Method for preparing tricholoma matsutake powder through low-temperature drying

Abstract

The invention relates to the technical field of food processing or health care products, and particularly discloses a method for preparing tricholoma matsutake powder through low-temperature drying. The tricholoma matsutake powder is mainly prepared from artificially planted fresh tricholoma matsutake. The preparation method comprises the following steps: firstly, carrying out raw material pretreatment of cold-chain transportation, cleaning and low-temperature pulping on the fresh tricholoma matsutake; homogenizing the tricholoma matsutake slurry, and introducing inert gas to pretreat the tricholoma matsutake slurry; then low-temperature drying with staged program temperature control is carried out; grinding and screening in a low-temperature environment; performing sterilization treatment of non-thermal high-pressure sterilization and physical adsorption dehumidification in sequence; and finally, sterile filling is completed in a nitrogen filling environment. The tricholoma matsutake powder can be used for food processing or health care product production, and has the advantages that core functional components are fully reserved, and the tricholoma matsutake powder is difficult to oxidize and deteriorate during storage; besides, according to the preparation method disclosed by the invention, through whole-process low-temperature and low-oxygen cooperative control, nutritional ingredients are prevented from being damaged by high temperature, moisture and microbiological indexes can be effectively regulated and controlled, and both quality and safety are considered.

Description

Technical Field

[0001] This application relates to the field of food processing or health product technology, and more specifically, it relates to a method for preparing matsutake mushroom powder by low-temperature drying. Background Technology

[0002] Matsutake mushrooms, a rare food rich in various active ingredients such as matsutake alcohol and matsutake polysaccharides, have high application value in the food and health product fields due to their ease of storage, transportation, and consumption. To meet market demand for matsutake powder, current technologies primarily employ drying to process fresh matsutake mushrooms into powder. Drying is a crucial step in matsutake powder preparation, directly affecting its quality, especially the retention of its core active ingredients. The content of these core active ingredients determines the nutritional and application value of the matsutake powder. Therefore, how to better preserve these components during drying and subsequent processing has become a key focus in the matsutake powder preparation field.

[0003] However, in existing matsutake powder preparation processes, the drying stage often employs traditional hot air drying or freeze drying alone. Traditional hot air drying requires high temperatures, which can easily lead to the thermal degradation of heat-sensitive active ingredients such as matsutake alcohol and matsutake polysaccharides. At the same time, existing processes lack effective low-oxygen protection measures in the handling of fresh matsutake raw materials, storage of the pulp, and packaging of finished products. This makes the active ingredients in matsutake easily come into contact with oxygen and undergo oxidation reactions, further causing the loss of core functional components. Ultimately, this results in a low retention rate of core functional components in the prepared matsutake powder, making it difficult to meet the market demand for high-quality matsutake powder. Summary of the Invention

[0004] To address the problem of low retention rate of the core active ingredients of matsutake mushrooms due to high-temperature oxidation during processing in existing technologies, this application provides a method for preparing matsutake mushroom powder by low-temperature drying.

[0005] A method for preparing matsutake mushroom powder by low-temperature drying includes the following steps:

[0006] S1. Raw material pretreatment: Fresh matsutake mushrooms transported via cold chain are washed with purified water, and then the washed fresh matsutake mushrooms are pulped under low temperature conditions to obtain matsutake mushroom pulp.

[0007] S2. Pulp pretreatment: The matsutake slurry is homogenized while inert gas is continuously introduced onto the surface of the slurry.

[0008] S3. Low-temperature drying: The matsutake mushroom pulp after S2 treatment is subjected to staged temperature-controlled drying to obtain matsutake mushroom powder.

[0009] S4. Grinding and sieving: Grind the dried matsutake powder at a low temperature of 10-15℃, and then sieve the ground matsutake powder using a 200-250 mesh vibrating screen.

[0010] S5. Sterilization treatment: The sieved matsutake powder is subjected to non-thermal high-pressure sterilization and physical adsorption dehumidification treatment in sequence.

[0011] S6. Aseptic filling: The sterilized matsutake powder is filled and boxed in a nitrogen-filled environment, where the relative humidity of the filling environment is controlled below 25%.

[0012] By adopting the above technical solutions, cold chain transportation of fresh matsutake mushrooms maintains the freshness of the raw materials; washing with purified water removes impurities from the surface of the raw materials; low-temperature pulping reduces the impact of temperature on the raw material composition during processing, thus providing a stable foundation for subsequent processing; homogenization of the matsutake pulp refines the particles and makes the pulp components more evenly distributed; continuous introduction of inert gas isolates the pulp from air, preventing contact with oxygen, thus providing a uniform and non-oxidizing pulp raw material for subsequent drying; and staged temperature-controlled drying gradually removes moisture from the pulp, avoiding the problems associated with a single drying process. The process of grinding at low temperatures reduces the impact of temperature rise on the composition, while using a vibrating sieve with a specific mesh size controls the particle size, resulting in a powder with uniform particle size. Non-thermal high-pressure sterilization kills microorganisms in the powder, and food-grade silica gel is used for physical adsorption and dehumidification to remove residual moisture, thus achieving hygienic and dry control of the powder. Nitrogen-filled packaging isolates oxygen, and controlling the relative humidity of the filling environment prevents external moisture from entering the packaging, thus providing a stable environment for finished product storage.

[0013] Preferably, in step S1, the fresh matsutake mushrooms are artificially cultivated matsutake mushrooms with a matsutake alcohol content of 0.2-0.5 ml / kg and a growth period of 6-9 days; the washing process uses a multi-stage spraying system with a water pressure of 0.2-0.5 MPa.

[0014] By adopting the above technical solution, and by selecting artificially cultivated fresh matsutake mushrooms with matsutake alcohol content and growth period within a specific range, the basic quality of raw materials and the initial content of core components are guaranteed. By using multi-stage spraying equipment and controlling specific water pressure for cleaning, impurities can be effectively removed while reducing damage to raw materials, thereby providing high-quality raw materials for subsequent processing.

[0015] Preferably, in step S1, the pulping is carried out in a high-speed low-temperature pulper, with a pulping temperature of 0-10℃, a pulping speed of 5000-8000 rpm, a pulping time of 5-10 min, and a pulping particle size of 80-120 mesh.

[0016] By adopting the above technical solution, pulping is performed in a high-speed, low-temperature pulping machine, and the pulping temperature is controlled at 0-10℃. This helps to prevent changes in heat-sensitive components in the raw materials caused by temperature rise during pulping. At the same time, setting a pulping speed of 5000-8000 rpm and a pulping time of 5-10 minutes, and controlling the pulping particle size at 80-120 mesh, can effectively refine the particles of fresh matsutake mushroom raw materials, making the pulp texture more uniform. This provides matsutake mushroom pulp with suitable particle size and stable composition for subsequent pulp pretreatment and drying, reducing quality differences caused by uneven pulp particles during subsequent processing.

[0017] Preferably, in step S1, the transport temperature of the cold chain transportation is controlled at 0-4℃, and the transport time does not exceed 12 hours.

[0018] By controlling the temperature of cold chain transportation within 0-4℃, the reproduction rate of microorganisms in fresh matsutake mushrooms can be effectively inhibited. At the same time, the activity of enzymes such as polyphenol oxidase and peroxidase can be reduced, thereby reducing the decomposition of core active ingredients such as matsutake alcohol by enzymatic reactions. This helps maintain the freshness of the raw materials and the initial content of core components. At the same time, limiting the transportation time to no more than 12 hours can avoid the slow quality deterioration that may still occur in fresh matsutake mushrooms under low temperature conditions during long-term transportation, such as slight loss of moisture and slight volatilization of flavor substances. This ensures that when fresh matsutake mushrooms arrive at the processing stage, their appearance, taste, and internal components are all in good condition. This provides stable raw materials for subsequent pre-processing steps such as washing and pulping, and reduces the impact of early quality loss of raw materials on the quality of the final matsutake powder product.

[0019] Preferably, in step S2, the homogenization treatment pressure is 20-35 MPa, and the number of cycles is 2-4; the inert gas is food-grade nitrogen or argon, and the gas flow rate is 5-15 L / min.

[0020] By adopting the above technical solution, and controlling the homogenization treatment pressure at 20-35 MPa and circulating it 2-4 times, the fiber particles in the matsutake mushroom pulp are fully broken down, and the distribution of nutrients and moisture inside the pulp is made more uniform. This avoids uneven concentration of components in some areas of the pulp and ensures that moisture is removed from each area simultaneously during the subsequent staged drying. By using food-grade nitrogen or argon as inert gas, these gases are chemically stable and meet food safety requirements. They can effectively isolate air, and the gas flow rate is controlled at 5-15 L / min. This continuously forms a stable protective gas layer on the surface of the pulp, preventing the pulp from contacting oxygen. This reduces the loss of heat-sensitive components such as matsutake alcohol in the pulp due to oxidation and maintains the quality stability of the pulp.

[0021] Preferably, in step S3, the staged programmed temperature-controlled drying specifically includes:

[0022] First stage: Dry at 30-35℃ for 60-90 minutes;

[0023] Second stage: Raise the temperature to 36-40℃ and continue drying for 90-120 minutes;

[0024] The third stage: raise the temperature to 41-50℃ and dry until the moisture content of the slurry is less than 5wt%.

[0025] By employing the above technical solution, the first stage involves drying at 30-35℃ for 60-90 minutes. This temperature range is gentle and the drying time is sufficient, slowly removing free water from the surface of the matsutake mushroom paste. This prevents the formation of a hard shell on the surface due to rapid dehydration at high temperatures, which would hinder the subsequent removal of internal moisture. The second stage raises the temperature to 36-40℃ and continues drying for 90-120 minutes. This increased temperature enhances the moisture removal process, penetrating deeper into the paste to effectively remove bound water and ensure uniform moisture removal from all areas. The third stage further raises the temperature to 41-50℃ and dries until the moisture content is below 5wt%. The slightly higher temperature improves the final dehydration efficiency, ensuring the matsutake powder meets moisture standards and reducing the risk of microbial growth during subsequent storage. Overall, by controlling the temperature and drying time in stages, the system avoids the problems of incomplete drying or excessive loss of heat-sensitive components that may occur under single drying conditions, ensuring the drying quality and component stability of the matsutake powder.

[0026] Preferably, after the second stage of drying is completed, the pressure control program is activated to reduce the pressure in the drying chamber from atmospheric pressure to -0.02 MPa to -0.05 MPa within 5 minutes, and the third stage of drying is carried out under this pressure condition.

[0027] By adopting the above technical solution, after the second stage of drying is completed, the pressure control program is activated, and the pressure in the drying chamber is reduced from atmospheric pressure to -0.02MPa to -0.05MPa within 5 minutes. This pressure reduction process is stable and the speed is controllable, which can avoid damage to the surface structure of the matsutake mushroom slurry or agglomeration of powder particles due to sudden pressure changes. At the same time, the negative pressure environment can lower the boiling point of water, so that the water in the slurry can still be efficiently vaporized and removed at a relatively low temperature during the third stage of drying. The subsequent third stage of drying under this negative pressure condition can not only rely on the negative pressure to continuously enhance the water removal power and ensure that the slurry is dried quickly to a moisture content of less than 5wt%, but also reduce the thermal degradation of heat-sensitive components such as matsutake alcohol that may be caused by the slightly higher temperature in the third stage. Thus, while ensuring drying efficiency, the stability and quality of the core components of matsutake powder are better maintained.

[0028] Preferably, in step S5, the working pressure of the non-thermal high-pressure sterilization is 300-600 MPa, the holding time is 3-5 min, and the processing temperature is 15-25℃.

[0029] By adopting the above technical solution, and setting a non-thermal high-pressure sterilization temperature of 15-25℃, which is within the normal temperature range, the thermal degradation of heat-sensitive active ingredients such as matsutake alcohol and matsutake polysaccharides in matsutake powder by high-temperature environments can be avoided, thus protecting the core components from temperature damage. At the same time, controlling the working pressure to 300-600MPa can physically compress and destroy the cell walls and cell membranes of microorganisms in the powder, rendering them inactive. Combined with a pressure holding time of 3-5 minutes, this ensures that the pressure fully penetrates into the powder, covering all areas where microorganisms may exist, and thoroughly killing bacteria, molds, and other microorganisms. Thus, while ensuring that matsutake powder meets hygiene and safety standards and satisfies the requirements for consumption and storage, the integrity of its core active ingredients is maintained to the greatest extent, avoiding the component loss problem caused by high temperatures in traditional thermal sterilization, and providing a guarantee for the stable quality of the subsequent finished product.

[0030] Preferably, in step S5, the physical adsorption dehumidification treatment involves treating the matsutake powder with food-grade silica gel. The amount of silica gel used is 5-10% of the mass of the matsutake powder, and the treatment time is 10-30 seconds.

[0031] By adopting the above technical solution, food-grade silica gel is used to physically adsorb and dehumidify matsutake mushroom powder. Food-grade silica gel meets food safety requirements and will not contaminate the powder. It also has stable adsorption properties, specifically targeting residual moisture in the powder. The silica gel dosage is controlled at 5-10% of the matsutake mushroom powder's mass. This dosage ensures sufficient adsorption capacity, allowing the silica gel to fully contact the powder and adsorb trace amounts of moisture, preventing moisture residue due to insufficient adsorbent. A processing time of 10-30 seconds ensures sufficient contact time between the silica gel and powder for moisture adsorption, while preventing secondary moisture absorption or impact on subsequent processing efficiency due to prolonged exposure to air. This allows for precise control of the matsutake mushroom powder's moisture content, maintaining its dry state and reducing problems such as clumping and microbial growth caused by excessive moisture during storage, thus ensuring stable product quality.

[0032] Preferably, in step S6, the nitrogen-filled environment is formed by filling the packaging container with nitrogen gas and controlling the oxygen volume concentration in the container to be below 3%.

[0033] By adopting the above technical solution, nitrogen gas is introduced into the packaging container. As a chemically stable inert gas, nitrogen can effectively replace the air originally contained in the container, thus isolating external oxygen from entering the container and preventing direct contact between the matsutake powder and oxygen. At the same time, the oxygen volume concentration in the container is controlled to be below 3%. This low-oxygen environment can further inhibit the loss of heat-sensitive active ingredients such as matsutake alcohol in the matsutake powder due to oxidation reactions, and also reduce the slow reproduction of microorganisms that may be caused by residual oxygen in the container. In this way, the quality stability of the matsutake powder is maintained during storage, avoiding problems such as flavor deterioration, loss of nutrients, or exceeding hygiene standards, thus providing a guarantee for the long-term storage of the finished matsutake powder.

[0034] In summary, this application has the following beneficial effects:

[0035] 1. Because this application adopts a whole-process low-temperature processing system that includes slurry inert gas protection, staged temperature-controlled drying and final nitrogen-filled packaging, the system systematically constructs a low-oxygen and low-temperature environment from processing to finished product, which minimizes the oxidation and thermal degradation of heat-sensitive active ingredients, thus achieving the beneficial effect of significantly improving the retention rate of core functional ingredients such as matsutake alcohol and matsutake polysaccharide.

[0036] 2. In this application, a staged temperature-controlled drying process combined with a pressure-gradient synergistic process is preferred. Because this process first lowers the temperature and then slowly raises it while introducing negative pressure, it achieves efficient removal of moisture at low temperatures without damaging the active ingredients of the material. Therefore, it achieves the beneficial effect of significantly shortening the drying cycle and reducing overall energy consumption while ensuring high-quality products.

[0037] 3. The method of this application combines non-thermal high-pressure sterilization and physical adsorption dehumidification in the post-treatment of matsutake powder. Since non-thermal sterilization avoids secondary heat damage and physical dehumidification actively reduces the water activity of the product, it achieves the beneficial effect of significantly improving the storage stability of the product and preventing moisture absorption and clumping while effectively controlling microbial indicators. Attached Figure Description

[0038] Figure 1 This is a flowchart of a method for preparing matsutake powder by low-temperature drying, as provided in this application. Detailed Implementation

[0039] The present application will be further described in detail below with reference to embodiments and comparative examples. Unless otherwise specified, the experimental methods used below are conventional methods. Unless otherwise specified, the materials, reagents, methods and instruments used are all conventional materials, reagents, methods and instruments in the art, which can be obtained by those skilled in the art through commercial channels or prepared according to literature methods.

[0040] Technical concept:

[0041] Traditional matsutake mushroom powder preparation techniques suffer from low retention rates of active ingredients and insufficient storage stability. This is because traditional drying methods often employ either high-temperature hot air drying or simple freeze-drying. High temperatures easily lead to the thermal degradation of heat-sensitive components such as matsutake alcohol and matsutake polysaccharides, while freeze-drying alone lacks adequate oxygen protection throughout the processing. Furthermore, the lack of air isolation during the slurry treatment stage easily triggers oxidation reactions, sterilization relies heavily on heat sterilization, further damaging nutrients, and the dehumidification process often suffers from excessive residual moisture in the powder due to limited methods. All these factors contribute to a decline in the quality of the finished product.

[0042] This technical solution addresses this issue by constructing a collaborative technical system across the entire process: At the raw material end, cold chain transportation at 0-4℃ and low-temperature pulping at 0-10℃ are employed to prevent initial component deterioration; during pulp pretreatment, food-grade nitrogen or argon is introduced to create a low-oxygen environment, coupled with homogenization at 20-35MPa to ensure pulp uniformity; in the drying stage, phased temperature control is employed, with pressure reduced to -0.02MPa to -0.05MPa before the third stage to balance drying efficiency and component protection; subsequently, non-thermal high-pressure sterilization at 300-600MPa avoids high-temperature damage, and food-grade silica gel is used for dehumidification to control moisture; finally, nitrogen filling ensures an oxygen concentration below 3%, guaranteeing quality throughout the entire process from processing to storage.

[0043] Example 1

[0044] This application provides a method for preparing matsutake mushroom powder by low-temperature drying, including the following steps:

[0045] S1. Raw material pretreatment: Fresh matsutake mushrooms transported via cold chain are washed with purified water, and then the washed fresh matsutake mushrooms are pulped under low temperature conditions to obtain matsutake mushroom pulp.

[0046] The fresh matsutake mushrooms are artificially cultivated matsutake mushrooms with a matsutake alcohol content of 0.35 ml / kg and a growth period of 7.5 days; the cleaning process uses a multi-stage spraying system with a water pressure of 0.35 MPa.

[0047] The pulping process is carried out in a high-speed, low-temperature pulper at a pulping temperature of 5°C, a pulping speed of 6500 rpm, a pulping time of 7.5 min, and a pulping particle size of 100 mesh.

[0048] Among them, the transportation temperature of cold chain transportation is controlled at 2℃, and the transportation time does not exceed 12 hours.

[0049] S2. Pulp pretreatment: The matsutake slurry is homogenized while inert gas is continuously introduced onto the surface of the slurry.

[0050] The homogenization process is carried out at a pressure of 27 MPa and 3 times. The inert gas is food-grade nitrogen with a flow rate of 10 L / min.

[0051] S3. Low-temperature drying: The matsutake mushroom pulp after S2 treatment is subjected to staged temperature-controlled drying to obtain matsutake mushroom powder.

[0052] The phased temperature-controlled drying process specifically includes:

[0053] First stage: Dry at 32.5℃ for 75 minutes;

[0054] Second stage: Raise the temperature to 38℃ and continue drying for 105 minutes;

[0055] The third stage: raise the temperature to 45.5℃ and dry until the moisture content of the slurry is less than 5 wt%.

[0056] After the second stage of drying is completed, the pressure control program is activated to reduce the pressure in the drying chamber from atmospheric pressure to -0.035 MPa within 5 minutes, and the third stage of drying is carried out under this pressure condition.

[0057] S4. Grinding and sieving: The dried matsutake powder is ground at a low temperature of 12.5℃, and then the ground matsutake powder is sieved using a 225-mesh vibrating sieve.

[0058] S5. Sterilization treatment: The sieved matsutake powder is subjected to non-thermal high-pressure sterilization and physical adsorption dehumidification treatment in sequence.

[0059] The non-thermal high-pressure sterilization process operates at a pressure of 450 MPa, a holding time of 4 minutes, and a processing temperature of 20°C.

[0060] Among them, the physical adsorption dehumidification treatment uses food-grade silica gel to treat matsutake powder. The amount of silica gel used is 7.5% of the mass of matsutake powder, and the treatment time is 20 seconds.

[0061] S6. Aseptic filling: The sterilized matsutake powder is filled and boxed in a nitrogen-filled environment, where the relative humidity of the filling environment is controlled below 25%.

[0062] The nitrogen-filled environment is created by filling the packaging container with nitrogen gas and controlling the oxygen volume concentration inside the container to be below 3%.

[0063] Example 2

[0064] This application provides a method for preparing matsutake mushroom powder by low-temperature drying, including the following steps:

[0065] S1. Raw material pretreatment: Fresh matsutake mushrooms transported via cold chain are washed with purified water, and then the washed fresh matsutake mushrooms are pulped under low temperature conditions to obtain matsutake mushroom pulp.

[0066] The fresh matsutake mushrooms are artificially cultivated matsutake mushrooms with a matsutake alcohol content of 0.2 ml / kg and a growth period of 6 days; the cleaning process uses a multi-stage spraying system with a water pressure of 0.2 MPa.

[0067] The pulping process is carried out in a high-speed, low-temperature pulper at a temperature of 0°C, a speed of 5000 rpm, a time of 5 minutes, and a particle size of 80 mesh.

[0068] Among them, the transportation temperature of cold chain transportation is controlled at 0℃, and the transportation time does not exceed 12 hours.

[0069] S2. Pulp pretreatment: The matsutake slurry is homogenized while inert gas is continuously introduced onto the surface of the slurry.

[0070] The homogenization process is carried out at a pressure of 20 MPa and is repeated twice. The inert gas is food-grade nitrogen, and the gas flow rate is 5 L / min.

[0071] S3. Low-temperature drying: The matsutake mushroom pulp after S2 treatment is subjected to staged temperature-controlled drying to obtain matsutake mushroom powder.

[0072] The phased temperature-controlled drying process specifically includes:

[0073] First stage: Dry at 30℃ for 60 minutes;

[0074] Second stage: Raise the temperature to 36℃ and continue drying for 90 minutes;

[0075] Third stage: Raise the temperature to 41℃ and dry until the moisture content of the slurry is less than 5wt%.

[0076] After the second stage of drying is completed, the pressure control program is activated to reduce the pressure in the drying chamber from atmospheric pressure to -0.02 MPa within 5 minutes, and the third stage of drying is carried out under this pressure condition.

[0077] S4. Grinding and sieving: The dried matsutake powder is ground at a low temperature of 10℃, and then the ground matsutake powder is sieved using a 200-mesh vibrating sieve.

[0078] S5. Sterilization treatment: The sieved matsutake powder is subjected to non-thermal high-pressure sterilization and physical adsorption dehumidification treatment in sequence.

[0079] The non-thermal high-pressure sterilization process operates at a pressure of 300 MPa, a holding time of 3 minutes, and a processing temperature of 15℃.

[0080] Among them, the physical adsorption dehumidification treatment uses food-grade silica gel to treat matsutake powder. The amount of silica gel used is 5% of the mass of matsutake powder, and the treatment time is 10 seconds.

[0081] S6. Aseptic filling: The sterilized matsutake powder is filled and boxed in a nitrogen-filled environment, where the relative humidity of the filling environment is controlled below 25%.

[0082] The nitrogen-filled environment is created by filling the packaging container with nitrogen gas and controlling the oxygen volume concentration inside the container to be below 3%.

[0083] Example 3

[0084] This application provides a method for preparing matsutake mushroom powder by low-temperature drying, including the following steps:

[0085] S1. Raw material pretreatment: Fresh matsutake mushrooms transported via cold chain are washed with purified water, and then the washed fresh matsutake mushrooms are pulped under low temperature conditions to obtain matsutake mushroom pulp.

[0086] The fresh matsutake mushrooms are artificially cultivated matsutake mushrooms with a matsutake alcohol content of 0.5 ml / kg and a growth period of 9 days; the cleaning process uses a multi-stage spraying system with a water pressure of 0.5 MPa.

[0087] The pulping process is carried out in a high-speed, low-temperature pulper at a pulping temperature of 10°C, a pulping speed of 8000 rpm, a pulping time of 10 minutes, and a pulping particle size of 120 mesh.

[0088] Among them, the transportation temperature of cold chain transportation is controlled at 4℃, and the transportation time does not exceed 12 hours.

[0089] S2. Pulp pretreatment: The matsutake slurry is homogenized while inert gas is continuously introduced onto the surface of the slurry.

[0090] The homogenization process is carried out at a pressure of 35 MPa and 4 cycles. The inert gas is food-grade argon with a flow rate of 15 L / min.

[0091] S3. Low-temperature drying: The matsutake mushroom pulp after S2 treatment is subjected to staged temperature-controlled drying to obtain matsutake mushroom powder.

[0092] The phased temperature-controlled drying process specifically includes:

[0093] First stage: Dry at 35℃ for 90 minutes;

[0094] Second stage: Raise the temperature to 40℃ and continue drying for 120 minutes;

[0095] Third stage: Raise the temperature to 50℃ and dry until the moisture content of the slurry is less than 5wt%.

[0096] After the second stage of drying is completed, the pressure control program is activated to reduce the pressure in the drying chamber from atmospheric pressure to -0.05 MPa within 5 minutes, and the third stage of drying is carried out under this pressure condition.

[0097] S4. Grinding and sieving: The dried matsutake powder is ground at a low temperature of 15℃, and then the ground matsutake powder is sieved using a 250-mesh vibrating sieve.

[0098] S5. Sterilization treatment: The sieved matsutake powder is subjected to non-thermal high-pressure sterilization and physical adsorption dehumidification treatment in sequence.

[0099] The non-thermal high-pressure sterilization process operates at a pressure of 600 MPa, a holding time of 5 minutes, and a processing temperature of 25°C.

[0100] Among them, the physical adsorption dehumidification treatment uses food-grade silica gel to treat matsutake powder. The amount of silica gel used is 10% of the mass of matsutake powder, and the treatment time is 30 seconds.

[0101] S6. Aseptic filling: The sterilized matsutake powder is filled and boxed in a nitrogen-filled environment, where the relative humidity of the filling environment is controlled below 25%.

[0102] The nitrogen-filled environment is created by filling the packaging container with nitrogen gas and controlling the oxygen volume concentration inside the container to be below 3%.

[0103] Comparative Example 1

[0104] The only difference from Example 1 is that in step S3, there is no staged temperature-controlled drying; instead, a traditional hot air oven is used to dry the product to the required moisture content in one go at 70°C. All other steps and parameters are the same as in Example 1.

[0105] Comparative Example 2

[0106] The only difference from Example 1 is that in step S3, the staged temperature-controlled drying is not performed. Instead, the traditional freeze-drying process is used, which involves pre-freezing at -40°C for 2 hours and then vacuum sublimation drying at 20-30°C for 10 hours. All other steps and parameters are the same as in Example 1.

[0107] Comparative Example 3

[0108] The only difference from Example 1 is that step S5 sterilization is omitted, while the remaining steps and parameters are the same as in Example 1.

[0109] Comparative Example 4

[0110] The only difference from Example 1 is that in step S2, no inert gas is introduced to the surface of the slurry; the other steps and parameters are the same as in Example 1.

[0111] Comparative Example 5

[0112] The only difference from Example 1 is that physical adsorption dehumidification is not performed in step S5, while the other steps and parameters are the same as in Example 1.

[0113] Comparative Example 6

[0114] The only difference from Example 1 is that in step S5, non-thermal high-pressure sterilization is not performed; instead, conventional thermal sterilization is used at 80°C for 30 minutes. All other steps and parameters are the same as in Example 1.

[0115] I. Experiment on the determination of matsutake alcohol retention rate

[0116] Take 5.0 g of each of the matsutake powder prepared in Examples 1-3 and Comparative Examples 1-6, place them in 50 mL stoppered centrifuge tubes, add 20 mL of anhydrous ethanol, and extract by ultrasonication for 30 min at room temperature. The ultrasonic power is set to 300 W and the ultrasonic frequency is 40 kHz. After extraction, centrifuge at 8000 rpm for 15 min, and filter the supernatant through a 0.22 μm organic phase filter membrane to obtain the sample solution to be tested. The content of matsutake alcohol in the sample solution is determined by high performance liquid chromatography (HPLC). The chromatographic conditions are as follows: C18 column, mobile phase is methanol-water (volume ratio of methanol to water 85:15), flow rate is controlled at 1.0 mL / min, column temperature is set at 30℃, detection wavelength is 220 nm, and injection volume is 10 μL. A standard curve is plotted based on the peak area of ​​the matsutake alcohol standard, and the corresponding matsutake alcohol concentration is found from the standard curve based on the peak area of ​​the sample solution to be tested. The actual content of matsutake alcohol in each matsutake powder sample is then calculated. Finally, based on the theoretical content of matsutake alcohol in Example 1, where the theoretical content was calculated according to the matsutake alcohol content in fresh matsutake mushrooms and the material loss during the preparation process, the matsutake alcohol retention rate of matsutake powder in each example and comparative example was calculated. By comparing the retention rates of different samples, the influence of different preparation methods on the retention effect of matsutake alcohol, a key nutrient in matsutake powder, was evaluated. The formula for calculating the retention rate is as follows:

[0117] II. Microbial Indicator Detection Experiment

[0118] Accurately weigh 25.0 g each of the matsutake powder samples from Examples 1-3 and Comparative Examples 1-6, and place them in a homogenization bag containing 225 mL of sterile physiological saline. Homogenize in a sterile homogenizer for 1 min to prepare a 1:10 sample homogenate. Then, following aseptic operation requirements, serially dilute the sample homogenate to prepare homogenates of different dilutions, such as 1:100 and 1:1000. Take 1 mL of each dilution and inject it into a sterile petri dish, making 3 replicates for each dilution. For the determination of total colony count, pour approximately 15 mL of melted and cooled nutrient agar medium to 46°C into the petri dish, gently shake to mix, and after the medium solidifies, invert the dish and incubate in a constant temperature incubator at 36°C ± 1°C for 48 h ± 2 h. After incubation, count the number of colonies in each petri dish and calculate the total colony count per gram of matsutake powder. For the determination of coliform bacteria, about 15 mL of melted and cooled VRBA medium to 46°C was poured into a petri dish, gently shaken, and after the medium solidified, a layer of the same medium was covered on the surface. The dish was then inverted and placed in a constant temperature incubator at 36°C±1°C for 24h±2h. Based on the number and characteristics of typical colonies that appeared after incubation, the number of coliform bacteria per 100g of matsutake mushroom powder was calculated according to the coliform bacteria counting method. By detecting the microbial indicators of different samples, the sterilization effect of each preparation method and the hygiene and safety of the product were judged.

[0119] III. Experiment on Moisture Content and Hygroscopicity Determination

[0120] Moisture content determination: Weigh 2.0 g each of the matsutake powder samples from Examples 1-3 and Comparative Examples 1-6, and place them in weighing bottles that have been dried to constant weight in an oven at 105℃±2℃. Accurately weigh the total mass and record it as m1. Then place the weighing bottles in a constant temperature oven at 105℃±2℃, open the caps, and dry for 4 hours. After that, close the caps and place the bottles in a desiccator to cool for 30 minutes. Accurately weigh the bottles again and record the mass as m2. Calculate the moisture content using the formula: Calculate the initial moisture content of each sample.

[0121] Hygroscopicity determination: After determining the initial moisture content of each matsutake mushroom powder sample, it was placed in a constant temperature and humidity chamber at 25℃±1℃ and 75%±2% relative humidity. After 1, 3, 5, and 7 days, the samples were removed, and the moisture content was determined again at each time point using the same method as described above. A hygroscopicity curve was plotted with the placement time on the x-axis and the sample moisture content on the y-axis. By comparing the initial moisture content and the trend of the hygroscopicity curves of different samples, the impact of each preparation method on the moisture control and storage stability of the matsutake mushroom powder was evaluated.

[0122] The experimental data for the determination of matsutake alcohol retention rate are shown in Table 1.

[0123] Table 1:

[0124]

[0125]

[0126] The experimental data for the detection of microbial indicators are shown in Table 2.

[0127] Table 2:

[0128] Sample number Total bacterial count (CFU / g) Coliform bacteria (CFU / 100g) Example 1 85 Not detected Example 2 92 Not detected Example 3 78 Not detected Comparative Example 1 156 Not detected Comparative Example 2 103 Not detected Comparative Example 3 2850 95 Comparative Example 4 98 Not detected Comparative Example 5 82 Not detected Comparative Example 6 121 Not detected

[0129] The experimental data for moisture content and hygroscopicity determination are shown in Table 3.

[0130] Table 3:

[0131]

[0132]

[0133] Based on Examples 1-3 and Comparative Example 1, and in conjunction with Tables 1 and 3, it can be seen that compared to the staged temperature-controlled drying method used in the Examples, the traditional hot air oven used in Comparative Example 1, which dries the product in one go, is prone to degradation of the heat-sensitive component matsutake alcohol in matsutake mushrooms due to the high temperature and lack of gradient temperature control design during the drying process. At the same time, the high drying temperature also causes the material to lose moisture quickly, damaging the internal structure of the powder and affecting the hygroscopic stability of the powder, making the product more likely to absorb moisture from the environment during subsequent storage.

[0134] Based on Examples 1-3 and Comparative Example 2, and in conjunction with Tables 1 and 3, it can be seen that although the traditional freeze-drying method used in Comparative Example 2 can dry at a lower temperature and reduce the loss of some heat-sensitive components, this process requires low-temperature pre-freezing followed by vacuum sublimation drying, which is relatively complex. Furthermore, the pre-freezing process may have a certain impact on the microstructure of the matsutake mushroom pulp. In terms of subsequent moisture control, compared with the staged temperature-controlled drying of the examples, it did not show better performance in terms of long-term moisture absorption stability. This may be related to the difference in the porous structure of the powder after freeze-drying and the thoroughness of moisture removal during the drying process.

[0135] As can be seen from Examples 1-3 and Comparative Example 3, and in conjunction with Table 2, all examples included a sterilization process combining non-thermal high-pressure sterilization and physical adsorption dehumidification. However, Comparative Example 3 omitted this step, resulting in the loss of effective control over microorganisms in the product. Microorganisms can multiply rapidly under suitable conditions, leading to a significant increase in the total bacterial count and potentially exceeding the standard for coliform bacteria. This not only affects the hygiene and safety of the product but may also cause product spoilage during storage due to microbial activity, damaging the nutritional components and sensory quality of the matsutake mushroom powder.

[0136] Based on Examples 1-3 and Comparative Example 4, and in conjunction with Table 1, it can be seen that in Examples 1-3, inert gas was introduced onto the surface of the slurry during homogenization, which isolated the air and reduced the contact between the slurry and oxygen, thereby reducing the probability of matsutake alcohol loss due to oxidation. In contrast, Comparative Example 4 did not introduce inert gas, and the slurry was in direct contact with air during the processing. Matsutake alcohol was more likely to react with oxygen, resulting in a decrease in the retention rate of matsutake alcohol in the final product. This indicates that the protective effect of inert gas is indispensable in maintaining the key nutrients of matsutake powder.

[0137] Based on Examples 1-3 and Comparative Example 5, and in conjunction with Table 3, it can be seen that the Examples, through physical adsorption dehumidification treatment, can further remove residual moisture in the sieved matsutake powder, reduce the initial moisture content of the product, and reduce the moisture absorption sites on the powder surface. In contrast, Comparative Example 5 did not undergo this treatment, resulting in a relatively high initial moisture content. Furthermore, during subsequent storage, due to the lack of adsorption dehumidification protection, it is more likely to absorb moisture from the environment, leading to a rapid increase in moisture content. This, in turn, affects the storage stability of the product and may shorten its shelf life.

[0138] Based on Examples 1-3 and Comparative Example 6, and in conjunction with Tables 1 and 2, it can be seen that the non-thermal high-pressure sterilization used in the examples is carried out at a lower temperature, which can effectively kill microorganisms while minimizing the damage of heat-sensitive nutrients such as matsutake alcohol to high temperatures. In contrast, the traditional thermal sterilization used in Comparative Example 6 requires continuous treatment at a higher temperature for a period of time. Although it can achieve a certain sterilization effect, the high-temperature environment will cause matsutake alcohol to degrade, reducing its retention rate. This shows that non-thermal high-pressure sterilization has a more obvious advantage in balancing product hygiene and safety with nutrient retention.

[0139] This specific embodiment is merely an explanation of this application and is not intended to limit it. After reading this specification, those skilled in the art can make modifications to this embodiment without contributing any inventive step, but such modifications are protected by patent law as long as they fall within the scope of the claims of this application.

Claims

1. A method for preparing matsutake mushroom powder by low-temperature drying, characterized in that: Includes the following steps: S1. Raw material pretreatment: Fresh matsutake mushrooms transported via cold chain are washed with purified water, and then the washed fresh matsutake mushrooms are pulped under low temperature conditions to obtain matsutake mushroom pulp. S2. Pulp pretreatment: The matsutake slurry is homogenized while inert gas is continuously introduced onto the surface of the slurry. S3. Low-temperature drying: The matsutake mushroom pulp after S2 treatment is subjected to staged temperature-controlled drying to obtain matsutake mushroom powder. S4. Grinding and sieving: Grind the dried matsutake powder at a low temperature of 10-15℃, and then sieve the ground matsutake powder using a 200-250 mesh vibrating screen. S5. Sterilization treatment: The sieved matsutake powder is subjected to non-thermal high-pressure sterilization and physical adsorption dehumidification treatment in sequence. S6. Aseptic filling: The sterilized matsutake powder is filled and boxed in a nitrogen-filled environment, where the relative humidity of the filling environment is controlled below 25%.

2. The method for preparing matsutake mushroom powder by low-temperature drying according to claim 1, characterized in that: In step S1, the fresh matsutake mushrooms are artificially cultivated matsutake mushrooms with a matsutake alcohol content of 0.2-0.5 ml / kg and a growth period of 6-9 days; the cleaning is carried out using a multi-stage spraying device with a water pressure of 0.2-0.5 MPa.

3. The method for preparing matsutake mushroom powder by low-temperature drying according to claim 1, characterized in that: In step S1, the pulping is carried out in a high-speed low-temperature pulper, with a pulping temperature of 0-10℃, a pulping speed of 5000-8000 rpm, a pulping time of 5-10 min, and a pulping particle size of 80-120 mesh.

4. The method for preparing matsutake mushroom powder by low-temperature drying according to claim 1, characterized in that: In step S1, the transport temperature of the cold chain transportation is controlled at 0-4℃, and the transport time does not exceed 12 hours.

5. The method for preparing matsutake mushroom powder by low-temperature drying according to claim 1, characterized in that: In step S2, the homogenization treatment pressure is 20-35 MPa, and the number of cycles is 2-4; the inert gas is food-grade nitrogen or argon, and the gas flow rate is 5-15 L / min.

6. The method for preparing matsutake mushroom powder by low-temperature drying according to claim 1, characterized in that: In step S3, the staged temperature-controlled drying process specifically includes: First stage: Dry at 30-35℃ for 60-90 minutes; Second stage: Raise the temperature to 36-40℃ and continue drying for 90-120 minutes; The third stage: raise the temperature to 41-50℃ and dry until the moisture content of the slurry is less than 5wt%.

7. The method for preparing matsutake mushroom powder by low-temperature drying according to claim 6, characterized in that: After the second stage of drying is completed, the pressure control program is activated to reduce the pressure in the drying chamber from atmospheric pressure to -0.02 MPa to -0.05 MPa within 5 minutes, and the third stage of drying is carried out under this pressure condition.

8. The method for preparing matsutake mushroom powder by low-temperature drying according to claim 1, characterized in that: In step S5, the working pressure of the non-thermal high-pressure sterilization is 300-600MPa, the holding time is 3-5min, and the processing temperature is 15-25℃.

9. The method for preparing matsutake mushroom powder by low-temperature drying according to claim 1, characterized in that: In step S5, the physical adsorption dehumidification treatment involves treating the matsutake powder with food-grade silica gel. The amount of silica gel used is 5-10% of the mass of the matsutake powder, and the treatment time is 10-30 seconds.

10. The method for preparing matsutake mushroom powder by low-temperature drying according to claim 1, characterized in that: In step S6, the nitrogen-filled environment is formed by filling the packaging container with nitrogen gas and controlling the oxygen volume concentration in the container to be below 3%.

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