Step-by-step extraction method of organic selenium in natural selenium-rich agricultural products

Abstract

The invention relates to the technical field of nutrient element extraction, and discloses a step-by-step extraction method of organic selenium in natural selenium-rich agricultural products, which comprises the following steps: cleaning, drying and crushing the natural selenium-rich agricultural products into fine powder; then sequentially using an aqueous solution containing a buffer agent, low-concentration ethanol and a high-concentration organic solvent for ultrasonic-assisted extraction to respectively obtain water-soluble, hydrophilic, hydrophobic and fat-soluble organic selenium compounds; and finally, combining the extracting solutions in the steps, and carrying out rotary evaporation concentration and purification treatment to obtain the high-purity organic selenium compound. Through a step-by-step extraction method, different types of organic selenium compounds in natural selenium-rich agricultural products are efficiently extracted by using the aqueous solution, the low-concentration ethanol and the high-concentration organic solvent respectively under low-temperature and mild conditions, so that high purity and biological activity are kept, meanwhile, the process flow is simplified, and the production cost is reduced. The energy consumption and the use of organic solvents are reduced, the environmental pollution is reduced, and the method is suitable for large-scale industrial production.

Description

Technical Field

[0001] The present invention relates to the technical field of nutrient element extraction, and particularly to a step-by-step extraction method for organic selenium in natural selenium-rich agricultural products. Background Art

[0002] Selenium (Se), as a trace element crucial for human health, has multiple biological functions such as antioxidation, enhancing immunity, promoting cell repair, and preventing various diseases. In recent years, with the increasing emphasis on health and the growing demand for functional foods by people, the development and utilization of natural selenium-rich agricultural products have received extensive attention. However, traditional organic selenium extraction methods have many deficiencies, restricting their potential in industrial production and wide application. Currently, commonly used extraction methods mainly include acid-base treatment, enzymatic hydrolysis, and organic solvent extraction. Although these methods can extract organic selenium to a certain extent, they generally suffer from problems such as low efficiency, high cost, complex operation, and environmental unfriendliness. For example, acid-base treatment may cause degradation or denaturation of organic selenium compounds, affecting their biological activities; while organic solvent extraction may introduce harmful residues, and the large-scale use of organic solvents not only increases production costs but also poses a risk of environmental pollution. In addition, traditional methods often cannot comprehensively extract different types of organic selenium compounds, resulting in limitations in the purity and application scope of the extracts. Therefore, developing an extraction method that is efficient, mild, environmentally friendly, and can maintain the biological activity of organic selenium is of great practical significance and broad application prospects for enhancing the added value of natural selenium-rich agricultural products and meeting the market demand for high-purity organic selenium products. Therefore, we have proposed a step-by-step extraction method for organic selenium in natural selenium-rich agricultural products. Summary of the Invention

[0003] The main purpose of the present invention is to provide a step-by-step extraction method for organic selenium in natural selenium-rich agricultural products, which can effectively solve the problems in the background art.

[0004] To achieve the above purpose, the technical solution adopted by the present invention is as follows:

[0005] A step-by-step extraction method for organic selenium in natural selenium-rich agricultural products, comprising the following steps:

[0006] S1: Clean the natural selenium-rich agricultural products, remove impurities and then dry them. Crush and sieve the dried natural selenium-rich agricultural products to obtain fine powder;

[0007] S2: Add the crushed raw materials to an aqueous solution containing a buffer at a ratio of 1:10 w / v, adjust the pH value to 6.5 - 7.0, perform ultrasonic treatment to obtain a mixed system A, and then transfer it to a refrigerated centrifuge for centrifugation. After centrifugation, separate the precipitate to obtain an extract a containing water-soluble organic selenium in the aqueous phase and a precipitate a;

[0008] S3: Ultrasonically treat precipitate a with low-concentration ethanol to obtain a mixed system B. After centrifugation, separate the precipitate to obtain an extract b containing hydrophilic and hydrophobic organic selenium and a precipitate b.

[0009] S4: Ultrasonically treat precipitate b with a high-concentration organic solvent in the same manner as the above steps to obtain a mixed system C. After centrifugation, separate the precipitate to obtain an extract c containing fat-soluble organic selenium and a precipitate c.

[0010] S5: Combine the above-obtained leaching solution a for extracting water-soluble organic selenium from the aqueous phase, extract b containing hydrophilic and hydrophobic organic selenium, and extract c containing fat-soluble organic selenium to obtain a mixed solution containing different types of organic selenium compounds. Rotate and evaporate and concentrate it under low-temperature conditions of 35 - 40 °C, and purify the concentrated extract to obtain organic selenium compounds.

[0011] Preferably, in S1, the drying temperature is 35 - 40 °C, and the pulverized natural selenium-rich agricultural products are sieved through a 120-mesh sieve.

[0012] Preferably, in S2, the buffer is selected from any one of phosphate buffer solution and Tris-HCl buffer solution.

[0013] Preferably, in S2, ultrasonically treat under low-temperature conditions of 10 - 15 °C for a treatment duration of 15 - 30 min, with an ultrasonic frequency of 20 - 40 kHz and an ultrasonic power of 50 - 150 W.

[0014] Preferably, in S2, the centrifugation speed is 4000 - 5000 rpm, and the centrifugation duration is 10 - 15 min.

[0015] Preferably, in S3, the specific steps are as follows:

[0016] S301: Add precipitate a to low-concentration ethanol at a ratio of 1:10 w / v, gently stir evenly, place the mixture in an ultrasonic cleaner, and ultrasonically treat it under low-temperature conditions of 10 - 15 °C for 15 - 30 min to obtain a mixed system B.

[0017] S302: Transfer the mixed system B to a refrigerated centrifuge, centrifuge at a speed of 4000 - 5000 rpm for 8 - 12 min, and after centrifugation, separate the precipitate to obtain an extract b containing hydrophilic and hydrophobic organic selenium and a precipitate b.

[0018] Preferably, in S301, the ultrasonic frequency and ultrasonic power of the ultrasonic treatment are the same as those of the ultrasonic treatment in S2.

[0019] Preferably, in the step S301, the low-concentration ethanol is an ethanol solution with a concentration of 20-35%.

[0020] Preferably, in the step S4, the high-concentration organic solvent is any one selected from acetone with a concentration of 80-100% and methanol with a concentration of 80-100%.

[0021] Preferably, in the step S5, before concentrating the mixed solution, it further includes: preliminarily filtering the combined mixed solution using a microporous filter membrane.

[0022] Compared with the prior art, the present invention has the following beneficial effects:

[0023] 1. Through the step-by-step extraction method, the present invention separately uses an aqueous solution, low-concentration ethanol, and high-concentration organic solvent to perform step-by-step extraction on the organic selenium in natural selenium-rich agricultural products, ensuring the efficient extraction of different types of organic selenium compounds. From water-soluble organic selenium to hydrophilic and hydrophobic organic selenium, and then to lipid-soluble organic selenium, each step is optimized for a specific type of organic selenium, not only improving the total extraction rate but also significantly enhancing the purity of the final product, ensuring the comprehensiveness and efficiency of the extraction.

[0024] 2. Throughout the extraction process of the present invention, key parameters such as temperature, pH value, and ultrasonic power are strictly controlled to ensure operation under low temperature (10-15°C) and mild conditions, avoiding the destruction of organic selenium by high temperature, strong acids or bases, or violent mechanical action. By using a buffer solution to adjust the pH value to 6.5-7.0 and adopting a moderate ultrasonic power (50-150W), the structural integrity and biological activity of organic selenium are effectively protected, making the final product have higher application value, especially in the fields of functional foods, health products, and pharmaceutical raw materials.

[0025] 3. The present invention adopts a variety of environmentally friendly and energy-saving technical means, which conforms to the principles of green chemistry. Water and low-concentration ethanol are preferentially used as extraction solvents, reducing the usage amount of organic solvents and the discharge of waste; through rotary evaporation concentration and freeze-drying technology, most of the solvents can be effectively removed, facilitating subsequent solvent recovery and reuse, and saving resources. In addition, low-temperature treatment and moderate ultrasonic power further reduce energy consumption, reducing energy consumption and achieving a double improvement in environmental protection and economic benefits.

[0026] 4. The step-by-step extraction method of the present invention simplifies the production process and improves production efficiency. Through preliminary filtration and centrifugal separation, the generation of solid residues is reduced, and the difficulty of subsequent purification is lowered. After the combined mixed solution is concentrated by rotary evaporation, it can be directly purified, shortening the entire extraction cycle, ensuring the simplicity and repeatability of the operation, being applicable to large-scale industrial production, and bringing significant economic benefits to enterprises. Description of the Drawings

[0027] Figure 1 This is a flow chart of the step-by-step extraction method of organic selenium in a natural selenium-rich agricultural product of the present invention. Detailed implementation manners

[0028] To make the technical means, creative features, achieved purposes and functions of the present invention easy to understand, the present invention will be further described below in conjunction with specific implementation manners.

[0029] As Figure 1 shown, a step-by-step extraction method of organic selenium in a natural selenium-rich agricultural product includes the following steps:

[0030] S1: Clean the natural selenium-rich agricultural product, remove impurities and then dry it. Crush and sieve the dried natural selenium-rich agricultural product to obtain fine powder;

[0031] Among them, the drying temperature is 35 - 40 °C, and the crushed natural selenium-rich agricultural product is sieved through a 120-mesh sieve.

[0032] S2: Add the crushed raw material to an aqueous solution containing a buffer in a ratio of 1:10 w / v, adjust the pH value to 6.5 - 7.0, perform ultrasonic treatment to obtain a mixed system A, and then transfer it to a refrigerated centrifuge for centrifugation. After centrifugation, separate the precipitate to obtain an extract a containing water-soluble organic selenium in the aqueous phase and a precipitate a;

[0033] Among them, the buffer is selected from any one of phosphate buffer solution and Tris-HCl buffer solution.

[0034] Among them, ultrasonic treatment is carried out under low-temperature conditions of 10 - 15 °C, the treatment duration is 15 - 30 min, the ultrasonic frequency is 20 - 40 kHz, and the ultrasonic power is 50 - 150 W.

[0035] Among them, the centrifugation speed is 4000 - 5000 rpm, and the centrifugation duration is 10 - 15 min.

[0036] S3: Perform ultrasonic treatment on the precipitate a with low-concentration ethanol to obtain a mixed system B. After centrifugation, separate the precipitate to obtain an extract b containing hydrophilic and hydrophobic organic selenium and a precipitate b;

[0037] Among them, the specific steps are:

[0038] S301: Add the precipitate a to low-concentration ethanol in a ratio of 1:10 w / v, gently stir evenly, place the mixture in an ultrasonic cleaner, and perform ultrasonic treatment for 15 - 30 min under low-temperature conditions of 10 - 15 °C to obtain a mixed system B;

[0039] Furthermore, the ultrasonic frequency and ultrasonic power of the ultrasonic treatment are the same as those of the ultrasonic treatment in S2.

[0040] Furthermore, the low-concentration ethanol is an ethanol solution with a concentration of 20-35%.

[0041] S302: Transfer the mixed system B to a refrigerated centrifuge and centrifuge at a speed of 4000-5000 rpm for 8-12 min. After centrifugation, separate the precipitate to obtain an extract b containing hydrophilic and hydrophobic organic selenium and a precipitate b.

[0042] S4: Ultrasonically treat the precipitate b with a high-concentration organic solvent in the same manner as the above steps to obtain a mixed system C. After centrifugation, separate the precipitate to obtain an extract c containing lipophilic organic selenium and a precipitate c;

[0043] Among them, the high-concentration organic solvent is selected from any one of acetone with a concentration of 80-100% and methanol with a concentration of 80-100%.

[0044] S5: Combine the above-obtained leaching solution a for extracting water-soluble organic selenium in the aqueous phase, extract b containing hydrophilic and hydrophobic organic selenium, and extract c containing lipophilic organic selenium to obtain a mixed solution containing different types of organic selenium compounds. Rotate and evaporate and concentrate the mixed solution under low-temperature conditions of 35-40 °C, and purify the concentrated extract to obtain organic selenium compounds.

[0045] Among them, before concentrating the mixed solution, it also includes: preliminarily filtering the combined mixed solution using a microporous filter membrane.

[0046] The present invention uses a step-by-step extraction method to separately extract organic selenium in natural selenium-rich agricultural products using aqueous solution, low-concentration ethanol, and high-concentration organic solvents in steps, ensuring the efficient extraction of different types of organic selenium compounds. From water-soluble organic selenium to hydrophilic and hydrophobic organic selenium, and then to lipid-soluble organic selenium, each step is optimized for a specific type of organic selenium, not only improving the total extraction rate but also significantly enhancing the purity of the final product, ensuring the comprehensiveness and efficiency of the extraction; the entire extraction process strictly controls key parameters such as temperature, pH value, and ultrasonic power to ensure operation at low temperature (10 - 15°C) and mild conditions, avoiding the destruction of organic selenium by high temperature, strong acids or bases, or intense mechanical action. By using a buffer solution to adjust the pH value to 6.5 - 7.0 and adopting a moderate ultrasonic power (50 - 150W), the structural integrity and biological activity of organic selenium are effectively protected, making the final product have higher application value, especially in the fields of functional foods, health products, and pharmaceutical raw materials, etc.; a variety of environmentally friendly and energy-saving technical means are adopted, which conform to the principles of green chemistry. Water and low-concentration ethanol are preferentially used as extraction solvents, reducing the usage amount of organic solvents and the discharge of waste; through rotary evaporation concentration and freeze-drying technology, most of the solvents can be effectively removed, facilitating the subsequent solvent recovery and reuse, saving resources. In addition, low-temperature treatment and moderate ultrasonic power further reduce energy consumption, reducing energy consumption and achieving a double improvement in environmental protection and economic benefits; the step-by-step extraction method simplifies the production process and improves production efficiency. By preliminary filtration and centrifugal separation, the generation of solid residues is reduced, and the difficulty of subsequent purification is lowered. The combined mixed solution can be directly purified after rotary evaporation concentration, shortening the entire extraction cycle, ensuring the simplicity and repeatability of the operation, being suitable for large-scale industrial production, and bringing significant economic benefits to enterprises.

[0047] The above has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited by the above embodiments. What is described in the above embodiments and the specification only illustrates the principles of the present invention. Without departing from the spirit and scope of the present invention, the present invention will have various changes and improvements, and these changes and improvements all fall within the scope of the present invention claimed. The scope of protection claimed by the present invention is defined by the appended claims and their equivalents.

Claims

1. A method for stepwise extraction of organic selenium in natural selenium-rich agricultural products, characterized in that: It includes the following steps: S1: Clean the natural selenium-rich agricultural products, dry them after removing impurities, crush and sieve the dried natural selenium-rich agricultural products to obtain fine powder; S2: Add the crushed raw materials to an aqueous solution containing a buffer in a ratio of 1:10 w / v, adjust the pH value to 6.5 - 7.0, perform ultrasonic treatment to obtain a mixed system A, then transfer it to a refrigerated centrifuge for centrifugation, separate the precipitate after centrifugation to obtain an extractive solution a containing water-soluble organic selenium in the aqueous phase and a precipitate a; S3: Perform ultrasonic treatment on the precipitate a with low-concentration ethanol to obtain a mixed system B, separate the precipitate after centrifugation to obtain an extractive solution b containing hydrophilic and hydrophobic organic selenium and a precipitate b; S4: Perform ultrasonic treatment on the precipitate b with a high-concentration organic solvent in the same manner as the above steps to obtain a mixed system C, separate the precipitate after centrifugation to obtain an extractive solution c containing liposoluble organic selenium and a precipitate c; S5: Combine the above-obtained extractive solution a containing water-soluble organic selenium in the aqueous phase, extractive solution b containing hydrophilic and hydrophobic organic selenium, and extractive solution c containing liposoluble organic selenium to obtain a mixed solution containing different types of organic selenium compounds, perform rotary evaporation and concentration under low-temperature conditions of 35 - 40 °C, and purify the concentrated extract to obtain organic selenium compounds.

2. The step-by-step extraction method of organic selenium in a natural selenium-rich agricultural product according to claim 1, wherein: In the said S1, the drying temperature is 35 - 40 °C, and the crushed natural selenium-rich agricultural products are sieved through a 120-mesh sieve.

3. The stepwise extraction method of organic selenium in a natural selenium-rich agricultural product according to claim 1, characterized in that: In the said S2, the buffer is selected from any one of phosphate buffer solution and Tris-HCl buffer solution.

4. The step-by-step extraction method of organic selenium in a natural selenium-rich agricultural product according to claim 1, characterized in that: In the said S2, ultrasonic treatment is performed under low-temperature conditions of 10 - 15 °C, the treatment duration is 15 - 30 min, the ultrasonic frequency is 20 - 40 kHz, and the ultrasonic power is 50 - 150 W.

5. The step-by-step extraction method of organic selenium in a natural selenium-rich agricultural product according to claim 1, characterized in that: In the said S2, the centrifugation speed is 4000 - 5000 rpm, and the centrifugation duration is 10 - 15 min.

6. The step-by-step extraction method of organic selenium in a natural selenium-rich agricultural product according to claim 1, characterized in that: In the said S3, the specific steps are: S301: Add the precipitate a to low-concentration ethanol in a ratio of 1:10 w / v, gently stir evenly, place the mixture in an ultrasonic cleaner, and perform ultrasonic treatment for 15 - 30 min under low-temperature conditions of 10 - 15 °C to obtain a mixed system B; S302: Transfer the mixed system B to a refrigerated centrifuge, centrifuge at a speed of 4000 - 5000 rpm for 8 - 12 min, separate the precipitate after centrifugation to obtain an extractive solution b containing hydrophilic and hydrophobic organic selenium and a precipitate b.

7. A method for stepwise extraction of organic selenium in natural selenium-rich agricultural products according to claim 6, characterized in that: In the said S301, the ultrasonic frequency and ultrasonic power of the ultrasonic treatment are the same as those of the ultrasonic treatment in S2.

8. The step-by-step extraction method of organic selenium in a natural selenium-rich agricultural product according to claim 6, characterized in that: In the said S301, the low-concentration ethanol is an ethanol solution with a concentration of 20 - 35%.

9. The step-by-step extraction method of organic selenium in a natural selenium-rich agricultural product according to claim 1, characterized in that: In the said S4, the high-concentration organic solvent is selected from any one of acetone with a concentration of 80 - 100% and methanol with a concentration of 80 - 100%.

10. The stepwise extraction method of organic selenium in a natural selenium-rich agricultural product according to claim 1, characterized in that: In the said S5, before concentrating the mixed solution, it further includes: preliminarily filtering the combined mixed solution with a microporous filter membrane.

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