Spherical sialic acid particles and methods of making same

Abstract

The application discloses a kind of spherical sialic acid particles and preparation method thereof, and the sialic acid particle sialic acid rest angle ≤35 °, content ≥98.5%, bulk density ≥0.55g / mL, moisture content ≤0.3%.Preparation method is first to remove impurity after sialic acid-containing fermentation liquor is decolorized and concentrated to sialic acid content 400-600g / L feed liquid, then the sialic acid concentrated solution obtained is pumped into anti-solvent stirring crystallization, and spherical sialic acid particles are obtained after solid-liquid separation and drying.The sialic acid crystal prepared in the application has better fluidity than general sialic acid crystal because of the morphology and particle size characteristics of spherical particles, has obvious advantages in the anti-caking property of product, and has higher bulk density and compressibility, and the preparation process is simple.

Description

Technical Field

[0001] This invention relates to the field of food chemical technology, and more specifically to a spherical sialic acid particle and its preparation method. Background Technology

[0002] Sialic acid, also known as neuraminic acid and N-acetylneuraminic acid, is an acylated derivative of a 9-carbon monosaccharide. Currently, sialic acid is mainly produced through enzymatic conversion, microbial fermentation, and natural product extraction. The sialic acid obtained through these methods is then purified, crystallized, and dried to produce sialic acid crystals.

[0003] Currently, through continuous optimization of purification processes, the content of sialic acid products has been significantly improved. However, the obtained sialic acid granules generally have low bulk density, which easily leads to the dispersion of crystal powder during use. During mixing, the powder easily adheres to the walls of the mixing container, causing many difficulties for downstream applications in solid mixtures, tablets, and other dosage forms. Patent CN113416222A discloses sialic acid granules and its preparation method, including crystallizing sialic acid extract to obtain crude sialic acid crystals, performing a first and second washing step on the crude sialic acid crystals using a washing solution, and then granulating. This process is cumbersome, involves many pieces of equipment, and requires complex processing steps such as acid adjustment, cooling crystallization, first washing, centrifugation, second washing, cooling centrifugation, extrusion granulation, drying, pulverization, and sieving. Authorized patent CN111087432B discloses a method for separating and extracting N-acetylneuraminic acid, first obtaining a concentrated sialic acid solution, then adjusting the pH and adding a reverse solvent to precipitate crystals, followed by centrifugation, washing, and drying. While the entire separation process is simple to operate, the resulting crystals have poor performance.

[0004] Therefore, how to provide a simple and effective method for preparing saliva that improves the physicochemical properties of the product is a problem that urgently needs to be solved by those skilled in the art. Summary of the Invention

[0005] In view of this, the present invention provides sialic acid spherical particles with high fluidity, high anti-caking properties, high crystal bulk density and low water content, and provides a corresponding preparation method.

[0006] To achieve the above objectives, the present invention adopts the following technical solution:

[0007] First, this invention provides a method for preparing spherical sialic acid particles, comprising the following steps:

[0008] (1) The fermentation broth containing sialic acid is sequentially filtered through a ceramic membrane, heated, decolorized with activated carbon, filtered through a plate and frame filter, ultrafiltered, and nanofiltered, and then vacuum concentrated to a sialic acid content of 400-600 g / L.

[0009] (2) The sialic acid concentrate obtained in step (1) is added to the antisolvent at a certain speed while stirring. After the addition is completed, stirring is continued until the crystallization is completed. The solid-liquid separation of the liquid containing suspended crystals is obtained to obtain crystals. After vacuum drying, spherical sialic acid particles are obtained.

[0010] The sialic acid concentrate of this invention has a concentration of 400-600 g / L. Sialic acid has a high viscosity. When sialic acid is dropped into an antisolvent (low density and low viscosity) stirred at a certain speed, the sialic acid will shrink and form spherical droplets due to interfacial tension. When the antisolvent penetrates into the sialic acid droplets (the sialic acid droplets contain 40-60% water), the water in the sialic acid diffuses into the antisolvent, causing the sialic acid in the sialic acid droplets to precipitate and form spherical crystals. When the sialic acid concentration is ≤400 g / L, the sialic acid viscosity is low, and it is difficult to form spherical droplets when dropped into the antisolvent.

[0011] Preferably, the ceramic membrane filtration in step (1) uses a ceramic membrane of 50-500nm, which can effectively filter and remove bacteria and insoluble impurities in the fermentation broth.

[0012] Preferably, the heating temperature in step (1) is 80-100℃ and the holding time is 0.5-1h.

[0013] Preferably, the activated carbon decolorization and plate and frame filtration in step (1) are as follows: after the liquid is cooled to 40-70°C, 2-10% of the liquid mass of activated carbon is added for decolorization for 0.5-2 hours, and the activated carbon is removed by plate and frame filtration to obtain the decolorized liquid.

[0014] Preferably, the ultrafiltration in step (1) uses a 3000-8000 Da filter membrane; the nanofiltration uses a 300-800 Da filter membrane, and the retentate is concentrated under vacuum at 60°C after nanofiltration.

[0015] Preferably, the antisolvent in step (2) is acetone, isopropanol or ethanol, the temperature of the antisolvent is controlled at 5-20°C, more preferably 10-15°C, and the volume of the antisolvent is 3-10 times the total volume of the concentrate, more preferably 5-7 times.

[0016] Isopropanol, acetone, and ethanol, among other antisolvents, are miscible with water and can rapidly penetrate into spherical droplets of sialic acid. Simultaneously, water diffuses into the antisolvent, reducing the water content within the spherical droplets and causing sialic acid to saturate and precipitate as spherical crystals. If sialic acid is added to other water-insoluble organic solvents (such as ethyl acetate, benzene, or n-hexane), the organic solvent cannot rapidly penetrate the droplets to form spherical crystals, and the droplets may agglomerate.

[0017] Preferably, the addition in step (2) is done by pumping or dripping at a rate of 5-20 mL / min, more preferably 10-15 mL / min.

[0018] Preferably, the stirring speed in step (2) is 300-600 r / min, more preferably 350-450 r / min; the continuous stirring time is 4-12 h, more preferably 8-10 h.

[0019] Too low a stirring speed will cause sialic acid droplets or particles to settle at the bottom (potentially causing them to stick together), which is detrimental to crystal growth. A certain amount of stirring can create friction on spherical particles, smoothing the crystal surface. However, excessive stirring speed can cause the crystals to collide and break.

[0020] In addition, the present invention also provides spherical sialic acid particles prepared by the method described in the above technical solution.

[0021] Furthermore, the sialic acid particles have a sialic acid repose angle ≤35°, a content ≥98.5%, a bulk density ≥0.55g / mL, and a moisture content ≤0.3%.

[0022] As can be seen from the above technical solution, compared with the prior art, the present invention has the following beneficial effects:

[0023] This invention provides spherical sialic acid particles and their preparation method. The spherical particles have better flowability than ordinary sialic acid crystals due to their morphology and particle size characteristics, resulting in significant advantages in the anti-caking properties of the product. They also have higher bulk density and compressibility, and the preparation process is simple. Attached Figure Description

[0024] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the provided drawings without creative effort.

[0025] Figure 1 This is a crystallization diagram of the spherical sialic acid particles prepared in Example 1 of the present invention;

[0026] Figure 2 This is a crystallographic diagram of common sialic acid. Detailed Implementation

[0027] The technical solution of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0028] Example 1

[0029] The fermentation broth containing sialic acid was filtered through a 100nm ceramic membrane to remove the bacteria and insoluble impurities. The filtered broth was then heated to 90℃ and maintained for 30 minutes. After cooling to 60℃, 6% of the weight of activated carbon was added for decolorization for 0.5 hours. The activated carbon was then removed by a plate and frame filter press to obtain the decolorized filtrate.

[0030] The decolorized filtrate was filtered through a 5000 Da filter membrane, and the resulting filtrate was filtered through a 300 Da nanofiltration membrane. The retentate was collected, and then the retentate was concentrated under vacuum at 60°C to a sialic acid concentrate with a sialic acid content of 500 g / L.

[0031] Sialic acid concentrate was pumped into 5 times its volume of 10℃ acetone at a rate of 10 mL / min. At the same time, the acetone solution of sialic acid concentrate was pumped in at a speed of 400 r / min. After crystallization and stirring for 8 hours, the resulting liquid containing suspended crystals was filtered to obtain wet crystals.

[0032] The filtered wet crystals were dried under vacuum at 60°C for 4 hours to obtain spherical crystal particles.

[0033] The obtained sialic acid spherical crystal particles had a repose angle of 32°, a bulk density of 0.6 g / mL, a purity of 99.3%, and a moisture content of 0.3%.

[0034] Example 2

[0035] The fermentation broth containing sialic acid was filtered through a 500nm ceramic membrane to remove the bacteria and insoluble impurities. The filtered broth was then heated to 80℃ and maintained for 50 minutes. After cooling to 60℃, 8% of the weight of the broth was added to the activated carbon for decolorization for 1 hour. The activated carbon was then removed by a plate and frame filter press to obtain the decolorized filtrate.

[0036] The decolorized filtrate was filtered through a 6000Da filter membrane, and the resulting filtrate was filtered through a 500Da nanofiltration membrane. The retentate was collected, and then the retentate was concentrated under vacuum at 60°C to a sialic acid concentrate with a sialic acid content of 550 g / L.

[0037] Sialic acid concentrate was pumped into 8 times its volume of 10℃ acetone at a rate of 15 mL / min. At the same time, the acetone solution of sialic acid concentrate was pumped in at a speed of 400 r / min. After crystallization and stirring for 10 h, the resulting liquid containing suspended crystals was filtered to obtain wet crystals.

[0038] The filtered wet crystals were dried under vacuum at 55°C for 5 hours to obtain spherical crystal particles.

[0039] The obtained sialic acid spherical crystal particles had a repose angle of 33°, a bulk density of 0.6 g / mL, a purity of 99.5%, and a moisture content of 0.28%.

[0040] Example 3

[0041] The fermentation broth containing sialic acid was filtered through a 200nm ceramic membrane to remove the bacteria and insoluble impurities. The filtered broth was then heated to 85℃ and maintained for 50 minutes. After cooling to 55℃, 10% of the weight of the broth was added to the activated carbon for decolorization for 1 hour. The activated carbon was then removed by a plate and frame filter press to obtain the decolorized filtrate.

[0042] The decolorized filtrate was filtered through a 5000 Da filter membrane, and the resulting filtrate was filtered through a 600 Da nanofiltration membrane. The retentate was collected, and then the retentate was concentrated under vacuum at 60°C to a sialic acid concentrate with a sialic acid content of 600 g / L.

[0043] Sialic acid concentrate was pumped into 10 times its volume of 10℃ acetone at a rate of 15 mL / min. At the same time, the acetone solution of sialic acid concentrate was pumped in at a speed of 450 r / min. After crystallization and stirring for 10 h, the resulting liquid containing suspended crystals was filtered to obtain wet crystals.

[0044] The filtered wet crystals were dried under vacuum at 55°C for 5 hours to obtain spherical crystal particles.

[0045] The obtained sialic acid spherical crystal particles had a repose angle of 31°, a bulk density of 0.62 g / mL, a purity of 99.4%, and a moisture content of 0.29%.

[0046] The morphology of the spherical sialic acid crystals prepared in Example 1 is shown in the attached figure. Figure 1 As shown, Figure 1 The prepared product crystals are spherical in shape. Figure 2 It is ordinary sialic acid crystals. Figure 2 This indicates that ordinary sialic acid crystals are small, clustered, and have an uneven particle size distribution.

[0047] Sialic acid spherical crystals, due to their smooth particle surface and small contact angle, are better able to reduce capillary hygroscopic absorption in air. Spherical potassium chloride of the same particle size exhibits higher anti-caking properties than cubic potassium chloride, fully demonstrating the advantage of spherical morphology in improving particle anti-caking properties.

[0048] Anti-caking experiments were conducted using the product prepared in Example 1 and other crystalline forms of sialic acid crystals. Sialic acid crystals of the same particle size but different crystalline forms were placed in plastic bags and placed in an accelerated chamber at 37°C and 75% humidity. The number of days it took for caking to occur was observed. The results are shown in Tables 1-2 below.

[0049] Table 1 Comparison Data

[0050] Bag Number plate-like crystals needle-like crystals Square crystal Spherical crystals 1 20 days 25 days 31 days 47 days 2 22 days 26 days 29 days 48 days 3 21 days 24 days 32 days 46 days 4 23 days 27 days 30 days 49 days

[0051] Table 2. Angle of repose for sialic acids with the same crystal size but different crystal morphologies (a smaller angle of repose indicates better fluidity).

[0052]

[0053]

[0054] The above results show that the spherical crystals prepared by the method of the present invention have better flowability and anti-slab junction effect.

[0055] The various embodiments in this specification are described in a progressive manner, with each embodiment focusing on the differences from other embodiments. The same or similar parts between the various embodiments can be referred to each other.

[0056] The above description of the disclosed embodiments enables those skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for preparing sialic acid particles in a spherical shape, characterized by, The method comprises the following steps: (1) sequentially filtering, heating, decolorizing with activated carbon, plate and frame filtering, ultrafiltration, nanofiltration, and vacuum concentration of the fermentation liquid containing sialic acid to obtain a feed liquid with a sialic acid content of 400-600 g / L; (2) adding the sialic acid concentrated liquid obtained in step (1) into acetone at a certain speed, wherein the volume of the acetone is 3-10 times the total volume of the concentrated liquid, stirring while adding, continuing to stir until crystallization is completed after the addition is completed, the stirring speed is 300-600 r / min, solid-liquid separation is performed on the feed liquid containing suspended crystals to obtain crystals, and spherical sialic acid particles are obtained after vacuum drying.

2. The method of claim 1, wherein the sialic acid particles are spherical. In step (1), ceramic membrane filtration is performed using a ceramic membrane with a pore size of 50-500 nm.

3. The method of claim 1, wherein the sialic acid particles are spherical. In step (1), the heating temperature is 80-100℃, and the holding time is 0.5-1 h.

4. The method of claim 1, wherein the sialic acid particles are spherical. In step (1), the decolorization with activated carbon and plate and frame filtering are specifically as follows: after the feed liquid is cooled to 40-70℃, 2-10% activated carbon by mass of the feed liquid is added for 0.5-2 h of decolorization, and plate and frame filtering is performed to remove the activated carbon to obtain a decolorized liquid.

5. The method of claim 1, wherein the sialic acid particles are spherical. In step (1), the ultrafiltration is performed using a filter membrane with a molecular weight cut-off of 3000-8000 Da, and the nanofiltration is performed using a filter membrane with a molecular weight cut-off of 300-800 Da; the retentate is obtained after nanofiltration and vacuum concentration at 60℃.

6. The method of claim 1, wherein the sialic acid particles are spherical. The temperature of the anti-solvent is controlled at 5-20℃.

7. The method of claim 1, wherein the sialic acid particles are spherical. In step (2), the addition is performed in the form of pumping or dripping, and the speed is 5-20 mL / min.

8. The method of claim 1, wherein the sialic acid particles are spherical. The continuous stirring time is 4-12 h.

9. The method of claim 1, wherein the sialic acid particles are spherical. The sialic acid particles have a sialic acid rest angle of ≤35°, a content of ≥98.5%, a bulk density of ≥0.55 g / mL, and a moisture content of ≤0.3%.

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