Green preparation method of plant essential oil

Abstract

The invention discloses a green preparation method of plant essential oil, aromatic plant essential oil is prepared by adopting a low-temperature pure physical preparation method, the whole process is low in temperature in the whole process, and oxidation of essential oil components and loss of low-boiling-point components cannot be caused; the whole process is a full-physical processing process, no organic solvent exists, and solvent residues and loss caused by solvent removal do not exist; the whole process is an all-essential oil preparation process, the polarity selection problem of CO2 and organic solvents is avoided, and the obtained essential oil is high in reduction degree.

Description

Technical Field

[0001] The invention relates to the field of plant extraction, and in particular to a green preparation method of plant essential oil. Background Art

[0002] Aromatic plants generally refer to plants whose leaves, flowers or whole plants contain aromatic essential oils, such as rose, mint, lavender, citrus, chrysanthemum, pine, pepper, etc., with different ingredients and flavors. People prepare essential oils and use them as pesticides, daily chemicals and food condiments.

[0003] The methods for obtaining natural plant essential oils generally include steam distillation, pressing, maceration, supercritical CO2 extraction, etc. Steam distillation is the most widely used method, but steam distillation requires heating the raw materials to 100°C, so that the essential oil evaporates with the water vapor and then condenses to separate the oil and water to obtain the plant essential oil. The method is simple and effective, but the high temperature of this process often leads to the loss of heat-sensitive components and the generation of unnecessary cooking smells; the pressing method is generally used for plants with rich essential oil content and the essential oil is mainly stored in the secretory cavity, such as citrus peel. The secretory cavity can be pierced under pressure to achieve oil-water residue separation, but it has little effect on the essential oil. This method is not practical for plants with low essential oil content or plants with high essential oil content but no oil secretion cavity; the maceration method is a method of soaking aromatic plants in oil, extracting the oil and then washing with alcohol to obtain essential oils, but the oil used in this method will affect the essential oils; supercritical carbon dioxide extraction is a method used in the preparation of essential oils in recent years. It has the advantages of low temperature (generally within 50°C), high efficiency (carbon dioxide in a supercritical fluid state has good solubility), and pollution-free (no carbon dioxide residue), but it also has the disadvantages of high equipment price, low yield of low boiling point components and high content of high melting point components. It is not very practical in the actual production of essential oils.

[0004] Essential oils are a collection of various secondary metabolites, including terpenes, fatty acids and esters, phenolic acids and flavonoids. Essential oils are mainly stored in glandular hairs, epidermal cells, secretory cavities or secretory ducts, oil cells and other storage organs in plants. The process of essential oil preparation is also the process of breaking these storage organs and releasing them. However, traditional methods have some problems such as high temperature, poor reproducibility and high cost. Summary of the invention

[0005] In view of the problems existing in the prior art, the present invention provides a green preparation method for plant essential oils, which adopts a low-temperature pure physical preparation method to prepare aromatic plant essential oils. The whole process is free of high temperature and organic solvents. It is a green, environmentally friendly, and high-flavor restoration essential oil preparation process.

[0006] A green preparation method of plant essential oil, using aromatic plants as raw materials, comprises the following steps:

[0007] (1) adding water to fresh raw materials to obtain slurry; or, crushing dry raw materials and soaking them in water to obtain liquid;

[0008] (2) adding water to the slurry or liquid, grinding at a temperature greater than 0° C. and less than or equal to 20° C. until the particle size is less than or equal to 500 meshes, to obtain a grinding liquid;

[0009] (3) centrifuging the grinding liquid at 8000 rpm to 12000 rpm and at a temperature greater than 0° C. and less than or equal to 20° C. to separate and obtain a first liquid A1 and a first solid B1;

[0010] (4) adding water to the first solid B1, and ball-milling the solid at a temperature greater than 0° C. and less than or equal to 20° C. until the particle size is less than or equal to 3000 mesh, to obtain a ball-milling liquid;

[0011] (5) centrifuging the ball milling liquid at 8000 rpm-12000 rpm and a temperature greater than 0° C. and less than or equal to 20° C. to separate and obtain a second liquid A2 and a second solid B2;

[0012] (6) adding water to the second solid B2, stirring for 3 min-10 min, and then centrifuging at 8000 rpm-12000 rpm and a temperature greater than 0° C. and less than or equal to 20° C. to separate and obtain a third liquid A3 and a third solid B3;

[0013] (7) The first liquid A1, the second liquid A2 and the third liquid A3 are combined to obtain an extract, an inorganic salt is added to the extract, and the extract is slowly stirred at a speed of 30 to 240 rpm at a temperature greater than 0° C. and less than or equal to 20° C. The extract is allowed to stand for oil and water to separate the essential oil and water, thereby obtaining the plant essential oil.

[0014] The present invention adopts the above-mentioned specific steps and specific processes to gradually extract and separate at low temperature in multiple steps, so as to ensure that the plant essential oil with no organic solvent residue, green and environmental protection and high flavor restoration degree is finally obtained.

[0015] In order to achieve better technical effects, the following optimization is performed:

[0016] In step (1), the weight ratio of the fresh raw material to water is 1:1-3. The slurry has a fineness of at least 16 mesh; it is further preferably processed into a slurry with a smaller particle size, such as 50 mesh. The fresh raw material can be selected from fresh aromatic plants, such as fresh bamboo leaves. The weight ratio of the dry raw material to water is 1:1-3. The dry raw material is crushed to at least 200 mesh; it is further preferably crushed into a material with a smaller particle size, such as 300 mesh. The soaking time is preferably to completely soak the dry raw material, for example, it can be soaked for 8 hours to 10 hours. The dry raw material can be selected from dry aromatic plants, such as dry lavender.

[0017] In step (2), the weight ratio of the slurry or liquid to water is 1:0.5-5. The grinding is performed by a colloid mill. More preferably, the grinding is performed by a colloid mill for multiple cycles (most preferably more than three times).

[0018] In step (4), the weight ratio of the first solid B1 to water is 1:0.5-5. The ball milling uses zirconium oxide ball milling beads to avoid metal residue. Further preferably, water is added to the first solid B1, and the ball milling is performed at a temperature greater than 0°C and less than or equal to 20°C until the particle size is less than or equal to 5000 mesh to obtain a ball milling liquid.

[0019] In step (6), the weight ratio of the second solid B2 to water is 1:0.5-5. The stirring may be performed using a beater.

[0020] In step (7), the amount of the inorganic salt added is 3%-8% of the weight of the extract, preferably 5%. The inorganic salt is selected from sodium chloride, potassium chloride, etc.

[0021] The slow stirring time is generally 12 hours to 48 hours. The slow stirring can be magnetic stirring.

[0022] The water separated after the oil-water separation can be circulated and used for extracting essential oils from the same plant.

[0023] In step (7), at a separation temperature greater than 0°C and less than or equal to 20°C and a stirring rate of 30rpm-240rpm, a certain amount of essential oil with rich component types can be obtained. More preferably, at a separation temperature greater than 0°C and less than or equal to 10°C and a stirring rate of 30rpm-90rpm, essential oil with rich component types can be obtained with a high yield. Even more preferably, at a separation temperature greater than 0°C and less than or equal to 8°C (most preferably 2°C-4°C) and a stirring rate of 30rpm-60rpm, essential oil with rich component types can be obtained with a high yield.

[0024] The operating temperatures of grinding, ball milling, centrifugation and the like are all controlled below 20° C. and above 0° C., thereby avoiding the loss of essential oil components during the operation.

[0025] In the present invention, the water is preferably purified water.

[0026] Compared with the prior art, the present invention has the following advantages:

[0027] The whole process is carried out at a low temperature, which will not cause the oxidation of essential oil components and the loss of low-boiling point components.

[0028] The entire process is a fully physical processing process, without any organic solvents, and there is no solvent residue or loss caused by desolventization.

[0029] The entire process is a full essential oil preparation process, without the problem of polarity selection of CO2 and organic solvents, and the obtained essential oil has a high reduction degree.

[0030] The extraction solvent of the method of the present invention is water, and the water separated after oil-water separation can be recycled and used for essential oil extraction of the same plant, without high-temperature thermal energy, low energy consumption, low extraction agent cost, and suitable for large-scale industrial use. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 The present invention is a process flow chart of the green preparation method of plant essential oil.

[0032] Figure 2 GCMS chromatograms of Indocalamus leaf essential oil obtained by four methods.

[0033] Figure 3 This is a comparison chart of the component quantities of Indocalamus leaf essential oil obtained by four methods.

[0034] Figure 4 The relative contents of the essential oil components of Indocalamus leaf obtained by four methods.

[0035] Figure 5 This is the particle size distribution diagram of the material after ball milling in the present invention.

[0036] Figure 6 This is a particle size distribution diagram of the liquid solute after the ball-milled material is centrifuged in the present invention.

[0037] Figure 5 , Figure 6In the table, Results means results, Diam. means diameter, Intensity means intensity, Width means width, Z-Average means the average particle size obtained by intensity distribution, PdI means aggregation index, Intercept means the intercept of the particle size distribution curve on the horizontal axis, Result quality means the quality of the result, Good means good, peak means peak, Size Distribution by Intensity means size distribution by intensity, Size means size, Record means record, and Refer to quality report means reference to quality report.

[0038] Figure 7 This is a graph showing the relationship between material size and essential oil yield (based on dry material) obtained using different methods.

[0039] Figure 8 This is a graph showing the effect of processing temperature on essential oil yield.

[0040] Fig. 9 This is a graph showing the effect of stirring rate on essential oil yield.

[0041] Fig.10 This is a graph showing the effects of processing temperature and stirring rate on the yield of orange peel essential oil.

[0042] Fig.11 The following is a comparison chart of the components of lavender essential oil obtained by three methods (top: water extraction; middle: supercritical; bottom: the present invention). DETAILED DESCRIPTION

[0043] The present invention is further described in detail below in conjunction with the accompanying drawings and specific embodiments so that those skilled in the art can better understand the technical solutions of the present invention.

[0044] Embodiment 1:

[0045] (1) 10 kg of fresh Indocalamus japonica leaves were collected, washed, added with 10 kg of purified water, and beaten with a pulper to obtain a slurry with a fineness of 16 meshes;

[0046] (2) Add 10 kg of pure water to the 20 kg slurry, put it into the colloid mill, control the temperature at 15°C-20°C, and grind it in cycles at three levels of grinding disc gap: high, medium and low. Grind it three times in total, each time for 30 minutes, to obtain a grinding liquid with a fineness of 500 mesh;

[0047] (3) adding the grinding liquid into a low-temperature centrifuge, centrifuging at 10,000 rpm and 10° C. for 5 minutes to separate and obtain a first liquid A1 and 8.5 kg of a first solid B1;

[0048] (4) 8.5 kg of the first solid B1 was added to 7 kg of pure water, stirred and mixed, and then added to a low-temperature ball mill. Zirconia ball milling beads were used for ball milling at a temperature of 10° C. for 45 minutes to obtain a ball milling liquid with a fineness of at least 3000 mesh;

[0049] (5) Add the ball-milled liquid to a low-temperature centrifuge and centrifuge at 10,000 rpm and 10° C. to obtain a second liquid A2 and 7.5 kg of a second solid B2;

[0050] (6) 7.5 kg of the second solid B2 was added with 10 kg of pure water, and the mixture was repeatedly stirred for 3 min using a blender, and then centrifuged using a low-temperature centrifuge at 10,000 rpm and 10° C. to obtain a third liquid A3 and a third solid B3;

[0051] (7) The first liquid A1, the second liquid A2 and the third liquid A3 were combined to obtain 40 kg of extract, which was added to a flat-bottomed narrow-mouthed separatory bottle, and 2 kg of sodium chloride was added. The mixture was slowly stirred at a speed of 45 r / min at a temperature of 2° C. for 48 hours, and the essential oil and water were separated after standing for oil-water separation to obtain 26.14 g of Indocalamus leaf essential oil. The essential oil yield was 2.614 mg / g (based on fresh Indocalamus leaf), and the dry material yield was 6.53 mg / g according to the moisture content of the raw material.

[0052] Comparative Example 1: Steam distillation

[0053] Weigh 10 kg of fresh Indocalamus japonicus leaves, wash them, add 10 kg of pure water, heat to boiling, and extract by condensation reflux to obtain 29.1 g of Indocalamus japonicus leaf water-extracted essential oil, with an essential oil yield of 2.91 mg / g (based on fresh Indocalamus japonicus leaves).

[0054] Comparative Example 2: Supercritical CO2 Extraction

[0055] 10 kg of fresh Indocalamus japonicus leaves were weighed and extracted with supercritical CO2 fluid at 35°C to separate 162.74 g of Indocalamus japonicus leaf supercritical extraction essential oil. The yield of essential oil was 16.274 mg / g (based on fresh Indocalamus japonicus leaves).

[0056] Comparative Example 3: Dynamic Headspace Method

[0057] The dynamic headspace method is to continuously blow nitrogen through the sample, carry the volatile essential oil components to the adsorption tube through nitrogen, and be adsorbed by the adsorption material, and concentrate them at -100℃, and then quickly heat and inject them for GCMS analysis. This method has a high recognition rate for plant aromatic components and a good composition reduction degree. The essential oil obtained by this method was used to detect the composition of the essential oil in the leaves of Indocalamus japonica.

[0058] Weigh 4 g of fresh Indocalamus japonicus leaves, continuously blow nitrogen through the Indocalamus japonicus leaf sample, carry the volatile essential oil components to the adsorption tube through the nitrogen and be adsorbed by the adsorption material (Tetax material, the component is 2,6-dibenzofuran porous polymer resin), and concentrate it at -100°C to obtain the dynamic headspace essential oil of Indocalamus japonicus leaves.

[0059] Comparison of the essential oil obtained by the present invention with other methods:

[0060] Taking Indocalamus japonica leaves as an example, steam distillation, supercritical extraction, dynamic headspace extraction and the method of the present invention were used to extract essential oil and compared.

[0061] Take 10 μL of the essential oil of Indocalamus leaf in Example 1, 10 μL of the essential oil of Indocalamus leaf water extraction in Comparative Example 1, and 10 μL of the essential oil of Indocalamus leaf supercritical extraction in Comparative Example 2, respectively, add 2 mL of n-hexane for oscillation and dissolution, pass through an organic filter membrane, and directly inject the essential oil of Indocalamus leaf dynamic headspace adsorption in Comparative Example 3, and analyze it by GCMS. The results are shown in Table 1. Figure 2 , Figure 3 and Figure 4 .

[0062] GCMS conditions: chromatographic column DB-HeavyWAX (30m×0.25mm, 0.25μm), carrier gas (high purity helium) flow rate 1.0mL / min, injection port temperature 250℃, heating program: initial temperature 40℃, hold for 5min, then heat to 280℃ at a rate of 4℃ / min, hold for 5min. Mass spectrometer interface temperature 280℃, ion source temperature 230℃, mass scan range m / z 35-550, qualitative library NIST2020.

[0063] The indocalamus leaf essential oil components obtained by the method of the present invention are compared with conventional water-extracted essential oil components, dynamic headspace essential oil components and supercritical extraction essential oil components. It can be found that: the indocalamus leaf essential oil obtained by the method of the present invention is closest to the essential oil components obtained by the dynamic headspace method, the types are basically the same, and the low-boiling point and high-boiling point components are relatively uniform; the extremely low-boiling point components in the water-extracted essential oil obtained by the steam distillation method are also lost in large quantities, and the high-boiling point components are basically absent; the essential oil components obtained by supercritical carbon dioxide have serious losses in low-boiling point components, which are mainly concentrated in high-boiling point components.

[0064] from Figure 3 It can be seen that the composition of the essential oil obtained by the method of the present invention is similar to that of the essential oil obtained by the dynamic headspace method, in which phenols and alkanes are more abundant than those by the dynamic headspace method, which is related to the extraction principle. The dynamic headspace is captured by nitrogen purge, and phenols and alkanes are difficult to be blown out at low temperatures, so there are fewer related components. Figure 4It can also be seen from the relative content graph that the composition of essential oils obtained by the method of the present invention is basically consistent with that by the dynamic headspace method. The contents of alkane substances that contribute less to flavor are relatively low in both methods; while the contents of alkane substances that contribute less to flavor in the essential oils obtained by steam distillation and supercritical extraction are significantly higher than those in the method of the present invention. It can be seen that the plant essential oil obtained by the method of the present invention has the highest degree of component reduction compared with the essential oils obtained by steam distillation and supercritical extraction.

[0065] Table 1 Comparison of essential oil components obtained by four different methods

[0066]

[0067]

[0068]

[0069] Example 2: Effect of crushed particle size on essential oil extraction rate

[0070] The present invention finds that the grinding degree of the material is closely related to the extraction efficiency of the essential oil. In Example 1, after the fresh indocalamus leaves are pulped, colloid milled and ball milled, the particle size distribution of the ball milling liquid material is shown in FIG. Figure 5 ,from Figure 5 It can be seen that after the beating, colloid milling and ball milling of the present invention, the material reaches a fineness of 5000 mesh (about 2.6 μm), the average particle size of the material is 0.3011 μm, and the distribution range is 20 nm-3 μm. At this time, the yield of essential oil becomes high. The material is centrifuged and the second liquid A2 contains a small amount of impurities and essential oil components. The particle size distribution of the solute in the second liquid A2 is shown in FIG. Figure 6 , the average particle size of the solute becomes 3.054nm, the distribution range is 1nm-3μm, and it is mainly distributed in the range of 1nm-3nm and 10nm-40nm.

[0071] The slurry obtained by the operation in step (1) of Example 1 was added to a low-temperature centrifuge and centrifuged at 10000 rpm and 10°C to obtain a liquid and a solid. The liquid was added to a flat-bottomed narrow-mouthed separation bottle, and 2 kg of sodium chloride was added. The mixture was slowly stirred at a speed of 45 r / min at a temperature of 2°C for 48 hours. After standing for oil and water separation, 0.04 g of Indocalamus leaf essential oil was obtained. The essential oil yield based on fresh raw material was 0.004 mg / g (the yield converted to dry raw material was 0.01 mg / g), recorded as: 1-shear only.

[0072] The first liquid A1 obtained by the operations in steps (1), (2) and (3) of Example 1 was added to a flat-bottomed narrow-mouthed separatory flask, and 2 kg of sodium chloride was added. The mixture was slowly stirred at a speed of 45 r / min at a temperature of 2° C. for 48 hours. After standing for oil-water separation, 5.21 g of Indocalamus leaf essential oil was obtained. The essential oil yield based on fresh raw material was 0.521 mg / g (the yield converted to dry raw material was 1.3 mg / g), recorded as: 2-colloid mill.

[0073] Except that the ball milling time in step (4) of Example 1 was replaced with 5 min to obtain a ball milling solution with an average particle size of 4.5 μm, the remaining operations were the same as in Example 1 to obtain 7.22 g of indocalamus leaf essential oil, with an essential oil yield of 0.722 mg / g based on fresh raw material (1.81 mg / g based on dry raw material), recorded as: 3-ball milling 1.

[0074] Except that the ball milling time in step (4) of Example 1 was replaced with 10 min to obtain a ball milling solution with an average particle size of 0.9 μm, the remaining operations were the same as in Example 1 to obtain 12.48 g of indocalamus leaf essential oil. The essential oil yield based on fresh raw material was 1.248 mg / g (the yield converted to dry raw material was 3.12 mg / g), recorded as: 4-ball milling 2.

[0075] According to the operation of Example 1, a ball milling liquid with an average particle size of 0.3 μm was obtained, and 26.14 g of Indocalamus leaf essential oil was obtained. The essential oil yield based on fresh raw materials was 2.614 mg / g (converted to a dry raw material yield of 6.53 mg / g), recorded as: 5-ball mill 3.

[0076] The material size obtained by different grinding processes and the essential oil yield can be seen in Figure 7 ,from Figure 7 It can be seen that the essential oil yield is significantly positively correlated with the fineness of the material. The fineness of the material obtained under the process conditions of the present invention can obtain a relatively high essential oil yield while ensuring a high degree of reduction of the essential oil components.

[0077] Embodiment 3:

[0078] (1) Weigh 10 kg of dried lavender, crush it to a fineness of 200 mesh using a pulverizer, add 20 kg of purified water, and soak for 8 hours to obtain a feed liquid;

[0079] (2) Add 30 kg of pure water to the 30 kg of soaked liquid, grind with a colloid mill, control the temperature at 10°C-15°C, and grind in cycles at three levels of grinding disc clearance: high, medium and low. Grind three times in total, each time for 30 minutes, to obtain a grinding liquid with a fineness of 500 mesh;

[0080] (3) adding the grinding liquid into a low-temperature centrifuge, centrifuging at 12000 rpm and 10° C. for 5 minutes to separate and obtain a first liquid A1 and 15 kg of a first solid B1;

[0081] (4) Add 15 kg of pure water to 15 kg of the first solid B1, stir and mix, then add to a low-temperature ball mill, use a zirconium oxide mill, and ball mill for 3 times at 10°C, each time for 30 minutes, until a ball milling liquid with a fineness of 3000 mesh is obtained;

[0082] (5) Add the ball milling liquid to a low-temperature centrifuge and centrifuge at 12,000 rpm and 10° C. to obtain a second liquid A2 and 15 kg of a second solid B2;

[0083] (6) 15 kg of the second solid B2 was added with 10 kg of pure water, and the mixture was repeatedly stirred for 3 min using a blender, and then centrifuged using a low-temperature centrifuge at 12,000 rpm and 10° C. to obtain a third liquid A3 and a third solid B3;

[0084] (7) The first liquid A1, the second liquid A2 and the third liquid A3 were combined to obtain 72 kg of extract, which was added to a flat-bottomed narrow-mouthed separatory bottle, and 3.6 kg of sodium chloride was added. The mixture was slowly stirred at a speed of 30 r / min at a temperature of 5° C. for 48 hours. The essential oil and water were separated after standing to separate the oil and water layers, and 70.6 g of lavender essential oil was obtained, with an essential oil yield of 7.06 mg / g.

[0085] Embodiment 4:

[0086] According to the method of Example 3, the separation temperature and stirring rate after adding 3.6 kg of sodium chloride in step (7) were adjusted, and multiple groups of experiments were carried out. The results are as follows: Figure 8 (Stirring rate is stable at 30r / min, adjust temperature) and Fig. 9 (At 4°C, adjust the stirring speed).

[0087] According to the method of Example 1, 10 kg of fresh Indocalamus japonica leaves were replaced with 10 kg of fresh orange peels, and the separation temperature and stirring rate after adding 2 kg of sodium chloride in step (7) were adjusted. Multiple groups of experiments were carried out, and the results were as follows: Fig.10 (The stirring rate of different temperature curves is stable at 30r / min, and the temperature of different stirring rate curves is all at 4°C).

[0088] The study found that with the increase of the treatment temperature (i.e., separation temperature), the yield of essential oil is reduced, especially after being greater than 4°C, the yield reduction speed becomes faster, but the present invention uses the same process to extract essential oils from other materials (such as Indocalamus leaf), and the Indocalamus leaf material can also achieve good results (high yield) at 8°C, which is mainly related to the composition of the essential oil components. With the increase of the stirring rate, under the stirring of the blade, the suspended essential oil particles will gather and rise, which is beneficial to the separation of the essential oil, but with the increase of the stirring rate, emulsification will occur, and the yield will also decrease, especially after being greater than 60r / min (rpm), if the stirring rate exceeds 240rpm, it is basically impossible to obtain essential oil. Comprehensive analysis shows that the method of the present invention can obtain a certain amount of essential oil with rich components at a separation temperature greater than 0°C and less than or equal to 20°C and a stirring rate of 30rpm-240rpm. Preferably, at a separation temperature greater than 0°C and less than or equal to 10°C and a stirring rate of 30rpm-90rpm, essential oil with rich components and high yield can be obtained. It is further preferred that at a separation temperature greater than 0°C and less than or equal to 8°C and a stirring rate of 30rpm-60rpm, essential oil with rich components and high yield can be obtained. Most preferably, at a separation temperature of 2°C-4°C and a stirring rate of 30rpm-60rpm, essential oil with rich components and higher yield can be obtained.

[0089] Comparative Example 4: Steam distillation

[0090] Weigh 10 kg of dried lavender, crush it to 200 mesh fineness with a grinder, add 20 kg of pure water, soak for 8 hours, heat to boiling state, condense and reflux to extract, and obtain 10.31 g of lavender water-extracted essential oil. The essential oil yield is 1.031 mg / g.

[0091] Comparative Example 5: Supercritical CO2 Extraction

[0092] Weigh 10 kg of dried lavender, crush it to 200 mesh fineness with a pulverizer, extract it with supercritical CO2 fluid at 35°C, and separate 46.95 g of lavender supercritical extraction essential oil. The essential oil yield is 4.70 mg / g.

[0093] Take 10 μmL of lavender essential oil from Example 3, 10 μmL of lavender water-extracted essential oil from Comparative Example 4, and 10 μmL of lavender supercritically extracted essential oil from Comparative Example 5, add 2 mL of n-hexane to shake and dissolve, pass through an organic filter membrane, and analyze by GCMS. The lavender essential oil extracted by the method of the present invention (abbreviated as: the present invention) is compared with lavender water-extracted essential oil (abbreviated as: water extraction) and lavender supercritically extracted essential oil (abbreviated as: supercritical), and the results are shown in Tables 2 and 3. Fig.11 ;

[0094] Table 2 Comparison of the main components of lavender essential oil obtained by three methods (content ≥ 0.1%)

[0095]

[0096] The above table lists the main essential oil components with a relative content of more than 0.1%. From Table 2, the main component comparison and chromatogram of the three essential oils Fig.11 It can be seen that 24 main components of lavender water-extracted essential oil were identified, mainly concentrated in the front section of chromatographic separation, mainly linalool and lavandin acetate, accounting for 36.17% and 12.43% of the total components; 16 main components of lavender supercritical extraction essential oil were identified, distributed in the front, middle and back sections of the chromatography, and the main components were linalool, fennel and lavandin acetate, accounting for 21.03%, 39.41% and 13.63% of the total components respectively; 24 main components were identified in the essential oil obtained by the present invention, the number was the same as that of the water-extracted essential oil, but distributed in the front, middle and back sections of the chromatographic separation, indicating that the molecular weight of each section is relatively uniform, and the content of linalool, fennel and lavandin acetate is more than 10%, accounting for 15.86%, 23.11% and 13.73% of the total components respectively. It can be seen that the reduction degree of the essential oil obtained by the method of the present invention is the highest.

[0097] The change of parameters in the preparation method of the present invention, such as the change of the amount of water added, does not affect the preparation of essential oils, so any combination of parameters in the preparation method of the present invention can achieve the preparation of essential oils. They will not be listed one by one here.

Claims

1. A green preparation method of plant essential oil, characterized in that: The method uses aromatic plants as raw materials and includes the following steps: (1) adding water to fresh raw materials to obtain slurry; or, crushing dry raw materials and soaking them in water to obtain liquid; (2) adding water to the slurry or liquid, grinding at a temperature greater than 0° C. and less than or equal to 20° C. until the particle size is less than or equal to 500 meshes, to obtain a grinding liquid; (3) centrifuging the grinding liquid at 8000 rpm-12000 rpm and at a temperature greater than 0° C. and less than or equal to 20° C. to separate and obtain a first liquid A1 and a first solid B1; (4) adding water to the first solid B1, and ball-milling the solid at a temperature greater than 0° C. and less than or equal to 20° C. until the particle size is less than or equal to 3000 mesh, to obtain a ball-milling liquid; (5) centrifuging the ball milling liquid at 8000 rpm-12000 rpm and a temperature greater than 0° C. and less than or equal to 20° C. to separate and obtain a second liquid A2 and a second solid B2; (6) adding water to the second solid B2, stirring for 3 min-10 min, and then centrifuging at 8000 rpm-12000 rpm and a temperature greater than 0° C. and less than or equal to 20° C. to separate and obtain a third liquid A3 and a third solid B3; (7) The first liquid A1, the second liquid A2 and the third liquid A3 are combined to obtain an extract, an inorganic salt is added to the extract, and the extract is slowly stirred at a speed of 30 r / min-240 r / min under a temperature greater than 0° C. and less than or equal to 20° C. The essential oil and water are separated after standing to obtain the plant essential oil.

2. The green preparation method of plant essential oil according to claim 1, characterized in that: In step (1), the weight ratio of the fresh raw material to water is 1:1-3; or, the weight ratio of the dry raw material to water is 1:1-3.

3. The green preparation method of plant essential oil according to claim 1, characterized in that: The slurry has a fineness of at least 16 mesh; alternatively, the dry raw material is crushed to at least 200 mesh.

4. The green preparation method of plant essential oil according to claim 1, characterized in that: In step (2), the weight ratio of the slurry or liquid to water is 1:0.5-5.

5. The green preparation method of plant essential oil according to claim 1, characterized in that: In step (2), the grinding is performed by colloid milling for multiple cycles.

6. The green preparation method of plant essential oil according to claim 1, characterized in that: In step (4), the weight ratio of the first solid B1 to water is 1:0.5-5.

7. The green preparation method of plant essential oil according to claim 1, characterized in that: In step (4), the ball milling uses zirconium oxide ball milling beads.

8. The green preparation method of plant essential oil according to claim 1, characterized in that: In step (6), the weight ratio of the second solid B2 to water is 1:0.5-5.

9. The green preparation method of plant essential oil according to claim 1, characterized in that: In step (7), the amount of the inorganic salt added is 3%-8% of the weight of the extract; the inorganic salt is selected from sodium chloride and potassium chloride.

10. The green preparation method of plant essential oil according to claim 1, characterized in that: The slow stirring time is 12 hours to 48 hours.

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