A preparation device for low-temperature plasma-activated water and a method for removing pesticide residues from versicolor powder

Abstract

The present invention provides a plasma treatment method and equipment for removing pesticide residues in Yunzhi fungus powder. The present invention is combined with a pulse power supply by a dielectric barrier discharge plasma generator, connected to a water treatment reactor, and a 304 stainless steel gasket is added to help introduce an electric field and shorten the discharge distance, thereby increasing energy. The plasma activated water treatment reaction conditions are optimized, and the plasma activated water after analysis and treatment is used to analyze the degradation effect of chlorpyrifos and acetochlor pesticides in Yunzhi fungus powder, and the effect of the treatment on the content of β-glucan in Yunzhi fungus powder is detected. It is proved that the method has a good agricultural residue degradation effect. The present invention adopts a water treatment reactor with a 304 stainless steel gasket having a thickness of 2 to 3 mm, and plasma activated water is made after being treated by a pulse power supply dielectric barrier discharge plasma. Yunzhi fungus powder with chlorpyrifos and acetochlor residues is soaked. After soaking, the chlorpyrifos content decreases by 91.7%, and the acetochlor content decreases by 90.1%.

Description

Technical Field

[0001] The invention belongs to the technical field of removing pesticide residues from edible agricultural products, and particularly relates to a device for preparing low-temperature plasma-activated water and a method for removing pesticide residues from versicolor fungus powder. Background Art

[0002] Food is the primary need of the people. Food safety has always been an issue of close concern to consumers. Therefore, when cleaning agricultural products, special attention should be paid to the treatment of residual pesticides to avoid excessive pesticide residues and improve the quality of agricultural products in order to gain a wider market.

[0003] Traditional heat treatment can affect the nutritional and properties of pesticide residues while removing them, so non-thermal pesticide residue removal technologies have become a research focus in recent years. Currently, physical methods for degrading pesticide residues include acidified water, adsorption, ultrasound, irradiation, high pressure, pulse, and low-temperature plasma. These methods overcome the shortcomings and deficiencies of traditional heat treatment and have important theoretical significance and practical application value in the rapid and efficient degradation of pesticide residues in fruits and vegetables. Low-temperature plasma treatment produces abundant active substances with excellent oxidative capacity, demonstrating unique advantages in the field of food sterilization and disinfection, effectively degrading a variety of inorganic and organic substances.

[0004] In the existing low-temperature plasma treatment technology, the surface is treated by low-temperature plasma airflow, and the effect of treating residual pesticides is not very high. For example, the Chinese invention patent application document with application number CN202111124736.6 discloses a pretreatment technology for edible fungi before processing, including cutting and screening, air drying, two-step plasma airflow treatment, and plasma water treatment. This technical solution achieves sterilization, preservation, metabolism inhibition and degradation of residual pesticides of edible fungi through the first step of plasma airflow treatment. The production operation of this method is complicated, and the detection amount of residual pesticides in the final food produced is still very high, which cannot meet export requirements. Summary of the Invention

[0005] To address the above technical issues, the present invention provides a device for producing low-temperature plasma-activated water and a method for removing pesticide residues from versicolor fungus powder. This invention incorporates a stainless steel gasket in the plasma water generator to introduce an electric field. This significantly improves the pesticide residue removal rate.

[0006] The specific technical solutions of the present invention are as follows:

[0007] A low-temperature plasma-activated water preparation device comprises a pulse modulator, a voltage regulator and a plasma-activated water generating device electrically connected in sequence. The plasma-activated water generating device comprises a positive electrode and a negative electrode arranged opposite to each other, and an activated water generating container arranged between the positive electrode and the negative electrode for containing water. The activated water generating container is made of quartz and is provided with a stainless steel gasket for introducing an electric field.

[0008] In the prior art, devices for preparing plasma-activated water typically employ dielectric barrier discharge. However, the plasma or plasma-activated water produced by this method still suffers from poor pesticide residue removal when used to remove impurities from edible fungi. For example, in the aforementioned technical solution of sterilizing and disinfecting edible fungi and degrading pesticide residues through plasma airflow flushing, the plasma-activated water used is not sufficiently effective in removing pesticide residues from edible fungi.

[0009] In the above-mentioned technical solution of the present application, by setting a stainless steel gasket in the device for preparing plasma-activated water, the low-temperature plasma water produced by the device has a good effect of removing pesticide residues on the surface of edible fungi, while having a relatively small impact on the effective ingredients of Yunzhi powder; among them, the low-temperature plasma-activated water prepared by the preparation device has a degradation rate of 91.7% for chlorpyrifos and a degradation rate of 90.1% for acetochlor. After treatment, the β-glucan content in Yunzhi powder only decreased by 9.52%.

[0010] As a preferred embodiment of the above technical solution of the present application, the thickness of the stainless steel gasket is 2~3mm.

[0011] Another object of the present application is to provide a method for removing pesticide residues in versicolor powder, comprising the following steps:

[0012] S1. Preparation of low-temperature plasma-activated water: preparing low-temperature plasma-activated water using the above-mentioned low-temperature plasma-activated water preparation device;

[0013] S2. Add the crushed and homogenized versicolor powder to the plasma-activated water in step S1, and stir, filter, and dry to obtain the versicolor powder without pesticide residues.

[0014] In the above technology of the present application, the pesticide residues on the surface of the versicolor powder are removed by soaking the versicolor powder in the low-temperature plasma activated water prepared by the low-temperature plasma activated water preparation device, and the effect of removing the pesticide residues is good. At the same time, the effect on the effective components inside the versicolor powder is not significant. The loss of the beneficial substances in this part is mainly the dissolution loss of the effective substances dissolved in the water body during the soaking process.

[0015] As a preferred embodiment of the above technical solution of the present application, in step S1, the voltage for preparing the low-temperature plasma activated water is 90~220V and the frequency is 200~1000Hz.

[0016] As a preferred embodiment of the above technical solution of the present application, in step S1, the discharge distance is 8 to 20 mm, and the processing time is 60 to 120 s.

[0017] As a preferred embodiment of the above technical solution of the present application, the method further includes S3, detecting the pesticide-removed versicolor powder: extracting and concentrating the pesticide-removed versicolor powder to obtain an extract, and performing gas chromatography-mass spectrometry detection on the extract.

[0018] As a preferred embodiment of the above technical solution of the present application, in step 2, the time for soaking the versicolor powder in low-temperature plasma-activated water is at least 30 minutes.

[0019] By adopting the method of the present invention, the removal rate of chlorpyrifos in the versicolor fungus powder is greater than 80%, and the removal rate of acetochlor in the versicolor fungus powder is greater than 80%.

[0020] Step S2 also includes testing the pesticide-residue-removed versicolor powder. Testing the fruits and vegetables includes the following steps: extracting, concentrating, and performing GC-MS analysis on the pesticide-residue-removed fruits and vegetables. The initial chlorpyrifos content in the versicolor powder was 0.060 mg / kg, and the initial acetochlor content was 0.882 mg / kg. After treatment, the chlorpyrifos content in the versicolor powder was 0.005 mg / kg, and the acetochlor content was 0.087 mg / kg. The low-temperature plasma-activated water had a degradation rate of 91.7% for chlorpyrifos and 90.1% for acetochlor. Determination showed that the β-glucan content in the versicolor powder decreased by 9.52% after treatment.

[0021] In summary, the beneficial effects of the present invention are as follows:

[0022] 1. The present invention improves plasma activated water treatment by adding a stainless steel gasket to a device for preparing low-temperature plasma water;

[0023] 2. A supplementary pipe and a drain pipe for inputting or discharging water are set in the plasma water generating device, which facilitates the continuous production of plasma activated water;

[0024] 3. The pesticide residue removal method provided by the present invention has a good pesticide residue removal effect, and the pesticide residue removal rate can reach 97.4%. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 A low-temperature plasma activated water preparation device provided in the present invention;

[0026] Figure 2 This is an enlarged detail view of the activated water generating container 33 used in this experiment, wherein 34 is the stacked 304 stainless steel gaskets;

[0027] In the figure, 1-pulse modulator, 2-voltage regulator, 3-plasma activated water generating device, 31-positive electrode, 32-negative electrode, 33-activated water generating container, 34-stainless steel gasket. DETAILED DESCRIPTION

[0028] The following describes the embodiments of the present invention through specific examples. Those skilled in the art will readily understand the other advantages and benefits of the present invention from the disclosure herein. The present invention may also be implemented or applied through various other specific embodiments, and the details in this specification may be modified or altered based on different viewpoints and applications without departing from the spirit of the present invention.

[0029] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings in the embodiments of the present invention. The embodiments are only used to explain the present invention and do not limit the scope of protection of the present invention. Example

[0030] like Figure 1 and Figure 2 A low-temperature plasma-activated water preparation device includes a pulse modulator 1, a voltage regulator 2, and a plasma-activated water generator 3 electrically connected in sequence. The plasma-activated water generator 3 includes a positive electrode 31 and a negative electrode 32 arranged opposite each other, and an activated water generating container 33 for containing water arranged between the positive electrode 31 and the negative electrode 32. A stainless steel gasket 34 for introducing an electric field is arranged in the activated water generating container 33; the thickness of the stainless steel gasket 34 is 2 to 3 mm.

[0031] Preparation of plasma activated water: Pour a certain amount of tap water into the activated water generating container 33, with the liquid surface thickness in the container being 5 mm and the discharge distance being 20 mm → Place the activated water generating container 33 between the positive electrode 31 and the negative electrode 32 → Turn on the power → Turn on the pulse modulator 1 and adjust the instrument pulse modulator 1 so that the discharge frequency is 500 Hz and the pulse duty cycle is 50% → Adjust the voltage regulator 2 so that the test power supply main unit voltage displays 90 V → Process in this state for 90 s → Transfer the treated activated water to a beaker for later use.

[0032] Sample processing: Place 5 g of Coriolus versicolor powder in a beaker → Pour in low-temperature plasma-activated water → Stir the powder to ensure full contact with the activated water → Soak for 30 minutes → Centrifuge at 6000 rpm at 4°C for 5 minutes to remove the supernatant → Sample extraction and determination.

[0033] Sample extraction and concentration: Add 8 mL of acetonitrile to the above centrifuge tube → Vortex and mix → Add 2 tablespoons of sodium chloride and sonicate in a centrifuge tube ultrasonic cleaner for 20 min → Centrifuge at 4000 rpm for 3 min → Use a pipette to transfer 4 mL of supernatant to a 15 mL centrifuge tube → Set the nitrogen blowdown temperature to 60°C and adjust the gas flow rate to blow the sample to near dryness → Add 2 mL of acetonitrile and Vortex and mix → Pass the sample through a series of acetonitrile-rinsed NanoChrome C18 solid-phase extraction cartridges and NanoChrome silica-based solid-phase extraction cartridges → Collect in a 15 mL centrifuge tube → Repeat extraction once → Set the nitrogen blowdown temperature to 60°C and adjust the gas flow rate to blow the sample to near dryness → Add 1.5 mL of chromatography-grade n-hexane and Vortex and mix → Pass the solution through a 0.22 μm microporous organic filter membrane → Transfer to a 2 mL injection vial.

[0034] Detection of chlorpyrifos and acetochlor in samples: The above samples were injected and tested using a GCMS-TQ8040 NX triple quadrupole gas chromatograph-mass spectrometer, using an Rxi-5Sil MS column and an EI source. Quantification was performed using an external standard method. The chlorpyrifos and acetochlor concentrations in the samples (c) were determined in mg / L. The following formula was used to convert the chlorpyrifos and acetochlor residues (ρ) in the original Coriolus versicolor powder sample into mg / kg.

[0035] ρ=(C×V1×V2) / (M×V3);

[0036] Where: C is the concentration of chlorpyrifos and acetochlor in the sample obtained after quantification;

[0037] V1 - volume of n-hexane, take 1.5 mL;

[0038] V2 - acetonitrile extraction volume, 8 mL;

[0039] M ——mass of raw material sample of Yunzhi powder, 5 g;

[0040] V3 is the volume of supernatant after the second centrifugation, which is 4 mL.

[0041] Results: After extraction, purification, and GC-MS analysis, the initial chlorpyrifos content in the versicolor powder was 0.060 mg / kg, and the initial acetochlor content was 0.882 mg / kg. After treatment, the chlorpyrifos content in the versicolor powder was 0.012 mg / kg, and the acetochlor content was 0.156 mg / kg. The degradation rates of the low-temperature plasma-activated water for chlorpyrifos were 80.0%, and for acetochlor was 82.3%. Example

[0042] The difference between this embodiment and embodiment 1 is that when preparing plasma-activated water, a 304 stainless steel gasket is used in the reactor to adjust the discharge distance to 15 mm.

[0043] Results: After extraction, purification, and GC-MS analysis, the initial chlorpyrifos content in the versicolor powder was 0.060 mg / kg, and the initial acetochlor content was 0.882 mg / kg. After treatment, the chlorpyrifos content in the versicolor powder was 0.009 mg / kg, and the acetochlor content was 0.114 mg / kg. The degradation rates of the low-temperature plasma-activated water for chlorpyrifos were 85.0%, and for acetochlor was 87.1%. Example

[0044] The difference between this example and Example 1 is that when preparing plasma-activated water, a 304 stainless steel gasket is used in the reactor to adjust the discharge distance to 8 mm; after treatment and centrifugation, the β-glucan content in the sample is detected using a β-glucan detection kit produced by Megazyme, Ireland.

[0045] Determination of glucan content: Weigh 50 mg of treated sample into a culture tube → add 2 mL of 12 M concentrated sulfuric acid, cover, and vortex to mix → place in an ice-water bath for 2 h → add 4 mL of water, cover, and vortex for 10 s → add 6 mL of water, cover, and vortex for 10 s → loosen the cap and place the tube in a boiling water bath (100°C) for 5 min → tighten the cap and continue boiling for 2 h → cool to room temperature → transfer to a 100 mL volumetric flask, add 6 mL of 8.0 M NaOH solution, rinse the tube with 200 mM sodium acetate buffer (pH 4.41), make up to volume and mix → transfer 1.5 mL of the sample solution to a 2 mL sample tube and centrifuge at 13,000 rpm for 5 min in a high-speed refrigerated centrifuge → place 0.1 mL of the supernatant at the bottom of a clean, dry test tube and add 0.1 mL of 200 mM sodium acetate buffer (pH = Add 1,3-β-glucan exonuclease (20 U / mL) and β-glucosidase (4 U / mL) in 4.5) → Vortex to mix and incubate at 40°C for 1 hour → Add 3 mL of glucose oxidase / peroxidase reagent (GOPOD) → Prepare a control group and glucose standard (100 μg) in two separate tubes and incubate at 40°C for 20 minutes. → Measure the absorbance of Abs at 510 nm using a UV spectrophotometer and calculate the content (% w / w) using the following formula:

[0046] Total sugar content (% W / W) = ∆E × F × (100 / 0.1) × (1 / 1000) × (100 / W) × (162 / 180) = ∆E × F / W × 90;

[0047] α-glucan content (% W / W) = ∆E × F × 103 × (1 / 1000) × (100 / W) × (162 / 180) = ∆E × F / W × 9.27;

[0048] β-glucan content = total sugar content - α-glucan content;

[0049] Where W is the weight of the sample, which is 50 mg.

[0050] △E——Absorbance of the sample measured with the blank reagent control group as the benchmark;

[0051] F is the conversion coefficient between Abs absorbance and D-glucose mass μg, which is 100.

[0052] Results: After extraction, purification, and GC-MS analysis, the initial chlorpyrifos content in the versicolor powder was 0.060 mg / kg, and the initial acetochlor content was 0.882 mg / kg. After treatment, the chlorpyrifos content in the versicolor powder was reduced to 0.005 mg / kg, and the acetochlor content was 0.087 mg / kg. The low-temperature plasma-activated water had a degradation rate of 91.7% for chlorpyrifos and 90.1% for acetochlor. The β-glucan content in the versicolor powder decreased by 9.52% after treatment. Example

[0053] The difference between this embodiment and embodiment 1 is that the sample to be immersed is a standard solution of chlorpyrifos and acetochlor.

[0054] Results: After extraction, purification, and GC-MS analysis, the initial content of chlorpyrifos was 0.120 mg / kg, and the initial content of acetochlor was 1.200 mg / kg. After treatment, the content of chlorpyrifos was 0.009 mg / kg, and the content of acetochlor was 0.228 mg / kg. The degradation rate of chlorpyrifos and acetochlor by the low-temperature plasma-activated water reached 92.5%, and the degradation rate of acetochlor reached 85.8%.

[0055] Comparative Example 1:

[0056] The difference between this comparative example and Example 1 is that the powder sample is soaked in acidic oxidizing potential water.

[0057] Preparation of acidic oxidizing potential water: Use an acidic oxidizing potential water generator to add pure water and sufficient sodium chloride into a dedicated container to prepare acidic oxidizing potential water (main components are hypochlorous acid, chlorine, hydrochloric acid, active oxygen, active hydroxyl, hydrogen peroxide, etc., pH 2.0-3.0) and set aside.

[0058] Sample processing: Take 5 g of sample into a beaker → Pour in treated acidic oxidizing potential water → Stir the powder to make it fully contact with the acidified water → Soak for 5 minutes → Add 0.1M sodium thiosulfate solution to terminate the reaction → Ultrasonic cleaning instrument for 30 minutes → Centrifuge at 4℃, 6000 rpm for 5 minutes to remove the supernatant → Sample is extracted, purified, and measured.

[0059] Results: After extraction, purification, and GC-MS analysis, the initial chlorpyrifos content in the versicolor powder was 0.060 mg / kg, and the initial acetochlor content was 0.882 mg / kg. After treatment, the chlorpyrifos content in the versicolor powder was 0.015 mg / kg, and the acetochlor content was 0.219 mg / kg. The degradation rates of the acidic oxidizing potential water for chlorpyrifos were 75.0%, and for acetochlor were 75.2%.

[0060] Comparative Example 2:

[0061] The difference between this comparative example and Example 1 is that the chlorpyrifos and acetochlor standard solutions are treated with acidic oxidizing potential water.

[0062] Results: After extraction, purification, and GC-MS analysis, the initial chlorpyrifos content in the versicolor powder was 0.120 mg / kg, and the initial acetochlor content was 1.600 mg / kg. After treatment, the chlorpyrifos content in the versicolor powder was 0.053 mg / kg, and the acetochlor content was 0.522 mg / kg. The degradation rates of the acidic oxidizing potential water for chlorpyrifos were 55.8%, and for acetochlor was 67.4%.

[0063] Comparative Example 3:

[0064] The difference between this embodiment and embodiment 1 is that, when preparing plasma-activated water, glass balls with a diameter of 3 mm were used in the reactor to adjust the discharge distance to 8 mm.

[0065] Results: After extraction, purification, and GC-MS analysis, the initial chlorpyrifos content in the versicolor powder was 0.060 mg / kg, and the initial acetochlor content was 0.882 mg / kg. After treatment, the chlorpyrifos content in the versicolor powder was 0.018 mg / kg, and the acetochlor content was 0.184 mg / kg. The degradation rates of the low-temperature plasma-activated water for chlorpyrifos were 70.0%, and for acetochlor was 79.1%.

[0066] According to the comparison of Example 1, Example 2, Example 3 and Comparative Example 3, the degradation rate of pesticide residues in the versicolor powder treated with this method is the highest;

[0067] According to the comparison between Example 3 and Example 3, when the discharge distance is the same, the 304 stainless steel gasket can better introduce the electric field than the glass ball, thereby enhancing the degradation effect of pesticide residues;

[0068] According to the comparison between Example 2 and Example 3, appropriately shortening the low-temperature plasma discharge distance can enhance the degradation effect of pesticide residues;

[0069] According to the comparison between Example 3 and Example 4, the degradation efficiency of low-temperature plasma-activated water on the chlorpyrifos standard product is higher than that on the bacterial powder sample.

[0070] According to the comparison between Example 1, Example 2, and Example 3 and Comparative Example 1, it can be seen that for the bacterial powder sample, the treatment effect of low-temperature plasma activated water is better than that of acidic oxidizing potential water.

[0071] According to the comparison between Example 4 and Comparative Example 2, it can be seen that for the standard products of chlorpyrifos and acetochlor, the treatment effect of low-temperature plasma activated water is better than that of acidic oxidizing potential water.

[0072] In addition, it should be understood that one or more method steps mentioned in the present invention do not exclude the existence of other method steps before or after the combination step or the insertion of other method steps between these explicitly mentioned steps, unless otherwise specified; and, unless otherwise specified, the numbering of each method step is merely a convenient tool for identifying each method step, and is not intended to limit the order of arrangement of each method step or to define the scope of implementation of the present invention. Changes or adjustments in their relative relationships, without substantially changing the technical content, should also be regarded as the scope of implementation of the present invention.

Claims

1. A low-temperature plasma activated water preparation device, comprising a pulse modulator (1), a voltage regulator and a pulse modulator (2) electrically connected in sequence. (2) and a plasma activated water generating device (3), wherein the plasma activated water generating device (3) comprises a relatively arranged The positive electrode (31) and the negative electrode (32) and the activated water generating container (33) for containing water arranged between the positive electrode (31) and the negative electrode (32) are made of quartz and are characterized in that: A stainless steel gasket (34) for introducing an electric field and shortening a discharge distance is provided in the activated water generating container (33). The stainless steel gasket (34) is immersed in the activated water generating container (33), and its surface is in direct contact with the water body. The thickness of the stainless steel gasket (34) is 2 to 3 mm.

2. A method for removing pesticide residues from Versicolor powder, comprising the following steps: S1. Preparation of low-temperature plasma-activated water: low-temperature plasma-activated water is prepared by the low-temperature plasma-activated water preparation device as claimed in claim 1, with a discharge distance of 8 to 20 mm and a treatment time of 60 to 120 s; S2. Add the crushed and homogenized versicolor powder to the plasma-activated water in step S1, stir, filter, and dry to obtain the versicolor powder with pesticide residue removed. The versicolor powder is soaked in the low-temperature plasma-activated water for at least 30 minutes.

3. The method for removing pesticide residues from Coriolus versicolor powder according to claim 2, characterized in that: In step S1, the voltage of the low-temperature plasma activated water is 90-220V and the frequency is 200-1000Hz.

4. The method for removing pesticide residues from Coriolus versicolor powder according to claim 2, characterized in that: The method further includes S3, detecting the pesticide-residue-removed versicolor powder: extracting and concentrating the pesticide-residue-removed versicolor powder to obtain an extract, and performing gas chromatography-mass spectrometry detection on the extract.

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