High purity curcumin powder and method of extraction thereof

Abstract

The application belongs to the technical field of natural product extraction, and provides high-purity curcumin powder and an extraction method thereof. The extraction method of the high-purity curcumin powder comprises the following steps: (1) fresh turmeric is sliced, dried, and then crushed, supercritical CO2 extraction is adopted, and curcumin oil, curcumin powder, and residues are separated; (2) the residues are subjected to fermentation-type ethanol extraction to obtain an alcohol extract; (3) the curcumin powder and the alcohol extract are combined, subjected to macroporous resin adsorption, eluted with ethanol, and then concentrated to obtain a concentrated solution; and (4) the concentrated solution is recrystallized, washed, dried, and then high-purity curcumin crystals are obtained. The extraction method adopts supercritical CO2 fluid extraction coupled with fermentation-type ethanol extraction, and the technology of gradient cooling recrystallization of ethanol and water after macroporous resin adsorption, and the steps are used and operated in cooperation. The product obtained by using the extraction method has high yield and purity, low production cost, small amount of organic solvent, and is suitable for industrial production.

Description

Technical Field

[0001] This invention belongs to the field of natural product extraction technology, specifically, it relates to a high-purity curcumin powder and its extraction method. Background Technology

[0002] Curcumin is the main active ingredient in turmeric rhizomes, primarily containing curcumin (C... 21 H 20 O6) and a small amount of demethoxycurcumin (C 20 H 18 O5) and didemethoxycurcumin (C 19 H 16 O4). As a class of natural phenolic compounds, it possesses excellent antioxidant and anti-inflammatory capabilities, effectively scavenging free radicals in the body and showing significant improvement effects on inflammatory diseases such as rheumatoid arthritis and inflammatory bowel disease. Simultaneously, it can induce cancer cell apoptosis and inhibit tumor angiogenesis, demonstrating great potential in antiviral, lipid-lowering, and anti-cancer applications. Curcumin, as a natural food coloring and antioxidant, is widely used in condiments, health products, beverages, and baked goods due to its safety, non-toxicity, and vibrant color. Curcumin's antioxidant and anti-inflammatory properties have made it a star ingredient in skincare products for delaying aging, improving skin inflammation, and combating chronic inflammation, and it also has wide applications.

[0003] Curcumin extraction technologies mainly include traditional organic solvent reflux extraction, ultrasonic combined solvent extraction, and supercritical CO2 fluid extraction. Organic solvent reflux extraction involves soaking turmeric raw materials in organic solvents such as ethanol and acetone before reflux extraction. While this method is simple to operate, the use of large amounts of organic solvents increases the risk of solvent residue and poses serious safety hazards. Ultrasonic combined solvent extraction can improve extraction efficiency to some extent, but its improvement in product purity is limited, making it difficult to meet the high-end market's demand for high-purity curcumin. Supercritical CO2 fluid extraction is energy-efficient, safe, and environmentally friendly, but its curcumin yield is relatively low.

[0004] Currently, there is an urgent need for an efficient, environmentally friendly method that enables the large-scale extraction of high-purity curcumin to meet the growing demand for high-quality curcumin from the pharmaceutical, food, health product, and cosmetic industries. Summary of the Invention

[0005] To address the aforementioned shortcomings of existing technologies, the present invention aims to provide a high-purity curcumin powder and its extraction method. This extraction method employs supercritical CO2 fluid extraction coupled with fermentation-based ethanol extraction, followed by macroporous resin adsorption and gradient cooling recrystallization of ethanol and water. The synergistic effect of each step results in a product with high yield and purity, low production cost, and low organic solvent consumption, making it suitable for industrial production.

[0006] To achieve the above objectives, the solution adopted by the present invention is as follows:

[0007] A method for extracting high-purity curcumin powder includes the following steps: (1) Fresh turmeric slices are dried and pulverized, and supercritical CO2 extraction is used to separate turmeric oil, curcumin powder and residue; (2) The residue is extracted with 95.0% fermentation ethanol at a mass ratio of 1:7-9, at 70-80℃ and 100-300r / min for 1.5-2.5h to obtain an ethanol extract; (3) The curcumin powder and ethanol extract are combined, adsorbed by macroporous resin, eluted with ethanol and concentrated to obtain a concentrate; (4) The concentrate is recrystallized, washed and dried to obtain high-purity curcumin crystals.

[0008] Further, in a preferred embodiment of the present invention, step (2) involves the preparation of fermentable ethanol, including: a. raw material pretreatment: screening and removing impurities from sweet potatoes, crushing them, and adding water at a ratio of 1:3 to prepare starch slurry; b. cooking and gelatinization: cooking at 105-110℃ and 0.05MPa for 20-30 minutes, cooling to 60-62℃, and then placing the mixture into a saccharification tank; c. dynamic saccharification with compound enzymes: stage 1: 0-60 min: 60-62℃, pH 6.0-6.2, adding 0.08%-0.1%... Add α-amylase (dry weight of starch) and 0.08%-0.1% isoamylase (dry weight of starch) and stir at 150-200 rpm; Stage 2: 61-180 min: then cool to 55-58℃, adjust pH to 4.2-4.5, add 0.15%-0.2% saccharifying enzyme (dry weight of starch), and stir at 100-150 rpm; d. Fermentation: cool the saccharified liquid to 30-32℃, and inoculate with yeast (10... 6 -10 7 (CFU / mL), anaerobic fermentation for 48-60h to obtain ethanol fermentation broth with a volume fraction of 12%-15%; e. Purification: triple-effect distillation of ethanol fermentation broth to obtain fermented ethanol with a volume fraction of 95.0%.

[0009] Traditional starch-based fermentation methods for ethanol production suffer from drawbacks such as low raw material utilization, low energy consumption, long fermentation times, high environmental treatment costs, and difficulty in improving product purity. The fermented ethanol prepared under the aforementioned conditions in this application significantly improves the saccharification rate, increases starch conversion rate, and significantly shortens saccharification time through enzyme synergy and dynamic temperature control during the saccharification step, thereby reducing costs and increasing efficiency.

[0010] Further, in a preferred embodiment of the present invention, in step (4): the concentrated liquid is added dropwise with a cold ethanol-water mixed solvent at 50-60°C, filtered and washed until the water content of the system is 30-40%, and then allowed to stand for crystallization for 12 hours after being cooled to 4°C by gradient cooling to obtain curcumin crystals.

[0011] In this application, a cold ethanol-water mixture system is used, along with gradient cooling and control of crystallization temperature and time, to precipitate curcumin in crystalline form while leaving impurities in the solution. This greatly improves the purity, recovery rate, and crystal quality of curcumin, while reducing impurity residue and operating energy consumption.

[0012] Furthermore, in a preferred embodiment of the present invention, in step (4), the temperature of the cold ethanol-water mixed solvent is 5-10°C.

[0013] Furthermore, in a preferred embodiment of the present invention, fermentable ethanol is used in the cold ethanol-water mixed solvent, and the volume ratio of fermentable ethanol to water is 7:3.

[0014] Furthermore, in a preferred embodiment of the present invention, in step (4): the curcumin crystals are placed in a vacuum drying oven at a temperature of 50°C and a vacuum degree of 0.095 MPa and dried for 6-8 hours until the curcumin crystals reach a constant weight.

[0015] In this application, the boiling point of water is lowered in a vacuum environment, allowing it to evaporate rapidly at a lower temperature, thus avoiding the damage to the structure and properties of curcumin caused by high temperatures and ensuring product quality.

[0016] Further, in a preferred embodiment of the present invention, in step (3): DA-201 type macroporous resin is selected, the diameter-to-height ratio of the combined solution is controlled to be 1:10, and the flow rate is 2-3 BV / h; after adsorption, the macroporous resin is eluted with 70% ethanol at a flow rate of 1-2 BV / h to obtain the eluent; the eluent is subjected to vacuum distillation using a rotary evaporator, the water bath temperature of the rotary evaporator is set to 45℃, the vacuum degree is 0.08 MPa, and a concentrated solution with a concentration of 50-80 mg / mL is obtained.

[0017] Under the specific adsorption conditions described above, the combined solution can slowly pass through the resin column, where curcumin is adsorbed onto the resin, while most impurities flow out with the solution. During the concentration process, efficient ethanol recovery can be achieved at a lower temperature, reducing ethanol loss and avoiding adverse effects on the stability of curcumin caused by high temperatures, ultimately yielding a curcumin concentrate of suitable concentration.

[0018] Furthermore, in a preferred embodiment of the present invention, in step (1), the conditions for supercritical CO2 extraction include: extraction temperature of 35-75℃, extraction pressure of 20-28 MPa, extraction time of 2h, separation temperature of 55-60℃, pressure of primary separation vessel of 8-12MPa, and pressure of secondary separation vessel of 5 MPa.

[0019] In this application, the supercritical CO2 extraction temperature is higher than the critical temperature of CO2 (31.1℃), ensuring that the CO2 is in a supercritical state while avoiding damage to the heat sensitivity of curcumin due to excessive temperature. Under the set extraction pressure, the supercritical CO2 fluid has good solubility for curcumin, enabling efficient extraction. The separation temperature and primary separation vessel pressure settings in this application ensure effective separation of curcumin and turmeric oil within this pressure range. Curcumin is deposited as powder at the bottom of the primary separation vessel, while turmeric oil forms a floating layer. The secondary separation vessel pressure setting is used to further remove moisture and other volatile impurities from the extraction product, improving product purity. This application ensures sufficient curcumin extraction by precisely controlling the extraction temperature and time, while avoiding over-extraction that would increase energy consumption and the amount of impurities dissolved.

[0020] Furthermore, in a preferred embodiment of the present invention, step (1) of drying and pulverizing fresh turmeric slices includes: selecting fresh, mold-free, and pest-free turmeric rhizomes, washing them with running water to remove surface dirt, impurities, and microorganisms; drying the washed turmeric rhizomes at a temperature of 60°C for 12-15 hours until the moisture content of the turmeric rhizomes is 4.5-5.5%, and then pulverizing them to 20-50 mesh.

[0021] A high-purity curcumin powder was prepared using the extraction method described above.

[0022] The beneficial effects of the high-purity curcumin powder and its extraction method provided by this invention are:

[0023] (1) This invention adopts an innovative combination process of “supercritical CO2 fluid extraction coupled with fermentation-type ethanol extraction-macroporous resin adsorption-gradient cooling recrystallization of ethanol and water”, and the various technical steps form a closely coordinated technical system. Compared with the existing curcumin extraction technology, it significantly improves product quality, production efficiency, environmental performance and industrial adaptability.

[0024] (2) The extraction method for high-purity curcumin powder provided by this invention utilizes supercritical CO2 fluid extraction technology to target and extract curcumin-like active ingredients. Simultaneously, it couples fermentation-type ethanol extraction of the residue. The synergistic effect of these two methods significantly improves the extraction rate and purity of curcumin compared to traditional ethanol reflux extraction and single supercritical CO2 extraction, effectively reducing raw material loss and increasing raw material utilization. Furthermore, under the specific process parameters defined in this application, fermentation-type ethanol has a strong solubility for curcumin in the residue, resulting in rapid dissolution and diffusion of curcumin, effectively promoting its dissolution from the residue and achieving high extraction efficiency.

[0025] After extraction by coupled supercritical CO2 and fermentation-based ethanol, the impurity content in the crude extract has been significantly reduced. The subsequent macroporous resin adsorption step can further selectively adsorb curcumin, achieving preliminary purification. Finally, through gradient cooling recrystallization of ethanol and water, curcumin is precipitated in a regular crystal form by slow cooling, effectively separating residual trace impurities. The final product purity can reach over 95%, far exceeding the industry standard of 85%, and can directly meet the application needs of high-purity curcumin in the fields of pharmaceuticals and high-end health products.

[0026] (3) The extraction method of high-purity curcumin powder provided by the present invention has extremely low organic solvent residue: the present invention uses only safe fermentation ethanol as auxiliary solvent, and supercritical CO2 fluid has extremely high volatility and can be quickly removed from the extract system; the subsequent recrystallization step further removes residual ethanol through gradient cooling, and the organic solvent residue in the final product is extremely low, which completely solves the product safety hazards caused by the residue of toxic solvents such as methanol and acetone in traditional extraction processes. Attached Figure Description

[0027] Figure 1 This is a flowchart of the extraction method of high-purity curcumin powder provided in Experimental Examples 1-7 of the present invention. Detailed Implementation

[0028] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below. Where specific conditions are not specified in the embodiments, conventional conditions or conditions recommended by the manufacturer shall apply. Reagents or instruments whose manufacturers are not specified are all conventional products that can be purchased commercially.

[0029] The following is a detailed description of a high-purity curcumin powder and its extraction method provided by an embodiment of the present invention.

[0030] The features and performance of the present invention will be further described in detail below with reference to embodiments.

[0031] Example 1

[0032] This embodiment provides a method for extracting high-purity curcumin powder, including the following steps:

[0033] (1) Select 10 kg of fresh, mold-free, and pest-free turmeric rhizomes, wash them with running water to remove the soil, impurities and microorganisms attached to the surface; dry the washed turmeric rhizomes at 60℃ for 13 hours until the moisture content of the turmeric rhizomes is 5%, and then pulverize them to 20 mesh; fill the turmeric powder into the extraction vessel of the supercritical CO2 extractor. The supercritical CO2 extraction conditions include: extraction temperature of 45℃, extraction pressure of 26MPa, extraction time of 2 hours, separation temperature of 55℃, pressure of the first separation vessel of 10MPa, pressure of the second separation vessel of 5MPa, and separate turmeric oil, curcumin powder and residue.

[0034] (2) The residue was transferred to the reactor and extracted with 95.0% fermentation ethanol at a mass ratio of 1:8, at 75°C and 200r / min for 2 hours to obtain the ethanol extract.

[0035] The preparation of fermented ethanol includes: a. Raw material pretreatment: sweet potatoes are screened to remove impurities, crushed, and then mixed with water at a ratio of 1:3 to make starch slurry; b. Cooking and gelatinization: cooked at 108℃ and 0.05MPa for 25 minutes, then cooled to 61℃ and placed in a saccharification tank; c. Dynamic saccharification with compound enzymes: Stage 1: 0-60 min: at 61℃ and pH 6.1, add 0.09% of the dry weight of starch α-amylase and 0.09% of the dry weight of starch isoamylase, and stir at 180 rpm; Stage 2: 61-180 min: then cooled to 56℃, adjusted pH to 4.3, add 0.18% of the dry weight of starch saccharifying enzyme, and stir at 130 rpm; d. Fermentation: the saccharified liquid is cooled to 31℃ and inoculated with yeast (10 6 (CFU / mL), anaerobic fermentation for 50 h yields ethanol fermentation broth with a volume fraction of 13%; e. Purification: triple-effect distillation of ethanol fermentation broth yields fermented ethanol with a volume fraction of 95.0%.

[0036] (3) After combining curcumin powder and alcohol extract, DA-201 macroporous resin was selected, and the diameter-to-height ratio of the combined solution was controlled to be 1:10, and the flow rate was 2.5 BV / h. After adsorption, the macroporous resin was eluted with 70% ethanol at a flow rate of 1.5 BV / h and then centrifuged to obtain the eluent. The eluent was subjected to vacuum distillation using a rotary evaporator. The water bath temperature of the rotary evaporator was set to 45℃ and the vacuum degree was 0.08 MPa to obtain a concentrated solution with a concentration of 60 mg / mL.

[0037] (4) The concentrated liquid was added dropwise to a cold ethanol-water mixed solvent at 5°C at 55°C, filtered and washed until the water content of the system was 35%. After being cooled to 4°C by a gradient, it was allowed to stand for crystallization for 12 hours to obtain curcumin crystals. The volume ratio of fermentation ethanol to water in the cold ethanol-water mixed solvent was 7:3. Then, the curcumin crystals were placed in a vacuum drying oven at 50°C and a vacuum degree of 0.095 MPa for 7 hours until the curcumin crystals reached a constant weight to obtain curcumin powder.

[0038] Example 2

[0039] This embodiment provides a method for extracting high-purity curcumin powder, which differs from Embodiment 1 in that: in step (1), the pressure of the primary separation vessel is 8 MPa.

[0040] Example 3

[0041] This embodiment provides a method for extracting high-purity curcumin powder, which differs from Embodiment 1 in that: in step (1), the extraction temperature is 42℃. In step (2), the mass ratio of residue to fermentation type B is 1:7.

[0042] Example 4

[0043] This embodiment provides a method for extracting high-purity curcumin powder, which differs from Embodiment 1 in that: (1) 10 kg of fresh, mold-free, and pest-free turmeric rhizomes are selected and washed with running water to remove the soil, impurities and microorganisms attached to the surface; the washed turmeric rhizomes are dried at 60°C for 12 hours until the moisture content of the turmeric rhizomes is 4.5%, and then pulverized to 30 mesh; the turmeric powder is loaded into the extraction vessel of a supercritical CO2 extractor. The conditions for supercritical CO2 extraction include: extraction temperature of 35°C, extraction pressure of 20 MPa, extraction time of 2 hours, separation temperature of 58°C, pressure of the first separation vessel of 12 MPa, pressure of the second separation vessel of 5 MPa, and turmeric oil, curcumin powder and residue are separated.

[0044] (2) The residue was transferred to the reactor and extracted with 95.0% fermentation ethanol at a mass ratio of 1:7, at 70°C and 300r / min for 2.5h to obtain the ethanol extract.

[0045] (3) After combining curcumin powder and alcohol extract, DA-201 macroporous resin was selected, and the diameter-to-height ratio of the combined solution was controlled to be 1:10, and the flow rate was 2 BV / h. After adsorption, the macroporous resin was eluted with 70% ethanol at a flow rate of 1 BV / h and then centrifuged to obtain the eluent. The eluent was subjected to vacuum distillation using a rotary evaporator. The water bath temperature of the rotary evaporator was set to 45℃ and the vacuum degree was 0.08 MPa to obtain a concentrated solution with a concentration of 50 mg / mL.

[0046] (4) The concentrated solution was added dropwise to a cold ethanol-water mixed solvent at 8°C at 50°C, filtered and washed until the water content of the system was 30%. After being cooled to 4°C by a gradient, it was allowed to stand for crystallization for 12 hours to obtain curcumin crystals. The volume ratio of fermentation ethanol to water in the cold ethanol-water mixed solvent was 7:3. Then, the curcumin crystals were placed in a vacuum drying oven at 50°C and a vacuum degree of 0.095 MPa for 6 hours until the curcumin crystals reached a constant weight to obtain curcumin powder.

[0047] Example 5

[0048] This embodiment provides a method for extracting high-purity curcumin powder, which differs from Embodiment 1 in that: (1) 10 kg of fresh, mold-free, and pest-free turmeric rhizomes are selected and washed with running water to remove the soil, impurities and microorganisms attached to the surface; the washed turmeric rhizomes are dried at 60°C for 15 hours until the moisture content of the turmeric rhizomes is 5.5%, and then pulverized to 50 mesh; the turmeric powder is loaded into the extraction vessel of a supercritical CO2 extractor. The conditions for supercritical CO2 extraction include: extraction temperature of 75°C, extraction pressure of 28 MPa, extraction time of 2 hours, separation temperature of 60°C, pressure of the first separation vessel of 8 MPa, pressure of the second separation vessel of 5 MPa, and turmeric oil, curcumin powder and residue are separated.

[0049] (2) The residue was transferred to the reaction vessel and extracted with 95.0% fermentation ethanol at a mass ratio of 1:9, at 80°C and 100r / min for 1.5h to obtain the ethanol extract.

[0050] (3) After combining curcumin powder and alcohol extract, DA-201 macroporous resin was selected, and the diameter-to-height ratio of the combined solution was controlled to be 1:10, and the flow rate was 3 BV / h. After adsorption, the macroporous resin was eluted with 70% ethanol at a flow rate of 2 BV / h and then centrifuged to obtain the eluent. The eluent was subjected to vacuum distillation using a rotary evaporator. The water bath temperature of the rotary evaporator was set to 45℃ and the vacuum degree was 0.08 MPa to obtain a concentrated solution with a concentration of 80 mg / mL.

[0051] (4) The concentrated solution was added dropwise to a cold ethanol-water mixed solvent at 10°C at 60°C, filtered and washed until the water content of the system reached 40%. After being cooled to 4°C by a gradient, it was allowed to stand for crystallization for 12 hours to obtain curcumin crystals. The volume ratio of fermentation ethanol to water in the cold ethanol-water mixed solvent was 7:3. Then, the curcumin crystals were placed in a vacuum drying oven at 50°C and a vacuum degree of 0.095 MPa and dried for 8 hours until the curcumin crystals reached a constant weight to obtain curcumin powder.

[0052] Example 6

[0053] This embodiment provides a method for extracting high-purity curcumin powder, which differs from Embodiment 1 in that: in step (2), the preparation of fermentable ethanol includes: a. Raw material pretreatment: sweet potatoes are screened to remove impurities, crushed, and then water is added at a ratio of 1:3 to make starch slurry; b. Cooking and gelatinization: cooked at 105℃ and 0.05MPa for 30 minutes, then cooled to 60℃ and placed in a saccharification tank; c. Dynamic saccharification with compound enzymes: Stage 1: 0-60 min: at 60℃ and pH 6.0, 0.08% of starch dry weight of α-amylase and 0.08% of starch dry weight of isoamylase are added, and stirred at 150 rpm; Stage 2: 61-180 min: then cooled to 55℃, pH adjusted to 4.2, 0.15% of starch dry weight of saccharifying enzyme is added, and stirred at 100 rpm; d. Fermentation: the saccharified liquid is cooled to 30℃ and yeast is added (10 6 (CFU / mL), anaerobic fermentation for 48 h yielded an ethanol fermentation broth with a volume fraction of 12%; e. Purification: triple-effect distillation of the ethanol fermentation broth yielded a fermented ethanol with a volume fraction of 95.0%.

[0054] Example 7

[0055] This embodiment provides a method for extracting high-purity curcumin powder, which differs from Embodiment 1 in that: in step (2), the preparation of fermentable ethanol includes: a. Raw material pretreatment: sweet potatoes are screened to remove impurities, crushed, and then water is added at a ratio of 1:3 to make starch slurry; b. Cooking and gelatinization: cooked at 110℃ and 0.05MPa for 20 minutes, then cooled to 62℃ and placed in a saccharification tank; c. Dynamic saccharification with compound enzymes: Stage 1: 0-60 min: 62℃, pH 6.2, add 0.1% of starch dry weight of α-amylase and 0.1% of starch dry weight of isoamylase, and stir at 200rpm; Stage 2: 61-180 min: then cooled to 58℃, pH adjusted to 4.5, add 0.2% of starch dry weight of saccharifying enzyme, and stir at 100-150rpm; d. Fermentation: the saccharified liquid is cooled to 32℃ and yeast is added (10 7 (CFU / mL), anaerobic fermentation for 60 h yields 15% ethanol fermentation broth; e. Purification: triple-effect distillation of ethanol fermentation broth yields 95.0% fermented ethanol.

[0056] Comparative Example 1

[0057] This comparative example provides a method for extracting high-purity curcumin powder, which differs from Example 1 in that: in step (2), synthetic ethanol is used.

[0058] Comparative Example 2

[0059] This comparative example provides a method for extracting high-purity curcumin powder, which differs from Example 1 in that: in the preparation of fermented ethanol: c. Saccharification: Stage 1: 0-180min: 61℃, pH 6.1, add 0.09% starch dry weight of α-amylase, stir at 180rpm.

[0060] Comparative Example 3

[0061] This comparative example provides a method for extracting high-purity curcumin powder, which differs from Example 1 in that: in step (2), the preparation of fermentable ethanol includes: a. Raw material pretreatment: sweet potatoes are screened to remove impurities, crushed, and then water is added at a ratio of 1:3 to make starch slurry; b. Cooking and gelatinization: cooked at 110℃ and 0.05MPa for 20min, cooled to 62℃ and then placed in a saccharification tank; c. Dynamic saccharification with compound enzymes: Stage 1: 0-60 min: 62℃, pH 6.2, add 0.1% of starch dry weight of α-amylase and 0.1% of starch dry weight of isoamylase, and stir at 200rpm; Stage 2: 61-180 min: then cooled to 58℃, pH adjusted to 4.5, add 0.2% of starch dry weight of saccharifying enzyme, and stir at 100-150rpm; d. Fermentation: the saccharified liquid is cooled to 32℃ and yeast is added (10 7 (CFU / mL), anaerobic fermentation for 60 h yields 15% ethanol fermentation broth; e. Purification: triple-effect distillation of ethanol fermentation broth yields 95.0% fermented ethanol.

[0062] Comparative Example 4

[0063] This comparative example provides a method for extracting high-purity curcumin powder. The difference from Example 1 is that in step (2), the residue is extracted with 95.0% fermentable ethanol at a mass ratio of 1:10, at 65°C and 400r / min for 1 hour to obtain an ethanol extract.

[0064] Comparative Example 5

[0065] This comparative example provides a method for extracting high-purity curcumin powder. The difference from Example 1 is that in step (3), after combining curcumin powder and alcohol extract, DA-201 macroporous resin is selected, the diameter-to-height ratio of the combined solution is controlled to be 1:10, and the flow rate is 1 BV / h. After adsorption, the macroporous resin is eluted with 70% ethanol at a flow rate of 1 BV / h and then centrifuged to obtain the eluent.

[0066] Comparative Example 6

[0067] This comparative example provides a method for extracting high-purity curcumin powder. The difference from Example 1 is that in step (3), the eluent is subjected to vacuum distillation using a rotary evaporator. The water bath temperature of the rotary evaporator is set to 45°C and the vacuum degree is 0.08 MPa to obtain a concentrated solution with a concentration of 40 mg / mL.

[0068] Comparative Example 7

[0069] This comparative example provides a method for extracting high-purity curcumin powder, which differs from Example 1 in that: in step (4), the concentrate is added dropwise to a cold ethanol-water mixed solvent at 12°C at 65°C, filtered and washed until the water content of the system is 45%, and after being cooled to 3°C by gradient cooling, it is allowed to stand for crystallization for 8 hours to obtain curcumin crystals; in the cold ethanol-water mixed solvent, the volume ratio of fermentation ethanol to water is 6:4.

[0070] Comparative Example 8

[0071] This comparative example provides a method for extracting high-purity curcumin powder. The difference from Example 1 is that in step (4), the concentrate is added dropwise at 55°C to a cold ethanol-water mixed solvent at 5°C, filtered and washed until the water content of the system is 35%, cooled to 4°C and allowed to stand for crystallization for 12 hours to obtain curcumin crystals; in the cold ethanol-water mixed solvent, the volume ratio of fermentation ethanol to water is 7:3.

[0072] Comparative Example 9

[0073] This comparative example provides a method for extracting high-purity curcumin powder. The difference from Example 1 is that in step (4), the concentrate is filtered and washed with cold water at 5°C at 55°C until the water content of the system is 35%. After being cooled to 4°C by gradient cooling, it is allowed to stand for crystallization for 12 hours to obtain curcumin crystals.

[0074] Experimental Example 1

[0075] Experimental methods: The yield and purity of curcumin powder in Examples 1-7 and Comparative Examples 1-9 were calculated, wherein:

[0076] (1) The yield of curcumin powder was calculated as follows:

[0077] Weigh out the pretreated turmeric powder from Examples 1-7 and Comparative Examples 1-9 respectively, and record the mass as m1 (unit: g).

[0078] Weigh out the final curcumin powder obtained in Examples 1-7 and Comparative Examples 1-9 respectively, and record it as m2 (unit: g).

[0079] Yield of curcumin powder = m 2 / m1*100%.

[0080] (2) The purity of curcumin was determined by high performance liquid chromatography: referring to GB 1886.76-2015 "National Food Safety Standard for Food Additives Curcumin": where: detection equipment: Agilent-1260 liquid chromatograph; detection wavelength: 425 nm; (3) Agilent ZORBAX SB-C18 column; chromatographic conditions: mobile phase: acetonitrile-4% phosphoric acid aqueous solution, volume ratio of 48:52, flow rate: 1 mL / min, column temperature: 30-45℃, injection volume of 20 μL.

[0081] The test results are shown in Table 1.

[0082] Table 1

[0083]

[0084] As can be seen from the data in Table 1, the curcumin powder prepared by the extraction method of high-purity curcumin powder provided in Examples 1-7 of this invention has high yield and purity.

[0085] In summary, the high-purity curcumin powder and its extraction method provided by this invention are effective. This extraction method employs supercritical CO2 fluid extraction coupled with fermentation-based ethanol extraction, followed by macroporous resin adsorption and gradient cooling recrystallization of ethanol and water. The synergistic effect between each step results in a product with high yield and purity, low production cost, and low organic solvent consumption, making it suitable for industrial production.

[0086] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for extracting curcumin powder, characterized in that: Includes the following steps: (1) Fresh turmeric slices were dried and pulverized, and then extracted using supercritical CO2: the extraction temperature was 35-75℃, the extraction pressure was 20-28 MPa, the extraction time was 2h, the separation temperature was 55-60℃, the pressure of the first separation vessel was 8-12 MPa, and the pressure of the second separation vessel was 5 MPa; turmeric oil, curcumin powder and residue were separated. (2) The residue was extracted with 95.0% fermentation ethanol at a mass ratio of 1:7-9, at 70-80℃ and 100-300r / min for 1.5-2.5h to obtain an ethanol extract; The preparation of the fermented ethanol includes: a. Raw material pretreatment: screening sweet potatoes to remove impurities, crushing them, and then adding water at a ratio of 1:3 to make starch slurry; b. Cooking and gelatinization: Cook at 105-110℃ and 0.05MPa for 20-30 minutes, then cool to 60-62℃ and transfer to a saccharification tank; c. Dynamic saccharification with compound enzymes: Stage 1: 0-60 min: 60-62℃, pH 6.0-6.2, add 0.08%-0.1% of starch dry weight α-amylase and 0.08%-0.1% of starch dry weight isoamylase, stir at 150-200 rpm; Stage 2: 61-180 min: then cool to 55-58℃, adjust pH to 4.2-4.5, add 0.15%-0.2% of starch dry weight saccharifying enzyme, stir at 100-150 rpm; d. Fermentation: Cool the saccharified liquid to 30-32℃, inoculate with yeast (10 6 -10 7 (CFU / mL), anaerobic fermentation for 48-60 h to obtain an ethanol fermentation broth with a volume fraction of 12%-15%; e. Purification: triple-effect distillation of the ethanol fermentation broth to obtain the fermented ethanol with a volume fraction of 95.0%; (3) After combining the curcumin powder and the alcohol extract, the mixture is adsorbed by macroporous resin: DA-201 macroporous resin is selected, the diameter-to-height ratio of the combined solution is controlled to be 1:10, and the flow rate is 2-3 BV / h; after adsorption, the macroporous resin is eluted with 70% ethanol at a flow rate of 1-2 BV / h to obtain the eluent; the eluent is subjected to vacuum distillation using a rotary evaporator, with the water bath temperature of the rotary evaporator set to 45℃ and the vacuum degree to be 0.08 MPa, to obtain the concentrate with a concentration of 50-80 mg / mL; (4) The concentrated solution is added dropwise to a cold ethanol-water mixed solvent at a temperature of 5-10℃ at 50-60℃, filtered and washed until the water content of the system is 30-40%, and then allowed to stand for crystallization for 12h after gradient cooling to 4℃ to obtain curcumin crystals; the cold ethanol-water mixed solvent is fermentable ethanol, and the volume ratio of fermentable ethanol to water is 7:3; the curcumin crystals are placed in a vacuum drying oven at a temperature of 50℃ and a vacuum degree of 0.095 MPa and dried for 6-8h until the curcumin crystals reach constant weight.

2. The method for extracting curcumin powder according to claim 1, characterized in that: In step (1): the process of pulverizing fresh turmeric slices after drying includes: selecting fresh, mold-free, and pest-free turmeric rhizomes, washing them with running water to remove surface dirt, impurities, and microorganisms; drying the washed turmeric rhizomes at 60°C for 12-15 hours until the moisture content of the turmeric rhizomes is 4.5-5.5%, and then pulverizing them to 20-50 mesh.

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