Method for producing cranberry extract with low pesticide residues

Abstract

The invention relates to the technical field of removal of pesticide residues in plant extracts, and discloses a method for producing a cranberry extract with low pesticide residues, and the method comprises the following steps: S1, pretreatment of cranberries; s2, removing pesticide residues on the surfaces of the cranberries; s3, extracting effective components of the cranberries; the extracting solution is treated through an adsorption device added with composite activated carbon, the flow speed is controlled to be 0.5 L / min to 1 L / min, the adsorption time is 30 min to 90 min, and the composite activated carbon is activated through zinc chloride and potassium permanganate, then modified through APTES and finally combined with sodium alginate; and S5, concentrating and drying the cranberry extract. Pesticide residues in the cranberry extract can be remarkably reduced, meanwhile, rich active ingredients of the cranberry extract are reserved to the maximum extent, and food safety standards and market requirements are met.

Description

Technical Field

[0001] The invention relates to the technical field of removing pesticide residues in plant extracts, and in particular to a method for producing a low-pesticide residue cranberry extract. Background Art

[0002] Cranberry is a fruit rich in natural active substances such as polyphenols, anthocyanins, and vitamin C. Its extracts are widely used in the food, pharmaceutical, and cosmetic industries, especially in anti-oxidation, antibacterial, and anti-aging. However, in the process of cranberry cultivation, the use of pesticides inevitably leads to certain pesticide residues on the surface and inside the fruit, which will have an adverse effect on the quality and safety of the extracts.

[0003] As consumers pay more and more attention to food safety, the production of low pesticide residue (low pesticide residue) cranberry extract has become an important research direction. Some existing cranberry extraction methods mainly focus on the optimization of extraction process and extraction efficiency, but lack a systematic method for effectively reducing pesticide residues in the extract. This results in the extract containing excessive pesticide residues, affecting its market value and safety.

[0004] In the prior art, physical methods such as water washing and heat treatment are usually used to remove some pesticide residues, but these methods often cannot completely solve the problem of pesticide residues. In addition, although chemical methods can remove pesticide residues more thoroughly, there are problems such as solvent residues and reduced extraction efficiency. Summary of the invention

[0005] In view of this, the object of the present invention is to provide a method for producing a low-pesticide residue cranberry extract, which can significantly reduce the pesticide residues in the cranberry extract while retaining its rich active ingredients to the maximum extent to meet food safety standards and market demand.

[0006] The present invention solves the above technical problems by the following technical means:

[0007] A method for producing a low-pesticide residue cranberry extract, the method comprising:

[0008] S1. Pretreatment of cranberries;

[0009] S2. Removal of pesticide residues on the surface of cranberries;

[0010] S3. Extraction of active ingredients from cranberry

[0011] Using 65-85% (v / v) edible ethanol to extract the washed cranberries at 25-40°C for 12-13 hours, and after the extraction, performing solid-liquid separation to obtain an extract and pomace;

[0012] S4. Pesticide residue purification

[0013] The extract is treated by an adsorption device with composite activated carbon, the flow rate is controlled at 0.5-1 L / min, the adsorption time is 30-90 minutes, and the composite activated carbon is first activated by zinc chloride and potassium permanganate, then modified by APTES, and finally combined with sodium alginate;

[0014] S5. Concentration and drying of cranberry extract.

[0015] Ultrasonic cleaning utilizes the cavitation effect produced when sound waves propagate in a liquid medium. When ultrasound passes through a liquid, it generates high-speed tiny bubbles, which release huge local energy when they burst, forming a tiny impact force, effectively removing tiny pesticide particles from the surface and cortex of cranberries. Citric acid solution, as a weak organic acid, has good complexing ability and can effectively decompose and dissolve some pesticide residues. Pesticides are more easily degraded or inactive in an acidic environment, especially some alkaline or weakly acidic pesticides, which are prone to chemical structure changes under the action of citric acid, making pesticide residues easier to remove. In addition, citric acid can further promote the detachment of pesticide residues from the surface of the fruit by reducing surface tension, thereby enhancing the cleaning effect.

[0016] Composite activated carbon is prepared by chemical activation with zinc chloride, forming a large number of micropores and mesoporous structures, significantly increasing the specific surface area of ​​activated carbon and greatly enhancing its adsorption capacity. After adding potassium permanganate, the activated carbon has certain oxygen-containing active functional groups, which is conducive to the adsorption of pesticide residues and can capture and fix pesticide molecules through its porous structure.

[0017] At the same time, 3-aminopropyltriethoxysilane (APTES) is used to modify the activated carbon by amino groups. The amino groups can enhance the selective adsorption of pesticide molecules by activated carbon. The composite of sodium alginate and activated carbon further improves the adsorption performance of the material. Sodium alginate has good adsorption and chelation capabilities and can produce synergistic effects with the surface of activated carbon. Especially for pesticide molecules with strong polarity, sodium alginate can improve the removal efficiency through chelation or electrostatic adsorption. The cross-linked composite activated carbon not only retains the adsorption performance of activated carbon, but also enhances its chemical stability, making it more durable and reusable during the adsorption process.

[0018] Preferably, the cranberry pretreatment in step S1 specifically includes selecting fresh, pest-free, and highly mature cranberry fruits as raw materials, removing damaged and rotten fruits, and then preliminarily washing the cranberries.

[0019] Preferably, the removal of pesticide residues on the surface of cranberries in step S2 is specifically performed by ultrasonically cleaning the pretreated cranberry fruits for 20-30 minutes, with the ultrasonic frequency set to 30-40 kHz, and then immersing the cranberry fruits in a 0.5%-1.0% citric acid solution for 10-15 minutes.

[0020] Preferably, the composite activated carbon preparation step of step S4 comprises:

[0021] A1. Wash and dry the agricultural and forestry waste, crush it, soak the agricultural and forestry waste powder in a 4-6% ZnCl2 solution for 10-14 hours, filter it under reduced pressure, dry the filter cake, calcine it at 250-350℃ for 1-2 hours, then heat it to 400-500℃ and continue calcining for 1.5-2.5 hours, grind the calcined product, add 2-4 mol / L potassium permanganate solution, soak it and stir it for 2-3 hours, filter it, wash it, and vacuum dry it for 23-25 ​​hours to obtain activated carbon powder;

[0022] A2. The activated carbon powder was dispersed in ethanol, ultrasonically treated for 25-35 minutes, APTES was slowly added, and the reaction was stirred at 55-65°C for 3.5-4.5 hours. The activated carbon was filtered and repeatedly washed with distilled water and ethanol until the pH of the washing solution was close to neutral, and dried to obtain amino-modified activated carbon;

[0023] A3. Sodium alginate and 4-6% acetic acid aqueous solution are mixed and stirred evenly, and then activated carbon powder is added. After stirring and dispersing evenly, a cross-linking agent is added, and the mixture is stirred at 60-80°C for 1.5-2.5 h for cross-linking and compounding. The mixture is then washed with 0.1 mol / L NaOH solution, distilled water and ethanol respectively, and freeze-dried to obtain composite activated carbon.

[0024] Using sugarcane bagasse, rice straw, corn cob, wheat straw and other agricultural and forestry waste as raw materials to prepare activated carbon can effectively utilize agricultural waste, fill the shortage of activated carbon raw materials, and reduce the production cost of activated carbon. 2+ It will react with organic matter in agricultural and forestry waste to a certain extent and play a pre-activation role. This step provides a better structural basis for subsequent activation by increasing the specific surface area and generating preliminary pores. Next, the agricultural and forestry waste is calcined at high temperature to decompose organic matter, release volatile substances, and form a porous structure. After adding potassium permanganate, the activated carbon has certain oxygen-containing active functional groups, which is conducive to the adsorption of agricultural residues and organic matter, and can capture and fix pesticide molecules through its porous structure.

[0025] Activated carbon is modified by amino modification using 3-aminopropyltriethoxysilane (APTES). The amino functional groups in APTES can react with the carboxyl and hydroxyl groups on the surface of activated carbon to form an amino-modified surface structure. The amino groups can enhance the selective adsorption of pesticide molecules by activated carbon, especially through hydrogen bonding or electrostatic adsorption, which can significantly improve the adsorption capacity of charged or polar pollutants.

[0026] The prepared activated carbon powder is added to the sodium alginate solution, stirred to make it uniformly dispersed, and then a cross-linking agent is added to carry out a cross-linking reaction. Due to the high hydrophilicity and polarity of sodium alginate, it can effectively undergo electrostatic adsorption and hydrogen bonding with polar pollutants in water, thereby improving the removal efficiency of these pollutants. The cross-linking process allows the molecular chain of sodium alginate to form a stable composite structure with the activated carbon powder, increasing the mechanical strength and chemical stability of the activated carbon. At the same time, the porous structure of sodium alginate helps to enhance the adsorption capacity of pesticide residues in cranberry extract.

[0027] Preferably, the agricultural and forestry waste in step A1 is a mixture of one or more of bagasse, rice straw, corn cobs and wheat straw.

[0028] Further preferably, the agricultural and forestry waste in step A1 is bagasse.

[0029] Preferably, the ratio of agricultural and forestry waste to ZnCl2 solution in step A1 is 1:2.

[0030] Preferably, the mixing ratio of sodium alginate and activated carbon powder in step A2 is 1:3.

[0031] Preferably, the cross-linking agent in step A2 is one of glutaraldehyde solution and CaCl2 solution.

[0032] Further preferably, the cross-linking agent in step A2 is glutaraldehyde solution.

[0033] Preferably, the step S5 specifically comprises filtering and concentrating the extract obtained in step S4 in sequence to obtain a cranberry extract with low pesticide residues.

[0034] Preferably, the filtration in step S5 is performed by using an ultrafiltration membrane with a pore size of 0.1-0.5 μm, and the concentration is performed by performing reduced pressure concentration at 40-50° C.

[0035] Beneficial effects of the present invention:

[0036] (1) The activated carbon prepared by zinc chloride chemical activation method has a high specific surface area and rich microporous structure, which can significantly improve the adsorption capacity of pesticide residues. Potassium permanganate makes the activated carbon have certain oxygen-containing active functional groups, which is conducive to the adsorption of pesticide residues; 3-aminopropyltriethoxysilane (APTES) is used to modify the activated carbon by amino groups, and the amino groups can enhance the selective adsorption of pesticide molecules by activated carbon; the composite cross-linking of sodium alginate and activated carbon further increases the stability and mechanical strength of the adsorption material, ensuring long-term effectiveness during the extraction process. The composite activated carbon not only has the physical adsorption characteristics of traditional activated carbon, but also enhances the adsorption effect of polar substances in cranberry extract due to the presence of sodium alginate. This makes the composite activated carbon show higher adsorption efficiency when removing pesticide residues from cranberry extract.

[0037] (2) The combined use of ultrasonic cleaning, citric acid soaking and composite activated carbon adsorption can effectively remove pesticide residues from the surface of cranberry fruit and in the extract. Each step plays a corresponding role in different pesticide removal mechanisms, and ultimately the pesticide residue content meets strict food safety standards. Compared with a single purification step, the combined technology greatly improves the removal efficiency, significantly reducing the level of pesticide residues in the treated cranberry extract.

[0038] (3) The processing conditions of the method for producing low-pesticide residue cranberry extract of the present invention are mild, especially in the extraction process and purification process, the temperature and chemical environment are moderately controlled, and the key active ingredients in cranberry will not be damaged. This makes the final extract not only low in pesticide residues, but also retains the biological activity of cranberry, ensuring the functionality and nutritional value of the product. DETAILED DESCRIPTION

[0039] The following will be combined with the specific embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention:

[0040] Example 1

[0041] This example is a preparation method of composite activated carbon.

[0042] The preparation steps of composite activated carbon are as follows:

[0043] A1. Wash and dry 1kg of bagasse, crush it, soak the bagasse powder in 2L of 4% ZnCl2 solution for 10h, filter it under reduced pressure, dry the filter cake, calcine it at 250℃ for 2h, then heat it to 400℃ and continue calcining for 2.5h, grind the calcined product, soak it in 2mol / L potassium permanganate solution and stir it for 3h, filter it, wash it, and vacuum dry it for 23h to obtain 540g of activated carbon powder;

[0044] A2. 540 g of activated carbon powder was dispersed in ethanol, ultrasonically treated for 25 minutes, 54 g of APTES was slowly added, stirred at 55 ° C for 4.5 h, filtered and repeatedly washed with distilled water and ethanol until the pH of the washing solution was close to neutral, and dried to obtain amino-modified activated carbon;

[0045] A3.180g sodium alginate was mixed with 540mL 4% acetic acid aqueous solution and stirred evenly, then 540g activated carbon powder was added, and after being dispersed evenly, 5mL glutaraldehyde was added and stirred at 60℃ for 1.5h for cross-linking and compounding. Then, the mixture was washed with 0.1 mol / L NaOH solution, distilled water and ethanol respectively, and freeze-dried to obtain composite activated carbon.

[0046] Example 2

[0047] This example is a preparation method of composite activated carbon.

[0048] The preparation steps of composite activated carbon are as follows:

[0049] A1. Wash and dry 1kg of bagasse, crush it, soak the bagasse powder in 2L of 5% ZnCl2 solution for 12h, filter it under reduced pressure, dry the filter cake, calcine it at 300℃ for 1.5h, then heat it up to 450℃ and continue calcining for 2h. Grind the calcined product, soak it in 3 mol / L potassium permanganate solution and stir it for 2.5h, filter it, wash it, and vacuum dry it for 24h to obtain 540g of activated carbon powder.

[0050] A2. 540 g of activated carbon powder was dispersed in ethanol, ultrasonically treated for 30 minutes, 54 g of APTES was slowly added, stirred and reacted at 60 ° C for 4 hours, filtered and the activated carbon was repeatedly washed with distilled water and ethanol until the pH of the washing solution was close to neutral, and dried to obtain amino-modified activated carbon;

[0051] A3.180g sodium alginate and 540mL 5% acetic acid aqueous solution were mixed and stirred evenly, and then 540g activated carbon powder was added. After stirring and dispersing evenly, 5mL glutaraldehyde was added and stirred at 70℃ for 2h for cross-linking and compounding. Then, the mixture was washed with 0.1mol / L NaOH solution, distilled water and ethanol respectively, and freeze-dried to obtain composite activated carbon.

[0052] Example 3

[0053] This example is a preparation method of composite activated carbon.

[0054] A1. Wash and dry 1 kg of bagasse, crush it, soak the bagasse powder in 2 L of 6% ZnCl2 solution for 10 h, filter under reduced pressure, dry the filter cake, calcine at 350 °C for 1 h, then heat to 500 °C and continue calcining for 1.5 h. Grind the calcined product, soak it in 4 mol / L potassium permanganate solution and stir it for 2 h, filter it, wash it, and vacuum dry it for 25 h to obtain 540 g of activated carbon powder.

[0055] A2. 540 g of activated carbon powder was dispersed in ethanol, ultrasonically treated for 35 minutes, 54 g of APTES was slowly added, stirred and reacted at 65 ° C for 3.5 hours, filtered and the activated carbon was repeatedly washed with distilled water and ethanol until the pH of the washing solution was close to neutral, and dried to obtain amino-modified activated carbon;

[0056] A3.180g sodium alginate was mixed with 540mL 6% acetic acid aqueous solution and stirred evenly, then 540g activated carbon powder was added, and after being dispersed evenly, 5mL glutaraldehyde was added and stirred at 80℃ for 2.5h for cross-linking and compounding. Then, the mixture was washed with 0.1 mol / L NaOH solution, distilled water and ethanol respectively, and freeze-dried to obtain composite activated carbon.

[0057] Example 4

[0058] This embodiment is a method for producing a low pesticide residue cranberry extract.

[0059] S1. Pretreatment of cranberries

[0060] Select 2kg of fresh, pest-free and mature cranberry fruits as raw materials, remove damaged and rotten fruits, and then perform preliminary cleaning on the cranberries;

[0061] S2. Removal of pesticide residues on cranberry surface

[0062] 1.8 kg of pretreated cranberry fruits were ultrasonically cleaned for 20 minutes, and then immersed in 5.4 L of 0.5% citric acid solution for 15 minutes;

[0063] S3. Extraction of active ingredients from cranberry

[0064] 1.8 kg of washed cranberries were extracted with 3.4 L of 65% (v / v) edible ethanol at 25°C for 12 hours, and 2.8 L of extract and pomace were obtained by centrifugation after the extraction.

[0065] S4. Pesticide residue purification

[0066] 2.8 L of the extract was treated by an adsorption device containing 300 g of the composite activated carbon of Example 1, with the flow rate controlled at 0.5 L / min and the adsorption time being 90 minutes;

[0067] S5. Cranberry extract concentration and drying

[0068] The extract obtained in step S4 is filtered and concentrated in sequence to obtain a cranberry extract with low pesticide residues. The filtration is performed using an ultrafiltration membrane with a pore size of 0.1 μm, and the concentration is performed under reduced pressure at 40°C.

[0069] Example 5

[0070] This embodiment is a method for producing a low pesticide residue cranberry extract.

[0071] S1. Pretreatment of cranberries

[0072] Select 2kg of fresh, pest-free and mature cranberry fruits as raw materials, remove damaged and rotten fruits, and then perform preliminary cleaning on the cranberries;

[0073] S2. Removal of pesticide residues on cranberry surface

[0074] 1.8 kg of pretreated cranberry fruits were ultrasonically cleaned for 25 minutes, and then immersed in 5.4 L of 0.75% citric acid solution for 12.5 minutes;

[0075] S3. Extraction of active ingredients from cranberry

[0076] 1.8 kg of washed cranberries were extracted with 3.4 L of 75% (v / v) edible ethanol at 32.5°C for 12.5 hours, and 2.8 L of extract and pomace were obtained by centrifugation after the extraction.

[0077] S4. Pesticide residue purification

[0078] 2.8 L of the extract was treated by an adsorption device containing 300 g of the composite activated carbon of Example 2, with the flow rate controlled at 0.75 L / min and the adsorption time being 60 minutes;

[0079] S5. Cranberry extract concentration and drying

[0080] The extract obtained in step S4 is filtered and concentrated in sequence to obtain a cranberry extract with low pesticide residues. The filtration is performed using an ultrafiltration membrane with a pore size of 0.3 μm, and the concentration is performed under reduced pressure at 45°C.

[0081] Example 6

[0082] This embodiment is a method for producing a low pesticide residue cranberry extract.

[0083] S1. Pretreatment of cranberries

[0084] Select 2kg of fresh, pest-free and mature cranberry fruits as raw materials, remove damaged and rotten fruits, and then perform preliminary cleaning on the cranberries;

[0085] S2. Removal of pesticide residues on cranberry surface

[0086] 1.8 kg of the pretreated cranberry fruits were ultrasonically cleaned for 30 minutes, and then immersed in 5.4 L of 1.0% citric acid solution for 10 minutes;

[0087] S3. Extraction of active ingredients from cranberry

[0088] 1.8 kg of washed cranberries were extracted with 3.4 L of 85% (v / v) edible ethanol at 40°C for 13 hours, and 2.8 L of extract and pomace were obtained by centrifugation after the extraction.

[0089] S4. Pesticide residue purification

[0090] 2.8 L of the extract was treated by an adsorption device containing 300 g of the composite activated carbon of Example 3, with the flow rate controlled at 1 L / min and the adsorption time being 30 minutes;

[0091] S5. Cranberry extract concentration and drying

[0092] The extract obtained in step S4 is filtered and concentrated in sequence to obtain a cranberry extract with low pesticide residues. The filtration is performed using an ultrafiltration membrane with a pore size of 0.5 μm, and the concentration is performed under reduced pressure at 50°C.

[0093] Comparative Example 1

[0094] The difference between this embodiment and embodiment 5 is that the composite activated carbon is replaced with ordinary activated carbon.

[0095] Comparative Example 2

[0096] The difference between this embodiment and embodiment 5 is that the composite activated carbon is replaced with ordinary sodium alginate.

[0097] The embodiment of the present invention adopts liquid chromatography-gas chromatography-mass spectrometry (GC-MS) to detect pesticide residues.

[0098] Table 1 shows the removal rates of pesticide residues in different embodiments.

[0099]

[0100] The composite activated carbon showed a very high effect in removing pesticide residues such as niclosamide, permethrin, thiophanate-methyl and acetamiprid. Compared with Comparative Examples 1 and 2, the composite activated carbon can significantly improve the removal rate of pesticide residues, especially for common pesticides, showing strong adsorption and purification capabilities.

[0101] The above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit the present invention. Although the present invention is described in detail with reference to the preferred embodiments, it should be understood by those skilled in the art that the technical solutions of the present invention may be modified or replaced by equivalents without departing from the purpose and scope of the technical solutions of the present invention, which should be included in the scope of the claims of the present invention. The techniques, shapes, and structural parts not described in detail in the present invention are all known technologies.

Claims

1. A method for producing a low pesticide residue cranberry extract, characterized in that: The method comprises, S1. Pretreatment of cranberries; S2. Removal of pesticide residues on the surface of cranberries; S3. Extraction of active ingredients from cranberry Using 65-85% (v / v) edible ethanol to extract the washed cranberries at 25-40°C for 12-13 hours, and after the extraction, performing solid-liquid separation to obtain an extract and pomace; S4. Pesticide residue purification The extract is processed through an adsorption device with composite activated carbon, with the flow rate controlled at 0.5-1 L / min and the adsorption time at 30-90 minutes; S5. Concentration and drying of cranberry extract.

2. The method according to claim 1, characterized in that: The cranberry pretreatment in step S1 specifically includes selecting fresh, pest-free, and highly mature cranberry fruits as raw materials, removing damaged and rotten fruits, and then preliminarily washing the cranberries.

3. The method according to claim 1, characterized in that: The step S2 of removing pesticide residues on the surface of cranberries specifically comprises: subjecting the pretreated cranberry fruits to ultrasonic cleaning for 20-30 minutes, with the ultrasonic frequency set to 30-40 kHz, and then immersing the cranberry fruits in a 0.5%-1.0% citric acid solution for 10-15 minutes.

4. The method according to claim 1, characterized in that: The composite activated carbon preparation step of step S4 comprises: A1. Wash and dry the agricultural and forestry waste, crush it, soak the agricultural and forestry waste powder in a 4-6% ZnCl2 solution for 10-14 hours, filter it under reduced pressure, dry the filter cake, calcine it at 250-350℃ for 1-2 hours, then heat it to 400-500℃ and continue calcining for 1.5-2.5 hours, grind the calcined product, add 2-4 mol / L potassium permanganate solution, soak it and stir it for 2-3 hours, filter it, wash it, and vacuum dry it for 23-25 ​​hours to obtain activated carbon powder; A2. The activated carbon powder was dispersed in ethanol, ultrasonically treated for 25-35 minutes, APTES was slowly added, and the reaction was stirred at 55-65°C for 3.5-4.5 hours. The activated carbon was filtered and repeatedly washed with distilled water and ethanol until the pH of the washing solution was close to neutral, and dried to obtain amino-modified activated carbon; A3. Sodium alginate and 4-6% acetic acid aqueous solution are mixed and stirred evenly, and then amino-modified activated carbon is added. After stirring and dispersing evenly, a cross-linking agent is added, and the mixture is stirred at 60-80°C for 1.5-2.5 h for cross-linking and compounding. The mixture is then washed with 0.1 mol / L NaOH solution, distilled water and ethanol respectively, and freeze-dried to obtain composite activated carbon.

5. The method according to claim 4, characterized in that: The agricultural and forestry waste in step A1 is a mixture of one or more of bagasse, rice straw, corn cobs and wheat straw.

6. The method according to claim 4, characterized in that: The ratio of the agricultural and forestry waste to the ZnCl2 solution in step A1 is 1:

2.

7. The method according to claim 4, characterized in that: The mixing ratio of sodium alginate and activated carbon powder in step A2 is 1:

3.

8. The method according to claim 4, characterized in that: The cross-linking agent in step A2 is one of glutaraldehyde solution and CaCl2 solution.

9. The method according to claim 1, characterized in that: The step S5 specifically comprises filtering and concentrating the extract obtained in step S4 in sequence to obtain a cranberry extract with low pesticide residues.

10. The method according to claim 9, characterized in that: The filtration in step S5 is performed by using an ultrafiltration membrane with a pore size of 0.1-0.5 μm, and the concentration is performed by reducing pressure at 40-50° C.

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