Vacuum freeze-drying process for dendrobium officinale

Abstract

The application discloses a vacuum freeze-drying process of Dendrobium officinale, which comprises the following steps: S1, pretreatment, picking, washing, filtering and drying water stains of collected Dendrobium officinale, and cutting the Dendrobium officinale into small pieces; S2, freezing, placing the pretreated material in a material tray, and placing the material tray in a freeze dryer, and starting the freeze dryer; S3, then, the temperature of a cold trap in the freeze dryer is lowered to-30 to-40 DEG C at a speed of 0.25 to 0.35 DEG C per minute, the temperature of the material is lowered to-15 to-16 DEG C, the temperature of an oil tank is lowered to-15 to-16 DEG C, and the continuous operation lasts for 2 to 2.5 hours; S4, then, delaying for 20 minutes, starting a vacuum pump, and extracting vacuum until the freeze drying is completed; and S5. The vacuum freeze-drying process of Dendrobium officinale has outstanding advantages compared with traditional sun drying, boiling drying, spray drying and vacuum drying of Dendrobium officinale, guarantees the thermal stability of the Dendrobium officinale, can best maintain the original shape of the Dendrobium officinale, and has a long preservation period of the Dendrobium officinale.

Description

TECHNICAL FIELD

[0001] The present application relates to the processing technology field of Dendrobium candidum, in particular to a vacuum freeze-drying process of Dendrobium candidum. BACKGROUND

[0002] At present, after Dendrobium candidum is harvested, the redundant root hairs, leaf tips and inflorescence residues on the stem are removed by pruning, and the remaining fresh Dendrobium is washed and laid in a ventilated and cool place. In order to make the fresh Dendrobium with high water content and straight strip easy to curl, a lot of effort is still needed. First, the fresh Dendrobium is fried or baked at low temperature, and then it is rubbed with uniform force to remove part of the water in the fresh strip and make it slowly become soft. The Dendrobium strip after rubbing is dried for three days or is baked at low temperature to make it continue to soften, and then it is manually curled and buckled. The Dendrobium being shaped is placed on the material frame, the Dendrobium drying machine is started, the temperature range is set to medium-high temperature, the temperature is set to 70-75 degrees, and the Dendrobium drying process is generally completed in 4-5 days according to the size. After baking for 1 day, the machine needs to be stopped for 3 to 5 hours, and then it continues to be baked. This repeated process actually saves power consumption, and the internal moisture of the Dendrobium is transferred to the outer layer for re-drying. The existing Dendrobium drying mostly adopts the above-mentioned method.

[0003] Vacuum freeze-drying is a method of freezing the water-containing material into solid state first, and then sublimating the water in the solid state into gas state, so as to remove the water and preserve the material.

[0004] Compared with the usual drying, boiling, spray drying and vacuum drying, freeze-drying has the following outstanding advantages:

[0005] (1) Freeze-drying is dried at low temperature, which will not cause protein denaturation, but can make microorganisms lose biological activity. This is particularly suitable for the drying and preservation of biological active products, biochemical products, genetic engineering products and blood products, etc. which have poor thermal stability.(2) In the process of low-temperature drying, the growth of microorganisms and the action of enzymes are almost impossible, so that the original properties of the material can be best maintained.(3) After drying, the volume and shape are basically unchanged, the material is in a sponge-like state, there is no shrinkage, and when rehydrated, the contact area with water is large, so that the original shape can be quickly restored.(4) Because it is usually dried in vacuum, there is little oxygen, so the easily oxidized substances are protected.(5) It can remove 95% to 99.5% of the water in the material, and the preservation period of the product is long.

[0006] Freeze-drying technology has incomparable advantages over other drying methods, and is more and more favored by people. At present, it has been widely used in medicine, biological products, food, active substances and other fields, and its application scale is still rapidly expanding. Vacuum freeze-drying will become an important application technology in the 21st century. Therefore, it is urgent to design a vacuum freeze-drying process of Dendrobium candidum to solve the above problems. SUMMARY

[0007] The purpose of the present application is to provide a Dendrobium officinale vacuum freeze-drying process to solve the above-mentioned deficiencies in the prior art.

[0008] In order to achieve the above-mentioned purpose, the present application provides the following technical solutions:

[0009] A Dendrobium officinale vacuum freeze-drying process, comprising the following steps:

[0010] S1: pretreatment, picking, washing, filtering water stains, and cutting the collected Dendrobium officinale into small pieces;

[0011] S2: freeze, pour the pretreated material into the material tray, and place it in the freeze dryer, and start the freeze dryer equipment;

[0012] S3: then the cold trap temperature in the freeze dryer is reduced at a speed of 0.25-0.35℃ per minute to -30- -40℃, the material temperature is reduced to -15- -16℃, the oil tank temperature is reduced to -15- -16℃, and the continuous running time is 2-2.5 hours;

[0013] S4: then delay for 20 minutes, start the vacuum pump, and extract the vacuum until the freeze-drying is completed;

[0014] S5: then the cold trap temperature in the freeze dryer is reduced at a speed of 0.25-0.35℃ per minute to -40- -49℃, the material temperature is reduced to -16- -30℃, the oil tank temperature is raised to 0℃, and the continuous running time is 0.5-1 hour;

[0015] S6: then the heating conductive oil tank temperature is raised at a speed of 0.25-0.35℃ per minute to 80-85℃ until the freeze-drying is completed;

[0016] S7: then the material temperature is raised at a speed of 0.25-0.35℃ per minute from -16- -30℃ to 60-65℃, the cold trap temperature is kept at about -40℃, and the continuous running time is 7-8 hours;

[0017] S8: then after the material temperature is raised to 60-65℃, keep for 1-2 hours, and end the freeze dryer equipment.

[0018] Further, in S1, when the Dendrobium officinale is cut into pieces, the cutting specification of the Dendrobium officinale is controlled to be 1-3 cm long.

[0019] Further, steps S3 to S8 are the automatic running state after the freeze dryer equipment is started.

[0020] Further, in S2, the operation steps for starting the freeze dryer equipment are,

[0021] S21, open the water inlet valve, close the water outlet valve, fill the water tank with tap water until the water outlet overflows, then close the water inlet valve;

[0022] S22, turn on the power of the freeze-drying machine equipment, enter the touch screen interface of the freeze-drying machine equipment, and click arbitrarily to enter the main menu interface;

[0023] S23, click "flowchart" to enter the flowchart interface;

[0024] S24, set parameters, click "parameters" to enter the parameter setting interface, and select temperature mode 1 to set corresponding parameters;

[0025] S25, evenly pour the dendrobium candidum into the material tray, and then close the tank door;

[0026] S26, check whether the backwater valve, exhaust valve, and defrosting valve switches are in the closed state, and whether the icons on the touch screen interface and the physical valve state are consistent;

[0027] S27, after closing the valves, click "mode switch" in the flowchart interface, switch to "mode switch automatic", and then click "start". The freeze-drying machine equipment will automatically start running after a delay;

[0028] S28, freeze-drying process: freezing: observe the temperature of the material, the temperature of the cold trap, the temperature of the oil tank, and the temperature of the plate heat exchanger in the flowchart interface. More intuitive changes can be clicked "back" in the flowchart interface, enter the main menu interface, and then click "temperature curve" to enter the temperature curve interface;

[0029] S29, freeze-drying end: observe the temperature values of the material in the flowchart interface, which reach the set temperature of the material. Enter the temperature curve interface to observe the temperature curve of the material temperature 1, material temperature 2, and material temperature 3, which all reach the set temperature of the material. After the three lines coincide, delay for more than 60 minutes, and the drying is complete. Return to the "flowchart" interface, click "stop", and the equipment stops running. Then open the freeze-drying chamber buckle. Click the "exhaust valve" icon to open the exhaust valve for air supply, and open the freeze-drying chamber door to discharge the material.

[0030] Further, in the parameter setting of S24,

[0031] Set temperature 1: 80-85℃, heating oil tank temperature, upper limit temperature of heated conductive oil;

[0032] Set temperature 2: 70-75℃, upper limit temperature of the material; material limit temperature: 60-65℃,

[0033] Current control value: display the current temperature of the oil tank;

[0034] Fan rotation time: 300 seconds;

[0035] Material temperature: -20 to -15℃;

[0036] Cold trap temperature: -30 to -25℃;

[0037] The open-rotor disc pump is delayed for 20 to 30 minutes, and the purpose of the delay is to make the material more solid when frozen. When the material temperature and the cold trap temperature reach the set temperature, the vacuum pump is started. After the parameters are set, click "Return" to enter the flowchart interface again.

[0038] Further, in the S25 step, the number of material trays is set according to the freeze-drying equipment, and each tray of material is 2.8-3 kg. Then, the material temperature probes K1, K2 and K3 are placed in the middle of the material on the material tray in order, which can correctly represent the center temperature of the largest and thickest material.

[0039] Further, in the S28, vacuum drying: when the material temperature and the cold trap temperature reach the set parameters, the vacuum pump is started. At the same time, the oil tank circulates the heat transfer oil to the plate exchanger, and the temperature of the plate exchanger rises. The moisture in the plate exchanger sublimates from a solid state to a gaseous state. The equipment automatically extracts vacuum to discharge the gaseous moisture, and the drying process is in progress.

[0040] Further, after the freeze-drying is completed in the S29, defrosting: after the material is discharged, click the "water return valve open" and "defrosting valve" icons, and then click the "defrosting pump" icon. The defrosting pump is started. After defrosting for 1-2 hours, click the "defrosting pump" icon again to stop defrosting. After 30 minutes of defrosting, the next freeze-drying can be performed.

[0041] Further, after the defrosting is completed, turn off the power and open the water tank outlet valve to empty the circulating water in the water tank. The vacuum freeze-drying is completed.

[0042] In the above technical solution, the present application provides a kind of Dendrobium officinale Kimura et Migo vacuum freeze-drying process, the present application adopts to Dendrobium officinale Kimura et Migo vacuum freeze-drying process, compared with the traditional sun-drying, boiling dry, spray drying and vacuum drying of Dendrobium officinale Kimura et Migo has outstanding advantages, guarantees the thermal stability of Dendrobium officinale Kimura et Migo, can best keep the original shape of Dendrobium officinale Kimura et Migo, the preservation period of Dendrobium officinale Kimura et Migo is long. BRIEF DESCRIPTION OF DRAWINGS

[0043] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings needed in the embodiments. Obviously, the drawings described below are only some embodiments described in the present application, and other drawings can also be obtained by those skilled in the art based on these drawings.

[0044] Figure 1 The process flowchart is provided for the Dendrobium officinale Kimura et Migo vacuum freeze-drying process embodiment of the present application.

[0045] Figure 2 The main menu interface diagram provided by the embodiment of the Dendrobium officinale vacuum freeze-drying process.

[0046] Figure 3 The flowchart interface diagram provided by the embodiment of the Dendrobium officinale vacuum freeze-drying process.

[0047] Figure 4 The input parameter setting interface diagram provided by the embodiment of the Dendrobium officinale vacuum freeze-drying process.

[0048] Figure 5 The temperature curve interface diagram provided by the embodiment of the Dendrobium officinale vacuum freeze-drying process.

[0049] Figure 6 The abnormal shutdown reason and solution method diagram provided by the embodiment of the Dendrobium officinale vacuum freeze-drying process. DETAILED DESCRIPTION

[0050] In order to make the skilled in the art better understand the technical solutions of the present application, the present application will be further described in detail below with reference to the drawings.

[0051] As shown in Figures 1-5 The embodiment of the present application provides a Dendrobium officinale vacuum freeze-drying process, which comprises the following steps:

[0052] S1: pretreatment, picking, washing, filtering water stains, and cutting the collected Dendrobium officinale into small sections;

[0053] S2: freezing, pouring the pretreated material into a material tray, and placing it in a freeze dryer, and starting the freeze dryer equipment;

[0054] S3: then the cold trap temperature in the freeze dryer is cooled at a speed of 0.25-0.35℃ per minute to-30 to-40℃, the material temperature is cooled to-15 to-16℃, the oil tank temperature is cooled to-15 to-16℃, and the continuous running time is 2-2.5 hours;

[0055] S4: then delay for 20 minutes, start the vacuum pump, and extract the vacuum until the freeze-drying is completed;

[0056] S5: then the cold trap temperature in the freeze dryer is cooled at a speed of 0.25-0.35℃ per minute to-40 to-49℃, the material temperature is cooled to-16 to-30℃, the oil tank temperature is raised to 0℃, and the continuous running time is 0.5-1 hour;

[0057] S6: then the heating conductive oil tank temperature is raised at a speed of 0.25-0.35℃ per minute to 80-85℃ until the freeze-drying is completed;

[0058] S7: Then the material temperature is raised from -16 to -30℃ to 60-65℃ at a rate of 0.25-0.35℃ per minute, the cold trap temperature is kept at about -40℃, and the continuous operation lasts for 7-8 hours;

[0059] S8: After the material temperature is raised to 60-65℃, it is kept for 1-2 hours, and the freeze dryer device is ended.

[0060] As an embodiment provided by the present application, in S1, when the dendrobium officinale is cut into segments, the cutting specification of the dendrobium officinale is controlled to be 1-3 cm long.

[0061] As another embodiment provided by the present application, steps S3 to S8 are the automatic running state after the freeze dryer device is started.

[0062] In S2, the operation steps for starting the freeze dryer device are,

[0063] S21, open the water inlet valve, close the water outlet valve, fill the water tank with tap water until the water outlet overflows, and then close the water inlet valve;

[0064] S22, turn on the power of the freeze dryer device, enter the touch screen interface of the freeze dryer device, and click arbitrarily to enter the main menu interface, as shown in Figure 2 ;

[0065] S23, click "flowchart" to enter the flowchart interface, as shown in Figure 3 ;

[0066] S24, set the parameters, click "parameters" to enter the parameter setting interface, and select the temperature mode to set the corresponding parameters, as shown in Figure 4 ;

[0067] S25, evenly pour the dendrobium officinale into the material tray, and then close the tank door;

[0068] S26, check whether the backwater valve, exhaust valve, and defrosting valve are in the closed state, and check whether the icons on the touch screen interface and the physical valve state are consistent;

[0069] S27, after the valves are closed, click "mode switch" in the flowchart interface to switch to "mode switch automatic", and then click "start", and the freeze dryer device automatically starts running after a delay;

[0070] S28, freeze drying process: freezing: observe the temperature of the material (K1, K2, K3), the cold trap temperature (-30℃), the oil tank temperature, and the plate exchange temperature change in the flowchart interface, and more intuitive changes can be clicked in the flowchart interface "back", enter the main menu interface, and then click "temperature curve" to enter the temperature curve interface, as shown inFigure 5 As shown;

[0071] S29, freeze-drying is completed: observe the temperature values ​​(60°C) of the materials (K1, K2, K3) in the flow chart interface, and all reach the material set temperature (60°C); enter the temperature curve interface, observe the temperature curves of material temperature 1, material temperature 2, and material temperature 3 in the temperature curve, and the values ​​all reach the material set temperature. After the three lines coincide and are delayed for more than 60 minutes, the drying is completed; return to the "flow chart" interface, click "Stop", the equipment stops running, and then open the freeze-drying chamber buckle; click the "Exhaust Valve" icon, the exhaust valve opens to replenish air, and the freeze-drying chamber door opens to discharge the material.

[0072] As an embodiment provided by the present invention, in the setting parameters of S24,

[0073] Set temperature 1: 80~85℃, actual setting: 85℃, heating oil tank temperature, upper limit temperature after thermal oil heating;

[0074] Set temperature 2: 70-75℃ material upper limit temperature, actual setting: 75℃; material limit temperature: 60-65℃, actual setting: 65℃,

[0075] Current control value: displays the current temperature of the fuel tank;

[0076] Fan rotation time: 300 seconds;

[0077] Material temperature: -20~-15℃, actual setting: -15℃;

[0078] Cold trap temperature: -30~-25℃, actual setting: -30℃;

[0079] Delay for starting the rotary vane pump: 20 to 30 minutes, actual setting: 20 minutes. The purpose of the delay is to make the material frozen more solid. When the material temperature and the cold trap temperature reach the set temperature, the vacuum pump will start. After the parameter setting is completed, click "Return" to enter the flow chart interface again. Figure 3 shown.

[0080] As an embodiment provided by the present invention, in step S25, the number of material trays is set accordingly according to the freeze dryer equipment, and each tray of material is 2.8-3 kg. Then, the material temperature probes K1, K2, and K3 are placed in the middle of the material on the material tray in sequence, which can correctly indicate the center temperature of the largest and thickest material.

[0081] As another embodiment provided by the present application, in S28, vacuum drying: when the material temperature and the cold trap temperature reach the set parameters, the vacuum pump is started, and the oil tank heat transfer oil is circulated to the plate heat exchanger, the temperature of the plate heat exchanger rises, and the moisture therein sublimates from a solid state to a gaseous state. The device automatically extracts vacuum to discharge the gaseous moisture, and drying is in progress.

[0082] As another embodiment provided by the present application, after S29, freeze drying is completed, and defrosting is performed: after the discharging is completed, the "water return valve open" and "defrosting valve" icons are clicked, and then the "defrosting pump" icon is clicked. The defrosting pump is started, and the defrosting is performed for 1-2 hours. Then, the "defrosting pump" is clicked again to stop the defrosting. After the defrosting is stopped for 30 minutes, the next freeze drying can be performed.

[0083] As another embodiment provided by the present application, after the defrosting is completed, the power supply is turned off, the water tank water outlet valve is opened, and the water tank circulating water is emptied. The vacuum freeze drying is completed.

[0084] Abnormal stop processing:

[0085] The freeze dryer is not allowed to be powered off or manually stopped during the freeze drying stage. Otherwise, the freeze drying of the material will fail partially or completely. If an unexpected stop occurs, the following processing is performed:

[0086] 1. Open the "exhaust valve", and wait for the freeze drying chamber door to open for discharging. Then, the discharge is placed in a cold storage. After the fault is eliminated, the defrosting is performed as needed, and the operation is restarted according to the operation steps.

[0087] 2. If the stop fault can be quickly eliminated, no action is taken. After the fault is eliminated, the following steps are performed:

[0088] 1) If the vacuum state has not been entered, do not empty after the stop. The vacuum degree of the tank body is maintained. After the fault is eliminated, the power supply is turned on again, the controller is reset, and the machine is started again.

[0089] 2) If the vacuum state has been entered, but the heating state has not been entered, do not empty after the stop. The vacuum degree of the tank body is maintained. After the fault is eliminated, the power supply is turned on again, the controller is reset, the fan power switch is turned off, the parameter setting interface is changed, the "cold well temperature" setting value is changed (to be changed to the original value next time), the setting value is higher than the K1, K2 and K3 values, and then the machine is started again.

[0090] 3) If the heating state has been entered, do not empty after the stop. The vacuum degree of the tank body is maintained. After the fault is eliminated, the power supply is turned on again, the controller is reset, the fan positive and negative rotation intermediate power supply is removed, the "cold well temperature" setting value is changed (to be changed to the original value next time), the setting value is higher than the K1, K2 and K3 values, and then the machine is started again.

[0091] Abnormal stop reasons and solutions, such asFigure 6 are shown.

[0092] The foregoing description of certain exemplary embodiments of the application has been presented for the purposes of illustration and description. It is not intended to be exhaustive or to limit the application to the precise form disclosed. Many modifications and variations are possible in light of the above teaching. It is intended that the scope of the application be limited not with this detailed description, but rather by the claims appended hereto.

Claims

1. A vacuum freeze-drying process for Dendrobium officinale, characterized in that: The following steps are involved: S1: Pretreatment: picking and washing the collected Dendrobium officinale, draining the water stains, and cutting into small pieces; S2: Freeze, pour the pre-treated material into the material tray, place it in the freeze dryer, and start the freeze dryer equipment; S3: Then the temperature of the cold trap in the freeze dryer is cooled to -30--40°C at a rate of 0.25-0.35°C per minute, the material temperature is cooled to -15--16°C, and the oil tank temperature is cooled to -15--16°C. The continuous operation time is 2-2.5 hours; S4: Then, the vacuum pump is started for 20 minutes to draw the vacuum until the freeze-drying is completed; S5: Then the temperature of the cold trap in the freeze dryer is cooled to -40 to -49°C at a rate of 0.25 to 0.35°C per minute, the material temperature is cooled to -16 to -30°C, and the oil tank temperature is raised to 0°C. The continuous operation time is 0.5 to 1 hour; S6: Then, the temperature of the thermal oil tank is heated to 80-85°C at a rate of 0.25-0.35°C per minute until the freeze-drying is completed; S7: The material temperature is then raised from -16 to -30°C to 60 to 65°C at a rate of 0.25 to 0.35°C per minute, and the cold trap temperature is maintained at around -40°C. The continuous operation lasts for 7 to 8 hours. S8: Then the material temperature is raised to 60-65°C and maintained for 1-2 hours, and the freeze dryer equipment is terminated.

2. The vacuum freeze-drying process for Dendrobium officinale according to claim 1, wherein: In S1, when cutting the Dendrobium officinale into segments, the length of the segments is controlled to be 1-3 cm.

3. The vacuum freeze-drying process for Dendrobium officinale according to claim 1, wherein: Steps S3 to S8 are the automatic operation state after the freeze dryer equipment is started.

4. The vacuum freeze-drying process for Dendrobium officinale according to claim 1, wherein: In S2, the operation steps of starting the freeze dryer equipment are: S21, open the water inlet valve, close the water outlet valve, fill the water tank with tap water until the water outlet overflows, and then close the water inlet valve; S22, turn on the power of the freeze dryer device, enter the touch screen interface of the freeze dryer device, and click anywhere to enter the main menu interface; S23. Click "Flowchart" to enter the flowchart interface; S24. Set parameters. Click "Parameters" to enter the parameter setting interface. Select temperature mode 1 and set the corresponding parameters. S25. Pour the Dendrobium officinale evenly into the material tray, and then close the box door; S26. Check whether the return valve, exhaust valve, and defrost valve are closed, and verify whether the icons on the touch screen interface match the actual valve status; S27. After the valve is closed, click "Mode Switch" in the flow chart interface to switch to "Mode Switch Automatic", then click "Start", and the freeze dryer will automatically start running after a delay; S28. Freeze-drying process: Freezing: Observe the changes in material temperature, cold trap temperature, oil tank temperature, and plate changer temperature on the flow chart interface. For more intuitive changes, click "Return" on the flow chart interface to enter the main menu interface, and then click "Temperature Curve" to enter the temperature curve interface; S29, freeze-drying is completed: observe the temperature values ​​of the materials in the flow chart interface and all reach the material set temperature; enter the temperature curve interface and observe the temperature curves of material temperature 1, material temperature 2, and material temperature 3. The values ​​all reach the material set temperature. After the three lines coincide and the delay is more than 60 minutes, the drying is completed; return to the "flow chart" interface, click "Stop" to stop the equipment, and then open the freeze-drying chamber buckle; click the "Exhaust Valve" icon, the exhaust valve opens to replenish air, and the freeze-drying chamber door opens to discharge the material.

5. The vacuum freeze-drying process for Dendrobium officinale according to claim 4, wherein: In the setting parameters of S24, Set temperature 1: 80-85℃, heating oil tank temperature, upper limit temperature of thermal oil after heating; Set temperature 2: 70-75℃ material upper limit temperature; material limit temperature: 60-65℃, Current control value: displays the current temperature of the fuel tank; Fan rotation time: 300 seconds; Material temperature: -20~-15℃; Cold trap temperature: -30~-25℃; Delay for starting the rotary vane pump: 20 to 30 minutes. The purpose of the delay is to make the material frozen more solid. When the material temperature and the cold trap temperature reach the set temperature, the vacuum pump will start. After the parameter setting is completed, click "Return" to enter the flow chart interface again.

6. The vacuum freeze-drying process for Dendrobium officinale according to claim 4, characterized in that: In step S25, the number of material trays is set according to the freeze dryer equipment, with each tray weighing 2.8-3 kg. Material temperature probes K1, K2, and K3 are placed in the middle of the material on the material tray in sequence, which can correctly indicate the center temperature of the largest and thickest material.

7. The vacuum freeze-drying process for Dendrobium officinale according to claim 4, characterized in that: In S28, vacuum drying: when the material temperature and cold trap temperature reach the set parameters, the vacuum pump will start. At the same time, the heat transfer oil in the oil tank circulates to the plate exchanger. The plate exchanger temperature rises, and the moisture in it sublimates from solid to gas. The equipment automatically extracts vacuum to discharge the gaseous moisture, and drying is in progress.

8. The vacuum freeze-drying process for Dendrobium officinale according to claim 4, characterized in that: After S29, freeze-drying is completed, defrost: After the discharge is completed, click the "return valve open" and "defrost valve" icons, and then click the "defrost pump" icon to start the defrost pump. After defrosting for 1-2 hours, click "defrost pump" again to stop defrosting. The next freeze-drying can be carried out 30 minutes after defrosting stops.

9. The vacuum freeze-drying process for Dendrobium officinale according to claim 8, characterized in that: After defrosting is completed, turn off the power, open the water outlet valve of the water tank, empty the circulating water in the water tank, and the vacuum freeze drying is completed.

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