A preparation method of cordyceps sinensis

Abstract

The application discloses a preparation method of cordyceps sinensis, and relates to the technical field of medicine preparation. A specific implementation mode of the method comprises the following steps: cooling the cleaned cordyceps sinensis to a first temperature which is lower than a eutectic point, so that the water in the cordyceps sinensis is completely frozen to form ice crystals; performing at least one freeze-thaw cycle, wherein the freeze-thaw cycle comprises the following steps: increasing the temperature to a second temperature which is higher than 0 DEG C, so that the frozen cordyceps sinensis is thawed, and then the temperature is decreased to the first temperature at a second decreasing rate, so that the cordyceps sinensis is re-frozen; placing the cordyceps sinensis in a vacuum environment, and performing at least one pressure change treatment; and performing temperature increasing drying under the vacuum condition, until a predetermined water content is reached. The implementation mode significantly improves the dissolution rate of effective substances when the user takes the cordyceps sinensis, and improves the bioavailability of the cordyceps sinensis; uniform, loose and crisp textures are formed, so that a unique taste of melting in the mouth is brought, and the problem of hard taste and poor palatability of traditional freeze-dried cordyceps sinensis is solved.

Description

Technical Field

[0001] This invention relates to the field of pharmaceutical preparation technology, and in particular to a method for preparing Cordyceps sinensis. Background Technology

[0002] Cordyceps sinensis (referred to as Cordyceps) is a precious Chinese medicinal herb. Its traditional preparation methods mainly include natural sun drying, hot air drying, and the more advanced vacuum freeze drying (freeze drying).

[0003] While traditional sun-drying or baking methods are less expensive, the high processing temperatures can easily cause the decomposition or oxidation of heat-sensitive active ingredients in cordyceps (such as cordycepin and adenosine), resulting in the loss of medicinal components. At the same time, high-temperature dehydration causes the cell walls to shrink rapidly and tightly encapsulate the contents, forming a dense structure. This makes it difficult for the active substances to be released from the cells when brewing or decocting, resulting in low bioavailability.

[0004] Vacuum freeze-drying technology, by directly sublimating frozen water in a vacuum environment, effectively preserves the initial form and heat-sensitive components of cordyceps. However, the ice crystals formed during conventional freeze-drying are relatively small, limiting their physical damage to cell walls. The microstructure of dried cordyceps products remains relatively dense, resulting in a hard and brittle texture, a "gritty" or chewy feel, and a lack of the crisp, melt-in-your-mouth experience. More importantly, this dense structure still hinders the efficient dissolution of active ingredients. Summary of the Invention

[0005] In view of this, the present invention provides a method for preparing Cordyceps sinensis. By subjecting Cordyceps sinensis to ultra-low temperature pre-freezing and repeated freeze-thaw treatment, large ice crystals can be formed inside the Cordyceps sinensis, which can effectively pierce or tear cell walls and vacuolar membranes. This physically opens up channels for the release of active substances (polysaccharides, cordycepin, etc.) from inside the cells, significantly improving the dissolution rate of active substances when consumed by the user and increasing the bioavailability of Cordyceps sinensis. By subjecting Cordyceps sinensis to vacuum pressure treatment, the residual gas or vapor inside the Cordyceps sinensis expands due to the pressure reduction, which can cause the porous network structure already formed inside the Cordyceps sinensis to expand in volume. This not only accelerates the drying rate, but more importantly, forms a uniform, loose, and crisp texture, resulting in a unique melt-in-your-mouth taste. This solves the problem of the hard texture and poor palatability of traditional freeze-dried Cordyceps sinensis.

[0006] To achieve the above objectives, according to one aspect of the present invention, a method for preparing Cordyceps sinensis is provided, comprising: cooling the washed Cordyceps sinensis to a first temperature below the eutectic point at a first cooling rate, so that the water inside the Cordyceps sinensis is completely frozen to form ice crystals; subjecting the frozen Cordyceps sinensis to at least one freeze-thaw cycle, the freeze-thaw cycle comprising thawing the frozen Cordyceps sinensis by raising the temperature to a second temperature above 0°C, and then refreezing it by cooling it to the first temperature at a second cooling rate; placing the Cordyceps sinensis subjected to the freeze-thaw cycle in a vacuum environment and performing at least one pressure-switching treatment by changing the chamber pressure of a freeze dryer; and heating and drying the pressure-switched Cordyceps sinensis under vacuum conditions until a predetermined moisture content is reached.

[0007] Optionally, the number of freeze-thaw cycles and the number of pressure-changing treatments are both 1 to 5 times.

[0008] Optionally, the first temperature is -70°C to -50°C, and both the first cooling rate and the second cooling rate are 1°C / min to 5°C / min.

[0009] Optionally, the step of raising the temperature to a second temperature above 0°C to thaw the frozen Cordyceps sinensis includes: raising the temperature to a second temperature above 0°C at a set heating rate and maintaining it for a period of time to thaw the frozen Cordyceps sinensis.

[0010] Optionally, the second temperature is 20°C to 30°C, the heating rate is 1°C / min to 5°C / min, and the time period is not less than 30 minutes.

[0011] Optionally, the pressure transformation process includes: reducing the chamber pressure to a negative pressure state below atmospheric pressure and maintaining it for a certain period of time, and then restoring it to an atmospheric pressure state.

[0012] Optionally, the pressure transformation process includes: reducing the chamber pressure to a negative pressure state below atmospheric pressure and maintaining it for a certain period of time, and then filling it with dry inert gas to a positive pressure state.

[0013] Optionally, the pressure of the negative pressure state is 0.05 MPa, and the certain time is 10 to 30 minutes.

[0014] Optionally, the pressure in the positive pressure state is 0.12 MPa.

[0015] Optionally, the heating and drying process includes: S1, raising and maintaining the plate temperature at -52℃ to -48℃, with a vacuum of 20Pa to 40Pa, for 1.5 hours; S2, raising and maintaining the plate temperature at -42℃ to -38℃, with a vacuum of 20Pa to 40Pa, for 1 hour; S3, raising and maintaining the plate temperature at -32℃ to -28℃, with a vacuum of 20Pa to 40Pa, for 1 hour; S4, raising and maintaining the plate temperature at -22℃ to -18℃, with a vacuum of 20Pa to 40Pa, for 1 hour; S5, raising and maintaining the plate temperature at -12℃ to -8℃, with a vacuum of 1... S6, maintain at 0 Pa to 30 Pa for 5 hours; S7, maintain at -1℃ to 1℃ with a vacuum of 10 Pa to 30 Pa for 5 hours; S8, maintain at 19℃ to 21℃ with a vacuum of 5 Pa to 20 Pa for 5 hours; S9, maintain at 29℃ to 31℃ with a vacuum of 5 Pa to 20 Pa for 3 hours; S10, maintain at 35℃ to 40℃ with a vacuum of 0 Pa to 2 Pa for 2 hours.

[0016] Optionally, the predetermined moisture content is less than 5%.

[0017] Optionally, it also includes: after drying, filling with dry inert gas to break the vacuum, and sorting and packaging in an environment where the temperature of the Cordyceps sinensis is consistent with the ambient temperature.

[0018] According to another aspect of the present invention, a method for preparing Cordyceps sinensis is provided, comprising: spreading the cleaned Cordyceps sinensis flat in a material tray and placing it in the drying chamber of a freeze dryer; starting a compressor to cool the plates of the drying chamber, cooling the cleaned Cordyceps sinensis at a first cooling rate to a first temperature below the eutectic point, so that the water inside the Cordyceps sinensis is completely frozen to form ice crystals; performing at least one freeze-thaw cycle on the frozen Cordyceps sinensis, the freeze-thaw cycle comprising starting a heating circulation pump to raise the plate temperature to a second temperature above 0°C to thaw the frozen Cordyceps sinensis, and then starting the compressor to cool it down to the first temperature at a second cooling rate for refreezing; placing the Cordyceps sinensis after the freeze-thaw cycle treatment in a vacuum environment, and performing at least one pressure change treatment by changing the chamber pressure of the freeze dryer through a vacuum pump; turning on the heating circulation pump, and heating and drying the pressure-changed Cordyceps sinensis under vacuum conditions until a predetermined moisture content is reached.

[0019] Optionally, the pressure change process includes: evacuating and cooling the water trap while the drying chamber and water trap of the freeze dryer are isolated; opening the valve connecting the drying chamber and the water trap to bring the drying chamber to a negative pressure state and maintain it for a certain period of time; closing the valve to release the air from the drying chamber and restore it to normal pressure.

[0020] Optionally, the pressure change process includes: evacuating and cooling the water trap while the drying chamber and water trap of the freeze dryer are isolated; opening the valve connecting the drying chamber and the water trap to bring the drying chamber to a negative pressure state and maintain it for a certain period of time; closing the valve and filling the drying chamber with dry inert gas to a positive pressure state.

[0021] One embodiment of the above invention has the following advantages or beneficial effects: by cooling the cleaned Cordyceps sinensis to a first temperature below the eutectic point at a first cooling rate, the water inside the Cordyceps sinensis is completely frozen to form ice crystals; the frozen Cordyceps sinensis is subjected to at least one freeze-thaw cycle, the freeze-thaw cycle including thawing the frozen Cordyceps sinensis by raising the temperature to a second temperature above 0°C, and then refreezing it by cooling it to the first temperature at a second cooling rate; the Cordyceps sinensis after the freeze-thaw cycle is placed in a vacuum environment, and at least one pressure change is performed by changing the chamber pressure of the freeze dryer; the pressure-changed Cordyceps sinensis is heated and dried under vacuum conditions until a predetermined moisture content is reached, through ultra-low temperature pre-freezing treatment and repeated freeze-thaw cycles. The processing can induce the formation of large ice crystals inside the cordyceps, which can effectively pierce or tear cell walls and vacuolar membranes. This physically opens up channels for the release of active substances (polysaccharides, cordycepin, etc.) from the cell interior, significantly improving the dissolution rate of active substances when consumed by users (including but not limited to direct chewing, brewing, stewing, etc.) and increasing the bioavailability of cordyceps. By performing vacuum pressure treatment on cordyceps, the residual gas or vapor inside the cordyceps expands due to the reduced pressure, causing the porous network structure already formed inside the cordyceps to expand in volume. This not only accelerates the drying rate but, more importantly, creates a uniform, loose, and crisp texture, resulting in a unique melt-in-your-mouth taste and solving the problem of the hard texture and poor palatability of traditional freeze-dried cordyceps.

[0022] The further effects of the aforementioned unconventional alternative methods will be explained below in conjunction with specific implementation methods. Attached Figure Description

[0023] The accompanying drawings are provided to better understand the invention and are not intended to unduly limit the scope of the invention. Wherein: Figure 1 This is a schematic diagram of the main steps in the preparation method of Cordyceps sinensis according to an embodiment of the present invention.

[0024] Figure 2This is a schematic diagram of the main steps in the preparation method of Cordyceps sinensis according to another embodiment of the present invention. Detailed Implementation

[0025] The following description, in conjunction with the accompanying drawings, illustrates exemplary embodiments of the present invention, including various details to aid understanding. These details should be considered merely exemplary. Therefore, those skilled in the art will recognize that various changes and modifications can be made to the embodiments described herein without departing from the scope and spirit of the invention. Similarly, for clarity and brevity, descriptions of well-known functions and structures are omitted in the following description.

[0026] To address the technical problems in existing Cordyceps preparation processes, such as difficulty in extracting active ingredients, low bioavailability, and a hard texture and poor palatability after drying, this invention provides a method for preparing Cordyceps that can efficiently break down cell walls to release active substances and give Cordyceps a unique crispy texture.

[0027] Figure 1 This is a schematic diagram illustrating the main steps of a method for preparing Cordyceps sinensis according to an embodiment of the present invention. Figure 1 As shown, the preparation method of Cordyceps sinensis in this embodiment of the invention mainly includes the following steps S101 to S104.

[0028] Step S101: Cool the cleaned Cordyceps sinensis at a first cooling rate to a first temperature below the eutectic point, so that the water inside the Cordyceps sinensis is completely frozen to form ice crystals. Here, the eutectic point refers to the highest temperature at which all the water and solute in the Cordyceps sinensis material are completely frozen into a solid mixture (eutectic).

[0029] According to one embodiment of the present invention, before performing step S101, a raw material pretreatment step of Cordyceps sinensis (hereinafter also referred to as "Cordyceps") may be included. Specifically, fresh, undamaged Cordyceps sinensis can be selected, and surface mud and sand can be removed by low-temperature airflow or ultrasonic cleaning technology, followed by draining the surface moisture to obtain cleaned Cordyceps sinensis. Then, step S101 is performed to pre-freeze the Cordyceps sinensis at ultra-low temperatures to ensure that its shape remains unchanged during the drying process.

[0030] In one embodiment of the present invention, when performing ultra-low temperature pre-freezing treatment on Cordyceps, the first temperature is -70°C to -50°C, and the first cooling rate is 1°C / min to 5°C / min. Specifically, the cleaned Cordyceps is spread flat in a material tray and placed in the drying chamber (or front chamber) of a freeze dryer. The temperature of the Cordyceps is lowered to a first temperature of -70°C to -50°C (i.e., -60°C ± 10°C) at a first cooling rate of 1°C / min to 5°C / min. Here, this first temperature is much lower than the eutectic point temperature of Cordyceps during conventional freeze-drying (the eutectic point range of Cordyceps is approximately -25°C to -10°C) to ensure that the water inside the Cordyceps completely forms ice crystals. Furthermore, generally, the faster the cooling rate, the smaller the ice crystals, and the slower the cooling rate, the larger the ice crystals. Therefore, in this embodiment of the present invention, a slower cooling rate is chosen to allow larger ice crystals to form inside the cells, making it easier to pierce the cell walls and vacuolar membranes, thus providing a basis for subsequent repeated freeze-thaw treatments.

[0031] Step S102: Perform at least one freeze-thaw cycle on the frozen Cordyceps sinensis. The freeze-thaw cycle includes thawing the frozen Cordyceps sinensis by raising the temperature to a second temperature above 0°C, and then refreezing it by lowering the temperature to the first temperature at a second cooling rate. By performing freeze-thaw treatment on the frozen Cordyceps sinensis, the water inside and outside the cells can form large ice crystals during the repeated freezing and thawing process. The growth of large ice crystals has physical mechanical force, which can effectively pierce or tear the cell wall and vacuolar membrane, thereby physically opening the channel for the release of active substances (polysaccharides, cordycepin, etc.) from the inside of the cell, thus improving the bioavailability of Cordyceps sinensis.

[0032] In one embodiment of the invention, the number of freeze-thaw cycles can be, for example, 1 to 5. By increasing the number of freeze-thaw cycles, it can be ensured that the channels for the release of active substances from inside the cells are opened through the ice crystals within the cordyceps, thus guaranteeing the cell wall breaking effect. In specific implementation, if the freeze-drying equipment cannot cool the cordyceps to the optimal temperature of -60°C, -40°C or similar temperatures can be used as the initial freezing temperature, but the number of freeze-thaw cycles can be appropriately increased (e.g., 5 or 6 times) to achieve the same freeze-thaw cell wall breaking effect.

[0033] In one embodiment of the present invention, the second cooling rate is 1°C / min to 5°C / min. In specific implementation, the second cooling rate may be the same as or different from the first cooling rate, but both are relatively small cooling rates to ensure that larger ice crystals can be formed inside the cells of Cordyceps, making it easier to pierce or tear the cell walls and vacuolar membranes.

[0034] According to one embodiment of the present invention, step S102, in which the temperature is raised to a second temperature above 0°C to thaw the frozen Cordyceps sinensis, may specifically include: raising the temperature to a second temperature above 0°C at a set heating rate and maintaining it for a period of time to thaw the frozen Cordyceps sinensis. The second temperature is 20°C to 30°C, the heating rate is 1°C / min to 5°C / min, and the time period is no less than 30 minutes.

[0035] Normally, after cordyceps is heated to a second temperature above 0°C, the frozen ice crystals inside the cordyceps begin to melt. This invention sets the heating rate to 1°C / min to 5°C / min, which prevents the cordyceps structure from being damaged or melted during the ice crystal melting process, preventing the deactivation of heat-sensitive components and greatly preserving the efficacy of the prepared cordyceps. This invention raises the temperature to a second temperature of 20°C to 30°C, which not only increases the melting speed of the ice crystals for more efficient cordyceps preparation, but also avoids the loss of effective substances (such as cordycepin, adenosine, polysaccharides, and other heat-sensitive active ingredients) caused by excessively high temperatures, thus preserving the medicinal value of cordyceps to a great extent. When thawing cordyceps, the second temperature can be maintained for at least 30 minutes to ensure that the cordyceps is completely thawed, guaranteeing the freeze-thaw cell wall breaking effect.

[0036] In practice, after the cordyceps undergoes ultra-low temperature pre-freezing treatment in step S101, it will be subjected to 1 to 5 freeze-thaw cycles. During each freeze-thaw cycle, the temperature of the freeze dryer's plates can be raised to a second temperature of 20 to 30°C at a heating rate of 1°C / min to 5°C / min, and maintained for at least 30 minutes to completely thaw the cordyceps. Subsequently, the temperature is lowered to -60°C ± 10°C at a second cooling rate of 1°C / min to 5°C / min.

[0037] During this process, due to the huge temperature difference (>50℃), the water inside and outside the cells repeatedly freezes and thaws, forming large ice crystals. The growth of these large ice crystals has physical and mechanical force, which can effectively pierce or tear the cell wall and vacuolar membrane, thereby physically opening up the channels for the release of active substances from the inside of the cell and improving the bioavailability of cordyceps.

[0038] Step S103: Place the Cordyceps sinensis, after freeze-thaw cycle treatment, in a vacuum environment and perform at least one pressure-switching process by changing the chamber pressure of the freeze dryer. After freeze-thaw cycle treatment, place the Cordyceps sinensis in a vacuum environment and perform pressure-switching treatment. The residual gas or vapor inside the Cordyceps sinensis expands in volume due to the pressure reduction, which can produce an expansion effect similar to the "popcorn effect" in the porous network structure already formed inside the Cordyceps sinensis. This further expands the intercellular gaps and tissue structure torn by ice crystals, ultimately forming a uniform, loose, and crisp microstructure, thus bringing a unique melt-in-your-mouth texture.

[0039] According to one embodiment of the present invention, during pressure transformation, the pressure can be switched between atmospheric pressure and a negative pressure below atmospheric pressure. Specifically, the pressure transformation includes: reducing the chamber pressure to a negative pressure state below atmospheric pressure and maintaining it for a certain period of time, and then restoring it to an atmospheric pressure state.

[0040] In embodiments of the present invention, the pressure under negative pressure is, for example, 0.05 MPa (i.e., 0.5 atmospheres), and the time period is, for example, 10 to 30 minutes. In other embodiments, the pressure under negative pressure can also be 0.03 MPa (i.e., 0.3 atmospheres) or 0.07 MPa (i.e., 0.7 atmospheres), and the degree of expansion is controlled by adjusting the pressure difference. Specifically, if the pressure under negative pressure is 0.5 atmospheres, the vacuum level of the rear chamber needs to be approximately 0 atmospheres (e.g., 0-50 Pa) before vacuuming; if the pressure under negative pressure is 0.3 atmospheres, the drying chamber needs to be vacuumed before opening the valve connecting the drying chamber (front chamber) and the water trap (rear chamber) to achieve a pressure of 0.6 atmospheres; if the pressure under negative pressure is 0.7 atmospheres, the rear chamber needs to be vacuumed to achieve a pressure of 0.4 atmospheres.

[0041] According to another embodiment of the present invention, during the pressure transformation process, a bidirectional pulse method can be used to switch between a positive pressure above atmospheric pressure and a negative pressure below atmospheric pressure, utilizing the alternation of positive and negative pressure to generate an expansion effect. Specifically, the pressure transformation process includes: reducing the chamber pressure to a negative pressure state below atmospheric pressure and maintaining it for a certain period of time, and then filling it with dry inert gas to a positive pressure state. The negative pressure state is, for example, 0.05 MPa (i.e., 0.5 atmospheres), the certain period of time is, for example, 10 to 30 minutes, and the positive pressure state is 0.12 MPa (i.e., 1.2 atmospheres). In specific implementations, the positive pressure state is not limited to 0.12 MPa and can also be other pressure values.

[0042] According to one embodiment of the present invention, the number of pressure treatments is, for example, 1 to 5 times. In this way, the expansion and crisping effect on the cordyceps can be adjusted by changing the number of pressure treatments, so that the prepared cordyceps has a crisp texture and improved palatability.

[0043] In practice, after the cordyceps undergoes freeze-thaw cycles in step S102, it will be subjected to one to five pressure-swapping treatments to vacuum expand and soften it. Each pressure-swapping treatment can be performed in the following order: 1. Turn on the compressor of the freeze dryer to cool the water trap (rear compartment) until its temperature reaches -60℃ to -80℃; 2. Start the vacuum pump to evacuate the rear chamber until the vacuum level reaches 0-50 Pa; 3. Open the valve (intermediate valve or large disc valve) connecting the front and rear compartments to bring the front compartment to a negative pressure of 0.05 MPa instantly and maintain it for 10 to 30 minutes; 4. Close the valve, and then open the vent valve to bring the front chamber to normal pressure.

[0044] According to this embodiment, a drastic pressure change from normal to low pressure creates an expansion effect similar to the "popcorn effect" within the porous network structure already formed inside the cordyceps. This expansion further expands the intercellular spaces and tissue structure torn apart by ice crystals, ultimately forming a uniform, loose, and crisp microstructure, resulting in a unique melt-in-your-mouth texture.

[0045] Step S104: The Cordyceps sinensis that has undergone pressure swing treatment is heated and dried under vacuum conditions until a predetermined moisture content is reached. During the heating and drying process, a gradient heating can be performed under vacuum conditions to gradually raise the plate temperature to 30°C to 40°C, thereby desorption and drying the Cordyceps sinensis to remove bound water tightly bound to the material until the Cordyceps sinensis reaches a predetermined moisture content, which is less than 5%.

[0046] According to one embodiment of the present invention, the heating and drying process mainly includes the following steps: S1, the plate temperature rises and is maintained at -52℃ to -48℃, the vacuum degree is 20Pa to 40Pa, and is maintained for 1.5 hours; S2, the plate temperature rises and is maintained at -42℃ to -38℃, the vacuum degree is 20Pa to 40Pa, and is maintained for 1 hour; S3, the plate temperature rises and is maintained at -32℃ to -28℃, the vacuum degree is 20Pa to 40Pa, and is maintained for 1 hour; S4, the plate temperature rises and is maintained at -22℃ to -18℃, the vacuum degree is 20Pa to 40Pa, and is maintained for 1 hour; S5, the plate temperature rises and is maintained at -12℃ to -8℃, the vacuum degree is 10Pa to 30Pa, and is maintained for 5 hours; S6, the plate temperature rises and is maintained at -1℃ to 1℃, the vacuum degree is 10Pa to 30Pa, and is maintained for 5 hours; S7, the plate temperature rises and is maintained at 9℃-11℃, the vacuum degree is 10Pa-30Pa, and it is maintained for 5 hours; S8, the plate temperature rises and is maintained at 19℃-21℃, the vacuum degree is 5Pa-20Pa, and it is maintained for 5 hours; S9, the plate temperature rises and is maintained at 29℃-31℃, the vacuum degree is 5Pa-20Pa, and it is maintained for 3 hours; S10, the plate temperature rises and is maintained at 35℃-40℃, the vacuum degree is 0Pa-2Pa, and it is maintained for 2 hours.

[0047] By gradually raising the temperature of the plate to 30°C to 40°C in a vacuum environment, the cordyceps can be decomposed and dried, removing the bound water that is tightly bound to the cordyceps material until the moisture content of the cordyceps is less than 5%.

[0048] According to other embodiments of the present invention, the method for preparing Cordyceps sinensis can further include breaking the vacuum by filling with dry inert gas after drying, and sorting and packaging the Cordyceps sinensis in an environment where the temperature is consistent with the ambient temperature. Specifically, after freeze-drying the Cordyceps sinensis, dry and sterile inert gas (such as nitrogen) or dry air can be filled into the front chamber of the freeze dryer to break the vacuum and prevent humid air from entering and causing the product to absorb moisture. Then, after the temperature of the Cordyceps sinensis is adjusted to be consistent with the ambient temperature, sorting and packaging are carried out.

[0049] The following describes the specific implementation process of the preparation method of Cordyceps sinensis according to the present invention, with reference to several specific embodiments.

[0050] Example 1

[0051] The preparation method of this Cordyceps sinensis mainly includes the following steps: Step 1: Select fresh, undamaged Cordyceps sinensis, use low-temperature airflow cleaning technology to remove surface dirt and sand, and drain the surface moisture; Step 2: Cool the cleaned Cordyceps sinensis to -60℃ at a cooling rate of 1℃ / min, so that the water inside the Cordyceps sinensis is completely frozen to form ice crystals. Step 3: Perform three freeze-thaw cycles on the frozen Cordyceps sinensis. The freeze-thaw cycle includes raising the temperature to 25°C at a rate of 3°C / min, holding it for 30 minutes to completely thaw the frozen Cordyceps sinensis, and then lowering the temperature to -60°C at a rate of 1°C / min for refreezing. Step 4: Place the Cordyceps sinensis that has undergone freeze-thaw cycle treatment in a vacuum environment and perform three pressure-changing treatments by changing the chamber pressure of the freeze dryer. The pressure-changing treatment includes reducing the chamber pressure to half an atmosphere and maintaining it for 20 minutes, and then restoring it to normal pressure. Step 5: Under vacuum conditions, the Cordyceps sinensis that has undergone pressure swing treatment is subjected to the following temperature drying process until the moisture content of the Cordyceps sinensis is below 5%: S1, the plate temperature rises and is maintained at -50℃, the vacuum degree is 20Pa-40Pa, and it is maintained for 1.5 hours; S2, the plate temperature rises and is maintained at -40℃, the vacuum degree is 20Pa-40Pa, and it is maintained for 1 hour; S3, the plate temperature rises and is maintained at -30℃, the vacuum degree is 20Pa-40Pa, and it is maintained for 1 hour; S4, the plate temperature rises and is maintained at -20℃, the vacuum degree is 20Pa-40Pa, and it is maintained for 1 hour; S5, the plate temperature rises and is maintained at -10℃, the vacuum degree is 10Pa-30Pa, and it is maintained for 5 hours; S6, the plate temperature rises and is maintained at 0℃, the vacuum degree is 10Pa-30Pa, and it is maintained for 5 hours; S7, the plate temperature rises and is maintained at 10℃, the vacuum degree is 10Pa-30Pa, and it is maintained for 5 hours; S8, the plate temperature rises and is maintained at 20°C, the vacuum degree is 5Pa-20Pa, and it is maintained for 5 hours; S9, the plate temperature rises and is maintained at 30°C, the vacuum degree is 5Pa-20Pa, and it is maintained for 3 hours; S10, the plate temperature rises and is maintained at 40℃, the vacuum degree is 0Pa-2Pa, and it is maintained for 2 hours.

[0052] Ultimately, one can obtain cordyceps with a crisp texture and high bioavailability.

[0053] Example 2

[0054] The preparation method of this Cordyceps sinensis mainly includes the following steps: Step 1: Select fresh, undamaged cordyceps, use ultrasonic cleaning technology to remove surface dirt and sand, and drain the surface moisture. Step 2: Cool the cleaned Cordyceps sinensis to -50℃ at a cooling rate of 3℃ / min, so that the water inside the Cordyceps sinensis is completely frozen to form ice crystals. Step 3: Perform 5 freeze-thaw cycles on the frozen Cordyceps sinensis. The freeze-thaw cycle includes raising the temperature to 30°C at a heating rate of 1°C / min, holding it for 40 minutes to completely thaw the frozen Cordyceps sinensis, and then lowering the temperature to -50°C at a cooling rate of 3°C / min to refreeze it. Step 4: Place the Cordyceps sinensis that has undergone freeze-thaw cycle treatment in a vacuum environment and perform five pressure-changing treatments by changing the chamber pressure of the freeze dryer. The pressure-changing treatment includes reducing the chamber pressure to 0.7 atmospheres and maintaining it for 30 minutes, and then restoring it to normal pressure. Step 5: Under vacuum conditions, the Cordyceps sinensis that has undergone pressure swing treatment is subjected to the following temperature drying process until the moisture content of the Cordyceps sinensis is below 5%: S1, the plate temperature rises and is maintained at -52℃, the vacuum degree is 20Pa-40Pa, and it is maintained for 1.5 hours; S2, the plate temperature rises and is maintained at -42℃, the vacuum degree is 20Pa-40Pa, and it is maintained for 1 hour; S3, the plate temperature rises and is maintained at -32℃, the vacuum degree is 20Pa-40Pa, and it is maintained for 1 hour; S4, the plate temperature rises and is maintained at -22℃, the vacuum degree is 20Pa-40Pa, and it is maintained for 1 hour; S5, the plate temperature rises and is maintained at -12℃, the vacuum degree is 10Pa-30Pa, and it is maintained for 5 hours; S6, the plate temperature rises and is maintained at -1℃, the vacuum degree is 10Pa-30Pa, and it is maintained for 5 hours; S7, the plate temperature rises and is maintained at 9°C, the vacuum degree is 10Pa-30Pa, and it is maintained for 5 hours; S8, the plate temperature rises and is maintained at 19°C, the vacuum degree is 5Pa-20Pa, and it is maintained for 5 hours; S9, the plate temperature rises and is maintained at 29°C, the vacuum degree is 5Pa-20Pa, and it is maintained for 3 hours; S10, the plate temperature rises and is maintained at 35°C, the vacuum degree is 0Pa-2Pa, and it is maintained for 2 hours.

[0055] Ultimately, one can obtain cordyceps with a crisp texture and high bioavailability.

[0056] Example 3

[0057] The difference between this embodiment and Embodiment 1 is that: Step 2: Cool the cleaned Cordyceps sinensis to -70℃ at a cooling rate of 5℃ / min, so that the water inside the Cordyceps sinensis is completely frozen to form ice crystals. Step 3: Perform one freeze-thaw cycle on the frozen Cordyceps sinensis. The freeze-thaw cycle includes raising the temperature to 20°C at a heating rate of 5°C / min, holding it for 50 minutes to completely thaw the frozen Cordyceps sinensis, and then lowering the temperature to -70°C at a cooling rate of 3°C / min for refreezing.

[0058] Ultimately, one can obtain cordyceps with a crisp texture and high bioavailability.

[0059] Example 4

[0060] The difference between this embodiment and Embodiment 1 is that: Step 4: Place the Cordyceps sinensis that has undergone freeze-thaw cycle treatment in a vacuum environment and perform a pressure change treatment by changing the chamber pressure of the freeze dryer. The pressure change treatment includes reducing the chamber pressure to 0.3 atmospheres and maintaining it for 10 minutes, and then restoring it to normal pressure.

[0061] Ultimately, one can obtain cordyceps with a crisp texture and high bioavailability.

[0062] Example 5

[0063] The difference between this embodiment and Embodiment 1 is that: Step 4: Place the Cordyceps sinensis that has undergone freeze-thaw cycle treatment in a vacuum environment and perform three pressure-changing treatments by changing the chamber pressure of the freeze dryer. The pressure-changing treatments include reducing the chamber pressure to half an atmosphere and maintaining it for 20 minutes, and then filling it with dry inert gas to 1.2 atmospheres.

[0064] Ultimately, one can obtain cordyceps with a crisp texture and high bioavailability.

[0065] Example 6

[0066] The difference between this embodiment and Embodiment 1 is that: Step 4: Place the Cordyceps sinensis that has undergone freeze-thaw cycle treatment in a vacuum environment and perform five pressure-changing treatments by changing the chamber pressure of the freeze dryer. The pressure-changing treatments include reducing the chamber pressure to 0.7 atmospheres and maintaining it for 25 minutes, and then filling it with dry inert gas to 1.2 atmospheres.

[0067] Ultimately, one can obtain cordyceps with a crisp texture and high bioavailability.

[0068] Example 7

[0069] The difference between this embodiment and Embodiment 1 is that: Step 4: Place the Cordyceps sinensis that has undergone freeze-thaw cycle treatment in a vacuum environment and perform two pressure-switching treatments by changing the chamber pressure of the freeze dryer. The pressure-switching treatment includes reducing the chamber pressure to 0.3 atmospheres and maintaining it for 20 minutes, and then filling it with dry inert gas to 1.2 atmospheres.

[0070] Ultimately, one can obtain cordyceps with a crisp texture and high bioavailability.

[0071] Example 8

[0072] The difference between this embodiment and Embodiment 1 is that: Step 5: Under vacuum conditions, the Cordyceps sinensis that has undergone pressure swing treatment is subjected to the following temperature drying process until the moisture content of the Cordyceps sinensis is below 5%: S1, the plate temperature rises and is maintained at -48℃, the vacuum degree is 20Pa-40Pa, and it is maintained for 1.5 hours; S2, the plate temperature rises and is maintained at -38℃, the vacuum degree is 20Pa-40Pa, and it is maintained for 1 hour; S3, the plate temperature rises and is maintained at -28℃, the vacuum degree is 20Pa-40Pa, and it is maintained for 1 hour; S4, the plate temperature rises and is maintained at -18℃, the vacuum degree is 20Pa-40Pa, and it is maintained for 1 hour; S5, the plate temperature rises and is maintained at -8℃, the vacuum degree is 10Pa-30Pa, and it is maintained for 5 hours; S6, the plate temperature rises and is maintained at 1℃, the vacuum degree is 10Pa-30Pa, and it is maintained for 5 hours; S7, the plate temperature rises and is maintained at 11℃, the vacuum degree is 10Pa-30Pa, and it is maintained for 5 hours; S8, the plate temperature rises and is maintained at 21°C, the vacuum degree is 5Pa-20Pa, and it is maintained for 5 hours; S9, the plate temperature rises and is maintained at 31°C, the vacuum degree is 5Pa-20Pa, and it is maintained for 3 hours; S10, the plate temperature rises and is maintained at 38°C, the vacuum degree is 0Pa-2Pa, and it is maintained for 2 hours.

[0073] Ultimately, one can obtain cordyceps with a crisp texture and high bioavailability.

[0074] Example 9

[0075] The difference between this embodiment and Embodiment 1 is that it also includes: Step 6: After drying, fill the vacuum with dry inert gas and sort and package the Cordyceps sinensis in an environment where the temperature is consistent with the ambient temperature.

[0076] Ultimately, one can obtain cordyceps with a crisp texture and high bioavailability.

[0077] Figure 2 This is a schematic diagram illustrating the main steps of a method for preparing Cordyceps sinensis according to another embodiment of the present invention. Figure 2 As shown, this embodiment describes the preparation method of Cordyceps sinensis from the perspective of operating the freeze dryer equipment, which mainly includes the following steps S201 to S205.

[0078] Step S201: Spread the cleaned Cordyceps sinensis flat in a material tray and place it in the drying chamber of the freeze dryer; Step S202: Start the compressor to cool the drying chamber plates, cool the cleaned Cordyceps sinensis to a first temperature below the eutectic point at the first cooling rate, so that the water inside the Cordyceps sinensis is completely frozen to form ice crystals. Step S203: Perform at least one freeze-thaw cycle on the frozen Cordyceps sinensis. The freeze-thaw cycle includes starting the heating circulation pump to raise the plate temperature to a second temperature above 0°C to thaw the frozen Cordyceps sinensis, and then starting the compressor to cool it down to the first temperature at a second cooling rate for refreezing. Step S204: Place the Cordyceps sinensis that has undergone freeze-thaw cycle treatment in a vacuum environment, and perform at least one pressure change treatment by changing the chamber pressure of the freeze dryer through a vacuum pump. Step S205: Turn on the heating circulation pump and heat and dry the Cordyceps sinensis that has undergone pressure swing treatment under vacuum conditions until the predetermined moisture content is reached.

[0079] According to an embodiment of the present invention, step S204, when performing the pressure transformation process, specifically includes: evacuating and cooling the water trap while the drying chamber and the water trap of the freeze dryer are isolated; opening the valve connecting the drying chamber and the water trap to bring the drying chamber to a negative pressure state and maintain it for a certain period of time; closing the valve and releasing the air from the drying chamber to restore it to normal pressure.

[0080] According to an embodiment of the present invention, step S204, when performing pressure transformation, specifically includes: evacuating and cooling the water trap while the drying chamber and the water trap of the freeze dryer are isolated; opening the valve connecting the drying chamber and the water trap to bring the drying chamber to a negative pressure state and maintain it for a certain period of time; closing the valve and filling the drying chamber with dry inert gas to a positive pressure state.

[0081] The preparation method of Cordyceps sinensis according to the present invention is described below with reference to specific embodiments.

[0082] Example 10

[0083] The preparation method of this Cordyceps sinensis mainly includes the following steps: Step 1: Select fresh, undamaged Cordyceps sinensis, use low-temperature airflow cleaning technology to remove surface dirt and sand, and drain the surface moisture; Step 2: Spread the cleaned cordyceps sinensis evenly in the material tray, put it into the drying chamber of the freeze dryer, and close the chamber door; Step 3: Start the compressor to cool the drying chamber and cool the cleaned Cordyceps sinensis to -60℃ at a cooling rate of 1℃ / min, so that the water inside the Cordyceps sinensis is completely frozen to form ice crystals. Step 4: Perform three freeze-thaw cycles on the frozen Cordyceps sinensis. The freeze-thaw cycle includes starting the heating circulation pump, raising the temperature to 25°C at a heating rate of 3°C / min, maintaining it for 30 minutes to completely thaw the frozen Cordyceps sinensis, turning off the heating circulation pump, and then starting the compressor to cool the temperature to -60°C at a cooling rate of 1°C / min for refreezing. Step 5: Place the Cordyceps sinensis that has undergone freeze-thaw cycle treatment in a vacuum environment. Use a vacuum pump to change the chamber pressure of the freeze dryer three times. The pressure change process includes: with the drying chamber and water trap in an isolated state, use a compressor to cool the water trap to a temperature of -60°C, and use a vacuum pump to evacuate the water trap to a vacuum degree of 40 Pa; then, open the valve connecting the drying chamber and the water trap to allow the drying chamber to reach half atmosphere pressure and maintain it for 20 minutes; close the valve and release the air from the drying chamber to restore it to normal pressure. Step 6: Turn on the heating circulation pump and perform the following temperature-drying treatment on the Cordyceps sinensis under vacuum conditions until the moisture content of the Cordyceps sinensis is below 5%: S1, the plate temperature rises and is maintained at -50℃, the vacuum degree is 20Pa-40Pa, and it is maintained for 1.5 hours; S2, the plate temperature rises and is maintained at -40℃, the vacuum degree is 20Pa-40Pa, and it is maintained for 1 hour; S3, the plate temperature rises and is maintained at -30℃, the vacuum degree is 20Pa-40Pa, and it is maintained for 1 hour; S4, the plate temperature rises and is maintained at -20℃, the vacuum degree is 20Pa-40Pa, and it is maintained for 1 hour; S5, the plate temperature rises and is maintained at -10℃, the vacuum degree is 10Pa-30Pa, and it is maintained for 5 hours; S6, the plate temperature rises and is maintained at 0℃, the vacuum degree is 10Pa-30Pa, and it is maintained for 5 hours; S7, the plate temperature rises and is maintained at 10℃, the vacuum degree is 10Pa-30Pa, and it is maintained for 5 hours; S8, the plate temperature rises and is maintained at 20°C, the vacuum degree is 5Pa-20Pa, and it is maintained for 5 hours; S9, the plate temperature rises and is maintained at 30°C, the vacuum degree is 5Pa-20Pa, and it is maintained for 3 hours; S10, the plate temperature rises and is maintained at 40℃, the vacuum degree is 0Pa-2Pa, and it is maintained for 2 hours.

[0084] Ultimately, one can obtain cordyceps with a crisp texture and high bioavailability.

[0085] Example 11

[0086] The difference between this embodiment and embodiment 10 is that: Step 5: Place the Cordyceps sinensis that has undergone freeze-thaw cycle treatment in a vacuum environment. Use a vacuum pump to change the chamber pressure of the freeze dryer five times. The pressure change process includes: with the drying chamber and water trap of the freeze dryer isolated, use a compressor to cool the water trap to a temperature of -70°C, and use a vacuum pump to evacuate the water trap to a vacuum level of 0.4 atmospheres; then, open the valve connecting the drying chamber and the water trap to allow the drying chamber to reach a pressure of 0.7 atmospheres and maintain it for 25 minutes; close the valve and release the air from the drying chamber to restore it to normal pressure.

[0087] Ultimately, one can obtain cordyceps with a crisp texture and high bioavailability.

[0088] Example 12

[0089] The difference between this embodiment and embodiment 10 is that: Step 5: Place the Cordyceps sinensis that has undergone freeze-thaw cycle treatment in a vacuum environment. Use a vacuum pump to change the chamber pressure of the freeze dryer for one pressure change process. The pressure change process includes: with the drying chamber and water trap of the freeze dryer isolated, use a compressor to cool the water trap to a temperature of -70°C, use a vacuum pump to evacuate the water trap to a vacuum degree of 20Pa, and use a vacuum pump to evacuate the drying chamber to a vacuum degree of 0.6 atmospheres; then, open the valve connecting the drying chamber and the water trap, allowing the drying chamber to reach a pressure of 0.3 atmospheres and maintain it for 20 minutes; close the valve and release the air from the drying chamber to restore it to normal pressure.

[0090] Ultimately, one can obtain cordyceps with a crisp texture and high bioavailability.

[0091] Example 13

[0092] The difference between this embodiment and embodiment 10 is that: Step 5: Place the Cordyceps sinensis that has undergone freeze-thaw cycle treatment in a vacuum environment. Use a vacuum pump to change the chamber pressure of the freeze dryer five times. The pressure change process includes: with the drying chamber and water trap of the freeze dryer isolated, use a compressor to cool the water trap to a temperature of -80°C, and use a vacuum pump to evacuate the water trap to a vacuum level of 0.4 atmospheres; then, open the valve connecting the drying chamber and the water trap, allowing the drying chamber to reach a pressure of 0.7 atmospheres and maintain it for 25 minutes; close the valve and fill the drying chamber with dry inert gas to a pressure of 1.2 atmospheres.

[0093] Ultimately, one can obtain cordyceps with a crisp texture and high bioavailability.

[0094] According to the technical solution of this embodiment of the invention, the cleaned Cordyceps sinensis is cooled to a first temperature below the eutectic point at a first cooling rate, causing the internal moisture of the Cordyceps sinensis to completely freeze and form ice crystals; the frozen Cordyceps sinensis is subjected to at least one freeze-thaw cycle, which includes thawing the frozen Cordyceps sinensis by raising the temperature to a second temperature above 0°C, and then refreezing it by cooling it to the first temperature at a second cooling rate; the Cordyceps sinensis after the freeze-thaw cycle is placed in a vacuum environment, and at least one pressure-switching process is performed by changing the chamber pressure of a freeze dryer; the pressure-switched Cordyceps sinensis is heated and dried under vacuum conditions until a predetermined moisture content is reached, thereby achieving ultra-low temperature pre-freezing of the Cordyceps sinensis. Processing and repeated freeze-thaw cycles can induce the formation of large ice crystals inside the cordyceps, which can effectively pierce or tear cell walls and vacuolar membranes. This physically opens up channels for the release of active substances (polysaccharides, cordycepin, etc.) from inside the cells, significantly improving the dissolution rate of active substances when consumed by users and enhancing the bioavailability of cordyceps. By subjecting cordyceps to vacuum pressure treatment, the residual gas or vapor inside the cordyceps expands due to the reduced pressure. This causes the porous network structure already formed inside the cordyceps to expand, which not only accelerates the drying rate but, more importantly, creates a uniform, loose, and crisp texture, resulting in a unique melt-in-your-mouth taste. This solves the problem of traditional freeze-dried cordyceps having a hard texture and poor palatability.

[0095] The specific embodiments described above do not constitute a limitation on the scope of protection of this invention. Those skilled in the art should understand that various modifications, combinations, sub-combinations, and substitutions can occur depending on design requirements and other factors. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of this invention should be included within the scope of protection of this invention.

Claims

1. A method for preparing Cordyceps sinensis, characterized in that, include: The cleaned Cordyceps sinensis is cooled to a first temperature below the eutectic point at a first cooling rate, so that the water inside the Cordyceps sinensis is completely frozen to form ice crystals. The frozen cordyceps sinensis is subjected to at least one freeze-thaw cycle, wherein the freeze-thaw cycle includes thawing the frozen cordyceps sinensis by raising the temperature to a second temperature above 0°C, and then cooling it to the first temperature at a second cooling rate for refreezing. After undergoing freeze-thaw cycles, Cordyceps sinensis is placed in a vacuum environment and subjected to at least one pressure-changing process by altering the chamber pressure of the freeze dryer. Cordyceps sinensis that has undergone pressure swing treatment is dried under vacuum conditions until it reaches the predetermined moisture content.

2. The preparation method according to claim 1, characterized in that, The number of freeze-thaw cycles and the number of pressure-changing treatments are both 1 to 5 times.

3. The preparation method according to claim 1, characterized in that, The first temperature is -70°C to -50°C, and both the first cooling rate and the second cooling rate are 1°C / min to 5°C / min.

4. The preparation method according to claim 1, characterized in that, The second temperature, raised to above 0°C, used to thaw the frozen Cordyceps sinensis includes: The temperature is raised to a second temperature above 0°C at a set heating rate and maintained for a period of time to thaw the frozen Cordyceps sinensis.

5. The preparation method according to claim 4, characterized in that, The second temperature is 20°C to 30°C, the heating rate is 1°C / min to 5°C / min, and the time period is not less than 30 minutes.

6. The preparation method according to claim 1, characterized in that, The transformer process includes: The chamber pressure is reduced to a negative pressure state below normal pressure and maintained for a certain period of time before being restored to normal pressure.

7. The preparation method according to claim 1, characterized in that, The transformer process includes: The chamber pressure is reduced to a negative pressure state below atmospheric pressure and maintained for a certain period of time, and then restored to a positive pressure state by filling it with dry inert gas.

8. The preparation method according to claim 6 or 7, characterized in that, The pressure under negative pressure is 0.05 MPa, and the specified time is 10 to 30 minutes.

9. The preparation method according to claim 7, characterized in that, The pressure under the positive pressure state is 0.12 MPa.

10. The preparation method according to claim 1, characterized in that, The heating and drying process includes: S1, the plate temperature rises and is maintained at -52℃ to -48℃, the vacuum degree is 20Pa to 40Pa, and is maintained for 1.5 hours; S2, the plate temperature rises and is maintained at -42℃ to -38℃, the vacuum degree is 20Pa to 40Pa, and is maintained for 1 hour; S3, the plate temperature rises and is maintained at -32℃ to -28℃, the vacuum degree is 20Pa to 40Pa, and is maintained for 1 hour; S4, the plate temperature rises and is maintained at -22℃ to -18℃, the vacuum degree is 20Pa to 40Pa, and is maintained for 1 hour; S5, the plate temperature rises and is maintained at -12℃ to -8℃, the vacuum degree is 10Pa to 30Pa, and is maintained for 5 hours; S6, the plate temperature rises and is maintained at -1℃ to 1℃, the vacuum degree is 10Pa to 30Pa, and is maintained for 5 hours; S7, the plate temperature rises and is maintained at 9℃-11℃, the vacuum degree is 10Pa-30Pa, and it is maintained for 5 hours; S8, the plate temperature rises and is maintained at 19℃-21℃, the vacuum degree is 5Pa-20Pa, and it is maintained for 5 hours; S9, the plate temperature rises and is maintained at 29℃-31℃, the vacuum degree is 5Pa-20Pa, and it is maintained for 3 hours; S10, the plate temperature rises and is maintained at 35℃-40℃, the vacuum degree is 0Pa-2Pa, and it is maintained for 2 hours.

11. The preparation method according to claim 1, characterized in that, The predetermined moisture content is less than 5%.

12. The preparation method according to claim 1, characterized in that, Also includes: After drying, the cordyceps are filled with dry inert gas to break the vacuum, and then sorted and packaged in an environment where the temperature of the cordyceps is consistent with the ambient temperature.

13. A method for preparing Cordyceps sinensis, characterized in that, include: After cleaning, the cordyceps sinensis is spread flat in a material tray and placed in the drying chamber of the freeze dryer. The compressor is started to cool the drying chamber, and the cleaned Cordyceps sinensis is cooled to a first temperature below the eutectic point at a first cooling rate, so that the water inside the Cordyceps sinensis is completely frozen to form ice crystals. The frozen Cordyceps sinensis is subjected to at least one freeze-thaw cycle, the freeze-thaw cycle including starting the heating circulation pump to raise the plate temperature to a second temperature above 0°C to thaw the frozen Cordyceps sinensis, and then starting the compressor to cool it down to the first temperature at a second cooling rate for refreezing. After undergoing freeze-thaw cycles, Cordyceps sinensis is placed in a vacuum environment, and the pressure in the freeze dryer is changed at least once by a vacuum pump. Turn on the heating circulation pump and heat and dry the Cordyceps sinensis that has undergone pressure swing treatment under vacuum conditions until the predetermined moisture content is reached.

14. The preparation method according to claim 13, characterized in that, The transformer process includes: With the drying chamber and water trap of the freeze dryer isolated, the water trap is evacuated and cooled. Open the valve connecting the drying chamber and the water trap to bring the drying chamber into a negative pressure state and maintain it for a certain period of time; Close the valve and release the air from the drying chamber to restore it to normal pressure.

15. The preparation method according to claim 13, characterized in that, The transformer process includes: With the drying chamber and water trap of the freeze dryer isolated, the water trap is evacuated and cooled. Open the valve connecting the drying chamber and the water trap to bring the drying chamber into a negative pressure state and maintain it for a certain period of time; Close the valve and fill the drying chamber with dry inert gas until it reaches a positive pressure.

Images