Polymerization process method of high-purity sugar-free sodium-free polydextrose

Abstract

The invention relates to the technical field of polydextrose, in particular to a polymerization process method of high-purity sugar-free sodium-free polydextrose, which comprises the following steps of: preparing raw materials which comprise glucose, citric acid and sorbitol in percentage by weight: 10 to 14 percent of sorbitol, 1.4 to 1.6 percent of citric acid and the balance of glucose; raw material pretreatment: glucose and sorbitol in the raw materials are respectively pretreated, the glucose is pretreated to obtain a first base material, and the sorbitol is pretreated to obtain a second base material; according to the invention, the polymerization reaction adopts micro-channel polymerization to replace the traditional reaction kettle polymerization mode, the polymerization reaction can realize continuous flow reaction, the liquid holdup in the reaction process is low, the micro-channel reactor can strictly control the reaction temperature, residence time and material ratio, and meanwhile, the method has the advantages of high mass and heat transfer efficiency, easiness in control, energy conservation and environmental protection; the yield and the purity of a polydextrose product are effectively improved.

Description

Technical Field

[0001] The invention relates to the technical field of polydextrose, in particular to a polymerization process method of high-purity sugar-free and sodium-free polydextrose. Background Art

[0002] Polydextrose is a water-soluble dietary fiber, which is polymerized by high temperature from glucose, sorbitol and citric acid. It is a white or off-white powder, odorless and slightly sweet. It has the characteristics of low calories and is not digested and absorbed by the human body. It can regulate intestinal flora, reduce blood lipids, and increase satiety. It is widely used in food, health care products and other fields.

[0003] In the prior art, the existing polydextrose products have defects in their production process, which easily leads to the problem of uneven polymerization temperature, thereby affecting the purity of the polydextrose products. Based on this, the present invention provides a polymerization process method for high-purity sugar-free and sodium-free polydextrose. Summary of the invention

[0004] The purpose of the present invention is to provide a polymerization process method for high-purity sugar-free and sodium-free polydextrose. The polydextrose prepared by the present invention not only has good purity performance, but also has excellent gloss performance.

[0005] To achieve the above object, the present invention provides the following technical solution: a polymerization process for high-purity sugar-free and sodium-free polydextrose, comprising the following steps: S1: raw material preparation, the raw materials include glucose, citric acid and sorbitol, the weight percentage of each raw material is: 10-14% sorbitol and 1.4-1.6% citric acid, and the balance is glucose; S2: raw material pretreatment, respectively pretreating glucose and sorbitol in the raw material, obtaining a first base material after glucose is pretreated, and obtaining a second base material after sorbitol is pretreated; S3: polymer preparation: after mixing the first base material, the second base material and citric acid, a polymer is prepared by using microchannel reaction technology; S4: catalytic treatment: adding purified water to the polymer and mixing, and then adding a catalyst to perform a reaction treatment to obtain a first mixed solution; S5: decolorization treatment: the first mixed solution is mixed with an equal amount of pure water in S4, mixed with an adsorbent, and subjected to heat preservation and decolorization treatment to obtain a second mixed solution; S6: sodium removal treatment, the second mixed solution is dialyzed to complete sodium removal, and a slurry is obtained; S7: Preparation: The slurry is concentrated and dried to obtain high-purity sugar-free and sodium-free polydextrose.

[0006] Furthermore, the glucose pretreatment method is as follows: glucose is added to a flask, pyridine is added to the flask, acetic anhydride is added dropwise after mixing, stirring is continued during the dropping process, and after mixing, the mixture is stirred and mixed at 26 to 30° C. for 2 to 3 hours. After the stirring and mixing is completed, the product in the flask is added to a rotary evaporator for distillation treatment. The rotary evaporator is set at a pressure of 20 to 40 mbar, a speed of 60 to 80 r / min, and a temperature of 40 to 60° C. After the distillation treatment, pyridine and acetic anhydride are removed, and the obtained product is filtered, washed, and dried to obtain the first base material.

[0007] Furthermore, the mass of the pyridine is 60-80% of the mass of glucose, and the mass of the acetic anhydride is 40-60% of the mass of glucose.

[0008] Furthermore, the pretreatment method of sorbitol is as follows: sorbitol and water are added to a reactor and mixed, the reactor is set to be heated to 45-55°C, the rotation speed is 120-160 r / min, and the heat preservation and stirring treatment is performed for 6-10 minutes. After the heat preservation and stirring treatment is completed, boric acid is added, the temperature is set to 38-42°C, the rotation speed is 80-100 r / min, and the heat preservation and stirring treatment is performed for 20-30 minutes. The product obtained in the reactor is washed and dried to obtain a second base material.

[0009] Furthermore, the mass ratio of sorbitol to water is 1:(0.3-0.5), and the mass of the boric acid is 0.6-0.8% of the mass of sorbitol.

[0010] Furthermore, the method for preparing the polymer is: the first base material, the second base material, and citric acid are added to a mixer, deionized water is added to the mixer for stirring, the product obtained by the stirring treatment is added to a microchannel reactor for treatment, and the product obtained by the treatment is subjected to vacuum freeze-drying treatment to obtain a powdered polymer.

[0011] Furthermore, the mass of the deionized water is 40-60% of the mass of the first base material, and the mixer is set at 100-200 r / min for stirring for 10-20 minutes.

[0012] Furthermore, the microchannel reactor is set at a temperature of 120-140° C., a pressure of 0.6-1.2 MPa, a treatment time of 12-14 min, and a cooling rate of 30-40° C. / s after the treatment time is completed.

[0013] Furthermore, the catalytic treatment method is: the mass ratio of the polymer to pure water is 1: (1.6-1.8), the mixed product is added to a reactor, the pH is adjusted to 8-12, a catalyst is added to the reactor, the temperature is set to 120-140°C, the pressure is 4-8MPa, and the hydrogenation reaction is performed for 3-4 hours to obtain a first mixed liquid, wherein the mass of the catalyst is 4-6% of the mass of the polymer, and the catalyst is selected from Raney nickel, and the mass of the adsorbent is 2-4% of the mass of the first mixed liquid, and the adsorbent is selected from diatomaceous earth.

[0014] Furthermore, the method for removing the sodium radical is as follows: the second mixed liquid is added to a dialysis bag, the dialysis bag has a molecular weight cutoff of 500Da, the dialysis bag is immersed in the dialysis solution, and the dialysis bag is slowly shaken for 4 to 6 hours using a shaker, and the product obtained in the dialysis bag is mixed with pure water of 0.4 to 0.6 times its mass to obtain a slurry.

[0015] Compared with the prior art, the present invention has the following beneficial effects: 1. In the present invention, the polymerization of raw materials is treated by adopting microchannel reaction technology. The polymerization reaction replaces the traditional reactor polymerization method with microchannel polymerization. The polymerization reaction can realize continuous flow reaction. The liquid holding volume is low during the reaction process. The microchannel reactor can strictly control the reaction temperature, residence time and material ratio. At the same time, it has the advantages of high mass and heat transfer efficiency, easy control, energy saving and environmental protection, and effectively improves the yield and purity of the polydextrose product.

[0016] 2. In the present invention, during the preparation of polydextrose, after glucose is modified by acetylation, an acetyl group is introduced into the molecular structure, thereby changing the activity and steric hindrance of the original hydroxyl group. This enhances the reaction activity of glucose in the reaction of preparing polydextrose, reduces the occurrence of unnecessary side reactions, and helps to improve the polymerization degree and output rate of polydextrose, thereby effectively improving the purity performance of the polydextrose product.

[0017] 3. In the present invention, by pre-treating sorbitol, boric acid can form a complex with sorbitol. The formation of this complex changes the electron cloud distribution of sorbitol, thereby improving the reaction activity of sorbitol. During the polymerization reaction, sorbitol is more likely to undergo a condensation reaction with glucose, thereby effectively improving the reaction rate and the yield of polydextrose. DETAILED DESCRIPTION

[0018] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments 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.

[0019] It should be noted that the raw materials used in the following examples are all commercially available raw materials.

[0020] Embodiment 1:

[0021] S1: raw material preparation, the raw materials include glucose, citric acid and sorbitol, the weight percentage of each raw material is: 10% sorbitol and 1.4% citric acid, and the balance is glucose; S2: raw material pretreatment, respectively pretreating glucose and sorbitol in the raw material, obtaining a first base material after glucose is pretreated, and obtaining a second base material after sorbitol is pretreated; The pretreatment method of glucose is as follows: glucose is added into a flask, pyridine is added into the flask, acetic anhydride is added dropwise after mixing, stirring is continuously maintained during the dropping process, mixing is performed at 26° C. for 2 hours, and after the stirring and mixing is completed, the product in the flask is added into a rotary evaporator for distillation treatment, and the rotary evaporator is set at a pressure of 20 mbar, a speed of 60 r / min, and a temperature of 40° C. After the distillation treatment, pyridine and acetic anhydride are removed, and the obtained product is filtered, washed, and dried to obtain a first base material, wherein the mass of pyridine is 60% of the mass of glucose, and the mass of acetic anhydride is 40% of the mass of glucose; The pretreatment method of sorbitol is as follows: sorbitol and water are added to a reactor and mixed, the reactor is set to be heated to 45°C, the speed is 120r / min, and the heat preservation and stirring treatment is performed for 6 minutes, after the heat preservation and stirring treatment is completed, boric acid is added, the temperature is set to 38°C, the speed is 80r / min, and the heat preservation and stirring treatment is performed for 20 minutes, the product obtained in the reactor is washed and dried to obtain a second base material, the mass ratio of sorbitol to water is 1:0.3, and the mass of the boric acid is 0.6% of the mass of sorbitol; S3: polymer preparation: after mixing the first base material, the second base material and citric acid, a polymer is prepared by using microchannel reaction technology; The method for preparing the polymer is as follows: a first base material, a second base material and citric acid are added to a mixer, deionized water is added to the mixer for stirring, a product obtained by the stirring is added to a microchannel reactor for treatment, and the product obtained by the treatment is subjected to vacuum freeze drying to obtain a powdered polymer, the mass of the deionized water is 40% of the mass of the first base material, the mixer is set at 100 r / min for stirring for 10 minutes, the microchannel reactor is set at a temperature of 120° C., a pressure of 0.6 MPa, a treatment time of 12 minutes, and a cooling rate of 30° C. / s after the treatment time ends; S4: catalytic treatment: adding purified water to the polymer and mixing, and then adding a catalyst to perform a reaction treatment to obtain a first mixed solution; The catalytic treatment method is as follows: the mass ratio of polymer to pure water is 1:1.6, the mixed product is added into a reactor, the pH is adjusted to 8, a catalyst is added into the reactor, the temperature is set to 120°C, the pressure is 4MPa, and the hydrogenation reaction is performed for 3h to obtain a first mixed solution, wherein the mass of the catalyst is 4% of the mass of the polymer, and the catalyst is selected from Raney nickel; S5: decolorization treatment: the first mixed solution is mixed with an equal amount of pure water in S4, mixed with an adsorbent, and subjected to heat preservation and decolorization treatment to obtain a second mixed solution; The mass of the adsorbent is 2% of the mass of the first mixed liquid, and diatomaceous earth is selected as the adsorbent; S6: sodium removal treatment, the second mixed solution is dialyzed to complete sodium removal, and a slurry is obtained; The method of removing the sodium is as follows: the second mixed solution is added to a dialysis bag, the molecular weight cutoff of the dialysis bag is 500Da, the dialysis bag is immersed in the dialysis solution, and the dialysis bag is slowly shaken for 4 hours using a shaker, and the product obtained in the dialysis bag is mixed with pure water of 0.4 times its mass to obtain a slurry; S7: Preparation: The slurry is concentrated and dried to obtain high-purity sugar-free and sodium-free polydextrose.

[0022] Embodiment 2:

[0023] S1: raw material preparation, the raw materials include glucose, citric acid and sorbitol, the weight percentage of each raw material is: 12% sorbitol and 1.5% citric acid, and the balance is glucose; S2: raw material pretreatment, respectively pretreating glucose and sorbitol in the raw material, obtaining a first base material after glucose is pretreated, and obtaining a second base material after sorbitol is pretreated; The pretreatment method of glucose is as follows: glucose is added into a flask, pyridine is added into the flask, acetic anhydride is added dropwise after mixing, stirring is continued during the dropping process, mixing is performed at 28° C. for 2.5 hours, after the stirring and mixing is completed, the product in the flask is added into a rotary evaporator for distillation treatment, the rotary evaporator is set at a pressure of 30 mbar, a speed of 70 r / min, and a temperature of 50° C. After the distillation treatment, pyridine and acetic anhydride are removed, and the obtained product is filtered, washed, and dried to obtain a first base material, wherein the mass of pyridine is 70% of the mass of glucose, and the mass of acetic anhydride is 50% of the mass of glucose; The pretreatment method of sorbitol is as follows: sorbitol and water are added to a reactor and mixed, the reactor is set to be heated to 50°C, the speed is 140r / min, and the heat preservation and stirring treatment is performed for 8 minutes, after the heat preservation and stirring treatment is completed, boric acid is added, the temperature is set to 40°C, the speed is 90r / min, and the heat preservation and stirring treatment is performed for 25 minutes, the product obtained in the reactor is washed and dried to obtain a second base material, the mass ratio of sorbitol to water is 1:0.4, and the mass of the boric acid is 0.7% of the mass of sorbitol; S3: polymer preparation: after mixing the first base material, the second base material and citric acid, a polymer is prepared by using microchannel reaction technology; The method for preparing the polymer is as follows: a first base material, a second base material and citric acid are added to a mixer, deionized water is added to the mixer for stirring, a product obtained by the stirring is added to a microchannel reactor for treatment, and the product obtained by the treatment is subjected to vacuum freeze drying to obtain a powdered polymer, the mass of the deionized water is 50% of the mass of the first base material, the mixer is set to stir at 150 r / min for 15 minutes, the microchannel reactor is set to a temperature of 130° C., a pressure of 0.9 MPa, a treatment time of 13 minutes, and a cooling rate after the treatment time is set to 35° C. / s; S4: catalytic treatment: adding purified water to the polymer and mixing, and then adding a catalyst to perform a reaction treatment to obtain a first mixed solution; The catalytic treatment method is as follows: the mass ratio of polymer to pure water is 1:1.7, the mixed product is added into a reactor, the pH is adjusted to 10, a catalyst is added into the reactor, the temperature is set to 130°C, the pressure is 6MPa, and the hydrogenation reaction is performed for 3.5h to obtain a first mixed solution, wherein the mass of the catalyst is 5% of the mass of the polymer, and the catalyst is selected from Raney nickel; S5: decolorization treatment: the first mixed solution is mixed with an equal amount of pure water in S4, mixed with an adsorbent, and subjected to heat preservation and decolorization treatment to obtain a second mixed solution; The mass of the adsorbent is 3% of the mass of the first mixed liquid, and diatomaceous earth is selected as the adsorbent; S6: sodium removal treatment, the second mixed solution is dialyzed to complete sodium removal, and a slurry is obtained; The method of removing the sodium is as follows: the second mixed solution is added to a dialysis bag, the molecular weight cutoff of the dialysis bag is 500Da, the dialysis bag is immersed in the dialysis solution, and the dialysis bag is slowly shaken for 5 hours using a shaker, and the product obtained in the dialysis bag is mixed with pure water of 0.5 times its mass to obtain a slurry; S7: Preparation: The slurry is concentrated and dried to obtain high-purity sugar-free and sodium-free polydextrose.

[0024] Embodiment three:

[0025] S1: raw material preparation, the raw materials include glucose, citric acid and sorbitol, the weight percentage of each raw material is: 14% sorbitol and 1.6% citric acid, and the balance is glucose; S2: raw material pretreatment, respectively pretreating glucose and sorbitol in the raw material, obtaining a first base material after glucose is pretreated, and obtaining a second base material after sorbitol is pretreated; The pretreatment method of glucose is as follows: glucose is added into a flask, pyridine is added into the flask, acetic anhydride is added dropwise after mixing, stirring is continuously maintained during the dropping process, mixing is performed at 30° C. for 3 hours, and after the stirring and mixing is completed, the product in the flask is added into a rotary evaporator for distillation treatment, and the rotary evaporator is set at a pressure of 40 mbar, a speed of 80 r / min, and a temperature of 60° C. After the distillation treatment, pyridine and acetic anhydride are removed, and the obtained product is filtered, washed, and dried to obtain a first base material, wherein the mass of pyridine is 80% of the mass of glucose, and the mass of acetic anhydride is 60% of the mass of glucose; The pretreatment method of sorbitol is as follows: sorbitol and water are added to a reactor and mixed, the reactor is set to be heated to 55°C, the speed is 160r / min, and the mixture is kept warm and stirred for 10 minutes. After the heat preservation and stirring treatment is completed, boric acid is added, the temperature is set to 42°C, the speed is 100r / min, and the mixture is kept warm and stirred for 30 minutes. The product obtained in the reactor is washed and dried to obtain a second base material, the mass ratio of sorbitol to water is 1:0.5, and the mass of the boric acid is 0.8% of the mass of sorbitol. S3: polymer preparation: after mixing the first base material, the second base material and citric acid, a polymer is prepared by using microchannel reaction technology; The method for preparing the polymer is as follows: a first base material, a second base material and citric acid are added to a mixer, deionized water is added to the mixer for stirring, a product obtained by the stirring is added to a microchannel reactor for treatment, and the product obtained by the treatment is subjected to vacuum freeze drying to obtain a powdered polymer, the mass of the deionized water is 60% of the mass of the first base material, the mixer is set at 200 r / min for stirring for 20 minutes, the microchannel reactor is set at a temperature of 140° C., a pressure of 1.2 MPa, a treatment time of 14 minutes, and a cooling rate of 40° C. / s after the treatment time ends; S4: catalytic treatment: adding purified water to the polymer and mixing, and then adding a catalyst to perform a reaction treatment to obtain a first mixed solution; The catalytic treatment method is as follows: the mass ratio of polymer to pure water is 1:1.8, the mixed product is added into a reactor, the pH is adjusted to 12, a catalyst is added into the reactor, the temperature is set to 140°C, the pressure is 8MPa, and the hydrogenation reaction is performed for 4 hours to obtain a first mixed solution, wherein the mass of the catalyst is 6% of the mass of the polymer, and the catalyst is selected from Raney nickel; S5: decolorization treatment: the first mixed solution is mixed with an equal amount of pure water in S4, mixed with an adsorbent, and subjected to heat preservation and decolorization treatment to obtain a second mixed solution; The mass of the adsorbent is 4% of the mass of the first mixed liquid, and diatomaceous earth is selected as the adsorbent; S6: sodium removal treatment, the second mixed solution is dialyzed to complete sodium removal, and a slurry is obtained; The method of removing the sodium is as follows: the second mixed solution is added to a dialysis bag, the molecular weight cutoff of the dialysis bag is 500Da, the dialysis bag is immersed in the dialysis solution, and the dialysis bag is slowly shaken for 6 hours using a shaker, and the product obtained in the dialysis bag is mixed with pure water of 0.6 times its mass to obtain a slurry; S7: Preparation: The slurry is concentrated and dried to obtain high-purity sugar-free and sodium-free polydextrose.

[0026] Comparative Example 1 The difference between this comparative example and Example 1 is that no catalytic treatment is performed in this comparative example.

[0027] Comparative Example 2 The difference between this comparative example and Example 1 is that: in this comparative example, reactor polymerization is used instead of microchannel reactor polymerization, wherein the temperature of the reactor polymerization treatment is 140° C., and the treatment time is 15 min.

[0028] Comparative Example 3 The difference between this comparative example and Example 1 is that sorbitol is not pretreated in this comparative example.

[0029] Comparative Example 4 The difference between this comparative example and Example 1 is that glucose is not pretreated in this comparative example.

[0030] Performance test: The performance test was performed on the polydextrose prepared in Example 1, Example 2, Example 3, Comparative Example 1, Comparative Example 2, Comparative Example 3 and Comparative Example 4, and the obtained test data were recorded in the following table:

[0031] It can be seen that the purity performance and glossiness performance of the polydextrose prepared in Comparative Examples 1, 2, 3, and 4 are lower than those in Examples 1, 2, and 3; this shows that: by adopting the microchannel reaction technology to polymerize the raw materials, the polymerization reaction replaces the traditional reactor polymerization method with microchannel polymerization, the polymerization reaction can realize continuous flow reaction, the liquid holding volume is low during the reaction process, and the microchannel reactor can strictly control the reaction temperature, residence time, and material ratio. At the same time, it has the advantages of high mass transfer and heat transfer efficiency, easy control, energy saving and environmental protection, which effectively improves the yield and purity performance of the polydextrose product. In the preparation process of polydextrose, glucose is acetylated After chemical modification, acetyl groups are introduced into the molecular structure, changing the activity and steric hindrance of the original hydroxyl group. This enhances the reactivity of glucose in the preparation of polydextrose, reduces its unnecessary side reactions, helps to improve the polymerization degree and yield of polydextrose, and thus effectively improves the purity performance of the polydextrose product. Through the pretreatment of sorbitol, boric acid can form a complex with sorbitol. The formation of this complex changes the electron cloud distribution of sorbitol, thereby increasing the reactivity of sorbitol. During the polymerization reaction, sorbitol is more likely to undergo a condensation reaction with glucose, effectively increasing the reaction rate and the yield of polydextrose.

[0032] By comparing and analyzing the relevant data in the table, it can be seen that the polydextrose prepared by the present invention not only has good purity performance, but also has excellent gloss performance. This shows that the polymerization process of high-purity sugar-free and sodium-free polydextrose provided by the present invention has a broader market prospect and is more suitable for promotion.

[0033] In the description of this specification, the description with reference to the terms "one embodiment", "example", "specific example", etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner.

[0034] The preferred embodiments of the present invention disclosed above are only used to help illustrate the present invention. The preferred embodiments do not describe all the details in detail, nor do they limit the invention to the specific implementation methods described. Obviously, many modifications and changes can be made according to the content of this specification. This specification selects and specifically describes these embodiments in order to better explain the principles and practical applications of the present invention, so that those skilled in the art can understand and use the present invention well. The present invention is limited only by the claims and their full scope and equivalents.

Claims

1. A polymerization process for high-purity sugar-free and sodium-free polydextrose, characterized in that: The following steps are involved: S1: raw material preparation, the raw materials include glucose, citric acid and sorbitol, the weight percentage of each raw material is: 10-14% sorbitol and 1.4-1.6% citric acid, and the balance is glucose; S2: raw material pretreatment, respectively pretreating glucose and sorbitol in the raw material, obtaining a first base material after glucose is pretreated, and obtaining a second base material after sorbitol is pretreated; S3: polymer preparation: after mixing the first base material, the second base material and citric acid, a polymer is prepared by using microchannel reaction technology; S4: catalytic treatment: adding purified water to the polymer and mixing, and then adding a catalyst to perform a reaction treatment to obtain a first mixed solution; S5: decolorization treatment: the first mixed solution is mixed with an equal amount of pure water in S4, mixed with an adsorbent, and subjected to heat preservation and decolorization treatment to obtain a second mixed solution; S6: sodium removal treatment, the second mixed solution is dialyzed to complete sodium removal, and a slurry is obtained; S7: Preparation: The slurry is concentrated and dried to obtain high-purity sugar-free and sodium-free polydextrose.

2. The polymerization process of high-purity sugar-free and sodium-free polydextrose according to claim 1, characterized in that: The glucose pretreatment method is as follows: glucose is added into a flask, pyridine is added into the flask, acetic anhydride is added dropwise after mixing, stirring is maintained during the dropping process, mixing is performed at 26-30° C. for 2-3 hours, after the stirring and mixing is completed, the product in the flask is added into a rotary evaporator for distillation treatment, the rotary evaporator is set with a pressure of 20-40 mbar, a rotation speed of 60-80 r / min, and a temperature of 40-60° C., pyridine and acetic anhydride are removed after distillation treatment, and the obtained product is filtered, washed, and dried to obtain the first base material.

3. The polymerization process of high-purity sugar-free and sodium-free polydextrose according to claim 2, characterized in that: The mass of the pyridine is 60-80% of the mass of the glucose, and the mass of the acetic anhydride is 40-60% of the mass of the glucose.

4. The polymerization process of high-purity sugar-free and sodium-free polydextrose according to claim 1, characterized in that: The sorbitol pretreatment method is as follows: sorbitol and water are added into a reaction kettle and mixed, the temperature of the reaction kettle is set to 45-55° C., the rotation speed is 120-160 r / min, and the reaction kettle is kept warm and stirred for 6-10 minutes, after the heat preservation and stirring treatment is completed, boric acid is added, the temperature is set to 38-42° C., the rotation speed is 80-100 r / min, and the heat preservation and stirring treatment is carried out for 20-30 minutes, and the product obtained in the reaction kettle is washed and dried to obtain the second base material.

5. The polymerization process of high-purity sugar-free and sodium-free polydextrose according to claim 4, characterized in that: The mass ratio of sorbitol to water is 1:(0.3-0.5), and the mass of the boric acid is 0.6-0.8% of the mass of sorbitol.

6. The polymerization process of high-purity sugar-free and sodium-free polydextrose according to claim 1, characterized in that: The method for preparing the polymer is as follows: the first base material, the second base material and citric acid are added into a mixer, deionized water is added into the mixer for stirring, the product obtained by stirring is added into a microchannel reactor for treatment, and the product obtained by treatment is subjected to vacuum freeze drying to obtain a powdered polymer.

7. The polymerization process of high-purity sugar-free and sodium-free polydextrose according to claim 6, characterized in that: The mass of the deionized water is 40-60% of the mass of the first base material, and the mixer is set at 100-200 r / min for stirring for 10-20 minutes.

8. The polymerization process of high-purity sugar-free and sodium-free polydextrose according to claim 6, characterized in that: The microchannel reactor is set at a temperature of 120-140° C., a pressure of 0.6-1.2 MPa, a treatment time of 12-14 min, and a cooling rate of 30-40° C. / s after the treatment time is completed.

9. The polymerization process of high-purity sugar-free and sodium-free polydextrose according to claim 1, characterized in that: In the S4, the catalytic treatment method is: the mass ratio of polymer to pure water is 1: (1.6-1.8), the mixed product is added to the reactor, the pH is adjusted to 8-12, the catalyst is added to the reactor, the temperature is set to 120-140°C, the pressure is 4-8MPa, and the hydrogenation reaction is carried out for 3-4h to obtain a first mixed liquid, wherein the mass of the catalyst is 4-6% of the mass of the polymer, and the catalyst is selected from Raney nickel. In the S5, the mass of the adsorbent is 2-4% of the mass of the first mixed liquid, and the adsorbent is selected from diatomaceous earth.

10. The polymerization process of high-purity sugar-free and sodium-free polydextrose according to claim 1, characterized in that: The method for removing the sodium content is as follows: the second mixed liquid is added to a dialysis bag with a molecular weight cutoff of 500Da, the dialysis bag is immersed in the dialysis solution, and the dialysis bag is slowly shaken for 4 to 6 hours using a shaker, and the product obtained in the dialysis bag is mixed with pure water with a mass of 0.4 to 0.6 times that of the product to obtain a slurry.

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