A method for distilling volatile oil from Forsythia suspensa

Abstract

This invention relates to the field of separation and purification, and particularly to a distillation method for Forsythia suspensa volatile oil, comprising the following steps: Step (1) Crush dried Forsythia suspensa fruit and mix it with water at a mass ratio of 1:3-5, grinding until the particle size D90≤50μm to obtain Forsythia suspensa slurry; Step (2) Add porous medium A particles with a particle size of 0.5-1mm and water-absorbing medium B to the Forsythia suspensa slurry obtained in Step (2), stir and mix for 20-40min to obtain a cake; Step (3) Mix the cake with moistened porous medium C particles with a particle size of 1-3cm, then load it into a distillation kettle for distillation, collect the distillate and separate to obtain Forsythia suspensa volatile oil. This scheme optimizes the distillation process, improves distillation efficiency, and solves the clogging problem caused by excessively fine grinding of raw materials, thereby meeting the industrial production demand for efficient and stable extraction of Forsythia suspensa volatile oil.

Description

Technical Field

[0001] This invention relates to the field of separation and purification, and more particularly to a distillation method for Forsythia suspensa volatile oil. Background Technology

[0002] With the continuous development of extraction technology for volatile oils of traditional Chinese medicine, Forsythia suspensa volatile oil has become a research hotspot due to its significant pharmacological activity. However, among existing technologies, distillation extraction of Forsythia suspensa volatile oil is the most efficient, commonly used, and mature method, but it still has certain shortcomings in terms of efficiency, ease of operation, and adaptability to raw material processing, which affect its industrial application and production benefits: if the Forsythia suspensa fruit is not ground sufficiently, the distillation efficiency is low; if it is ground too finely, it is easy to clog the equipment.

[0003] A search revealed a processing method for Forsythia suspensa and the processed Forsythia suspensa, published on November 10, 2020, with publication number CN108379352B. This patent provides a method for extracting volatile oil from Forsythia suspensa through steps such as cold preservation, steam blanching, initial drying, and re-drying, effectively controlling the content of volatile oil and other effective components in Forsythia suspensa. However, this technical solution has high requirements for the pretreatment of raw materials, especially requiring multiple temperature control steps, resulting in a complex and time-consuming process.

[0004] A search revealed a method for preparing the Mongolian medicine Sulongga-4, published on November 17, 2020, with publication number CN108114149B. This patent uses steam distillation to extract volatile oil from Forsythia suspensa and combines it with other medicinal extracts to form granules. While this method effectively preserves the active ingredients of the volatile oil, its distillation process is relatively traditional and lacks clear guidance on controlling the particle size of the raw materials. This can easily lead to clogging of the distillation equipment due to excessively fine grinding of the raw materials, thus affecting production continuity and efficiency. Summary of the Invention

[0005] To overcome the above deficiencies, this invention provides a distillation method for Forsythia suspensa volatile oil, which aims to optimize the distillation process, improve distillation efficiency, and solve the clogging problem caused by excessively fine grinding of raw materials, thereby meeting the industrial production demand for efficient and stable extraction of Forsythia suspensa volatile oil.

[0006] To achieve the above objectives, the present invention adopts the following technical solution:

[0007] A method for distilling Forsythia suspensa volatile oil includes the following steps:

[0008] Step (1) After pulverizing the dried forsythia fruit, mix it with water at a mass ratio of 1:3-5 and grind it until the particle size D90≤50μm to obtain forsythia slurry;

[0009] Step (2) Add porous media A particles with a particle size of 0.5-1mm to the Forsythia slurry obtained in step (2), ball mill and stir for 10-30 minutes, vacuum stir for 20-40 minutes, then add water-absorbing media B to the slurry and stir and mix for 20-40 minutes to obtain a cake; the amount of porous media A added is 5-10 parts by weight of the dry matter of Forsythia; the amount of water-absorbing media B added is 10-15 parts by weight of the dry matter of Forsythia.

[0010] Step (3) Wetted porous medium C with a particle size of 1-3 cm is mixed into the cake, and then it is loaded into a distillation kettle for distillation. The distillate is collected and separated by extraction or fractionation to obtain the volatile oil of Forsythia suspensa. The amount of porous medium C added is 15-20 parts by mass of the dry matter of Forsythia suspensa. The distillate is extracted by conventional extraction or fractionation.

[0011] The overall design concept of this scheme is to minimize the particle size of Forsythia fruit to improve distillation efficiency. However, in conventional techniques, reducing the particle size of Forsythia fruit easily leads to equipment blockage during distillation, causing production stoppages. In this scheme, porous medium A is used to adsorb tiny Forsythia fruit particles during distillation. Vacuum stirring allows some of these particles to enter the pores of porous medium A. Since porous medium A is hydrophilic, the deeper parts of the pores are filled with water, meaning most of the Forsythia fruit particles entering the pores are on the outer side. During heating and distillation, the water in the pores evaporates, carrying away the volatile substances from the Forsythia fruit particles. Secondly, water-absorbing medium B is mainly used to adsorb water from the remaining slurry and to disperse the slurry containing the adsorbed Forsythia fruit particles as much as possible, increasing the steam contact area. Porous medium C acts as a framework, and since it contains wetting particles, it provides more contact surface during distillation and serves as a secondary steam source.

[0012] Secondly, this scheme controls the temperature, pressure, and steam conditions during the distillation process and optimizes the distillation efficiency, so that the volatile oil of Forsythia can be distilled out stably and with high quality.

[0013] Preferably, the porous medium A is diatomaceous earth or expanded perlite with a pore size of 5-50 μm.

[0014] This pore size design allows for better adsorption of Forsythia suspensa particles, or even embedding them within porous medium A.

[0015] Preferably, the water-absorbing medium B is bentonite or attapulgite with a particle size of 2-3 mm.

[0016] Preferably, the porous medium C is lightweight shale ceramsite or volcanic rock particles with an open porosity of ≥30%.

[0017] Preferably, the particle size of the crushed Forsythia fruit granules in step (1) is 1-5 mm.

[0018] To save costs, the porous media A, water-absorbing media B, and porous media C selected in this scheme are all recyclable materials. The recycling method is to regenerate them by calcining at 150-250℃ for 1-2 hours, and then reusing them after screening.

[0019] Preferably, the vacuum degree in the vacuum stirring process is 0.05-0.06 MPa.

[0020] Preferably, the distillation process in the distillation vessel is as follows: steam at a temperature of 110-140℃ is introduced, the pressure inside the distillation vessel is 0.2-0.5MPa, and it is maintained for 10-15 minutes. Then, the pressure is reduced to 0.1-0.2MPa, and the distillation is carried out for 3-5 hours. Finally, the pressure is reduced to 0.06-0.08MPa and maintained for 30-60 minutes.

[0021] Preferably, the wetting process of the porous medium C after wetting involves immersion in water followed by draining.

[0022] This method consists of three stages of pressure swing distillation: a high-pressure stage of 0.2-0.5 MPa for 10-15 minutes to break through the cell wall barrier and increase the initial release rate of volatile oils; a medium-pressure stage of 0.1-0.2 MPa for 3-5 hours to maintain steady-state distillation; and a low-pressure stage of 0.06-0.08 MPa to extract high-boiling-point sesquiterpenes (such as β-caryophyllene) and improve the yield.

[0023] The present invention has the following beneficial effects:

[0024] 1. Based on the traditional solution, by introducing porous media A, porous media C and water-absorbing media B, an adsorption-dispersion-framework structure is constructed, which overcomes the problem of clogging of distillation equipment due to excessively fine grinding of raw materials, thereby affecting the continuity and efficiency of production.

[0025] 2. Based on the adsorption-dispersion-skeleton structure, the distillation process was optimized, improving distillation efficiency and recovery rate. Detailed Implementation

[0026] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0027] Example 1

[0028] A method for distilling Forsythia suspensa volatile oil includes the following steps:

[0029] Step (1) After crushing the dried forsythia fruit into particles with a diameter of 2 mm, mix it with water at a mass ratio of 1:5 and grind it until the particle size D90 is 43 μm to obtain forsythia slurry;

[0030] Step (2) Add diatomaceous earth particles with an average pore size of 46 μm and a particle size of 0.8 mm to the Forsythia slurry obtained in step (2), ball mill and stir for 30 min, vacuum stir for 30 min under 0.05 MPa, then add bentonite with a particle size of 2.5 mm to the slurry and stir and mix for 30 min to obtain a cake; the amount of porous medium A added is 8 parts by mass of the dry matter of Forsythia suspensa; the amount of water-absorbing medium B added is 12 parts by mass of the dry matter of Forsythia suspensa.

[0031] Step (3) Mix porous medium C with a particle size of 2 cm and a porosity of ≥30% after wetting into the cake, then put it into a distillation kettle for distillation. Steam at 130℃ is introduced and the gas pressure in the distillation kettle is 0.4 MPa. Maintain for 10 min, then reduce the pressure to 0.15 MPa and distill for 4 h. Finally, reduce the pressure to 0.07 MPa and maintain for 40 min. Collect the distillate and separate to obtain Forsythia suspensa volatile oil. The amount of porous medium C added is 18 parts by mass of the dry matter of Forsythia suspensa.

[0032] Example 2

[0033] A method for distilling Forsythia suspensa volatile oil includes the following steps:

[0034] Step (1) After crushing the dried forsythia fruit into particles with a diameter of 4 mm, mix it with water at a mass ratio of 1:4 and grind it until the particle size D90 is 35 μm to obtain forsythia slurry;

[0035] Step (2) Add diatomaceous earth particles with an average pore size of 43 μm and a particle size of 0.1 mm to the Forsythia slurry obtained in step (2), ball mill and stir for 20 min, vacuum stir for 25 min under 0.06 MPa, then add bentonite with a particle size of 3 mm to the slurry and stir and mix for 40 min to obtain a cake; the amount of porous medium A added is 10 parts by mass of the dry matter of Forsythia suspensa; the amount of water-absorbing medium B added is 10 parts by mass of the dry matter of Forsythia suspensa.

[0036] Step (3) Mix porous medium C with a particle size of 1 cm and a porosity of ≥30% after wetting into the cake, then put it into a distillation kettle for distillation. Steam at 140℃ is introduced and the gas pressure in the distillation kettle is 0.5 MPa. Maintain for 10 min, then reduce the pressure to 0.2 MPa and distill for 3.5 h. Finally, reduce the pressure to 0.06 MPa and maintain for 40 min. Collect the distillate and separate to obtain Forsythia suspensa volatile oil. The amount of porous medium C added is 18 parts by mass of the dry matter of Forsythia suspensa.

[0037] Example 3

[0038] A method for distilling Forsythia suspensa volatile oil includes the following steps:

[0039] Step (1) After crushing the dried forsythia fruit into particles with a diameter of 2 mm, mix it with water at a mass ratio of 1:5 and grind it until the particle size D90 is 42 μm to obtain forsythia slurry;

[0040] Step (2) Add diatomaceous earth particles with an average pore size of 39 μm and a particle size of 0.8 mm to the Forsythia slurry obtained in step (2), ball mill and stir for 20 min, vacuum stir for 30 min under 0.055 MPa, then add bentonite with a particle size of 2.5 mm to the slurry and stir and mix for 30 min to obtain a cake; the amount of porous medium A added is 8 parts by mass of the dry matter of Forsythia suspensa; the amount of water-absorbing medium B added is 13 parts by mass of the dry matter of Forsythia suspensa.

[0041] Step (3) Mix porous medium C with a particle size of 1.5 cm and a porosity of ≥30% after wetting into the cake, then put it into a distillation kettle for distillation. Steam at 120℃ is introduced and the gas pressure in the distillation kettle is 0.3 MPa. Maintain this pressure for 15 min, then reduce the pressure to 0.15 MPa and distill for 5 h. Finally, reduce the pressure to 0.06 MPa and maintain this pressure for 40 min. Collect the distillate and separate to obtain Forsythia suspensa volatile oil. The amount of porous medium C added is 16 parts by mass of the dry matter of Forsythia suspensa.

[0042] Comparative Example 1

[0043] The difference from Example 1 is that a conventional distillation method is used:

[0044] A method for distilling Forsythia suspensa volatile oil includes the following steps:

[0045] The dried forsythia fruit was crushed into particles with a diameter of 1 mm, then soaked in water, and then placed in a distillation kettle for distillation. Steam at a temperature of 130°C was introduced and the distillation was carried out for 15 hours. The distillate was collected and separated to obtain the forsythia volatile oil.

[0046] Comparative Example 2

[0047] The difference from Example 1 is that the Forsythia slurry particle size is too coarse:

[0048] A method for distilling Forsythia suspensa volatile oil includes the following steps:

[0049] Step (1) After crushing the dried forsythia fruit into particles with a diameter of 2 mm, mix it with water at a mass ratio of 1:5 and grind it until the particle size D90 is 102 μm to obtain forsythia slurry;

[0050] Step (2) Add diatomaceous earth particles with an average pore size of 46 μm and a particle size of 0.8 mm to the Forsythia slurry obtained in step (2), ball mill and stir for 30 min, vacuum stir for 30 min under 0.05 MPa, then add bentonite with a particle size of 2.5 mm to the slurry and stir and mix for 30 min to obtain a cake; the amount of porous medium A added is 8 parts by mass of the dry matter of Forsythia suspensa; the amount of water-absorbing medium B added is 12 parts by mass of the dry matter of Forsythia suspensa.

[0051] Step (3) Mix porous medium C with a particle size of 2 cm and a porosity of ≥30% after wetting into the cake, then put it into a distillation kettle for distillation. Steam at 130℃ is introduced and the gas pressure in the distillation kettle is 0.4 MPa. Maintain for 10 min, then reduce the pressure to 0.15 MPa and distill for 4 h. Finally, reduce the pressure to 0.07 MPa and maintain for 40 min. Collect the distillate and separate to obtain Forsythia suspensa volatile oil. The amount of porous medium C added is 18 parts by mass of the dry matter of Forsythia suspensa.

[0052] Comparative Example 3

[0053] The difference from Example 1 is that medium A was not selected:

[0054] A method for distilling Forsythia suspensa volatile oil includes the following steps:

[0055] Step (1) After crushing the dried forsythia fruit into particles with a diameter of 2 mm, mix it with water at a mass ratio of 1:5 and grind it until the particle size D90 is 43 μm to obtain forsythia slurry;

[0056] Step (2) Add bentonite with a particle size of 2.5 mm to the forsythia slurry obtained in step (2), stir and mix for 30 min to obtain a cake; the amount of water-absorbing medium B added is 12 parts by mass of the dry matter of forsythia;

[0057] Step (3) Mix porous medium C with a particle size of 2 cm and a porosity of ≥30% after wetting into the cake, then put it into a distillation kettle for distillation. Steam at 130℃ is introduced and the gas pressure in the distillation kettle is 0.4 MPa. Maintain for 10 min, then reduce the pressure to 0.15 MPa and distill for 4 h. Finally, reduce the pressure to 0.07 MPa and maintain for 40 min. Collect the distillate and separate to obtain Forsythia suspensa volatile oil. The amount of porous medium C added is 18 parts by mass of the dry matter of Forsythia suspensa.

[0058] Comparative Example 4

[0059] The difference from Example 1 is that no absorbent medium B was added:

[0060] A method for distilling Forsythia suspensa volatile oil includes the following steps:

[0061] Step (1) After crushing the dried forsythia fruit into particles with a diameter of 2 mm, mix it with water at a mass ratio of 1:5 and grind it until the particle size D90 is 43 μm to obtain forsythia slurry;

[0062] Step (2) Add diatomaceous earth particles with an average pore size of 46 μm and a particle size of 0.8 mm to the Forsythia slurry obtained in step (2), ball mill and stir for 30 min, and vacuum stir for 30 min under 0.05 MPa to obtain a cake; the amount of porous medium A added is 8 parts by mass of the dry matter of Forsythia slurry.

[0063] Step (3) Mix porous medium C with a particle size of 2 cm and a porosity of ≥30% after wetting into the cake, then put it into a distillation kettle for distillation. Steam at 130℃ is introduced and the gas pressure in the distillation kettle is 0.4 MPa. Maintain for 10 min, then reduce the pressure to 0.15 MPa and distill for 4 h. Finally, reduce the pressure to 0.07 MPa and maintain for 40 min. Collect the distillate and separate to obtain Forsythia suspensa volatile oil. The amount of porous medium C added is 18 parts by mass of the dry matter of Forsythia suspensa.

[0064] Comparative Example 5

[0065] The difference from Example 1 is that porous medium C was not added:

[0066] A method for distilling Forsythia suspensa volatile oil includes the following steps:

[0067] Step (1) After crushing the dried forsythia fruit into particles with a diameter of 2 mm, mix it with water at a mass ratio of 1:5 and grind it until the particle size D90 is 43 μm to obtain forsythia slurry;

[0068] Step (2) Add diatomaceous earth particles with an average pore size of 46 μm and a particle size of 0.8 mm to the Forsythia slurry obtained in step (2), ball mill and stir for 30 min, vacuum stir for 30 min under 0.05 MPa, then add bentonite with a particle size of 2.5 mm to the slurry and stir and mix for 30 min to obtain a cake; the amount of porous medium A added is 8 parts by mass of the dry matter of Forsythia suspensa; the amount of water-absorbing medium B added is 12 parts by mass of the dry matter of Forsythia suspensa.

[0069] Step (3) The cake is loaded into a distillation vessel for distillation. Steam at 130°C is introduced and the pressure inside the distillation vessel is 0.4 MPa. The pressure is maintained for 10 min, then the pressure is reduced to 0.15 MPa and distilled for 4 h. Finally, the pressure is reduced to 0.07 MPa and maintained for 40 min. The distillate is collected and separated to obtain Forsythia suspensa volatile oil. The amount of porous medium C added is 18 parts by mass of the dry matter of Forsythia suspensa.

[0070] Comparative Example 6

[0071] The difference from Example 1 lies in the distillation conditions:

[0072] A method for distilling Forsythia suspensa volatile oil includes the following steps:

[0073] Step (1) After crushing the dried forsythia fruit into particles with a diameter of 2 mm, mix it with water at a mass ratio of 1:5 and grind it until the particle size D90 is 43 μm to obtain forsythia slurry;

[0074] Step (2) Add diatomaceous earth particles with an average pore size of 46 μm and a particle size of 0.8 mm to the Forsythia slurry obtained in step (2), ball mill and stir for 30 min, vacuum stir for 30 min under 0.05 MPa, then add bentonite with a particle size of 2.5 mm to the slurry and stir and mix for 30 min to obtain a cake; the amount of porous medium A added is 8 parts by mass of the dry matter of Forsythia suspensa; the amount of water-absorbing medium B added is 12 parts by mass of the dry matter of Forsythia suspensa.

[0075] Step (3) Mix porous medium C with a particle size of 2 cm and a porosity of ≥30% after wetting into the cake, then put it into a distillation kettle for distillation. Steam at a temperature of 130℃ is introduced and the gas pressure in the distillation kettle is 0.4 MPa. Distill for 5 hours and maintain for 40 minutes. Collect the distillate and separate to obtain Forsythia volatile oil. The amount of porous medium C added is 18 parts by mass of Forsythia dry matter.

[0076] Comparative Example 7

[0077] The difference from Example 1 lies in the distillation conditions:

[0078] A method for distilling Forsythia suspensa volatile oil includes the following steps:

[0079] Step (1) After crushing the dried forsythia fruit into particles with a diameter of 2 mm, mix it with water at a mass ratio of 1:5 and grind it until the particle size D90 is 43 μm to obtain forsythia slurry;

[0080] Step (2) Add diatomaceous earth particles with an average pore size of 46 μm and a particle size of 0.8 mm to the Forsythia slurry obtained in step (2), ball mill and stir for 30 min, vacuum stir for 30 min under 0.05 MPa, then add bentonite with a particle size of 2.5 mm to the slurry and stir and mix for 30 min to obtain a cake; the amount of porous medium A added is 8 parts by mass of the dry matter of Forsythia suspensa; the amount of water-absorbing medium B added is 12 parts by mass of the dry matter of Forsythia suspensa.

[0081] Step (3) Mix porous medium C with a particle size of 2 cm and a porosity of ≥30% after wetting into the cake, then put it into a distillation kettle for distillation. Steam at 100℃ is introduced and the gas pressure in the distillation kettle is 0.1 MPa. Maintain for 10 min, then reduce the pressure to 0.85 MPa and distill for 4 h. Finally, reduce the pressure to 0.03 MPa and maintain for 40 min. Collect the distillate and separate to obtain Forsythia suspensa volatile oil. The amount of porous medium C added is 18 parts by mass of Forsythia suspensa dry matter.

[0082] Process efficiency testing:

[0083] Composition analysis: Agilent 7890B-5977B, DB-WAX capillary column (60m × 0.25mm × 0.25μm)

[0084] Yield calculation: Yield = actual recovered weight / production weight × 100%. The distillate is dehydrated with anhydrous sodium sulfate and then filtered. The theoretical yield of volatile essential oil from Forsythia suspensa is about 2.8%.

[0085] The test results are shown in Table 1:

[0086] Table 1

[0087]

[0088] Examples 1-3 have significant advantages in yield and purity compared to Comparative Examples 1-7, which is due to the design of the process in this scheme.

[0089] Compared to Example 1, conventional techniques, specifically Comparative Example 1, using coarse grinding and atmospheric distillation, only achieved a yield of 1.82% and took 15 hours. This was because the insufficient specific surface area of ​​the raw material resulted in a low cell wall disruption rate, and the extraction rate of high-boiling-point β-caryophyllene (boiling point 256℃) was less than 40% under atmospheric pressure. In contrast, Example 1 used ultrafine grinding of the raw material, resulting in high cell wall disruption, and combined with stepwise pressure distillation (0.4MPa high-pressure cell wall disruption → 0.15MPa steady-state extraction → 0.07MPa finishing), increasing the yield to 2.45% within 4.2 hours.

[0090] Compared to Example 1, when the grinding particle size was relaxed in Comparative Example 2, this was due to the decrease in cell wall breakage rate and the retention of a large amount of oil inside the cells; after omitting the porous medium A in Comparative Example 3, the ultrafine particles easily agglomerated into dense lumps under electrostatic attraction; when the water-absorbing medium B was missing in Comparative Example 4, the material dispersibility deteriorated, and the excess water acted like glue to bind the ultrafine powder particles into dense mud blocks. After heating, the water expanded and further flattened the internal gaps; in Comparative Example 5, no porous medium C was added, and the cake, which lost its skeletal support, cracked open due to heat shrinkage in the distillation kettle, and the steam escaped along the cracks and no longer penetrated the material layer, resulting in a decrease in yield.

[0091] Compared to Example 1, Comparative Example 6, when distilled at a constant pressure of 0.4 MPa, although the cell wall disruption efficiency was high in the initial stage, the continuous high pressure caused the kettle temperature to exceed 140°C, which triggered accelerated dimerization of linalool. At the same time, the light component α-pinene escaped under high turbulence, and the linalyl acetate content eventually dropped to 1.4%. In contrast, when Comparative Example 7 was operated at a low temperature of 100°C and a low pressure of 0.1 MPa, the saturated vapor pressure of β-caryophyllene was much lower than the operating pressure, which could not overcome the mass transfer resistance of the cell wall, resulting in an extraction rate of high-boiling-point components of <20% and a sharp drop in yield to 1.42%.

[0092] Furthermore, in embodiments 1-3 of this scheme, the Forsythia suspensa particles from Moxi are bound by porous media A, water-absorbing media B, and porous media C, making it difficult for them to enter the equipment pipeline with steam and cause blockage.

Claims

1. A method for distilling Forsythia suspensa volatile oil, characterized in that, Includes the following steps: Step (1) After pulverizing the dried forsythia fruit, mix it with water at a mass ratio of 1:3-5 and grind it until the particle size D90≤50μm to obtain forsythia slurry; Step (2) Add porous media A particles with a particle size of 0.5-1mm to the Forsythia slurry obtained in step (1), ball mill and stir for 10-30 minutes, vacuum stir for 20-40 minutes, then add water-absorbing media B to the slurry and stir and mix for 20-40 minutes to obtain a cake; the amount of porous media A added is 5-10 parts by weight of the dry matter of Forsythia suspensa; the amount of water-absorbing media B added is 10-15 parts by weight of the dry matter of Forsythia suspensa. The porous medium A is diatomite or expanded perlite with a pore size of 5-50 μm; The water-absorbing medium B is bentonite or attapulgite with a particle size of 2-3 mm; Step (3) Wetted porous medium C with a particle size of 1-3 cm is mixed into the cake, and then it is loaded into a distillation kettle for distillation. The distillate is collected and separated to obtain Forsythia volatile oil. The amount of porous medium C added is 15-20 parts by weight of the dry matter of Forsythia. The porous medium C is lightweight shale ceramsite or volcanic rock particles with an open porosity of ≥30%. The distillation process in the distillation vessel is as follows: steam at a temperature of 110-140℃ is introduced, the pressure inside the distillation vessel is 0.2-0.5MPa, and it is maintained for 10-15 minutes. Then the pressure is reduced to 0.1-0.2MPa, and distillation is carried out for 3-5 hours. Finally, the pressure is reduced to 0.06-0.08MPa and maintained for 30-60 minutes.

2. The distillation method for Forsythia suspensa volatile oil as described in claim 1, characterized in that, The particle size of the Forsythia fruit granules after crushing in step (1) is 1-5 mm.

3. The distillation method for Forsythia suspensa volatile oil as described in claim 1, characterized in that, During vacuum stirring, the vacuum level is 0.05-0.06 MPa.

4. The distillation method for Forsythia suspensa volatile oil as described in claim 1, characterized in that, Steam at 130℃ was introduced, and the pressure inside the distillation vessel was 0.4MPa. This pressure was maintained for 10 minutes, then reduced to 0.15MPa, and distilled for 4 hours. Finally, the pressure was reduced to 0.07MPa and maintained for 40 minutes. The distillate was collected and separated to obtain Forsythia suspensa volatile oil.

5. The distillation method for Forsythia suspensa volatile oil as described in claim 1, characterized in that, The distillate is separated using extraction or fractionation methods.

6. The distillation method for Forsythia suspensa volatile oil as described in claim 1, characterized in that, The wetting process of the porous medium C after wetting involves immersing it in water and then draining it.

Images