Method for removing nitrogen heterocyclic pesticide residues in fruits and vegetables

Abstract

The invention relates to a method for removing nitrogen heterocyclic pesticide residues in fruits and vegetables, and relates to the technical field of pesticide residues. The method comprises the following steps: immersing fruits and vegetables with nitrogen heterocyclic pesticide residues in electrolyzed water, and simultaneously carrying out ultrasonic and ultraviolet radiation treatment to obtain the fruits and vegetables without the nitrogen heterocyclic pesticide residues. According to the method, electrolyzed water is combined with ultrasonic and ultraviolet irradiation technologies, and the method which can be applied to actual production on a large scale and is used for effectively removing nitrogen heterocyclic pesticide residues in fruits and vegetables is provided under the condition that other chemical substances are not additionally added. The method reduces the pesticide residue, can improve the taste and antioxidant activity of fruits and vegetables, is safe and environment-friendly, ensures the quality safety of agricultural products, and has no toxic effect on human bodies. The cleaning machine can be widely used for cleaning fruits and vegetables.

Description

Technical Field

[0001] The invention relates to the technical field of pesticide residues, and in particular to a method for removing nitrogen-containing heterocyclic pesticide residues in fruits and vegetables. Background Art

[0002] Nitrogen-containing heterocyclic fungicides include imidazole fungicides and triazole fungicides. Among them, prochloraz belongs to the imidazole fungicide, which is low in toxicity and a broad-spectrum fungicide. It inhibits the biosynthesis of ergosterol, has a protective and eradication effect, and has a significant preventive effect on various ascomycete and semi-comycete diseases of crops. It has a therapeutic and eradication effect on various diseases on field crops, fruits and vegetables, turf and ornamental plants, and is widely used in the prevention and control of post-harvest diseases of fruits and vegetables. Toxicological studies on prochloraz have found that prochloraz can affect the endocrine system of female mammals to a certain extent, leading to reproductive and developmental malformations. At the same time, its toxicity will increase after degradation in the environment, and it is carcinogenic and teratogenic. Among the different ways in which people are exposed to pesticides, the most likely way of exposure is direct consumption of agricultural products such as fresh fruits and vegetables, and the degradation rate of prochloraz in fruits is very slow. In addition, triazole fungicides represented by difenoconazole have good systemicity and have both protective and therapeutic effects. It has a wide spectrum of fungicides, and foliar or seed treatment can increase crop yield and ensure quality. It has a lasting protective and therapeutic effect on Ascomycetes, Basidiomycetes, and semi-common diseases including Alternaria, Ascochyta, Cercospora, Colletotrichum, Acanthopanax, Phoma, Septoria, Septoria, Venturia, Powdery Fungi, Rustales, and some seed-borne pathogens. It is also very effective against grape anthracnose and white rot. However, its residues on crops and in water bodies pose potential risks to ecosystems, aquatic organisms, and even humans.

[0003] After picking, fruits and vegetables are usually washed with tap water to remove dirt and pesticide residues, but tap water washing has limited effect on removing nitrogen-containing heterocyclic pesticide residues in fruits and vegetables. Therefore, it is necessary to find a method that can effectively remove nitrogen-containing heterocyclic pesticide residues in fruits and vegetables. Summary of the invention

[0004] In order to solve the technical problem of excessive pesticide residues on the surface of fruits and vegetables after the application of nitrogen-containing heterocyclic pesticides, the purpose of the present invention is to provide a method for removing nitrogen-containing heterocyclic pesticide residues in fruits and vegetables. The present invention combines electrolyzed water with ultrasound and ultraviolet irradiation technology, and provides a method for effectively removing nitrogen-containing heterocyclic pesticide residues in fruits and vegetables that can be applied to actual production on a large scale without adding other chemical substances. The method can reduce the amount of pesticide residues, while improving the taste and antioxidant activity of fruits and vegetables, and is safe and environmentally friendly, has no toxic effects on the human body, and ensures the quality and safety of agricultural products. It can be widely used in the cleaning of fruits and vegetables.

[0005] The technical solution of the present invention to solve the above problems is as follows:

[0006] The fruits and vegetables with nitrogen-containing heterocyclic pesticide residues are immersed in electrolyzed water and simultaneously subjected to ultrasound and ultraviolet irradiation treatments to obtain fruits and vegetables with nitrogen-containing heterocyclic pesticide residues removed, while also being able to improve the taste and antioxidant activity of the fruits and vegetables.

[0007] The beneficial effects of the present invention are as follows: the present invention combines electrolyzed water with ultrasound and ultraviolet irradiation technology, and can effectively remove nitrogen-containing heterocyclic pesticide residues in fruits and vegetables without adding other chemicals, while improving the taste and antioxidant activity of fruits and vegetables, being safe and environmentally friendly, and having no toxic effects on the human body. The present invention can be widely used in the cleaning of fruits and vegetables, and is green, efficient, economical and environmentally friendly.

[0008] Based on the above technical solution, the present invention can also be improved as follows.

[0009] Furthermore, the mass ratio of the fruits and vegetables to the electrolyzed water is 2:1-1:5.

[0010] Furthermore, the temperature of the electrolyzed water is 10-70°C.

[0011] Furthermore, the pH of the electrolyzed water is ≥2.

[0012] The beneficial effect of adopting the above further scheme is that electrolyzed water is a general term for acidic ion water or alkaline ion water with special functions produced by changing the pH value, oxidation-reduction potential (ORP) and other indicators of water after water containing electrolytes is continuously passed through a specific electrolytic cell for electrochemical treatment. During the electrolysis process, electrolytic oxidation (EO) water is produced on the anode side of the electrolytic cell, and electrolytic reduction (ER) water is produced on the cathode side. EO water has a strong oxidation potential, an ORP value of more than +1000mV and a pH below 3.0, while ER water has a pH of more than 11.0 and an ORP value of less than -800mV. Compared with ordinary tap water, electrolyzed water can sterilize and disinfect, and has a higher removal rate for pesticides. Different removal effects occur with changes in washing time and temperature and the mass ratio of fruits and vegetables to electrolyzed water.

[0013] Furthermore, the nitrogen-containing heterocyclic pesticide includes at least one of imidazole pesticides and triazole pesticides.

[0014] Furthermore, the ultrasonic treatment power density is 10W / L-40W / L.

[0015] Preferably, the imidazole pesticide is prochloraz, and the triazole pesticide is difenoconazole.

[0016] Furthermore, the frequency of the ultrasonic treatment is 20kHz-60kHz.

[0017] The beneficial effect of adopting the above further scheme is that the present application performs ultrasonic treatment when removing nitrogen-containing heterocyclic pesticide residues, and utilizes the cavitation effect of ultrasound to change or accelerate the change of certain physical, chemical, biological properties or states of the substance, which helps to accelerate the removal of dirt and agricultural chemicals.

[0018] Furthermore, the processing time is 1 min-60 min.

[0019] Furthermore, the wavelength range of the ultraviolet treatment is 200nm-270nm.

[0020] The beneficial effect of adopting the above further scheme is that the ultraviolet irradiation treatment can enhance the oxidative removal effect of nitrogen-containing heterocyclic pesticides by in-situ conversion of low-concentration hydrogen peroxide contained in the solution into ·OH, and the removal effect varies with the treatment time.

[0021] Furthermore, the fruit and vegetable is at least one of kiwi fruit, banana, and cowpea. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 It is a comparative bar graph of the imidazole pesticide residues on the kiwifruit peel in Example 1 and Comparative Examples 1-3 before and after the treatment of the present invention;

[0023] Figure 2 It is a comparative bar graph of the imidazole pesticide residues on the kiwifruit peel in Examples 1-3 and Comparative Examples 1 and 4-5 before and after the treatment of the present invention;

[0024] Figure 3 It is a comparative bar graph of the imidazole pesticide residues on the kiwifruit peel in Example 1, Examples 4-6, Comparative Example 1, and Comparative Examples 6-8 of the present invention;

[0025] Figure 4 It is a comparative bar graph of the imidazole pesticide residues on the kiwifruit peel in Example 1 and Comparative Example 1 and Comparative Examples 9-10 before and after the treatment of the present invention;

[0026] Figure 5 This is a comparative bar graph of the imidazole pesticide residues on kiwifruit peel in Comparative Example 15 and Comparative Examples 11-14 before and after the treatment of the present invention;

[0027] Figure 6 It is a comparative bar graph of the imidazole pesticide residues on the kiwifruit peel in Comparative Examples 15, 17, 19 and Comparative Examples 12, 16, and 18 before and after the treatment of the present invention;

[0028] Figure 7 It is a comparative bar chart of the imidazole pesticide residues on kiwifruit peel in Comparative Examples 12, 15, 20-25 of the present invention;

[0029] Figure 8 It is a bar chart comparing the imidazole pesticide residues on the kiwifruit peel in Example 8 and Comparative Examples 12, 15, and 26 before and after treatment with the present invention. DETAILED DESCRIPTION

[0030] The principles and features of the present invention are described below, and the examples are only used to explain the present invention and are not used to limit the scope of the present invention. If no specific technology or conditions are specified in the embodiments, the technology or conditions described in the literature in this field or the product instructions are used. If the manufacturer of the reagents or instruments used is not specified, they are all conventional products that can be purchased through regular channels.

[0031] Example 1: Removal of nitrogen-containing heterocyclic pesticide residues in fruits and vegetables

[0032] (1) Selecting kiwifruit with good maturity and no obvious surface damage, immersing it in a difenoconazole solution with an active ingredient content of 200 mg / L for 2 minutes, taking it out, and leaving it to stand at room temperature until it is naturally air-dried to obtain the treated kiwifruit;

[0033] (2) immersing the treated kiwifruit in electrolyzed water C at 10°C-70°C and pH greater than 13 at a mass ratio of 1:2; treating the kiwifruit with ultrasound and ultraviolet irradiation for 45 minutes at room temperature, wherein the power density of the ultrasound treatment is 30 W / L, the frequency of the ultrasound treatment is 40 kHz, and the wavelength range of the ultraviolet treatment is 260 nm;

[0034] (3) After the kiwi fruit is treated in step (2), the kiwi fruit is taken out immediately and the moisture on the surface is dried with kitchen paper to obtain the kiwi fruit after the nitrogen-containing heterocyclic pesticide residue is removed.

[0035] Embodiment 2-6:

[0036] The differences between the method for removing pesticide residues in kiwifruit in Example 2-6 and Example 1 are shown in Table 1 below, and the remaining steps are the same as in Example 1:

[0037] Table 1

[0038]

[0039] Example 7: Removal of nitrogen-containing heterocyclic pesticide residues in fruits and vegetables

[0040] (1) Selecting kiwifruit with good maturity and no obvious surface damage, immersing it in a prochloraz solution with an active ingredient content of 200 mg / L for 2 minutes, taking it out, and leaving it to stand at room temperature until it is naturally air-dried to obtain the treated kiwifruit;

[0041] (2) immersing the kiwifruit treated in step 1 in electrolyzed water C at 10° C.-70° C. and pH greater than 13 at a mass ratio of 1:2; combining ultrasonic treatment and ultraviolet irradiation treatment at room temperature for 5 minutes, wherein the power density of the ultrasonic treatment is 30 W / L, the frequency of the ultrasonic treatment is 40 kHz, and the wavelength range of the ultraviolet treatment is 260 nm;

[0042] (3) After the kiwifruit treated in step 3 is processed, the kiwifruit is taken out immediately and the moisture on the surface is absorbed with kitchen paper to obtain the kiwifruit after the prochloraz residue is removed.

[0043] Example 8: Removal of nitrogen-containing heterocyclic pesticide residues in fruits and vegetables

[0044] The method for removing prochloraz pesticide residues in kiwifruit in Example 8 is different from that in Example 7 only in that the ultrasonic treatment and ultraviolet irradiation treatment time are different, and the specific treatment time is 45 minutes. The remaining steps and conditions are the same as those in Example 1.

[0045] Comparative Examples 1-10:

[0046] The differences between the method for removing difenoconazole pesticide residues in kiwifruit in Comparative Example 1-10 and Example 1 are shown in Table 2 below, and the remaining steps are the same as those in Example 1:

[0047] Table 2

[0048]

[0049]

[0050] Comparative Examples 11-26:

[0051] The difference between the method for removing prochloraz pesticide residues in kiwifruit in Comparative Example 11-26 and Example 7 is shown in Table 3, and the remaining steps are the same as those in Example 7:

[0052] Table 3

[0053]

[0054]

[0055] Test Example 1:

[0056] The kiwifruit peels and pulps after the pesticide residues were removed in Examples 1-7 and Comparative Examples 1-26 were separated, the peels were treated with liquid nitrogen and then ground, and the prochloraz residues and difenoconazole residues in the kiwifruit peels were extracted using the QuEChERS method; after extraction, the contents of prochloraz and difenoconazole were determined by high performance liquid chromatography, and the removal rates were calculated. The results are as follows: Figure 1-8 As shown:

[0057] Depend on Figure 1-8 As shown:

[0058] (1) Comparative Example 1, Comparative Example 2, Comparative Example 3, and Example 1 respectively used pure water, electrolyzed water A, electrolyzed water B, and electrolyzed water C to reduce the residual amount of kiwi fruit peel treated with 200 mg / L difenoconazole from 18.55 mg kg -1 Reduced to 11.00 mg kg -1 , 14.73 mg kg -1 , 11.85 mg kg -1 and 9.00 mg kg -1 .Depend on Figure 1 It can be seen that after 45 minutes of treatment with electrolyzed water C combined with ultrasound and ultraviolet irradiation in Example 1, the removal effect of difenoconazole was significantly better than that of other treatments, and the removal rate was relatively the highest, which was 51.48%. This shows that electrolyzed water C has an excellent removal effect on the nitrogen-containing heterocyclic pesticide difenoconazole and can effectively remove triazole pesticides in fruits and vegetables.

[0059] (2) By Figure 2 As shown, after 45 minutes of treatment, the residual amount of difenoconazole in kiwifruit of Examples 1-3, Comparative Example 1, and Comparative Examples 4-5 was reduced to 9.00 mg kg -1 , 8.59 mg kg -1 , 13.05 mg kg -1 , 11.00 mg kg -1 , 13.74 mg kg -1 and 24.10 mg kg -1 .Depend on Figure 2 It can be seen that under the same conditions, the residual amount of fenpropimorph in kiwifruit peel treated with electrolyzed water C was significantly lower than that treated with pure water (P<0.05), and the removal rate of fenpropimorph in kiwifruit peel treated with different concentrations of electrolyzed water C was higher than 51.48%.

[0060] (3) By Figure 3 As shown, after Example 1, Examples 4-6, Comparative Example 1, and Comparative Examples 6-8 were treated with pure water and electrolyzed water C for 5 minutes, 15 minutes, 30 minutes, and 45 minutes, the residual amount of difenoconazole was reduced to 10.30 mg kg -1 -11.98mgkg -1 range and 5.63 mg kg -1 -9.00mg kg -1 range. Figure 3 It can be seen that compared with pure water, within the same treatment time (except for 45 minutes of treatment), electrolyzed water C significantly improved the removal of fenpropimorph residues (P<0.05), and the treatment time had little effect on the removal of fenpropimorph residues in kiwifruit peel.

[0061] (4) By Figure 4 It can be seen that combined with ultraviolet irradiation treatment, there was no significant change in the removal of fenpropimorph residues by pure water (P>0.05), and electrolyzed water C further significantly improved the removal of fenpropimorph residues (P<0.05). Within 5 minutes, the removal rate of fenpropimorph residues by electrolyzed water C combined with ultrasonic treatment and ultraviolet irradiation treatment could reach up to 53.44%.

[0062] (5) By Figure 5 It can be obtained that: Comparative Example 11 uses 2g / L baking soda solution instead of electrolytic water solution to soak kiwi fruit, and the kiwi fruit peel residue is 44.90mg kg -1 Reduced to 25.71 mg kg -1 , which is higher than the 19.01 mg kg residue in the kiwi fruit peel after pure water treatment in Comparative Example 10. -1 Comparative Examples 14, 13 and 15 respectively used electrolyzed water B, electrolyzed water A and electrolyzed water C to reduce the residual amount of kiwi fruit peel treated with 200 mg / L prochloraz from 44.90 mg kg -1 Reduced to 14.88 mg kg -1 , 14.38 mg kg -1 and 10.11 mg kg -1 .Depend on Figure 5 It can be seen that after 45 minutes of solution synergistic ultrasonic treatment, the removal effect of electrolyzed water on prochloraz was significantly better than that of other treatments. It is worth noting that the removal rate of prochloraz in electrolyzed water C treatment was relatively the highest, at 77.49%. This shows that electrolyzed water has an excellent removal effect on nitrogen-containing heterocyclic pesticide prochloraz, and can effectively remove nitrogen-containing heterocyclic pesticides in fruits and vegetables.

[0063] (6) Under the same conditions, only the concentration of the pesticide soaking fruit was different. After the kiwifruit of comparative example 15 was treated with electrolyzed water C for 45 min, the residual amount of prochloraz was reduced to 10.92 mg kg -1 After the kiwifruit of Comparative Example 12 was treated with pure water, the residual amount of prochloraz was reduced to 40.94 mg kg -1 The residual amount of prochloraz in Comparative Example 16 and Comparative Example 17 was reduced to 28.72 mg kg -1 and 17.82 mg kg -1 The residual amount of prochloraz in Comparative Example 18 and Comparative Example 19 was reduced to 80.45 mg kg -1 and 59.05 mg kg -1 .

[0064] Depend on Figure 6It can be seen that the residual amount of prochloraz in kiwifruit peel treated with electrolyzed water C was significantly lower than that treated with pure water (P<0.05), and the removal rate of prochloraz residue in kiwifruit peel treated with 200 mg / L electrolyzed water C was the highest.

[0065] (7) By Figure 7 As shown, after comparative examples 12, 15, and 20-25 were treated with pure water and electrolyzed water C for 5 minutes, 15 minutes, 30 minutes, and 45 minutes, the residual amount of prochloraz was reduced to 39.01 mg kg -1 and 29.65 mg kg -1 ; 31.16mg kg -1 and 23.33 mg kg -1 ; 23.49mg kg -1 and 13.21 mg kg -1 ; 19.01 mg kg -1 and 10.11 mg kg -1 .

[0066] Depend on Figure 7 It can be seen that compared with pure water, electrolyzed water C significantly improved the removal of prochloraz residues within the same treatment time (P<0.05). The removal rate increased with the extension of treatment time.

[0067] (8) By Figure 8 It can be seen that, combined with ultraviolet irradiation treatment, the removal of prochloraz residues in Comparative Example 26 and Example 8 was further significantly improved (P<0.05). Within 5 minutes, the removal rate of prochloraz residues in Example 8 using electrolyzed water C combined with ultrasonic treatment and ultraviolet irradiation treatment was the highest, which was 50.25%.

[0068] Test Example 2:

[0069] The kiwi fruit peel and pulp were separated before and after the treatment in Example 4 and after the pesticide residues were removed in Comparative Example 6, and the sugar-acid ratio, glutathione content, and total phenol content in the pulp of each group were detected. The specific detection method is as follows:

[0070] (1) Determination of sugar-acid ratio: The separated kiwifruit pulp was filtered with gauze and 1 mL of the filtered kiwifruit pulp was taken. The soluble solids and titratable acid of the homogenized mixture of kiwifruit pulp were determined using a portable system (GMK-835F, G-WON, South Korea), and the sugar-acid ratio (the ratio of soluble solids to titratable acid) was calculated.

[0071] (2) Determination of glutathione (GSH) content: 0.1 g of kiwifruit pulp was homogenized with 2 mL of 5% phosphoric acid solution, transferred to a 2 mL centrifuge tube, and centrifuged at 8000 r / min. -1After centrifugation for 10 min, 1 mL of supernatant was taken. 2 mL of phosphate buffered saline (pH = 7) and 0.2 mL of 39.6 g·L -1 The mixture was mixed with 2-nitrobenzoic acid, incubated at room temperature for 5 min, and the absorbance was measured at 412 nm. The GSH content was calculated from a standard curve generated using standard compounds.

[0072] (3) Determination of total phenolic content: The total phenolic content was determined by the Folin-Ciocalteu method: 1.0 g of kiwifruit pulp was homogenized with 5 mL of 60% methanol solution. Ultrasonication was performed for 10 minutes, centrifugation was performed at 8000 rpm and 4°C for 10 minutes, 0.5 mL of the supernatant was mixed with 2.5 mL of Folin-Ciocalteu reagent and incubated at 25°C for 2 minutes to obtain a mixture. Finally, 2 mL of 70 g / L Na2CO3 solution was added to the mixture and incubated at 50°C in the dark for 5 minutes. The absorbance was measured at a wavelength of 760 nm, and the quantitative results were expressed as gallic acid equivalents.

[0073] Table 4 Sugar-acid ratio, glutathione content, and total phenol content test results

[0074]

[0075]

[0076] From Table 4, we can get:

[0077] Compared with the case before treatment in Example 4, the quality indexes such as sugar-acid ratio, glutathione content, and total phenol content in fruits and vegetables were significantly improved after treatment in Example 4 (P<0.05), so that the fruits and vegetables had better taste and higher antioxidant activity. Moreover, compared with Comparative Example 6, the sugar-acid ratio and total phenol content were also significantly improved (P<0.05).

[0078] Although the embodiments of the present invention have been shown and described above, it is to be understood that the above embodiments are exemplary and are not to be construed as limitations of the present invention. A person skilled in the art may change, modify, replace and vary the above embodiments within the scope of the present invention.

Claims

1. A method for removing nitrogen-containing heterocyclic pesticide residues in fruits and vegetables, characterized in that: The method comprises the following steps: immersing fruits and vegetables containing nitrogen-containing heterocyclic pesticide residues in electrolyzed water, and simultaneously subjecting them to ultrasonic and ultraviolet irradiation treatments to obtain fruits and vegetables from which the nitrogen-containing heterocyclic pesticide residues are removed.

2. The method for removing nitrogen-containing heterocyclic pesticide residues in fruits and vegetables according to claim 1, characterized in that: The mass ratio of the fruits and vegetables to the electrolyzed water is 2:1-1:

5.

3. A method for removing nitrogen-containing heterocyclic pesticide residues in fruits and vegetables according to claim 2, characterized in that: The temperature of the electrolyzed water is 10-70°C.

4. A method for removing nitrogen-containing heterocyclic pesticide residues in fruits and vegetables according to claim 3, characterized in that: The pH of the electrolyzed water is ≥2.

5. The method for removing nitrogen-containing heterocyclic pesticide residues in fruits and vegetables according to claim 1, characterized in that: The nitrogen-containing heterocyclic pesticide includes at least one of imidazole pesticides and triazole pesticides.

6. The method for removing nitrogen-containing heterocyclic pesticide residues in fruits and vegetables according to claim 1, characterized in that: The ultrasonic treatment power density is 10W / L-40W / L.

7. A method for removing nitrogen-containing heterocyclic pesticide residues in fruits and vegetables according to claim 6, characterized in that: The frequency of the ultrasonic treatment is 20 kHz-60 kHz.

8. The method for removing nitrogen-containing heterocyclic pesticide residues in fruits and vegetables according to claim 1, characterized in that: The treatment time is 1 min-60 min.

9. The method for removing nitrogen-containing heterocyclic pesticide residues in fruits and vegetables according to claim 1, characterized in that: The ultraviolet treatment wavelength range is 200nm-270nm.

10. The method for removing nitrogen-containing heterocyclic pesticide residues in fruits and vegetables according to claim 1, characterized in that: The fruit and vegetable is at least one of kiwi fruit, banana and cowpea.

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