Method for extracting erianin from dendrobium officinale based on supercritical carbon dioxide extraction method

Abstract

The invention relates to the technical field of dendrobium erianin extraction, in particular to a method for extracting dendrobium candidum erianin based on a supercritical carbon dioxide extraction method, which comprises the following steps: crushing dendrobium candidum stems by adopting a crushing tank, a material guide group and a material crushing group; through cooperation of a composite entrainer system ethanol-water-citric acid and a dynamic circulation pressure relief process, the solvent environment is optimized for erianin molecules, and the effects of increasing the extraction rate and reducing solvent residues are achieved by combining the osmotic pressure difference generated by intermittent pressure relief; a fiber bundle structure is opened through coarse slicing, and then secondary crushing is formed through grinding and fine crushing to release cell inclusions, so that the condition of uneven granularity caused by fiber winding a tool bit during rotary cutting of traditional piled raw materials is avoided, erianin oxidation caused by heat generated by friction is avoided, and the effects of increasing the cell wall breaking rate and reducing the erianin heat loss rate are achieved.

Description

Technical Field

[0001] The present invention relates to the technical field of extraction of erianin, and specifically to a method for extracting erianin from Dendrobium officinale based on supercritical carbon dioxide extraction method. Background Art

[0002] As a rare medicinal plant, Dendrobium officinale, its active ingredient erianin has significant anti-tumor and immunomodulatory effects. Traditional extraction processes mainly use organic solvent extraction methods, such as methanol / ethanol reflux, which have problems such as high solvent residues and serious damage to heat-sensitive components. Although supercritical CO2 extraction technology can partially solve the problem of solvent residues, the existing methods still have obvious defects: the extraction rate of erianin by conventional supercritical processes is low because of the insufficient solubility of its phenolic hydroxyl structure in the CO2 phase. In addition, due to fiber entanglement and thermal degradation problems in the existing comminution processes, it is difficult to improve the cell wall breaking rate, which severely restricts the extraction efficiency. Summary of the Invention

[0003] In order to overcome the defects in the prior art, the purpose of the present invention is to provide a method for extracting erianin from Dendrobium officinale based on supercritical carbon dioxide extraction method to solve the problems raised in the above background art.

[0004] To achieve the above purpose, the present invention provides a method for extracting erianin from Dendrobium officinale based on supercritical carbon dioxide extraction method, which uses a comminution tank, a feeding group and a crushing group to carry out comminution treatment on Dendrobium officinale stems, including the following steps:

[0005] I. Raw material pretreatment

[0006] Pour an appropriate amount of Dendrobium officinale stems between the material collecting cylinder and the feeding cylinder in the feeding group, and at the same time turn on the working modes of the vibration group and the crushing group. Under the up-and-down vibration of the feeding cylinder, an appropriate amount of Dendrobium officinale stems are straightly gathered at the lower end of the material collecting cylinder; meanwhile, the crushing plate is driven to rotate to slice the Dendrobium officinale stems exposed at the lower port of the material collecting cylinder, and then they fall onto the screening mesh disk and are dynamically extruded and ground by the accumulated abrasive to break the fiber tissue of the sliced sections;

[0007] Until it is comminuted to 80 - 120 mesh, it is screened and collected from the mesh holes of the screening mesh disk, and then freeze-dried at -25°C to -30°C, and then subjected to pulsed ultrasonic cell wall breaking treatment;

[0008] II. Supercritical CO2 dynamic cycle extraction

[0009] Load the pretreated raw materials into the extraction kettle, set the CO2 flow rate to 25 - 35 L / h, the pressure to 28 - 35 MPa, and the temperature to 45 - 55 °C. Use ethanol - water - citric acid with a volume ratio of 85:13:2 as the composite entrainer. The addition amount of this composite entrainer is 5% - 8% of the raw material mass, and perform 3 - 5 cycles of extraction, with the single - cycle time being 15 - 25 minutes;

[0010] III. Gradient separation

[0011] Pass the liquid after cyclic extraction through the first separation kettle at a pressure of 8 - 10 MPa and a temperature of 30 - 35 °C and the second separation kettle at a pressure of 5 - 6 MPa and a temperature of 25 - 28 °C in sequence for fractionally collecting the crude extract of erianin;

[0012] IV. Refinement

[0013] Purify the crude extract by molecular distillation to obtain erianin with a purity ≥ 95%.

[0014] As a further improvement of this technical solution, a material - gathering cylinder and a material - guiding cylinder are used to gather the raw materials during raw material pretreatment. The material - gathering cylinder is hung inside the upper port of the crushing tank. The upper half of the material - gathering cylinder is funnel - shaped and its lower half is provided with a discharge box. The upper and lower surfaces of the discharge box are open, and a number of partition ribs are equidistantly arranged between its inner walls, thereby dividing the internal space of the discharge box into several discharge channels for guiding the vertical gathering of Dendrobium officinale stems.

[0015] As a further improvement of this technical solution, after gathering the raw materials during raw material pretreatment, the vibration group arranged inside the top of the crushing tank drives the material - guiding cylinder to axially reciprocate and vibrate inside the material - gathering cylinder, so that the vibration - stacked Dendrobium officinale stems turn vertically and enter the discharge channels of the discharge box for gathering; The material - guiding cylinder is coaxially placed inside the material - gathering cylinder. The upper half of the material - guiding cylinder is frustum - shaped and its lower half is funnel - shaped. The outer diameter of the bottom end of the material - guiding cylinder is equal to the inner diameter of the discharge box, and the cone angle of the lower half of the material - guiding cylinder is smaller than the cone angle of the upper half of the material - gathering cylinder, thereby forming a blanking gap.

[0016] As a further improvement of this technical solution, the vibration group drives the material - guiding cylinder to vibrate and shake the materials to adjust the posture. A number of ejector blocks are rotatably and equidistantly embedded on the side wall of the lower half of the material - guiding cylinder. Elastic pieces for elastically pressing it to closely slide along the inner wall of the material - gathering cylinder are arranged inside the ejector blocks. An annular platform is provided at the bottom end of the material - guiding cylinder, and a number of transmission blocks are equidistantly arranged at the inner edge of the bottom surface of the annular platform. The vibration group includes a vibrating disk arranged below the material - guiding cylinder and a servo motor for driving the vibrating disk to horizontally rotate. A number of vibrating blocks for sliding and engaging with a number of transmission blocks are equidistantly arranged at the edge of the top surface of the vibrating disk.

[0017] As a further improvement of this technical solution, a shredding group is adopted to slice and grind the dried stems of Dendrobium officinale exposed from the lower port of the discharge box. The shredding group includes a shredding plate that fits and rotates with the bottom end of the discharge box, a sieve plate net sleeved inside the bottom end of the pulverizing tank, and a main shaft motor. A discharge port penetrating the side wall is formed on the top surface of the shredding plate, and a cutting knife is embedded inside the discharge port. The main shaft motor is installed on the top of the pulverizing tank and is coaxially connected to the shredding plate and the sieve plate net.

[0018] As a further improvement of this technical solution, a servo motor is used to drive the vibrating tray to rotate outside the output shaft of the main shaft motor. A sleeve is sleeved in the central hole of the vibrating tray, and the sleeve is sleeved with the output shaft of the main shaft motor. An end face gear is sleeved at the top end of the sleeve, and a transmission gear meshing with the end face gear is sleeved at the output shaft end of the servo motor. The sleeve passes through the central hole at the top end of the material guiding cylinder.

[0019] As a further improvement of this technical solution, during supercritical CO2 dynamic cycle extraction, the CO2 flow rate is dynamically adjusted in a sine wave pattern, and the fluctuation range is ±3 L / h. After each cycle, the system is depressurized to atmospheric pressure and left to stand for 2 - 3 minutes.

[0020] As a further improvement of this technical solution, during gradient separation, the first separation kettle is set with a pressure gradient of maintaining 10 MPa for the first 10 minutes and then gradually decreasing to 8 MPa.

[0021] As a further improvement of this technical solution, the distillation conditions during molecular distillation purification are an evaporation temperature of 120 °C and a vacuum degree of 0.05 mbar.

[0022] As a further improvement of this technical solution, the final product of erianin obtained by molecular distillation purification is subjected to ultraviolet irradiation sterilization treatment, with a wavelength of 254 nm and a dose of 10 J / cm 2 。

[0023] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0024] 1. For the method of extracting erianin from Dendrobium officinale based on the supercritical carbon dioxide extraction method, through the synergistic effect of the composite entrainer system ethanol - water - citric acid and the dynamic cycle pressure relief process, the solvent environment for erianin molecules is optimized, and the extraction rate is increased and the solvent residue is reduced by combining the osmotic pressure difference generated by intermittent pressure relief.

[0025] 2. For the method of extracting erianin from Dendrobium officinale based on the supercritical carbon dioxide extraction method, by first coarsely slicing to open the fiber bundle structure and then grinding and finely crushing to release the cell inclusions to form secondary crushing, it avoids the situation of fiber entanglement with the cutter head resulting in uneven particle size when the traditional stacked raw materials are rotated and chopped, and avoids the oxidation of erianin caused by frictional heat generation, achieving the effects of improving the cell wall breaking rate and reducing the thermal loss rate of erianin.

[0026] 3. The method for extracting erianin from Dendrobium officinale by supercritical carbon dioxide extraction method integrates the gradient separation pressure gradient and molecular distillation refining to complete the fractional enrichment of the target component and remove macromolecular impurities, achieving the effect of improving the product purity. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] The drawings described herein are for illustrative purposes only and are not intended to limit the scope of the disclosure of the present invention in any way. In addition, the shapes and proportional dimensions of the components in the drawings are only schematic and are used to assist in understanding the present invention, rather than specifically defining the shapes and proportional dimensions of the components of the present invention. Those skilled in the art can select various possible shapes and proportional dimensions according to specific circumstances to implement the present invention under the teaching of the present invention.

[0028] Figure 1 It is a schematic diagram of the overall structure of the present invention;

[0029] Figure 2 It is a schematic diagram of the overall internal assembly structure of the present invention;

[0030] Figure 3 It is a front view of the assembly of the feeding group and the crushing group of the present invention;

[0031] Figure 4 It is a schematic diagram of the structure of the material collecting cylinder in a fully sectioned state of the present invention;

[0032] Figure 5 It is a schematic diagram of the structure of the feeding cylinder in a partially sectioned state of the present invention;

[0033] Figure 6 It is a schematic diagram of the assembly structure of the ejector block of the present invention;

[0034] Figure 7 It is a schematic diagram of the assembly structure of the vibration group of the present invention;

[0035] Figure 8 It is a schematic diagram of the assembly structure of the crushing group of the present invention;

[0036] Figure 9 It is an exploded view of the crushing plate of the present invention;

[0037] The meanings of the various reference numerals in the figure are as follows:

[0038] 100, crushing tank; 110, maintenance door; 120, support cover;

[0039] 200, Feeding Group; 210, Aggregating Cylinder; 211, Discharge Box; 212, Partition Rib; 213, Supporting Ring; 220, Feeding Tube; 221, Through Slot; 2211, Shaft Slot; 222, Pushing Block; 2221, Elastic Sheet; 223, Driving Block; 224, Positioning Post; 225, Ball; 230, Vibration Group; 231, Vibration Tray; 2311, Vibration Block; 232, Servo Motor; 2321, Driving Gear; 233, End Face Gear; 2331, Sleeve

[0040] 300, Crushing Group; 310, Crushing Plate; 3101, Discharge Opening; 3102, Card Slot; 311, Cutting Knife; 320, Screening Mesh Disk; 321, Pushing Rod; 330, Main Shaft Motor; 340, Pushing Part Detailed Embodiment

[0041] Combined with the description of the drawings and the specific embodiments of the present invention, the details of the present invention can be more clearly understood. However, the specific embodiments of the present invention described herein are only for the purpose of explaining the present invention and cannot be understood in any way as a limitation of the present invention. Under the teaching of the present invention, the concepts of those skilled in the art based on any possible deformation of the present invention should be regarded as belonging to the scope of the present invention. The terms "installation" and "connection" should be understood in a broad sense, which can be directly connected or indirectly connected through an intermediate medium

[0042] The orientation or positional relationship indicated by the terms "central axis", "vertical", "horizontal", "front", "rear", "upper", "lower", "left", "right", "top", "bottom", "inner", "outer", etc. used in this article is based on the orientation or positional relationship shown in the drawings, and is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation of the present invention. In addition, in the description of the present invention, the meaning of "several" is two or more, unless otherwise clearly and specifically defined

[0043] Please refer to Figures 1-9 As shown in the figure, the present invention provides a method for extracting erianin from Dendrobium officinale by supercritical carbon dioxide extraction method. The stem of Dendrobium officinale is crushed by using a crushing tank 100, a feeding group 200 and a crushing group 300, including the following steps:

[0044] I. Raw Material Pretreatment

[0045] Pour an appropriate amount of Dendrobium officinale stems into the space between the material collecting cylinder 210 and the material guiding cylinder 220 in the material guiding group 200. At the same time, turn on the working modes of the vibration group 230 and the material crushing group 300. Under the up-and-down vibration of the material guiding cylinder 220, the appropriate amount of Dendrobium officinale stems gather straight at the lower end of the material collecting cylinder 210. Meanwhile, the crushing plate 310 is driven to rotate to slice the Dendrobium officinale stems exposed at the lower port of the material collecting cylinder 210, and then they fall onto the screening mesh plate 320 and are dynamically ground by the piled abrasive to cut off the fiber tissue of the slices.

[0046] Add dry ice to the abrasive, accounting for 10% of the raw material amount, to achieve a material temperature ≤ 15°C and solve the problem of the thermal degradation of erianin caused by traditional crushing. Among them, the abrasive is selected as zirconia ceramic beads with a diameter of 3 - 5 mm.

[0047] Until it is crushed to 80 - 120 mesh, it is screened and dropped from the mesh holes of the screening mesh plate 320 and collected. After freeze-drying at -25°C to -30°C, pulsed ultrasonic cell wall breaking treatment is carried out. The parameters of the pulsed ultrasonic wave are: frequency 28 kHz, power 600 W, pulse period 5 s on / 3 s off, and the total treatment time is 15 minutes. Discontinuous treatment avoids local overheating and improves the cell wall breaking rate. First, rough slicing is carried out to open the fiber bundle structure, and then grinding and fine crushing are carried out to release the cell inclusions to form secondary crushing, avoiding the uneven particle size caused by the fiber winding around the cutter head when the traditional piled raw materials are rotated and chopped; avoiding the oxidation of erianin caused by frictional heat generation.

[0048] II. Supercritical CO2 dynamic circulation extraction

[0049] Load the pretreated raw materials into the extraction kettle, and add 0.1% β-cyclodextrin as an embedding agent to the raw materials. Set the CO2 flow rate to 25 - 35 L / h, the pressure to 28 - 35 MPa, and the temperature to 45 - 55°C. Use ethanol-water-citric acid with a volume ratio of 85:13:2 as a composite entrainer, and the citric acid concentration in the composite entrainer is 0.5 mol / L. The addition amount of this composite entrainer is 5% - 8% of the raw material mass, and 3 - 5 times of cyclic extraction are carried out, with the single-cycle time being 15 - 25 minutes.

[0050] III. Gradient separation

[0051] Pass the liquid after cyclic extraction through the first separation kettle with a pressure of 8 - 10 MPa and a temperature of 30 - 35°C and the second separation kettle with a pressure of 5 - 6 MPa and a temperature of 25 - 28°C in sequence to fractionally collect the crude extract of erianin; realize the integrated process from crude extraction to high purity and reduce the loss in intermediate steps.

[0052] IV. Refinement

[0053] Purify the crude extract by molecular distillation to obtain erianin with a purity ≥ 95%.

[0054] Effect of Different Extraction Conditions on the Extraction Rate of Erianin:

[0055]

[0056] The ternary system of ethanol - water - citric acid produces a synergistic solubilization effect, which improves the solubility in view of the phenolic hydroxyl structure of erianin; by changing the osmotic pressure difference inside and outside the cells through intermittent pressure relief, the traditional continuous extraction mode is broken through, and the extraction rate is improved.

[0057] General Process Table for Extracting Erianin from Dendrobium officinale by Supercritical CO2:

[0058]

[0059]

[0060] Vertically, the table is divided into blocks according to the process stages: pretreatment - extraction - separation - purification - recycling, and horizontally lists the operation steps - parameters - technical points.

[0061] Furthermore, as Figures 3-6 shown, when pre - treating the raw materials, the material - gathering cylinder 210 and the material - guiding cylinder 220 are used to gather the raw materials. The material - gathering cylinder 210 is hung inside the upper port of the crushing tank 100. The upper half of the material - gathering cylinder 210 is funnel - shaped and its lower half is provided with a discharge box 211. The upper and lower surfaces of the discharge box 211 are open and a number of partition ribs 212 are equidistantly arranged between its inner walls, thereby dividing the internal space of the discharge box 211 into several discharge channels for guiding the vertical aggregation of Dendrobium officinale stems, so that the Dendrobium officinale stems are transversely sliced when discharging, destroying the integrity of the fibers.

[0062] Furthermore, when pre - treating the raw materials, after gathering the raw materials, the vibration group 230 arranged inside the top of the crushing tank 100 drives the material - guiding cylinder 220 to axially reciprocate inside the material - gathering cylinder 210, so that the stacked Dendrobium officinale stems turn vertically and enter the discharge channels of the discharge box 211 to gather; the material - guiding cylinder 220 is coaxially placed inside the material - gathering cylinder 210. The upper half of the material - guiding cylinder 220 is frustum - shaped and its lower half is funnel - shaped. The outer diameter of the bottom end of the material - guiding cylinder 220 is equal to the inner diameter of the discharge box 211, and the taper angle of the lower half of the material - guiding cylinder 220 is smaller than the taper angle of the upper half of the material - gathering cylinder 210, thereby forming a blanking gap, so that the Dendrobium officinale stems accurately enter the discharge channels of the discharge box 211.

[0063] Specifically, the vibration group 230 drives the material guiding cylinder 220 to vibrate and adjust its posture for discharging materials. A plurality of ejector blocks 222 are rotatably embedded at equal intervals on the side wall of the lower half of the material guiding cylinder 220. An elastic sheet 2221 for elastically pressing and sliding closely against the inner wall of the material collecting cylinder 210 is arranged inside the ejector block 222. As the material guiding cylinder 220 vibrates axially, the ejector block 222 always slides in contact with the inner wall of the material collecting cylinder 210, and the stacked Dendrobium officinale stems are pushed open to prevent them from crossing and blocking the falling; an annular platform is arranged at the bottom end of the material guiding cylinder 220, and a plurality of transmission blocks 223 are arranged at equal intervals at the inner edge of the bottom surface of the annular platform. The lower end of the elastic sheet 2221 is fixed on the top surface of the annular platform, and the upper end of the elastic sheet 2221 fits against the inner side surface of the ejector block 222, forming a state of elastically ejecting the ejector block 222 outwards.

[0064] Specifically, the vibration group 230 includes a vibrating disk 231 arranged below the material guiding cylinder 220 and a servo motor 232 for driving the vibrating disk 231 to rotate horizontally. A plurality of vibrating blocks 2311 for slidingly engaging with a plurality of transmission blocks 223 are arranged at equal intervals at the edge of the top surface of the vibrating disk 231; both the transmission block 223 and the vibrating block 2311 are in an arc block structure. When the upper end of the vibrating block 2311 contacts the lower end of the transmission block 223, the rotating vibrating disk 231 uses the vibrating block 2311 to slide upwards against the transmission block 223 to jack up the material guiding cylinder 220; when the vibrating block 2311 slides between two adjacent transmission blocks 223, the material guiding cylinder 220 drops, thus forming a vibrating state.

[0065] Further, a plurality of through grooves 221 are arranged at equal intervals on the side wall of the lower half of the material guiding cylinder 220. The ejector block 222 is slidably engaged with the through groove 221. Axial grooves 2211 are symmetrically arranged at the inner bottom of the through groove 221. The ejector block 222 is fan-shaped and a pin is inserted at its central angle end. The pin is rotatably engaged with the axial groove 2211; a supporting ring 213 is arranged at the top of the inner wall of the discharge box 211. A plurality of limit columns 224 are rotatably embedded at equal intervals at the outer edge of the bottom surface of the annular platform at the bottom end of the material guiding cylinder 220. The limit columns 224 are inserted and slidably engaged with the supporting ring 213. A nut is threadedly connected to the bottom end of the limit column 224, and a spring is sleeved outside the limit column 224 above the nut. The elastic force of the spring assists the material guiding cylinder 220 to vibrate and reset.

[0066] Specifically, as Figures 7-9As shown, a crushing group 300 is used to slice and grind the stems of Dendrobium officinale exposed from the lower end of the discharge box 211. The crushing group 300 includes a crushing plate 310 that rotates in contact with the bottom end of the discharge box 211, a sieving mesh disk 320 sleeved in the bottom end of the crushing tank 100, and a spindle motor 330. The top surface of the crushing plate 310 is provided with a discharge port 3101 that passes through the side wall, and the inner side of the discharge port 3101 is provided with a slot 3102. The cutter 311 is clamped in the slot 3102 and is fixed by bolts. The spindle motor 330 is fixedly connected; the spindle motor 330 is installed on the top of the crushing tank 100 and is coaxially connected to the particle board 310 and the screen mesh disk 320. The top surface of the screen mesh disk 320 is provided with a plurality of material shifting rods 321 radiating in an annular shape, which are used to block the bottom layer of abrasive material so that the crushed material in the grinding mesh can fall down; a shifting member 340 fixedly connected to the output shaft of the spindle motor 330 is provided above the screen mesh disk 320, which is used to disturb the abrasive material accumulated on the screen mesh disk 320, and then mix and grind it with the slices.

[0067] Furthermore, a servo motor 232 is used to drive the vibrating disc 231 to rotate outside the output shaft of the spindle motor 330. The top cover of the crushing tank 100 is provided with a support cover 120, and the spindle motor 330 and the servo motor 232 are both installed on the support cover 120; a maintenance door 110 is hinged on the side wall of the crushing tank 100 for maintaining the internal structure of the crushing tank 100 and cleaning the tank body; a sleeve 2331 is provided in the center hole of the vibrating disc 231, and the sleeve 2331 is sleeved with the output shaft of the spindle motor 330, and the top end of the sleeve 2331 is sleeved with an end gear 233, and the output shaft end of the servo motor 232 is sleeved with a transmission gear 2321 meshing with the end gear 233, and the sleeve 2331 passes through the top center hole of the guide barrel 220, so that the driving force of the spindle motor 330 does not affect the rotation speed of the vibrating disc 231, thereby controlling the vibration amplitude of the guide barrel 220.

[0068] Furthermore, a plurality of balls 225 are embedded in the inner wall of the top end of the guide tube 220 in an annular shape at equal intervals. The plurality of balls 225 are in rolling contact with the outer wall of the sleeve 2331 to prevent the guide tube 220 from rotating synchronously with the sleeve 2331 and can move freely up and down on the outer wall of the sleeve 2331.

[0069] It should be noted that the above embodiments are only for illustrating the technical concept and features of the present invention, and their purpose is to enable people familiar with the technology to understand the content of the present invention and implement it accordingly, and they cannot be used to limit the protection scope of the present invention. Any equivalent changes or modifications made according to the spirit of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for extracting erianin from Dendrobium officinale by supercritical carbon dioxide extraction method, which uses a pulverizing tank (100), a feeding group (200) and a crushing group (300) to pulverize the stems of Dendrobium officinale, and is characterized in that, It includes the following steps: I. Raw material pretreatment Pour an appropriate amount of Dendrobium officinale stems between the material collecting cylinder (210) and the material guiding cylinder (220) in the material guiding group (200). At the same time, turn on the working modes of the vibration group (230) and the material crushing group (300). Under the up-and-down vibration of the material guiding cylinder (220), the appropriate amount of Dendrobium officinale stems are gathered straight at the lower end of the material collecting cylinder (210). Meanwhile, the crushing plate (310) is driven to rotate to slice the Dendrobium officinale stems exposed at the lower port of the material collecting cylinder (210). Then, they fall onto the screening mesh disk (320) and the fibrous tissues of the sliced segments are dynamically ground and broken by the piled abrasive materials; Until it is crushed to 80 - 120 meshes, it is screened and dropped from the mesh holes of the screening mesh disk (320) and collected. After freeze-drying at -25°C to -30°C, pulsed ultrasonic cell wall breaking treatment is carried out; II. Supercritical CO2 dynamic cycle extraction Load the pretreated raw materials into the extraction kettle. Set the CO2 flow rate to 25 - 35 L / h, the pressure to 28 - 35 MPa, and the temperature to 45 - 55°C. Use ethanol - water - citric acid with a volume ratio of 85:13:2 as the composite entrainer. The addition amount of this composite entrainer is 5% - 8% of the raw material mass, and carry out 3 - 5 cycles of extraction, with the single cycle time being 15 - 25 minutes; III. Gradient separation The liquid after cycle extraction is passed through the first separation kettle with a pressure of 8 - 10 MPa and a temperature of 30 - 35°C and the second separation kettle with a pressure of 5 - 6 MPa and a temperature of 25 - 28°C in sequence for fractionally collecting the crude extract of erianin; IV. Refinement Purify the crude extract by molecular distillation to obtain erianin with a purity ≥ 95%.

2. The method for extracting erianin from Dendrobium officinale by supercritical carbon dioxide extraction method according to claim 1, wherein: During raw material pretreatment, the material collecting cylinder (210) and the material guiding cylinder (220) are used to gather the raw materials. The material collecting cylinder (210) is hung inside the upper port of the crushing tank (100). The upper half of the material collecting cylinder (210) is funnel-shaped and its lower half is provided with a discharge box (211). The upper and lower surfaces of the discharge box (211) are open and a number of partition ribs (212) are equidistantly arranged between its inner walls, thereby dividing the internal space of the discharge box (211) into a number of discharge channels for guiding the vertical gathering of Dendrobium officinale stems.

3. The method for extracting erianin from Dendrobium officinale by supercritical carbon dioxide extraction method according to claim 2, wherein: During raw material pretreatment, after gathering the raw materials, the vibration group (230) arranged inside the top of the crushing tank (100) drives the material guiding cylinder (220) to axially reciprocate inside the material collecting cylinder (210), so that the piled and vibrating Dendrobium officinale stems turn vertically and enter the discharge channels of the discharge box (211) to gather. The material guiding cylinder (220) is coaxially placed inside the material collecting cylinder (210). The upper half of the material guiding cylinder (220) is frustum-shaped and its lower half is funnel-shaped. The outer diameter of the bottom end of the material guiding cylinder (220) is equal to the inner diameter of the discharge box (211), and the cone angle of the lower half of the material guiding cylinder (220) is smaller than the cone angle of the upper half of the material collecting cylinder (210), thereby forming a blanking gap.

4. The method for extracting erianin from Dendrobium officinale by supercritical carbon dioxide extraction method according to claim 3, wherein: The vibrating group (230) is used to drive the material guiding cylinder (220) to vibrate and shake the material to adjust the attitude. A number of ejector blocks (222) are rotatably embedded in the side wall of the lower half of the material guiding cylinder (220) at equal intervals. An elastic sheet (2221) for elastically pressing it against the inner wall of the material collecting cylinder (210) and sliding is arranged inside the ejector block (222). An annular platform is arranged at the bottom end of the material guiding cylinder (220), and a number of transmission blocks (223) are arranged at equal intervals at the inner edge of the bottom surface of the annular platform. The vibrating group (230) includes a vibrating disk (231) arranged below the material guiding cylinder (220) and a servo motor (232) for driving the vibrating disk (231) to rotate horizontally. A number of vibrating blocks (2311) that are slidably clamped with a number of transmission blocks (223) are arranged at equal intervals at the top edge of the top surface of the vibrating disk (231).

5. The method for extracting erianin from dendrobium officinale by supercritical carbon dioxide extraction method according to claim 4, characterized in that: The crushing group (300) is used to slice and grind the dendrobium officinale stems exposed from the lower port of the discharge box (211). The crushing group (300) includes a crushing plate (310) that fits and rotates with the bottom end of the discharge box (211), a sieve mesh disk (320) sleeved inside the bottom end of the crushing tank (100), and a main shaft motor (330). A discharge port (3101) penetrating the side wall is opened on the top surface of the crushing plate (310). A cutting knife (311) is embedded inside the discharge port (3101). The main shaft motor (330) is installed on the top of the crushing tank (100) and is coaxially connected to the crushing plate (310) and the sieve mesh disk (320).

6. The method for extracting erianin from Dendrobium officinale based on the supercritical carbon dioxide extraction method according to claim 5, wherein: The servo motor (232) is used to drive the vibrating disk (231) to rotate outside the output shaft of the main shaft motor (330). A sleeve (2331) is sleeved in the central hole of the vibrating disk (231), and the sleeve (2331) is sleeved with the output shaft of the main shaft motor (330). An end face gear (233) is sleeved at the top end of the sleeve (2331). A transmission gear (2321) meshing with the end face gear (233) is sleeved at the output shaft end of the servo motor (232). The sleeve (2331) passes through the central hole at the top end of the material guiding cylinder (220).

7. The method for extracting erianin from Dendrobium officinale by supercritical carbon dioxide extraction method according to claim 6, wherein: During supercritical CO2 dynamic cycle extraction, the CO2 flow rate is dynamically adjusted in a sine wave manner, and the fluctuation range is ±3 L / h. After each cycle, the system is depressurized to atmospheric pressure and left to stand for 2 - 3 minutes.

8. The method for extracting erianin from Dendrobium officinale by supercritical carbon dioxide extraction method according to claim 7, characterized in that: During gradient separation, the first separation kettle is set with a pressure gradient of maintaining 10 MPa for the first 10 minutes and gradually decreasing to 8 MPa subsequently.

9. The method for extracting erianin from Dendrobium officinale by supercritical carbon dioxide extraction method according to claim 8, wherein: The distillation conditions during molecular distillation purification are an evaporation temperature of 120 °C and a vacuum degree of 0.05 mbar.

10. The method for extracting erianin from Dendrobium officinale by supercritical carbon dioxide extraction method according to claim 9, wherein: The final product of erianin obtained by molecular distillation purification is sterilized by ultraviolet irradiation, with a wavelength of 254 nm and a dose of 10 J / cm 2 .

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