Distillation method of fructus forsythiae volatile oil

Abstract

The invention relates to the field of separation and purification, in particular to a distillation method of fructus forsythiae volatile oil, which comprises the following steps: (1) crushing dried fructus forsythiae fruits, mixing the crushed fructus forsythiae fruits with water according to a mass ratio of 1: (3-5), and grinding until the particle size D90 is less than or equal to 50 microns to obtain fructus forsythiae slurry; 2, porous medium A particles with the particle size being 0.5-1 mm and a water absorption medium B are added into the fructus forsythiae slurry obtained in the step 2, stirring and mixing are conducted for 20-40 min, and a material cake is obtained; and (3) mixing a wetted porous medium C with the particle size of 1-3cm into the material cake, then loading into a distillation kettle for distillation, collecting distillate, and separating to obtain the fructus forsythiae volatile oil. According to the scheme, the distillation process flow is optimized, the distillation efficiency is improved, and the problem of blockage caused by too fine grinding of raw materials is solved, so that the requirements of industrial production on efficient and stable extraction of fructus forsythiae volatile oil are met.

Description

Technical Field

[0001] The invention relates to the field of separation and purification, and in particular to a distillation method for Forsythia suspensa volatile oil. Background Art

[0002] With the continuous development of traditional Chinese medicine volatile oil extraction technology, Forsythia suspensa volatile oil has become a research hotspot due to its significant pharmacological activity. However, distillation is the most efficient, commonly used, and mature method for extracting Forsythia suspensa volatile oil. However, 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 enough, the distillation efficiency is low, while if it is ground too finely, it easily clogs the equipment.

[0003] After searching, a method for processing Forsythia suspensa and the processed Forsythia suspensa was disclosed with the publication number CN108379352B, which was published on November 10, 2020. This patent provides a method for extracting Forsythia suspensa volatile oil through the steps of cold storage, steam sterilization, initial drying and re-drying, which can effectively control the content of volatile oil and other active ingredients in Forsythia suspensa. However, this technical solution has high requirements for the pretreatment of raw materials, especially the need for multi-step temperature control operations, which makes the process complicated and time-consuming.

[0004] After searching, a method for preparing a Mongolian medicine, Sulongga-4, was disclosed with publication number CN108114149B on November 17, 2020. This patent uses steam distillation to extract volatile oil from Forsythia suspensa and combines it with other medicinal extracts to make granules. Although this method can better retain the active ingredients of volatile oils, its distillation process is relatively traditional and lacks clear guidance on the control of raw material particle size. It is easy for the distillation equipment to be blocked due to over-fine grinding of the raw materials, thus affecting production continuity and efficiency. Summary of the Invention

[0005] In order to make up for the above shortcomings, the present invention provides a distillation method for Forsythia suspensa volatile oil, which aims to optimize the distillation process, improve the distillation efficiency, and solve the blockage problem caused by over-fine grinding of raw materials, thereby meeting the demand for efficient and stable extraction of Forsythia suspensa volatile oil in industrial production.

[0006] In order to achieve the above object, the present invention adopts the following technical solutions:

[0007] A distillation method for Forsythia suspensa volatile oil comprises the following steps:

[0008] Step (1) crushing the dried Forsythia suspensa fruit and mixing it with water in a mass ratio of 1:3-5, and grinding the mixture to a particle size D90≤50 μm to obtain a Forsythia suspensa slurry;

[0009] Step (2) adding porous medium A particles with a particle size of 0.5-1 mm to the Forsythia suspensa slurry obtained in step (2), ball milling and stirring for 10-30 minutes, vacuum stirring treatment for 20-40 minutes, and then adding water-absorbing medium B to the slurry, stirring and mixing for 20-40 minutes to obtain a cake; the amount of porous medium A added is 5-10 parts by mass of the dry matter mass of Forsythia suspensa; the amount of water-absorbing medium B added is 10-15 parts by mass of the dry matter mass of Forsythia suspensa;

[0010] In step (3), the wetted porous medium C having a particle size of 1-3 cm is mixed into the cake, which is then placed in 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 weight based on the dry matter mass of Forsythia suspensa. The distillate is preferably subjected to conventional extraction or fractionation.

[0011] The overall design concept of this solution is to minimize the particle size of the Forsythia fruit particles as much as possible to improve the distillation effect. However, in conventional technology, the reduced particle size of the Forsythia fruit particles can easily clog the equipment during the distillation process, causing problems such as production stagnation. During the distillation process, this solution uses porous medium A to absorb tiny Forsythia fruit particles. Through vacuum stirring, some of the Forsythia fruit particles enter the pores of porous medium A. Because porous medium A is a hydrophilic medium, the deep pores will be filled with water, that is, most of the Forsythia fruit particles that enter the pores are on the outside of the pores. During the heating and distillation process, the water in the pores evaporates due to the heat, carrying out the volatile substances of the Forsythia fruit particles in the pores. Secondly, the water-absorbing medium B is mainly used to absorb the moisture in the remaining slurry and disperse the slurry that has absorbed the Forsythia fruit particles as much as possible, thereby increasing the steam contact area. Porous medium C acts as a skeleton. At the same time, porous medium C is a wetted particle, which can provide more contact surface during the distillation process and serves as a secondary source of steam.

[0012] Secondly, the present scheme controls the temperature, pressure and water vapor conditions of the distillation process, optimizes and adjusts the distillation efficiency, and enables the stable and high-quality distillation of the volatile oil of Forsythia suspensa.

[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 enables the Forsythia suspensa particles to be well adsorbed and even embedded in the 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 light shale ceramsite or volcanic rock particles with an open porosity of ≥30%.

[0017] Preferably, the particle size of the Forsythia suspensa fruit particles after crushing in step (1) is 1-5 mm.

[0018] In order to save costs, the porous medium A, water-absorbing medium B and porous medium C selected in this scheme are all recyclable materials. The recycling method is to calcine at 150-250℃ for 1-2 hours to regenerate, and then reuse after screening.

[0019] Preferably, during the vacuum stirring treatment, the vacuum degree is 0.05-0.06 MPa.

[0020] Preferably, the distillation process of the still is as follows: introducing water vapor with a temperature of 110-140°C, the air pressure in the still is 0.2-0.5MPa, maintaining for 10-15min, then reducing the pressure to 0.1-0.2MPa, distilling for 3-5h, and finally reducing the pressure to 0.06-0.08MPa, maintaining for 30-60min.

[0021] Preferably, the wetting process of the porous medium C after being wetted is soaking in water and then draining.

[0022] This scheme is divided into three pressure swing distillations: 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 oil; a medium-pressure stage of 0.1-0.2 MPa for 3-5 hours to maintain steady-state distillation; and a low-pressure final stage of 0.06-0.08 MPa to extract high-boiling point sesquiterpenes (such as β-caryophyllene) to increase 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 medium B, an adsorption-dispersion-skeleton structure is established, which overcomes the problem of distillation equipment clogging caused by over-fine grinding of raw materials, thereby affecting production continuity and efficiency.

[0025] 2. Based on the adsorption-dispersion-skeleton structure, the distillation process is optimized and the distillation efficiency and recovery rate are improved. DETAILED DESCRIPTION

[0026] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0027] Example 1

[0028] A distillation method for Forsythia suspensa volatile oil comprises the following steps:

[0029] Step (1) grinding the dried Forsythia suspensa fruit into a particle size of 2 mm, mixing the mixture with water at a mass ratio of 1:5, and grinding the mixture to a particle size D90 of 43 μm to obtain a Forsythia suspensa slurry;

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

[0031] In step (3), a porous medium C with a particle size of 2 cm and a porosity of ≥30% after wetting is mixed into the cake, and then the cake is placed in a distillation kettle for distillation, and water vapor at a temperature of 130° C. is introduced. The air pressure in the distillation kettle is 0.4 MPa and maintained for 10 minutes. The pressure is then reduced to 0.15 MPa and distilled for 4 hours. Finally, the pressure is reduced to 0.07 MPa and maintained for 40 minutes. 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 mass of Forsythia suspensa.

[0032] Example 2

[0033] A distillation method for Forsythia suspensa volatile oil comprises the following steps:

[0034] Step (1) grinding the dried Forsythia suspensa fruit into particles of 4 mm in size, mixing the particles with water in a mass ratio of 1:4, and grinding the particles to a particle size D90 of 35 μm to obtain a Forsythia suspensa slurry;

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

[0036] In step (3), a porous medium C with a particle size of 1 cm and a porosity of ≥30% after wetting is mixed into the material cake, and then the material cake is placed in a distillation kettle for distillation, and water vapor at a temperature of 140° C. is introduced. The air pressure in the distillation kettle is 0.5 MPa and maintained for 10 minutes. The pressure is then reduced to 0.2 MPa and distilled for 3.5 hours. Finally, the pressure is reduced to 0.06 MPa and maintained for 40 minutes. 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 mass of Forsythia suspensa.

[0037] Example 3

[0038] A distillation method for Forsythia suspensa volatile oil comprises the following steps:

[0039] Step (1) grinding the dried Forsythia suspensa fruit into particles of 2 mm in size, mixing the particles with water in a mass ratio of 1:5, and grinding the particles to a particle size D90 of 42 μm to obtain a Forsythia suspensa slurry;

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

[0041] In step (3), a porous medium C with a particle size of 1.5 cm and a porosity of ≥30% after wetting is mixed into the cake, and then the cake is placed in a distillation kettle for distillation, and water vapor at a temperature of 120° C. is introduced. The air pressure in the distillation kettle is 0.3 MPa and maintained for 15 minutes. The pressure is then reduced to 0.15 MPa and distilled for 5 hours. Finally, the pressure is reduced to 0.06 MPa and maintained for 40 minutes. The distillate is collected and separated to obtain Forsythia suspensa volatile oil; the amount of porous medium C added is 16 parts by mass of the dry matter mass of Forsythia suspensa.

[0042] Comparative Example 1

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

[0044] A distillation method for Forsythia suspensa volatile oil comprises the following steps:

[0045] The dried Forsythia suspensa fruits were crushed into particles of 1 mm in size, immersed in water, and then placed in a distillation kettle for distillation. Water vapor at a temperature of 130° C. was introduced and distilled for 15 hours. The distillate was collected and separated to obtain Forsythia suspensa volatile oil.

[0046] Comparative Example 2

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

[0048] A distillation method for Forsythia suspensa volatile oil comprises the following steps:

[0049] Step (1) grinding the dried Forsythia suspensa fruit into a particle size of 2 mm, mixing the mixture with water at a mass ratio of 1:5, and grinding the mixture to a particle size D90 of 102 μm to obtain a Forsythia suspensa slurry;

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

[0051] In step (3), a porous medium C with a particle size of 2 cm and a porosity of ≥30% after wetting is mixed into the cake, and then the cake is placed in a distillation kettle for distillation, and water vapor at a temperature of 130° C. is introduced. The air pressure in the distillation kettle is 0.4 MPa and maintained for 10 minutes. The pressure is then reduced to 0.15 MPa and distilled for 4 hours. Finally, the pressure is reduced to 0.07 MPa and maintained for 40 minutes. 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 mass of Forsythia suspensa.

[0052] Comparative Example 3

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

[0054] A distillation method for Forsythia suspensa volatile oil comprises the following steps:

[0055] Step (1) grinding the dried Forsythia suspensa fruit into a particle size of 2 mm, mixing the mixture with water at a mass ratio of 1:5, and grinding the mixture to a particle size D90 of 43 μm to obtain a Forsythia suspensa slurry;

[0056] Step (2) adding bentonite with a particle size of 2.5 mm to the Forsythia suspensa slurry obtained in step (2), stirring and mixing for 30 minutes to obtain a cake; the amount of water-absorbing medium B added is 12 parts by mass of the dry matter mass of Forsythia suspensa;

[0057] In step (3), a porous medium C with a particle size of 2 cm and a porosity of ≥30% after wetting is mixed into the cake, and then the cake is placed in a distillation kettle for distillation, and water vapor at a temperature of 130° C. is introduced. The air pressure in the distillation kettle is 0.4 MPa and maintained for 10 minutes. The pressure is then reduced to 0.15 MPa and distilled for 4 hours. Finally, the pressure is reduced to 0.07 MPa and maintained for 40 minutes. 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 mass of Forsythia suspensa.

[0058] Comparative Example 4

[0059] The difference from Example 1 is that no water absorbing medium B is added:

[0060] A distillation method for Forsythia suspensa volatile oil comprises the following steps:

[0061] Step (1) grinding the dried Forsythia suspensa fruit into a particle size of 2 mm, mixing the mixture with water at a mass ratio of 1:5, and grinding the mixture to a particle size D90 of 43 μm to obtain a Forsythia suspensa slurry;

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

[0063] In step (3), a porous medium C with a particle size of 2 cm and a porosity of ≥30% after wetting is mixed into the cake, and then the cake is placed in a distillation kettle for distillation, and water vapor at a temperature of 130° C. is introduced. The air pressure in the distillation kettle is 0.4 MPa and maintained for 10 minutes. The pressure is then reduced to 0.15 MPa and distilled for 4 hours. Finally, the pressure is reduced to 0.07 MPa and maintained for 40 minutes. 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 mass of Forsythia suspensa.

[0064] Comparative Example 5

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

[0066] A distillation method for Forsythia suspensa volatile oil comprises the following steps:

[0067] Step (1) grinding the dried Forsythia suspensa fruit into a particle size of 2 mm, mixing the mixture with water at a mass ratio of 1:5, and grinding the mixture to a particle size D90 of 43 μm to obtain a Forsythia suspensa slurry;

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

[0069] Step (3) The cake is charged into a distillation kettle for distillation, and water vapor at a temperature of 130° C. is introduced. The air pressure in the distillation kettle is 0.4 MPa and maintained for 10 minutes. The pressure is then reduced to 0.15 MPa and distilled for 4 hours. Finally, the pressure is reduced to 0.07 MPa and maintained for 40 minutes. 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 mass of Forsythia suspensa.

[0070] Comparative Example 6

[0071] The difference from Example 1 is that the distillation conditions are different:

[0072] A distillation method for Forsythia suspensa volatile oil comprises the following steps:

[0073] Step (1) grinding the dried Forsythia suspensa fruit into a particle size of 2 mm, mixing the mixture with water at a mass ratio of 1:5, and grinding the mixture to a particle size D90 of 43 μm to obtain a Forsythia suspensa slurry;

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

[0075] In step (3), a porous medium C with a particle size of 2 cm and a porosity of ≥30% after wetting is mixed into the cake, and then the cake is placed in a distillation kettle for distillation. Water vapor at a temperature of 130° C. is introduced, the air pressure in the distillation kettle is 0.4 MPa, and distillation is maintained for 5 hours and 40 minutes. 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 mass of Forsythia suspensa.

[0076] Comparative Example 7

[0077] The difference from Example 1 is that the distillation conditions are different:

[0078] A distillation method for Forsythia suspensa volatile oil comprises the following steps:

[0079] Step (1) grinding the dried Forsythia suspensa fruit into a particle size of 2 mm, mixing the mixture with water at a mass ratio of 1:5, and grinding the mixture to a particle size D90 of 43 μm to obtain a Forsythia suspensa slurry;

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

[0081] In step (3), a porous medium C with a particle size of 2 cm and a porosity of ≥30% after wetting is mixed into the material cake, and then the material cake is placed in a distillation kettle for distillation, and water vapor at a temperature of 100° C. is introduced. The air pressure in the distillation kettle is 0.1 MPa and maintained for 10 minutes. The pressure is then reduced to 0.85 MPa and distilled for 4 hours. Finally, the pressure is reduced to 0.03 MPa and maintained for 40 minutes. 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 mass of Forsythia suspensa.

[0082] Process efficiency testing:

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

[0084] Recovery rate calculation: Referring to GB / T 17529-2021 General test method for plant essential oils, the distillate was dehydrated with anhydrous sodium sulfate and then filtered. The theoretical recovery rate of volatile essential oil of Forsythia suspensa was about 2.8%.

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

[0086] Table 1

[0087]

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

[0089] The conventional technique, Comparative Example 1, achieved only a 1.82% yield and took 15 hours to produce the product, compared to Example 1, using coarse grinding and atmospheric distillation. This was due to the insufficient specific surface area of the raw material, resulting in a low cell wall disruption rate, and the extraction rate of the high-boiling-point β-caryophyllene (boiling point 256°C) was less than 40% under atmospheric pressure. In contrast, Example 1 utilized ultrafine grinding of the raw material to achieve high cell wall disruption, combined with step-pressure distillation (0.4 MPa high-pressure cell wall blasting → 0.15 MPa steady-state extraction → 0.07 MPa final extraction), increasing the yield to 2.45% within 4.2 hours.

[0090] Compared with Example 1, when the grinding particle size is relaxed in Comparative Example 2, this is due to the decrease in cell wall breaking rate and the retention of a large amount of oil in the cells; after the porous medium A is omitted in Comparative Example 3, the ultrafine particles are easily agglomerated into dense blocks under electrostatic attraction; when the water-absorbing medium B is missing in Comparative Example 4, the dispersion of the material becomes worse, and the excess water acts like glue to bond the ultrafine powder particles into dense mud blocks. After heating, the water expands and further squeezes the internal gaps; in Comparative Example 5, the porous medium C is not added, and the material cake without skeleton support shrinks and cracks in the distillation kettle due to heat, and the steam escapes along the cracks and no longer penetrates the material layer, resulting in a decrease in yield.

[0091] Compared with Example 1, when Comparative Example 6 adopted a constant pressure of 0.4 MPa distillation, although the cell wall breaking efficiency was high in the initial stage, the continuous high pressure caused the kettle temperature to exceed 140°C, which triggered the accelerated dimerization of linalool. At the same time, the light component α-pinene escaped under high turbulence, and the final linalyl acetate content dropped to 1.4%; while 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, and it was unable to overcome the cell wall mass transfer resistance, resulting in the extraction rate of high-boiling point components less than 20%, and the yield dropped sharply to 1.42%.

[0092] In addition, in Examples 1-3 of this solution, the Forsythia suspensa particles from Moxi are constrained by the porous medium A, the water-absorbing medium B, and the porous medium C, making it difficult for them to enter the equipment pipeline along with the steam and cause blockage.

Claims

1. A distillation method for Forsythia suspensa volatile oil, characterized in that: The following steps are involved: Step (1) crushing the dried Forsythia suspensa fruit and mixing it with water in a mass ratio of 1:3-5, and grinding the mixture to a particle size D90≤50 μm to obtain a Forsythia suspensa slurry; Step (2) adding porous medium A particles with a particle size of 0.5-1 mm to the Forsythia suspensa slurry obtained in step (2), ball milling and stirring for 10-30 minutes, vacuum stirring treatment for 20-40 minutes, and then adding water-absorbing medium B to the slurry, stirring and mixing for 20-40 minutes to obtain a cake; the amount of porous medium A added is 5-10 parts by mass of the dry matter mass of Forsythia suspensa; the amount of water-absorbing medium B added is 10-15 parts by mass of the dry matter mass of Forsythia suspensa; Step (3) The wetted porous medium C with a particle size of 1-3 cm is mixed into the material cake, which is then placed in a distillation kettle for distillation, and the distillate is collected and separated to obtain the Forsythia suspensa volatile oil; the amount of the porous medium C added is 15-20 parts by weight of the dry matter mass of the Forsythia suspensa.

2. The distillation method of the volatile oil of Forsythia suspensa according to claim 1, wherein The porous medium A is diatomaceous earth or expanded perlite, with a pore size of 5-50 μm.

3. The distillation method of the volatile oil of Forsythia suspensa according to claim 1, wherein The water absorbing medium B is bentonite or attapulgite with a particle size of 2-3 mm.

4. The distillation method of the volatile oil of Forsythia suspensa according to claim 1, wherein The porous medium C is light shale ceramsite or volcanic rock particles with an open porosity of ≥30%.

5. The distillation method of Forsythia suspensa volatile oil according to claim 1, wherein The particle size of the Forsythia suspensa fruit particles after crushing in step (1) is 1-5 mm.

6. The distillation method of Forsythia suspensa volatile oil according to claim 1, wherein: During the vacuum stirring treatment, the vacuum degree is 0.05-0.06MPa.

7. The distillation method of Forsythia suspensa volatile oil according to claim 1, wherein: The distillation process of the still is as follows: introducing water vapor with a temperature of 110-140° C., the air pressure in the still is 0.2-0.5 MPa, maintaining for 10-15 minutes, then reducing the pressure to 0.1-0.2 MPa, distilling for 3-5 hours, and finally reducing the pressure to 0.06-0.08 MPa, maintaining for 30-60 minutes.

8. The distillation method of Forsythia suspensa volatile oil according to claim 7, wherein: Water vapor at a temperature of 130°C was introduced, and the air pressure in the distillation kettle was 0.4MPa, maintained for 10 minutes, then the pressure was reduced to 0.15MPa, distilled for 4 hours, and 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.

9. The distillation method of Forsythia suspensa volatile oil according to claim 1, wherein: The distillate is separated by extraction or fractionation.

10. The distillation method of Forsythia suspensa volatile oil according to claim 1, characterized in that: The wetting process of the porous medium C after wetting is to soak it in water and then drain it.

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