A Green and Efficient Extraction and Purification Method for Marigold Lutein

Abstract

This invention provides a green and efficient method for extracting and purifying lutein from marigolds, belonging to the field of extraction, separation, and purification of fat-soluble active ingredients. The invention involves pulverizing fresh or dried marigold flowers and then using an aqueous solution of dodecyl dimethyl betaine for green extraction and purification of lutein. Based on the characteristic that dodecyl dimethyl betaine forms supramolecular interfacial charges with lutein in aqueous solution, and utilizing the fact that low temperatures significantly affect the stability and morphology of micelles, the critical micelle concentration of dodecyl dimethyl betaine decreases with decreasing temperature, and the solubility of lutein in the mixed system further decreases, lutein is precipitated and aggregated. The lutein-bound state, such as lutein esters, is then saponified using an alcohol-alkali method, followed by ethanol recrystallization to obtain high-purity lutein. This new green and efficient method for extracting and purifying lutein from marigolds provides high extraction rates and high purity. The method not only improves the extraction efficiency of lutein but also has significant implications for the safe industrial production of lutein.

Description

Technical Field

[0001] This invention relates to the field of extraction, separation and purification of fat-soluble active ingredients, and specifically discloses a method for extracting and purifying lutein from marigold leaves. Background Technology

[0002] Lutein, a natural carotenoid, possesses significant antioxidant, anti-inflammatory, and photoprotective properties, demonstrating important physiological functions in preventing age-related macular degeneration, cataracts, and cardiovascular diseases. With the continued growth in global demand for natural products, lutein is increasingly widely used in food additives, pharmaceuticals, and cosmetics. Marigolds, as an ideal biological source of lutein, contain 0.6%–3.0% lutein in their flowers and are considered a "natural resource bank of lutein." Currently, commercial lutein extraction mainly relies on marigold cultivation and processing; however, technological bottlenecks in traditional extraction processes severely restrict the industry's efficiency and sustainable development.

[0003] Traditional methods for extracting lutein from marigolds typically involve organic solvent extraction, high-temperature drying, and saponification. Solvent extraction often uses organic solvents such as petroleum ether, n-hexane, and ethyl acetate, which are mostly derived from petrochemical sources, posing health risks and environmental pollution problems. Furthermore, lutein, as a heat-sensitive substance, is extremely sensitive to light, heat, and oxygen, and is prone to isomerization and degradation reactions during traditional processing, leading to a decline in extraction rate and product quality. In the pretreatment of marigolds, traditional fresh flower processing techniques (fresh picking → preservation fermentation → dehydration and drying → pulverization and granulation) have significant shortcomings. Prolonged fermentation and high-temperature drying result in substantial lutein loss; studies have shown that this process can cause 20%–30% lutein degradation. Therefore, developing a novel technology to directly extract lutein from fresh marigold flowers, avoiding losses during the drying process, has become a research hotspot and challenge in this field. Summary of the Invention

[0004] The purpose of this invention is to provide a green and efficient extraction and purification method for marigold lutein. This invention proposes a series of new extraction and purification procedures, including micellar extraction, low-temperature flocculation separation, ethyl acetate extraction, alcohol-alkali saponification, and recrystallization, which are low in risk and have high extraction efficiency and high purity of lutein.

[0005] To achieve the above-mentioned objectives, the present invention provides the following technical solution:

[0006] The process for extracting and purifying lutein from marigolds according to the present invention includes the following steps:

[0007] (1) Crush the marigolds to obtain fine marigold fragments;

[0008] (2) Marigold fragments and dodecyl dimethyl betaine were mixed at a certain material-liquid ratio to obtain a mixture. The mixture was then extracted to obtain an extract.

[0009] (3) Place the extract in a 4°C refrigerator overnight to enrich the precipitate, centrifuge, and obtain the lutein concentrate;

[0010] (4) Add ethyl acetate to the lutein concentrate for extraction, centrifuge the extract, take the supernatant, and evaporate the ethyl acetate to obtain crude lutein.

[0011] (5) Add sodium hydroxide ethanol solution to crude lutein for saponification. After saponification, neutralize the solution with HCl and adjust the pH value to about 7. Centrifuge the solution to obtain the supernatant, evaporate to dryness, and obtain lutein extract.

[0012] (6) Dissolve the lutein extract in a hot ethanol solution, recrystallize at low temperature, and centrifuge to obtain pure lutein.

[0013] Preferably, the marigolds in step (1) are one or more types of fresh or dried flowers.

[0014] Preferably, in step (2), the mass percentage of dodecyl dimethyl betaine micelles is 0.01–15 wt.%; the mass ratio of marigold to dodecyl dimethyl betaine aqueous solution micelles is 1 g: 1 mL–10 mL; the extraction includes one or more of heating reflux extraction or ultrasonic extraction; the temperature of heating reflux extraction is 30–60°C, and the extraction time is 30–120 min; the temperature of ultrasonic extraction is 30–60°C, and the time is 15–150 min.

[0015] Preferably, in step (4), the mass ratio of lutein enrichment to the volume ratio of ethyl acetate extract is 1g:1mL to 9mL, and the extraction time is 0.5h to 3h.

[0016] Preferably, in step (5), the concentration of the sodium hydroxide ethanol solution is 1% to 5%, the saponification time is 1 to 4 hours, and the saponification temperature is 40 to 60°C.

[0017] Preferably, in step (6), the concentration of lutein extract is 50–250 mg / ml; the temperature of hot ethanol is 40–70°C; the recrystallization temperature is -20–20°C; and the crystallization time is 4–48 h.

[0018] Preferably, the centrifugation speed in steps (2) to (7) is 6000 to 10000 r / min, and the centrifugation time is 6 to 10 min.

[0019] This invention provides a novel, green, and efficient extraction and purification process for marigold lutein, comprising the following steps: crushing fresh or dried marigold flowers into fragments or powder; mixing the marigold fragments or powder with an aqueous solution of sodium dodecyl sulfate at a specific material-to-liquid ratio to obtain a mixture; extracting the mixture to obtain an extract; enriching the extract at low temperature to obtain a lutein concentrate; adding ethyl acetate to the lutein concentrate for extraction; centrifuging the extract; collecting the supernatant; and rotary drying the ethyl acetate to obtain crude lutein; adding sodium hydroxide ethanol solution to the crude lutein for saponification; neutralizing the saponified solution with HCl to adjust the pH to approximately 7; centrifuging the solution; collecting the supernatant; and rotary drying to obtain a lutein extract; dissolving the lutein extract in hot ethanol solution; recrystallizing at low temperature; and centrifuging to obtain pure lutein.

[0020] This invention utilizes an aqueous solution of dodecyl dimethyl betaine to replace the organic solvents traditionally used in the industrial extraction of lutein from marigolds. The solvent is green and safe, eliminating the drawbacks of traditional extraction solvents such as flammability, explosiveness, and significant harm to human health. This not only reduces production costs but also achieves highly efficient lutein extraction. Dodecyl dimethyl betaine forms supramolecular interfacial charges with lutein in aqueous solution. Taking advantage of the fact that low temperatures significantly affect the stability and morphology of micelles, the critical micelle concentration of dodecyl dimethyl betaine decreases with decreasing temperature, further reducing the solubility of lutein in the mixed system. This leads to the precipitation and aggregation of lutein, which is then purified by saponification of lutein esters and other lutein-bound states using alcohol-alkali methods, followed by ethanol recrystallization to obtain high-purity lutein. The novel green and efficient method for extracting and purifying lutein from marigolds provided by this invention features low solvent hazard, simple operation, high extraction rate, and high purity, with a maximum extraction rate of 98.48% and a maximum purity of 98.67%. Attached Figure Description

[0021] Figure 1 Infrared spectra of purified lutein and lutein standard after extraction;

[0022] Figure 2 High-performance liquid chromatograms of crude lutein before saponification, pure lutein after saponification, and lutein standard during the extraction and purification process;

[0023] Figure 3 Scanning electron microscope images of marigold flowers before (a) and after (b) extraction;

[0024] Figure 4 A comparison chart of crude lutein before saponification, pure lutein after saponification, and lutein standard during the extraction and purification process; Detailed Implementation

[0025] This invention provides a green and efficient method for extracting and purifying marigold lutein, comprising the following steps:

[0026] (1) Crush the marigolds to obtain fine marigold fragments;

[0027] (2) Marigold fragments and dodecyl dimethyl betaine aqueous solution are mixed at a certain material-liquid ratio to obtain a mixture. The mixture is then extracted to obtain an extract.

[0028] (3) Place the extract in a 4°C refrigerator overnight to enrich the precipitate, centrifuge, and obtain the lutein concentrate;

[0029] (4) Add ethyl acetate to the lutein concentrate for extraction, centrifuge the extract, take the supernatant, and evaporate the ethyl acetate to obtain crude lutein.

[0030] (5) Add sodium hydroxide ethanol solution to crude lutein for saponification. After saponification, neutralize the solution with HCl and adjust the pH value to about 7. Centrifuge the solution to obtain the supernatant, evaporate to dryness, and obtain lutein extract.

[0031] (6) Dissolve the lutein extract in a hot ethanol solution, recrystallize at low temperature, and centrifuge to obtain pure lutein.

[0032] In this invention, the marigold in step (1) is one or more fresh or dried flowers;

[0033] In this invention, the dodecyl dimethyl betaine micelles in step (2) preferably have a mass percentage content of 0.01 to 15 wt.%, more preferably 0.02 to 0.09 wt%.

[0034] In this invention, the mass ratio of marigold to dodecyl dimethyl betaine aqueous solution is 1g:1mL to 10mL, more preferably 1g:5mL to 10mL;

[0035] In this invention, the extraction includes one or more of heating reflux extraction or ultrasonic extraction; the temperature of heating reflux extraction is preferably 30-60°C, more preferably 40-50°C, and the extraction time is preferably 30-120 min, more preferably 60-90 min; the temperature of ultrasonic extraction is preferably 30-60°C, more preferably 40-50°C, and the extraction time is preferably 15-150 min, more preferably 90-120 min.

[0036] In this invention, the preferred mass ratio of lutein enrichment to ethyl acetate extract in step (4) is 1g:1mL to 9mL, more preferably 1g:2mL to 5mL; the preferred extraction time is 0.5h to 3h, more preferably 1h to 2h.

[0037] In this invention, the concentration of sodium hydroxide ethanol solution in step (5) is preferably 1% to 5%, more preferably 2% to 4%; the saponification time is preferably 1 h to 4 h, more preferably 2 h to 3 h; and the saponification temperature is preferably 40 to 60°C, more preferably 40 to 50°C.

[0038] In this invention, the concentration of lutein extract in step (6) is preferably 50-250 mg / mL, more preferably 100-200 mg / mL; the temperature of hot ethanol is preferably 40-70℃, more preferably 50-60℃; the recrystallization temperature is preferably -20-20℃, more preferably -20-4℃; and the crystallization time is preferably 4-48 h, more preferably 12-24 h.

[0039] In this invention, the centrifugation speed in steps (2) to (7) is preferably 6000 to 10000 r / min, more preferably 8000 to 10000 r / min; the centrifugation time is preferably 6 to 10 min, more preferably 8 to 10 min.

[0040] To further illustrate the present invention, the extraction and purification method of lutein from marigold provided by the present invention will be described in detail below with reference to examples, but these should not be construed as limiting the scope of protection of the present invention.

[0041] Example 1

[0042] Dried marigold flowers were pulverized to obtain marigold powder. 100 g of marigold powder was weighed and thoroughly mixed with 100 mL of a 0.01 wt.% dodecyl dimethyl betaine aqueous solution to obtain a mixture. The mixture was placed in an ultrasonic extraction device for extraction at 30℃ for 15 min. After extraction, the mixture was centrifuged at 6000 r / min for 6 min, and the supernatant was collected to obtain a lutein extract. The lutein content in the extract was determined by high-performance liquid chromatography (HPLC); the calculated extraction rate was 34.67%. The lutein extract was placed in a 4℃ refrigerator overnight for enrichment precipitation. The precipitate was then centrifuged at 6000 r / min for 6 min to obtain a lutein concentrate with an enrichment rate of 78.58%. 1 g of lutein concentrate was extracted with 1 mL of ethyl acetate for 0.5 h. The extract was centrifuged at 6000 r / min for 6 min. The supernatant was collected, and the ethyl acetate was evaporated to dryness to obtain crude lutein. 1% sodium hydroxide ethanol solution was added to the crude lutein, and saponification was carried out at 40℃ for 1 h. After saponification, the solution was neutralized with HCl, and the pH was adjusted to approximately 7. The solution was centrifuged, and the supernatant was evaporated to dryness to obtain lutein extract with a purity of 28.67%. 50 mg of lutein extract was dissolved in 1 mL of hot ethanol solution at 40℃, and recrystallized at 20℃ for 4 h. The crystals were collected by centrifugation to obtain pure lutein with a purity of 56.56%.

[0043] Example 2

[0044] Marigold flowers were crushed to obtain marigold flower fragments. 100 g of marigold flower fragments were weighed and thoroughly mixed with 100 mL of a 0.01 wt.% aqueous solution of dodecyl dimethyl betaine to obtain a mixture. The mixture was placed in an ultrasonic extraction device for extraction at 30 ℃ for 15 min. After extraction, the mixture was centrifuged at 6000 r / min for 6 min, and the supernatant was collected to obtain a lutein extract. The lutein content in the extract was determined by high-performance liquid chromatography (HPLC); the calculated extraction rate was 38.77%. The lutein extract was placed in a 4 ℃ refrigerator overnight for enrichment precipitation. The precipitate was then centrifuged at 6000 r / min for 6 min to obtain a lutein concentrate with an enrichment rate of 80.45%. 1 g of lutein concentrate was extracted with 2 mL of ethyl acetate for 0.5 h. The extract was centrifuged at 6000 r / min for 6 min. The supernatant was collected, and the ethyl acetate was evaporated to dryness to obtain crude lutein. 1% sodium hydroxide ethanol solution was added to the crude lutein, and saponification was carried out at 40℃ for 1 h. After saponification, the solution was neutralized with HCl, and the pH was adjusted to approximately 7. The solution was centrifuged, and the supernatant was evaporated to dryness to obtain lutein extract with a purity of 23.89%. 50 mg of lutein extract was dissolved in 1 mL of hot ethanol solution at 40℃, and recrystallized at 20℃ for 4 h. The crystals were collected by centrifugation to obtain pure lutein with a purity of 58.16%.

[0045] Example 3

[0046] Dried marigold flowers were pulverized to obtain marigold powder. 100 g of marigold powder was weighed and thoroughly mixed with 1000 mL of a 1 wt.% aqueous solution of dodecyl dimethyl betaine to obtain a mixture. The mixture was placed in a reflux extraction apparatus for extraction at 50℃ for 60 min. After extraction, the mixture was centrifuged at 8000 r / min for 8 min, and the supernatant was collected to obtain a lutein extract. The lutein content in the extract was determined by high-performance liquid chromatography (HPLC); the calculated extraction rate was 88.89%. The lutein extract was placed in a 4℃ refrigerator overnight for enrichment and precipitation. The precipitate was then centrifuged at 8000 r / min for 8 min to obtain a lutein concentrate with an enrichment rate of 95.77%. 1 g of lutein concentrate was extracted with 4 mL of ethyl acetate for 1 h. The extract was centrifuged at 8000 r / min for 8 min. The supernatant was collected and evaporated to dryness to obtain crude lutein. 2% sodium hydroxide ethanol solution was added to the crude lutein and saponified at 50℃ for 2 h. After saponification, the solution was neutralized with HCl, and the pH was adjusted to approximately 7. The solution was centrifuged, and the supernatant was evaporated to dryness to obtain lutein extract with a purity of 35.22%. 100 mg of lutein extract was dissolved in 1 mL of hot ethanol solution at 50℃ and recrystallized at 4℃ for 24 h. The crystals were collected by centrifugation to obtain pure lutein with a purity of 98.33%.

[0047] Example 4

[0048] Dried marigold flowers were pulverized to obtain marigold powder. 100 g of marigold powder was weighed and thoroughly mixed with 100 mL of a 0.01 wt.% aqueous solution of dodecyl dimethyl betaine to obtain a mixture. The mixture was placed in a reflux extraction apparatus for extraction at 30℃ for 30 min. After extraction, the mixture was centrifuged at 10000 r / min for 10 min, and the supernatant was collected to obtain a lutein extract. The lutein content in the extract was determined by high-performance liquid chromatography (HPLC); the calculated extraction rate was 66.78%. The lutein extract was placed in a 4℃ refrigerator overnight for enrichment and precipitation. The precipitate was then centrifuged at 10000 r / min for 10 min to obtain a lutein concentrate with an enrichment rate of 94.44%. 1 g of lutein concentrate was extracted with 9 mL of ethyl acetate for 3 h. The extract was centrifuged at 10000 r / min for 10 min. The supernatant was collected, and the ethyl acetate was evaporated to dryness to obtain crude lutein. 5% sodium hydroxide ethanol solution was added to the crude lutein, and saponification was carried out at 60℃ for 4 h. After saponification, the solution was neutralized with HCl, and the pH was adjusted to approximately 7. The solution was centrifuged, and the supernatant was evaporated to dryness to obtain lutein extract with a purity of 46.44%. 250 mg of lutein extract was dissolved in 1 mL of 70℃ hot ethanol solution and recrystallized at -20℃ for 48 h. The crystals were collected by centrifugation to obtain pure lutein with a purity of 78.46%.

[0049] Example 5

[0050] Dried marigold flowers were pulverized to obtain marigold powder. 100 g of marigold powder was weighed and thoroughly mixed with 500 mL of a 15 wt.% aqueous solution of dodecyl dimethyl betaine to obtain a mixture. The mixture was placed in a reflux extraction apparatus for extraction at 60℃ for 120 min. After extraction, the mixture was centrifuged at 8000 r / min for 10 min, and the supernatant was collected to obtain a lutein extract. The lutein content in the extract was determined by high-performance liquid chromatography (HPLC); the calculated extraction rate was 78.67%. The lutein extract was placed in a 4℃ refrigerator overnight for enrichment and precipitation. The lutein concentrate was then obtained by centrifugation at 8000 r / min for 8 min, with an enrichment rate of 96.67%. 1 g of lutein concentrate was extracted with 5 mL of ethyl acetate for 2 h. The extract was centrifuged at 8000 r / min for 8 min. The supernatant was collected, and the ethyl acetate was evaporated to dryness to obtain crude lutein. 4% sodium hydroxide ethanol solution was added to the crude lutein, and saponification was carried out at 50℃ for 4 h. After saponification, the solution was neutralized with HCl, and the pH was adjusted to approximately 7. The solution was centrifuged, and the supernatant was evaporated to dryness to obtain lutein extract with a purity of 46.44%. 200 mg of lutein extract was dissolved in 1 mL of hot ethanol solution at 60℃ and recrystallized at -4℃ for 12 h. The crystals were collected by centrifugation to obtain pure lutein with a purity of 82.12%.

[0051] Example 6

[0052] Marigold flowers were crushed to obtain marigold flower fragments. 100 g of marigold flower fragments were weighed and thoroughly mixed with 1000 mL of a 15 wt.% aqueous solution of dodecyl dimethyl betaine to obtain a mixture. The mixture was placed in an ultrasonic extraction device for extraction at 60 ℃ for 150 min. After extraction, the mixture was centrifuged at 10000 r / min for 10 min, and the supernatant was collected to obtain a lutein extract. The lutein content in the extract was determined by high-performance liquid chromatography (HPLC); the calculated extraction rate was 90.23%. The lutein extract was placed in a 4 ℃ refrigerator overnight to enrich the precipitate. The precipitate was then centrifuged at 10000 r / min for 10 min to obtain a lutein concentrate with an enrichment rate of 94.67%. 1 g of lutein concentrate was extracted with 9 mL of ethyl acetate for 2 h. The extract was centrifuged at 10000 r / min for 10 min. The supernatant was collected, and the ethyl acetate was evaporated to dryness to obtain crude lutein. 5% sodium hydroxide ethanol solution was added to the crude lutein, and saponification was carried out at 60℃ for 4 h. After saponification, the solution was neutralized with HCl, and the pH was adjusted to approximately 7. The solution was centrifuged, and the supernatant was evaporated to dryness to obtain lutein extract with a purity of 36.43%. 100 mg of lutein extract was dissolved in 1 mL of 70℃ hot ethanol solution and recrystallized at -20℃ for 48 h. The crystals were collected by centrifugation to obtain pure lutein with a purity of 97.28%.

[0053] Example 7

[0054] Marigold flowers were crushed to obtain marigold flower fragments. 100 g of marigold flower fragments were weighed and thoroughly mixed with 500 mL of a 0.02 wt.% aqueous solution of dodecyl dimethyl betaine to obtain a mixture. The mixture was placed in an ultrasonic extraction device for extraction at 40 ℃ for 90 min. After extraction, the mixture was centrifuged at 8000 r / min for 8 min, and the supernatant was collected to obtain a lutein extract. The lutein content in the extract was determined by high-performance liquid chromatography (HPLC); the calculated extraction rate was 98.29%. The lutein extract was placed in a 4 ℃ refrigerator overnight to enrich the precipitate. The precipitate was then centrifuged at 8000 r / min for 8 min to obtain a lutein concentrate with an enrichment rate of 98.72%. 1 g of lutein concentrate was extracted with 2 mL of ethyl acetate for 1 h. The extract was centrifuged at 8000 r / min for 8 min. The supernatant was collected, and the ethyl acetate was evaporated to dryness to obtain crude lutein. 2% sodium hydroxide ethanol solution was added to the crude lutein, and saponification was carried out at 40℃ for 2 h. After saponification, the solution was neutralized with HCl, and the pH was adjusted to approximately 7. The solution was centrifuged, and the supernatant was evaporated to dryness to obtain lutein extract with a purity of 52.68%. 100 mg of lutein extract was dissolved in 1 mL of hot ethanol solution at 50℃ and recrystallized at -20℃ for 12 h. The crystals were collected by centrifugation to obtain pure lutein with a purity of 97.58%.

[0055] Example 8

[0056] Marigold flowers were crushed to obtain marigold flower fragments. 100 g of marigold flower fragments were weighed and thoroughly mixed with 1000 mL of a 0.09 wt.% aqueous solution of dodecyl dimethyl betaine to obtain a mixture. The mixture was placed in an ultrasonic extraction device for extraction at 50 ℃ for 120 min. After extraction, the mixture was centrifuged at 10000 r / min for 10 min, and the supernatant was collected to obtain a lutein extract. The lutein content in the extract was determined by high-performance liquid chromatography (HPLC); the calculated extraction rate was 98.23%. The lutein extract was placed in a 4 ℃ refrigerator overnight for enrichment precipitation. The precipitate was then centrifuged at 10000 r / min for 10 min to obtain a lutein concentrate with an enrichment rate of 98.57%. 1 g of lutein concentrate was extracted with 5 mL of ethyl acetate for 2 h. The extract was centrifuged at 10000 r / min for 10 min. The supernatant was collected, and the ethyl acetate was evaporated to dryness to obtain crude lutein. 4% sodium hydroxide ethanol solution was added to the crude lutein, and saponification was carried out at 50℃ for 3 h. After saponification, the solution was neutralized with HCl, and the pH was adjusted to approximately 7. The solution was centrifuged, and the supernatant was evaporated to dryness to obtain lutein extract with a purity of 55.87%. 200 mg of lutein extract was dissolved in 1 mL of hot ethanol solution at 60℃ and recrystallized at 4℃ for 24 h. The crystals were collected by centrifugation to obtain pure lutein with a purity of 97.68%.

[0057] Example 9

[0058] Marigold flowers were crushed to obtain marigold flower fragments. 100 g of marigold flower fragments were weighed and thoroughly mixed with 900 mL of a 0.09 wt.% aqueous solution of dodecyl dimethyl betaine to obtain a mixture. The mixture was placed in an ultrasonic extraction device for extraction at 40 ℃ for 120 min. After extraction, the mixture was centrifuged at 8000 r / min for 8 min, and the supernatant was collected to obtain a lutein extract. The lutein content in the extract was determined by high-performance liquid chromatography (HPLC); the calculated extraction rate was 98.48%. The lutein extract was placed in a 4 ℃ refrigerator overnight to enrich the precipitate. The precipitate was then centrifuged at 8000 r / min for 8 min to obtain a lutein concentrate with an enrichment rate of 98.89%. 1 g of lutein concentrate was extracted with 4 mL of ethyl acetate for 1 h. The extract was centrifuged at 8000 r / min for 8 min. The supernatant was collected, and the ethyl acetate was evaporated to dryness to obtain crude lutein. 2.5% sodium hydroxide ethanol solution was added to the crude lutein, and saponification was carried out at 50℃ for 2 h. After saponification, the solution was neutralized with HCl, and the pH was adjusted to approximately 7. The solution was centrifuged, and the supernatant was evaporated to dryness to obtain lutein extract with a purity of 56.45%. 150 mg of lutein extract was dissolved in 1 mL of 60℃ hot ethanol solution and recrystallized at 4℃ for 24 h. The crystals were collected by centrifugation to obtain pure lutein with a purity of 98.67%.

[0059] Although the above embodiments have provided a detailed description of the present invention, they are only some embodiments of the present invention, and not all embodiments. Other embodiments can be obtained based on these embodiments without creative effort, and these embodiments all fall within the protection scope of the present invention.

Claims

1. A green and efficient method for extracting and purifying marigold lutein, characterized in that, Includes the following steps: (1) Crush the marigolds to obtain fine marigold fragments; (2) Marigold fragments and dodecyl dimethyl betaine were mixed at a certain material-liquid ratio to obtain a mixture. The mixture was then extracted to obtain an extract. (3) Place the extract in a 4°C refrigerator overnight to enrich the precipitate, centrifuge, and obtain the lutein concentrate; (4) Add ethyl acetate to the lutein concentrate for extraction, centrifuge the extract, take the supernatant, and evaporate the ethyl acetate to obtain crude lutein. (5) Add sodium hydroxide ethanol solution to crude lutein for saponification. After saponification, neutralize the solution with HCl and adjust the pH value to about 7. Centrifuge the solution to obtain the supernatant, evaporate to dryness, and obtain lutein extract. (6) Dissolve the lutein extract in a hot ethanol solution, recrystallize at low temperature, and centrifuge to obtain pure lutein.

2. The extraction and purification process for lutein according to claim 1, characterized in that, The marigolds in step (1) are one or more types of fresh or dried flowers.

3. The extraction and purification process for lutein according to claim 1, characterized in that, The mass percentage of dodecyl dimethyl betaine micelles in step (2) is 0.01–15 wt.%; the mass ratio of marigold to dodecyl dimethyl betaine aqueous solution is 1 g: 1 mL–10 mL; the extraction includes one or more of heating reflux extraction or ultrasonic extraction; the temperature of heating reflux extraction is 30–60°C and the extraction time is 30–120 min; the temperature of ultrasonic extraction is 30–60°C and the time is 15–150 min.

4. The extraction and purification process for lutein according to claim 1, characterized in that, In step (4), the mass ratio of lutein concentrate to ethyl acetate extract is 1 g: 1 mL to 9 mL, and the extraction time is 0.5 h to 3 h.

5. The extraction and purification process for lutein according to claim 1, characterized in that, In step (5), the concentration of sodium hydroxide ethanol solution is 1% to 5%, the saponification time is 1 to 4 hours, and the saponification temperature is 30 to 60°C.

6. The extraction and purification process for lutein according to claim 1, characterized in that, In step (6), the concentration of lutein extract is 50–250 mg / ml, the temperature of hot ethanol is 40–70°C, the recrystallization temperature is -20–20°C, and the crystallization time is 4–48 h.

7. The extraction and purification process for lutein according to claim 1, characterized in that, In steps (2) to (7), the centrifugation speed is 6000 to 10000 r / min and the centrifugation time is 6 to 10 min.

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