A method for extracting bioactive substances from selenium-rich tea

Abstract

The present application relates to the technical field of food processing, and provides a method for extracting bioactive substances from selenium-rich tea, which comprises the following steps: S1. crushing selenium-rich tea leaves, soaking in double-distilled water for a period of time, then placing in a microwave instrument for microwave extraction for a period of time, cooling, filtering, and obtaining a polysaccharide extract; S2. placing the polysaccharide extract in a supercritical carbon dioxide extraction kettle, setting the extraction temperature to 28.3-33.6 DEG C and the extraction pressure to 6.1-8.3 Mpa, and introducing carbon dioxide gas into the supercritical carbon dioxide extraction kettle; after extraction for a period of time, opening a separation kettle connected to the supercritical carbon dioxide extraction kettle, and connecting the separation kettle with a carbon dioxide gas cylinder, continuing to extract for a period of time, and obtaining bioactive substances, which can green, efficient and convenient to extract different bioactive substances from selenium-rich tea in turn and is suitable for industrial production.

Description

Technical Field

[0001] This invention relates to the field of food processing technology, and more specifically, to a method for extracting bioactive substances from selenium-rich tea. Background Technology

[0002] Selenium-enriched tea is a specialty agricultural product of Anhua County, Hunan Province, and a raw material for health foods with clearly defined health benefits, highly favored by consumers both domestically and internationally. Selenium-enriched tea is rich in nutrients, including vitamins, minerals, proteins, amino acids, and sugars. In particular, its selenium content reaches 1500-3000 ug / kg, which is 10-20 times that of ordinary tea.

[0003] Selenium is an essential trace element for maintaining human health and participates in all aspects of human life. Polysaccharides have been proven to enhance immunity, improve glucose metabolism, and have antioxidant functions. Selenium-enriched tea is not only rich in selenium but also contains abundant active ingredients such as selenium-enriched tea polyphenols, selenium-enriched tea polysaccharides, and flavonoids, which have not yet been utilized in a high-value manner, resulting in resource waste. Studies have found that the biological activity of selenium-enriched tea polysaccharides is generally higher than that of polysaccharides and selenium itself. Furthermore, research has demonstrated that selenium-enriched tea polysaccharides have a significant effect on regulating glucose and lipid metabolism.

[0004] There are many existing methods for extracting tea polysaccharides. For example, Chinese Patent CN111587976A discloses a method and application for extracting bioactive components from selenium-rich tea. This method uses ultra-micronized nanotechnology to break down cell walls and vacuum critical point extraction combined with ultrasonic technology, along with enzymatic decomposition, to extract crude protein, polysaccharides, tea polyphenols, and minerals such as selenium. However, on the one hand, the combination of many technologies used in the extraction process makes it difficult to scale up for industrial extraction and significantly increases extraction costs. On the other hand, excessively high temperatures during extraction can cause the degradation of certain heat-sensitive compounds, producing byproducts. Finally, although enzyme-assisted extraction can improve the polysaccharide yield, the operating conditions are harsh, increasing the difficulty of experimental operation and the feasibility of industrial application.

[0005] Therefore, it is particularly important to find a green, efficient, and convenient way to extract bioactive substances from selenium-rich tea and make it suitable for industrial application. Summary of the Invention

[0006] The purpose of this invention is to provide a method for extracting bioactive substances from selenium-rich tea, which can extract different bioactive substances from selenium-rich tea in a green, efficient and convenient manner and is suitable for industrial production.

[0007] The embodiments of the present invention are achieved through the following technical solutions:

[0008] A method for extracting bioactive substances from selenium-enriched tea includes the following steps:

[0009] S1. After crushing the selenium-rich tea leaves, soak them in double-distilled water for 10-15 hours; then place them in a microwave oven for microwave extraction. The pressure is 0.8-1.2 MPa, the water-to-material ratio is 1:18-22, the extraction time is 5-10 minutes, the microwave power is 350-450 W, and after cooling for 20-30 minutes and filtering, the polysaccharide extract is obtained.

[0010] S2. Place the polysaccharide extract and entrainer at an addition ratio of 2-5 g: 100 ml in a supercritical carbon dioxide extraction vessel. The entrainer includes acetone and ethanol at a mass ratio of 3-5:1. Set the extraction temperature to 28.3-33.6℃ and the extraction pressure to 6.1-8.3 MPa. Introduce carbon dioxide gas into the supercritical carbon dioxide extraction vessel. Specifically, for the first 30 minutes after adding the polysaccharide extract, control the carbon dioxide gas flow rate at 5-10 ml / min; for the 30-90 minutes after adding the polysaccharide extract, control the carbon dioxide gas flow rate at 30-60 ml / min; for the last 30-50 minutes of extraction, control the carbon dioxide gas flow rate at 10-20 ml / min. After 30 minutes of extraction, open the separation vessel connected to the supercritical carbon dioxide extraction vessel and connect the separation vessel to the carbon dioxide gas cylinder. Continue extraction for a period of time, then remove the extract from the separation vessel, heat it, and separate the entrainer. The resulting bioactive substance is obtained after separation.

[0011] This invention employs a combination of microwave extraction and supercritical carbon dioxide extraction to synergistically extract bioactive substances from selenium-rich tea, thereby extracting different active substances sequentially and with high yield.

[0012] Microwave extraction utilizes electromagnetic fields to effectively separate tea polysaccharides from the matrix in selenium-enriched tea. When combining microwave and supercritical carbon dioxide extraction technologies to extract bioactive substances from selenium-enriched tea, the dipole molecules in the tea matrix continuously rotate under the influence of high-frequency microwave energy, leading to the breakage of hydrogen bonds. This accelerates the penetration of supercritical carbon dioxide into the tea matrix and promotes the extraction of tea polysaccharides.

[0013] Specifically, the inventors adjusted the extraction pressure and temperature to change the solubility of the tea matrix, allowing for the sequential extraction of components with different solubilities, molecular weights, and boiling points as needed. This separated free proteins and other components, enabling the extraction of bioactive ingredients from the matrix under mild conditions. Finally, when the pressure and temperature returned to normal, the components dissolved in the carbon dioxide fluid immediately separated from the gaseous carbon dioxide in a liquid state dissolved in the absorption liquid, thus achieving the extraction and separation purpose. This made the extraction of bioactive substances faster and more efficient, resulting in a higher extraction rate and a shorter extraction time.

[0014] More importantly, based on the properties of different bioactive substances, the inventors, during supercritical carbon dioxide extraction, not only adjusted the extraction pressure and temperature, but also controlled the flow rate of carbon dioxide gas at different times. This, in conjunction with temperature and pressure, ensured that the bioactive substances dissolved in a carbon dioxide-rich atmosphere. This resulted in a deeper penetration and greater solubility of carbon dioxide into the bioactive substances, providing active sites for dissolution or separation of different bioactive substances. Furthermore, by controlling the flow rate of carbon dioxide gas, the inventors could better address the dissolution and extraction of different bioactive substances, allowing them to be extracted sequentially. This ensured a more stable extraction process, resulting in a higher extraction rate and a shorter extraction time.

[0015] In addition, carbon dioxide fluid is non-toxic, leaves no solvent residue, does not cause environmental pollution, is more economical and environmentally friendly, and can be scaled up to adapt to industrial production.

[0016] Further, in S1, soak in double-distilled water for 10-15 hours; and / or cool for 20-30 minutes.

[0017] Furthermore, in S1, during microwave extraction: the pressure is 0.8-1.2 MPa, the water-to-material ratio is 1:18-22, the extraction time is 5-10 min, and the microwave power is 350-450 W.

[0018] Furthermore, in S2, the extraction temperature is 31.6℃ and the extraction pressure is 7.4 MPa.

[0019] Furthermore, S2 also includes adding an entrainer into the supercritical carbon dioxide extraction vessel, the entrainer comprising acetone and ethanol in a mass ratio of 3-5:1.

[0020] Furthermore, the addition ratio of the polysaccharide extract to the entrainer is 2-5g:100ml.

[0021] Furthermore, in S2, the flow rate of carbon dioxide gas is controlled at 5-10 ml / min for the first 30 minutes after adding the polysaccharide extract; the flow rate of carbon dioxide gas is controlled at 30-60 ml / min for the 30-90 minutes after adding the polysaccharide extract; and the flow rate of carbon dioxide gas is controlled at 10-20 ml / min for the last 30-50 minutes of extraction.

[0022] Furthermore, in S2, the separation vessel is opened 30 minutes after extraction.

[0023] Furthermore, it also includes: (4) Separation: Take out the extract from the separation vessel, then heat it to separate the entrainer, and the bioactive substance is obtained after separation.

[0024] The technical solutions of the embodiments of the present invention have at least the following advantages and beneficial effects:

[0025] 1. This invention uses a combination of microwave extraction and supercritical carbon dioxide extraction to synergistically extract bioactive substances from selenium-rich tea, extracting different active substances sequentially and with high yield; the extraction process is non-toxic, leaves no solvent residue, does not cause environmental pollution, is more economical and environmentally friendly, and can be scaled up to adapt to industrial production.

[0026] 2. This invention adjusts the extraction pressure and temperature to change the solubility of the tea matrix, allowing for the sequential extraction of components with different solubilities, molecular weights, and boiling points as needed. This separates free proteins and other components, and enables the extraction of bioactive ingredients from the matrix under mild conditions. Finally, when the pressure and temperature return to normal, the components dissolved in the carbon dioxide fluid immediately separate from the gaseous carbon dioxide in a liquid state dissolved in the absorption liquid, thus achieving the extraction and separation purpose. This makes the extraction of bioactive substances faster and more efficient, resulting in a higher extraction rate and a shorter extraction time.

[0027] 3. Based on the properties of different bioactive substances, the inventors, during supercritical carbon dioxide extraction, not only adjusted the extraction pressure and temperature but also controlled the flow rate of carbon dioxide gas at different times. This, in conjunction with temperature and pressure, ensured that the bioactive substances dissolved in a carbon dioxide-rich atmosphere. This resulted in a deeper penetration and greater solubility of carbon dioxide into the bioactive substances, providing active sites for dissolution or separation of different bioactive substances. Furthermore, by controlling the flow rate of carbon dioxide gas, the inventors could better address the dissolution and extraction of different bioactive substances, allowing them to be extracted sequentially. This ensured a more stable extraction process, resulting in a higher extraction rate and a shorter extraction time. Detailed Implementation

[0028] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below. Where specific conditions are not specified in the embodiments, conventional conditions or conditions recommended by the manufacturer shall apply. Reagents or instruments whose manufacturers are not specified are all conventional products that can be purchased commercially.

[0029] Example 1

[0030] A method for extracting bioactive substances from selenium-enriched tea includes the following steps:

[0031] S1. After crushing 100g of selenium-rich tea leaves, soak them in double-distilled water for 12 hours; then place them in a microwave oven with a pressure of 1.0MPa, a water-to-material ratio of 1:20, an extraction time of 10 minutes, a microwave power of 400W, and after cooling for 25 minutes and filtering, obtain the polysaccharide extract.

[0032] S2. The polysaccharide extract and entrainer were placed in a supercritical carbon dioxide extraction vessel at a ratio of 4g:100ml. The entrainer consisted of acetone and ethanol in a mass ratio of 3-5:1. The extraction temperature was set to 31.5℃ and the extraction pressure to 7.4MPa. Carbon dioxide gas was introduced into the supercritical carbon dioxide extraction vessel. Specifically, the flow rate of carbon dioxide gas was controlled at 8ml / min for the first 30 minutes after adding the polysaccharide extract; and the flow rate was controlled at [missing information - likely a specific value]. The flow rate of carbon dioxide gas was controlled at 15 ml / min during the last 40 minutes of extraction. After 30 minutes of extraction, the separation vessel connected to the supercritical carbon dioxide extraction vessel was opened and connected to the carbon dioxide gas cylinder. Extraction was continued for a period of time. The extracts in the separation vessel were then taken out one by one, heated, and the entrainer was separated. After separation, the extracts were concentrated and vacuum spray-dried to obtain the bioactive substances, including: 5.68 g of tea polysaccharides, 28.12 g of tea polyphenols, and 2.27 g of tea protein.

[0033] Example 2

[0034] A method for extracting bioactive substances from selenium-enriched tea includes the following steps:

[0035] S1. Crush 100g of selenium-rich tea leaves, soak them in double-distilled water for 10 hours; then place them in a microwave oven with a pressure of 1.2MPa, a water-to-material ratio of 1:18, an extraction time of 5 minutes, a microwave power of 450W, cool for 30 minutes, filter, and obtain a polysaccharide extract.

[0036] S2. The polysaccharide extract and entrainer were placed in a supercritical carbon dioxide extraction vessel at an addition ratio of 2g:100ml. The entrainer consisted of acetone and ethanol in a mass ratio of 3:1. The extraction temperature was set to 28.3℃ and the extraction pressure to 6.1MPa. Carbon dioxide gas was introduced into the supercritical carbon dioxide extraction vessel. Specifically, the flow rate of carbon dioxide gas was controlled at 5ml / min for the first 30 minutes after adding the polysaccharide extract; at 30ml / min for the next 30 minutes; and at 10ml / min for the last 30 minutes. After 30 minutes of extraction, the separation vessel connected to the supercritical carbon dioxide extraction vessel was opened and connected to the carbon dioxide gas cylinder. Extraction was continued for a period of time. The extract in the separation vessel was then removed and heated to separate the entrainer. The resulting bioactive substances were: 5.36g of tea polysaccharide, 27.84g of tea polyphenols, and 2.05g of tea protein.

[0037] Example 3

[0038] A method for extracting bioactive substances from selenium-enriched tea includes the following steps:

[0039] S1. Crush 100g of selenium-rich tea leaves, soak them in double-distilled water for 15 hours; then place them in a microwave oven with a pressure of 0.8MPa, a water-to-material ratio of 1:22, an extraction time of 10 minutes, a microwave power of 350W, cool for 20 minutes, filter, and obtain a polysaccharide extract.

[0040] S2. The polysaccharide extract and entrainer were placed in a supercritical carbon dioxide extraction vessel at an addition ratio of 5g:100ml. The entrainer consisted of acetone and ethanol in a mass ratio of 5:1. The extraction temperature was set to 33.6℃ and the extraction pressure to 8.3MPa. Carbon dioxide gas was introduced into the supercritical carbon dioxide extraction vessel. Specifically, the flow rate of carbon dioxide gas was controlled at 10ml / min for the first 30 minutes after adding the polysaccharide extract; at 60ml / min for the first 90 minutes after adding the polysaccharide extract; and at 20ml / min for the last 50 minutes of extraction. After 30 minutes of extraction, the separation vessel connected to the supercritical carbon dioxide extraction vessel was opened and connected to the carbon dioxide gas cylinder. Extraction was continued for a period of time. The extract in the separation vessel was then removed and heated to separate the entrainer. The bioactive substances obtained after separation were: 5.41g of tea polysaccharide, 27.98g of tea polyphenols, and 2.18g of tea protein.

[0041] Comparative Example 1

[0042] The difference between this comparative example and Example 1 is that the microwave extraction in S1 is replaced by steps B)-C) in CN111587976A. The separated bioactive substances are: 4.11g of tea polysaccharide, 25.25g of tea polyphenol, and 1.55g of tea protein.

[0043] Comparative Example 2

[0044] The difference between this comparative example and Example 1 is that the extraction temperature in S2 is 20°C. The separated bioactive substances are: 3.65g tea polysaccharides, 23.17g tea polyphenols, and 1.42g tea protein.

[0045] Comparative Example 3

[0046] The difference between this comparative example and Example 1 is that the extraction pressure in S2 is 4.5 MPa. The separated bioactive substances are: 3.44 g tea polysaccharides, 23.02 g tea polyphenols, and 1.25 g tea protein.

[0047] Comparative Example 4

[0048] The difference between this comparative example and Example 1 is that the carbon dioxide flow rate in S2 was maintained at 8 ml / min throughout, i.e., the carbon dioxide flow rate was not controlled. The separated bioactive substances were: 1.16 g of tea polysaccharides, 18.57 g of tea polyphenols, and 0.94 g of tea protein.

[0049] Experimental Example 1

[0050] Examples 1-3 and Comparative Examples 1-4 were set as experimental groups 1-7. The yield of bioactive substances extracted after the experiment in experimental groups 1-7 was tested (mass of extracted bioactive substances / mass of tea leaves before the experiment). The experimental results are shown in Table 1.

[0051] Table 1. Yield of bioactive substances in experimental groups 1-7

[0052] extract Tea polysaccharides (%) Tea polyphenols (%) Tea protein (%) Experimental group 1 5.68 28.12 2.27 Experimental group 2 5.36 27.84 2.05 Experimental group 3 5.41 27.98 2.18 Experimental group 4 4.11 25.25 1.55 Experimental group 5 3.65 23.17 1.42 Experimental group 6 3.44 23.02 1.25 Experimental group 7 1.16 18.57 0.94

[0053] As can be seen from the data in Table 1:

[0054] The embodiments of the present invention can sequentially extract bioactive substances from selenium-rich tea, with a high extraction rate and good product quality;

[0055] The different treatment methods used in the pretreatment stage of experimental group 4 and experimental group 1 directly affected the subsequent supercritical extraction. The mechanical method of ultrasonic treatment easily breaks the cell wall but cannot break the internal hydrogen bonds, thereby reducing the penetration of supercritical carbon dioxide into the tea matrix and hindering the extraction of tea polysaccharides.

[0056] Experimental group 5 and experimental group 1 were subjected to the same extraction pressure, but the temperature was lower than the extraction temperature of this invention. Experimental group 6 and experimental group 1 were subjected to the same extraction temperature, but the pressure was lower than the extraction pressure of this invention. However, the final extraction yield of bioactive substances was significantly lower than that of Example 1. This is because the increase in temperature accelerates the thermal motion of molecules, and the increase in pressure increases the density of supercritical carbon dioxide fluid, which improves the contact speed and contact area of ​​supercritical carbon dioxide bioactive components, thereby accelerating the extraction process of bioactive components, increasing the extraction rate, and shortening the extraction time. However, it is not always beneficial to continuously increase the temperature or pressure, because excessive increase in temperature or pressure will cause the density of supercritical carbon dioxide fluid to decrease, resulting in a decrease in the solubility of active components, thereby reducing the extraction rate. In fact, excessively high temperature or pressure may even destroy active substances. Therefore, the inventors creatively derived the extraction temperature and extraction pressure of this invention by combining the component properties of selenium-rich tea and the different extraction processes at different stages and the coordination of the preceding and following processes.

[0057] Compared with experimental group 1, experimental group 7 did not control the carbon dioxide flow rate. As a result, bioactive components with different solubilities could not dissolve in supercritical carbon dioxide fluid at different stages according to their different properties. Consequently, it was difficult to efficiently extract the bioactive components from the extracted precipitate, and other components might even be mixed in, resulting in a reduced extraction rate, longer extraction time, and poor product quality. This was not conducive to the sequential and high-yield extraction of bioactive components with different solubilities.

[0058] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for extracting bioactive substances from selenium-rich tea, characterized in that, Includes the following steps: S1. After crushing the selenium-rich tea leaves, soak them in double-distilled water for a period of time; then place them in a microwave oven for microwave extraction for a period of time, cool and filter to obtain polysaccharide extract; S2. Place the polysaccharide extract in a supercritical carbon dioxide extraction vessel, set the extraction temperature to 28.3-33.6℃ and the extraction pressure to 6.1-8.3 MPa, and introduce carbon dioxide gas into the supercritical carbon dioxide extraction vessel. Specifically, in the first 30 minutes after adding the polysaccharide extract, the flow rate of carbon dioxide gas is controlled at 5-10 ml / min; in the 30-90 minutes after adding the polysaccharide extract, the flow rate of carbon dioxide gas is controlled at 30-60 ml / min; in the last 30-50 minutes of extraction, the flow rate of carbon dioxide gas is controlled at 10-20 ml / min; then open the separation vessel connected to the supercritical carbon dioxide extraction vessel and connect the separation vessel to the carbon dioxide gas cylinder, and continue extraction for a period of time to obtain bioactive substances.

2. The method for extracting bioactive substances from selenium-rich tea according to claim 1, characterized in that, In S1, soak in double-distilled water for 10-15 hours; and / or cool for 20-30 minutes.

3. The method for extracting bioactive substances from selenium-rich tea according to claim 2, characterized in that, In S1, during microwave extraction: the pressure is 0.8-1.2 MPa, the water-to-material ratio is 1:18-22, the extraction time is 5-10 min, and the microwave power is 350-450 W.

4. The method for extracting bioactive substances from selenium-rich tea according to claim 1, characterized in that, In S2, the extraction temperature is 31.5℃ and the extraction pressure is 7.4 MPa.

5. The method for extracting bioactive substances from selenium-rich tea according to claim 1, characterized in that, S2 also includes adding an entrainer into the supercritical carbon dioxide extraction vessel, the entrainer comprising acetone and ethanol in a mass ratio of 3-5:

1.

6. The method for extracting bioactive substances from selenium-rich tea according to claim 5, characterized in that, The ratio of the polysaccharide extract to the entrainer is 2-5g:100ml.

7. The method for extracting bioactive substances from selenium-rich tea according to any one of claims 4-6, characterized in that, In S2, the separation vessel is opened 30 minutes after extraction.

8. The method for extracting bioactive substances from selenium-rich tea according to claim 1, characterized in that, Also includes: S3. Separation: The extract in the separation vessel is taken out and then heated to separate the entrainer. The bioactive substance is obtained after separation.