阅读说明：本技术 一种低溶剂残留的姜黄素制备方法 (Preparation method of curcumin with low solvent residue ) 是由 齐立军 彭静维 高伟 褚延伟 黄利勇 于 2019-11-12 设计创作，主要内容包括：一种低溶剂残留的姜黄素的制备方法,包括以下工艺步骤：使用溶剂对姜黄原料进行提取,将所述的提取液进行一定程度的浓缩,保温搅拌一次结晶,分离结晶得普通姜黄素,取结晶后母液脱除溶剂残留,利用低溶残母液进行二次结晶生产低溶剂残留的姜黄素。该方法在不添加结晶剂的情况下,通过对结晶程序及参数的控制获得了低溶残的姜黄素成品,节省了溶剂原料,简化了工序。(A preparation method of curcumin with low solvent residue comprises the following process steps: extracting Curcuma rhizome raw material with solvent, concentrating the extractive solution to a certain extent, stirring under heat preservation for primary crystallization, separating and crystallizing to obtain common curcumin, removing solvent residue from crystallized mother liquor, and performing secondary crystallization with low-solvent residue mother liquor to obtain curcumin with low solvent residue. The method obtains curcumin finished product with low dissolution residue by controlling crystallization procedure and parameters without adding crystallization agent, saves solvent raw materials and simplifies working procedures.)

1. A preparation method of curcumin with low solvent residue is characterized by comprising the following steps: extracting turmeric raw materials by using a solvent, concentrating the extracting solution to a certain degree, crystallizing after concentrating, filtering crystals, removing the solvent from the obtained mother liquor, adding seed crystals into the mother liquor for crystallizing, and filtering to obtain curcumin crystals with low solvent residues.

2. The method of claim 1, further comprising the steps of:

(1) preparing a turmeric extracting solution: crushing and sieving turmeric raw materials, performing heat preservation extraction on the turmeric powder by using a solvent, and filtering after the extraction is finished to obtain turmeric extract liquid;

(2) concentrating the leaching liquor: concentrating the turmeric leaching liquor obtained in the step (1);

(3) primary crystallization: cooling the concentrated leaching liquor obtained in the step (2), keeping at a constant temperature, and filtering after no crystallization;

(4) mother liquor desolventizing residue: removing residual solvent from the filtrate (mother liquor) obtained in the step (3) to below 10ppm under the condition of vacuum pumping;

(5) secondary crystallization: adding curcumin crystal nuclei with low solubility residue obtained in the step (4) as seed crystals, cooling and crystallizing;

(6) washing and drying: and (4) filtering the solution with the curcumin crystals obtained in the step (5), washing a filter cake by using a 60-95% ethanol solution, and performing vacuum drying to obtain the low-solubility residual curcumin.

3. The preparation method according to claim 2, wherein the turmeric leaching liquor of step (2) is concentrated to a solid content of 40% to 70%, preferably 42.5% to 67.5%, and more preferably 45% to 65%.

4. The preparation method according to claim 2 or 3, wherein the temperature of the concentrated solution in the step (3) is reduced to 20-60 ℃, preferably 25-55 ℃, the concentrated solution is stirred at a constant temperature, crystallized and filtered.

5. The process according to any one of claims 2 to 4, wherein the temperature for removing the residual solvent in step (4) by vacuum is 50 to 80 ℃, preferably 55 to 75 ℃, and the vacuum degree is-0.04 to-0.09 MPa.

6. The method according to claim 2 to 5, wherein the crystallization temperature in the step (5) is 40 to 60 ℃.

7. The method according to claims 2 to 6, wherein the solvent of step (1) comprises: any one or two of ethyl acetate, acetone, methanol, ethanol and isopropanol; the washing solution in step (6) is preferably 65-85% ethanol.

8. A product obtainable by the process of any one of claims 1 to 7, wherein the product has a residual solvent content of not more than 10 ppm.

9. A composition comprising the product of claim 8.

10. Use of the product or composition according to claim 8 or 9 as a functional additive or colorant for food, feed, pharmaceutical products or cosmetics.

Technical Field

The invention belongs to the field of preparation of natural extracts, and relates to a preparation method for efficiently obtaining curcumin with low solvent residue, which is suitable for industrial production.

Background

The curcumin compounds are natural yellow phenolic compounds extracted from Curcuma plants (Curcuma, etc.) of Zingiberaceae, and the curcumin compounds in Curcuma rhizome have relatively high content. Curcumin is widely applied to industries such as medicine, food, feed, dyeing and the like at present. Curcumin is a natural food pigment, can dye protein, and has strong dyeing effect; curcumin has strong anti-corrosion capability and does not generate side effect, and curcumin is often used as a natural food additive in the process of food preparation at home and abroad.

At present, the curcumin extraction process in China mainly utilizes solvent extraction, and the extraction solvent comprises organic solvents with polarity, such as ethyl acetate, acetone, ethanol, n-butanol, sodium salicylate, methanol-water, isopropanol and the like. The solvent extraction method can cause the final curcumin extraction solvent residue to be too high to be put into the production and processing fields with higher safety on raw materials, such as food, medicine and the like.

The requirements of China on food-grade curcumin are as follows: the total content of curcumin is more than or equal to 90 percent, the residue of organic solvent (normal hexane, isopropanol and ethyl acetate) is less than or equal to 50.0ppm, the total arsenic content (calculated by As) is less than or equal to 3.0ppm, and the lead (Pb) is less than or equal to 2.0 ppm. In the prior art, a plurality of methods for extracting, separating and purifying curcumin exist, and the preparation technology of low-soluble residual curcumin is also involved, for example, CN107805193A discloses a production method of low-soluble residual curcumin crystals, which obtains low-soluble residual curcumin by adding reagents such as an emulsifier, a refining agent and the like, but the process uses a large amount of organic solvents and surfactants, and the addition of the reagents not only increases the production cost, but also increases the risk of introducing new impurities. CN106866397A discloses a low-cost and high-efficiency method for extracting curcumin, which comprises the steps of leaching rhizoma zingiberis yellow with ethanol, concentrating the leaching solution, extracting with petroleum ether, concentrating, dissolving with sodium hydroxide, extracting with ethyl acetate to obtain a primary extract, dissolving the primary extract with ethanol, and then performing adsorption separation with a special tool to obtain high-purity curcumin. CN101831199A discloses a method for extracting curcumin with high extraction speed, which is characterized in that turmeric is ground into powder and then is granulated by steam, and turmeric granules obtained after granulation are extracted by an extraction method. The influence of cooling speed, stirring mode and whether seed crystal is added on curcumin crystallization yield and crystal purity is examined in the literature (Chengtong, cooling crystallization, separation and purification of curcumin, Zhejiang chemical industry, 2019, 50(5):25-27), and although the literature discloses that high-purity curcumin crystals are obtained by cooling, stirring and seed crystal addition, an organic solvent is still required to be used as a crystallizing agent in the crystallization process, the production cost and steps are increased, and no discussion is given on how to solve the problem of solvent residue.

In order to overcome the defects of the prior art, the application develops a novel, efficient and low-cost preparation method of the low-solvent-residue curcumin, and a finished product of the low-solvent-residue curcumin is obtained by controlling a crystallization program and parameters under the condition of not adding a crystallization agent.

Disclosure of Invention

The invention provides a preparation method of curcumin with low solvent residue. The method comprises the steps of drying, crushing and sieving turmeric raw materials, leaching the turmeric raw materials by using a polar solvent, concentrating the extracting solution to a certain degree, desolventizing the residual mother solution after primary crystallization, promoting secondary crystallization by using seed crystals added in the mother solution to obtain curcumin crystals with low solvent residue, performing centrifugal filtration, and washing a filter cake by using an ethanol solution with a certain concentration to obtain a finished curcumin product with low solvent residue.

In some embodiments, the turmeric leaching liquor with low solvent residue of the application is subjected to primary crystallization when the solid content reaches 40% -70%, and the crystals are obtained by separation, and the curcumin obtained by the primary crystallization can be used as a curcumin additive with low requirement on solvent residue for production and sale although the residual solvent residue is slightly high; and the subsequent residual solvent removal of the curcumin mother liquor obtains a low-solvent residual curcumin mother liquor, and the curcumin obtained by secondary crystallization of the mother liquor can reach the level that the solvent residue is less than or equal to 10ppm without further solvent removal, and can be directly added into food for application.

The method for preparing the low-soluble residual curcumin specifically comprises the following steps:

(1) preparing a turmeric extracting solution: crushing and sieving turmeric raw materials, leaching turmeric powder by using a solvent, and filtering after leaching to obtain turmeric leaching liquor;

(2) concentrating an extracting solution: concentrating the turmeric leaching liquor obtained in the step (1) until the solid content is between 40 and 70 percent;

(3) primary crystallization: controlling the temperature of the turmeric concentrated solution in the step (2) at 20-60 ℃, stirring at a low speed, and filtering after recrystallization;

(4) mother liquor desolventizing residue: vacuumizing the filtrate (namely mother liquor) obtained in the step (3) at 50-80 ℃ to remove solvent residues to below 10 ppm;

(5) secondary crystallization: and (4) adding low-solubility residual curcumin crystals as seed crystals into the low-solubility residual mother liquor obtained in the step (4), and crystallizing at 40-60 ℃.

(6) Washing and drying: filtering the solution with curcumin crystals obtained in the step (5), washing a filter cake by using a 60-95% ethanol solution, and performing vacuum drying to obtain the low-solubility residual curcumin.

As for the extraction solvent in step (1), any solvent having a dissolving power for curcumine can be selected, and the extraction solvent can be one or a combination of several of organic solvents such as ethyl acetate, acetone, methanol, ethanol and isopropanol; ethyl acetate, acetone and ethanol solutions are preferred.

Regarding the step of concentrating the extract in the step (2), any concentrating method in the field can be adopted, the concentration degree is controlled by taking the solid content as an index, and the solid content of the concentrated turmeric extract in the step (2) is controlled to be between 40 and 70 percent; preferably 42.5 to 67.5 percent; more preferably, the solid content is 45 to 65%. The solid content in this step affects the amount of crystals produced in the first crystallization and the removal effect of the solvent used in the subsequent removal of the solvent.

Regarding the crystallization step in step (3), the crystallization in this step is achieved by lowering the temperature, and after lowering the temperature, the temperature is maintained at a certain temperature to wait for crystal growth. The temperature of the crystallization process is preferably between 20 and 60 ℃; further preferably, the temperature is 25 to 55 ℃. The temperature of this step is selected to influence the crystallization effect of this step and the crystallization yield of the subsequent second crystallization. This step may be with or without agitation.

Regarding the step of removing the residual solvent in the step (4), the step is to remove the solvent under reduced pressure and heating conditions, the pressure and temperature conditions need to be controlled, and any suitable temperature and pressure can be selected on the premise of ensuring the solvent removal effect; preferably, the turmeric mother liquor obtained in the step (3) is subjected to heat preservation at 50-80 ℃ and the vacuum degree is controlled between-0.04 MPa and-0.09 MPa for residue dissolution and removal, so that the curcumin mother liquor with low solvent residue is obtained; further preferably, the temperature is 55-75 ℃, and the vacuum degree is-0.04-0.08 MPa.

Regarding the secondary crystallization step of step (5), which is a crystallization step by adding a seed crystal and reducing the temperature, the seed crystal can be selected from any high-quality curcumin crystal nucleus, preferably a low-solvent residue curcumin crystal nucleus, and the secondary crystallization step can be performed with or without stirring. The temperature of the secondary crystallization is preferably 40 to 60 ℃. Various parameters of the secondary crystallization are selected, so that the crystallization effect of the final product can be ensured, and high-quality curcumin crystals can be obtained.

The technical scheme of the invention further comprises a step (6), wherein any method can be selected to wash and dry the curcumin crystals obtained in the previous step, preferably 60-95% ethanol solution is used to wash the crystals formed by crystallization in the step (5), and vacuum drying is preferably adopted after washing to reduce the loss of curcumin in the drying process; the washing solvent further preferably has an ethanol concentration of 65% to 85%.

The preferred technical scheme of the invention comprises the following steps:

(1) preparing a turmeric extracting solution: pulverizing Curcuma rhizome, sieving, extracting with organic solvent under heat preservation, and filtering to obtain Curcuma rhizome extract, wherein the organic solvent is selected from one or more of ethyl acetate, acetone, methanol, ethanol and isopropanol;

(2) concentrating the leaching liquor: concentrating the turmeric leaching liquor obtained in the step (1) until the solid content is 45-65%;

(3) primary crystallization: cooling the concentrated leaching liquor obtained in the step (2) to 25-55 ℃, preserving heat, stirring at a low speed, and filtering after no crystallization;

(4) mother liquor desolventizing residue: vacuumizing the filtrate (mother liquor) obtained in the step (3) at the temperature of 55-75 ℃ and the vacuum degree of-0.04-0.09 MPa to remove the residual solvent to below 10 ppm;

(5) secondary crystallization: adding a curcumin crystal nucleus with low dissolution residue into the low dissolution residue mother liquor obtained in the step (4) to be used as a seed crystal, and stirring and crystallizing at 40-60 ℃;

(6) washing and drying: and (4) filtering the solution with the curcumin crystals obtained in the step (5), washing a filter cake by using a 60-95% ethanol solution, and performing vacuum drying to obtain the low-solubility residual curcumin.

The invention has the advantages of

The solid content of the leaching liquor and the temperature of the two-time crystallization are controlled, so that the curcumin with low solvent residue can be obtained, other removing steps aiming at the residual solvent are not needed, the using amount and the variety of the solvent in the process are reduced, the complicated process of removing the solvent residue is avoided, the production cost is reduced, and the production efficiency and the safety are improved.

Detailed Description

The process of the invention is described below by means of specific embodiments. In addition, the embodiments should be considered illustrative, and not restrictive, of the scope of the invention, which is defined solely by the claims.

In the following examples, solvent residues of mother liquor and curcumin finished products are detected according to the liquid chromatography described in GB 1886.76-2015 national food safety Standard food additive curcumin, and the principle is that a sample is put into a sealed balance bottle, when the residual solvent is gasified to reach balance at a certain temperature, upper layer gas is injected into a gas chromatograph for measurement, and the measurement is compared with a standard curve for quantification.

The solvent residue standard is 50mg/kg specified in GB 1886.76-2015 national food safety standard food additive curcumin as a quantitative limit, and 10ppm is determined as a detection limit according to laboratory conditions.

The recovery rate of the low-soluble residual curcumin is the weight of the low-soluble residual curcumin/(the weight of the total curcumin) × 100%