Ultra-cold extraction method of michelia alba

Abstract

The invention relates to the technical field of low-temperature extraction, in particular to a michelia alba ultra-cold extraction method which comprises the following steps: (1) pretreatment; (2) gradient freezing and crushing; (3) low-temperature synergistic extraction; (4) carrying out supercritical COpurification; (5) molecular distillation refining; through cooperation of a series of specific extraction steps, efficient and environment-friendly extraction of active ingredients of michelia alba is realized. Compared with a traditional extraction method, the low-temperature extraction process disclosed by the invention has the advantages that heat-sensitive components in michelia alba can be reserved to the greatest extent, the extraction rate of active components such as total flavonoids and volatile oil is remarkably increased, the oxidation resistance of the product is effectively improved, and the low-temperature extraction process has a wide application prospect in the field of medicine and health care; meanwhile, high-quality raw materials can be provided for industries such as spices and cosmetics.

Description

Technical Field

[0001] The present invention relates to the technical field of low-temperature extraction, and specifically to an ultra-cold extraction method for Michelia alba DC. Background Art

[0002] As an evergreen tree of the genus Michelia in the Magnoliaceae family, Michelia alba DC. is widely distributed in tropical and subtropical regions, and is also extensively planted in many places in southern China. Its flowers are white and elegant, with a fragrant and rich aroma. It not only has extremely high ornamental value, but also contains rich bioactive components, and has important application values in multiple fields.

[0003] Michelia alba DC. contains various active components, such as flavonoid compounds, volatile oils, etc. Flavonoids have multiple biological activities such as antioxidant, anti-inflammatory, and antibacterial effects, and can be used in the pharmaceutical and health care fields for the prevention and treatment of cardiovascular diseases, anti-aging, etc.; its volatile oil components have a unique aroma and are important raw materials for preparing high-grade fragrances, perfumes, and natural essences, and are widely used in the cosmetics and food industries.

[0004] However, at present, the extraction of active components from Michelia alba DC. faces many challenges. The traditional steam distillation method is a commonly used extraction method, but it is carried out under high-temperature conditions, and the thermosensitive components in Michelia alba DC. are easily damaged, resulting in serious loss of aroma components in the volatile oil, making the aroma of the extracted product not pure and strong enough, and the extraction rate of active components such as total flavonoids is relatively low. Therefore, developing an efficient extraction method that can retain its active components to the greatest extent is the problem that needs to be solved currently. Summary of the Invention

[0005] In view of the problems existing in the prior art, the present invention provides an ultra-cold extraction method for Michelia alba DC.

[0006] To achieve the above object, the present invention provides the following technical solutions:

[0007] An ultra-cold extraction method for Michelia alba DC. includes the following steps:

[0008] (1) Pretreatment: Place fresh Michelia alba DC. petals in deionized water containing 0.1 - 0.2% citric acid and ultrasonically clean for 3 - 4 min. After centrifugal dehydration, spread them out flat in a vacuum freeze dryer and dry at -50°C and 0.01 - 0.02 mbar until the moisture content ≤ 5%;

[0009] (2) Gradient freezing and crushing: Place the dried petals in a spiral conveyor device pre-cooled with liquid nitrogen, cool them at a rate of 5 - 7°C / min to -40°C, maintain for 10 - 15 min and then continue to cool to -60°C, maintain for 10 - 15 min and then continue to cool to -80°C, and make the cell wall crushing rate ≥ 95% through mechanical extrusion;

[0010] (3) Low-temperature co-extraction: Mix the crushed petal powder with the natural deep eutectic solvent in a ratio of 1:8 - 10, and perform pulsed microwave-assisted extraction at -15°C. Extract for 3 cycles, 10 minutes each time, to obtain the extract solution;

[0011] (4) Supercritical CO2 purification: After filtering the extract solution through a 0.22 μm ceramic membrane, perform supercritical fluid extraction and collect the light-phase fraction rich in volatile components;

[0012] (5) Molecular distillation refinement: Perform molecular distillation on the light-phase fraction at a vacuum degree of 0.05 - 0.08 Pa and a temperature of 55 - 60°C to separate the heavy-phase fraction and obtain the Michelia alba extract.

[0013] As a further technical solution, during the mechanical extrusion in step (2), pulsed vibration is applied at a frequency of 30 kHz at -80°C, and the treatment time is 10 - 12 minutes.

[0014] As a further technical solution, the natural deep eutectic solvent in step (3) is composed of choline chloride and glycerol;

[0015] where the molar ratio of choline chloride to glycerol is 1:2 - 2.5.

[0016] As a further technical solution, in step (3), 0.05 - 0.08 wt% of β-cyclodextrin is added to the natural deep eutectic solvent as a complexing agent during the extraction process.

[0017] As a further technical solution, the parameters of the pulsed microwave-assisted extraction in step (3) are a microwave power of 300 W and a duty cycle of 1:3.

[0018] As a further technical solution, after the pulsed microwave-assisted extraction in step (3), the supernatant is collected by centrifugal separation, and the precipitate part is subjected to secondary extraction;

[0019] The rotational speed of the centrifugal separation is 12000 r / min, and the time is 15 - 20 minutes.

[0020] As a further technical solution, the supercritical CO2 extraction in step (4) is carried out in three stages, including the first stage, the second stage, and the third stage.

[0021] As a further technical solution, among them, the first stage: the pressure is 25 - 28 MPa, the temperature is 40 - 42°C, the CO2 flow rate is 20 - 22 L / h, and the extraction time is 30 minutes;

[0022] The second stage: the pressure is 30 - 35 MPa, the temperature is 45 - 48°C, the CO2 flow rate is 24 - 26 L / h, and the extraction time is 20 minutes;

[0023] The third stage: the pressure is 35 - 38 MPa, the temperature is 50 - 54 °C, the CO2 flow rate is 28 - 30 L / h, and the extraction time is 10 min.

[0024] As a further technical solution, the heavy-phase fraction after molecular distillation in step (5) is returned to step (4) for cyclic extraction, and the total solvent recovery rate ≥ 99.5%.

[0025] As a further technical solution, the extract of Michelia alba prepared by the method is used to prepare cosmetics with antioxidant and soothing effects, and the addition amount is 0.1 - 1.5% (w / w).

[0026] Compared with the prior art, the beneficial effects of the present invention are:

[0027] Through the cooperation of a series of specific extraction steps, the present invention realizes the efficient and environmentally friendly extraction of the active ingredients of Michelia alba. Compared with the traditional extraction method, the low-temperature extraction process of the present invention can retain the thermosensitive components in Michelia alba to the greatest extent, significantly improve the extraction rates of active ingredients such as total flavonoids and volatile oils, effectively enhance the antioxidant performance of the product, and has broad application prospects in the fields of medicine and health care; at the same time, the relatively high aroma components can provide high-quality raw materials for industries such as spices and cosmetics.

[0028] In the treatment in the pretreatment stage of the present invention, citric acid can not only effectively remove impurities and microorganisms on the surface of the petals, but also inhibit the activity of polyphenol oxidase, prevent the petals from browning during the subsequent treatment process, and thus protect the active ingredients from being oxidized and damaged. Ultrasonic cleaning uses the cavitation effect of ultrasonic waves to clean the petals more efficiently and will not damage the tissue structure of the petals. Subsequently, vacuum freeze-drying is carried out to sublimate the water in the petals under low-temperature and low-pressure environments, avoiding the loss of active ingredients caused by high-temperature drying, and laying a good foundation for the subsequent extraction work.

[0029] Gradient freeze-crushing is adopted. This gradient cooling method enables the water in the petal cells to gradually form ice crystals. The expansion of the ice crystals generates uniform pressure on the cell walls. Under the synergistic action of subsequent mechanical extrusion and 30 kHz frequency pulse vibration at -80 °C, the cell wall fragmentation rate ≥ 95%. Compared with the traditional crushing method, this method can achieve efficient crushing at low temperature, avoid the degradation of active ingredients caused by temperature rise, and at the same time make the active ingredients in the cells more easily released, creating favorable conditions for subsequent extraction.

[0030] The present invention adopts a low-temperature synergistic extraction method combining natural deep eutectic solvents with pulsed microwave-assisted extraction. Natural deep eutectic solvents have the advantages of low toxicity, biodegradability, good solubility, etc., and can more effectively dissolve the active ingredients in Michelia alba. During the extraction process, β-cyclodextrin is added as a complexing agent. β-cyclodextrin can form inclusion compounds with the active ingredients, increasing their solubility and stability in the solvent and further improving the extraction rate. In pulsed microwave-assisted extraction, the rapid vibration of microwaves promotes the intensification of molecular movement, accelerating the diffusion rate of active ingredients from cell debris into the solvent. This low-temperature synergistic extraction method not only improves the extraction efficiency of active ingredients but also avoids the destruction of thermosensitive components at high temperatures, resulting in a significant increase in the extraction rates of active ingredients such as total flavonoids and volatile oils.

[0031] The supercritical CO2 purification process is carried out in three stages. By precisely controlling the pressure, temperature, and CO2 flow rate, it is possible to selectively extract volatile components with different boiling points and polarities, effectively remove impurities, and improve the purity of the extract. In the first stage, at relatively low pressure and temperature, low-boiling-point aroma components are preferentially extracted; in the second and third stages, the pressure and temperature are gradually increased to ensure that high-boiling-point active ingredients can also be fully extracted. During molecular distillation refinement, under high vacuum and low-temperature conditions, the target active ingredients in the light-phase fraction can be quickly evaporated and separated, while the heavy-phase fraction returns to the supercritical CO2 purification stage for cyclic extraction. The total solvent recovery rate is ≥99.5%, which not only reduces solvent waste and production costs but also further improves the purity and quality of the extract. Brief Description of the Drawings

[0033] Figure 1 It is a process flow chart of the production process of the present invention. Detailed Embodiments

[0034] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of them. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts belong to the scope of protection of the present invention.

[0035] The following are specific embodiments:

[0036] Example 1

[0037] Pretreatment

[0038] Select 500 g of fresh Michelia alba flower petals without pests and diseases, place them in a container filled with deionized water containing 0.1% citric acid, turn on the ultrasonic cleaning equipment, and ultrasonically clean for 3 min. Then, transfer the petals to a centrifuge and centrifuge for dehydration at a speed of 3000 r / min for 5 min. The dehydrated petals are evenly spread on the tray of a vacuum freeze dryer, set the dryer temperature to -50°C and the pressure to 0.01 mbar, and perform the drying operation until the moisture content of the petals drops to 4.5%.

[0039] Gradient freezing and crushing

[0040] Put the dried petals into a screw conveyor pre-cooled with liquid nitrogen, start the cooling program, cool the temperature to -40°C at a rate of 5°C / min and maintain for 10 min. Then, continue to cool to -60°C at the same rate, maintain for 10 min, and then cool to -80°C again. Under the condition of -80°C, apply mechanical extrusion to the petals, and at the same time apply pulsed vibration at a frequency of 30 kHz, and the treatment time is 10 min. After the treatment, the cell wall fragmentation rate is detected to reach 95.2%.

[0041] Low-temperature co-extraction

[0042] Prepare a natural deep eutectic solvent according to the molar ratio of choline chloride to glycerol of 1:2. Mix the crushed petal powder with the natural deep eutectic solvent at a ratio of 1:8 in an extraction container, and add 0.05 wt% of β-cyclodextrin as a complexing agent. Place the extraction container in an environment of -15°C, turn on the pulsed microwave-assisted extraction equipment, set the microwave power to 300 W and the duty cycle to 1:3, and perform cyclic extraction 3 times, with each extraction time being 10 min. After the extraction is completed, transfer the mixed solution to a centrifuge and centrifuge at a speed of 12000 r / min for 15 min, collect the supernatant, and perform secondary extraction on the precipitate part.

[0043] Supercritical CO2 purification

[0044] Filter the extract through a 0.22 μm ceramic membrane to remove impurities. Then transfer the filtered extract to a supercritical CO2 extraction equipment for three-stage extraction:

[0045] The first stage: Set the pressure to 25 MPa, the temperature to 40°C, and the CO2 flow rate to 20 L / h, and extract for 30 min.

[0046] The second stage: Adjust the pressure to 30 MPa, the temperature to 45°C, and the CO2 flow rate to 24 L / h, and extract for 20 min.

[0047] Third stage: Further increase the pressure to 35 MPa, the temperature to 50 °C, and the CO2 flow rate to 28 L / h, and extract for 10 min. After the extraction is completed, collect the light-phase fraction rich in volatile components.

[0048] Molecular distillation refining

[0049] Transfer the light-phase fraction to a molecular distillation device, set the vacuum degree to 0.05 Pa, the temperature to 55 °C, and the scraper rotation speed to 300 rpm, and perform molecular distillation operation. Separate the heavy-phase fraction and return the heavy-phase fraction to step 4 for cyclic extraction.

[0050] Example 2

[0051] Pretreatment

[0052] Weigh 500 g of fresh white orchid petals, put them into deionized water containing 0.15% citric acid, and ultrasonically clean for 3.5 min. Then perform centrifugal dehydration under the same conditions as in Example 1. After dehydration, put the petals into a vacuum freeze dryer and dry them at -50 °C and 0.015 mbar until the moisture content reaches 4.8%.

[0053] Gradient freeze crushing

[0054] Place the dried petals on a spiral conveyor device pre-cooled with liquid nitrogen, cool them at a rate of 6 °C / min to -40 °C, maintain for 12 min, then cool to -60 °C and maintain for 12 min, and finally cool to -80 °C. Perform mechanical extrusion at -80 °C and apply pulsed vibration at 30 kHz for 11 min, and the cell wall breaking rate reaches 95.8%.

[0055] Low-temperature co-extraction

[0056] Prepare a natural deep eutectic solvent with a molar ratio of choline chloride to glycerol of 1:2.2, mix the crushed petal powder with this solvent at a ratio of 1:9, and add 0.06 wt% of β-cyclodextrin. Perform pulsed microwave-assisted extraction at -15 °C with the same parameters as in Example 1. After extraction, centrifuge for 18 min, collect the supernatant, and perform secondary extraction on the precipitate.

[0057] Supercritical CO2 purification

[0058] After filtering the extract, perform three-stage supercritical CO2 extraction:

[0059] First stage: The pressure is 26 MPa, the temperature is 41 °C, and the CO2 flow rate is 21 L / h, and extract for 30 min.

[0060] Second stage: The pressure is 32 MPa, the temperature is 46 °C, and the CO2 flow rate is 25 L / h, and extract for 20 min.

[0061] The third stage: pressure 36 MPa, temperature 52 °C, CO2 flow rate 29 L / h, extraction for 10 min. Collect the light-phase fraction.

[0062] Molecular distillation refining

[0063] Perform molecular distillation on the light-phase fraction at a vacuum degree of 0.06 Pa and a temperature of 58 °C, and recycle the heavy-phase fraction for extraction.

[0064] Example 3

[0065] Pretreatment

[0066] Take 500 g of fresh white orchid petals, ultrasonically clean them with deionized water containing 0.2% citric acid for 4 min, dehydrate by centrifugation, and then dry them in a vacuum freeze dryer at -50 °C and 0.02 mbar until the moisture content reaches 4.2%.

[0067] Gradient freeze crushing

[0068] Put the dried petals into a screw conveyor, cool them at a rate of 7 °C / min to -40 °C, maintain for 15 min, then cool to -60 °C and maintain for 15 min, and finally reach -80 °C. Perform mechanical extrusion at -80 °C and apply a 30 kHz pulsed vibration for 12 min, with a cell wall breakage rate of 96.1%.

[0069] Low-temperature co-extraction

[0070] Use a natural deep eutectic solvent with a molar ratio of choline chloride to glycerol of 1:2.5. Mix the petal powder with the solvent at a ratio of 1:10 and add 0.08 wt% of β-cyclodextrin. Perform pulsed microwave-assisted extraction at -15 °C, and after extraction, centrifuge for 20 min. The treatment method is the same as that in Example 1.

[0071] Supercritical CO2 purification

[0072] Filter the extract and then perform three-stage extraction:

[0073] The first stage: pressure 28 MPa, temperature 42 °C, CO2 flow rate 22 L / h, extraction for 30 min.

[0074] The second stage: pressure 35 MPa, temperature 48 °C, CO2 flow rate 26 L / h, extraction for 20 min.

[0075] The third stage: pressure 38 MPa, temperature 54 °C, CO2 flow rate 30 L / h, extraction for 10 min. Collect the light-phase fraction.

[0076] Molecular distillation refining

[0077] Perform molecular distillation on the light-phase fraction at a vacuum degree of 0.08 Pa and a temperature of 60 °C, and recycle the heavy-phase fraction.

[0078] Example 4

[0079] Pretreatment

[0080] Select 500 g of fresh white orchid flower petals, ultrasonically clean them with deionized water containing 0.12% citric acid for 3.2 min, and after centrifugal dehydration, dry them at -50°C and 0.012 mbar until the moisture content reaches 4.6%.

[0081] Gradient freezing and crushing

[0082] Put the dried petals into a screw conveyor pre-cooled with liquid nitrogen, cool them at a rate of 5.5°C / min to -40°C, maintain for 11 min, then cool to -60°C and maintain for 11 min, and finally reach -80°C. Perform mechanical extrusion at -80°C and apply pulsed vibration at 30 kHz for 10.5 min, and the cell wall breakage rate is 95.5%.

[0083] Low-temperature synergistic extraction

[0084] Prepare a natural deep eutectic solvent with a molar ratio of choline chloride to glycerol of 1:2.1, mix the petal powder with the solvent at a ratio of 1:8.5, and add 0.055 wt% of β-cyclodextrin. Perform pulsed microwave-assisted extraction at -15°C, and after extraction, centrifuge and separate for 16 min. The operation is the same as in Example 1.

[0085] Supercritical CO2 purification

[0086] After filtering the extract, perform three-stage extraction:

[0087] First stage: pressure 25.5 MPa, temperature 40.5°C, CO2 flow rate 20.5 L / h, extract for 30 min.

[0088] Second stage: pressure 31 MPa, temperature 45.5°C, CO2 flow rate 24.5 L / h, extract for 20 min.

[0089] Third stage: pressure 35.5 MPa, temperature 50.5°C, CO2 flow rate 28.5 L / h, extract for 10 min. Collect the light-phase fraction.

[0090] Molecular distillation refinement

[0091] Perform molecular distillation on the light-phase fraction at a vacuum degree of 0.055 Pa and a temperature of 56°C, and recycle the heavy-phase fraction for extraction.

[0092] Comparative Example 1

[0093] Extract the active ingredients in white orchid by the traditional steam distillation method.

[0094] Weigh 500 g of fresh white orchid petals and directly put them into the steam distillation device for 4 hours of distillation extraction operation.

[0095] Comparative Example 2

[0096] Omit the gradient freezing and crushing step during the extraction process.

[0097] Pretreatment: The same as in Example 1.

[0098] Direct extraction: Directly mix the pretreated petals with the natural deep eutectic solvent for low-temperature co-extraction, and other extraction conditions are the same as in Example 1. The subsequent supercritical CO2 purification and molecular distillation refinement steps are also the same as in Example 1.

[0099] Comparative Example 3

[0100] Do not perform the supercritical CO2 purification step.

[0101] Pretreatment and gradient freezing and crushing: The same as in Example 1.

[0102] Low-temperature co-extraction: The same as in Example 1.

[0103] Direct refinement: Directly perform molecular distillation refinement on the extract and omit the supercritical CO2 purification step.

[0104] Experiment:

[0105] Total flavonoid content test experiment

[0106] Test method: Refer to the aluminum salt colorimetric method in "Determination of Total Flavonoids in Health Foods" (GB5009.285-2022). Accurately weigh an appropriate amount of white orchid extract, dissolve it with methanol and make up the volume. Take a certain volume of the sample solution in a test tube, add sodium nitrite, aluminum nitrate and sodium hydroxide solutions in sequence, shake well and let it stand for color development. Measure the absorbance at a wavelength of 510 nm, and calculate the total flavonoid content according to the rutin standard curve;

[0107] Table 1: Test results of total flavonoid content

[0108]

[0109]

[0110] It can be seen from Table 1 that the extraction method of the present invention can effectively improve the extraction amount of total flavonoids, and the total flavonoid content in the comparative examples is relatively low, indicating that the traditional methods and different extraction methods have obvious effects on the extraction of total flavonoids.

[0111] DPPH free radical scavenging rate test experiment

[0112] Test method: Refer to "Determination of Antioxidant Activity of Plant Extracts - DPPH Free Radical Scavenging Method" (T / CPCIF0124 - 2021). Dissolve the Michelia alba extract with ethanol to prepare solutions of different concentrations. Take an appropriate amount of the solution and mix it with the DPPH ethanol solution. After shaking well, let it stand in the dark. Measure the absorbance at a wavelength of 517 nm and calculate the DPPH free radical scavenging rate. The calculation formula is: DPPH free radical scavenging rate (%) = [1 - (A sample - A sample blank) / A control] × 100%;

[0113] Table 2: Test Results of DPPH Free Radical Scavenging Rate

[0114]

[0115]

[0116] As can be seen from Table 2, the extraction method of the present invention can effectively retain the components with antioxidant activity, making the extract have strong antioxidant ability.

[0117] Test Experiment on Retention Rate of Aroma Components

[0118] Test method: Analyze by gas chromatography - mass spectrometry (GC - MS). Weigh the same mass of fresh Michelia alba petals and the obtained Michelia alba extract, and process them separately. After steam distillation of the fresh Michelia alba petals, collect the volatile oil, and directly inject the Michelia alba extract for analysis. Through GC - MS detection, compare the peak areas of the aroma components of the two, and calculate the retention rate of the aroma components. Retention rate of aroma components (%) = (total peak area of aroma components in the extract / total peak area of aroma components in fresh petals) × 100%;

[0119] Table 3: Test Results of Retention Rate of Aroma Components

[0120]

[0121]

[0122] As can be seen from Table 3, the extraction method of the present invention can well retain the aroma components of Michelia alba.

[0123] The preferred embodiments of the present invention disclosed above are only used to help illustrate the present invention. The preferred embodiments do not describe all the details in detail, nor limit the invention to the specific embodiments described. Obviously, many modifications and changes can be made according to the content of this specification.

Claims

1. A method for ultracold extraction of white jasmine, characterized in that: The following steps are involved: (1) Pretreatment: fresh white jasmine petals were ultrasonically cleaned in deionized water containing 0.1-0.2% citric acid for 3-4 minutes, centrifuged and then spread flat in a vacuum freeze dryer and dried at -50°C and 0.01-0.02 mbar to a moisture content of ≤5%; (2) Gradient freezing and crushing: Place the dried petals in a screw conveyor precooled with liquid nitrogen, cool them to -40°C at a rate of 5-7°C / min, maintain for 10-15 min, then cool them to -60°C, maintain for 10-15 min, then cool them to -80°C, and mechanically squeeze them to a cell wall crushing rate of ≥95%; (3) Low-temperature synergistic extraction: The crushed petal powder was mixed with the natural deep eutectic solvent in a ratio of 1:8-10, and pulsed microwave-assisted extraction was performed at -15°C. The extraction was repeated 3 times, each time for 10 min, to obtain an extract; (4) Supercritical CO2 purification: The extract was filtered through a 0.22 μm ceramic membrane and then subjected to supercritical fluid extraction to collect the light phase fraction rich in volatile components; (5) Molecular distillation refining: The light phase fraction is molecularly distilled at a vacuum degree of 0.05-0.08 Pa and a temperature of 55-60°C to separate the heavy phase fraction to obtain the white jasmine extract.

2. The method for ultracold extraction of white jasmine according to claim 1, characterized in that: In the step (2), while mechanical extrusion is being performed, pulse vibration is applied at a frequency of 30 kHz at -80°C for a treatment time of 10-12 minutes.

3. The method for ultracold extraction of white jasmine according to claim 1, characterized in that: The natural deep eutectic solvent in step (3) is a mixture of choline chloride and glycerol; The molar ratio of choline chloride to glycerol is 1:2-2.

5.

4. The method for ultracold extraction of white jasmine according to claim 3, characterized in that: In step (3), 0.05-0.08 wt % of β-cyclodextrin is added to the natural deep eutectic solvent as an inclusion agent during the extraction process.

5. The method for ultracold extraction of white jasmine according to claim 1, characterized in that: The pulse microwave-assisted extraction parameters in step (3) are microwave power of 300 W and duty cycle of 1:

3.

6. The method for ultracold extraction of white jasmine according to claim 5, characterized in that: After the pulse microwave-assisted extraction in step (3), the supernatant is collected by centrifugation, and the precipitate is subjected to secondary extraction; The centrifugal separation speed is 12000r / min and the time is 15-20min.

7. The method for ultracold extraction of white jasmine according to claim 1, characterized in that: The supercritical CO2 extraction in step (4) is carried out in three stages, including a first stage, a second stage, and a third stage.

8. The method for ultracold extraction of white jasmine according to claim 7, characterized in that: in, The first stage: pressure is 25-28MPa, temperature is 40-42℃, CO2 flow rate is 20-22L / h, The extraction time was 30 min; The second stage: pressure is 30-35MPa, temperature is 45-48℃, CO2 flow rate is 24-26L / h, and extraction time is 20min; The third stage: pressure is 35-38MPa, temperature is 50-54℃, CO2 flow rate is 28-30L / h, and extraction time is 10min.

9. The method for ultracold extraction of white jasmine according to claim 1, characterized in that: The heavy phase fraction after molecular distillation in step (5) is returned to step (4) for cyclic extraction, and the total solvent recovery rate is ≥99.5%.

10. The method for ultracold extraction of white jasmine according to claim 1, characterized in that: The white jasmine extract prepared by the method is used for preparing cosmetics with anti-oxidation and soothing effects, and the added amount is 0.1-1.5% (w / w).

Images