Method for efficiently preparing chlorogenic acid by using stevia rebaudiana extracting solution

Abstract

The invention discloses a method for efficiently preparing chlorogenic acid by using a stevia rebaudiana extracting solution, which comprises the following steps: concentrating the stevia rebaudiana extracting solution, and adjusting the pH value of the concentrated solution to 5.0-6.5 to obtain a to-be-treated solution; pumping the to-be-treated liquid into a simulated moving bed chromatographic system for separation to obtain a chlorogenic acid phase and a stevioside phase; adjusting the pH value of the chlorogenic acid phase to 3.0-4.5, then sequentially carrying out nanofiltration membrane concentration and thermal concentration, and finally carrying out spray drying to obtain a chlorogenic acid product. According to the method, ethanol extraction, simulated moving bed separation and nanofiltration membrane desalination are combined, the yield of the prepared chlorogenic acid is high, the extraction efficiency is high, the technological process is simple, and the production cost is low. In addition, stevioside is also recycled in the process of preparing the chlorogenic acid.

Description

Technical Field

[0001] The present invention relates to the technical field of stevioside production, and in particular to a method for efficiently preparing chlorogenic acid by utilizing stevia extract. Background Art

[0002] Chlorogenic acid, as an important natural antioxidant and bioactive substance, is widely found in many plants. Stevia not only contains stevioside, which is an ideal natural sweetener with high sweetness and low calories, but also contains beneficial ingredients such as chlorogenic acid. Therefore, it is of great significance to extract chlorogenic acid from stevia to increase the added value of the main product.

[0003] Patent application number 202410639319.2 discloses a method for extracting chlorogenic acid from stevia, wherein stevia leaves are soaked in water as an extractant to obtain an immersion solution, lignin and polyaluminium chloride are added to the immersion solution for flocculation reaction to obtain a column liquid; ion exchange resin is selected for preliminary extraction, the analyzed mixed solution is rotary evaporated, water is added, and it is naturally precipitated; then it is purified with a macroporous adsorption resin, and the analyzed product is dried to obtain a high-content total chlorogenic acid product. Although the above-mentioned prior art can obtain chlorogenic acid, it has low efficiency, and a large amount of wastewater is generated during the production process, and the process is complicated. Therefore, it is of great significance to develop an efficient, economical and large-scale chlorogenic acid extraction process. Summary of the invention

[0004] The technical problem to be solved by the present invention is: in view of the shortcomings of the prior art, a method for efficiently preparing chlorogenic acid using stevia extract is provided. The present invention combines ethanol extraction, simulated moving bed separation and nanofiltration membrane desalination to obtain a high yield of chlorogenic acid, fast extraction efficiency, simple process flow and low production cost. In addition, the present invention also recovers steviol glycosides in the process of preparing chlorogenic acid.

[0005] In order to solve the above technical problems, the technical solution of the present invention is:

[0006] A method for efficiently preparing chlorogenic acid using stevia extract comprises the following steps:

[0007] (1) After concentrating the stevia extract, adjusting the pH of the concentrate to 5.0-6.5 to obtain a solution to be treated;

[0008] (2) pumping the liquid to be treated into a simulated moving bed chromatography system for separation to obtain a chlorogenic acid phase and a stevioside phase;

[0009] (3) adjusting the pH of the chlorogenic acid phase to 3.0-4.5, then sequentially performing nanofiltration membrane concentration, thermal concentration, and finally spray drying to obtain the chlorogenic acid product.

[0010] Preferably, the stevia extract is prepared by extracting stevia powder using ethanol solution as the extraction solution.

[0011] Preferably, during extraction, the concentration of the ethanol solution is 10-40 v / v%, and the mass ratio of stevia powder to the ethanol solution is 1:(5-20).

[0012] Preferably, the temperature during extraction is 30-60° C., the extraction is repeated 2-6 times, the single extraction time is 0.5-2 h, and filtration is performed after each extraction. The filtrates from multiple extractions are combined to obtain an extract.

[0013] Preferably, in step (1), a nanofiltration membrane is used to concentrate the stevia extract, the cut-off molecular weight of the nanofiltration membrane is 200-800Da, the operating pressure is 1.5-3.0MPa, and the temperature is 30-60°C; the solid content of the concentrated solution is 20-35wt%.

[0014] Preferably, in step (1), when nanofiltration membrane is used for concentration, pure water is added to the primary retentate after concentration, and re-concentration is performed to collect the secondary retentate, and the primary permeate and the secondary permeate are combined to obtain an ethanol solution.

[0015] Preferably, the volume ratio of the primary retentate to pure water is (2-3):1.

[0016] Preferably, in step (1), a sodium salt solution or a potassium salt solution is used to adjust the pH value of the concentrated solution; and / or the sodium salt is at least one of NaOH, NaHCO3, and Na2CO3; and / or the concentration of the sodium salt solution is 5-40wt%; and / or the potassium salt is at least one of KOH, KHCO3, and K2CO3; and / or the concentration of the potassium salt solution is 5-40wt%.

[0017] Preferably, in step (2), the chromatographic column of the simulated moving bed chromatographic separation system is filled with sodium-type resin or potassium-type resin; the average particle size of the sodium-type resin or potassium-type resin is 220-320 μm; and / or the diameter-to-height ratio of the single column chromatographic column is 2:1-1.5.

[0018] Preferably, in step (2), the simulated moving bed separation system is eight chromatographic columns connected in series and connected end to end; a cyclic separation process includes cyclic flushing, water flushing, water analysis, and feeding process, water analysis and feeding are carried out simultaneously, and the chlorogenic acid phase is recovered in the water flushing process and the feeding process, and the stevioside phase is recovered in the water analysis process.

[0019] Preferably, in one cycle, the circulating liquid flushing amount is 40-42 v / v% of the volume of the single column chromatographic column, the water flushing amount is 18-20 v / v% of the volume of the single column chromatographic column, the water analysis amount is 25-30 v / v% of the volume of the single column chromatographic column, and the feed amount of the treated liquid is 8-10 v / v% of the volume of the single column chromatographic column.

[0020] Preferably, the conditions for simulated moving bed chromatography separation are: circulating flushing flow rate (Va) is 520-600mL / min, water flushing flow rate (Vb) is 520-650mL / min, water decomposition flow rate (Vc) is 470-600mL / min, feed flow rate (Vd) is 125-240mL / min, circulating flushing time is 10-12.2min, water flushing time is 4.2-5.8min, water decomposition time (feeding time) is 6.3-9.7min, and then switch to the next cycle.

[0021] Preferably, in step (3), the pH adjusting agent used to adjust the chlorogenic acid phase is HCl solution, and the concentration of the HCl solution is 1-3 wt %.

[0022] Preferably, in step (3), when the chlorogenic acid phase is treated with a nanofiltration membrane, the molecular weight cutoff of the nanofiltration membrane is 400-800 Da, the operating pressure is 1.5-3.0 MPa, and the temperature is 30-60° C.; the solid content of the retentate after concentration is 10-25 wt%.

[0023] Preferably, in step (3), the temperature during thermal concentration is 60-80° C., the vacuum degree is -0.06 to -0.1 MPa, and the solid content of the concentrated liquid after concentration is 30-55 wt %.

[0024] Preferably, in step (3), the air inlet temperature during spray drying is 160-190°C, and the air outlet temperature is 70-95°C.

[0025] The stevioside phase recovered in the present invention can be purified and the stevioside product can be recovered by using the method for preparing stevioside in the prior art.

[0026] Due to the adoption of the above technical solution, the beneficial effects of the present invention are:

[0027] 1. The present invention uses stevia as raw material, combines ethanol extraction, simulated moving bed chromatography separation and nanofiltration membrane desalination technology to produce chlorogenic acid products, and has high recovery rate and extraction efficiency, simplifies the process flow, and reduces the production cost of chlorogenic acid. In addition, the present invention also post-treats the stevioside phase in the separation process to obtain steviol glycosides, so that the stevia extract is fully utilized.

[0028] 2. The present invention effectively controls the solid content, pH value and conditions of simulated moving bed chromatography of the liquid to be treated, and the pH of the chlorogenic acid phase obtained by simulated moving bed chromatography separation is effectively adjusted before the next step of treatment, so that the chlorogenic acid phase is more stable and the yield of the obtained chlorogenic acid is high.

[0029] 3. When the present invention uses an ethanol solution to extract stevia leaves, the concentration of the ethanol solution, the amount of the ethanol solution, and the extraction temperature and time are effectively controlled so that the chlorogenic acid and stevioside components in the stevia leaves are fully dissolved, thereby improving the extraction rate.

[0030] 4. When the present invention uses nanofiltration membrane for concentration, pure water is added to the primary retentate after concentration to perform re-concentration treatment, collect the secondary retentate, and combine the primary permeate and the secondary permeate to obtain an ethanol solution, thereby completing the recovery of the ethanol solution. The collected ethanol solution can be prepared and reused in the preparation of stevia extract. DETAILED DESCRIPTION

[0031] 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.

[0032] 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.

[0033] The simulated moving bed chromatography system in the following embodiments and comparative examples is composed of eight chromatographic columns connected in series and connected end to end. The eight chromatographic columns are divided into four zones, namely, zone Z1, zone Z2, zone Z3, and zone Z4, and the above four zones are connected in sequence. In one cycle, the first chromatographic column is zone Z1, zone Z2 is three chromatographic columns connected in series, zone Z3 is three chromatographic columns connected in series, and the last chromatographic column is zone Z4. When switching to the next cycle, by switching the feed and discharge valves, each zone is moved back by one chromatographic column as a whole.

[0034] Specifically, after the system is stable, one cycle includes four processes: circulation flushing, water flushing, water analysis and feeding. Water analysis and feeding are carried out simultaneously. During circulation flushing, the effluent of the chromatographic column in zone Z4 enters from the chromatographic column in zone Z1 to flush the chlorogenic acid in the chromatographic columns in zones Z1-Z4 connected in series; during water flushing, water enters from the chromatographic column in zone Z1 to flush the chlorogenic acid in the chromatographic columns in zones Z1-Z3 connected in series and connected. At this time, the chlorogenic acid phase is collected at the discharge port of the last chromatographic column in zone Z3; during water analysis, water enters from the chromatographic column in zone Z1, and the stevioside phase is collected at the bottom of the chromatographic column in zone Z1. Feeding is carried out simultaneously with water analysis. The liquid to be treated enters from the first chromatographic column in series in zone Z3, and the chlorogenic acid phase is collected at the bottom of the last chromatographic column in zone Z3. Then, the next cycle is switched by switching the feed valve and the discharge valve.

[0035] Unless otherwise specified, the raw materials in the following examples and comparative examples are all commercially available products, and the conditions in the following examples and comparative examples are all conventional conditions unless otherwise specified.

[0036] The calculation method of the yield of chlorogenic acid and steviol glycoside in the following examples and comparative examples is as follows:

[0037] Chlorogenic acid yield (%) = [(product mass × chlorogenic acid content in the product) / (extract mass × extract solid content × extract dry matter chlorogenic acid content)] × 100%.

[0038] Stevioside yield (%) = [(product mass × content of stevioside in the product) / (extract mass × solid content of the extract × content of stevioside in the dry matter of the extract)] × 100%.

[0039] Example 1

[0040] A method for efficiently preparing chlorogenic acid using stevia extract comprises the following steps:

[0041] (1) 100 kg of stevia leaves were crushed and mixed with a 30 v / v% ethanol solution (the mass ratio of stevia powder to ethanol solution was 1:10), extracted at 45° C. for 1 h, filtered, and the filter residue and ethanol solution were mixed and extracted again. The extraction was repeated 4 times, and the filtrates were combined to obtain 3870 kg of extract (solid content of the extract was 1.16 wt%, chlorogenic acid content in the dry matter of the extract was 2.1 wt%, and total stevioside content was 29.8 wt%);

[0042] (2) using a nanofiltration membrane with a molecular weight cutoff of 400 Da to concentrate the extract (the operating pressure during concentration is 2.0 MPa and the temperature is 45° C.), adding pure water (the volume ratio of the feed liquid to the pure water is 2:1) to the concentrated liquid and then performing secondary concentration to obtain a retentate (solid content is 30 wt%), and recovering the permeate from the two concentration processes to obtain an ethanol solution;

[0043] (3) adding a 10 wt % NaHCO solution to the collected retentate to adjust the pH of the solution to 6.0 to obtain a solution to be treated;

[0044] (4) The treated liquid was pumped into a simulated moving bed chromatography system for separation, wherein the diameter of the chromatography column in the simulated moving bed chromatography separation system was 32 cm, the height was 18.8 cm, eight columns were connected in series, the chromatography column was filled with sodium type resin (Lanxiao Technology S1850), and the average particle size of the resin was 280 μm; the separation conditions were: one cycle included four processes: circulating flushing, water flushing, water analysis and feeding, water analysis and feeding were carried out simultaneously, and the chlorogenic acid phase was collected during the water flushing and feeding process, and the stevioside phase was collected during the water analysis process; the circulating liquid flushing volume was 41v of the volume of the single column chromatography column / v%, the water flushing amount is 19v / v% of the volume of the single column chromatographic column, the water analysis amount is 27v / v% of the volume of the single column chromatographic column, the feed amount of the treated liquid is 9v / v% of the volume of the single column chromatographic column; Va (circulation flushing flow rate) is: 550mL / min, Vb (water flushing flow rate) is 550mL / min, Vc (water analysis flow rate) is 550mL / min, Vd (feed flow rate) is 183mL / min, the circulation flushing time is 11.2min, the water flushing time is 5.2min, the water analysis time (feeding time) is 7.4min, and then switch to the next cycle;

[0045] (5) The collected stevioside phase was subjected to adsorption treatment with a macroporous adsorption resin, followed by washing and impurity removal with an alkali solution and an acid solution, and finally analyzed with an ethanol solution. The analyzed solution was concentrated with a reverse osmosis membrane, and the concentrated solution was successively impurity-removed with an anion resin and a cationic resin. The effluent was concentrated and dried to obtain 13.6 kg of stevioside product, with a total stevioside content of 96.2 wt % and a yield of 97.8%;

[0046] (6) A 2 wt % HCl solution was added to the chlorogenic acid phase to adjust the pH to 3.5, and then the phase was concentrated using a nanofiltration membrane with a molecular weight cutoff of 600 Da at an operating pressure of 2.0 MPa and a temperature of 45° C. to obtain a primary concentrate; the primary concentrate was concentrated at a temperature of 70° C. and a vacuum degree of -0.08 MPa to a solution solid content of 45 wt % to obtain a secondary concentrate; the secondary concentrate was spray-dried (the air inlet temperature was 180° C. and the air outlet temperature was 85° C.) to obtain 3982 g of chlorogenic acid product with a chlorogenic acid content of 21.7 wt % and a chlorogenic acid yield of 91.7%.

[0047] Example 2

[0048] A method for efficiently preparing chlorogenic acid using stevia extract comprises the following steps:

[0049] (1) 100 kg of stevia leaves were crushed and mixed with a 10 v / v% ethanol solution (the mass ratio of stevia powder to ethanol solution was 1:20), extracted at 30° C. for 0.5 h, filtered, and the filter residue and ethanol solution were mixed and extracted again. The extraction was repeated twice, and the filtrates were combined to obtain 3850 kg of extract (solid content of the extract was 1.16 wt%, chlorogenic acid content in the dry matter of the extract was 2.1 wt%, and total stevioside content was 27.9 wt%);

[0050] (2) using a nanofiltration membrane with a molecular weight cutoff of 600 Da to concentrate the extract (the operating pressure during concentration is 1.5 MPa and the temperature is 30° C.), adding pure water (the volume ratio of the feed liquid to the pure water is 2:1) to the concentrated feed liquid and then performing secondary concentration to obtain a retentate (solid content is 20 wt%), and recovering the permeate from the two concentration processes to obtain an ethanol solution;

[0051] (3) adding a 5 wt % KOH solution to the collected retentate to adjust the pH of the solution to 5.0 to obtain a solution to be treated;

[0052] (4) The treated liquid was pumped into a simulated moving bed chromatography system for separation, wherein the diameter of the chromatography column in the simulated moving bed chromatography separation system was 32 cm, the height was 18.8 cm, eight columns were connected in series, and the chromatography column was filled with potassium type resin (Lanxiao Technology S1850), and the average particle size of the resin was 220 μm; the separation conditions were: one cycle included four processes: circulating flushing, water flushing, water analysis and feeding, the water analysis and feeding processes were carried out simultaneously, and the chlorogenic acid phase was collected during the water flushing and feeding processes, and the stevioside phase was collected during the water analysis process, the circulating liquid flushing volume was 42 v / v% of the volume of the single column chromatography column, and the water flushing volume was The volume of the single column chromatography column is 18v / v%, the water analysis volume is 30v / v% of the volume of the single column chromatography column, and the feed volume of the liquid to be treated is 10v / v% of the volume of the single column chromatography column; the conditions for simulated moving bed chromatography separation are: Va (circulation flushing flow rate) is: 600mL / min, Vb (water flushing flow rate) is 600mL / min, Vc (water analysis flow rate) is 600mL / min, Vd (feed flow rate) is 200mL / min, the circulation flushing time is 10.6min, the water flushing time is 4.5min, the water analysis time (feeding time) is 7.5min, and then switch to the next cycle;

[0053] (5) The collected stevioside phase was subjected to adsorption treatment with a macroporous adsorption resin, followed by washing and impurity removal with an alkali solution and an acid solution, and finally analyzed with an ethanol solution. The analyzed solution was concentrated with a reverse osmosis membrane, and the concentrated solution was successively impurity-removed with an anion resin and a cationic resin. The effluent was concentrated and dried to obtain 12.8 kg of stevioside product, with a total stevioside content of 95.5 wt % and a yield of 98.1%;

[0054] (6) A 1 wt% HCl solution was added to the chlorogenic acid phase to adjust the pH to 4.5, and then the phase was concentrated using a nanofiltration membrane with a molecular weight cutoff of 800 Da at an operating pressure of 3.0 MPa and a temperature of 30°C to obtain a primary concentrate; the primary concentrate was concentrated at a temperature of 60°C and a vacuum degree of -0.1 MPa to a solution solid content of 55 wt% to obtain a secondary concentrate; the secondary concentrate was spray-dried (the air inlet temperature was 170°C and the air outlet temperature was 75°C) to obtain 4143 g of chlorogenic acid product with a chlorogenic acid content of 20.4 wt% and a chlorogenic acid yield of 90.1%.

[0055] Example 3

[0056] A method for efficiently preparing chlorogenic acid using stevia extract comprises the following steps:

[0057] (1) 100 kg of stevia leaves were crushed and mixed with a 40 v / v% ethanol solution (the mass ratio of stevia powder to ethanol solution was 1:5), extracted at 60° C. for 2 h, filtered, and the filter residue and ethanol solution were mixed and extracted again. The extraction was repeated 6 times, and the filtrates were combined to obtain 2910 kg of extract (solid content of the extract was 1.53 wt%, chlorogenic acid content in the dry matter of the extract was 2.2 wt%, and total stevioside content was 30.4 wt%);

[0058] (2) using a nanofiltration membrane with a molecular weight cutoff of 200 Da to concentrate the extract (the operating pressure during concentration is 3.0 MPa and the temperature is 60° C.), adding pure water (the volume ratio of the feed liquid to the pure water is 2:1) to the concentrated feed liquid and then performing secondary concentration to obtain a retentate (solid content 35 wt%), and recovering the permeate from the two concentration processes to obtain an ethanol solution;

[0059] (3) adding a 40 wt % KHCO solution to the collected retentate to adjust the pH of the solution to 6.5 to obtain a solution to be treated;

[0060] (4) The liquid to be treated is pumped into a simulated moving bed chromatography system for separation, wherein the diameter of the chromatography column in the simulated moving bed chromatography separation system is 32 cm, the height is 18.8 cm, eight columns are connected in series, and the chromatography column is filled with potassium type resin (Lanxiao Technology S1850), and the average particle size of the resin is 320 μm; the separation conditions are: one cycle includes four processes: circulating flushing, water flushing, water analysis and feeding, the water analysis and feeding processes are carried out simultaneously, and the chlorogenic acid phase is collected during the water flushing and feeding processes, and the stevioside phase is collected during the water analysis process. The circulating liquid flushing volume is 40 v / v% of the volume of the single column chromatography column, the water flushing volume is 20 v / v% of the volume of the single column chromatography column, the water analysis volume is 25 v / v% of the volume of the single column chromatography column, and the feed volume of the liquid to be treated is 8 v / v% of the volume of the single column chromatography column. The conditions for simulated moving bed chromatography separation were: Va (circulation flushing flow rate) was 520 mL / min, Vb (water flushing flow rate) was 650 mL / min, Vc (water desorption flow rate) was 470 mL / min, Vd (feed flow rate) was 150 mL / min, the circulation flushing time was 11.6 min, the water flushing time was 4.6 min, the water desorption time (feeding time) was 8.0 min, and then switched to the next cycle;

[0061] (5) The collected stevioside phase was subjected to adsorption treatment with a macroporous adsorption resin, followed by washing and impurity removal with an alkali solution and an acid solution, and finally analyzed with an ethanol solution. The analyzed solution was concentrated with a reverse osmosis membrane, and the concentrated solution was successively impurity-removed with an anion resin and a cationic resin. The effluent was concentrated and dried to obtain 13.8 kg of stevioside product, with a total stevioside content of 96.1 wt % and a yield of 98.0%;

[0062] (6) A 3 wt % HCl solution was added to the chlorogenic acid phase to adjust the pH to 3.0, and then the phase was concentrated using a nanofiltration membrane with a molecular weight cutoff of 400 Da at an operating pressure of 1.5 MPa and a temperature of 60° C. to obtain a primary concentrate; the primary concentrate was concentrated at a temperature of 80° C. and a vacuum degree of -0.06 MPa to a solution solid content of 30 wt % to obtain a secondary concentrate; the secondary concentrate was spray dried (the air inlet temperature was 160° C. and the air outlet temperature was 70° C.) to obtain 3711 g of chlorogenic acid product with a chlorogenic acid content of 23.8 wt % and a chlorogenic acid yield of 90.2%.

[0063] Example 4

[0064] A method for efficiently preparing chlorogenic acid using stevia extract comprises the following steps:

[0065] (1) 100 kg of stevia leaves were crushed and mixed with a 20 v / v% ethanol solution (the mass ratio of stevia powder to ethanol solution was 1:8), extracted at 40° C. for 1 h, filtered, and the filter residue and ethanol solution were mixed and extracted again. The extraction was repeated 5 times, and the filtrates were combined to obtain 3830 kg of extract (solid content of the extract was 1.21 wt%, chlorogenic acid content in the dry matter of the extract was 2.0 wt%, and total stevioside content was 26.5 wt%);

[0066] (2) using a nanofiltration membrane with a molecular weight cutoff of 800 Da to concentrate the extract (the operating pressure during concentration is 2.7 MPa and the temperature is 40° C.), adding pure water (the volume ratio of the feed liquid to the pure water is 2:1) to the concentrated liquid and then performing secondary concentration to obtain a retentate (solid content 25 wt%), and recovering the permeate from the two concentration processes to obtain an ethanol solution;

[0067] (3) adding a 20 wt % Na2CO3 solution to the collected retentate to adjust the pH of the solution to 5.5 to obtain a solution to be treated;

[0068] (4) The liquid to be treated was pumped into a simulated moving bed chromatography system for separation, wherein the diameter of the chromatography column in the simulated moving bed chromatography separation system was 32 cm, the height was 18.8 cm, eight columns were connected in series, the chromatography column was filled with sodium type resin (Lanxiao Technology S1850), and the average particle size of the resin was 300 μm; the separation conditions were: one cycle included four processes: circulating flushing, water flushing, water analysis and feeding, the water analysis and feeding processes were carried out simultaneously, and the chlorogenic acid phase was collected during the water flushing and feeding processes, and the stevioside phase was collected during the water analysis process, the circulating liquid flushing volume was 41 v / v% of the volume of the single column chromatography column, the water flushing volume was 19 v / v% of the volume of the single column chromatography column, the water analysis volume was 28 v / v% of the volume of the single column chromatography column, and the feed volume of the liquid to be treated was 9 v / v% of the volume of the single column chromatography column. The conditions for simulated moving bed chromatography separation were: Va (circulation flushing flow rate) was 570 mL / min, Vb (water flushing flow rate) was 520 mL / min, Vc (water desorption flow rate) was 570 mL / min, Vd (feed flow rate) was 183 mL / min, the circulation flushing time was 10.8 min, the water flushing time was 5.5 min, the water desorption time (feeding time) was 7.4 min, and then switched to the next cycle;

[0069] (5) The collected stevioside phase was subjected to adsorption treatment with a macroporous adsorption resin, followed by washing and impurity removal with an alkali solution and an acid solution, and finally analyzed with an ethanol solution. The analyzed solution was concentrated with a reverse osmosis membrane, and the concentrated solution was successively impurity-removed with an anion resin and a cationic resin. The effluent was concentrated and dried to obtain 12.7 kg of stevioside product, with a total stevioside content of 95.3 wt % and a yield of 98.6%;

[0070] (6) A 1.5 wt% HCl solution was added to the chlorogenic acid phase to adjust the pH to 4.0, and then concentrated using a nanofiltration membrane with a molecular weight cutoff of 500 Da at an operating pressure of 1.7 MPa and a temperature of 40°C to obtain a primary concentrate; the primary concentrate was concentrated to a solution solid content of 35 wt% at a temperature of 75°C and a vacuum degree of -0.07 MPa to obtain a secondary concentrate; the secondary concentrate was spray-dried (the air inlet temperature was 190°C and the air outlet temperature was 95°C) to obtain 4195 g of chlorogenic acid product with a chlorogenic acid content of 20.1 wt% and a chlorogenic acid yield of 91.0%.

[0071] Example 5

[0072] A method for efficiently preparing chlorogenic acid using stevia extract comprises the following steps:

[0073] (1) 100 kg of stevia leaves were crushed and mixed with a 25 v / v% ethanol solution (the mass ratio of stevia powder to ethanol solution was 1:15), extracted at 55° C. for 1 h, filtered, and the filter residue and ethanol solution were mixed and extracted again. The extraction was repeated 3 times, and the filtrates were combined to obtain 4390 kg of extract (solid content of the extract was 1.07 wt%, chlorogenic acid content in the dry matter of the extract was 2.1 wt%, and total stevioside content was 27.4 wt%);

[0074] (2) using a nanofiltration membrane with a molecular weight cutoff of 400 Da to concentrate the extract (the operating pressure during concentration is 1.8 MPa and the temperature is 50° C.), adding pure water (the volume ratio of the feed liquid to the pure water is 2:1) to the concentrated feed liquid and then performing secondary concentration to obtain a retentate (solid content 32 wt%), and recovering the permeate from the two concentration processes to obtain an ethanol solution;

[0075] (3) adding a 10 wt % KOH solution to the collected retentate to adjust the pH of the solution to 6.3 to obtain a solution to be treated;

[0076] (4) The treated liquid was pumped into a simulated moving bed chromatography system for separation, wherein the diameter of the chromatographic column in the simulated moving bed chromatography separation system was 32 cm, the height was 18.8 cm, eight columns were connected in series, and the chromatographic column was filled with potassium-type resin (Lanxiao Technology S1850), and the average particle size of the resin was 260 μm; the separation conditions were: one cycle included four processes: circulating flushing, water flushing, water analysis and feeding, the water analysis and feeding processes were carried out simultaneously, and the chlorogenic acid phase was collected during the water flushing and feeding processes, and the stevioside phase was collected during the water analysis process, and the circulating liquid flushing volume was 41v of the volume of the single column chromatography column. / v%, the water flushing amount is 19v / v% of the volume of the single column chromatographic column, the water analysis amount is 26v / v% of the volume of the single column chromatographic column, and the feed amount of the treated liquid is 9v / v% of the volume of the single column chromatographic column; Va (circulation flushing flow rate) is: 530mL / min, Vb (water flushing flow rate) is 530mL / min, Vc (water analysis flow rate) is 530mL / min, Vd (feed flow rate) is 183mL / min, the circulation flushing time is 11.7min, the water flushing time is 5.4min, the water analysis time (feeding time) is 7.4min, and then switch to the next cycle;

[0077] (5) The collected stevioside phase was subjected to adsorption treatment with a macroporous adsorption resin, followed by washing and impurity removal with an alkali solution and an acid solution, and finally analyzed with an ethanol solution. The analyzed solution was concentrated with a reverse osmosis membrane, and the concentrated solution was successively impurity-removed with an anion resin and a cationic resin. The effluent was concentrated and dried to obtain 13.2 kg of stevioside product, with a total stevioside content of 95.8 wt % and a yield of 98.3%;

[0078] (6) A 2.5 wt% HCl solution was added to the chlorogenic acid phase to adjust the pH to 3.5, and then concentrated using a nanofiltration membrane with a molecular weight cutoff of 600 Da at an operating pressure of 2.8 MPa and a temperature of 50°C to obtain a primary concentrate; the primary concentrate was concentrated to a solid content of 50 wt% at a temperature of 65°C and a vacuum degree of -0.09 MPa to obtain a secondary concentrate; the secondary concentrate was spray-dried (the air inlet temperature was 175°C and the air outlet temperature was 86°C) to obtain 4175 g of chlorogenic acid product with a chlorogenic acid content of 21.3 wt% and a chlorogenic acid yield of 90.2%.

[0079] In order to better verify that the technical solution of the present invention has a more excellent effect, the following is further explained with reference to Example 1 and combined with multiple comparative examples.

[0080] Comparative Example 1

[0081] Compared with Example 1, the difference is that the solid content of the liquid to be treated is 15wt%, and the other conditions are the same as Example 1, and 3989g of chlorogenic acid product is obtained, wherein the chlorogenic acid content is 19.8wt%, and the chlorogenic acid yield is 83.8%.

[0082] Comparative Example 2

[0083] Compared with Example 1, the difference is that the solid content of the liquid to be treated is 45wt%, and the other conditions are the same as Example 1, and 3977g of chlorogenic acid product is obtained, wherein the chlorogenic acid content is 19.6wt%, and the chlorogenic acid yield is 82.7%.

[0084] Comparative Example 3

[0085] Compared with Example 1, the difference is that the pH of the liquid to be treated is 4.0, and the other conditions are the same as those in Example 1, and 3842 g of chlorogenic acid product is obtained, wherein the chlorogenic acid content is 15.2 wt %, and the chlorogenic acid yield is 61.9%.

[0086] Comparative Example 4

[0087] Compared with Example 1, the difference is that the pH of the liquid to be treated is 7.5, and the other conditions are the same as those in Example 1, and 3416 g of chlorogenic acid product is obtained, wherein the chlorogenic acid content is 8.2 wt %, and the chlorogenic acid yield is 29.7%.

[0088] Comparative Example 5

[0089] Compared with Example 1, the difference is that the pH of the chlorogenic acid phase is 2.0, and the other conditions are the same as Example 1, and 3925 g of chlorogenic acid product is obtained, wherein the chlorogenic acid content is 14.3 wt%, and the chlorogenic acid yield is 59.5%.

[0090] Comparative Example 6

[0091] Compared with Example 1, the difference is that the pH of the chlorogenic acid phase is 5.0, and the other conditions are the same as Example 1, and 3911 g of chlorogenic acid product is obtained, wherein the chlorogenic acid content is 18.7 wt%, and the chlorogenic acid yield is 77.6%.

[0092] The above results are analyzed as follows:

[0093] The present invention combines simulated moving bed chromatography separation technology with nanofiltration membrane concentration and impurity removal technology, and effectively controls conditions to separate the chlorogenic acid phase and the stevioside phase, thereby obtaining a chlorogenic acid product with a high recovery rate and simplifying the chlorogenic acid extraction steps.

[0094] During simulated moving bed chromatography separation, the solid content and pH of the liquid to be treated will affect the separation effect. The solid content in Comparative Example 1 is reduced, and the effective yield of chlorogenic acid is reduced. This is mainly because when the solid content is low, the amount of extract is large, and more mobile phase is used during separation, which results in high energy consumption. In addition, stevioside and chlorogenic acid are water-soluble, and low solid content will affect the separation effect. The solid content of Comparative Example 2 is relatively high, and the purity and yield of chlorogenic acid are also reduced. Therefore, it is necessary to reasonably control the solid content of the concentrate during specific operations.

[0095] The appropriate pH will effectively reduce the binding of chlorogenic acid to the resin in the simulated moving bed chromatography separation system, thereby improving the separation effect. In Comparative Example 3, the pH of the liquid to be treated was too low, and in Comparative Example 4, the pH of the liquid to be treated was too high, and the yield and purity of chlorogenic acid decreased to a certain extent. Because when the pH is low, chlorogenic acid will have a certain degree of binding with the resin in the simulated moving bed chromatography separation system, resulting in incomplete separation of chlorogenic acid and stevioside, and if the pH is too high, chlorogenic acid will undergo anthraquinone reaction, thereby destroying chlorogenic acid and reducing the yield and purity of chlorogenic acid.

[0096] In order to ensure the stability of the chlorogenic acid phase, it is necessary to adjust its pH. When the pH of the chlorogenic acid phase after adjustment in Comparative Example 5 is too low and the pH of the chlorogenic acid phase after adjustment in Comparative Example 6 is too high, the purity and yield of chlorogenic acid are affected, because when the pH is low, acidic substances are easily precipitated, affecting the next step of concentration; when the pH is high, chlorogenic acid is easily oxidized by oxygen in the air during the concentration process, affecting the yield and purity of the product. Therefore, it is necessary to reasonably control the pH of the chlorogenic acid phase.

[0097] 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 efficiently preparing chlorogenic acid using stevia extract, characterized in that: The following steps are involved: (1) After concentrating the stevia extract, adjusting the pH of the concentrate to 5.0-6.5 to obtain a solution to be treated; (2) pumping the liquid to be treated into a simulated moving bed chromatography system for separation to obtain a chlorogenic acid phase and a stevioside phase; (3) adjusting the pH of the chlorogenic acid phase to 3.0-4.5, then sequentially performing nanofiltration membrane concentration, thermal concentration, and finally spray drying to obtain the chlorogenic acid product.

2. The method for efficiently preparing chlorogenic acid using stevia extract according to claim 1, characterized in that: In step (1), the stevia extract is obtained by extracting stevia powder with an ethanol solution as an extraction solution; during the extraction, the concentration of the ethanol solution is 10-40 v / v%, the mass ratio of stevia powder to the ethanol solution is 1:(5-20); and / or the temperature during the extraction is 30-60°C, the extraction is repeated 2-6 times, the single extraction time is 0.5-2h, and filtering is performed after each extraction, and the filtrates of multiple extractions are combined to obtain the stevia extract.

3. The method for efficiently preparing chlorogenic acid using stevia extract according to claim 2, characterized in that: In step (1), a nanofiltration membrane is used to concentrate the stevia extract, the cut-off molecular weight of the nanofiltration membrane is 200-800Da, the operating pressure is 1.5-3.0MPa, and the temperature is 30-60°C; the solid content of the concentrated solution is 20-35wt%.

4. The method for efficiently preparing chlorogenic acid using stevia extract according to claim 3, characterized in that: In step (1), when nanofiltration membrane is used for concentration, pure water is added to the primary retentate after concentration, and re-concentration is performed, the secondary retentate is collected, and the primary permeate and the secondary permeate are combined to obtain an ethanol solution; the volume ratio of the primary retentate to pure water is (2-3):

1.

5. The method for efficiently preparing chlorogenic acid using stevia extract according to claim 1, characterized in that: In step (1), a sodium salt solution or a potassium salt solution is used to adjust the pH value of the concentrated solution; and / or the sodium salt is at least one of NaOH, NaHCO3, and Na2CO3; and / or the concentration of the sodium salt solution is 5-40wt%; and / or the potassium salt is at least one of KOH, KHCO3, and K2CO3; and / or the concentration of the potassium salt solution is 5-40wt%.

6. The method for efficiently preparing chlorogenic acid using stevia extract according to claim 1, characterized in that: In step (2), the chromatographic column of the simulated moving bed chromatographic separation system is filled with sodium type resin or potassium type resin; the average particle size of the sodium type resin or potassium type resin is 220-320 μm; and / or the diameter-to-height ratio of the single column chromatographic column is 2:1-1.

5.

7. The method for efficiently preparing chlorogenic acid using stevia extract according to claim 6, characterized in that: In step (2), the simulated moving bed separation system comprises eight chromatographic columns connected in series and connected end to end; A cyclic separation process includes cyclic flushing, water flushing, water analysis, and feeding process, wherein the water analysis and feeding are carried out simultaneously, and the chlorogenic acid phase is recovered in the water flushing process and the feeding process, and the stevioside phase is recovered in the water analysis process; And / or in one cycle separation process, the circulating liquid flushing amount is 40-42v / v% of the volume of the single column chromatographic column, the water flushing amount is 18-20v / v% of the volume of the single column chromatographic column, the water analysis amount is 25-30v / v% of the volume of the single column chromatographic column, and the feed amount of the liquid to be treated is 8-10v / v% of the volume of the single column chromatographic column.

8. The method for efficiently preparing chlorogenic acid using stevia extract according to claim 7, characterized in that: The conditions for simulated moving bed chromatography separation are: circulating flushing flow rate is 520-600mL / min, water flushing flow rate is 520-650mL / min, water decomposition flow rate is 470-600mL / min, feed flow rate is 125-240mL / min, circulating flushing time is 10-12.2min, water flushing time is 4.2-5.8min, water decomposition time is 6.3-9.7min, and then switch to the next cycle.

9. The method for efficiently preparing chlorogenic acid using stevia extract according to claim 1, characterized in that: In step (3), the pH adjusting agent used to adjust the chlorogenic acid phase is HCl solution, and the concentration of the HCl solution is 1-3 wt%.

10. The method for efficiently preparing chlorogenic acid using stevia extract according to claim 1, characterized in that: In step (3), when the chlorogenic acid phase is treated with a nanofiltration membrane, the molecular weight cutoff of the nanofiltration membrane is 400-800Da, the operating pressure is 1.5-3.0MPa, and the temperature is 30-60°C; the solid content of the retentate after concentration is 10-25wt%; and / or the temperature during hot concentration is 60-80° C., the vacuum degree is -0.06 to -0.1 MPa, and the solid content of the concentrated liquid after concentration is 30-55 wt %; And / or the air inlet temperature during spray drying is 160-190°C, and the air outlet temperature is 70-95°C.