Method for separating stevioside and chlorogenic acid

Abstract

The invention discloses a method for separating stevioside and chlorogenic acid, which comprises the following steps: concentrating a stevia rebaudiana extracting solution by using a nanofiltration membrane to obtain a concentrated solution; the concentrated solution is adsorbed through a resin system formed by connecting LX-8 and LX-T28 resin columns in series, after adsorption is finished, the LX-8 resin column is independently analyzed through a 60-80 wt% ethanol solution, a chlorogenic acid analysis solution is obtained, the LX-28 resin column is analyzed through a 60-80 wt% ethanol solution, and a stevioside analysis solution is obtained; concentrating the chlorogenic acid desorption solution, and performing spray drying to obtain chlorogenic acid; and concentrating the stevioside desorption solution, and performing spray drying to obtain the stevioside. According to the method, the stevia rebaudiana extracting solution is taken as a raw material, the concentrated stevia rebaudiana extracting solution is treated by adopting a serial resin system, stevioside and chlorogenic acid in the stevia rebaudiana extracting solution are respectively adsorbed and separated by utilizing different adsorption resins, and the method is simple and high in separation efficiency.

Description

Technical Field

[0001] The invention relates to the technical field of stevioside, and in particular to a method for separating stevioside and chlorogenic acid. Background Art

[0002] The main component of stevia dry leaves is steviol glycoside, which is not only sweet and low in calories, but also has certain pharmacological effects. Stevioside mainly has the effects of treating diabetes, controlling blood sugar, lowering blood pressure, anti-tumor, anti-diarrhea, improving immunity, and promoting metabolism. It has a good effect on controlling obesity, regulating gastric acid, and restoring nerve fatigue. It also has significant therapeutic effects on heart disease and pediatric dental caries. The most important thing is that it can eliminate the side effects of sucrose. In addition. The extract obtained when using stevia to extract stevioside also contains a certain amount of chlorogenic acid. Chlorogenic acid has antioxidant, anti-inflammatory, antibacterial, antiviral effects, and anti-hyperglycemia and hyperlipidemia. Therefore, it is of great significance to use stevia to simultaneously extract and separate stevioside and chlorogenic acid.

[0003] Chinese patent 201811159815.9 discloses an industrial method for the simultaneous preparation of stevia chlorogenic acid and steviol glycosides, using stevia as raw material, after alcohol extraction, adjusting the liquid state so that chlorogenic acid is in a free molecule state, and extracting and separating with a medium-polar organic solvent that is immiscible with water, the organic layer is enriched with stevia chlorogenic acid, and the water layer is enriched with steviol glycosides. The above method has the following disadvantages: low production efficiency, low product yield, high production cost, and a large amount of extraction solvent is used in the process.

[0004] Chinese patent 201210421968.2 discloses a method for preparing stevioside and chlorogenic acid from stevia leaves in steps, specifically: adding divalent iron salt to stevia extract for flocculation precipitation, precipitating chlorogenic acid in the extract, adsorbing, analyzing and refining the filtrate with macroporous adsorption resin to obtain stevioside, adding water to the filter cake to dissolve, adsorbing, analyzing, concentrating, drying and recrystallizing with macroporous adsorption resin to obtain chlorogenic acid. The above method has the following disadvantages: the process is complicated and the separation effect still needs to be further improved. Summary of the invention

[0005] The technical problem to be solved by the present invention is: in view of the deficiencies in the prior art, a method for separating stevioside and chlorogenic acid is provided. The present invention uses stevioside extract as a raw material, adopts a series of resin systems to treat the concentrated stevioside extract, and uses different adsorption resins to respectively adsorb and separate stevioside and chlorogenic acid in the stevioside extract. The above method is simple and has high separation efficiency.

[0006] In order to solve the above technical problems, the technical solution of the present invention is:

[0007] A method for separating stevioside and chlorogenic acid comprises the following steps:

[0008] (1) concentrating the stevia extract using a nanofiltration membrane to obtain a concentrated solution;

[0009] (2) The concentrated solution is adsorbed by a resin system consisting of LX-8 and LX-T28 resin columns connected in series. After the adsorption, the LX-8 resin column is analyzed using a 60-80 wt % ethanol solution to obtain a chlorogenic acid analysis solution, and the LX-28 resin column is analyzed using a 60-80 wt % ethanol solution to obtain a stevioside analysis solution;

[0010] (3) The chlorogenic acid analysis solution is concentrated and then spray-dried to obtain chlorogenic acid; the stevioside analysis solution is concentrated and then spray-dried to obtain stevioside.

[0011] Preferably, the preparation method of the stevia extract is: using an ethanol solution with a concentration of 10-60wt% as an extraction solvent, performing countercurrent extraction on stevia powder, and the mass ratio of the ethanol solution to the stevia powder is 10-20:1.

[0012] Preferably, in step (1), the molecular weight cutoff of the nanofiltration membrane is 1000-2000Da, and the stevia extract is concentrated to 1 / 3-1 / 5 of the stevia extract.

[0013] The solid content of the solution will affect the subsequent resin separation effect. If the solid content is too high, the separation will be insufficient, while if the solid content is too low, the sample volume will be too large, affecting the adsorption efficiency. Therefore, the stevia extract is concentrated to an appropriate solid content through a nanofiltration membrane.

[0014] Preferably, in step (2), the ratio of the number of LX-8 and LX-T28 resin columns in the resin system is 1:4. When preparing the stevioside analytical solution, a 60-80wt% ethanol solution is used to parse the first two LX-T28 resin columns connected in series. In the next round of feeding, LX-8 is used as the first column of the resin system, and the third column LX-T28 and the fourth column LX-T28 of the previous round are used as the first column LX-T28 and the second column LX-T28 of this round, and so on, in a reciprocating cycle.

[0015] According to the content of chlorogenic acid and stevioside in stevia extract and the adsorption capacity of the resin, the resin system includes a series of LX-8 resin columns and 4 LX-T28 resin columns. During separation, when the LX-T28 tail column produces sweetness, the LX-8 resin adsorption is near saturation, and the first two columns of LX-T28 adsorption are saturated. At this time, the LX-8 resin is analyzed by ethanol solution alone to obtain chlorogenic acid analysis solution, and the first two columns of LX-T28 are analyzed by ethanol solution to obtain stevioside analysis solution; after the analysis is completed, when the next round of feeding is carried out, LX-8 is still used as the first column of the resin system, the third column LX-T28 of the previous round is used as the first column LX-T28 of this round, and the fourth column LX-T28 of the previous round is used as the second column LX-T28 of this round, and so on. The reciprocating cycle can achieve the separate adsorption of chlorogenic acid and stevioside with one feeding.

[0016] Preferably, in step (2), when preparing the chlorogenic acid analysis solution, the volume of the ethanol solution is 1.5-2BV of the resin column volume, and when preparing the stevioside analysis solution, the volume of the ethanol solution is 1.5-2BV of the resin volume.

[0017] Preferably, in step (2), the flow rate during sample adsorption and analysis is 1-1.5 BV / h.

[0018] Preferably, in step (2), the stevioside solution is purified before concentration, and the purification process comprises adding an adsorbent to the stevioside solution for adsorption treatment, followed by filtering, eluting the filtered precipitate with a hydrochloric acid solution, and collecting the eluate.

[0019] Preferably, the preparation method of the adsorbent is: adding SDS to a mixed solution of p-toluenesulfonic acid, 2,6-diaminoanthraquinone and tetrahydrofuran, stirring and mixing, adding water, stirring at room temperature, adding a tetrahydrofuran solution of 1,3,5-triformylphloroglucinol, continuing to stir the reaction, drying after the reaction is completed, centrifuging the reaction solution, washing the centrifugal precipitate and drying to obtain an SDS-modified COFs skeleton material.

[0020] Preferably, the mass ratio of SDS, p-toluenesulfonic acid, 2,6-diaminoanthraquinone and 1,3,5-triformylphloroglucinol is (0.05-0.1):(0.1-0.15):(0.8-0.9):0.6.

[0021] Preferably, the stirring time at room temperature is 20-30 min, the rotation speed is 400-500 r / min, and the stirring reaction time is 7-8 h.

[0022] Preferably, the addition amount of the SDS-modified COFs skeleton material is 0.02-0.05% of the mass of the stevia analytical solution, the stirring speed of the stirring adsorption treatment is 400-500 r / min, and the time is 5-6 h.

[0023] Preferably, the concentration of the hydrochloric acid solution is 4-5wt%, and the mass ratio of the hydrochloric acid solution to the precipitate during elution is (5-10):1.

[0024] Due to the adoption of the above technical solution, the beneficial effects of the present invention are:

[0025] 1. The present invention provides a method for separating stevioside and chlorogenic acid. The method uses LX-8 and LX-T28 resins as adsorption resins, utilizes the effects of the resins with chlorogenic acid and stevioside, and respectively adsorbs and separates chlorogenic acid and stevioside. The process route is simple, multiple extractions are not required, and the method is safe, simple, and efficient.

[0026] 2. The resin system used in the present invention is a series of LX-8 and LX-T28 resin columns. The quantity ratio of LX-8 and LX-T28 resin columns is controlled to be 1:4 by the content of chlorogenic acid and stevioside in the stevia extract. During the adsorption treatment, when the LX-T28 tail column produces sweetness, the LX-8 resin column and part of the LX-T28 resin column are saturated with adsorption, and then a certain concentration of ethanol solution is used to separately analyze the LX-8 resin column and part of the LX-T28 resin column; during the next adsorption, the feed of multiple LX-T28 resin columns is adjusted by switching the valve, thereby realizing continuous adsorption treatment with high efficiency and high product yield.

[0027] 3. The present invention further purifies the stevioside solution after resin analysis. During the purification, SDS-modified COFs skeleton material is used, which can effectively adsorb stevioside in the analysis solution through hydrogen bonding. Then, a certain hydrochloric acid solution is used for elution, which further improves the purity of stevioside. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 It is a structural schematic diagram of the resin system;

[0029] In the figure, 1, LX-8 resin column; 2, the first LX-T28 resin column; 3, the second LX-T28 resin column; 4, the third LX-T28 resin column; 5, the fourth LX-T28 resin column. DETAILED DESCRIPTION

[0030] In order to more clearly understand the above-mentioned objectives, features and advantages of the present invention, the scheme of the present invention will be further described below. It should be noted that the embodiments of the present invention and the features in the embodiments can be combined with each other without conflict.

[0031] In order to further understand the present invention, preferred embodiments of the present invention are described below in conjunction with examples. However, it should be understood that these descriptions are only for further illustrating the features and advantages of the present invention, rather than limiting the claims of the present invention.

[0032] In the following examples and comparative examples, the preparation method of stevia extract is as follows: 1 kg of stevia plant leaves are crushed and mixed with a 20 wt % solution at a mass ratio of 1:20, and countercurrent extraction is performed at 40° C. for 2 hours to obtain a stevia extract; the content of chlorogenic acid in the extract is 2.1 wt %, and the content of steviol glycoside is 27.3 wt %.

[0033] like Figure 1 As shown, the resin system in the following embodiments and comparative examples is: comprising an LX-8 resin column 1, a first LX-T28 resin column 2, a second LX-T28 resin column 3, a third LX-T28 resin column 4, and a fourth LX-T28 resin column 5 connected in series in sequence.

[0034] In the following examples and comparative examples, the yield calculation method of the product is as follows:

[0035] Chlorogenic acid (%) = [(chlorogenic acid product output × chlorogenic acid content in chlorogenic acid product) / (stevia extract mass × chlorogenic acid content in stevia extract)] × 100%;

[0036] Stevioside (%) = [(stevioside product output × total glycoside content in the steviol glycoside product) / (stevioside extract mass × steviol glycoside content in the stevioside extract)] × 100%.

[0037] Example 1

[0038] A method for separating stevioside and chlorogenic acid comprises the following steps:

[0039] (1) using a nanofiltration membrane with a molecular weight cutoff of 1000 Da to concentrate 1 L of stevia extract to 1 / 5 of the volume of the original solution to obtain a concentrated solution;

[0040] (2) The concentrated solution is pumped into the resin system at a flow rate of 1BV / h for adsorption treatment. When the tail column produces sweetness, the process is stopped. Then, a 60wt% ethanol solution is used to analyze the LX-8 resin column alone at a flow rate of 1BV / h. The volume of the ethanol solution is controlled to be 1.5BV of the volume of the LX-8 resin column to obtain a chlorogenic acid analysis solution. A 60wt% ethanol solution is used to analyze the first LX-T28 resin column and the second LX-T28 resin column connected in series at a flow rate of 1BV / h to obtain a stevioside analysis solution. In the next round of adsorption separation, the LX-8 resin column, the third LX-T28 resin column, the fourth LX-T28 resin column, the first LX-T28 resin column, and the second LX-T28 resin column are connected in series in sequence by switching the valve, and the cycle is repeated.

[0041] (3) The chlorogenic acid analysis solution was concentrated and then spray-dried to obtain 46.5 g of chlorogenic acid product, with a total chlorogenic acid content of 40.9 wt % and a chlorogenic acid yield of 90.5%; the above stevioside analysis solution was concentrated and then spray-dried to obtain 274.7 g of stevioside product, with a total glycoside content of 98.3 wt % and a yield of 98.9%.

[0042] Example 2

[0043] A method for separating stevioside and chlorogenic acid comprises the following steps:

[0044] (1) using a nanofiltration membrane with a molecular weight cutoff of 2000 Da to concentrate 1 L of stevia extract to 1 / 5 of the volume of the original solution to obtain a concentrated solution;

[0045] (2) The concentrated solution was pumped into the resin system at a flow rate of 1.5 BV / h for adsorption treatment. When the tail column produced sweetness, the process was stopped. Then, a 60 wt% ethanol solution was used to analyze the LX-8 resin column alone at a flow rate of 1.5 BV / h. The volume of the ethanol solution was controlled to be 2 BV of the volume of the LX-8 resin column to obtain a chlorogenic acid analysis solution. A 60 wt% ethanol solution was used to analyze the first LX-T28 resin column and the second LX-T28 resin column connected in series at a flow rate of 1.5 BV / h to obtain a stevioside analysis solution. In the next round of adsorption separation, the LX-8 resin column, the third LX-T28 resin column, the fourth LX-T28 resin column, the first LX-T28 resin column, and the second LX-T28 resin column were connected in series in sequence by switching the valve, and the cycle was repeated.

[0046] (3) The chlorogenic acid solution was concentrated and spray-dried to obtain 46.7 g of chlorogenic acid, with a total chlorogenic acid content of 40.5 wt % and a yield of 90.1%;

[0047] (4) Add 0.05 g SDS to a mixed solution of 0.11 g p-toluenesulfonic acid, 0.8 g 2,6-diaminoanthraquinone and 2 ml tetrahydrofuran, stir and mix, add 4.5 ml water, stir at room temperature for 30 min at a speed of 500 r / min, add a tetrahydrofuran solution containing 0.6 g 1,3,5-triformylphloroglucinol, continue stirring and react for 7 h, dry after the reaction is completed, centrifuge the reaction solution, wash the centrifugal precipitate and dry it to obtain SDS-modified COFs framework material;

[0048] (5) Add SDS-modified COFs skeleton material to the above stevioside analysis solution (the added amount is 0.03% of the mass of the stevioside analysis solution), stir and adsorb for 5 hours at 400 r / min, then filter, and elute the filtered precipitate with a 5wt% hydrochloric acid solution (the mass ratio of the hydrochloric acid solution to the precipitate is 5:1), collect the eluate, concentrate the eluate and spray dry it to obtain 273.6g of stevioside with a total glycoside content of 99.0wt% and a yield of 99.2%.

[0049] Example 3

[0050] A method for separating stevioside and chlorogenic acid comprises the following steps:

[0051] (1) using a nanofiltration membrane with a molecular weight cutoff of 2000 Da to concentrate 1 L of stevia extract to 1 / 5 of the volume of the original solution to obtain a concentrated solution;

[0052] (2) The concentrated solution was pumped into the resin system at a flow rate of 1.2 BV / h for adsorption treatment. When the tail column produced sweetness, the process was stopped. Then, a 60 wt% ethanol solution was used to analyze the LX-8 resin column alone at a flow rate of 1.2 BV / h. The volume of the ethanol solution was controlled to be 1.5 BV of the volume of the LX-8 resin column to obtain a chlorogenic acid analysis solution. A 60 wt% ethanol solution was used to analyze the first LX-T28 resin column and the second LX-T28 resin column connected in series at a flow rate of 1.5 BV / h to obtain a stevioside analysis solution. In the next round of adsorption separation, the LX-8 resin column, the third LX-T28 resin column, the fourth LX-T28 resin column, the first LX-T28 resin column, and the second LX-T28 resin column were connected in series in sequence by switching the valve, and the cycle was repeated.

[0053] (3) The chlorogenic acid solution was concentrated and spray-dried to obtain 46.7 g of chlorogenic acid with a chlorogenic acid content of 40.5 wt % and a yield of 90.1%;

[0054] (4) Add 0.07 g SDS to a mixed solution of 0.1 g p-toluenesulfonic acid, 0.8 g 2,6-diaminoanthraquinone and 2 ml tetrahydrofuran, stir and mix, add 4.5 ml water, stir at room temperature at a speed of 400-500 r / min for 20 min, add a tetrahydrofuran solution containing 0.6 g 1,3,5-triformylphloroglucinol, continue stirring and react for 7 h, dry after the reaction is completed, centrifuge the reaction solution, wash the centrifugal precipitate and dry it to obtain SDS-modified COFs framework material;

[0055] (5) Add SDS-modified COFs skeleton material to the above stevioside analysis solution (the added amount is 0.04% of the mass of the stevioside analysis solution), stir and adsorb for 5 hours at 400 r / min, then filter, and elute the filtered precipitate with a 5wt% hydrochloric acid solution (the mass ratio of the hydrochloric acid solution to the precipitate is 6:1), collect the eluate, concentrate the eluate and spray dry it to obtain 273.7g of stevioside with a total glycoside content of 99.1wt% and a yield of 99.4%.

[0056] Example 4

[0057] A method for separating stevioside and chlorogenic acid comprises the following steps:

[0058] (1) using a nanofiltration membrane with a molecular weight cutoff of 1000 Da to concentrate 1 L of stevia extract to 1 / 5 of the volume of the original solution to obtain a concentrated solution;

[0059] (2) The concentrated solution was pumped into the resin system at a flow rate of 1.5 BV / h for adsorption treatment. When the tail column produced sweetness, the process was stopped. Then, a 60 wt% ethanol solution was used to analyze the LX-8 resin column alone at a flow rate of 1.5 BV / h. The volume of the ethanol solution was controlled to be 2 BV of the volume of the LX-8 resin column to obtain a chlorogenic acid analysis solution. A 60 wt% ethanol solution was used to analyze the first LX-T28 resin column and the second LX-T28 resin column connected in series at a flow rate of 1 BV / h to obtain a stevioside analysis solution. In the next round of adsorption separation, the LX-8 resin column, the third LX-T28 resin column, the fourth LX-T28 resin column, the first LX-T28 resin column, and the second LX-T28 resin column were connected in series in sequence by switching the valve, and the cycle was repeated.

[0060] (3) The chlorogenic acid solution was concentrated and spray-dried to obtain 45.9 g of chlorogenic acid with a chlorogenic acid content of 41.3 wt % and a yield of 90.3%;

[0061] (4) Add 0.05 g SDS to a mixed solution of 0.1 g p-toluenesulfonic acid, 0.8 g 2,6-diaminoanthraquinone and 2 ml tetrahydrofuran, stir and mix, add 4.5 ml water, stir at room temperature for 30 min at a speed of 500 r / min, add a tetrahydrofuran solution containing 0.6 g 1,3,5-triformylphloroglucinol, continue stirring and react for 8 h, dry after the reaction is completed, centrifuge the reaction solution, wash the centrifugal precipitate and dry it to obtain SDS-modified COFs framework material;

[0062] (5) Add SDS-modified COFs skeleton material to the above stevioside analysis solution (the added amount is 0.04% of the mass of the stevioside analysis solution), stir and adsorb for 6 hours at 500 r / min, then filter, and elute the filtered precipitate with a 5wt% hydrochloric acid solution (the mass ratio of the hydrochloric acid solution to the precipitate is 7:1), collect the eluate, concentrate the eluate and spray dry it to obtain 273.8g of stevioside with a total glycoside content of 98.9wt% and a yield of 99.2%.

[0063] Example 5

[0064] A method for separating stevioside and chlorogenic acid comprises the following steps:

[0065] (1) using a nanofiltration membrane with a molecular weight cutoff of 1000 Da to concentrate 1 L of stevia extract to 1 / 5 of the volume of the original solution to obtain a concentrated solution;

[0066] (2) The concentrated solution was pumped into the resin system at a flow rate of 1.5 BV / h for adsorption treatment. When the tail column produced sweetness, the process was stopped. Then, a 60 wt% ethanol solution was used to analyze the LX-8 resin column alone at a flow rate of 1.3 BV / h. The volume of the ethanol solution was controlled to be 2 BV of the volume of the LX-8 resin column to obtain a chlorogenic acid analysis solution. A 60 wt% ethanol solution was used to analyze the first LX-T28 resin column and the second LX-T28 resin column connected in series at a flow rate of 1.5 BV / h to obtain a stevioside analysis solution. In the next round of adsorption separation, the LX-8 resin column, the third LX-T28 resin column, the fourth LX-T28 resin column, the first LX-T28 resin column, and the second LX-T28 resin column were connected in series in sequence by switching the valve, and the cycle was repeated.

[0067] (3) The chlorogenic acid solution was concentrated and spray-dried to obtain 46.9 g of chlorogenic acid with a chlorogenic acid content of 40.5 wt % and a yield of 90.5%;

[0068] (4) Add 0.08 g SDS to a mixed solution of 0.1 g p-toluenesulfonic acid, 0.8 g 2,6-diaminoanthraquinone and 2 ml tetrahydrofuran, stir and mix, add 4.5 ml water, stir at room temperature for 30 min at a speed of 400 r / min, add a tetrahydrofuran solution containing 0.6 g 1,3,5-triformylphloroglucinol, continue stirring and react for 8 h, dry after the reaction is completed, centrifuge the reaction solution, wash the centrifugal precipitate and dry it to obtain SDS-modified COFs framework material;

[0069] (5) Add SDS-modified COFs skeleton material to the above stevioside analysis solution (the added amount is 0.04% of the mass of the stevioside analysis solution), stir and adsorb for 5 hours at 400 r / min, then filter, and elute the filtered precipitate with a 5wt% hydrochloric acid solution (the mass ratio of the hydrochloric acid solution to the precipitate is 8:1), collect the eluate, concentrate the eluate and spray dry it to obtain 273.8g of stevioside with a total glycoside content of 98.8wt% and a yield of 99.1%.

[0070] In order to further illustrate the effect of the present invention, a detailed description is given below in conjunction with a plurality of comparative examples.

[0071] Comparative Example 1

[0072] Compared with Example 1, the difference is that in step (1), the solution is concentrated to 1 / 6 of the original solution volume, and the other conditions are the same as those in Example 1, to obtain 55.3 g of chlorogenic acid, with a total chlorogenic acid content of 31.2 wt %, and a yield of 82.2%, and 278.9 g of stevioside, with a total glycoside content of 84.9 wt %, and a yield of 86.7%.

[0073] Comparative Example 2

[0074] Compared with Example 1, the difference is that in step (2), the flow rate of the concentrated liquid during feeding is 2BV / h, and the other conditions are the same as those in Example 1, and 40.2 g of chlorogenic acid is obtained, with a total chlorogenic acid content of 40.5 wt%, a yield of 77.5%, and 270.4 g of stevioside, with a total glycoside content of 98.1 wt%, and a yield of 97.2%.

[0075] Comparative Example 3

[0076] Compared with Example 1, the difference is that in step (2), when preparing the chlorogenic acid analytical solution and the stevioside analytical solution, the flow rate of the ethanol solution is 2BV / h, and the other conditions are the same as those in Example 1, and 38.5g of chlorogenic acid is obtained, with a total chlorogenic acid content of 40.7wt%, and a yield of 74.6%, and 265.7g of stevioside is obtained, with a total glycoside content of 98.5wt%, and a yield of 95.9%.

[0077] Comparative Example 4

[0078] Compared with Example 2, the difference is that in step (4), SDS is not added, and the other conditions are the same as those in Example 2, and 46.3 g of chlorogenic acid is obtained, with a total chlorogenic acid content of 41.0 wt %, and a yield of 90.4%; 264.3 g of stevioside is obtained, with a total glycoside content of 98.7 wt %, and a yield of 95.6%.

[0079] Comparative Example 5

[0080] Compared with Example 2, the difference is that in step (4), the amount of SDS added is 0.01 g, and the other conditions are the same as those in Example 2, and 46.6 g of chlorogenic acid is obtained, with a total chlorogenic acid content of 40.8 wt %, and a yield of 90.5%, and 265.2 g of stevioside is obtained, with a total glycoside content of 98.8 wt %, and a yield of 96.0%.

[0081] Comparative Example 6

[0082] Compared with Example 2, the difference is that in step (4), the amount of SDS added is 0.5 g, and the other conditions are the same as those in Example 2, and 46.5 g of chlorogenic acid is obtained, with a total chlorogenic acid content of 40.9 wt %, and a yield of 90.6%, and 273.9 g of stevioside is obtained, with a total glycoside content of 99.1 wt %, and a yield of 99.4%.

[0083] In summary, the present invention adopts a resin system composed of LX-8 and LX-T28 resin columns connected in series to perform adsorption separation on stevia extract, and combines membrane concentration technology to reasonably adjust the separation and concentration conditions to obtain stevioside and chlorogenic acid with high yield and high purity.

[0084] Specific examples are used herein to illustrate the principles and implementation methods of the present invention. The description of the above embodiments is only used to help understand the method of the present invention and its core ideas, including the best mode, and also enable any technician in the field to practice the present invention, including making and using any device or system, and implementing any combined method. It should be pointed out that for ordinary technicians in this technical field, without departing from the principle of the present invention, the present invention can also be improved and modified, and these improvements and modifications also fall within the scope of protection of the claims of the present invention. The scope of patent protection of the present invention is defined by the claims and may include other embodiments that can be thought of by those skilled in the art. If these other embodiments have structural elements similar to the literal expression of the claims, or if they include equivalent structural elements that are not substantially different from the literal expression of the claims, then these other embodiments should also be included in the scope of the claims.

Claims

1. A method for separating stevioside and chlorogenic acid, characterized in that: The following steps are involved: (1) concentrating the stevia extract using a nanofiltration membrane to obtain a concentrated solution; (2) The concentrated solution is adsorbed by a resin system consisting of LX-8 and LX-T28 resin columns connected in series. After the adsorption, the LX-8 resin column is analyzed using a 60-80 wt % ethanol solution to obtain a chlorogenic acid analysis solution, and the LX-28 resin column is analyzed using a 60-80 wt % ethanol solution to obtain a stevioside analysis solution; (3) The chlorogenic acid analysis solution is concentrated and then spray-dried to obtain chlorogenic acid; the stevioside analysis solution is concentrated and then spray-dried to obtain stevioside.

2. The method for separating stevioside and chlorogenic acid according to claim 1, characterized in that: In step (1), the preparation method of the stevia extract is: using an ethanol solution with a concentration of 10-60wt% as an extraction solvent, countercurrent extraction is performed on stevia powder, and the mass ratio of the ethanol solution to the stevia powder is 10-20:

1.

3. The method for separating stevioside and chlorogenic acid according to claim 1, characterized in that: In step (1), the molecular weight cutoff of the nanofiltration membrane is 1000-2000Da, and the stevia extract is concentrated to 1 / 3-1 / 5 of the stevia extract.

4. The method for separating stevioside and chlorogenic acid according to claim 1, characterized in that: In step (2), the ratio of the number of LX-8 and LX-T28 resin columns in the resin system is 1:

4. When preparing the stevioside analytical solution, a 60-80wt% ethanol solution is used to parse the first two LX-T28 resin columns connected in series. In the next round of feeding, LX-8 is used as the first column of the resin system, and the third column LX-T28 and the fourth column LX-T28 of the previous round are used as the first column LX-T28 and the second column LX-T28 of this round, and so on, and the cycle is repeated.

5. The method for separating stevioside and chlorogenic acid according to claim 1, characterized in that: In step (2), when preparing the chlorogenic acid analysis solution, the volume of the ethanol solution is 1.5-2BV of the resin column volume, and when preparing the stevioside analysis solution, the volume of the ethanol solution is 1.5-2BV of the resin volume.

6. The method for separating stevioside and chlorogenic acid according to claim 1, characterized in that: In step (2), the flow rate during sample adsorption and analysis is 1-1.5 BV / h.

7. The method for separating stevioside and chlorogenic acid according to claim 1, characterized in that: In step (2), the stevioside solution is purified before concentration. The purification process includes adding an adsorbent to the stevioside solution for adsorption treatment, followed by filtering, eluting the filtered precipitate with a hydrochloric acid solution, and collecting the eluate.

8. The method for separating stevioside and chlorogenic acid according to claim 7, characterized in that: The preparation method of the adsorbent is as follows: SDS is added to a mixed solution of p-toluenesulfonic acid, 2,6-diaminoanthraquinone and tetrahydrofuran, water is added after stirring and mixing, 1,3,5-triformylphloroglucinol tetrahydrofuran solution is added after stirring at room temperature for 20-30 minutes at a speed of 400-500 r / min, stirring and reacting for 7-8 hours, drying after the reaction is completed, centrifuging the reaction solution, washing the centrifugal precipitate and drying to obtain the SDS-modified COFs skeleton material.

9. The method for separating stevioside and chlorogenic acid according to claim 8, characterized in that: The mass ratio of SDS, p-toluenesulfonic acid, 2,6-diaminoanthraquinone and 1,3,5-triformylphloroglucinol is (0.05-0.1):(0.1-0.15):(0.8-0.9):0.

6.

10. The method for separating stevioside and chlorogenic acid according to claim 7, characterized in that: The addition amount of SDS modified COFs skeleton material is 0.02-0.05% of the mass of stevia analytical solution, and the stirring speed of the stirring adsorption treatment is 400-500r / min, and the time is 5-6h; And / or the concentration of the hydrochloric acid solution is 4-5wt%, and the mass ratio of the hydrochloric acid solution to the precipitate during elution is (5-10):1.

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