Method for preparing gamma-cyclodextrin through precipitation technology and separation enzyme method

Abstract

The invention discloses a method for preparing gamma-cyclodextrin by a precipitation technology and a separation enzyme method, which comprises the following steps: by taking gamma-cyclodextrin mother liquor prepared by a solvent method and an enzyme method as a sample solution, firstly dissociating a compound formed by gamma-cyclodextrin and a reaction aid under a high-temperature condition, and then separating the gamma-cyclodextrin by a precipitation separation technology to obtain the gamma-cyclodextrin. An inorganic salt precipitator is added to effectively separate out a reactant, so that the purification of a target product is realized, and an efficient and simple gamma-cyclodextrin separation and purification method is established. By adopting the method disclosed by the invention, the total conversion rate of the gamma-cyclodextrin can reach about 53.89%, the recovery rate of the separated gamma-cyclodextrin can reach 82.76%-90.84%, and the purity of the separated gamma-cyclodextrin is 92.56%-95.63%. The residual quantity of the reaction auxiliary agent is 0.02%.

Description

Technical Field

[0001] The invention belongs to the technical field of chemical separation and purification, and specifically relates to a method for preparing gamma-cyclodextrin by a precipitation technology separation enzyme method. Background Art

[0002] Cyclodextrin is a type of cyclic oligomer composed of D-pyranose glucose units connected by α-1,4-glycosidic bonds. Its spatial structure is a hollow cylindrical structure, so it has both a hydrophilic surface and a hydrophobic cavity structure. It is a kind of embedding material with broad application prospects and has been used in the fields of medicine, food, cosmetics, materials, etc. Cyclodextrin can be classified according to the number of glucose units that make up cyclodextrin. The common cyclodextrins composed of 6, 7, and 8 glucose units are named α-cyclodextrin, β-cyclodextrin, and γ-cyclodextrin, respectively.

[0003] Compared with α- and β-cyclodextrin, γ-cyclodextrin has a larger inner cavity and can contain larger or more complex molecules, so it has broad application prospects in the fields of medicine, food, and cosmetics. Since γ-cyclodextrin has good water solubility (25g / 100mL water at 25°C) and biocompatibility, it shows higher dissolution efficiency when forming complexes with guest molecules with poor water solubility, and has broader application prospects in the fields of food and medicine. However, the preparation and separation and purification of γ-cyclodextrin are very difficult, mainly because it is difficult to separate it from the reaction aid.

[0004] At present, the production of γ-cyclodextrin is mainly synthesized by catalysis of γ-cyclodextrin glucosyltransferase using starch as a substrate. However, in the production process, organic reagents such as large-ring ketone compounds are usually added to increase the yield, and the commonly used reaction aid is cyclododecanone, as described in CN201310036791 and CN102827900B patents. In these patents, the removal of the reaction aid mainly adopts steam distillation, but the method has the problems of high energy consumption and long time consumption, and it is difficult to meet the needs of industrial production. In addition, CN109400760A reports a method for purifying γ-cyclodextrin using cyclodextrin hydrolase, but because the method has strict requirements on the steps such as enzyme screening and reaction conditions, it is easy to cause enzyme inactivation, and is not conducive to industrial amplification production. Therefore, it is urgent to develop an efficient and rapid separation and purification method to reduce costs and improve production efficiency. Summary of the invention

[0005] The purpose of this section is to summarize some aspects of embodiments of the present invention and briefly introduce some preferred embodiments. Some simplifications or omissions may be made in this section and the specification abstract and the invention title of this application to avoid blurring the purpose of this section, the specification abstract and the invention title, and such simplifications or omissions cannot be used to limit the scope of the present invention.

[0006] In view of the above problems and / or the problems existing in the prior art, the present invention is proposed.

[0007] Therefore, the purpose of the present invention is to overcome the deficiencies in the prior art and provide a method for preparing γ-cyclodextrin by separation and enzymatic method using precipitation technology.

[0008] In order to solve the above technical problems, the present invention provides the following technical solution: a method for preparing γ-cyclodextrin by separation and enzymatic method using precipitation technology, characterized in that: it comprises:

[0009] The complex formed by gamma-cyclodextrin and a reaction aid is diluted and dissociated at high temperature, a precipitant is added, stirred and filtered to obtain a solution, an ion exchange resin is used to desalt the solution, and the solution is concentrated and dried to obtain high-purity gamma-cyclodextrin.

[0010] As a preferred embodiment of the preparation method of the present invention, the precipitant is a soluble potassium salt solution, including one or more of potassium phosphate, potassium hydroxide, potassium acetate, potassium chloride solution, and potassium dihydrogen phosphate.

[0011] As a preferred embodiment of the preparation method of the present invention, the reaction aid is a phenyl-substituted borate or a phenyl-substituted borate derivative, including one or more of 2-fluorophenylboric acid, methylphenylboric acid, 4-nitrophenylboric acid, and sodium tetraphenylborate.

[0012] As a preferred embodiment of the preparation method of the present invention, the complex formed by γ-cyclodextrin and the reaction aid is diluted and dissociated at high temperature, wherein the dilution multiple is 2 to 10 times, the temperature is 60 to 95° C., and the time is 1 to 2 hours.

[0013] As a preferred solution of the preparation method of the present invention, the concentration of the precipitant is 20-50%.

[0014] As a preferred embodiment of the preparation method of the present invention, the precipitant is added and stirred, wherein the stirring temperature is 70-95° C., the stirring rate is 150-200 rpm, and the time is 1-60 min.

[0015] As a preferred embodiment of the preparation method of the present invention, the ion exchange resin includes an anion exchange resin and a cation exchange resin, wherein the anion exchange resin includes a macroporous weak base styrene anion exchange resin, and the cation exchange resin includes a macroporous strong acid styrene cation exchange resin.

[0016] As a preferred embodiment of the preparation method of the present invention, the desalting treatment conditions are as follows: the conductivity of the material at the outlet of the ion exchange resin column is less than 50 μs / cm, the feeding is stopped and the ion exchange resin is regenerated; the temperature of the filtrate is 10 to 50°C, the pH is 4.0 to 8.0, and the injection flow rate is 1 to 2 BV / h.

[0017] Another object of the present invention is to overcome the deficiencies in the prior art and provide a method for preparing γ-cyclodextrin by using a precipitation technique to separate and enzymatically prepare γ-cyclodextrin.

[0018] The recovery rate of the γ-cyclodextrin is 82.76% to 90.84%, and the purity is 92.56% to 95.63%

[0019] Beneficial effects of the present invention:

[0020] (1) The present invention uses the γ-cyclodextrin mother liquor prepared by the solvent method and the enzyme method as the sample solution, and separates and purifies the target product by the salt precipitation method, thereby establishing a new, efficient and simple method for separating and purifying γ-cyclodextrin. By dissociating the complex at high temperature and separating by inorganic salt precipitation, the entire process is simple to operate, eliminating the cumbersome purification steps, and greatly reducing the equipment requirements and operating difficulty. At the same time, the method of the present invention is suitable for large-scale production, which helps to improve the operability and stability of industrial applications. The method ultimately achieved a γ-cyclodextrin recovery rate of 90.84%, and the purity of the resulting product was as high as 95.63%.

[0021] (2) The present invention uses ion exchange resin to desalt the separated stock solution, and the final conductivity is less than 50 μs / cm, which significantly reduces the impurity content in the product and further improves the quality of γ-cyclodextrin. While ensuring the high purity of the product, the desalination process simplifies the subsequent purification steps and effectively reduces the production cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for describing the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative labor. Among them:

[0023] Figure 1 The HPLC spectrum of the raw liquid to be treated obtained when 15% (w / w) cassava starch is used as a substrate of the present invention.

[0024] Figure 2 The HPLC spectrum of the product after separation by the precipitation method of the present invention.

[0025] Figure 3This is the effect of temperature on precipitation separation in the present invention.

[0026] Figure 4 This is the effect of the amount of potassium chloride added on the precipitation separation of the present invention. DETAILED DESCRIPTION

[0027] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the specific implementation methods of the present invention are described in detail below in conjunction with the embodiments of the specification.

[0028] In the following description, many specific details are set forth to facilitate a full understanding of the present invention, but the present invention may also be implemented in other ways different from those described herein, and those skilled in the art may make similar generalizations without violating the connotation of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed below.

[0029] Secondly, the term "one embodiment" or "embodiment" as used herein refers to a specific feature, structure, or characteristic that may be included in at least one implementation of the present invention. The term "in one embodiment" that appears in different places in this specification does not necessarily refer to the same embodiment, nor does it refer to a separate or selective embodiment that is mutually exclusive with other embodiments.

[0030] Unless otherwise specified, all raw materials used in the examples of the present invention are commercially available, as shown in Table 1 for details.

[0031] Table 1

[0032]

[0033] Among them, the γ-cyclodextrin glucosyltransferase is derived from a genetically engineered strain of Bacillus subtilis containing the gene sequence of the enzyme. (Among them, the publicly reported literature on γ-cyclodextrin glucosyltransferase: Wang Lei. Recombinant expression and application of Bacillus clarkii 7364 γ-cyclodextrin glucosyltransferase [D]. Jiangnan University, 2013.; the literature on the construction of genetically engineered strains of Bacillus subtilis doi number: 10.1021 / acs.jafc.2c08320)

[0034] The anion exchange resin used in the examples is specifically the D354 anion exchange resin from Hangzhou Zhengguang Resin Co., Ltd.; the cation exchange resin is specifically the D001 cation exchange resin from Hangzhou Zhengguang Resin Co., Ltd.; and sodium tetraphenylborate is purchased from Shanghai Titan Technology Co., Ltd.

[0035] The detection method of cyclodextrin in the examples and comparative examples of the present invention adopts high performance liquid chromatography: the reaction solution is boiled in water for 30 minutes to kill the enzyme, diluted 10 times with the mobile phase, centrifuged (10,000×g, 10 minutes) after standing for 30 minutes, and the supernatant is filtered through a 0.22μm organic filter membrane and then analyzed by high performance liquid chromatography (HPLC). The HPLC conditions are: Waters 1525 high performance liquid chromatograph system (with differential refractive index detector), chromatographic column ChemCore NH2 (4.6×250mm), column temperature of 40°C, mobile phase of 70% (v / v) acetonitrile aqueous solution, flow rate of 1mL / min.

[0036] Example 1

[0037] (1) A 15% (w / w) dry cassava starch solution was used as the substrate and the slurry was first slurried at 55°C for 10 min. Then, γ-cyclodextrin glucosyltransferase was added at a rate of 3U enzyme solution / g starch, and the mixture was heated to 90°C to gelatinize and liquefy the starch. Next, the enzyme was inactivated at 90°C for 30 min, and then the temperature was lowered to 55°C. At 55°C, γ-cyclodextrin glucosyltransferase was added to the reaction system again at a rate of 5U enzyme solution / g starch, and a reaction aid sodium tetraphenylborate was added at a rate of 2% of the total mass of the system to carry out a cyclization reaction. After 12 h of reaction, the enzyme was inactivated in a boiling water bath for 30 min to obtain the stock solution to be treated.

[0038] (2) The raw liquid to be treated was diluted 5 times with pure water to obtain a liquid with a material concentration of 1.5%, and the temperature was increased to 90° C. at a heating rate of 5° C. / min and kept at this temperature for 60 min.

[0039] (3) After the insulation is completed, maintain 90°C, gradually add 8.72 mL of 20% potassium chloride solution (the molar ratio of sodium tetraphenylborate to potassium chloride is 1:2) to the reaction system, control the stirring rate at 150 rpm, mix it thoroughly, and perform precipitation reaction for 1 hour. After the precipitation reaction is completed, filter while hot and collect the filtrate.

[0040] (4) Desalting the filtrate in step (3). Specifically, a cation exchange resin column and an anion exchange resin column are connected in series, the filtrate is adjusted to pH 5.0 by adding sodium hydroxide at room temperature, and first enters the cation exchange resin column at a flow rate of 2 BV / h. The material at the outlet of the cation exchange resin column enters the anion exchange resin column, and the material at the outlet of the anion exchange resin column is collected; when the conductivity of the material at the outlet of the anion exchange resin column is less than 50 μs / cm, the feeding is stopped and the ion exchange resin is regenerated.

[0041] (5) The separated desalted liquid is concentrated by a rotary evaporator under the conditions of a water bath temperature of 80° C. and a negative pressure of -0.088 MPa to 20% of the original volume. After the concentration is completed, the concentrated liquid is freeze-dried to finally obtain a powdery high-purity γ-cyclodextrin product.

[0042] The experimental results showed that the purity of γ-cyclodextrin reached 95.21%, the recovery rate was 90.52%, and the residual amount of sodium tetraphenylborate was 0.02%.

[0043] Example 2

[0044] The difference between this embodiment and embodiment 1 is that 8.72 mL of 20% potassium chloride solution is gradually added at 50° C. in step (3), and the rest of the preparation process is the same as that of embodiment 1.

[0045] Example 3

[0046] The difference between this embodiment and embodiment 1 is that 8.72 mL of 20% potassium chloride solution is gradually added at 70° C. in step (3), and the rest of the preparation process is the same as that of embodiment 1.

[0047] Example 4

[0048] The difference between this embodiment and embodiment 1 is that 11.48 mL of 20% potassium acetate solution (the molar ratio of sodium tetraphenylborate to potassium acetate is 1:2) is gradually added in step (3), and the rest of the preparation process is the same as that of embodiment 1.

[0049] Example 5

[0050] The difference between this embodiment and embodiment 1 is that 6.56 mL of 20% potassium hydroxide solution (the molar ratio of sodium tetraphenylborate to potassium hydroxide is 1:2) is gradually added in step (3), and the rest of the preparation process is the same as that of embodiment 1.

[0051] Example 6

[0052] The difference between this embodiment and embodiment 1 is that the dilution process is not performed in step (2), and the rest of the preparation process is the same as that of embodiment 1.

[0053] Example 7

[0054] The difference between this embodiment and embodiment 1 is that the dilution factor in step (2) is adjusted to 2 times, and the rest of the preparation process is the same as that of embodiment 1.

[0055] Example 8

[0056] The difference between this embodiment and embodiment 1 is that 2.18 mL of 20% potassium chloride solution (the molar ratio of sodium tetraphenylborate to potassium chloride is 2:1) is gradually added in step (3), and the rest of the preparation process is the same as that of embodiment 1.

[0057] Example 9

[0058] The difference between this embodiment and embodiment 1 is that 4.36 mL of 20% potassium chloride solution (the molar ratio of sodium tetraphenylborate to potassium chloride is 1:1) is gradually added in step (3), and the rest of the preparation process is the same as that of embodiment 1.

[0059] Table 2 Separation of γ-cyclodextrin under different embodiments

[0060]

[0061]

[0062] Table 2 shows that temperature, type of precipitant and dilution multiple have significant effects on the recovery rate and purity of γ-cyclodextrin. Specifically, the increase in temperature can significantly improve the recovery rate and purity of γ-cyclodextrin. High temperature helps the dissociation of sodium tetraphenylborate, thereby promoting separation; the selection of different precipitants affects the purity and recovery rate of the final product, among which potassium chloride shows a better effect as a precipitant; the appropriate dilution multiple can significantly improve the separation effect and help the dissociation and precipitation of the reaction aid. At higher temperatures (such as 90°C), the complex of γ-cyclodextrin and sodium tetraphenylborate is easier to dissociate. High temperature increases the molecular kinetic energy and weakens the weak intermolecular interactions within the complex, thereby breaking the combination of γ-cyclodextrin and sodium tetraphenylborate and releasing sodium tetraphenylborate. An appropriate dilution multiple (such as 5 times) reduces the ion concentration in the system, weakens the stability of the complex of sodium tetraphenylborate and γ-cyclodextrin, makes γ-cyclodextrin easier to dissociate and release sodium tetraphenylborate. When the dilution factor is low (such as no dilution or 2-fold dilution), the ion concentration in the solution is high, the stability of the complex is enhanced, and sodium tetraphenylborate is difficult to be completely separated, which reduces the separation effect. At a higher dilution factor, the dissociation of the complex is enhanced, and K + It is easier to form precipitation with sodium tetraphenylborate. Therefore, appropriate dilution and temperature can optimize the reaction conditions and effectively improve the separation efficiency and purity of γ-cyclodextrin.

[0063] Comparative Example 1

[0064] A 15% (w / w) dry cassava starch solution was used as the substrate, and the slurry was first adjusted at 55°C for 10 minutes. Then, γ-cyclodextrin glucosyltransferase was added, and the amount of enzyme added was 3U enzyme solution / g starch. The mixture was heated to 90°C to gelatinize and liquefy the starch. Next, the enzyme was inactivated at 90°C for 30 minutes, and then the temperature was lowered to 55°C. At 55°C, γ-cyclodextrin glucosyltransferase was added to the reaction system again, and the amount of enzyme added was 5U enzyme solution / g starch. At the same time, ultrapure water equivalent to 2% of the total mass of the system was added as a control to carry out a cyclization reaction. After 12 hours of reaction, the enzyme was inactivated in a boiling water bath for 30 minutes to obtain the stock solution to be treated.

[0065] Comparative Example 2

[0066] (1) A 15% (w / w) dry cassava starch solution was used as the substrate and the slurry was first slurried at 55°C for 10 min. Then, γ-cyclodextrin glucosyltransferase was added at a rate of 3U enzyme solution / g starch, and the mixture was heated to 90°C to gelatinize and liquefy the starch. Next, the enzyme was inactivated at 90°C for 30 min, and then the temperature was lowered to 55°C. At 55°C, γ-cyclodextrin glucosyltransferase was added to the reaction system again at a rate of 5U enzyme solution / g starch, and a reaction aid cyclododecanone was added at a rate of 2% of the total mass of the system to carry out a cyclization reaction. After 12 h of reaction, the enzyme was inactivated in a boiling water bath for 30 min to obtain the stock solution to be treated.

[0067] (2) After the original solution to be treated is diluted 2 times with pure water, the cyclododecanone is evaporated using a steam distillation device, the distillate is collected, and the distillate is concentrated to the original volume using a rotary evaporator.

[0068] Comparative Example 3

[0069] The difference between this comparative example and comparative example 2 is that the reaction auxiliary agent in step (1) is changed to 5-cyclohexadecene-1-one, and the rest of the preparation process is the same as that of comparative example 2.

[0070] Comparative Example 4

[0071] The difference between this comparative example and comparative example 2 is that the reaction auxiliary agent in step (1) is changed to cyclopentadecanone, and the rest of the preparation process is the same as that of comparative example 2.

[0072] Comparative Example 5

[0073] The difference between this comparative example and comparative example 2 is that the reaction aid in step (1) is changed to potassium tetraphenylborate, and the rest of the preparation process is the same as that of comparative example 2.

[0074] Comparative Example 6

[0075] The difference between this comparative example and Example 1 is that in step (3), 8.72 mL of 20% concentration potassium chloride solution (the molar ratio of sodium tetraphenylborate to potassium chloride is 1:2) is gradually added at room temperature 25°C.

[0076] The recovery rate of γ-cyclodextrin obtained in Comparative Example 6 is only 1.2%. This shows that at room temperature, the structure of the complex formed by γ-cyclodextrin and the reaction aid is stable, and the effect of precipitation separation is not good. Under high temperature conditions (such as 90°C in Example 1), the structure of the complex can be destroyed, the reaction aid is released, and γ-cyclodextrin can be effectively separated after adding the precipitant. Therefore, the precipitation reaction at room temperature cannot effectively remove the reaction aid, resulting in a significant reduction in the recovery rate of γ-cyclodextrin.

[0077] Comparative Example 7

[0078] The difference between this comparative example and Example 1 is that the step (3) is adjusted to gradually add 6.84 mL of 20% sodium chloride solution (the molar ratio of sodium tetraphenylborate to sodium chloride is 1:2) at 90°C, and the rest of the preparation process is the same as Example 1.

[0079] Comparative Example 8

[0080] The difference between this comparative example and Example 1 is that the step (3) is adjusted to add 12.98 mL of 20% concentration calcium chloride solution (the molar ratio of sodium tetraphenylborate to calcium chloride is 1:2) at 90° C., and the rest of the preparation process is the same as Example 1.

[0081] Table 3 Conversion rate and separation of γ-cyclodextrin under different comparative examples

[0082]

[0083] Note: (ND = not dected)

[0084] As shown in Table 3, when different reaction aids are used, the conversion rate and recovery rate of γ-cyclodextrin show differences. For example, the γ-cyclodextrin recovery rate of large-ring reaction aids such as cyclododecanone, 5-cyclohexadecene-1-one, and cyclopentadecanone reaches more than 85%, but the product purity and conversion rate are low. Potassium tetraphenylborate has no significant effect on the production of the system, but sodium tetraphenylborate can increase the conversion rate of γ-cyclodextrin by 169.7%, and its residual amount after separation is only 0.02%. Under different temperatures, the recovery rate and purity of γ-cyclodextrin show large differences. The recovery rate of comparative example 6 (reacting at room temperature) is only 1.2%, while the recovery rate of the reaction under 90°C conditions is significantly improved. This shows that temperature is an important factor affecting the separation and purification of γ-cyclodextrin. High temperature can effectively promote the dissociation of the complex, so that sodium tetraphenylborate generates precipitation and separates it, which improves the purity of γ-cyclodextrin. Compared with other sodium and calcium ions, potassium ions have the best effect in the separation process. Sodium and calcium ions have low reactivity and are difficult to form stable precipitates, resulting in reduced separation efficiency and product purity. The unique chemical reactivity of potassium ions ensures the efficiency of sodium tetraphenylborate precipitation separation, making it a better choice of precipitant.

[0085] Figure 1 The HPLC spectrum of the treated stock solution obtained when 15% cassava starch was used as the substrate is shown. Figure 1 It can be observed that there are multiple peaks in the stock solution, showing the complex components in the system, including the target product γ-cyclodextrin and the reaction aid sodium tetraphenylborate. This result shows that before precipitation separation, the impurity content in the system is high and further purification is required to obtain high-purity γ-cyclodextrin. Figure 2 Shown is the HPLC profile of γ-cyclodextrin after precipitation. Figure 1 compared to, Figure 2 The peak of γ-cyclodextrin was significantly enhanced, and the peak of sodium tetraphenylborate basically disappeared, which shows that potassium chloride was used as a precipitant to generate precipitation through the dissociation reaction of sodium tetraphenylborate under high temperature conditions, removing unwanted byproducts in the system and achieving a significant purification effect. This method is not only simple and easy to operate, but also helps to improve the purity and recovery rate of the product, and is suitable for large-scale application. Figure 3 and Figure 4 The results of the above studies have verified the importance of optimizing the potassium ion molar ratio and reaction temperature for the separation of γ-cyclodextrin. Figure 4 In the experiment, when the molar ratio of potassium ion to sodium tetraphenylborate was 1:2, the separation effect was the best, indicating that the potassium ion supply at this ratio was most suitable for precipitation formation. Figure 3In the experiment, high temperature (such as 90°C) promoted the dissociation of the complex and helped potassium ions to form efficient precipitation, maximizing the purity and recovery rate of γ-cyclodextrin. Overall, the combination of suitable potassium ion ratio and high temperature conditions provided an optimized solution for improving the separation purity and recovery rate of γ-cyclodextrin. This method is suitable for promotion and application in industrialization.

[0086] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the present invention can be modified or replaced by equivalents without departing from the spirit and scope of the technical solutions of the present invention, which should all be included in the scope of the present invention.

Claims

1. A method for preparing γ-cyclodextrin by separation and enzymatic method using precipitation technology, characterized in that: include, The complex formed by gamma-cyclodextrin and a reaction aid is diluted and dissociated at high temperature, a precipitant is added, stirred and filtered to obtain a solution, an ion exchange resin is used to desalt the solution, and the solution is concentrated and dried to obtain high-purity gamma-cyclodextrin.

2. The method according to claim 1, characterized in that: The precipitant is a soluble potassium salt solution, including one or more of potassium phosphate, potassium hydroxide, potassium acetate, potassium chloride solution, and potassium dihydrogen phosphate.

3. The method according to claim 1, characterized in that: The reaction aid is a phenyl-substituted borate or a phenyl-substituted borate derivative, including one or more of 2-fluorophenylboric acid, methylphenylboric acid, 4-nitrophenylboric acid, and sodium tetraphenylborate.

4. The method according to claim 1, characterized in that: The complex formed by gamma-cyclodextrin and the reaction aid is diluted and dissociated at high temperature, wherein the dilution multiple is 2 to 10 times, the temperature is 60 to 95° C., and the time is 1 to 2 hours.

5. The method according to claim 2, characterized in that: The concentration of the precipitant is 20-50%.

6. The method according to claim 5, characterized in that: The precipitant is added and stirred, wherein the stirring temperature is 70-95° C., the stirring speed is 150-200 rpm, and the time is 1-60 min.

7. The method according to claim 1, characterized in that: The ion exchange resin includes anion exchange resin and cation exchange resin, wherein the anion exchange resin includes a macroporous weak base styrene anion exchange resin, and the cation exchange resin includes a macroporous strong acid styrene cation exchange resin.

8. The method according to claim 1, characterized in that: The desalination treatment conditions are as follows: the conductivity of the material at the outlet of the ion exchange resin column is less than 50 μs / cm, the feeding is stopped to regenerate the ion exchange resin; the temperature of the filtrate is 10-50° C., the pH is 4.0-8.0, and the injection flow rate is 1-2 BV / h.

9. γ-cyclodextrin obtained by the method according to claims 1 to 8.

10. The γ-cyclodextrin according to claim 9, characterized in that: The recovery rate of the gamma-cyclodextrin is 82.76% to 90.84%, and the purity is 92.56% to 95.63%.

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