A method for preparing astaxanthin oil

Abstract

The present application relates to astaxanthin oil technical field, specifically a kind of preparation method of astaxanthin oil, specific steps are as follows: red ball algae powder is mixed with double grain size glass beads, coconut oil is added and oscillation treatment;Subsequently, cellulase is added to carry out hydrolysis reaction, enzyme is inactivated after hydrolysis, and broken wall mixture is obtained;The broken wall mixture is extracted for the first time and extracted for the second time, and the two extraction liquids are combined and filtered;The filtrate is extracted by supercritical CO2, and the preliminary astaxanthin oil is obtained;The preliminary astaxanthin oil is mixed with 1-butyl-3-methyl imidazole hydroxide ethanol solution, nitrogen is introduced to react;After reaction, cooling filtration is carried out, and finally, the astaxanthin oil is obtained by vacuum desolventizing.In the design of the present application, 1-butyl-3-methyl imidazole hydroxide can efficiently hydrolyze the lipid impurities in astaxanthin oil to generate water-soluble fatty acid salt and glycerol, thereby improving the separation efficiency and further optimizing the separation effect.

Description

TECHNICAL FIELD

[0001] The application relates to the technical field of astaxanthin oil, and particularly relates to a preparation method of astaxanthin oil. BACKGROUND

[0002] Astaxanthin is one of the strongest natural antioxidants in nature, has multiple biological activities such as anti-inflammatory, anti-aging, cardiovascular protection, and is widely used in food, medicine and cosmetics and other fields; the main source is Haematococcus pluvialis, and astaxanthin content is as high as 3%-5%, which becomes the mainstream raw material; however, the fat-soluble and instability of natural astaxanthin lead to low bioavailability, so the market demand for astaxanthin products with high stability and high absorption rate is significantly increased, especially in functional food and anti-aging skin care products.

[0003] Due to the fact that the cell wall of Haematococcus pluvialis is composed of multiple layers of cellulose and spore powder structure, the mechanical and chemical resistance is strong, so that the traditional extraction method is difficult to efficiently destroy the cell wall, thereby reducing the release efficiency of astaxanthin; in addition, lipids, proteins and other impurities are mixed in the extraction process, which further affects the purity and extraction rate of astaxanthin, and in view of this, a preparation method of astaxanthin oil is provided. SUMMARY

[0004] The application aims to provide a preparation method of astaxanthin oil, so as to solve the problem that the cell wall of Haematococcus pluvialis is composed of multiple layers of cellulose and spore powder structure, the mechanical and chemical resistance is strong, so that the traditional extraction method is difficult to efficiently destroy the cell wall, thereby reducing the release efficiency of astaxanthin; in addition, lipids, proteins and other impurities are mixed in the extraction process, which further affects the purity and extraction rate of astaxanthin.

[0005] In order to achieve the above-mentioned purpose, the application provides a preparation method of astaxanthin oil, comprising the following steps:

[0006] S1.1, mix Haematococcus pluvialis powder and double-particle-size glass beads according to a volume ratio of 1:3, add coconut oil, and oscillate at a speed of 1000-1200 rpm for 30-45 min under the condition of 30-40 DEG C by using a vortex oscillator, and then add cellulase for hydrolysis reaction; after hydrolysis, the enzyme is inactivated to obtain a broken wall mixture;

[0007] Coconut oil contains medium-chain fatty acids, mainly including lauric acid, caprylic acid and capric acid; among them, caprylic acid and capric acid have good lipophilicity and permeability due to their short-chain structure, can penetrate the cell wall of Haematococcus pluvialis through the mechanical action of physical oscillation combined with double-size glass beads, and promote the release of cell contents such as astaxanthin; astaxanthin is a fat-soluble substance, and the polarity of coconut oil is low, which can improve its dissolution efficiency through the principle of similar dissolves similar; in addition, the proportion of saturated fatty acids in coconut oil is high, the structure is stable and resistant to high temperature, so it is not easy to be oxidized and decomposed in the oscillation process, thereby reducing the risk of degradation of astaxanthin in the process of breaking the wall.

[0008] S1.2, the broken wall mixture is subjected to primary and secondary extraction, the two extraction liquids are combined, filtered through a filter membrane with a pore size of 0.45 μm, and then the filtrate is extracted by supercritical CO2 to obtain a preliminary astaxanthin oil;

[0009] S1.3, the preliminary astaxanthin oil is mixed with 1-butyl-3-methylimidazolium hydroxide ethanol solution at a mass ratio of 1:6-10, nitrogen is introduced, and stirring is carried out at 38-40℃ and a speed of 200-250 rpm for 2-3 h;

[0010] Under alkaline conditions, 1-butyl-3-methylimidazolium hydroxide can efficiently saponify the lipid impurities in astaxanthin oil, such as triglycerides and free fatty acids, to generate water-soluble fatty acid salts (soaps) and glycerol; ethanol as a cosolvent forms a homogeneous system with the ionic liquid, improving the contact efficiency with lipid impurities, thereby significantly improving the reaction efficiency; in addition, the lipophilicity of 1-butyl-3-methylimidazole cation can wrap non-polar impurities, prompting them to separate from astaxanthin oil and enter the aqueous phase, further optimizing the separation effect.

[0011] After the reaction is completed, the reaction liquid is cooled to 4℃, and then placed for 3-4 h, and then filtered through a filter membrane with a pore size of 0.45 μm; deionized water is added to the filtrate, shaken and separated into layers, and the aqueous phase is removed, repeated 2-3 times; finally, under the conditions of 40-50℃ and -0.09~-0.08 MPa, the desorption is carried out for 30-40 min under reduced pressure to obtain astaxanthin oil.

[0012] As preferred, in S1.1, the particle sizes of the double-size glass beads are 0.5 mm and 2 mm, respectively.

[0013] Double-size glass beads refer to two kinds of glass beads with different particle sizes; glass beads with a particle size of 0.5 mm can penetrate into the intercellular space, generate local stress through high-frequency collision, and effectively weaken the cell wall structure; while glass beads with a particle size of 2 mm directly break the cell wall through violent impact, providing macroscopic damage;

[0014] The volume ratio of the glass beads with a particle size of 0.5 mm to the glass beads with a particle size of 2 mm in the double-size glass beads is 1:3.

[0015] The synergistic effect of both can significantly improve the efficiency of breaking the cell wall and avoid the limitations of a single particle size (such as insufficient impact force of small beads or uneven coverage of large beads).

[0016] Preferably, in S1.1, the mass ratio of Haematococcus pluvialis powder to coconut oil is 1:3-5.

[0017] Preferably, in S1.1, the amount of cellulase added is 1-3% of the mass of Haematococcus pluvialis powder.

[0018] The hydrolysis reaction has a pH of 6.5-7.5, a temperature of 40-45℃, a stirring speed of 150-200rpm, and a time of 1.5-3h; the enzyme inactivation conditions are 80-85℃ for 5-10min.

[0019] Preferably, in S1.2, the initial extraction step is: adding the broken cell mixture to ethanol with a mass concentration of 70-80%, stirring at 200-300rpm for 20-30min at 20-25℃, then centrifuging at 6000-8000rpm for 10-15min to separate the initial extraction liquid and the algae residue.

[0020] Preferably, in S1.2, the volume ratio of the broken cell mixture to ethanol is 1:8.

[0021] Preferably, in S1.2, the secondary extraction step is: mixing the algae residue with ethanol with a mass concentration of 90-95% at a volume ratio of 1:10, and performing leaching at 150-200rpm for 30-45min at 50-60℃.

[0022] Preferably, in S1.2, the supercritical CO2 extraction has a temperature of 31-35℃, a pressure of 25-35MPa, and a time of 2-3h.

[0023] Preferably, in S1.3, the mass concentration of 1-butyl-3-methylimidazolium hydroxide ethanol solution is 1-1.5%.

[0024] Preferably, in S1.3, the nitrogen flow is 0.5-1L / min.

[0025] Compared with the prior art, the present application has the following advantages:

[0026] 1. In the preparation method of astaxanthin oil, the high permeability of coconut oil and the synergistic effect of double particle size glass beads effectively destroy the cell wall of Haematococcus pluvialis, reducing the need for strong acid / alkali or highly toxic solvents; in addition, coconut oil is rich in saturated fatty acids and has strong antioxidant properties, thereby reducing oxidative degradation during astaxanthin extraction and improving product purity.

[0027] 2、The preparation method of astaxanthin oil, 1-butyl-3-methylimidazolium hydroxide can efficiently hydrolyze the lipid impurities in astaxanthin oil, such as triglyceride and free fatty acid, to generate water-soluble fatty acid salt (soap) and glycerol, thereby improving the separation efficiency; at the same time, the cation of 1-butyl-3-methylimidazolium hydroxide has lipophilicity, which can wrap non-polar impurities, promote them to separate from astaxanthin oil and enter the water phase, and further optimize the separation effect. DETAILED DESCRIPTION

[0028] The technical solutions in the embodiments of the present application will be clearly and completely described below in conjunction with the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor fall within the scope of protection of the present application.

[0029] Preparation of Haematococcus pluvialis powder: Haematococcus pluvialis was centrifuged at 8000-10000 rpm for 10-15 min, and the algal mud was collected; the algal mud was washed with deionized water for 2-3 times to remove the residual culture medium and salt; the algal mud was pre-cooled to-40℃, and dried under a vacuum degree of 10 Pa for 24-36 h to retain >95% astaxanthin activity; the algal block was ground to a particle size of ≤50 μm using a super micro grinder to obtain Haematococcus pluvialis powder.

[0030] Embodiment 1: A preparation method of astaxanthin oil, comprising the following steps:

[0031] S1.1, Haematococcus pluvialis powder and glass beads with particle sizes of 0.5 mm and 2 mm were mixed in a volume ratio of 1:3, coconut oil was added in a mass ratio of 1:3 with respect to the mass of Haematococcus pluvialis powder, and the mixture was oscillated at 1000 rpm for 45 min at 40℃ using a vortex oscillator; then 1% cellulase with respect to the mass of Haematococcus pluvialis powder was added, and the hydrolysis reaction was carried out at 200 rpm and pH 7.0 and 45℃ for 3 h; after the hydrolysis was completed, the enzyme was inactivated by treating at 85℃ for 10 min to obtain a broken wall mixture;

[0032] S1.2, the broken wall mixture was added to 80% ethanol with a mass concentration of 80% in a volume ratio of 1:8 with respect to the volume of the broken wall mixture, and stirred at 300 rpm for 30 min at 25℃, and then centrifuged at 6000 rpm for 15 min to separate the first extraction liquid and the algal residue;

[0033] The algal residue is mixed with ethanol with a mass concentration of 95% at a volume ratio of 1:10, and is extracted at 60°C at a speed of 200 rpm for 45 min; after the two extraction solutions are combined, they are filtered through a filter membrane with a pore size of 0.45 μm; the filtrate is extracted by supercritical CO2, at a temperature of 35°C, a pressure of 35 MPa, and for a time of 3 h, to obtain the preliminary astaxanthin oil;

[0034] S1.3, the preliminary astaxanthin oil is mixed with 1-butyl-3-methylimidazolium hydroxide ethanol solution with a mass concentration of 1.5% at a mass ratio of 1:6, nitrogen gas is introduced at a flow rate of 0.5 L / min, and stirring is performed at 40°C at a speed of 250 rpm for 3 h;

[0035] After the reaction is completed, the reaction solution is cooled to 4°C, and is left to stand for 4 h, and then is filtered through a filter membrane with a pore size of 0.45 μm; deionized water is added to the filtrate, and after oscillation and layer separation, the water phase is removed, and the operation is repeated 3 times, and finally, desolventizing is performed at 50°C, -0.09 MPa, and for 40 min under reduced pressure, to obtain the astaxanthin oil.

[0036] Example 2: A method for preparing astaxanthin oil, comprising the following steps:

[0037] S1.1, Haematococcus pluvialis powder is mixed with double-particle-size glass beads with particle sizes of 0.5 mm and 2 mm at a volume ratio of 1:3, and coconut oil is added at a mass ratio of 1:4 with respect to the Haematococcus pluvialis powder, and oscillation is performed at 40°C at a speed of 1000 rpm for 45 min using a vortex oscillator; then, cellulase is added at 1% of the mass of the Haematococcus pluvialis powder, and hydrolysis is performed at pH 7.0 and 45°C at a speed of 200 rpm for 3 h, and after the hydrolysis is completed, the enzyme is inactivated by being treated at 85°C for 10 min, to obtain a broken-wall mixture;

[0038] S1.2, the broken-wall mixture is added to ethanol with a mass concentration of 80% at a volume ratio of 1:8 with respect to the broken-wall mixture, and stirring is performed at 25°C at a speed of 300 rpm for 30 min, and then centrifugation is performed at a speed of 6000 rpm for 15 min, to separate the first extraction solution and the algal residue;

[0039] The algal residue is mixed with ethanol with a mass concentration of 95% at a volume ratio of 1:10, and is extracted at 60°C at a speed of 200 rpm for 45 min; after the two extraction solutions are combined, they are filtered through a filter membrane with a pore size of 0.45 μm; the filtrate is extracted by supercritical CO2, at a temperature of 35°C, a pressure of 35 MPa, and for a time of 3 h, to obtain the preliminary astaxanthin oil;

[0040] S1.3, the preliminary astaxanthin oil is mixed with 1-butyl-3-methylimidazolium hydroxide ethanol solution with a mass concentration of 1.5% at a mass ratio of 1:8, nitrogen gas is introduced at a flow rate of 0.5 L / min, and stirring is performed at 40°C at a speed of 250 rpm for 3 h;

[0041] After the reaction, the reaction solution was cooled to 4℃, and stood for 4h, and then filtered through a filter membrane with a pore size of 0.45μm; deionized water was added to the filtrate, and the water phase was removed after oscillation and layering, and the operation was repeated for 3 times; finally, the solution was desolvated under reduced pressure at 50℃ and -0.09MPa for 40min to obtain astaxanthin oil.

[0042] Example 3: A preparation method of astaxanthin oil, comprising the following steps:

[0043] S1.1, The Haematococcus pluvialis powder was mixed with double-particle-size glass beads with particle sizes of 0.5mm and 2mm at a volume ratio of 1:3, and coconut oil was added at a mass ratio of 1:5 to the Haematococcus pluvialis powder, and then oscillated at 1000rpm for 45min at 40℃ using a vortex oscillator; then, 1% cellulase based on the mass of the Haematococcus pluvialis powder was added, and the hydrolysis reaction was carried out at pH 7.0 and 45℃ with stirring at 200rpm for 3h; after the hydrolysis was completed, the enzyme was inactivated by treating at 85℃ for 10min to obtain a broken cell mixture;

[0044] S1.2, The broken cell mixture was added to 80% ethanol with a mass concentration of 80% at a volume ratio of 1:8 to the broken cell mixture, and stirred at 300rpm for 30min at 25℃, and then centrifuged at 6000rpm for 15min to separate the primary extraction liquid and the algal residue;

[0045] The algal residue was mixed with 95% ethanol with a mass concentration of 95% at a volume ratio of 1:10, and extracted at 200rpm for 45min at 60℃; after the two extraction liquids were combined, the mixture was filtered through a filter membrane with a pore size of 0.45μm; the filtrate was extracted by supercritical CO2, at a temperature of 35℃, a pressure of 35MPa, and for a time of 3h to obtain preliminary astaxanthin oil;

[0046] S1.3, The preliminary astaxanthin oil was mixed with 1.5% 1-butyl-3-methylimidazolium hydroxide ethanol solution with a mass concentration of 1.5% at a mass ratio of 1:10, and nitrogen gas was introduced at a flow rate of 0.5L / min, and stirred at 250rpm for 3h at 40℃;

[0047] After the reaction, the reaction solution was cooled to 4℃, and stood for 4h, and then filtered through a filter membrane with a pore size of 0.45μm; deionized water was added to the filtrate, and the water phase was removed after oscillation and layering, and the operation was repeated for 3 times; finally, the solution was desolvated under reduced pressure at 50℃ and -0.09MPa for 40min to obtain astaxanthin oil.

[0048] Example 4: A preparation method of astaxanthin oil, comprising the following steps:

[0049] S1.1 Mix Haematococcus pluvialis powder with glass beads of 0.5 mm and 2 mm in a volume ratio of 1:3. Add coconut oil in a mass ratio of 1:3 to Haematococcus pluvialis powder. Shake at 1000 rpm for 45 min at 40 °C. Then add 1% (by mass) of cellulase from Haematococcus pluvialis powder. Perform hydrolysis at 200 rpm for 3 h at pH 7.0 and 45 °C. After hydrolysis, inactivate the enzyme by treating at 85 °C for 10 min to obtain a cell wall-broken mixture.

[0050] S1.2 Add the cell wall disruption mixture to 80% ethanol at a volume ratio of 1:8 with the cell wall disruption mixture, stir at 300 rpm for 30 min at 25 °C, and then centrifuge at 6000 rpm for 15 min to separate the primary extract and algal residue.

[0051] Algal residue was mixed with 95% ethanol at a volume ratio of 1:10 and extracted at 60℃ and 200 rpm for 45 min. The two extracts were combined and filtered through a 0.45 μm pore size filter membrane. The filtrate was then extracted with supercritical CO2 at 35℃ and 35 MPa for 3 h to obtain preliminary astaxanthin oil.

[0052] S1.3. Mix the preliminary astaxanthin oil with a 1.5% (w / w) 1-butyl-3-methylimidazolium hydroxide ethanol solution at a mass ratio of 1:4, introduce nitrogen gas at a flow rate of 0.5 L / min, and stir at 250 rpm for 3 h at 40 °C.

[0053] After the reaction was completed, the reaction solution was cooled to 4°C, allowed to stand for 4 hours, and then filtered through a filter membrane with a pore size of 0.45 μm. Deionized water was added to the filtrate, and the aqueous phase was removed after shaking and separation. This process was repeated 3 times. Finally, the solution was desolvated under reduced pressure at 50°C and -0.09 MPa for 40 minutes to obtain astaxanthin oil.

[0054] Example 5: A method for preparing astaxanthin oil, comprising the following steps:

[0055] S1.1 Mix Haematococcus pluvialis powder with glass beads of 0.5 mm and 2 mm in a volume ratio of 1:3. Add coconut oil in a mass ratio of 1:1 to Haematococcus pluvialis powder. Shake at 1000 rpm for 45 min at 40 °C. Then add 1% (by mass) of cellulase from Haematococcus pluvialis powder. Perform hydrolysis at 200 rpm for 3 h at pH 7.0 and 45 °C. After hydrolysis, inactivate the enzyme by treating at 85 °C for 10 min to obtain a cell wall-breaking mixture.

[0056] S1.2 Add the cell wall disruption mixture to 80% ethanol at a volume ratio of 1:8 with the cell wall disruption mixture, stir at 300 rpm for 30 min at 25 °C, and then centrifuge at 6000 rpm for 15 min to separate the primary extract and algal residue.

[0057] Algal residue was mixed with 95% ethanol at a volume ratio of 1:10 and extracted at 60℃ and 200 rpm for 45 min. The two extracts were combined and filtered through a 0.45 μm pore size filter membrane. The filtrate was then extracted with supercritical CO2 at 35℃ and 35 MPa for 3 h to obtain preliminary astaxanthin oil.

[0058] S1.3. Mix the preliminary astaxanthin oil with a 1.5% (w / w) 1-butyl-3-methylimidazolium hydroxide ethanol solution at a mass ratio of 1:6, introduce nitrogen gas at a flow rate of 0.5 L / min, and stir at 250 rpm for 3 h at 40 °C.

[0059] After the reaction was completed, the reaction solution was cooled to 4°C, allowed to stand for 4 hours, and then filtered through a filter membrane with a pore size of 0.45 μm. Deionized water was added to the filtrate, and the aqueous phase was removed after shaking and separation. This process was repeated 3 times. Finally, the solution was desolvated under reduced pressure at 50°C and -0.09 MPa for 40 minutes to obtain astaxanthin oil.

[0060] Comparative Example 1: Using the method of Example 2, in a method for preparing astaxanthin oil, no coconut oil was added.

[0061] Comparative Example 2: Using the method of Example 2, in a method for preparing astaxanthin oil, 1-butyl-3-methylimidazolium hydroxide was not added.

[0062] This invention discloses a method for preparing astaxanthin oil, wherein the performance indicators and testing standards of the prepared astaxanthin oil are as follows:

[0063] Take 50 mg of astaxanthin oil sample, add 10 mL of dichloromethane-methanol (1:1, v / v) solution, and vortex in the dark for 5 minutes; then centrifuge at 4000 rpm for 10 minutes, collect the supernatant and filter it through a 0.22 μm organic filter membrane for later use; use pure solvent (dichloromethane-methanol) as a blank control; accurately weigh 1.0 mg of astaxanthin standard (purity ≥98%), dilute to 10 mL with dichloromethane to prepare a 100 μg / mL stock solution, and serially dilute to a standard series of 1, 5, 10, 20, and 50 μg / mL; analyze the sample by high performance liquid chromatography (HPLC), and calculate the astaxanthin content and purity of the sample by combining chromatographic conditions (such as mobile phase, detection wavelength, etc.).

[0064] The data obtained using the above testing criteria are shown in Table 1:

[0065] Table 1 Test data of Examples 1-5 and Comparative Examples 1-3

[0066]

[0067] As can be seen from Examples 1-3 and Example 4, the content and purity of astaxanthin oil continuously increase as the mass ratio of the initial astaxanthin oil to the 1-butyl-3-methylimidazolium hydroxide ethanol solution increases. 1-Butyl-3-methylimidazolium hydroxide, as an alkaline ionic liquid, hydrolyzes lipid-soluble impurities (such as triglycerides and free fatty acids) in astaxanthin oil through saponification. Its lipophilic cation (butylimidazolium) can encapsulate nonpolar impurities, forming micelle structures, thereby promoting their removal from the astaxanthin oil. Furthermore, with the increase of the proportion of 1-butyl-3-methylimidazolium hydroxide, the OH content in the system... - Increased concentration accelerates the saponification reaction kinetics, leading to more thorough decomposition of impurities and thus improving the purity of astaxanthin oil.

[0068] As can be seen from Examples 1-3 and Example 5, the content and purity of astaxanthin oil continuously increase with the increasing mass ratio of Haematococcus pluvialis powder to coconut oil. Coconut oil, as a fat-soluble solvent, increases in volume (due to the increased mass ratio) to fully wet the Haematococcus pluvialis powder particles, disrupting the cell wall structure of Haematococcus pluvialis through physical oscillation, while simultaneously dissolving the fat-soluble astaxanthin. Combined with the oscillating shear force of the dual-diameter glass beads, a higher proportion of coconut oil can form a continuous fluid phase, reducing algae powder aggregation and increasing the collision efficiency between the glass beads and the cell wall, thereby significantly improving the cell wall breakage rate. The lauric acid (C12) and decanoic acid (C10) abundant in coconut oil have the ability to chelate metal ions, such as Fe. 2+ It can inhibit free radical chain reactions and reduce the oxidative degradation of astaxanthin.

[0069] Based on the above test experiments, Example 2 is considered the optimal example.

[0070] A comparison of Example 5 and Comparative Example 1 shows that in a method for preparing astaxanthin oil, the astaxanthin content is significantly reduced when coconut oil is not added. Coconut oil, as a fat-soluble solvent and cell wall-breaking synergist, is a key medium for the release of astaxanthin from Haematococcus pluvialis cells. The dissolution rate of astaxanthin is significantly reduced when coconut oil is not added, mainly because the partition coefficient of astaxanthin in the oil phase (coconut oil) and the solid phase (algal residue) is reduced, causing astaxanthin to tend to remain in cell debris, resulting in an extremely low concentration of astaxanthin in the extract.

[0071] A comparison of Example 5 and Comparative Example 2 shows that in a method for preparing astaxanthin oil, the purity of astaxanthin is significantly reduced when 1-butyl-3-methylimidazolium hydroxide is not added. This is because lipid impurities such as triglycerides and free fatty acids cannot be converted into water-soluble saponified products through saponification, making it difficult to effectively separate them in subsequent water washing steps, resulting in increased impurity content. In addition, due to the lack of mild regulation by alkaline ionic liquid, astaxanthin undergoes isomerization due to oxidation or thermal effects, further reducing its purity.

[0072] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely preferred examples and are not intended to limit the invention. Various changes and modifications can be made to the invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the present invention as claimed. The scope of protection of the present invention is defined by the appended claims and their equivalents.

Claims

1. A method for preparing astaxanthin oil, characterized in that, Includes the following steps: S1.1 Mix Haematococcus pluvialis powder with glass beads of 0.5 mm and 2 mm in a volume ratio of 1:3, add coconut oil (mass ratio of Haematococcus pluvialis powder to coconut oil is 1:3-5), and vortex at 1000-1200 rpm for 30-45 min at 30-40℃. Then add cellulase for hydrolysis. The amount of cellulase added is 1-3% of the mass of Haematococcus pluvialis powder. The pH of the hydrolysis reaction is 6.5-7.5, the temperature is 40-45℃, the stirring speed is 150-200 rpm, and the time is 1.5-3 h. After hydrolysis, inactivate the enzyme at 80-85℃ for 5-10 min to obtain a cell wall-broken mixture. S1.2 Add the cell wall-breaking mixture to 70-80% ethanol at a volume ratio of 1:8, stir at 200-300 rpm for 20-30 min at 20-25℃, and then centrifuge at 6000-8000 rpm for 10-15 min to separate the primary extract and algal residue; mix the algal residue with 90-95% ethanol at a volume ratio of 1:10, and extract at 150-200 rpm for 30-45 min at 50-60℃ to obtain the secondary extract; combine the two extracts, filter through a 0.45 μm pore size filter membrane, and then extract the filtrate through supercritical CO2 at a temperature of 31-35℃, a pressure of 25-35 MPa, and a time of 2-3 h to obtain preliminary astaxanthin oil; S1.

3. Mix the preliminary astaxanthin oil with a 1-1.5% (w / w) 1-butyl-3-methylimidazolium hydroxide ethanol solution at a mass ratio of 1:6-10. Purge with nitrogen gas at a flow rate of 0.5-1 L / min and stir at 200-250 rpm for 2-3 h at 38-40 °C. After the reaction is complete, cool the reaction solution to 4 °C, let it stand for 3-4 h, and then filter it through a 0.45 μm pore size filter membrane. Add deionized water to the filtrate, shake to separate the layers, and remove the aqueous phase. Repeat 2-3 times. Finally, desolvate under reduced pressure at 40-50 °C and -0.09~-0.08 MPa for 30-40 min to obtain astaxanthin oil.

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