system and easily causes protein denaturation and precipitation, affecting product clarity and stability.

[0003] To address the shortcomings of thermal sterilization, the industry has gradually explored non-thermal technologies such as ultraviolet (UV) sterilization, ozone sterilization, high-voltage pulsed electric fields, and ultra-high-voltage sterilization. However, UV sterilization suffers from weak penetration, resulting in uneven sterilization of high-viscosity, high-color enzyme solutions and the creation of sterilization dead zones. Ozone sterilization easily introduces oxidation byproducts, damaging natural aromas and active substances. Ultra-high-voltage sterilization equipment requires significant investment, consumes a lot of energy, and has limited processing capacity, making it difficult to adapt to continuous production lines. While high-voltage pulsed electric fields offer high sterilization efficiency, they have strict requirements on the conductivity of the materials; wild papaya enzymes, with their high acidity and complex composition, suffer from insufficient sterilization stability. All of these non-thermal technologies suffer from incomplete sterilization, insufficient activity retention, high equipment costs, and difficulty in industrial-scale continuous production, failing to simultaneously meet the comprehensive demands of safe sterilization, high activity retention, intact flavor, and low-cost mass production. Magnetic field low-temperature sterilization, as a novel non-thermal physical sterilization technology, relies on the electro- and magnetostrictive effects generated by a high-intensity alternating magnetic field. This can disrupt the cell membrane structure and physiological functions of microorganisms under low-temperature conditions, achieving microbial inactivation. The processing temperature is typically controlled between 30–50℃, making it friendly to heat-sensitive components. However, existing magnetic field sterilization technologies are mostly applied to systems such as water, fruit juice, and dairy products. Specific process parameters, control methods, supporting procedures, and quality standards for wild papaya enzymes are lacking. Wild papaya enzymes have a slightly acidic pH and contain organic acids, pectin degradation products, and fermentation metabolites. Their physicochemical properties differ significantly from ordinary fruit and vegetable juices. Directly applying existing magnetic field parameters can easily lead to insufficient or excessive sterilization, loss of activity, and flavor fluctuations. Furthermore, traditional processes lack integrated designs for pre-cooling, fine filtration, rapid cooling, and aseptic filling, making it difficult to ensure that the sterilized product is not subject to secondary contamination and hindering automated monitoring and data traceability of key parameters.

[0004] Therefore, developing a low-temperature, high-efficiency, and continuously industrialized magnetic field low-temperature sterilization method adapted to the characteristics of wild papaya enzymes has become a pressing technical problem for the industry. This invention addresses the pain points in wild papaya enzyme production by optimizing core parameters such as magnetic field strength, frequency, temperature, and residence time. Through an integrated process of fine filtration, pre-cooling, magnetic field sterilization, rapid cooling, and aseptic filling, it achieves a balance between sterilization safety and activity preservation, filling the gap in non-thermal sterilization technology specifically for wild papaya enzymes and enhancing product quality and market competitiveness. Summary of the Invention

[0005] This invention addresses the problems of heat sterilization of wild papaya enzymes leading to loss of activity and deterioration of flavor, as well as the difficulty in industrializing existing non-heat sterilization methods. It provides a magnetic field low-temperature sterilization method that efficiently sterilizes at low temperatures while preserving SOD and flavor, enabling continuous and intelligent production, and obtaining safe, highly active, and high-quality wild papaya enzyme products.

[0006] To achieve the above objectives, the present invention provides the following technical solution: a method for low-temperature magnetic field sterilization of wild papaya enzyme, comprising, in sequence: raw material acceptance, fine filtration, pre-cooling, low-temperature magnetic field sterilization, cooling, and aseptic filling; wherein the low-temperature magnetic field sterilization adopts a high-intensity alternating magnetic field with a magnetic field strength of 0.4-1.0T, a magnetic field frequency of 1.0-3.0kHz, a processing temperature controlled at 20-40℃, and a material residence time in the sterilization zone of 60-120s.

[0007] The raw material is fermented and filtered wild papaya enzyme stock solution or concentrated solution, with the following initial indicators: pH 3.0-4.0, soluble solids ≥3%, and total bacterial count ≤1000 CFU / mL.

[0008] The fine filtration uses a 100-200 mesh sieve to remove fine fruit pulp fibers and sediment, making the material entering the sterilization system clear and transparent.

[0009] The precooling process involves reducing the enzyme solution to 20–40°C using a plate heat exchanger, which works in conjunction with the magnetic field to protect the heat-sensitive active ingredients.

[0010] The material flows continuously in a thin layer through a food-grade non-metallic insulated channel, allowing the magnetic field to act uniformly and without shielding on the material to complete sterilization.

[0011] After sterilization, the sample is rapidly cooled to below 4°C using a plate heat exchanger and then transferred to a pre-sterilized aseptic temporary storage tank.

[0012] The sterilization process is monitored in real time by a PLC control system, which monitors the magnetic field strength, flow rate, and temperature. If the parameters exceed the limits, an alarm will be triggered and the machine will be shut down automatically. The system also has the function of recording and tracing operating data.

[0013] The magnetic field low-temperature sterilization system of the method includes a magnetic field generating device, a pre-cooling unit, a cooling unit, a stepless speed-regulating material conveying system, an aseptic filling unit, and a PLC intelligent control unit.

[0014] The application of the sterilization method described above in the sterilization and processing of wild papaya enzyme stock solution, wild papaya enzyme concentrate, and compound fruit and vegetable enzyme beverage.

[0015] A specific step of the sterilization method includes the following steps: A. Pretreatment: Take the fermented and filtered wild papaya enzyme concentrate and test it to confirm: pH 3.0–4.0, soluble solids ≥12%, initial total bacterial count ≤1000 CFU / mL; then, use a 200-mesh sieve for precision filtration to remove fine fruit pulp fibers, colloids and precipitates from the concentrate, ensuring the liquid is clear and transparent, avoiding blockage of the flow channel and affecting the uniformity of the magnetic field; further, pump the finely filtered concentrate into a pre-cooling tank and cool it to 28–30℃ through a plate heat exchanger to prepare for low-temperature magnetic field sterilization and protect the heat-sensitive active ingredients; B. Low-temperature sterilization with magnetic field: Start the magnetic field sterilization system and set the core parameters: magnetic field strength: 0.9T; magnetic field frequency: 2.5kHz; processing temperature: 28℃; material residence time: 110s; the material flows continuously in a thin layer through the food-grade non-metallic insulated flow channel and is sterilized under the action of a high-intensity alternating magnetic field. C. Sterilization and Aseptic Treatment: Immediately after sterilization, the mixture is rapidly cooled to below 2°C using a plate heat exchanger and transferred to a pre-sterilized aseptic temporary storage tank to prevent activity decay and secondary contamination. Then, it is filled and sealed using an aseptic filling line in a clean workshop. The packaging materials are sterilized in advance to avoid contamination throughout the process, resulting in the final wild papaya enzyme concentrate product. Finally, the product is inspected for microbial activity, SOD activity, sensory properties, and physicochemical indicators before being put into storage. If it passes the inspection, it is stored at low temperature.

[0016] Compared with the prior art, the present invention has the following outstanding features: (1) The present invention uses low temperature 20–40℃ synergistic alternating magnetic field sterilization to avoid the degradation of heat-sensitive components such as wild papaya enzyme SOD, fruit aroma, and organic acids caused by high temperature. The SOD activity retention rate is ≥90%, and the product flavor, color and nutrition are completely preserved.

[0017] (2) Magnetic field low-temperature sterilization is a non-thermal physical sterilization technology. Its core principle is to use a high-intensity alternating magnetic field at low temperature to produce biophysical effects on microorganisms, causing damage to their structure and physiological functions and thus inactivating them, while avoiding the destruction of heat-sensitive active substances by high temperature. In this invention, the material flows continuously through a food-grade non-metallic flow channel in a thin layer. A high-frequency pulsed current forms a high-intensity alternating magnetic field through a solenoid coil, which has three effects on microorganisms: electrical effect and membrane perforation. The alternating magnetic field induces instantaneous microcurrents in the microbial cells, causing cell membrane potential disturbances, destroying membrane permeability, leading to leakage of intracellular substances and cell death. Magnetostrictive effect. The magnetic field causes the cell wall and cell membrane of microorganisms to undergo periodic stretching and deformation, resulting in structural breakage and damage, making it unable to complete metabolism and reproduction. Biomolecular damage. The magnetic field interferes with the enzyme system, nucleic acid and protein structure in microorganisms, inhibiting life activities such as respiration and replication, achieving rapid and efficient inactivation. The entire process is completed under low temperature, non-heating, and no chemical additives conditions, which can meet the food sterilization safety requirements and retain the SOD activity, natural flavor, organic acids and nutrients in wild papaya enzymes to the maximum extent.

[0018] (3) An integrated continuous production line combining fine filtration, precooling, magnetic field sterilization, rapid cooling, and aseptic filling, coupled with PLC intelligent monitoring and data traceability, features a high degree of automation, stable operation, and easy cleaning and maintenance, meeting the needs of large-scale mass production. It destroys the cell membrane structure of microorganisms through a 0.4–1.0T high-intensity alternating magnetic field, ensuring thorough sterilization without dead corners. Key indicators such as total bacterial count, coliform bacteria, and mold and yeast all meet beverage safety standards, with no chemical residues and no radiation risks. The four-dimensional parameter combination of magnetic field strength, frequency, temperature, and residence time can be adapted to wild papaya enzyme stock solution, concentrated solution, and compound enzyme, ensuring uniform sterilization and high batch consistency, solving the problem of unstable sterilization in high-acid and high-viscosity systems. Specific Implementation

[0019] The present invention will be further described in detail below with reference to specific embodiments, but the scope of protection of the present invention is not limited to the following embodiments. Unless otherwise specified, the methods used in the following embodiments are conventional methods. Example 1

[0020] A method for low-temperature magnetic field sterilization of wild papaya enzyme includes, in sequence: raw material acceptance, fine filtration, pre-cooling, low-temperature magnetic field sterilization, cooling, and aseptic filling; the low-temperature magnetic field sterilization adopts a high-intensity alternating magnetic field with a magnetic field strength of 0.4-1.0T, a magnetic field frequency of 1.0-3.0kHz, a processing temperature controlled at 20-40℃, and a material residence time in the sterilization zone of 60-120s.

[0021] The raw material is fermented and filtered wild papaya enzyme stock solution or concentrated solution, with the following initial indicators: pH 3.0-4.0, soluble solids ≥3%, and total bacterial count ≤1000 CFU / mL.

[0022] The fine filtration uses a 100-200 mesh sieve to remove fine fruit pulp fibers and sediment, making the material entering the sterilization system clear and transparent.

[0023] The precooling process involves reducing the enzyme solution to 20–40°C using a plate heat exchanger, which works in conjunction with the magnetic field to protect the heat-sensitive active ingredients.

[0024] The material flows continuously in a thin layer through a food-grade non-metallic insulated channel, allowing the magnetic field to act uniformly and without shielding, thus completing the sterilization process. After sterilization, it is rapidly cooled to below 4°C via a plate heat exchanger and then transferred to a pre-sterilized aseptic storage tank. The sterilization process is monitored in real time by a PLC control system, which monitors the magnetic field strength, flow rate, and temperature. The system automatically alarms and shuts down when parameters exceed limits, and also features operational data recording and traceability functions.

[0025] A magnetic field low-temperature sterilization system is characterized by comprising a magnetic field generating device, a pre-cooling unit, a cooling unit, a stepless speed-regulating material conveying system, an aseptic filling unit, and a PLC intelligent control unit.

[0026] The application of the sterilization method described above in the sterilization and processing of wild papaya enzyme stock solution, wild papaya enzyme concentrate, and compound fruit and vegetable enzyme beverage.

[0027] A specific step of the sterilization method includes the following steps: A. Pretreatment: Take the fermented and filtered wild papaya enzyme concentrate and test it to confirm: pH 3.0–4.0, soluble solids ≥12%, initial total bacterial count ≤1000 CFU / mL; then, use a 200-mesh sieve for precision filtration to remove fine fruit pulp fibers, colloids and precipitates from the concentrate, ensuring the liquid is clear and transparent, avoiding blockage of the flow channel and affecting the uniformity of the magnetic field; further, pump the finely filtered concentrate into a pre-cooling tank and cool it to 28–30℃ through a plate heat exchanger to prepare for low-temperature magnetic field sterilization and protect the heat-sensitive active ingredients; B. Low-temperature sterilization with magnetic field: Start the magnetic field sterilization system and set the core parameters: magnetic field strength: 0.9T; magnetic field frequency: 2.5kHz; processing temperature: 28℃; material residence time: 110s; the material flows continuously in a thin layer through the food-grade non-metallic insulated flow channel and is sterilized under the action of a high-intensity alternating magnetic field. C. Sterilization and Aseptic Treatment: Immediately after sterilization, the mixture is rapidly cooled to below 2°C using a plate heat exchanger and transferred to a pre-sterilized aseptic temporary storage tank to prevent activity decay and secondary contamination. Then, it is filled and sealed using an aseptic filling line in a clean workshop. The packaging materials are sterilized in advance to avoid contamination throughout the process, resulting in the final wild papaya enzyme concentrate product. Finally, the product is inspected for microbial activity, SOD activity, sensory properties, and physicochemical indicators before being put into storage. If it passes the inspection, it is stored at low temperature. Example 2

[0028] Low-temperature sterilization of wild papaya enzyme stock solution using magnetic field: Fermented wild papaya enzyme stock solution was tested and found to have the following characteristics: pH 3.6, soluble solids 4.2%, initial total bacterial count 680 CFU / mL, and no coliform bacteria or pathogenic bacteria detected. The solution was then finely filtered through a 150-mesh sieve to remove fine fibers and sediment; pre-cooled to 30°C using a plate heat exchanger; and sterilized using a low-temperature magnetic field with the following parameters: magnetic field strength 0.7T, magnetic field frequency 2.0kHz, processing temperature 30°C, and material residence time 90s. After sterilization, the solution was rapidly cooled to 3°C and transferred to a sterile temporary storage tank for aseptic filling and sealing in a cleanroom.

[0029] Factory inspection results: The total bacterial count of the finished product was 42 CFU / mL, and no coliform bacteria, mold, yeast, or pathogenic bacteria were detected; the SOD activity was 1460 U / mL, with a retention rate of 93%; the product was dark amber in color, clear and transparent, with a rich fruity aroma, no browning, and no off-odor, meeting the standards for wild papaya enzyme products. Example 3

[0030] Wild papaya enzyme concentrate was sterilized under low-temperature magnetic field: Wild papaya enzyme concentrate was tested and found to have: soluble solids 12.5%, pH 3.4, initial total bacterial count 920 CFU / mL, and SOD activity 4360 U / mL. It was then finely filtered through a 200-mesh sieve; pre-cooled to 28℃; magnetic field sterilization parameters: magnetic field strength 0.9T, frequency 2.5kHz, temperature 28℃, residence time 110s; after sterilization, it was rapidly cooled to 2℃.

[0031] Factory inspection results: total bacterial count 28 CFU / mL, no coliform bacteria detected, mold and yeast both <5 CFU / mL; SOD activity 4054.8 U / mL, retention rate 93%; the product is clear without precipitation or layering, has a stable flavor, and is suitable for processing high-concentration enzyme products. Example 4

[0032] Wild papaya-prickly pear compound enzyme beverage sterilized at low temperature using magnetic field: Wild papaya enzyme concentrate and prickly pear juice are blended in a specific ratio to create a compound enzyme beverage. It is then filtered through a 150-mesh sieve and pre-cooled to 32°C; sterilized at low temperature using a magnetic field: magnetic field strength 0.6T, frequency 1.8kHz, temperature 32°C, residence time 80s; after sterilization, it is cooled to 3°C and aseptically filled.

[0033] Factory inspection results: Microbiological indicators are qualified; SOD retention rate is 92%; the product is light amber in color, has a fresh fruity aroma, a harmonious taste, no off-odors from heat processing, and can be stored in the dark for up to 9 months.

[0034] To further verify the beneficial effects of the sterilization method described in this invention, it was compared with pasteurization and ultra-high temperature (UHT) sterilization. The same batch of wild papaya enzyme concentrate as in Example 3 was used, with the same initial state of the raw materials: pH 3.4, soluble solids 12.5%, and initial total bacterial count 920 CFU / mL. Traditional pasteurization and ultra-high temperature (UHT) sterilization were used respectively, while the remaining raw materials, filling, storage, and testing conditions were exactly the same as those of the magnetic field low-temperature sterilization group of this invention. The results are shown in Table 1. Table 1 Comparison of sterilization effects of different sterilization methods

[0035]

[0036] In summary, while traditional pasteurization and ultra-high temperature instantaneous sterilization can inactivate microorganisms, high temperatures severely damage the heat-sensitive functional components in wild papaya enzyme concentrate: the SOD activity retention rate after pasteurization is less than 50%; high-temperature sterilization leads to browning and aroma loss. The magnetic field low-temperature sterilization technology of this invention completes sterilization at 20–40℃, without heating or chemical residue, achieving an SOD retention rate of ≥90%. Its color, aroma, clarity, and stability are significantly superior to heat sterilization, making it more suitable for the high-quality, high-activity industrial production of wild papaya enzyme concentrate. The above description is merely a preferred embodiment of the present invention and does not constitute any limitation on the invention. Any simple modifications, equivalent changes, or alterations made to the above embodiments based on the technical essence of the present invention without departing from the scope of the invention are still within the scope of the present invention.

Claims

1. A method for low-temperature sterilization of wild papaya enzyme using a magnetic field, characterized in that, In order, they include: Raw material acceptance, fine filtration, pre-cooling, magnetic field low-temperature sterilization, cooling, and aseptic filling; the magnetic field low-temperature sterilization adopts a high-intensity alternating magnetic field with a magnetic field strength of 0.4-1.0T, a magnetic field frequency of 1.0-3.0kHz, a processing temperature controlled at 20-40℃, and a material residence time in the sterilization zone of 60-120s.

2. The method for low-temperature sterilization of wild papaya enzyme using a magnetic field according to claim 1, characterized in that, The raw material is fermented and filtered wild papaya enzyme stock solution or concentrated solution, with the following initial indicators: pH 3.0-4.0, soluble solids ≥3%, and total bacterial count ≤1000 CFU / mL.

3. The sterilization method according to claim 1, characterized in that, The fine filtration uses a 100-200 mesh sieve to remove fine fruit pulp fibers and sediment, making the material entering the sterilization system clear and transparent.

4. The sterilization method according to claim 1, characterized in that, The precooling process involves reducing the enzyme solution to 20–40°C using a plate heat exchanger, which works in conjunction with the magnetic field to protect the heat-sensitive active ingredients.

5. The sterilization method according to claim 1, characterized in that, The material flows continuously in a thin layer through a food-grade non-metallic insulated channel, allowing the magnetic field to act uniformly and without shielding on the material to complete sterilization.

6. The sterilization method according to claim 1, characterized in that, After sterilization, the sample is rapidly cooled to below 4°C using a plate heat exchanger and then transferred to a pre-sterilized aseptic temporary storage tank.

7. The sterilization method according to claim 1, characterized in that, The sterilization process is monitored in real time by a PLC control system, which monitors the magnetic field strength, flow rate, and temperature. If the parameters exceed the limits, an alarm will be triggered and the machine will be shut down automatically. The system also has the function of recording and tracing operating data.

8. A magnetic field low-temperature sterilization system for use in the method of any one of claims 1-7, characterized in that, It includes a magnetic field generator, a pre-cooling unit, a cooling unit, a stepless speed-regulating material conveying system, an aseptic filling unit, and a PLC intelligent control unit.

9. The application of the sterilization method as described in any one of claims 1-7 in the sterilization and processing of wild papaya enzyme stock solution, wild papaya enzyme concentrate, and compound fruit and vegetable enzyme beverage.

10. A specific step of the sterilization method as described in any one of claims 1-7: characterized in that, Includes the following steps: A. Pretreatment: Take the fermented and filtered wild papaya enzyme concentrate and test it to confirm: pH 3.0–4.0, soluble solids ≥12%, initial total bacterial count ≤1000 CFU / mL; then, use a 200-mesh sieve for precision filtration to remove fine fruit pulp fibers, colloids and precipitates from the concentrate, ensuring the liquid is clear and transparent, avoiding blockage of the flow channel and affecting the uniformity of the magnetic field; further, pump the finely filtered concentrate into a pre-cooling tank and cool it to 28–30℃ through a plate heat exchanger to prepare for low-temperature magnetic field sterilization and protect the heat-sensitive active ingredients; B. Low-temperature sterilization using magnetic field: Activate the magnetic field sterilization system and set the core parameters: Magnetic field strength: 0.9T; Magnetic field... Frequency: 2.5kHz; Processing temperature: 28℃; Material residence time: 110s; The material flows continuously in a thin layer through a food-grade non-metallic insulated flow channel and is sterilized under the action of a high-intensity alternating magnetic field. C. Sterilization and Aseptic Treatment: Immediately after sterilization, the mixture is rapidly cooled to below 2°C using a plate heat exchanger and transferred to a pre-sterilized aseptic temporary storage tank to prevent activity decay and secondary contamination. Then, it is filled and sealed using an aseptic filling line in a clean workshop. The packaging materials are sterilized in advance to avoid contamination throughout the process, resulting in the final wild papaya enzyme concentrate product. Finally, the product is inspected for microbial activity, SOD activity, sensory properties, and physicochemical indicators before being put into storage. If it passes the inspection, it is stored at low temperature.

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