Method for removing pesticide residues in silymarin

Abstract

The invention relates to the technical field of plant extracts, in particular to a method for removing pesticide residues in silymarin. According to the method for removing the pesticide residues in the silymarin, the pesticide residues in the silymarin with high pesticide residues can be effectively removed, the removal rate of the pesticide residues is larger than 95%, the total pesticide residues of the silymarin can be effectively reduced, and then a silymarin product with low pesticide residues is prepared; the method has the advantages of simple process, low cost, recoverable solvent and the like, is suitable for industrial production, provides an effective method for industrial production of silymarin with low pesticide residue, and has important significance for improving the safety and application value of silymarin products.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of plant extracts, in particular to a method for removing pesticide residues in silymarin. BACKGROUND

[0002] Silymarin is a flavonoid mixture extracted from the seeds of Silybum marianum, and the main active ingredients are silybin, isosilybin, etc. Silymarin has significant antioxidant, anti-inflammatory and hepatocyte protection effects, and is widely used in drugs (such as liver protectants and detoxification agents), health products and functional food additives. With the increasing incidence of liver disease and the growing demand for natural medicines worldwide, the market size of silymarin has been expanding year by year. However, the raw material Silybum marianum seeds are prone to fungal contamination during cultivation, and farmers generally use fungicides (such as procymidone and carbendazim) to control diseases, resulting in excessive pesticide residues in the raw materials, especially lipid-soluble pesticides that are difficult to remove by conventional purification processes. Therefore, it is necessary to develop a method for efficiently removing pesticide residues in silymarin to improve the safety and quality of silymarin. SUMMARY

[0003] The present application provides a method for removing pesticide residues in silymarin.

[0004] The present application provides a method for removing pesticide residues in silymarin. The existing silymarin purification methods are mostly aimed at removing solvent residues or other impurities in order to improve the overall purity of silymarin, and there is no method for removing pesticide residues in silymarin. During the development of the present application, it was found that the existing silymarin purification methods had poor removal effect on high pesticide residues, and due to the differences in composition and properties of the extracts, the pesticide residue removal methods for other plant extracts often had poor effect when used to remove pesticide residues in silymarin. The present application significantly improves the removal effect of pesticide residues in silymarin by selecting a specific refining solvent and skillfully regulating the polarity gradient and solubility selectivity of the refining solvent, especially when the pesticide residue is high, the removal efficiency is still high.

[0005] Specifically, the present application provides the following technical solutions.

[0006] The present application provides a method for removing pesticide residues in silymarin, which comprises: (1) mixing silymarin with a first refining solvent in a mass ratio of (5-20):1 to obtain a treated product; (2) mixing the treated product with a second refining solvent, then performing solid-liquid separation, and collecting the solid; wherein the first refining solvent is water, and the second refining solvent comprises a mixed solvent of n-hexane and acetone or aqueous acetone.

[0007] In the above method, the high pesticide residue of silymarin is first mixed with water to remove the water-soluble pesticide residue therein. In this step, the water-soluble pesticide residue is dissolved in water, and the silymarin is insoluble in water. It is unexpectedly found that the amount of water added has a greater impact on the removal effect of pesticide residue. It is generally believed that increasing the amount of water added should be better for the dissolution effect of water-soluble pesticide residue, thereby being more conducive to pesticide removal. However, the experimental results show that a higher amount of water usually used is actually not conducive to pesticide removal. Through exploration, it is found that when the mass ratio of silymarin to water is (5-20):1, the pesticide removal efficiency can be significantly improved.

[0008] In the second step of treatment, under the polarity gradient formed by the specific solvent system of n-hexane-acetone, the pesticide residue can be selectively dissolved, while the silymarin remains in the solid phase, and then the fat-soluble pesticide is removed efficiently through solid-liquid separation.

[0009] Preferably, in step (1), the silymarin is mixed with the first refined solvent according to a mass ratio of (5-10):1.

[0010] In the above method, the volume percentage content of acetone in the aqueous acetone solution is not less than 85%; preferably not less than 90%; more preferably not less than 95%.

[0011] By controlling the water content of acetone in the specific solvent system of n-hexane-acetone, the mutual solubility of the solvent can be better prevented, and the loss of silymarin can be avoided.

[0012] In some embodiments of the present application, the second refined solvent comprises a mixed solvent of n-hexane and acetone.

[0013] In some other embodiments of the present application, the second refined solvent comprises a mixed solvent of n-hexane and an aqueous acetone solution, and the volume percentage content of acetone in the aqueous acetone solution is not less than 90%; preferably not less than 95%.

[0014] In the above-mentioned second refined solvent, the volume ratio of n-hexane to acetone or aqueous acetone solution is (60-85):(15-40).

[0015] The specific solvent system of n-hexane-acetone formed according to the above ratio can significantly improve the dissolution efficiency of pesticide residue and reduce the dissolution of silymarin, thereby better balancing the pesticide residue removal efficiency and the yield of silymarin.

[0016] Preferably, in the second refined solvent, the volume ratio of n-hexane to acetone or aqueous acetone solution is (65-80):(20-35).

[0017] The second refining solvent described above does not contain ethyl acetate or alcohol.

[0018] The present application attempts to add commonly used solvents such as ethyl acetate and alcohol to the above-mentioned mixed solvent system of n-hexane and acetone, but it is found that not only can it not further improve the pesticide residue removal effect, but it will significantly reduce the pesticide residue removal efficiency, and the effect of adjusting the volume ratio is still not good. Therefore, the second refining solvent described above preferably does not contain ethyl acetate or alcohol.

[0019] In some embodiments of the present application, the second refining solvent is a mixed solvent of n-hexane and acetone or aqueous acetone.

[0020] In the above method, the ratio of the amount of the second refining solvent to the treated material is 2-6 mL: 1 g.

[0021] In the above method, the mixing of silymarin with the first refining solvent is stirring at 20-40°C.

[0022] Preferably, in step (1), the mixing is stirring at 20-30°C.

[0023] Preferably, in step (1), the stirring time is 5-60 min. More preferably, it is 10-30 min.

[0024] The mixing of silymarin with the first refining solvent can be carried out using a plow or rake type mixing equipment.

[0025] In the above method, the mixing of the treated material with the second refining solvent is stirring at 30-50°C.

[0026] Controlling the treatment temperature of the second refining solvent to be 30-50°C is more conducive to promoting the diffusion and dissolution of pesticide residues, while not damaging the active ingredients of silymarin, significantly improving the safety of the product.

[0027] Preferably, in step (2), the stirring time is 15-60 min. More preferably, it is 20-40 min.

[0028] In order to improve the removal efficiency of pesticide residues, especially in the case of high pesticide residues, step (2) can be repeated multiple times. Preferably, step (2) is repeated 2-10 times. More preferably, step (2) is repeated 3-6 times.

[0029] In the above method, the final collected solid is dried to obtain the silymarin product.

[0030] Preferably, the drying is vacuum drying. The vacuum drying conditions are preferably 70-90°C, vacuum degree -0.08~-0.1 MPa, and drying time 4-8 h.

[0031] In some embodiments of the present application, the method comprises the following steps: (1) mixing the silymarin and the first refining solvent according to a mass ratio of (5-10):1, stirring at 20-30℃ for 10-30min; (2) adding the second refining solvent, the ratio of solid to liquid being 1g:2-6mL, stirring at 30-50℃ for 20-40min, and then separating the solid from the liquid; repeating step (2) for 3-6 times.

[0032] In the present application, the high pesticide residue is preferably not less than 1000ppb; preferably not less than 1500ppb; more preferably not less than 2000ppb.

[0033] In the above method, the total pesticide residue in the silymarin to be treated is not less than 1000ppb; preferably not less than 1500ppb; more preferably not less than 2000ppb.

[0034] In the above method, after drying the solid in step (2), the total pesticide residue is not higher than 100ppb; preferably not higher than 50ppb.

[0035] In the silymarin product prepared by the method for removing pesticide residues of the present application, the total pesticide residue can be not higher than 50ppb.

[0036] In the present application, the pesticide includes fat-soluble pesticides and / or water-soluble pesticides.

[0037] Preferably, the pesticide includes one or more selected from the group consisting of pyrimethanil, procymidone, biphenyl, tebuconazole, chlorpyrifos, diphenylamine, paclobutrazol and carbendazim.

[0038] The method for removing pesticide residues provided by the present application mainly utilizes the solubility characteristics between the refining solvent and the pesticide, and can simultaneously remove water-soluble pesticides and fat-soluble pesticides. The specific types of water-soluble pesticides and fat-soluble pesticides are not particularly limited in principle.

[0039] The beneficial effects of the present application at least include: the method for removing pesticide residues in silymarin provided by the present application can effectively remove the pesticide residues in silymarin with high pesticide residues, achieve efficient removal of water-soluble and fat-soluble pesticides, the pesticide residue removal rate is >95%, and then prepare a low pesticide residue silymarin product, which has the advantages of simple process, low cost and recyclable solvent, and is suitable for industrial production, provides a new method for industrial production of silymarin pesticide residue removal, and has important significance for improving the safety and application value of silymarin products. DETAILED DESCRIPTION

[0040] In order to make the objectives, technical solutions and advantages of the present application clearer, the technical solutions in the present application will be clearly and completely described below. Obviously, the described embodiments are part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative labor fall within the protection scope of the present application.

[0041] In the following examples and comparative examples, the detection method of total pesticide residues refers to GB23200.121-2021 and GB23200.113-2018. The total pesticide residues include fat-soluble pesticides and water-soluble pesticides. The detected fat-soluble pesticides include pyrimethanil, procymidone, diphenylamine, tebuconazole, chlorpyrifos, diphenylamine and paclobutrazol. The detected water-soluble pesticide is mainly carbendazim. Since the water-soluble of silymarin product is poor, the water-soluble pesticide residue is low, and the total pesticide residue is mainly fat-soluble pesticide.

[0042] In the following examples and comparative examples, the detection of silymarin refers to USP 40 Powdered Milk Thistle Extract.

[0043] Example 1 The present embodiment provides a method for removing pesticide residues from silymarin, the steps of which are as follows: (1) 2.5 g of water was added to 25 g of silymarin (total pesticide residues of 2478 ppb, silymarin content of 58.21%), and stirred at 20°C for 10 min; (2) After the stirring in step (1) was completed, 75 mL of a mixed solvent of n-hexane and 95% acetone aqueous solution was added, and the volume ratio of n-hexane to 95% acetone aqueous solution in the mixed solvent was 65:35. 80.2 g of the above mixture was stirred at 48°C for 20 min, and then solid-liquid separation was performed; (3) Step (2) was repeated 3 times; 27 g of the separated lower solid was vacuum dried to obtain 22.93 g of silymarin.

[0044] The total pesticide residues of the silymarin prepared by the above method were 17.4 ppb, the silymarin content was 60.32%, the pesticide residue removal rate was 99.36%, and the extraction yield of silymarin was 95.04%.

[0045] Example 2 The present embodiment provides a method for removing pesticide residues from silymarin, the steps of which are as follows: (1) 5.1 g of water was added to 25.53 g of silymarin (total pesticide residues of 2174 ppb, silymarin content of 59.38%), and stirred at 30°C for 40 min; (2) After the stirring in step (1) is completed, 150 mL of a mixed solvent of n-hexane and acetone is added, the volume ratio of n-hexane to acetone in the mixed solvent being 80:20; 135.63 g of the above mixed solution is stirred at 35°C for 40 min, and then solid-liquid separation is performed; (3) Step (2) is repeated 6 times; 28.42 g of the separated lower layer solid is vacuum dried to obtain 24.25 g of silymarin.

[0046] The total pesticide residue of the silymarin prepared by the above method is 39.1 ppb, the silymarin content is 59.46%, the pesticide residue removal rate is 98.29%, and the silymarin extraction yield is 95.11%.

[0047] Example 3 The present example provides a method for removing pesticide residues from silymarin, the steps of which are as follows: (1) 2.5 g of water is added to 25 g of silymarin (the silymarin used is the same as that in Example 1), and stirring is performed at 20°C for 10 min; (2) After the stirring in step (1) is completed, 75 mL of a mixed solvent of n-hexane and 86% aqueous acetone is added, the volume ratio of n-hexane to 86% aqueous acetone in the mixed solvent being 65:35; 80.2 g of the above mixed solution is stirred at 48°C for 20 min, and then solid-liquid separation is performed; (3) Step (2) is repeated 3 times; 28.3 g of the separated lower layer solid is vacuum dried to obtain 24.38 g of silymarin.

[0048] The total pesticide residue of the silymarin prepared by the above method is 1486 ppb, the silymarin content is 56.01%, the pesticide residue removal rate is 41.52%, and the silymarin extraction yield is 93.83%.

[0049] Comparative Example 1 The present example provides a method for removing pesticide residues from silymarin, the steps of which are as follows: (1) 150 mL of a mixed solvent of n-hexane and acetone is added to 25.53 g of silymarin (the silymarin used is the same as that in Example 2), the volume ratio of n-hexane to acetone in the mixed solvent being 80:20; 130.53 g of the above mixed solution is stirred at 35°C for 40 min, and then solid-liquid separation is performed; (2) The mixed solvent treatment and solid-liquid separation operation in step (1) are repeated 6 times; 29.63 g of the separated lower layer solid is vacuum dried to obtain 18.47 g of silymarin; The total pesticide residue of the prepared silymarin is 2098 ppb, the silymarin content is 60.2%, the pesticide residue removal rate is 30.18%, and the extraction yield of silymarin is 73.34%.

[0050] Comparative Example 2 The present comparative example provides a method for removing pesticide residues in silymarin, and the steps are as follows: (1) 25 g of silymarin (the same silymarin as used in Example 1) is added with 25 g of water, and stirred at 20°C for 10 min; (2) After the stirring in step (1) is completed, 75 mL of a mixed solvent of n-hexane and 95% acetone aqueous solution is added, and the volume ratio of n-hexane and 95% acetone aqueous solution in the mixed solvent is 65:35; 102.5 g of the above mixed solution is stirred at 48°C for 20 min, and then solid-liquid separation is performed; (3) Step (2) is repeated 3 times; 48 g of the separated lower solid is vacuum dried to obtain 23.85 g of silymarin.

[0051] The total pesticide residue of the prepared silymarin is 2059 ppb, the silymarin content is 53.34%, the pesticide residue removal rate is 20.73%, and the extraction yield of silymarin is 87.42%.

[0052] Comparative Example 3 The present comparative example provides a method for removing pesticide residues in silymarin, and the steps are as follows: (1) 25 g of silymarin (the same silymarin as used in Example 1) is added with 2.5 g of water, and stirred at 20°C for 10 min; (2) After the stirring in step (1) is completed, 75 mL of a mixed solvent of n-hexane, ethyl acetate and acetone is added, and the volume ratio of n-hexane, ethyl acetate and acetone in the mixed solvent is 6:4:1; 87.5 g of the above mixed solution is stirred at 48°C for 20 min, and then solid-liquid separation is performed; (3) Step (2) is repeated 3 times; 25.3 g of the separated lower solid is vacuum dried to obtain 21.73 g of silymarin.

[0053] The total pesticide residue of the prepared silymarin is 2143 ppb, the silymarin content is 53.6%, the pesticide residue removal rate is 24.83%, and the extraction yield of silymarin is 80.04%.

[0054] Comparative Example 4 The present comparative example provides a method for removing pesticide residues in silymarin, and the steps are as follows: (1) 2.5 g water was added to 25 g silymarin (the silymarin used is the same as that in Example 1), and stirred at 20°C for 10 min; (2) After the stirring in step (1) was completed, 75 mL of a mixed solvent of n-hexane, ethanol and acetone was added, wherein the volume ratio of n-hexane, ethanol and acetone in the mixed solvent was 6:4:1; 83.75 g of the above mixed solution was stirred at 48°C for 20 min, and then solid-liquid separation was performed; (3) Step (2) was repeated for 3 times; 24.8 g of the separated lower solid was vacuum dried to obtain 21.65 g of silymarin.

[0055] The total pesticide residue of the silymarin prepared by the above method was 2098 ppb, the silymarin content was 46.3%, the pesticide residue removal rate was 26.68%, and the extraction yield of silymarin was 68.88%.

[0056] Finally, it should be noted that: the above examples are only used to illustrate the technical solutions of the present application, but not to limit it; although the present application has been described in detail with reference to the foregoing examples, those skilled in the art should understand that: it can still modify the technical solutions recorded in the foregoing examples, or make equivalent replacement for part of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present application.

Claims

1. A method for removing pesticide residues from silymarin, characterized in that, The method includes: (1) Silymarin and the first refining solvent were mixed at a mass ratio of (5-20):1 to obtain the treated product; (2) The treated material is mixed with a second refining solvent, and then solid-liquid separation is performed to collect the solid. The first refining solvent is water, and the second refining solvent comprises a mixture of hexane and acetone or an aqueous solution of acetone.

2. The method for removing pesticide residues from silymarin according to claim 1, characterized in that, The volume percentage of acetone in the acetone aqueous solution is not less than 85%; preferably not less than 90%; more preferably not less than 95%.

3. The method according to claim 1 or 2, characterized in that, In the second purified solvent, the volume ratio of n-hexane to acetone or aqueous acetone solution is (60-85):(15-40).

4. The method according to any one of claims 1 to 3, characterized in that, The second refining solvent does not contain ethyl acetate or alcohol.

5. The method for removing pesticide residues from silymarin according to any one of claims 1 to 4, characterized in that, The ratio of the amount of the second purified solvent to the treated material is 2-6 mL: 1 g.

6. The method for removing pesticide residues from silymarin according to any one of claims 1 to 5, characterized in that, Silymarin is mixed with the first refined solvent and stirred at 20-40°C; the stirring time is preferably 5-60 min.

7. The method for removing pesticide residues from silymarin according to any one of claims 1 to 6, characterized in that, The treated material is mixed with a second refined solvent and stirred at 30-50°C; the stirring time is preferably 15-60 min.

8. The method for removing pesticide residues from silymarin according to any one of claims 1 to 7, characterized in that, Repeat step (2) 2-10 times.

9. The method for removing pesticide residues from silymarin according to any one of claims 1 to 8, characterized in that, The total pesticide residue in the silymarin is not less than 1000 ppb; preferably not less than 1500 ppb. And / or, after drying the solid in step (2), the total pesticide residue is not higher than 100 ppb; preferably not higher than 50 ppb.

10. The method for removing pesticide residues from silymarin according to any one of claims 1 to 9, characterized in that, The pesticides include fat-soluble pesticides and / or water-soluble pesticides.