Method for extracting and purifying lutein from marigold

Abstract

The invention relates to a method for extracting and purifying lutein from marigold, which comprises the following steps: mixing a dried marigold raw material with a binary organic solvent for extraction, and concentrating an extracting solution; mixing and stirring the thick paste or the dry extract with an alcohol-water solution, standing at low temperature for crystallization, and carrying out solid-liquid separation; and dissolving the precipitate in alkane, mixing with an alcohol-water solution containing inorganic base, stirring, standing for crystallization, carrying out solid-liquid separation, harvesting crystals, and drying to obtain the product. The invention develops a brand-new method for extracting and purifying lutein from marigold, which comprises the following steps: sequentially performing binary organic solvent extraction, concentration, alcohol low-temperature treatment, high-concentration alkali alcohol saponification and crystallization treatment on a marigold raw material to obtain a lutein product with high purity and high conversion rate. The process method is low in operation difficulty, relatively low in energy consumption, safe, environment-friendly, easy to realize industrial amplification and convenient for development and preparation of downstream products.

Description

Technical Field

[0001] The present invention belongs to the technical field of lutein extraction processes, and relates to a method for extracting and purifying lutein from marigold flowers. Background Art

[0002] Marigold (Tagets erecta L) is an annual herbaceous plant of the genus Tagetes in the family Asteraceae. In recent years, due to the increasing attention to the research of natural products, people have begun to focus on the development and utilization of marigold. Lutein esters are widely present in plants such as marigold flowers, pumpkins, cabbages, and alfalfa. Among them, the content of lutein esters in marigold flowers is the most abundant. The order of lutein ester content in marigold plants from high to low is petals, stems, and leaves. The content of carotenoids in dried flowers of orange marigold varieties is 0.6%-2.5%, and lutein esters account for about 88%-92% of the total carotenoids.

[0003] Lutein esters are hydrolyzed to form lutein monomers, which can be used as food and feed colorants. At the same time, lutein has a wide range of biological activities in aspects such as antioxidant, prevention of blindness caused by retinal yellow complex disease and muscle degeneration, prevention of cancer, cardiovascular diseases, coronary heart disease, and enhancement of body immunity. Lutein has both coloring and physiological effects, and is widely used in industries such as feed additives, food additives, medicine, industrial dyes, and aquatic products. Lutein, also known as "phytoxanthin", belongs to a kind of oxygen-containing carotenoid natural pigment without vitamin A activity, with bright color, non-toxic and harmless. The main coloring component is all-trans lutein (3R, 3'R, 6'R-β, ε-carotene-3,3'-diol). The chemical formula is C 40 H 56 O2, with a relative molecular weight of 568.85, English name Lutein, aliases such as carotenoid, carotenol, phytoxanthin, nuclear lutein, marigold flower pigment, and phytoxanthin, has multiple conjugated double bonds, is a highly unsaturated structure, and has strong free radical scavenging ability and antioxidant ability. Lutein can be well dissolved in organic solvents such as acetone, ethanol, and tetrahydrofuran, is a rhombic yellow crystal with a metallic luster, is unstable to light and hydrogen, and needs to be stored in a cool and dry place.

[0004] Traditional lutein ester extraction methods include solvent extraction, supercritical extraction, ultrasonic-microwave assisted extraction, and ultra-high pressure extraction. Solvent extraction is prone to lutein ester deterioration due to high extraction temperature; although ultrasonic-microwave assisted extraction has the advantage of high extraction efficiency, it is difficult to achieve industrial batch production; although supercritical extraction can obtain extracts with high purity, it has disadvantages such as high equipment cost, difficult operation, high energy consumption, and high extraction cost; ultra-high pressure extraction technology has high requirements for equipment technology, large energy consumption, and high cost. The conventional process for extracting lutein extract is to select a solvent with good solubility for lutein ester, such as a single non-polar organic solvent or polar solvent like acetone, n-hexane, petroleum ether, dichloromethane, chloroform, tetrahydrofuran, solvent oil, etc. for extraction, filtration, concentration, and removal of solvent residues. However, the lutein extract obtained by extracting with a single non-polar solvent has poor thermal stability and light stability, while the lutein extract obtained by extracting with a single polar solvent has many impurities and low lutein content, affecting subsequent use. And in most of the technical solutions recorded in patents, highly toxic organic solvents such as acetone and tetrahydrofuran are widely used, which has a great impact on the safety of lutein, and the yield of this method is also low.

[0005] CN102796034B discloses a method for preparing crystalline lutein from marigold flower granules, that is, directly saponifying marigold flower granules with an alkaline aqueous solution, then extracting and degreasing with an alkane solvent, extracting with tetrahydrofuran, back-extracting with deionized water, refrigerating and crystallizing, filtering and drying to obtain lutein crystals with a purity of about 80%. However, as is well known, lutein ester is a fat-soluble substance, and the direct saponification of marigold flower granules with an alkaline aqueous solution has poor effects, resulting in a low yield of lutein, and there are problems such as complex process, long time consumption, and low purity of the finished product, which is not conducive to the further development and utilization of downstream products. Therefore, there is an urgent need to develop a preparation process for lutein that can be mass-produced, environmentally friendly, has a simple process, and high purity. Summary of the Invention

[0006] Aiming at the deficiencies of the prior art, the purpose of the present invention is to provide a method for extracting and purifying lutein from marigold, especially a method for extracting and purifying lutein from marigold that can be mass-produced, environmentally friendly, has a simple process, and high product purity.

[0007] To achieve the purpose of this invention, the following technical solutions are adopted:

[0008] The present invention provides a method for extracting and purifying lutein from marigold, and the method includes:

[0009] (1) Mixing the dried marigold raw material with a binary organic solvent for leaching to obtain an extract, and concentrating the extract to a thick paste or dry extract; the binary organic solvent is a mixed solvent of C4-C7 alkane and C1-C4 fatty alcohol;

[0010] (2) Mix the thick extract or dry extract with an 85% - 95% aqueous alcohol solution, let it stand at low temperature for 0.5 - 1 h to crystallize, separate the solid from the liquid, and harvest the precipitate.

[0011] (3) Dissolve the precipitate in a C4 - C7 alkane, then mix it with a 70% - 90% aqueous alcohol solution containing 15% - 25% inorganic base, stir, adjust the pH to 8 - 10, then let it stand to crystallize, separate the solid from the liquid, harvest the crystals, and dry them to obtain the product.

[0012] The present invention has developed a brand - new method for extracting and purifying lutein from marigold. The marigold raw material is successively subjected to binary organic solvent extraction of a specific type, then concentration, low - temperature alcohol treatment, high - concentration alkali - alcohol saponification, and crystallization treatment to obtain a lutein product with high purity and high conversion rate. This process method has low operation difficulty, low energy consumption, is safe, environmentally friendly, easy to achieve industrial scale - up, and is convenient for the development and preparation of downstream products.

[0013] Preferably, the marigold raw material includes marigold petals or marigold flower granules obtained by fermentation and granulation treatment.

[0014] Preferably, the C4 - C7 alkane in step (1) includes any one or a combination of at least two of n - butane, n - pentane, n - hexane, n - heptane, or petroleum ether; more preferably n - hexane and / or n - heptane.

[0015] Compared with other types of C4 - C7 alkanes, the present invention also found that when selecting n - hexane and / or n - heptane for extraction in combination with alcohol, the purity and transfer rate of the final product lutein are higher.

[0016] Preferably, the C1 - C4 fatty alcohol in step (1) includes any one or a combination of at least two of methanol, ethanol, propanol, or butanol; more preferably ethanol.

[0017] Compared with other types of C1 - C4 fatty alcohols, the present invention also found that when selecting ethanol for extraction in combination with alkane, the purity and transfer rate of the final product lutein are higher.

[0018] Preferably, the volume ratio of the C4 - C7 alkane to the C1 - C4 fatty alcohol in step (1) is (2 - 4):1, such as 2:1, 2.5:1, 3:1, 3.5:1, 4:1, etc.

[0019] When the volume ratio of the C4 - C7 alkane to the C1 - C4 fatty alcohol is (2 - 4):1, the extraction effect on the marigold raw material is better.

[0020] Preferably, the material-liquid ratio of the marigold raw material to the binary organic solvent in step (1) is 1:(8-15) g / mL, such as 1:8 g / mL, 1:9 g / mL, 1:10 g / mL, 1:11 g / mL, 1:12 g / mL, 1:13 g / mL, 1:14 g / mL, 1:15 g / mL, etc.

[0021] Preferably, the extraction in step (1) is carried out at 35°C - 45°C (such as 35°C, 37°C, 38°C, 40°C, 42°C, 45°C, etc.) for 1 - 3 times (such as 1 time, 2 times or 3 times), each time for 1 - 3 h (such as 1 h, 1.5 h, 2 h, 2.5 h, 3 h, etc.), and the extraction liquids each time are combined.

[0022] Preferably, the alcohol in step (2) includes any one or a combination of at least two of methanol, ethanol, propanol or butanol; more preferably ethanol.

[0023] Preferably, the material-liquid ratio of the thick extract or dry extract to the aqueous alcohol solution containing inorganic base in step (2) is 1:(3 - 5) g / mL, such as 1:3 g / mL, 1:3.5 g / mL, 1:4 g / mL, 1:4.5 g / mL, 1:5 g / mL, etc.

[0024] Preferably, the low temperature in step (2) is -10°C - 4°C (such as -10°C, -8°C, -6°C, -4°C, -5°C, 0°C, 1°C, 2°C, 4°C, etc.) for 0.5 - 1 h (such as 0.5 h, 0.6 h, 0.7 h, 0.8 h, 0.9 h, 1 h, etc.).

[0025] Preferably, the C4-C7 alkanes in step (3) include any one or a combination of at least two of n-butane, n-pentane, n-hexane, n-heptane or petroleum ether.

[0026] Preferably, the material-liquid ratio of the precipitate to the C4-C7 alkanes in step (3) is 1:(1 - 3) g / mL, such as 1:1 g / mL, 1:1.5 g / mL, 1:2 g / mL, 1:2.5 g / mL, 1:3 g / mL, etc.

[0027] Preferably, the material-liquid ratio of the precipitate to the aqueous alcohol solution containing inorganic base in step (3) is 1:(4 - 6) g / mL, such as 1:4 g / mL, 1:4.5 g / mL, 1:5 g / mL, 1:5.5 g / mL, 1:6 g / mL, etc.

[0028] Preferably, the alcohol in step (3) includes any one or a combination of at least two of methanol, ethanol, propanol or butanol.

[0029] Preferably, the inorganic base in step (3) includes any one or a combination of at least two of NaOH, KOH, and Na2CO3.

[0030] Preferably, the stirring treatment in step (3) is carried out at 50°C to 60°C (such as 50°C, 53°C, 55°C, 58°C, 60°C, etc.) for 1 to 5 h (such as 1 h, 2 h, 3 h, 4 h, 5 h, etc.).

[0031] Preferably, the method of adjusting the pH in step (3) is to add an inorganic acid, and the inorganic acid includes any one or a combination of at least two of HCl, H3PO4, and H2SO4; more preferably H3PO4.

[0032] Compared with other types of inorganic acids, the present invention also studies and finds that when H3PO4 is selected to adjust the pH, the purity and transfer rate of the final product lutein are higher.

[0033] Preferably, the static crystallization in step (3) is carried out at 10°C to 30°C, such as 10°C, 12°C, 15°C, 18°C, 20°C, 22°C, 25°C, 28°C, 30°C, etc.

[0034] Preferably, after harvesting the crystals in step (3), the crystals are also washed until the pH = 7 to 8 (neutral).

[0035] Preferably, the drying in step (3) is carried out under vacuum at 35°C to 45°C (such as 35°C, 37°C, 40°C, 42°C, 45°C, etc.) for 12 to 24 h (such as 12 h, 14 h, 16 h, 18 h, 20 h, 24 h, etc.).

[0036] All other specific values not listed in the numerical ranges involved in the present invention are within the protection scope of the present invention. Considering space and brevity of expression, they will not be elaborated one by one here.

[0037] Compared with the prior art, the present invention has the following beneficial effects:

[0038] The present invention develops a brand-new method for extracting and purifying lutein from marigold. The marigold raw material is successively subjected to specific types of binary organic solvent extraction, then concentration, low-temperature alcohol treatment, high-concentration alkali alcohol saponification, and crystallization treatment to obtain a lutein product with high purity and high conversion rate. This process method has low operation difficulty, low energy consumption, is safe, environmentally friendly, easy to realize industrial scale-up, and is convenient for the development and preparation of downstream products. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] Figure 1 is the appearance diagram of the harvested product in step (2) of Example 1;

[0040] Figure 2It is the appearance diagram of the harvested product in step (3) of Example 1;

[0041] Figure 3 It is the liquid phase detection diagram of the marigold granule test sample;

[0042] Figure 4 It is the liquid phase detection diagram of the lutein reference standard;

[0043] Figure 5 It is the liquid phase detection diagram of the product prepared in Example 1. Detailed implementation manners

[0044] The technical solution of the present invention will be further described below through specific implementation manners. Those skilled in the art should understand that the described embodiments are only for helping to understand the present invention and should not be regarded as specific limitations on the present invention.

[0045] The marigold raw materials involved in the following embodiments are purchased from Yunnan Chuxiong Huashi Agricultural Science and Technology Co., Ltd. The measured average lutein content in the dry marigold inflorescence is 0.27%, and the measured average lutein content in the marigold granules is 1.88%.

[0046] Example 1

[0047] This example provides a method for extracting and purifying lutein from marigold, as follows:

[0048] (1) Mix 1 kg of dry marigold granules with a binary organic solvent at a material-liquid ratio of 1:8 kg / L, perform extraction at 45 °C for 1 h to obtain an extraction solution, and then repeat the extraction operation 2 times, and combine the 3 extraction solutions; the extraction solution is concentrated to a dry extract at 55 °C and -0.65 Mpa; the binary organic solvent is a mixed solvent of n-heptane and ethanol with a volume ratio of 3:1;

[0049] (2) Mix the dry extract with an 85% ethanol aqueous solution at a material-liquid ratio of 1:3 kg / L, stir to dissolve, stand at -7 °C for 1 h to crystallize, separate the solid and liquid, and harvest the orange-red precipitate, the appearance of which is as Figure 1 shown;

[0050] (3) Dissolve the precipitate in n-heptane at a material-liquid ratio of 1:2 kg / L at 50 °C, then mix it with a 70% ethanol aqueous solution containing 20% KOH (the ratio of the precipitate to it is 1:6 g / mL), stir and process at 50 °C for 3 h, stand and crystallize at 30 °C for 1 h, adjust the pH to 9.8 with 50% H3PO4, then separate the solid and liquid at 25 °C, harvest the crystals, rinse with purified water until the effluent is nearly neutral (pH = 7-8), and dry in vacuum at 35 °C for 24 h to obtain, the appearance of which is as Figure 2 shown.

[0051] Example 2

[0052] This embodiment provides a method for extracting and purifying lutein from marigold, as follows:

[0053] (1) Mix 2 kg of dry marigold granules with a binary organic solvent at a solid-liquid ratio of 1:15 kg / L, perform extraction at 35 °C for 3 h to obtain an extract, repeat the extraction operation once, and combine the two extracts; concentrate the extract to a dry extract at 50 °C and -0.75 Mpa; the binary organic solvent is a mixed solvent of n-hexane and ethanol with a volume ratio of 2:1;

[0054] (2) Mix the dry extract with 92% ethanol aqueous solution at a solid-liquid ratio of 1:5 kg / L, stir to dissolve, stand still at -10 °C for 0.5 h to crystallize, separate the solid and liquid, and harvest the orange-red precipitate;

[0055] (3) Dissolve the precipitate in n-hexane at a solid-liquid ratio of 1:1 kg / L at 55 °C, then mix it with a 90% ethanol aqueous solution containing 15% KOH (the ratio of the precipitate to it is 1:4 g / mL), stir and process at 55 °C for 4 h, adjust the pH to 8.5 with 50% H3PO4, then stand still and crystallize at 20 °C for 1 h, separate the solid and liquid at 25 °C, harvest the crystals, wash them with purified water until the effluent is nearly neutral (pH = 7 - 8), and dry them under vacuum at 45 °C for 12 h to obtain the product.

[0056] Example 3

[0057] This embodiment provides a method for extracting and purifying lutein from marigold, as follows:

[0058] (1) Mix 10 kg of dry marigold inflorescences (crushed into coarse powder with a particle size below 10 mesh) with a binary organic solvent at a solid-liquid ratio of 1:15 kg / L, perform extraction at 40 °C for 2 h to obtain an extract, repeat the extraction operation twice, and combine the three extracts; concentrate the extract to a dry extract at 55 °C and -0.65 Mpa; the binary organic solvent is a mixed solvent of n-hexane and ethanol with a volume ratio of 4:1;

[0059] (2) Mix the dry extract with 95% ethanol aqueous solution at a solid-liquid ratio of 1:4 kg / L, stir to dissolve, stand still at -5 °C for 1 h to crystallize, separate the solid and liquid, and harvest the orange-red precipitate;

[0060] (3) Dissolve the precipitate in petroleum ether at a solid-liquid ratio of 1:1.5 kg / L at 50 °C, then mix it with a 90% ethanol aqueous solution containing 25% KOH (the ratio of the precipitate to it is 1:5 g / mL), stir and process at 60 °C for 3 h, adjust the pH to 9.2 with 15% HCl, then stand still and crystallize at 10 °C for 1 h, separate the solid and liquid at 25 °C, harvest the crystals, wash them with purified water until the effluent is nearly neutral (pH = 7 - 8), and dry them under vacuum at 40 °C for 12 h to obtain the product.

[0061] Example 4

[0062] This embodiment provides a method for extracting and purifying lutein from marigold, which is only different from Embodiment 1 in that the binary organic solvent described in step (1) is a mixed solvent of n-butane and ethanol with a volume ratio of 3:1; other conditions remain unchanged.

[0063] Embodiment 5

[0064] This embodiment provides a method for extracting and purifying lutein from marigold, which is only different from Embodiment 1 in that the binary organic solvent described in step (1) is a mixed solvent of n-heptane and methanol with a volume ratio of 3:1; other conditions remain unchanged.

[0065] Embodiment 6

[0066] This embodiment provides a method for extracting and purifying lutein from marigold, which is only different from Embodiment 1 in that the binary organic solvent described in step (1) is a mixed solvent of n-heptane and ethanol with a volume ratio of 1:1; other conditions remain unchanged.

[0067] Embodiment 7

[0068] This embodiment provides a method for extracting and purifying lutein from marigold, which is only different from Embodiment 1 in that the binary organic solvent described in step (1) is a mixed solvent of n-heptane and ethanol with a volume ratio of 5:1; other conditions remain unchanged.

[0069] Embodiment 8

[0070] This embodiment provides a method for extracting and purifying lutein from marigold, which is only different from Embodiment 1 in that the inorganic base in step (3) is replaced by NaOH from KOH; other conditions remain unchanged.

[0071] Embodiment 9

[0072] This embodiment provides a method for extracting and purifying lutein from marigold, which is only different from Embodiment 1 in that the inorganic base in step (3) is replaced by Na2CO3 from KOH; other conditions remain unchanged.

[0073] Comparative Example 1

[0074] This comparative example provides a method for extracting and purifying lutein from marigold, which is only different from Embodiment 1 in that the binary organic solvent described in step (1) is a mixed solvent of ethyl acetate and isopropanol with a volume ratio of 3:1; other conditions remain unchanged.

[0075] Comparative Example 2

[0076] This comparative example provides a method for extracting and purifying lutein from marigold, and the difference from Example 1 is only that the binary organic solvent described in step (1) is a mixed solvent of n-hexane and acetone with a volume ratio of 3:1; other conditions remain unchanged.

[0077] Comparative Example 3

[0078] This comparative example provides a method for extracting and purifying lutein from marigold, and the difference from Example 1 is only that the 70% ethanol aqueous solution containing 20% KOH in step (3) is replaced with a 70% ethanol aqueous solution containing 10% KOH, and other conditions remain unchanged.

[0079] Comparative Example 4

[0080] This comparative example provides a method for extracting and purifying lutein from marigold, and the difference from Example 1 is only that the 70% ethanol aqueous solution containing 20% KOH in step (3) is replaced with a 70% ethanol aqueous solution containing 30% KOH, and other conditions remain unchanged.

[0081] Comparative Example 5

[0082] This comparative example provides a method for extracting and purifying lutein from marigold, and the difference from Example 1 is only that the static crystallization temperature in step (2) is normal temperature 25°C.

[0083] Comparative Example 6

[0084] This comparative example provides a method for extracting and purifying lutein from marigold as follows:

[0085] (1) Mix 1 kg of dry marigold particles with a binary organic solvent at a solid-liquid ratio of 1:8 kg / L, perform extraction at 45°C for 1 h to obtain an extract, repeat the extraction operation 2 more times, and combine the 3 extracts; concentrate the extract to a dry extract at 55°C and -0.65 Mpa; the binary organic solvent is a mixed solvent of n-heptane and ethanol with a volume ratio of 3:1;

[0086] (2) Dissolve the dry extract in n-heptane at a solid-liquid ratio of 1:2 kg / L at 50°C, then mix it with a 70% ethanol aqueous solution containing 30% KOH (the ratio of the precipitate to it is 1:6 g / mL), stir at 50°C for 3 h, stand for crystallization at 30°C for 1 h, perform solid-liquid separation at 25°C, harvest the crystals, rinse with purified water until the effluent is nearly neutral (pH = 7 - 8), and dry in vacuum at 35°C for 24 h to obtain.

[0087] Test Example 1

[0088] The products prepared in Examples 1-10 and Comparative Examples 1-4 were detected for lutein content by liquid chromatography, and the purity (%) and transfer rate (%) of lutein were obtained. The detection method is as follows:

[0089] (S1) Preparation of reference substance: Accurately weigh 10 mg of lutein reference standard (the reference standard is from the National Institutes for Food and Drug Control), place it in a 100 mL volumetric flask, dissolve it with the mobile phase, and prepare a 0.1 mg / mL solution;

[0090] (S2) Preparation of test sample of marigold raw material: Weigh 5 g of fine powder of dried marigold flowers (or 1 g of marigold granules), stir and extract with 200 mL (or 40 mL) of a binary solvent of n-hexane and ethanol (3:1) at 40 °C for 2 h, centrifuge, wash the residue with a small amount of n-hexane, combine the supernatant, concentrate it to dry extract at 50 °C under -0.75 Mpa reduced pressure, add 10 mL of n-hexane to dissolve it, then saponify it with 20 mL of 15% NaOH - 90% ethanol at 55 °C for 4 h; after completion, add ethyl acetate, make up the volume to 50 mL, and take the subsequent filtrate for liquid phase detection;

[0091] (S3) Preparation of test sample of lutein finished product: Weigh 10 mg of dried lutein crystal powder, place it in a 100 mL volumetric flask, dissolve it with the mobile phase, and prepare a 0.1 mg / mL solution;

[0092] (S4) Liquid phase conditions:

[0093] Chromatographic parameters: Flow rate 1.0 mL / min, column temperature 30 °C, detection wavelength 445 nm, injection volume 10 μL;

[0094] Mobile phase: Methanol: Acetonitrile = 9:1;

[0095] Chromatographic column: Agilent SB C18 4.6×250 mm, 5 μm;

[0096] Among them, the liquid phase detection chromatogram of the test sample of marigold granules is as shown in Figure 3 shown, the liquid phase detection chromatogram of the lutein reference standard is as shown in Figure 4 shown, and the liquid phase detection chromatogram of the product of Example 1 is as shown in Figure 5 shown.

[0097] Calculate the lutein content in each group of products according to the following formula, and obtain the lutein purity (%) and lutein transfer rate (%):

[0098] Lutein content = (Liquid phase peak area of lutein test sample × Standard product concentration × Volume of test sample extraction solution) / (Liquid phase peak area of lutein standard product × Mass of dry material of marigold raw material after deducting water) × 100%.

[0099] The results are summarized in Table 1 as follows:

[0100] Table 1

[0101]

[0102]

[0103] As can be seen from the data results in Table 1, compared with the comparative example, the extraction and purification method involved in the present invention successively performs specific types of binary organic solvent extraction on the marigold raw material, then concentration, alcohol dispersion for impurity removal treatment, high-concentration alkali alcohol saponification and crystallization treatment, and can efficiently obtain lutein from the marigold raw material, with high product purity and simple and easy-to-implement operation.

[0104] The applicant declares that the present invention uses the above embodiments to illustrate the technical solutions of the present invention, but the present invention is not limited to the above embodiments, that is, it does not mean that the present invention must rely on the above embodiments to be implemented. Those skilled in the art should understand that any improvement to the present invention, the equivalent replacement of each raw material of the product of the present invention, the addition of auxiliary components, the selection of specific methods, etc. all fall within the protection scope and the disclosure scope of the present invention.

[0105] The preferred embodiments of the present invention have been described in detail above. However, the present invention is not limited to the specific details in the above embodiments. Within the scope of the technical concept of the present invention, various simple modifications can be made to the technical solutions of the present invention, and these simple modifications all belong to the protection scope of the present invention.

[0106] In addition, it should be noted that in the above specific embodiments, the various specific technical features described can be combined in any suitable manner without conflict. To avoid unnecessary repetition, the present invention will not separately describe various possible combination methods.

Claims

1. A method for extracting and purifying lutein from marigold, characterized in that: The method comprises: (1) mixing a dried marigold raw material with a binary organic solvent, extracting to obtain an extract, and concentrating the extract to a thick paste or a dry extract; the binary organic solvent is a mixed solvent of a C4-C7 alkane and a C1-C4 fatty alcohol; (2) Mixing the thick paste or dry extract with 85% to 95% alcohol aqueous solution, stirring to dissolve; standing at low temperature for 0.5 to 1 hour for crystallization, separating the solid and the liquid, and harvesting the precipitate; (3) dissolving the precipitate in a C4-C7 alkane, and then mixing it with a 70%-90% alcohol aqueous solution containing 15%-25% of an inorganic base, stirring, adjusting the pH to 8-10, standing for crystallization, separating the solid from the liquid, harvesting the crystals, and drying to obtain the product.

2. The method according to claim 1, characterized in that The marigold raw material includes marigold petals or marigold flower particles obtained by fermentation and granulation; Preferably, the C4-C7 alkane in step (1) comprises any one of n-butane, n-pentane, n-hexane, n-heptane or petroleum ether, or a combination of at least two thereof; more preferably n-hexane and / or n-heptane; Preferably, the C1-C4 fatty alcohol in step (1) comprises any one of methanol, ethanol, propanol or butanol, or a combination of at least two thereof; more preferably ethanol; Preferably, in step (1), the volume ratio of the C4-C7 alkane to the C1-C4 fatty alcohol is (2-4):

1.

3. The method according to claim 1 or 2, characterized in that: The solid-liquid ratio of the marigold raw material to the binary organic solvent in step (1) is 1:(8-15) g / mL; Preferably, the extraction in step (1) is carried out at 35-45° C. for 1 to 3 times, each time for 1 to 3 hours, and the extracts from each time are combined.

4. The method according to any one of claims 1 to 3, characterized in that The alcohol in step (2) includes any one of methanol, ethanol, propanol or butanol, or a combination of at least two thereof; ethanol is more preferred.

5. The method according to any one of claims 1 to 4, characterized in that The solid-liquid ratio of the thick paste or dry extract to the alcohol aqueous solution in step (2) is 1:(3-5) g / mL.

6. The method according to any one of claims 1 to 5, characterized in that The low temperature in step (2) is -10°C to 4°C.

7. The method according to any one of claims 1 to 6, characterized in that The C4-C7 alkane in step (3) includes any one of n-butane, n-pentane, n-hexane, n-heptane or petroleum ether, or a combination of at least two thereof; Preferably, the solid-liquid ratio of the precipitate to the C4-C7 alkane in step (3) is 1:(1-3) g / mL; Preferably, the solid-liquid ratio of the precipitate to the alcohol aqueous solution containing the inorganic base in step (3) is 1:(4-6) g / mL.

8. The method according to any one of claims 1 to 7, characterized in that The alcohol in step (3) includes any one of methanol, ethanol, propanol or butanol, or a combination of at least two thereof; Preferably, the inorganic base in step (3) includes any one of NaOH, KOH, and Na2CO3, or a combination of at least two of them.

9. The method according to any one of claims 1 to 8, characterized in that The stirring treatment in step (3) is carried out at 50° C. to 60° C. for 1 to 5 hours; Preferably, the pH is adjusted in step (3) by adding an inorganic acid, wherein the inorganic acid comprises any one of HCl, H3PO4, H2SO4 or a combination of at least two thereof; H3PO4 is more preferred. Preferably, the static crystallization in step (3) is carried out at 10°C to 30°C.

10. The method according to any one of claims 1 to 9, characterized in that After harvesting the crystals in step (3), the crystals are washed to a pH of 7 to 8; Preferably, the drying in step (3) is performed under vacuum at 35°C to 45°C for 12 to 24 hours.

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