阅读说明：本技术 一种提高姜黄素晶体堆密度和流动性的方法 (Method for improving bulk density and fluidity of curcumin crystal ) 是由 龚俊波 万旭兴 曹越超 吴送姑 张韶男 刘剑 侯宝红 于 2021-08-31 设计创作，主要内容包括：本发明提供了一种提高姜黄素晶体堆密度和流动性的方法,所述方法包括如下步骤：将姜黄素的1,4-二氧六环溶液进行一次降温至析出晶体,其次进行升温,并进行一次养晶,而后进行二次降温,并进行二次养晶,得到姜黄素晶体；通过该方法得到的姜黄素产品晶习呈棒状,流动性较好,产品堆密度达到0.5g/mL以上,产品纯度达到99％以上。(The invention provides a method for improving the bulk density and the flowability of curcumin crystals, which comprises the following steps: carrying out primary cooling on a 1, 4-dioxane solution of curcumin until crystals are separated out, then carrying out heating, carrying out primary crystal growing, then carrying out secondary cooling, and carrying out secondary crystal growing to obtain curcumin crystals; the curcumin product obtained by the method is rod-shaped in crystal habit and good in fluidity, the bulk density of the product reaches more than 0.5g/mL, and the purity of the product reaches more than 99%.)

1. A method for improving the bulk density and the flowability of curcumin crystals, which is characterized by comprising the following steps:

and (3) carrying out primary cooling on the 1, 4-dioxane solution of the curcumin until crystals are separated out, then carrying out heating, carrying out primary crystal growing, then carrying out secondary cooling, and carrying out secondary crystal growing to obtain the curcumin crystals.

2. The method as claimed in claim 1, wherein the concentration of the 1, 4-dioxane solution of curcumin is 0.091-0.20 g/mL;

preferably, the 1, 4-dioxane solution of curcumin is obtained by dissolving curcumin in 1, 4-dioxane at 50-75 deg.C.

3. The method according to claim 1, wherein the cooling rate of the primary cooling is 0.5-6 ℃/h, preferably 1 ℃/h.

4. The method according to claim 1, wherein the temperature of the elevated temperature is 2-10 ℃ higher than the temperature of the primary temperature reduction;

preferably, the time for primary crystal growth is 0.5-2.0 h.

5. The method according to claim 1, wherein the temperature of the secondary cooling is 45-65 ℃;

preferably, the time of the secondary crystal growth is 0.5-2.0 h.

6. The method according to claim 1, wherein the preparation method further comprises sequentially performing solid-liquid separation and drying on the mixture obtained after the secondary crystal growth;

preferably, the solid-liquid separation mode is filtration;

preferably, the drying is carried out under vacuum, the drying temperature is 50-80 ℃, and the drying time is 8-24 h.

7. Method according to claim 1, characterized in that it comprises the following steps:

(1) placing curcumin in 1, 4-dioxane, and dissolving at 50-75 deg.C to obtain 1, 4-dioxane solution of curcumin;

(2) cooling the 1, 4-dioxane solution of curcumin obtained in the step (1) at a cooling rate of 0.5-6.0 ℃/h for one time until crystals are separated out, then heating to 2-10 ℃, growing the crystals for 0.5-2.0h, then cooling to 45-65 ℃, growing the crystals for 0.5-2.0h, and obtaining a mixture;

(3) filtering the mixture obtained in the step (2), and drying at 50-80 ℃ for 8-24h under vacuum condition to obtain curcumin crystals.

8. Curcumin crystals prepared by the method according to any one of claims 1 to 7.

9. A curcumin crystal according to claim 8 wherein the bulk density of said curcumin crystal is 0.5g/mL or more;

preferably, the angle of repose of the curcumin crystals is 40 ° or less;

preferably, the crystal habit of the curcumin crystal is a rod shape, and the crystal form is a crystal form I;

preferably, the purity of the curcumin crystals is 99% or more;

preferably, the solvent residue of the curcumin crystals is 50ppm or less.

10. Use of curcumin crystals according to claim 8 in food additives.

Technical Field

The invention belongs to the technical field of medical crystallization, and relates to a method for improving the bulk density and the flowability of curcumin.

Background

Curcumin (curculin) was originally a natural hydrophobic polyphenol compound extracted from turmeric rhizome in 1870. It exists as keto-enol tautomers which are chemically named (E, E) -1, 7-bis (4-hydroxy-3-methoxyphenyl) -1, 6-heptadiene-3, 5-dione and (E, E) -1, 7-bis (4-hydroxy-3-methoxyphenyl) -1, 6-heptadiene-3-keto-5-enol, respectively.

Curcumin is orange yellow crystal powder and has long been used as a natural pigment for food dyeing and food additives. With the continuous and intensive research, curcumin can be used as an acid-base indicator (pH 7.8 (yellow) -9.2 (reddish brown)), and has obvious inhibition and prevention effects on diseases such as cancer, senile dementia and inflammation. In addition, curcumin can be used as antiseptic, cosmetic, stomachic, analgesic, diuretic, choleretic, immunostimulant, skin mutation induced by ultraviolet light, blood glucose lowering, and nematocidal.

In the prior art, there are many methods for separating and purifying curcumin, such as the step of ethanol reflux recrystallization after obtaining crude curcumin by using a ginger crushing and extracting process in CN 104072352A. CN107805193A discloses a production method for preparing low-residue soluble curcumin crystals, which is obtained by adding additives, refining agents and other reagents, and takes about 12 hours, but the process uses a large amount of organic solvents and surfactants, which not only increases the cost, but also has the risk of introducing new impurities. CN102617316A discloses a method for extracting curcumin from turmeric, which comprises extracting curcumin with organic solvent, separating to remove heavy metals to obtain precipitate, mixing the precipitate with aqueous polar solvent, heating, stirring, naturally cooling to room temperature, and filtering to obtain curcumin crystal. Patent CN107353190A mentions that curcumin precipitate is obtained by drying, grinding, steaming, mixing with ethanol for dissolution, filtering and distilling after purification.

CN110771892A mentions that curcumin extract is used as a raw material, a certain proportion of crystallizing agent is added, reflux cooling crystallization is carried out after high-temperature dissolution, heat preservation is carried out, high-quality curcumin is obtained after drying, the time cost in the high-quality curcumin is counted, and the total time cost needs more than 50 hours even if the time required by cooling crystallization is not calculated.

Curcumin can be directly filled into capsules as a raw material for dietary supplements or pharmaceutical preparations, the requirements on the fluidity and the bulk density of the curcumin are higher in the filling or tabletting process, the bulk density of a product obtained by the existing curcumin production process is about 0.4g/mL, and the angle of repose is more than 40 degrees, which seriously influences the application of the curcumin in the fields of pharmaceutical preparations and the like.

In view of the above, the application of curcumin in the fields of medicine, food and the like is widened, and the application problem of curcumin at present is overcome. Therefore, there is a need to develop a high quality curcumin product with high bulk density and good fluidity.

Disclosure of Invention

The invention aims to provide a method for improving the bulk density and the fluidity of curcumin, and by utilizing the method, the obtained curcumin product is rod-shaped in crystal habit and good in fluidity, the bulk density of the product reaches more than 0.5g/mL, and the purity of the product reaches more than 99%.

In order to achieve the purpose, the invention adopts the following technical scheme:

the invention aims to provide a method for improving the bulk density and the fluidity of curcumin, which comprises the steps of carrying out primary cooling on a 1, 4-dioxane solution of curcumin to separate out crystals, then carrying out primary crystal growing, then carrying out secondary cooling, and carrying out secondary crystal growing to obtain curcumin crystals.

The invention utilizes the Ostwald curing rule and adopts the operation of temperature return, thereby accelerating the dissolution of a large amount of small particles in the primary cooling process, and simultaneously, the secondary cooling can further grow the crystals with larger granularity, and finally the product with uniform granularity, larger bulk density and better fluidity is obtained.

The concentration of the 1, 4-dioxane solution of curcumin is 0.091-0.20g/mL, such as 0.091g/mL, 0.1g/mL, 0.11g/mL, 0.12g/mL, 0.13g/mL, 0.14g/mL, 0.15g/mL, 0.16g/mL, 0.17g/mL, 0.18g/mL, 0.19g/mL, 0.20g/mL and the like.

Preferably, the 1, 4-dioxane solution of curcumin is obtained by dissolving curcumin in 1, 4-dioxane at 50-75 deg.C.

Preferably, the cooling rate of the primary cooling is 0.5-6 ℃/h, such as 0.5 ℃/h, 1 ℃/h, 1.5 ℃/h, 2 ℃/h, 2.5 ℃/h, 3 ℃/h, 3.5 ℃/h, 4 ℃/h, 4.5 ℃/h, 5 ℃/h, 5.5 ℃/h, 6 ℃/h, and the like, preferably 1 ℃/h.

In the present invention, if the temperature reduction rate is too high, the obtained crystal particle size is small, and the bulk density is as low as 0.5g/mL or less.

Preferably, the temperature of the temperature rise is 2 to 10 ℃ higher than the temperature of the primary temperature decrease, such as 2 ℃, 3 ℃,4 ℃,5 ℃,6 ℃,7 ℃, 8 ℃, 9 ℃, 10 ℃ and the like.

Preferably, the time for the primary crystal growth is 0.5-2.0h, such as 0.5h, 0.8h, 1h, 1.2h, 1.5h, 1.8h, 2.0h and the like.

In the invention, if the temperature is raised to a lower degree, the small particles cannot be completely dissolved; if the temperature is increased too much, the precipitated crystals may be completely dissolved, and finally, the product may have uneven particle size and reduced bulk density. The crystal growing can activate crystal faces and accord with Ostwald curing rules.

Preferably, the temperature of the secondary cooling is 45-65 ℃, such as 45 ℃, 48 ℃, 50 ℃, 52 ℃, 55 ℃, 58 ℃, 60 ℃, 62 ℃, 65 ℃ and the like.

Preferably, the time for the secondary crystal growth is 0.5-2.0h, such as 0.5h, 0.8h, 1h, 1.2h, 1.5h, 1.8h, 2.0h and the like.

In the invention, when the temperature is reduced to below 45 ℃, the growth rate of the crystal is too low, so that the probability of secondary nucleation of the system is greatly increased, and the particle size distribution of the product is uneven. The crystal growth can ensure that the consumption of supersaturation is more complete, the yield of the product is more stable, and the Ostwald ripening rule is also met.

Preferably, the preparation method further comprises the step of sequentially carrying out solid-liquid separation and drying on the mixture obtained after the secondary crystal growth.

Preferably, the solid-liquid separation mode is filtration.

Preferably, the drying is performed under vacuum conditions at a temperature of 50-80 ℃, e.g., 50 ℃, 55 ℃, 60 ℃, 65 ℃, 70 ℃, 75 ℃, 80 ℃ and the like, for a time of 8-24h, e.g., 8h, 10h, 12h, 14h, 16h, 18h, 20h, 22h, 24h and the like.

As a preferred technical scheme of the invention, the method comprises the following steps:

(1) placing curcumin in 1, 4-dioxane, and dissolving at 50-75 deg.C to obtain 1, 4-dioxane solution of curcumin;

(2) cooling the 1, 4-dioxane solution of curcumin obtained in the step (1) at a cooling rate of 0.5-6 ℃/h for one time until crystals are separated out, then heating to 2-10 ℃, growing crystals for 0.5-2.0h, then cooling to 45-65 ℃, growing crystals for 0.5-2.0h, and obtaining a mixture;

(3) filtering the mixture obtained in the step (2), and drying at 50-80 ℃ for 8-24h under vacuum condition to obtain curcumin crystals.

The second purpose of the invention is to provide curcumin crystals prepared by the method in the first purpose.

Preferably, the bulk density of the curcumin crystals is 0.5g/mL or more.

Preferably, the angle of repose of the curcumin crystals is 40 ° or less.

Preferably, the crystal habit of the curcumin crystal is a rod shape, and the crystal form is a crystal form I.

Preferably, the purity of the curcumin crystals is 99% or more.

Preferably, the solvent residue of the curcumin crystals is 50ppm or less.

The third purpose of the invention is to provide the application of the curcumin crystal in food additives.

Compared with the prior art, the invention has the following beneficial effects:

the curcumin product prepared by the method provided by the invention is rod-shaped in crystal habit and good in fluidity, the bulk density of the product reaches more than 0.5g/mL, and the purity of the product reaches more than 99%.

Drawings

Fig. 1 is an SEM image of 1, 4-dioxane solvate of curcumin prepared in example 1;

fig. 2 is an SEM image of curcumin product prepared in example 1;

FIG. 3 is SEM image of crude curcumin powder;

FIG. 4 is a PXRD spectrum of curcumin prepared in the example;

FIG. 5 is a TG plot of curcumin prepared in the examples;

figure 6 DSC profile of curcumin prepared in example.

Detailed Description

The technical solution of the present invention is further explained by the following embodiments. It should be understood by those skilled in the art that the examples are only for the understanding of the present invention and should not be construed as the specific limitations of the present invention.

Example 1

Weighing 11g of curcumin crude powder raw material, dissolving in 100g of 1, 4-dioxane at 55 ℃ with stirring, cooling to 41 ℃ at a cooling rate of 1 ℃/h, then heating to 48 ℃, and growing crystals for 2 h; cooling and returning to the temperature, and finally maintaining the temperature at 43 ℃ for crystal growth for 2 hours; filtering, then desolventizing at 60 ℃ by using a vacuum drying oven for 12 hours, and characterizing after the desolventizing is completed.

Fig. 1 is a scanning electron micrograph of 1, 4-dioxane solvate of curcumin obtained in example 1 (model TM3000, Hitachi, Japan), and it can be seen from fig. 1 that the crystal habit of the product is a rod.

Fig. 2 is a scanning electron micrograph (model TM3000, Hitachi, Japan) of the curcumin product after solvent removal obtained in example 1, and it can be seen from fig. 2 that the crystal habit of the product is a rod.

FIG. 3 is a scanning electron micrograph of crude curcumin powder (model TM3000, Hitachi, Japan), and the particle size of crude curcumin is smaller as can be seen by comparing FIG. 2 with FIG. 3.

FIG. 4 is the XRD pattern (model D/MAX-2500, Japan) of the product obtained in example 1, and it can be seen from FIG. 4 that the product is a stable 1 crystal form of commercially available curcumin.

FIG. 5 is a TG diagram (model number Mettler Toledo, TGA/DSC1/SF) of the product obtained in example 1, from which FIG. 5 it can be seen that the organic solvent contained in the solvate has been removed.

FIG. 6 shows the DSC of the product obtained in example 1 (model Mettler-Toledo, DSC1/500, Switzerland), from FIG. 6 it can be seen that only one absorption peak of curcumin 1 crystal form is present, which also indicates complete removal of the solvent.

The performance test of the obtained product shows that: the bulk density is 0.58g/mL (model number is BT-1000 powder comprehensive characteristic tester), the repose angle is 34 degrees (model number is BT-1000 powder comprehensive characteristic tester), the purity is 99.8 percent (model number is Water2669 high performance liquid chromatograph), and the solvent residue is 43ppm (model number is Bruker gas chromatograph).

Example 2

Weighing 11g of curcumin crude powder raw material, dissolving in 100g of 1, 4-dioxane at the temperature of 60 ℃ with stirring, cooling to 43 ℃ at the cooling rate of 2 ℃/h, then heating to 48 ℃, and growing crystals for 1 h; cooling and returning to the temperature, and finally maintaining the temperature at 46 ℃ for crystal growth for 1 h; filtering, then desolventizing at 65 ℃ by using a vacuum drying oven for 12 hours, and characterizing after complete desolventizing.

By the same detection method as in example 1, it was found that: the crystal habit of the obtained product is rod-shaped, and the product is a stable 1 crystal form, the bulk density is 0.7g/mL, the angle of repose is 35 degrees, the purity is 99.7 percent, and the solution residue is 39 ppm.

Example 3

Weighing 10g of curcumin crude powder raw material, dissolving in 50g of 1, 4-dioxane at the temperature of 60 ℃ with stirring, cooling to 52 ℃ at the cooling rate of 1.5 ℃/h, then heating to 57 ℃, and growing crystals for 1.5 h; cooling and returning to the temperature, and finally maintaining the temperature at 54 ℃ for crystal growth for 1.5 h; filtering, then desolventizing at 60 ℃ by using a vacuum drying oven for 12 hours, and characterizing after the desolventizing is completed.

By the same detection method as in example 1, it was found that: the crystal habit of the obtained product is rod-shaped, and the product is a stable 1 crystal form, the bulk density is 0.69g/mL, the angle of repose is 32 degrees, the purity is 99.8 percent, and the solution residue is 27 ppm.

Example 4

Weighing 10g of curcumin crude powder raw material, dissolving in 50g of 1, 4-dioxane at 65 ℃ with stirring, cooling to 52 ℃ at a cooling rate of 1 ℃/h, then heating to 57 ℃, and growing crystals for 1.5 h; cooling and returning to the temperature, and finally maintaining the temperature at 53 ℃ for crystal growth for 1.5 h; filtering, then desolventizing at 50 ℃ by using a vacuum drying oven for 24 hours, and characterizing after the desolventizing is completed.

By the same detection method as in example 1, it was found that: the crystal habit of the obtained product is rod-shaped, and the product is a stable 1 crystal form, the bulk density is 0.71g/mL, the angle of repose is 34 degrees, the purity is 99.7 percent, and the residue is 42 ppm.

Example 5

Weighing 10g of curcumin crude powder raw material, dissolving in 100g of 1, 4-dioxane at 50 ℃ with stirring, cooling to 40 ℃ at a cooling rate of 1 ℃/h, then heating to 46 ℃, and growing crystals for 2 h; cooling and returning to the temperature, and finally maintaining the temperature at 41 ℃ for crystal growth for 2 hours; filtering, then desolventizing at 50 ℃ by using a vacuum drying oven for 24 hours, and characterizing after the desolventizing is completed.

By the same detection method as in example 1, it was found that: the crystal habit of the obtained product is rod-shaped, and the product is a stable 1 crystal form, the bulk density is 0.55g/mL, the angle of repose is 37 degrees, the purity is 99.3 percent, and the residue is 47 ppm.

Example 6

Weighing 10g of curcumin crude powder raw material, dissolving in 40g of 1, 4-dioxane at 75 ℃ with stirring, cooling to 60 ℃ at a cooling rate of 1 ℃/h, then heating to 67 ℃, and growing crystals for 1.5 h; cooling and returning to the temperature, and finally maintaining the temperature at 62 ℃ for crystal growth for 1.5 h; filtering, then desolventizing at 60 ℃ by using a vacuum drying oven for 12 hours, and characterizing after the desolventizing is completed.

By the same detection method as in example 1, it was found that: the crystal habit of the obtained product is rod-shaped, and the product is a stable 1 crystal form, the bulk density is 0.78g/mL, the angle of repose is 33 degrees, the purity is 99.8 percent, and the residue is 29 ppm.

Example 7

Weighing 10g of curcumin crude powder raw material, dissolving in 40g of 1, 4-dioxane at 75 ℃ with stirring, cooling to 60 ℃ at a cooling rate of 1.5 ℃/h, then heating to 67 ℃, and growing crystals for 2 h; cooling and returning to the temperature, and finally maintaining the temperature at 62 ℃ for crystal growth for 2 hours; filtering, then desolventizing at 60 ℃ by using a vacuum drying oven for 12 hours, and characterizing after the desolventizing is completed.

By the same detection method as in example 1, it was found that: the crystal habit of the obtained product is rod-shaped, and the product is a stable 1 crystal form, the bulk density is 0.82g/mL, the angle of repose is 32 degrees, the purity is 99.7 percent, and the residue is 31 ppm.

Example 8

Weighing 10g of curcumin crude powder raw material, dissolving in 70g of 1, 4-dioxane at 65 ℃ with stirring, cooling to 50 ℃ at a cooling rate of 1 ℃/h, then heating to 57 ℃, and growing crystals for 2 h; cooling and returning to the temperature, and finally maintaining the temperature at 52 ℃ for crystal growth for 2 hours; filtering, then desolventizing at 65 ℃ by using a vacuum drying oven for 12 hours, and characterizing after complete desolventizing.

By the same detection method as in example 1, it was found that: the crystal habit of the obtained product is rod-shaped, and the product is a stable 1 crystal form, the bulk density is 0.8g/mL, the angle of repose is 34 degrees, the purity is 99.8 percent, and the solution residue is 25 ppm.

Example 9

Weighing 11g of curcumin crude powder raw material, dissolving in 100g of 1, 4-dioxane at 65 ℃ with stirring, cooling to 40 ℃ at a cooling rate of 1 ℃/h, then heating to 48 ℃, and growing crystals for 0.5 h; cooling and returning to the temperature, and finally maintaining the temperature at 41 ℃ for crystal growth for 0.5 h; filtering, then using a vacuum drying oven to remove the solvent at 80 ℃ for 8 hours, and characterizing after the solvent is completely removed.

By the same detection method as in example 1, it was found that: the crystal habit of the obtained product is rod-shaped, and the product is a stable 1 crystal form, the bulk density is 0.52g/mL, the angle of repose is 39 degrees, the purity is 99.3 percent, and the residue is 48 ppm.

Example 10

Weighing 11g of curcumin crude powder raw material, dissolving in 90g of 1, 4-dioxane at the temperature of 60 ℃ with stirring, cooling to 42 ℃ at the cooling rate of 1 ℃/h, then heating to 50 ℃, and growing crystals for 2 h; cooling and returning to the temperature, and finally maintaining the temperature at 42 ℃ for crystal growth for 2 hours; filtering, then desolventizing at 60 ℃ by using a vacuum drying oven for 24 hours, and characterizing after the desolventizing is completed.

By the same detection method as in example 1, it was found that: the crystal habit of the obtained product is rod-shaped, and the product is a stable 1 crystal form, the bulk density is 0.54g/mL, the angle of repose is 37 degrees, the purity is 99.6 percent, and the solution residue is 38 ppm.

Comparative example 1

The only difference from example 1 is that the temperature decrease rate was controlled at 10 ℃/h.

Weighing 11g of crude curcumin raw material, dissolving in 100g of 1, 4-dioxane at 55 ℃ with stirring, cooling to 41 ℃ at a cooling rate of 10 ℃/h, then heating to 48 ℃, and growing crystals for 2 h; cooling and returning to the temperature, and finally maintaining the temperature at 43 ℃ for crystal growth for 2 hours; filtering, then desolventizing at 60 ℃ by using a vacuum drying oven for 12 hours, and characterizing after the desolventizing is completed.

By the same detection method as in example 1, it was found that: the obtained product has high moisture content, bulk density of 0.32g/mL, angle of repose of 45 degrees, purity of 98 percent and solvent residue of 426 ppm.

As can be seen from the comparison between example 1 and comparative example 1, when the temperature reduction rate is too fast, the bulk density of the obtained product is obviously reduced, the solvent residue is higher, the fluidity is poor, and the solvent residue is increased.

Comparative example 2

The only difference from example 1 is that the seeding step is not performed.

Weighing 11g of crude curcumin raw material, dissolving in 100g of 1, 4-dioxane at 55 ℃ with stirring, cooling to 41 ℃ at a cooling rate of 1 ℃/h, and then heating to 48 ℃. Then the temperature is reduced and returned to the temperature, and finally the temperature is maintained at 43 ℃. Immediately after filtration, the solvent was then removed in a vacuum drying oven at 60 ℃ for 12h and characterized after complete removal of the solvent.

By the same detection method as in example 1, it was found that: the obtained product has high moisture content, the bulk density of 0.45g/mL, the angle of repose of 43 degrees, the purity of 98.9 percent and the dissolved residue of 524 ppm.

As can be seen from the comparison between example 1 and comparative example 2, the overall particle size of the product is smaller, the bulk density is reduced, the fluidity is deteriorated, and the amount of solvent residue is increased without the crystal growing process.

Comparative example 3

The only difference from example 1 is that the temperature decrease end point temperature was changed to 35 ℃.

Weighing 11g of crude curcumin raw material, dissolving in 100g of 1, 4-dioxane at 55 ℃ with stirring, cooling to 38 ℃ at a cooling rate of 1 ℃/h, then heating to 48 ℃, and growing crystals for 2 h; cooling and returning to the temperature, and finally maintaining the temperature at 35 ℃ for crystal growth for 2 hours; filtering, then desolventizing at 60 ℃ by using a vacuum drying oven for 12 hours, and characterizing after the desolventizing is completed.

By the same detection method as in example 1, it was found that: the crystal habit part of the obtained product is rod-shaped, the bulk density is 0.39g/mL, the angle of repose is 41 degrees, the purity is 97.5 percent, and the solution residue is 342 ppm.

As can be seen from the comparison between example 1 and comparative example 3, when the temperature reduction end point is greatly reduced, the overall particle size is smaller, the bulk density is reduced, the fluidity is deteriorated, and the solvent residue is increased.

Comparative example 4

The difference from example 1 is that the temperature reduction to 41 ℃ is not included.

Weighing 11g of curcumin crude powder raw material, dissolving in 100g of 1, 4-dioxane at 55 ℃ under the condition of stirring, directly changing the temperature to 48 ℃, and growing crystals for 2h, and then controlling the temperature to 43 ℃ and growing crystals for 2 h; filtering, then desolventizing at 60 ℃ by using a vacuum drying oven for 12 hours, and characterizing after the desolventizing is completed.

Using the same test method as in example 1, it can be seen that: the crystal habit part of the obtained product is rod-shaped, the bulk density is 0.38g/mL, the angle of repose is 40 degrees, the purity is 97.5 percent, and the solvent residue is 380 ppm.

As is clear from the comparison between example 1 and comparative example 4, the bulk density of the product decreased, the purity decreased, and the solvent residue increased without the operation of raising the temperature.

Comparative example 5

The difference from the embodiment 1 is that the temperature is not increased to 48 ℃, and the crystal growth is not carried out for 2 h.

Weighing 11g of curcumin crude powder raw material, dissolving in 100g of 1, 4-dioxane at 55 ℃ with stirring, cooling to 41 ℃ at a cooling rate of 1 ℃/h, then heating to 43 ℃, and growing crystals for 2 h; filtering, then desolventizing at 60 ℃ by using a vacuum drying oven for 12 hours, and characterizing after the desolventizing is completed.

Using the same test method as in example 1, it can be seen that: the crystal habit part of the obtained product is rod-shaped, the bulk density is 0.41g/mL, the angle of repose is 45 degrees, the purity is 97.8 percent, and the solution residue is 369 ppm.

As can be seen from the comparison between example 1 and comparative example 5, when the temperature rise is insufficient, the bulk density of the product is low, the fluidity is poor, the purity is low, and the solvent residue is high.

Comparative example 6

The only difference from example 1 is that the temperature is not maintained at 43 ℃ for 2h of crystal growth.

Weighing 11g of curcumin crude powder raw material, dissolving in 100g of 1, 4-dioxane at 55 ℃ with stirring, cooling to 41 ℃ at a cooling rate of 1 ℃/h, then heating to 48 ℃, and growing crystals for 2 h; filtering, then desolventizing at 60 ℃ by using a vacuum drying oven for 12 hours, and characterizing after the desolventizing is completed.

Using the same test method as in example 1, it can be seen that: the crystal habit part of the obtained product is rod-shaped, the bulk density is 0.45g/mL, the angle of repose is 40 degrees, the purity is 98.6 percent, and the solvent residue is 180 ppm.

As can be seen from the comparison between example 1 and comparative example 6, when the crystal growth is not carried out at low temperature, the bulk density of the product is low, the fluidity is poor, the purity is low, and the solvent residue is high.

The applicant declares that the above description is only a specific embodiment of the present invention, but the scope of the present invention is not limited thereto, and it should be understood by those skilled in the art that any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope of the present invention are within the scope and disclosure of the present invention.