Processing method of freeze-dried fresh-locked gastrodia elata f.glauca

Abstract

The invention discloses a processing method of freeze-dried fresh-locked gastrodia elata f.glauca and particularly relates to the technical field of processing of gastrodia elata f.glauca. The processing method comprises the following steps: S1, selecting raw materials; s2, cleaning and grading; s3, performing steaming treatment; s4, quick-freezing and forming; and S5, vacuum drying. The raw materials are strictly screened, only zero-generation or first-generation gastrodia elata fruits are selected, the size of the fruits is controlled, and a good foundation is laid for product quality. According to the cleaning and grading links, impurities are effectively removed, ozone sterilization and sterile cold air drying are utilized, microorganisms are reduced, moisture residues are prevented, in the subsequent steaming, quick-freezing and vacuum drying processes, time, temperature, pressure and other parameters are accurately controlled, the cell structure of the gastrodia elata f.glauca is protected, a large number of nutritional ingredients are reserved, and the quality of the gastrodia elata f.glauca is improved. And the original flavor is maintained to the greatest extent. All the steps are tightly matched, efficient freshness locking is achieved, consumers can taste products close to fresh gastrodia elata f.glauca, and the requirement for high-quality gastrodia elata f.glauca products is met.

Description

Technical Field

[0001] The present invention relates to the technical field of Gastrodia elata processing, and particularly to a processing method for freeze-dried and freshness-locked Gastrodia elata. Background Art

[0002] Gastrodia elata is a traditional Chinese medicine with high medicinal and nutritional value, rich in various beneficial components to the human body such as gastrodin and polysaccharides, and is widely used in the field of medical care. In traditional processing methods, the effective components of Gastrodia elata are often lost due to improper handling, the taste becomes worse, and it is difficult to maintain its freshness and quality for a long time. Although there are some existing drying methods, due to the limitations of processing technology, it is impossible to well retain the original flavor, nutritional components and appearance of Gastrodia elata. In the market, there is a lack of a processing method that can efficiently lock freshness and maximize the retention of the original characteristics of Gastrodia elata, which restricts the quality improvement and market expansion of Gastrodia elata products. This not only affects consumers' willingness to buy, but also hinders the further development of the Gastrodia elata industry, making it difficult for Gastrodia elata to stand out in the market competition and unable to fully exert its due economic value and social value. Summary of the Invention

[0003] The main purpose of the present invention is to provide a processing method for freeze-dried and freshness-locked Gastrodia elata, which can effectively solve the problems mentioned in the background art.

[0004] To achieve the above purpose, the technical solution adopted by the present invention is as follows:

[0005] A processing method for freeze-dried and freshness-locked Gastrodia elata includes the following steps:

[0006] S1: Raw material selection, select the zero-generation or first-generation fruits of Gastrodia elata, and ensure that the fruit length is within 5 cm and the fruit diameter is within 3 cm;

[0007] S2: Cleaning and grading, clean the selected Gastrodia elata to remove surface impurities, and perform grading treatment according to size, shape, etc.;

[0008] S3: Steaming treatment, put the cleaned and graded Gastrodia elata into a steamer, and steam for 5 - 10 minutes after the water boils until it is cooked;

[0009] S4: Quick freezing and forming, place the cooked Gastrodia elata on a freezing tray, and then put it into a freezer at a temperature of -30 - -40 degrees for quick freezing to make it form;

[0010] S5: Vacuum drying, put the quick-frozen and formed Gastrodia elata into a freeze dryer, and perform vacuum drying for 36 - 48 hours in a negative pressure environment, and control the temperature at 30 - 40 degrees during the drying process.

[0011] Preferably, in S2, when cleaning the black Gastrodia elata, it is rinsed with flowing clean water for 3 minutes. When grading, according to the weight difference of the black Gastrodia elata, it is divided into three grades: light, medium, and heavy. Among them, the weight range of the light grade is 10-20g, the weight range of the medium grade is 26-30g, and the weight range of the heavy grade is 34-38g.

[0012] Preferably, after cleaning and grading in S2, the black Gastrodia elata of different grades are respectively placed in an environment with an ozone concentration of 5mg / m 3 for 10 minutes of sterilization treatment. After the treatment, the surface moisture of the black Gastrodia elata is quickly dried with sterile cold air, with a wind speed of 3m / s and a time of 5 minutes.

[0013] Preferably, in S3, when steaming the black Gastrodia elata in a steamer, the depth of the water in the pot is 6cm. During the steaming process, the firepower is kept stable to keep the water in the pot boiling all the time, and the steaming time is 8 minutes. After the steaming is completed, the black Gastrodia elata is quickly taken out and put into a sterile cooling room at a temperature of 10-15°C.

[0014] Preferably, in S4, before the freezing tray is put into the freezer, it needs to be pre-cooled in an environment of -12°C for 12 minutes. When the black Gastrodia elata is placed on the freezing tray, the distance between each other is 1.5cm.

[0015] Preferably, in S5, the negative pressure of the freeze dryer is controlled at 0.02MPa. During the drying process, the black Gastrodia elata in the freeze dryer is turned over once every 7 hours. The drying time is 42 hours, and the drying temperature is 35°C.

[0016] Preferably, during the preparation process, the tools and equipment in contact with the black Gastrodia elata need to be sterilized by high-temperature steam treatment, with a sterilization temperature of 121°C and a sterilization time of 25 minutes.

[0017] Compared with the prior art, the present invention has the following beneficial effects:

[0018] 1. Through strict screening of raw materials, only the zero-generation or first-generation fruits of black Gastrodia elata are selected and their sizes are controlled, laying a good foundation for the product quality; in the cleaning and grading process, not only impurities are effectively removed, but also ozone sterilization and sterile cold air drying are used to reduce microorganisms and prevent moisture residue. In the subsequent steaming, quick-freezing and vacuum drying processes, parameters such as time, temperature, and pressure are precisely controlled, not only protecting the cell structure of the black Gastrodia elata and retaining a large amount of nutrients, but also maintaining its original flavor to the greatest extent. From the overall processing flow, each step is closely coordinated and acts together to achieve efficient freshness preservation, enabling consumers to taste products close to fresh black Gastrodia elata and meeting the demand for high-quality black Gastrodia elata products.

[0019] 2. The present invention has achieved remarkable results in improving product quality and extending the shelf life. During the entire preparation process, tools and equipment in contact with Gastrodia elata Bl. f. glauca S. Chow are strictly disinfected with high-temperature steam, reducing the possibility of microbial contamination and ensuring product safety. During processing, standardization of cleaning and grading, precision of ozone treatment, refinement of drying conditions, etc. ensure the stability of product quality, improve product quality, extend the shelf life of the product, make the product more competitive in the market, and create favorable conditions for the industrial production and wide market promotion of Gastrodia elata Bl. f. glauca S. Chow. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 is a schematic diagram of the overall process of the present invention; DETAILED DESCRIPTION OF THE EMBODIMENTS

[0021] In order to make the technical means, creative features, achieved objectives and effects of the present invention easy to understand, the present invention will be further described below in conjunction with specific embodiments.

[0022] Example 1

[0023] As Figure 1 shown, a processing method for freeze-dried and freshness-locked Gastrodia elata Bl. f. glauca S. Chow includes the following steps:

[0024] S1: Raw material selection, select zero-generation or first-generation fruits of Gastrodia elata Bl. f. glauca S. Chow, ensuring that the fruit length is within 5 cm and the fruit diameter is within 3 cm;

[0025] S2: Cleaning and grading, clean the selected Gastrodia elata Bl. f. glauca S. Chow to remove surface impurities, and perform grading treatment according to size, shape, etc.;

[0026] S3: Steaming treatment, put the cleaned and graded Gastrodia elata Bl. f. glauca S. Chow into a steamer, and steam for 5 - 10 minutes after the water boils until cooked;

[0027] S4: Quick-freezing and forming, place the cooked Gastrodia elata Bl. f. glauca S. Chow on a freezing tray, and then put it into a freezer at a temperature of -30 - -40 °C for quick-freezing to make it form;

[0028] S5: Vacuum drying, put the quick-frozen and formed Gastrodia elata Bl. f. glauca S. Chow into a freeze dryer, and perform vacuum drying for 36 - 48 hours in a negative pressure environment. The temperature is controlled at 30 - 40 °C during the drying process.

[0029] Specifically, in S2, when cleaning Gastrodia elata Bl. f. glauca S. Chow, first rinse it with flowing water for 3 minutes to initially remove visible surface impurities. Subsequently, soak Gastrodia elata Bl. f. glauca S. Chow in a mixed aqueous solution containing 0.3% (w / v) food-grade citric acid and 0.2% (w / v) food-grade baking soda for 5 minutes, and use an acid-base reaction to further remove residual pesticides and dirt that are difficult to clean. Then rinse it with flowing water for 2 minutes to ensure thorough cleaning;

[0030] Among them, for the acid-base neutralization problem, when the reaction between the two is incomplete and an acidic environment remains:

[0031] Concentration calculation: The molar concentrations of citric acid (0.3% w / v) and baking soda (0.2% w / v) are approximately 0.0156 mol / L and 0.0238 mol / L respectively. Since citric acid is a tribasic acid (able to release 3 H + ), the total H + concentration it provides is 0.0468 mol / L, while baking soda can only neutralize 0.0238 mol / L of it. Finally, there is still 0.023 mol / L of H + remaining in the solution. Therefore, the mixture is still weakly acidic (pH≈2.5 - 3.5), retaining the chelating ability of citric acid, which helps to remove metal ions and some pesticides;

[0032] The carbon dioxide gas (CO 2 ) generated by the reaction will also produce a large number of tiny bubbles. When these bubbles burst on the surface of Gastrodia elata Bl. f. glauca S. Chow, they can carry away the dirt and pesticide residues that are difficult to clean through physical scouring; The generated sodium citrate is a surfactant, which can reduce the surface tension of water, enhance wettability and detergency, and further improve the cleaning efficiency;

[0033] The weak acidity of citric acid can decompose alkaline pesticides (such as organophosphorus) and adsorb heavy metals through chelation;

[0034] The weak alkalinity of baking soda (pH≈8 - 9) helps to decompose acidic pesticides (such as pyrethroids) and oil-based dirt. Although partially neutralized, a short soak (5 minutes) is sufficient to utilize the initial properties of both;

[0035] Therefore, although citric acid and baking soda will undergo a partial neutralization reaction, by precisely controlling the concentration ratio and soaking time, it combines chemical decomposition (acid / alkali environment), physical scouring (CO 2 bubbles) and surfactant action (sodium citrate), and finally achieves the effect of high-efficiency decontamination and pesticide residue removal.

[0036] During grading, use a high-precision electronic balance to weigh Gastrodia elata Bl. f. glauca S. Chow, and accurately divide it into three grades: light, medium, and heavy according to the weight difference. The weight range of the light grade is 10 - 20 g, the weight range of the medium grade is 26 - 30 g, and the weight range of the heavy grade is 34 - 38 g. For the graded Gastrodia elata Bl. f. glauca S. Chow, place them in disinfected food-grade plastic trays according to different grades to avoid cross-contamination.

[0037] Furthermore, after S2, place the Gastrodia elata Bl. f. glauca S. Chow of different grades in an ozone concentration of 5 mg / m 3Perform a 10-minute sterilization treatment in an environment to further reduce the microbial count. After the treatment, quickly dry the surface moisture of the Gastrodia elata Bl. f. glauca S. Chow with sterile cold air, with the wind speed controlled at 3 m / s and the time being 5 minutes to prevent water residue from affecting subsequent processing.

[0038] Furthermore, in S3, the steamer is a stainless-steel steamer with an intelligent temperature control function, and the depth of the water in the pot is 6 cm.

[0039] Before steaming, preheat the steamer to the state of rapid boiling of water, and then put the steamer tray with Gastrodia elata Bl. f. glauca S. Chow into the pot. During the steaming process, keep the firepower stable through the intelligent temperature control system, so that the pot is always in a state of violent boiling, and the steaming time is accurately controlled for 8 minutes. After the steaming is over, quickly take out the Gastrodia elata Bl. f. glauca S. Chow and send it into a sterile cooling room at a temperature of 10 - 15 °C by using an automatic transmission device. This cooling room is equipped with an air purification system that can filter microorganisms and impurities in the air, and can reduce the surface temperature of Gastrodia elata Bl. f. glauca S. Chow below 30 °C within 1 - 2 minutes to prevent the quality of Gastrodia elata Bl. f. glauca S. Chow from deteriorating due to residual heat.

[0040] Furthermore, in S4, the freezing tray is made of 304 stainless steel with a Teflon non-stick coating on the surface. Before putting it into the freezer, it needs to be pre-cooled in an environment of -12 °C for 12 minutes. When placing the Gastrodia elata Bl. f. glauca S. Chow on the freezing tray, use a customized spacer mold to ensure a 1.5 cm interval between each other, so as to ensure that cold air can circulate evenly during the freezing process and achieve rapid and uniform freezing.

[0041] The freezer uses a two-stage compression refrigeration system, which has the characteristics of high temperature control accuracy and fast cooling rate. During the quick-freezing process, first reduce the temperature to -20 °C within 30 minutes at a relatively fast cooling rate, and then slowly reduce it to -35 °C at a rate of 1 - 2 °C / min, and maintain it at this temperature for 2 hours to form small and uniform ice crystals inside the Gastrodia elata Bl. f. glauca S. Chow, reduce the damage to the cell structure, and retain the nutritional components and original taste of the Gastrodia elata Bl. f. glauca S. Chow to the greatest extent.

[0042] The above-mentioned customized mold is made of food-grade polypropylene (PP) or silicone material, and has the characteristics of being resistant to low temperature (no deformation below -40 °C), non-toxic and odorless, and easy to clean. Its shape is a flat plate structure, and circular or oval pits with a diameter slightly larger than the fruit diameter of Gastrodia elata Bl. f. glauca S. Chow (about 3.5 cm) are evenly distributed on the surface. The center distance of the pits is strictly set to 1.5 cm, and the mold size is exactly matched with the freezing tray to ensure that it fits tightly with the tray body after being put in and avoid displacement.

[0043] The placement position of Gastrodia elata Bl. f. glauca S. Chow can be restricted by the pits on the mold to ensure that the spacing between each fruit is strictly controlled at 1.5 cm, avoiding adhesion caused by contact during the freezing process. The bottom of the pit is designed with ventilation holes (with a diameter of 1 - 2 mm) to allow cold air to penetrate the bottom of the mold and directly contact the bottom surface of Gastrodia elata Bl. f. glauca S. Chow, improving the freezing uniformity. The surface of the mold is treated with a nano-level Teflon coating to further reduce the adhesion force between Gastrodia elata Bl. f. glauca S. Chow and the mold, facilitating demolding after freezing.

[0044] Further, in S5, before loading Gastrodia elata Bl. f. glauca S. Chow into the freeze dryer, the internal cavity is first disinfected with ultraviolet light for 30 minutes, and at the same time, the ozone generator is turned on for 15 minutes of ozone disinfection to ensure a sterile internal environment. After disinfection, the internal gas of the freeze dryer is pumped to a negative pressure of 0.02 MPa using a vacuum pump.

[0045] During the drying process, the Gastrodia elata Bl. f. glauca S. Chow in the freeze dryer is gently flipped once every 7 hours by an automated robotic arm to make the drying degree of each part more uniform. The drying time is 42 hours, and the drying temperature is stably controlled at 35°C. In addition, high-purity nitrogen that has been dried and filtered is charged into the freeze dryer once every 12 hours, and each charging time is 5 minutes. The charging volume briefly raises the pressure in the freeze dryer to 0.03 MPa to promote the sublimation of moisture and improve the drying efficiency and quality. After drying, dry nitrogen is charged into the freeze dryer until it reaches atmospheric pressure, and then the Gastrodia elata Bl. f. glauca S. Chow is taken out through the automatic discharging system.

[0046] Further, during the preparation process, tools and equipment that come into contact with Gastrodia elata Bl. f. glauca S. Chow, including but not limited to knives, tweezers, conveyor belts, freezing trays, etc., all need to be disinfected by high-temperature steam. The disinfection temperature is 121°C, and the disinfection time is 25 minutes. For large equipment such as steamers and freeze dryers, in addition to the above-mentioned disinfection operations on the internal cavity, the external surface of the equipment and parts such as pipes in contact with the materials also need to be regularly wiped and disinfected with 75% (v / v) medical alcohol.

[0047] Example 2. In this example, the processing method is adjusted based on Example 1, as follows:

[0048] Raw material selection: The same as in Example 1;

[0049] Cleaning and grading: Rinse with flowing clean water for 4 minutes, the grading weight range is the same as in Example 1, ozone concentration 6 mg / m 3 Sterilization for 12 minutes, blow with sterile cold air at 3.5 m / s for 6 minutes;

[0050] Steaming treatment: The water in the steamer is 7 cm deep, steam for 9 minutes, and the temperature in the cooling chamber is 11 - 16°C;

[0051] Quick freezing and forming: Pre-cool the freezing tray at -13°C for 13 minutes, the spacing of Gastrodia elata Bl. f. glauca S. Chow is 1.6 cm, and quick-freeze at -31 - -41°C;

[0052] Vacuum drying: The negative pressure of the freeze dryer is 0.025 MPa, drying at 36°C for 43 hours, turning over every 7.5 hours;

[0053] Disinfection of tools and equipment: The same as in Example 1.

[0054] Example 3, in this example, the processing method is adjusted on the basis of Example 1, specifically as follows:

[0055] Raw material selection: The same as in Example 1;

[0056] Cleaning and grading: Flushing with flowing clean water for 3.5 minutes, the grading weight range is the same as in Example 1, ozone concentration 4 mg / m 3 Sterilization for 8 minutes, blowing with sterile cold air at 2.5 m / s for 4 minutes;

[0057] Steaming treatment: The water in the steamer is 5.5 cm deep, steaming for 7 minutes, the temperature in the cooling chamber is 9 - 14°C;

[0058] Quick freezing and forming: Pre-cooling the freezing tray at -11°C for 11 minutes, the interval between Gastrodia elata is 1.4 cm, quick freezing at -29 - -39°C;

[0059] Vacuum drying: The negative pressure of the freeze dryer is 0.015 MPa, drying at 34°C for 41 hours, turning over every 6.5 hours;

[0060] Disinfection of tools and equipment: The same as in Example 1.

[0061] Example 4, in this example, the processing method is adjusted on the basis of Example 1, specifically as follows:

[0062] Raw material selection: The same as in Example 1;

[0063] Cleaning and grading: Flushing with flowing clean water for 5 minutes, the grading weight range is the same as in Example 1, ozone concentration 7 mg / m 3 Sterilization for 15 minutes, blowing with sterile cold air at 4 m / s for 7 minutes;

[0064] Steaming treatment: The water in the steamer is 8 cm deep, steaming for 10 minutes, the temperature in the cooling chamber is 12 - 17°C;

[0065] Quick freezing and forming: Pre-cooling the freezing tray at -14°C for 14 minutes, the interval between Gastrodia elata is 1.7 cm, quick freezing at -32 - -42°C;

[0066] Vacuum drying: The negative pressure of the freeze dryer is 0.03 MPa, drying at 37°C for 44 hours, turning over every 8 hours;

[0067] Disinfection of tools and equipment: The same as in Example 1.

[0068] Comparative Example 1, in this comparative example, the processing method is adjusted on the basis of Example 1, specifically as follows:

[0069] Raw material selection: Select the zero-generation or first-generation fruits of Gastrodia elata Blume f. glauca S. Chow, but the fruit length and fruit diameter are not strictly controlled;

[0070] Cleaning and grading: Simply rinse with clean water for 1 minute without grading; there is no ozone sterilization and cold air drying steps;

[0071] Steaming treatment: The water in the steamer can be arbitrary, steam for 15 minutes, and then cool naturally after steaming;

[0072] Quick freezing and forming: The freezing tray is not pre-cooled, and the Gastrodia elata Blume f. glauca S. Chow is placed randomly, and quick-frozen at -20--25°C;

[0073] Vacuum drying: The negative pressure of the freeze dryer is unstable, about 0.05 MPa, dried at 45°C for 30 hours without turning;

[0074] Tool and equipment disinfection: High-temperature steam disinfection is not carried out.

[0075] Comparative example 2, in this comparative example, the processing method is adjusted on the basis of Example 1, as follows:

[0076] Raw material selection: Select the second-generation fruits of Gastrodia elata Blume f. glauca S. Chow, and the fruit length and fruit diameter are not controlled.

[0077] Cleaning and grading: Rinse with flowing clean water for 2 minutes, simply divide into two grades according to size, ozone concentration 2mg / m 3 Sterilize for 5 minutes, and blow with sterile cold air at 1m / s for 3 minutes;

[0078] Steaming treatment: The water in the steamer is 4 cm deep, steam for 4 minutes, and the temperature in the cooling chamber is 20-25°C;

[0079] Quick freezing and forming: The freezing tray is pre-cooled at -5°C for 5 minutes, the Gastrodia elata Blume f. glauca S. Chow is spaced 0.5 cm apart, and quick-frozen at -25--30°C;

[0080] Vacuum drying: The negative pressure of the freeze dryer is 0.01 MPa, dried at 30°C for 50 hours, and turned over every 10 hours;

[0081] Tool and equipment disinfection: Sterilize with 100°C steam for 15 minutes.

[0082] According to the processing methods of the above Examples 1-4 and Comparative Examples 1-2, compare the effects of different freeze-drying and freshness-locking processing methods of Gastrodia elata Blume f. glauca S. Chow on product quality, including moisture content, rehydration performance, taste, and appearance preservation, so as to determine the best processing technology and record the test results in detail.

[0083] Detection index: Moisture content: Using the drying method, take a certain amount of freeze-dried Gastrodia elata Blume f. glauca S. Chow, dry it to constant weight in an oven at 105°C, and calculate the moisture content.

[0084] Rehydration performance: Put the freeze-dried Gastrodia elata Blume f. glauca S. Chow into a certain amount of normal-temperature water, and record the time required for complete rehydration.

[0085] Taste: A 10-member professional tasting panel was organized to rate the food based on texture, flavor, etc., with a maximum score of 10.

[0086] Appearance preservation condition: Observe the color and shape changes of the product after 1 month of storage and record them according to the severity.

[0087] See the table below for details:

[0088]

[0089]

[0090] This experiment conducted multi-faceted quality tests on freeze-dried fresh-locking black gastrodia elata processed by 6 different processing methods. After comparative analysis, it was found that Example 3 performed best in various indicators and was most suitable as a processing technology for freeze-dried fresh-locking black gastrodia elata. In comparison, Comparative Examples 1 and 2 had obvious deficiencies in various indicators. Comparative Example 1 has a high moisture content, slow rehydration, poor taste, and large changes in appearance, mainly due to its lax selection of raw materials, lack of precise control of the processing process, and failure to carry out necessary disinfection treatment; although some indicators of Comparative Example 2 are slightly better than those of Comparative Example 1, the overall performance is still inferior to that of each embodiment, and its raw material selection and some unreasonable processing parameters affect the product quality. Although Examples 1, 2, and 4 perform well in some indicators, comprehensive comparison shows that Example 3 has obvious comprehensive advantages in terms of moisture content, rehydration performance, taste, and appearance preservation, and is the most ideal freeze-dried fresh-locking black gastrodia elata processing technology.

[0091] The above shows and describes the basic principles and main features of the present invention and the advantages of the present invention. It should be understood by those skilled in the art that the present invention is not limited to the above embodiments. The above embodiments and descriptions are only for explaining the principles of the present invention. Without departing from the spirit and scope of the present invention, the present invention may have various changes and improvements, which fall within the scope of the present invention to be protected. The scope of protection of the present invention is defined by the attached claims and their equivalents.

Claims

1. A freeze-dried fresh-keeping method for processing black gastrodia elata, characterized in that: The following steps are involved: S1: Raw material selection, selecting black gastrodia elata raw material, wherein the black gastrodia elata raw material is one of zero-generation fruit and first-generation fruit; S2: Cleaning and grading: cleaning the selected black gastrodia elata, removing surface impurities, and grading them according to size, shape, etc.; S3: steaming, putting the washed and graded black gastrodia elata into a steamer, and steaming for 5 to 10 minutes after the water is boiled, until steamed; S4: quick freezing and forming, placing the steamed black gastrodia elata on a freezing plate, and then putting it into a freezer at a temperature of -30-40 degrees for quick freezing to form it; S5: Vacuum drying: put the quick-frozen black gastrodia into the freeze dryer and perform vacuum drying for 36-48 hours under negative pressure. The temperature is controlled at 30-40 degrees during the drying process.

2. A freeze-dried fresh-keeping black gastrodia processing method according to claim 1, characterized in that: In S2, the black gastrodia elata is washed with running water for 3 minutes, and is classified into three grades of light, medium and heavy according to the weight difference of the black gastrodia elata, wherein the weight range of the light grade is 10-20g, the weight range of the medium grade is 26-30g, and the weight range of the heavy grade is 34-38g.

3. A freeze-dried fresh-keeping black gastrodia processing method according to claim 1, characterized in that: After the S2 is cleaned and classified, different grades of Gastrodia elata are placed in an ozone concentration of 5 mg / m 3 The sterilization treatment was carried out in an environment for 10 minutes. After the treatment, sterile cold air was used to quickly dry the surface moisture of Gastrodia elata at a wind speed of 3m / s for 5 minutes.

4. A freeze-dried fresh-keeping black gastrodia processing method according to claim 1, characterized in that: In S3, when the steamer is steaming the black gastrodia elata, the depth of water in the pot is 6 cm, and the fire is kept stable during the steaming process so that the pot is always in a boiling state. The steaming time is 8 minutes. After the steaming is completed, the black gastrodia elata is quickly taken out and placed in a sterile cooling chamber with a temperature of 10-15°C.

5. A freeze-dried fresh-keeping black gastrodia processing method according to claim 1, characterized in that: In S4, the freezing plate needs to be pre-cooled at -12°C for 12 minutes before being placed in the freezer, and the black gastrodia elata are placed on the freezing plate with a spacing of 1.5 cm between them.

6. A freeze-dried fresh-keeping black gastrodia processing method according to claim 1, characterized in that: In S5, the negative pressure of the freeze dryer is controlled at 0.02 MPa. During the drying process, the black gastrodia elata in the freeze dryer is turned over every 7 hours. The drying time is 42 hours and the drying temperature is 35°C.

7. A freeze-dried fresh-keeping method for processing black gastrodia elata according to claim 1, characterized in that: All tools and equipment that come into contact with Gastrodia elata must be sterilized with high-temperature steam at a temperature of 121°C for 25 minutes.

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