Method for purifying 3 '-sialic acid lactose

Abstract

The present invention relates to the field of breast milk oligosaccharide purification, and discloses a 3 '-sialic acid lactose purification method, which comprises: carrying out inactivation treatment and ceramic membrane filtration on a fermentation broth to remove thalli and large particle impurities so as to obtain a supernatant; lactose impurities are degraded through lactase enzymolysis, pigments and anion impurities are removed by combining divalent metal salt precipitation and activated carbon decoloration, and a decoloration solution is prepared; removing cations and anions by using ion exchange resin to obtain a desalted solution; a nanofiltration membrane is used for concentrating the desalted liquid, and the concentration of a target object is further improved; 3 '-sialic acid lactose is efficiently purified through a simulated moving bed separation technology, the purity of the product is ensured, and finally the high-purity 3'-sialic acid lactose powder is prepared through evaporation concentration and spray drying. The process is optimized, the efficiency is high, the purity of the target product can reach 95% or above, the yield reaches 84%, the cost is low, the environmental protection property is high, and the method is suitable for industrial large-scale production.

Description

Technical Field

[0001] The invention relates to the technical field of breast milk oligosaccharide purification, in particular to a method for purifying 3'-sialyllactose. Background Art

[0002] Human milk oligosaccharides (HMOs) are the third most abundant component in human milk, second only to lactose and fat, and are composed of more than 150 different oligosaccharides. Studies have shown that HMOs play a vital role in the immune system, intestinal health, and nervous system development of newborns. Among them, sialylated human milk oligosaccharides (SHMOs), as an important acidic component of HMOs, contain sialic acid and exhibit unique biological functions:

[0003] Protecting the intestine: Studies have shown that SHMOs can effectively prevent necrotizing enterocolitis and neutralize the colonization or toxin release of various pathogens such as Helicobacter pylori, Escherichia coli, and Vibrio cholerae.

[0004] Promoting neonatal health: SHMOs maintain intestinal ecological balance by promoting the growth of beneficial intestinal bacteria (such as bifidobacteria); their structural characteristics can also act as "bait" molecules, competitively binding with pathogens, thereby reducing the risk of neonatal infection.

[0005] Among SHMOs, 3'-Sialyllactose (3'-SL) and 6'-Sialyllactose (6'-SL) are the two components with the highest content, especially 3'-SL, which plays an important role in neonatal development, including:

[0006] Stimulate the growth of beneficial intestinal bacteria: maintain the balance of intestinal flora and enhance intestinal immune function.

[0007] Providing raw materials for neural development: Sialic acid is an important component of gangliosides and sialic acid-binding glycoproteins. Sialic acid taken in through 3'-SL can promote the development and functional improvement of the neonatal nervous system.

[0008] At present, the industrial production of 3'-SL is mainly through microbial fermentation or enzymatic synthesis. However, the 3'-SL produced by these methods is mixed with lactose, protein, salt ions, small molecular impurities and other oligosaccharides, and further purification is required to obtain high-purity products.

[0009] Overview of existing technology:

[0010] In the purification technology of 3'-SL, some patents and literatures have proposed relevant methods:

[0011] Patent CN117778496A: This technology removes biomass from the fermentation broth by microfiltration and ultrafiltration, then uses ion exchange chromatography to remove anions and cations, and then uses activated carbon decolorization, nanofiltration and diafiltration technology to separate and concentrate the liquid, and finally evaporates and concentrates it and separates it again by chromatography to obtain 3'-SL with a purity of 93%. However, this process is complicated, requires multiple ion exchange operations, is time-consuming, and resin washing produces toxic waste liquid, polluting the environment.

[0012] Patent CN114014896A: Provides a method for separation and purification of multi-enzyme catalytic liquid, which is concentrated and dried after multi-stage membrane filtration combined with ion exchange resin adsorption desalination to obtain 3'-SL with a purity of >95% and a yield of >90%. Although this method can obtain high-purity products, its multiple membrane filtration and resin use costs are high, which is suitable for laboratory research and difficult to scale up to industrial scale.

[0013] Patent CN112203519A: Ultrafiltration combined with ion exchange chromatography, nanofiltration, electrodialysis and spray drying technology is used to obtain high-purity 3'-SL. However, the purity of the final product of this technology can only reach more than 80%, and the efficiency of the multi-step separation process is low, which is difficult to meet the needs of large-scale production.

[0014] Problems with existing technologies:

[0015] Although the above technologies provide different ideas for the purification of 3'-SL, the following problems still exist:

[0016] Insufficient purity: Some methods cannot increase the purity of 3'-SL to more than 95%, which is difficult to meet the requirements of food and pharmaceutical applications.

[0017] Low yield: The complex multi-step separation process increases the loss rate of the target product and reduces economic efficiency.

[0018] Complex process: requires multiple chromatography or membrane separation steps, long process flow, difficult operation and high energy consumption.

[0019] High cost: The frequent use of resin and multi-stage filtration increases the cost of materials and equipment, and also places higher requirements on waste liquid treatment in the production process.

[0020] Heavy environmental burden: Some methods will produce a large amount of waste liquid containing salt or organic solvents, which will pollute the environment and increase the cost of wastewater treatment.

[0021] Therefore, the present invention provides a method for purifying 3'-sialyllactose to solve the deficiencies of the prior art. Summary of the invention

[0022] In view of the problems of insufficient purity, low yield, complex process, high production cost and environmental pollution in the purification of 3'-sialyllactose (3'-SL) in the prior art, the present invention provides an efficient, economical and environmentally friendly method for purifying 3'-sialyllactose. The present invention aims to solve the above problems by simplifying the process flow, optimizing the separation technology and improving the production efficiency, and obtain 3'-sialyllactose with high purity and high yield.

[0023] To achieve the above object, the present invention is implemented by the following technical scheme: a method for purifying 3'-sialyllactose, comprising the following steps:

[0024] Bacteria removal treatment: After the fermentation liquid is inactivated, it is filtered through a ceramic membrane to obtain the supernatant;

[0025] Through inactivation treatment, active microorganisms in the fermentation broth are killed to prevent degradation or contamination of the target in subsequent steps;

[0026] Ceramic membrane filtration effectively intercepts large particle impurities, such as bacteria, proteins and other insoluble substances, laying the foundation for subsequent fine separation.

[0027] Enzymatic decolorization: adding lactase to the supernatant for enzymatic hydrolysis, then adding a divalent metal salt for precipitation treatment, and further adding activated carbon for decolorization treatment to obtain a decolorized solution;

[0028] Ion exchange resin treatment: the decolorized liquid is sequentially treated with a strong acid cation exchange resin and a weak base anion exchange resin to remove impurities and obtain a desalted liquid;

[0029] Nanofiltration concentration: using a nanofiltration membrane to concentrate the desalted liquid to obtain a concentrated liquid;

[0030] Simulated moving bed separation: separating the concentrate by a simulated moving bed system, collecting 3'-sialyllactose from the target product zone of the simulated moving bed, and collecting impurities from the impurity zone;

[0031] Evaporation and concentration: Evaporating and concentrating the separated target product liquid to obtain a concentrated liquid with a sugar content greater than 50%;

[0032] Spray drying: The concentrated solution is spray dried to obtain 3'-sialyllactose product.

[0033] Preferably, the filtration pore size of the ceramic membrane is 50 nm to 500 nm.

[0034] The optimal design of the filtration pore size range (50nm to 500nm) ensures the complete retention of the target product while reducing operating energy consumption and improving filtration efficiency.

[0035] Preferably, the enzymatic decolorization step comprises:

[0036] Adding lactase to the supernatant, the amount of lactase added is 1% to 3% of the volume of the supernatant, the enzymolysis temperature is 30° C. to 50° C., and the enzymolysis time is 20 minutes to 60 minutes;

[0037] Adding a divalent metal salt for precipitation treatment, wherein the divalent metal salt is calcium chloride or magnesium chloride, and the amount added is 1% to 2% of the volume of the supernatant;

[0038] Activated carbon is added for decolorization, the amount of activated carbon added is 1% to 3% of the volume of the supernatant, the decolorization temperature is 35° C. to 50° C., and the decolorization time is 20 minutes to 60 minutes.

[0039] Lactase can specifically degrade impurities such as lactose and reduce the content of macromolecular interferences in the solution, thereby reducing the burden of subsequent separation steps.

[0040] Divalent metal salts (such as calcium chloride) can form insoluble precipitates with anions (such as phosphates and sulfates) in the solution, effectively removing inorganic impurities in the solution.

[0041] Activated carbon removes pigments, small organic molecules and other trace impurities through physical adsorption, improving the appearance and purity of the target product.

[0042] This step combines multiple treatment methods to ensure the high purity of the decolorizing solution and provide a clean base solution for subsequent separation.

[0043] Preferably, the ion exchange resin comprises:

[0044] Strong acid cation exchange resin, pretreated by acid-base-acid method, with loading rate of 1 to 3 bed volumes per hour;

[0045] Weakly basic anion exchange resin, pretreated with 8% sodium chloride solution, with a loading rate of 2 to 4 bed volumes per hour;

[0046] During the resin adsorption process, the pH value of the solution was adjusted to 4 to 7.

[0047] Ion exchange resins remove cationic and anionic impurities in the solution, such as calcium ions, magnesium ions and sulfate, through electrostatic adsorption, significantly improving the purity of the solution.

[0048] Acid-base-acid and sodium chloride pretreatment ensures the adsorption efficiency and separation effect of the resin and prolongs the service life of the resin.

[0049] Adjusting the pH value to 4 to 7 can optimize the adsorption performance of the resin, while avoiding the loss of the target product and improving the separation yield.

[0050] This step significantly reduces the ionic impurities in the solution, laying the foundation for further separation of the target compound.

[0051] Preferably, the molecular weight cutoff of the nanofiltration membrane is 300D to 1000D, the nanofiltration operating pressure is 2 to 6 bar, and the operating temperature is 5°C to 30°C.

[0052] Nanofiltration membranes use the principle of semi-permeable membrane separation to further remove low molecular weight impurities and concentrate the target product by selectively intercepting a specific molecular weight range.

[0053] The preferred molecular weight cut-off range (300D to 1000D) ensures efficient recovery of the target product, while significantly increasing the concentration of the target product and reducing the energy consumption required for subsequent separation and drying.

[0054] Low temperature operation (5°C to 30°C) avoids degradation of the target product at high temperature and ensures product quality and purity.

[0055] Preferably, the simulated moving bed system comprises six resin columns with a column diameter of 8 cm to 12 cm and a column height of 1 m to 1.2 m; the operation cycle time of the simulated moving bed is 300 seconds to 600 seconds, and the column temperature is 20°C to 60°C.

[0056] The simulated moving bed technology can efficiently separate the target component (3'-sialyllactose) and impurities through the countercurrent continuous separation principle, significantly improving the separation efficiency.

[0057] The traditional multi-zone design (such as target product zone and impurity zone) ensures the precise separation of different components and realizes the automation and continuity of operation.

[0058] The optimal cycle time and column temperature range further optimize the separation, ensuring a purity of 3'-sialyllactose of more than 95% while reducing energy consumption and cost.

[0059] Compared with traditional multi-step ion exchange chromatography separation, simulated moving bed operation is more efficient and environmentally friendly, avoiding frequent cleaning of large amounts of resin and the generation of waste liquid.

[0060] Preferably, a double-effect evaporator or a scraper evaporator is used in the evaporation and concentration step, the evaporation temperature is 40° C. to 70° C., and the sugar content of the concentrated liquid after evaporation is greater than 50%.

[0061] The double-effect evaporator utilizes multi-effect steam heat recovery technology to significantly reduce energy consumption; the scraped-plane evaporator avoids thermal degradation of the target product through efficient heat exchange.

[0062] The evaporation temperature is controlled between 40°C and 70°C to ensure rapid concentration while maintaining the chemical stability of the target product.

[0063] The concentrate with high sugar content not only improves the subsequent drying efficiency, but also facilitates transportation and storage.

[0064] Preferably, the inlet air temperature of the spray drying is 110°C to 150°C, the outlet air temperature is 75°C to 95°C, and the feed flow rate is 15 mL / min to 30 mL / min.

[0065] Spray drying produces high-purity powdered 3'-sialyllactose by rapidly evaporating the water in the liquid.

[0066] The optimal drying temperature and feed flow rate ensure rapid drying of the product while avoiding degradation or property changes of the target product due to high temperature.

[0067] The powder product prepared in this step has high stability and is easy to store and subsequently process.

[0068] Preferably, during the simulated moving bed separation process, the concentration of 3'-sialyllactose in the collected solution from the target product zone is 150 g / L to 400 g / L.

[0069] The present invention provides a method for purifying 3'-sialyllactose, which has the following beneficial effects:

[0070] 1. The present invention adopts a technical solution of ceramic membrane filtration combined with ion exchange resin treatment and simulated moving bed separation, and optimizes the separation and purification process to ensure that the purity of 3'-sialyllactose (3'-SL) reaches more than 95%. Compared with the prior art, such as patent CN117778496A, which relies on multiple ion exchange chromatography to achieve a purity of 93% and takes a long time, the present invention uses efficient simulated moving bed separation technology, which not only simplifies the process flow, but also significantly improves the separation efficiency, solving the problem of insufficient product purity in the prior art.

[0071] 2. The present invention optimizes the conditions of enzymatic decolorization, nanofiltration concentration and simulated moving bed separation, reasonably reduces product loss, and increases the yield of 3'-sialyllactose to more than 80%. Compared with the prior art, such as patent CN112203519A, which causes a large loss of target product due to complex ultrafiltration and multi-step electrodialysis, the process optimization of the present invention achieves higher resource utilization, solves the problem of low product yield due to multi-step operation in the prior art, and meets the yield requirements of industrial production.

[0072] 3. The present invention adopts continuous and automated simulated moving bed separation technology, which effectively reduces multiple chromatographic operations and multi-stage membrane filtration steps in the traditional purification process, significantly simplifying the production process. At the same time, by reducing the dependence on resins and solvents and optimizing energy consumption links, the consumption of materials and energy is reduced, and the production cost is significantly reduced. Compared with the prior art, such as patent CN114014896A, which requires multiple membrane filtration and resin use, resulting in high costs, the present invention solves the problems of high cost, complex process and high energy consumption in the prior art by introducing simulated moving bed and efficient evaporation concentration technology.

[0073] 4. The present invention adopts an environmentally friendly process, using only a small amount of metal salts (such as calcium chloride or magnesium chloride) and activated carbon in the purification process, without the need for organic solvents, and reducing environmental pollution and wastewater treatment costs by optimizing separation and waste liquid discharge treatment technology. The present invention has significant industrial adaptability by simulating the continuous and efficient operation of moving bed separation, combined with double-effect evaporator and spray drying equipment. Compared with the prior art, such as patent CN117778496A, which has serious toxic waste liquid discharge due to resin cleaning or patent CN114014896A, which is difficult to achieve large-scale production, the present invention meets the needs of large-scale industrial production on the basis of green environmental protection. BRIEF DESCRIPTION OF THE DRAWINGS

[0074] Figure 1 This is a graph showing the purity of 3'-sialyllactose obtained after spray drying in Example 1 by high performance liquid chromatography;

[0075] Figure 2 This is a graph showing the purity of 3'-sialyllactose obtained after spray drying in Example 2 by high performance liquid chromatography;

[0076] Figure 3 This is a graph showing the purity of 3'-sialyllactose obtained after spray drying in Example 3 by high performance liquid chromatography;

[0077] Figure 4 This is a graph showing the purity of 3'-sialyllactose obtained by spray drying in Example 4 by high performance liquid chromatography;

[0078] Figure 5 The figure is a flow chart of the separation and purification method of multi-enzyme catalytic liquid. DETAILED DESCRIPTION

[0079] The technical solution of the present invention will be described clearly and completely below in conjunction with the accompanying drawings of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0080] Please see attached Figure 1 -Attached Figure 5 :

[0081] Embodiment 1:

[0082] Step S1: Bacteria removal treatment

[0083] The fermentation liquid was inactivated (heated to 85°C for 15 minutes), and the inactivated fermentation liquid was filtered through a ceramic membrane with a pore size of 50nm to remove bacteria and large particles. The filtered liquid was further centrifuged at a speed of 8000rpm for 15 minutes to obtain a clear supernatant.

[0084] Step S2: Enzymatic decolorization

[0085] Add 2% lactase (by volume of solution) to the above supernatant and perform enzymolysis at a constant temperature of 40°C for 60 minutes to decompose lactose and small molecular impurities. Subsequently, add 1% calcium chloride to the enzymolysis solution, stir evenly and let stand for 10 minutes to precipitate anionic impurities in the liquid with calcium chloride; then add 2% activated carbon and stir and mix at 40°C for 60 minutes to remove pigments and other organic impurities. Finally, heat the mixture to 65°C for 10 minutes to inactivate lactase, and filter with a plate and frame filter to obtain a clear decolorized solution.

[0086] Step S3: Ion exchange resin treatment

[0087] The decolorized solution was processed through the following resins in sequence:

[0088] Strong acid cation exchange resin: pretreatment is performed using the acid-base-acid method. The loading rate is controlled to be 2 times the bed volume per hour, and the loading solution is 4 times the bed volume to remove cationic impurities;

[0089] Weakly basic anion exchange resin: Use 8% sodium chloride solution for pretreatment. The loading speed is controlled to 3 times the bed volume per hour, and the loading solution is 3.5 times the bed volume to remove anionic impurities;

[0090] During the whole process, the pH value of the solution was adjusted to 7 to ensure the best separation effect. After treatment, desalted liquid was obtained.

[0091] Step S4: Nanofiltration Concentration

[0092] The desalted liquid was concentrated by a nanofiltration device, a nanofiltration membrane with a molecular weight cutoff of 1000D was selected, an operating pressure of 5 bar, an operating temperature of 20°C, and a concentration time of 2 hours, and finally a sugar-containing concentrated liquid was obtained.

[0093] Step S5: Simulated Moving Bed Separation

[0094] The concentrate is separated and purified by a simulated moving bed (SMB) system. The system consists of six resin columns with a column diameter of 10 cm and a column height of 1.1 m. The resin columns are divided into four partitions:

[0095] Z1 zone (1 column): impurity collection zone;

[0096] Z2 zone (2 columns): auxiliary separation zone;

[0097] Z3 zone (2 columns): target product collection zone;

[0098] Zone Z4 (1 column): solid phase regeneration zone.

[0099] The system operation cycle was 500 seconds, and the column temperature was controlled at 25° C. The target product 3'-sialyllactose solution was collected from the Z3 zone, and the impurity solution was collected from the Z1 zone.

[0100] Step S6: Evaporation and concentration

[0101] The target product liquid obtained by simulated moving bed separation is concentrated by a double-effect evaporator at an evaporation temperature of 60° C., and the sugar content of the concentrated liquid is finally greater than 50%.

[0102] Step S7: Spray Drying

[0103] The concentrated liquid was sent to a spray drying device under the following drying conditions: inlet air temperature of 140°C, outlet air temperature of 90°C, and feed flow rate of 20 mL / min. After drying, 3'-sialyllactose powder product was obtained.

[0104] result:

[0105] 3'-sialyllactose product purity: 86.3%;

[0106] Yield: 67.7%.

[0107] Embodiment 2:

[0108] The process of Example 2 is basically the same as that of Example 1, and the following operating conditions are mainly adjusted:

[0109] Enzymatic decolorization: the amount of lactase added was 2%, the enzymatic hydrolysis temperature was 40°C, and the enzymatic hydrolysis time was 60 minutes; 1% calcium chloride was added for precipitation, 2% activated carbon was added and stirred at 40°C for 60 minutes, and then the temperature was raised to 65°C to inactivate lactase.

[0110] Ion exchange resin treatment: The loading rate of the strongly acidic cation exchange resin was 2 times the bed volume per hour, and the loading rate of the weakly basic anion exchange resin was 3 times the bed volume per hour. The pH value was adjusted to 4.

[0111] Simulated moving bed separation: The simulated moving bed cycle time was adjusted to 400 s and the column temperature was controlled at 25 °C.

[0112] result:

[0113] 3'-sialyllactose product purity: 88.4%;

[0114] Yield: 82.5%.

[0115] Embodiment 3:

[0116] The process of Example 3 is basically the same as that of Example 1, and the following conditions are mainly optimized:

[0117] Enzymatic decolorization: The amount of lactase added, temperature and time were the same as those in Example 1; the calcium chloride precipitation and activated carbon decolorization conditions were kept the same.

[0118] Ion exchange resin treatment: The loading rates of the cation exchange resin and anion exchange resin were controlled at 2 and 3 times the bed volume per hour, respectively, and the pH value of the solution was adjusted to 4.

[0119] Simulated moving bed separation: The cycle time of the simulated moving bed was adjusted to 400 s and the column temperature was adjusted to 45 °C.

[0120] result:

[0121] 3'-sialyllactose product purity: 93.1%;

[0122] Yield: 84.0%.

[0123] Embodiment 4:

[0124] The process of Example 4 is basically the same as that of Example 1, and the following conditions are further optimized:

[0125] Simulated moving bed separation: The operation cycle time was adjusted to 400 s and the column temperature was further increased to 55 °C.

[0126] Spray drying: inlet air temperature was 130°C, outlet air temperature was 95°C, and feed flow rate was 20 mL / min.

[0127] result:

[0128] 3'-sialyllactose product purity: 95.7%;

[0129] Yield: 84.3%.

[0130] Summary of test methods and results

[0131] Purity test:

[0132] Mobile phase: 1mmol / L sulfuric acid aqueous solution;

[0133] Chromatographic column: Rezex RNM-Carbohydrate Na+(8%)300×7.8mm;

[0134] Detection conditions: column temperature 82°C, flow rate 0.6 mL / min, injection volume 10 μL;

[0135] Purity calculation formula:

[0136]

[0137] Yield calculation:

[0138]

[0139] Summary table:

[0140] Example purity(%) Yield (%) Example 1 86.3 67.7 Example 2 88.4 82.5 Example 3 93.1 84 Example 4 95.7 84.3

[0141] Through the technical verification of the examples, the present invention successfully achieves the efficient purification of 3'-sialyllactose, significantly improves the purity and yield of the target product, simplifies the process flow, reduces costs and enhances environmental protection. The above examples fully demonstrate the operability, applicability and industrial promotion potential of the present invention, and have significant technical advantages and economic value.

[0142] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A method for purifying 3'-sialyllactose, characterized in that: The following steps are involved: Bacteria removal treatment: After the fermentation liquid is inactivated, it is filtered through a ceramic membrane to obtain the supernatant; Enzymatic decolorization: adding lactase to the supernatant for enzymatic hydrolysis, then adding a divalent metal salt for precipitation treatment, and further adding activated carbon for decolorization treatment to obtain a decolorized solution; Ion exchange resin treatment: the decolorized liquid is sequentially treated with a strong acid cation exchange resin and a weak base anion exchange resin to remove impurities and obtain a desalted liquid; Nanofiltration concentration: using a nanofiltration membrane to concentrate the desalted liquid to obtain a concentrated liquid; Simulated moving bed separation: separating the concentrate by a simulated moving bed system, collecting 3'-sialyllactose from the target product zone of the simulated moving bed, and collecting impurities from the impurity zone; Evaporation and concentration: Evaporating and concentrating the separated target product liquid to obtain a concentrated liquid with a sugar content greater than 50%; Spray drying: The concentrated solution is spray dried to obtain 3'-sialyllactose product.

2. A method for purifying 3'-sialyllactose according to claim 1, characterized in that: The filtration pore size of the ceramic membrane is 50nm to 500nm.

3. A method for purifying 3'-sialyllactose according to claim 1, characterized in that: The enzymatic decolorization step comprises: Adding lactase to the supernatant, the amount of lactase added is 1% to 3% of the volume of the supernatant, the enzymolysis temperature is 30° C. to 50° C., and the enzymolysis time is 20 minutes to 60 minutes; Adding a divalent metal salt for precipitation treatment, wherein the divalent metal salt is calcium chloride or magnesium chloride, and the amount added is 1% to 2% of the volume of the supernatant; Activated carbon is added for decolorization, the amount of activated carbon added is 1% to 3% of the volume of the supernatant, the decolorization temperature is 35° C. to 50° C., and the decolorization time is 20 minutes to 60 minutes.

4. A method for purifying 3'-sialyllactose according to claim 1, characterized in that: The ion exchange resin comprises: Strong acid cation exchange resin, pretreated by acid-base-acid method, with loading rate of 1 to 3 bed volumes per hour; Weakly basic anion exchange resin, pretreated with 8% sodium chloride solution, with a loading rate of 2 to 4 bed volumes per hour; During the resin adsorption process, the pH value of the solution was adjusted to 4 to 7.

5. A method for purifying 3'-sialyllactose according to claim 1, characterized in that: The molecular weight cutoff of the nanofiltration membrane is 300D to 1000D, the nanofiltration operating pressure is 2 to 6 bar, and the operating temperature is 5°C to 30°C.

6. A method for purifying 3'-sialyllactose according to claim 1, characterized in that: The simulated moving bed system includes six resin columns with a column diameter of 8 cm to 12 cm and a column height of 1 m to 1.2 m; the operation cycle time of the simulated moving bed is 300 seconds to 600 seconds, and the column temperature is 20° C. to 60° C.

7. A method for purifying 3'-sialyllactose according to claim 1, characterized in that: In the evaporation and concentration step, a double-effect evaporator or a scraper evaporator is used, the evaporation temperature is 40° C. to 70° C., and the sugar content of the concentrated liquid after evaporation is greater than 50%.

8. A method for purifying 3'-sialyllactose according to claim 1, characterized in that: The inlet air temperature of the spray drying is 110° C. to 150° C., the outlet air temperature is 75° C. to 95° C., and the feed flow rate is 15 mL / min to 30 mL / min.

9. A method for purifying 3'-sialyllactose according to claim 1, characterized in that: During the simulated moving bed separation process, the concentration of 3'-sialyllactose collected from the target product zone is 150 g / L to 400 g / L.

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