CN109438184B - Method for increasing and stabilizing pH of crystal xylitol - Google Patents
Method for increasing and stabilizing pH of crystal xylitol Download PDFInfo
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- CN109438184B CN109438184B CN201811534644.3A CN201811534644A CN109438184B CN 109438184 B CN109438184 B CN 109438184B CN 201811534644 A CN201811534644 A CN 201811534644A CN 109438184 B CN109438184 B CN 109438184B
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Abstract
The invention relates to a method for increasing and stabilizing the pH value of crystalline xylitol, which comprises the following steps: taking 2L of xylitol ion-exchange liquid, passing through 300ml of mixed bed resin, enabling the feeding flow of the xylitol ion-exchange liquid to be 20 ml/min-40 ml/min, processing for 50 min-100 min, collecting 1.5L of mixed bed liquid, then carrying out vacuum concentration on the mixed bed liquid to obtain concentrated liquid, crystallizing the concentrated liquid at 40-50 ℃ for 6-24 h, finally centrifuging and drying to obtain crystalline xylitol; wherein, the mixed bed resin is prepared by uniformly mixing 120ml of D101 type positive resin and 180ml of D201 type negative resin. The invention improves and stabilizes the pH value of the dissolved crystal xylitol through mixed bed resin treatment, and the product is relatively more stable and has more application range.
Description
Technical Field
The invention belongs to the technical field of xylitol preparation, and particularly relates to a method for increasing and stabilizing the pH value of crystalline xylitol.
Background
Xylitol is a white crystal, has the sweetness equivalent to that of cane sugar, has the energy equivalent to that of glucose, has the function of preventing dental caries, does not need insulin for human metabolism, has good effect of improving various diseases, and is applied to a plurality of fields. At present, the production process of xylitol mainly adopts a chemical method, generally takes plant fiber rich in pentosan as a raw material, obtains high-purity xylose through the steps of hydrolysis, purification, ion exchange and the like, then converts the xylose into the xylitol through a chemical hydrogenation reaction, and obtains the crystallized xylitol through refining processes of decoloration, ion exchange, crystallization, centrifugation, drying and the like of the hydrogenated xylitol liquid. Wherein it is important to control and stabilize the pH of the final product throughout the production process, and wherein the process that is decisive for the pH of the final product is the ion exchange step. At present, for conventional products, the mode of ion exchange operation is a positive → negative series connection, the pH of an ion exchange discharge material is controlled to be 4.0-7.5, the conductivity is less than or equal to 50 mu s/cm, and the transmittance is greater than or equal to 95%. The principle of the ion exchange is as follows:
a. basic principle of cation exchange: the hydrogen type cation exchange resin is used for adsorbing cations such as iron, calcium and the like in the feed liquid, thereby achieving the purposes of removing metal cations in the feed liquid and purifying the feed liquid.
b. Basic principle of anion exchange: adsorbing Cl in feed liquid by using oxyhydrogen type anion exchange resin-、SO42-And the anions are treated, so that the aim of removing the anions in the feed liquid and purifying the feed liquid is fulfilled. H accumulated after cation exchange+OH exchanged with anion column-The combination produces water with a very low degree of dissociation.
H due to cation exchange+There is a certain amount of accumulation before reaching the anion column, which causes the cation column to generate counter ion effect, resulting in partial cation not being replaced, so the ion exchange is not very thorough. Meanwhile, the crystal xylitol obtained by the conventional production process of single-group serial discharge at present has unstable pH value which is about 5.0 at times, so that the application of the xylitol is influenced. At present, the pH value of the crystal xylitol obtained by utilizing the conventional production process of the xylitol is between 5.0 and 7.0 after being dissolved, is mostly below 6.0 and sometimes about 5.0, and cannot be applied to xylitol injection and the like. There is therefore a need to find a process which increases and stabilizes the pH of crystalline xylitol.
Disclosure of Invention
The technical problem to be solved by the present invention is to provide a method for raising and stabilizing the pH of crystalline xylitol, which raises and stabilizes the pH of crystalline xylitol after dissolution by mixed bed resin treatment.
The present invention has been accomplished by providing a method for increasing and stabilizing the pH of crystalline xylitol, comprising the steps of: and (3) treating the xylitol ion-exchange liquid with mixed bed resin, collecting the mixed bed liquid, then carrying out vacuum concentration on the mixed bed liquid, and then sequentially crystallizing, centrifuging and drying the concentrated liquid to obtain crystalline xylitol.
Further, the method for raising and stabilizing the pH of crystalline xylitol comprises the following steps:
taking 2L of xylitol ion-exchange liquid, passing through 300ml of mixed bed resin, enabling the feeding flow of the xylitol ion-exchange liquid to be 20 ml/min-40 ml/min, processing for 50 min-100 min, collecting 1.5L of mixed bed liquid, then carrying out vacuum concentration on the mixed bed liquid to obtain concentrated liquid, crystallizing the concentrated liquid at 40-50 ℃ for 6-24 h, finally centrifuging and drying to obtain crystalline xylitol; wherein, the mixed bed resin is prepared by uniformly mixing 120ml of D101 type positive resin and 180ml of D201 type negative resin.
Further, refraction of the xylitol ionomer: 50-60%, pH: 4.0-5.0, conductivity: 5 us/cm-30 us/cm.
Further, the refraction of the mixed bed liquid is 45-55%, the pH value is 6.2-7.2, and the electric conductivity is 0.5-5.0 us/cm.
Further, the vacuum concentration conditions are that the vacuum degree is-0.085 MPa to-0.095 MPa, the temperature is 55 ℃ to 70 ℃, and the refraction of the obtained concentrated solution is 75% to 83%.
Further, the method for increasing and stabilizing the pH of crystalline xylitol further comprises a method for evaluating the pH stability of crystalline xylitol, the evaluation method comprising the steps of: dissolving crystalline xylitol to be evaluated by purified water to obtain a xylitol solution, measuring the pH value of the crystalline xylitol solution to be evaluated, storing the crystalline xylitol solution for one week, measuring the pH value of the xylitol solution again by the same method, comparing the pH values measured before and after twice, and judging that the pH value of the crystalline xylitol has stability if the difference between the two pH values is not more than 0.12, otherwise, judging that the crystalline xylitol has no stability.
Compared with the prior art, the method for improving and stabilizing the pH value of the crystal xylitol has the following characteristics:
1. after the mixed bed resin treatment, the pH value of 50% solution (w/w, the mass ratio of the xylitol crystal to purified water with the pH value of 5.80 is 1: 1) of the obtained finished product xylitol crystal is 6.00-6.58, while the pH value of 50% solution (w/w) of the finished product xylitol crystal which is not treated by the mixed bed resin is 5.65-5.90, and the product is relatively more stable and has more application range due to relatively higher pH value.
2. After mixed bed resin treatment, the pH value of a 50 percent solution is reduced by about 0.08 after the obtained finished product xylitol crystal is stored for one week; the finished product xylitol crystal which is not treated by the mixed bed is stored for a week, and the pH value of 50 percent solution is reduced by about 0.19. The crystal xylitol obtained after the mixed bed treatment is relatively more stable and is more suitable for being applied to formula products.
Detailed Description
In order to make the technical problems, technical solutions and advantageous effects to be solved by the present invention more apparent, the present invention is further described in detail below with reference to the following embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.
A preferred embodiment of the method of the present invention for raising and stabilizing the pH of crystalline xylitol comprises the steps of: and (3) treating the xylitol ion-exchange liquid with mixed bed resin, collecting the mixed bed liquid, then carrying out vacuum concentration on the mixed bed liquid, and then sequentially crystallizing, centrifuging and drying the concentrated liquid to obtain crystalline xylitol.
Specifically, the method for raising and stabilizing the pH of crystalline xylitol comprises the following steps:
taking 2L of xylitol ion-exchange liquid, passing through 300ml of mixed bed resin, enabling the feeding flow of the xylitol ion-exchange liquid to be 20 ml/min-40 ml/min, processing for 50 min-100 min, collecting 1.5L of mixed bed liquid, then carrying out vacuum concentration on the mixed bed liquid to obtain concentrated liquid, crystallizing the concentrated liquid at 40-50 ℃ for 6-24 h, finally centrifuging and drying to obtain crystalline xylitol; wherein, the mixed bed resin is prepared by uniformly mixing 120ml of D101 type positive resin and 180ml of D201 type negative resin.
Wherein the refraction of the xylitol ion-exchange liquid is as follows: 50-60%, pH: 4.0-5.0, conductivity: 5 us/cm-30 us/cm.
Wherein the refraction of the mixed bed liquid is 45-55%, the pH value is 6.2-7.2, and the conductance is 0.5-5.0 us/cm.
Wherein the vacuum concentration condition is that the vacuum degree is-0.085 MPa to-0.095 MPa, the temperature is 55 ℃ to 70 ℃, and the refraction of the obtained concentrated solution is 75% to 83%.
Moreover, the method for increasing and stabilizing the pH of crystalline xylitol further comprises a method for evaluating the pH stability of crystalline xylitol, the evaluation method comprising the steps of: dissolving crystalline xylitol to be evaluated by purified water to obtain a xylitol solution, measuring the pH value of the crystalline xylitol solution to be evaluated, storing the crystalline xylitol solution for one week, measuring the pH value of the xylitol solution again by the same method, comparing the pH values measured before and after twice, and judging that the pH value of the crystalline xylitol has stability if the difference between the two pH values is not more than 0.12, otherwise, judging that the crystalline xylitol has no stability.
The process of the present invention is further illustrated below with reference to specific examples.
Example 1
The first method for increasing and stabilizing the pH of crystalline xylitol comprises the following steps:
taking 2L of ion exchange liquid, refracting light: 55%, pH: 4.3, conductivity: 5us/cm, passing through 300ml of mixed bed resin, feeding flow rate of xylitol ion-exchange liquid is 25ml/min, time is 80min, collecting 1.5L of mixed bed liquid, refracting light is 51.5%, pH is 6.5, electric conductivity is 0.5us/cm, then vacuum concentrating is carried out until refraction is 77%, wherein vacuum degree is-0.095 MPa, temperature is 70 ℃, then concentrated liquid is crystallized at 40 ℃, crystallization time is 6h, finally, centrifugation and drying are carried out, and crystal xylitol is obtained.
The reaction solution was diluted with 20g, pH: 5.84 of purified water dissolved 20g of crystalline xylitol to give a 50% xylitol solution, the pH was found to be 6.48. After the crystalline xylitol solution was stored for one week, the pH of the xylitol solution was measured to be 6.40 by the same method. The difference between the pH values measured in the two previous and subsequent measurements was 0.08, and the pH of the crystalline xylitol prepared in example 1 was stable.
Example 2
The second method for increasing and stabilizing the pH of crystalline xylitol according to the present invention comprises the steps of:
taking 2L of ion exchange liquid, refracting light: 60%, pH: 5.0, conductivity: 15.0us/cm, passing through 300ml of mixed bed resin, feeding the xylitol ion-exchange liquid with the flow rate of 20ml/min for 100min, collecting 1.5L of mixed bed liquid, refracting light by 52.0%, having the pH value of 6.7 and the conductance of 2.0us/cm, then carrying out vacuum concentration to refract light by 83%, wherein the vacuum degree is-0.095 MPa, the temperature is 55 ℃, crystallizing the concentrated liquid at 45 ℃ for 24h, finally centrifuging and drying to obtain the crystal xylitol.
The reaction solution was diluted with 20g, pH: 5.84 of purified water dissolved 20g of crystalline xylitol to give a 50% xylitol solution, the pH was found to be 6.52. After the crystalline xylitol solution was stored for one week, the pH of the xylitol solution was measured to be 6.43 by the same method. The difference between the pH values measured before and after the measurement was 0.09, and the pH of the crystalline xylitol prepared in example 2 was stable.
Example 3
The third method for increasing and stabilizing the pH of crystalline xylitol according to the present invention comprises the steps of:
taking 2L of ion exchange liquid, refracting light: 50%, pH: 4.0, conductivity: 30.0 us/cm, passing through 300ml of mixed bed resin, feeding the xylitol ion-exchange liquid with the flow rate of 40ml/min for 50min, collecting 1.5L of mixed bed liquid, refracting the mixed bed liquid with the refraction of 45%, the pH value of 6.2 and the conductance of 5.0us/cm, then carrying out vacuum concentration to refract the mixed bed liquid with the refraction of 75%, wherein the vacuum degree is-0.085 MPa, the temperature is 65 ℃, then crystallizing the concentrated liquid at 50 ℃ for 16h, finally centrifuging and drying to obtain the crystal xylitol.
The reaction solution was diluted with 20g, pH: 5.84 of purified water dissolved 20g of crystalline xylitol to give a 50% xylitol solution, the pH was found to be 6.38. After the crystalline xylitol solution was stored for one week, the pH of the xylitol solution was measured to be 6.30 by the same method. The difference between the pH values measured in the two previous and subsequent measurements was 0.08, and the pH of the crystalline xylitol prepared in example 3 was stable.
Comparative example 1
Taking 2L of ion exchange liquid, refracting light: 55%, pH: 4.3, conductivity: 6.7us/cm, directly carrying out vacuum concentration until the refraction reaches 77%, wherein the vacuum degree is-0.095 MPa, and the temperature is 65 ℃. Then the concentrated solution is crystallized at 40 ℃ for 18 h. And finally, centrifuging and drying to obtain the crystal xylitol.
The reaction solution was diluted with 20g, pH: purified water of 5.84 dissolved 20g of crystalline xylitol to give a 50% xylitol solution, the pH was found to be 5.84. After the crystalline xylitol solution was stored for one week, the pH of the xylitol solution was measured to be 5.65 by the same method. The difference between the pH values measured in the previous and subsequent steps was 0.19, and the pH of the crystalline xylitol prepared in comparative example 1 was not stable.
Comparative example 2
Taking 2L of ion exchange liquid, refracting light: 56%, pH: 4.5, conductivity: 15.0us/cm, directly carrying out vacuum concentration until the refraction reaches 80%, wherein the vacuum degree is-0.095 MPa, and the temperature is 65 ℃. Then the concentrated solution is crystallized at 40 ℃ for 15 h. And finally, centrifuging and drying to obtain the crystal xylitol.
The reaction solution was diluted with 20g, pH: 5.84 of purified water dissolved 20g of crystalline xylitol to give a 50% xylitol solution, the pH was found to be 5.90. After the crystalline xylitol solution was stored for one week, the pH of the xylitol solution was measured to be 5.71 by the same method. The difference between the pH values measured in the previous and subsequent steps was 0.19, and the pH of the crystalline xylitol prepared in comparative example 2 was not stable.
The test data for the above examples and comparative examples are statistically summarized to give the following table:
| xylitol solution experimental sample | pH 1 st measurement | pH 2 (after one week) assay | Difference between them | Determination (≦ 0.12) |
| Example 1 | 6.48 | 6.40 | 0.08 | Has the stability |
| Example 2 | 6.52 | 6.43 | 0.09 | Has the stability |
| Example 3 | 6.38 | 6.30 | 0.08 | Has the stability |
| Comparative example 1 | 5.84 | 5.65 | 0.19 | Do not have stability |
| Comparative example 2 | 5.90 | 5.71 | 0.19 | Do not have stability |
Therefore, the pH of the crystalline xylitol prepared using the method for increasing and stabilizing the pH of the crystalline xylitol of the present invention has stability, achieving the technical objects of the present invention.
The above description is only for the purpose of illustrating the preferred embodiments of the present invention and is not to be construed as limiting the invention, and any modifications, equivalents and improvements made within the spirit and principle of the present invention are intended to be included within the scope of the present invention.
Claims (7)
1. A method for increasing and stabilizing the pH of crystalline xylitol comprising the steps of: treating the xylitol ion-exchange liquid with mixed bed resin, collecting the mixed bed liquid, then carrying out vacuum concentration on the mixed bed liquid, and sequentially crystallizing, centrifuging and drying the concentrated liquid to obtain crystalline xylitol; the method for increasing and stabilizing the pH of crystalline xylitol comprises the following steps:
taking 2L of xylitol ion-exchange liquid, passing through 300ml of mixed bed resin, enabling the feeding flow of the xylitol ion-exchange liquid to be 20 ml/min-40 ml/min, processing for 50 min-100 min, collecting 1.5L of mixed bed liquid, then carrying out vacuum concentration on the mixed bed liquid to obtain concentrated liquid, crystallizing the concentrated liquid at 40-50 ℃ for 6-24 h, finally centrifuging and drying to obtain crystalline xylitol; wherein, the mixed bed resin is prepared by uniformly mixing 120ml of D101 type positive resin and 180ml of D201 type negative resin;
refraction of the xylitol ion-exchange liquid: 50-60%, pH: 4.0-5.0, conductivity: 5 us/cm-30 us/cm.
2. The method for increasing and stabilizing the pH of crystalline xylitol according to claim 1, wherein the mixed bed liquid has a refractive index of 45-55%, a pH of 6.2-7.2 and an electrical conductance of 0.5-5.0 us/cm.
3. The method for increasing and stabilizing the pH of crystalline xylitol according to claim 2, wherein the vacuum concentration is carried out under conditions of a vacuum degree of-0.085 MPa to-0.095 MPa, a temperature of 55 ℃ to 70 ℃, and a refractive index of the obtained concentrated solution is 75% to 83%.
4. The method for increasing and stabilizing the pH of crystalline xylitol according to claim 3, wherein said method for increasing and stabilizing the pH of crystalline xylitol comprises the steps of:
taking 2L of ion exchange liquid, refracting light: 55%, pH: 4.3, conductivity: 5us/cm, passing through 300ml of mixed bed resin, feeding flow rate of xylitol ion-exchange liquid is 25ml/min, time is 80min, collecting 1.5L of mixed bed liquid, refracting 60%, pH is 7.2, conductance is 0.5us/cm, then vacuum concentrating to refractivity 77%, wherein vacuum degree is-0.095 MPa, temperature is 70 ℃, crystallizing the concentrated solution at 40 ℃, crystallizing time is 6h, finally centrifuging, drying, and obtaining crystal xylitol.
5. The method for increasing and stabilizing the pH of crystalline xylitol according to claim 3, wherein said method for increasing and stabilizing the pH of crystalline xylitol comprises the steps of:
taking 2L of ion exchange liquid, refracting light: 60%, pH: 5.0, conductivity: 15.0us/cm, passing through 300ml of mixed bed resin, feeding the xylitol ion-exchange liquid with the flow rate of 20ml/min for 100min, collecting 1.5L of mixed bed liquid, refracting light by 52.0%, having the pH value of 6.7 and the conductance of 2.0us/cm, then carrying out vacuum concentration to refract light by 83%, wherein the vacuum degree is-0.095 MPa, the temperature is 55 ℃, crystallizing the concentrated liquid at 45 ℃ for 24h, finally centrifuging and drying to obtain the crystal xylitol.
6. The method for increasing and stabilizing the pH of crystalline xylitol according to claim 3, wherein said method for increasing and stabilizing the pH of crystalline xylitol comprises the steps of:
taking 2L of ion exchange liquid, refracting light: 50%, pH: 4.0, conductivity: 30us/cm, passing through 300ml of mixed bed resin, feeding flow rate of xylitol ion-exchange liquid is 40ml/min, time is 50min, collecting 1.5L of mixed bed liquid, refracting 45%, pH is 6.2, conductance is 5.0us/cm, then vacuum concentration is carried out until refraction is 75%, wherein vacuum degree is-0.085 MPa, temperature is 65 ℃, crystallization is carried out on the concentrated liquid at 50 ℃, crystallization time is 16h, finally centrifugation and drying are carried out, and crystal xylitol is obtained.
7. The method for increasing and stabilizing the pH of crystalline xylitol according to any one of claims 1 to 6, wherein said method for increasing and stabilizing the pH of crystalline xylitol further comprises a method for evaluating the pH stability of crystalline xylitol, which comprises the steps of: dissolving crystalline xylitol to be evaluated by purified water to obtain a xylitol solution, measuring the pH value of the crystalline xylitol solution to be evaluated, storing the crystalline xylitol solution for one week, measuring the pH value of the xylitol solution again by the same method, comparing the pH values measured before and after twice, and judging that the pH value of the crystalline xylitol has stability if the difference between the two pH values is not more than 0.12, otherwise, judging that the crystalline xylitol has no stability.
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| CN110894180B (en) * | 2019-12-12 | 2022-07-26 | 浙江华康药业股份有限公司 | Method for producing high-pH crystal xylitol by using strong base resin |
| CN112442556A (en) * | 2020-12-07 | 2021-03-05 | 浙江华康药业股份有限公司 | Method for reducing sugar in xylitol crystal |
| CN112661796A (en) * | 2020-12-29 | 2021-04-16 | 浙江华康药业股份有限公司 | Method for improving pH and stability of crystal xylitol |
| CN115888165A (en) | 2022-12-09 | 2023-04-04 | 浙江华康药业股份有限公司 | System and method for preparing high-quality xylitol crystals |
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| CN101863737A (en) * | 2010-07-01 | 2010-10-20 | 安徽丰原发酵技术工程研究有限公司 | Method for refining xylitol fermentation liquor |
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| CN101863737A (en) * | 2010-07-01 | 2010-10-20 | 安徽丰原发酵技术工程研究有限公司 | Method for refining xylitol fermentation liquor |
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