A mycelium composite packaging material based on Ganoderma lucidum strains and its preparation method

Abstract

This invention discloses a mycelial composite packaging material based on Ganoderma lucidum strains and its preparation method, belonging to the field of packaging material technology. The method includes five-stage subculturing activation of Ganoderma lucidum strains using PDA medium, preparation and inoculation of soybean straw substrate, primary mold culture, secondary sealed culture, and gradient drying treatment. This invention ensures high viability and stability of the strains through five-stage subculturing, promotes free mycelial growth and surface mycelial film formation through secondary sealed culture, further improving the structural integrity and mechanical strength of the material and avoiding yellowing caused by surface water droplet accumulation. The gradient drying process effectively avoids Maillard reactions and surface scorching, while also effectively reducing shrinkage during the drying process, significantly improving the overall performance of the Ganoderma lucidum mycelium and soybean straw composite material.

Description

Technical Field

[0001] This invention relates to the field of packaging materials technology, specifically to a mycelium composite packaging material based on Ganoderma lucidum strains and its preparation method. Background Technology

[0002] Mycelial composite materials are a new type of environmentally friendly material, composed of fungal mycelia and fibrous materials rich in organic nutrients such as lignin. Compared with traditional packaging materials, mycelial composite materials have many advantages, such as wide availability of resources, low cost, low energy consumption, no pollution, and easy degradation. Therefore, they have broad application potential in packaging, construction, thermal insulation, noise reduction, and other fields.

[0003] The microstructure of mycelial composite materials exhibits a multi-layered three-dimensional network structure, with mycelia enveloping matrix fibers. The interaction between mycelia and the matrix, as well as the mechanical properties of the mycelia themselves, jointly determine the mechanical properties of the material. Fungal species mainly originate from the Basidiomycota phylum, and most of these species possess the ability to decompose and utilize lignin and cellulose. The matrix sources for mycelial composite materials are abundant, commonly including agricultural byproducts, industrial waste, and post-consumer waste. Different matrix types have a significant impact on the physical and mechanical properties of the material.

[0004] The invention patent with publication number CN115746386B discloses a composite material obtained by mixing and cultivating fungi such as Ganoderma lucidum and oyster mushroom with bean straw, which has significant advantages in terms of compressive strength and flexural strength (the compressive strength reaches 80.18 kPa and the flexural load reaches 22.83 N).

[0005] Key issues for expanding the application of mycelial composite materials include: the network strength between the specific fungal species used in material preparation and the matrix still needs to be enhanced; and the mechanical properties, shrinkage rate, and aesthetics of the composite materials need to be improved. Summary of the Invention

[0006] To achieve the above objectives, the present invention provides the following technical solution:

[0007] A method for preparing a Ganoderma lucidum mycelium composite packaging material includes the following steps:

[0008] Step 1: Use PDA medium to activate Ganoderma strains through five levels of subculturing. After the five levels of subculturing are completed, store the cultured PDA culture dishes in a 4°C refrigerator for later use, so as to facilitate subsequent substrate inoculation.

[0009] Step 2: Preparation and inoculation of soybean straw substrate. The mass percentage of each raw material in the substrate is: 31.2% soybean straw, 8% wheat bran, 0.4% lime, 0.4% gypsum, and 60% pure water. After thoroughly mixing these raw materials, fill them into mushroom bags. After bagging, sterilize the substrate at 121℃ for 60 minutes, and then place the substrate in a laminar flow hood to cool to room temperature. Then, take the Ganoderma lucidum strain blocks after five generations from the PDA culture dish, and use sterilized inoculation tools to inoculate the whole block into the soybean straw substrate that has cooled to room temperature in the laminar flow hood. Place the soybean straw mushroom bags in a 28℃ constant temperature incubator for cultivation under dark conditions for 15 to 25 days, until the surface of the mushroom bags is completely covered with white mycelium. After cultivation, transfer the soybean straw mushroom bags covered with mycelium to a 4℃ refrigerator for storage.

[0010] Step 3, one-time incubation: Place the soybean straw spawn bag obtained in step 2 into a clean bench, tear off the spawn bag, and use a crusher to crush the soybean straw spawn bag into uniform particles, ensuring uniform particle size and no obvious lumps. Then, put the mixture containing mycelium and substrate into a plastic culture box, use a flattener to flatten the surface, ensuring uniform substrate distribution, seal the plastic culture box, and place the plastic culture box in a constant temperature and humidity dark incubator for three days of incubation.

[0011] Step 4, secondary sealed culture: Demold the material that has been cultured for three days in Step 3, put the demolded material into a larger sealed container, and let it stand for three more days. Wipe the surface of the material to remove moisture every day during the culture period.

[0012] Step 5: Gradient drying treatment. After secondary sealed cultivation, the material is first dried at 45℃ for 30 minutes to remove surface moisture until the surface mycelium is not easily rubbed off and is slightly dry. Then, the temperature is raised to 65℃ and dried for another 48 hours until the material reaches constant weight, thus obtaining mycelium composite packaging material.

[0013] As a preferred embodiment, step 1 specifically involves:

[0014] In each subculture operation, light an alcohol lamp and flammate the tweezers. Use a sterile inoculation hook to pick up a bacterial block from the culture tube and inoculate it into the center of the PDA culture dish. After sealing with sealing film, place the PDA culture dish in a 28°C constant temperature incubator for 3 days. Then use the same subculture method to carry out the next generation of subculture until five subcultures are completed. After the five subcultures are completed, store the cultured PDA culture dishes in a 4°C refrigerator for later use, which will facilitate subsequent substrate inoculation.

[0015] Preferably, the Ganoderma strain in step 1 is one of GY1, GY2, GY3 and GY4.

[0016] Preferably, the PDA culture medium in step 1 is as follows:

[0017] Take 200g of fresh, peeled potatoes, cut them into chunks, and boil them with 1000mL of water for 15 minutes. Then filter the mixture through gauze to obtain potato extract. Add 20g of glucose and 20g of agar to the potato extract, heat until completely dissolved, and then add water to 1000mL. Seal the mixture with sealing film and sterilize it. After sterilization, dispense the mixture into sterile petri dishes while still hot. After cooling, the PDA culture medium is obtained.

[0018] The present invention also provides a mycelium composite packaging material based on Ganoderma lucidum strains, which is prepared by the preparation method described above.

[0019] The present invention has the following beneficial effects:

[0020] This invention significantly improves the overall performance of Ganoderma lucidum mycelium and soybean straw composite materials through a five-stage subculturing technique, a closed secondary culture, and a gradient drying process. First, the five-stage subculturing technique activates the mycelium, ensuring high viability and stability across multiple generations, thereby enhancing the material's uniformity and mechanical properties. In particular, the GY1 strain exhibits excellent growth rate, surface uniformity, and mechanical properties, making it the core strain for material preparation. Second, the closed secondary culture method effectively promotes free mycelial growth and the formation of a surface mycelial film, further improving the material's structural integrity and mechanical strength, avoiding yellowing caused by surface water droplet accumulation, and ensuring the material's appearance and stability. Finally, the gradient drying process, through a gradual increase in temperature from low (45℃) to high (65℃), effectively avoids Maillard reactions and surface scorching, while also effectively reducing the shrinkage rate during drying from approximately 10% under traditional processes to 4%–6%, thus further improving the dimensional stability and consistency of the finished product.

[0021] The composite packaging material obtained by co-culturing GY1 and soybean straw in this invention reaches the maximum stress at a strain of 0.1, showing strong compressive strength with a maximum compressive strength of 120 kPa. The composite packaging material obtained by co-culturing GY1 and soybean straw has a maximum bending load of 36.84 N, which greatly improves the performance and stability of mycelial composite materials and provides a green, efficient, environmentally friendly and sustainable solution for their application in packaging, construction and other fields. Attached Figure Description

[0022] Figure 1 This is a growth diagram of the material cultured in this invention for 3 days after a single incubation.

[0023] Figure 2 This is a growth diagram of the secondary closed culture for 3 days in this invention;

[0024] Figure 3 These are images showing the apparent morphology of composite materials obtained by different drying methods in this invention.

[0025] Figure 4 This is a comparison chart of the shrinkage rates of composite materials obtained by the two drying methods in this invention;

[0026] Figure 5 This is a diagram showing the appearance morphology after gradient drying in this invention;

[0027] Figure 6 This is a comparison diagram of stress-strain curves of different mycelial composite packaging materials in this invention;

[0028] Figure 7 This is a comparison diagram of the bending properties of different mycelial composite packaging materials in this invention;

[0029] Figure 8 This is a schematic flowchart of a method for preparing a mycelium composite packaging material based on Ganoderma lucidum strains according to the present invention. Detailed Implementation

[0030] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0031] This invention utilizes GY1, GY2, GY3, and GY4 to prepare mycelial composite packaging materials, wherein GY1 is Ganoderma lucidum (purple), GY2 is Ganoderma lucidum (black), GY3 is Ganoderma lucidum (red), and GY4 is Ganoderma sinense (red). The invention will be further described in detail below with reference to the accompanying drawings and embodiments.

[0032] Example 1: A method for preparing a mycelium composite packaging material based on Ganoderma lucidum strains, comprising the following steps:

[0033] Step 1: Use PDA medium to activate Ganoderma strain GY1 through five subcultures. In each subculture, light an alcohol lamp and flammate the tweezers. Use a sterile inoculation hook to pick up a mycelial block (a mycelial block refers to a mixture of mycelium containing fungal mycelium and nutrients and PDA medium) from the culture tube and inoculate it into the center of the PDA culture dish. Seal the dish with sealing film and record the strain information and date. Place the PDA culture dish in a 28°C incubator for 3 days. After the mycelium has grown to a certain extent, use the same subculture method to carry out the next generation of subcultures until the five subcultures are completed. After the five subcultures are completed, store the cultured PDA culture dishes in a 4°C refrigerator for later use, which will facilitate subsequent substrate inoculation.

[0034] In the preparation of PDA culture medium, 200g of fresh peeled potatoes were taken, cut into pieces, and boiled with 1000mL of water for 15 minutes. Then, the mixture was filtered through gauze to obtain potato extract. 20g of glucose and 20g of agar were added to the potato extract and heated until completely dissolved. Water was added to 1000mL, and the mixture was sealed with sealing film and sterilized. After sterilization, it was dispensed into sterile petri dishes while still hot and cooled to obtain PDA culture medium.

[0035] Step 2: Preparation and inoculation of soybean straw substrate. The mass percentage of each raw material in the substrate is: 31.2% soybean straw, 8% wheat bran, 0.4% lime, 0.4% gypsum, and 60% pure water. After thoroughly mixing these raw materials, fill them into mushroom bags, 600g per bag. After bagging, sterilize the substrate at 121℃ for 60 minutes to ensure sterility. Then, place the substrate in a laminar flow hood to cool to room temperature. Next, remove the GY1 mycelium blocks after five generations from the PDA culture dish and, using sterilized inoculation tools, inoculate the entire mycelium block into the cooled soybean straw substrate in the laminar flow hood. Place the soybean straw mycelium bags in a 28℃ constant temperature incubator for cultivation under dark conditions for 15 to 25 days, until the surface of the mycelium bags is completely covered with white mycelium. After cultivation, transfer the soybean straw mycelium-covered bags to a 4℃ refrigerator for storage.

[0036] Step 3: Initial incubation. Place the soybean straw spawn bags obtained in Step 2 into a clean bench, tear off the bags, and use a crusher to break the soybean straw spawn bags into uniform particles, ensuring uniform particle size and no obvious lumps. Then, place the mixture containing mycelium and substrate into a plastic culture box, use a flattener to flatten the surface, ensuring even distribution of the substrate, seal the plastic culture box and label it, then place the plastic culture box in a constant temperature, humidity, and light-proof incubator for three days of incubation (the growth status after 3 days can be referenced). Figure 1 );

[0037] Step 4, secondary sealed cultivation: Demold the material that has been cultivated for three days in Step 3, and place the demolded material into a slightly larger sealed container. By increasing the oxygen supply and providing more growth space for the mycelium, the mycelium is promoted to regrow and form a complete mycelial film, which enhances the mechanical strength and stability of the material. Then, let it stand for another three days. During the cultivation period, wipe the surface of the material to remove moisture every day to avoid water droplets accumulating and causing yellowing of the surface, keep the material clean, and avoid the stability of the material due to moisture.

[0038] Step 5, gradient drying treatment: After secondary sealed cultivation, the material is first dried at 45℃ for 30 minutes to remove surface moisture, until the surface mycelium is not easily rubbed off and is slightly dry. Then, the temperature is raised to 65℃ and dried for another 48 hours until the material reaches constant weight, thus obtaining mycelium composite packaging material. The key to gradient drying is to control the temperature to gradually increase, avoiding excessively high temperatures that could trigger the Maillard reaction and cause the material surface to turn yellow.

[0039] Example 2: This example is based on Example 1, but differs from Example 1 in that step 5 uses a constant temperature drying method, drying at 80°C for 24 hours until the material reaches constant weight, thus obtaining mycelium composite packaging material.

[0040] The appearance of the mycelium composite packaging material obtained in this embodiment (constant temperature drying) is similar to that of the mycelium composite packaging material obtained in Example 1 (gradient drying). Figure 3 As shown ( Figure 3 In the diagram, A represents drying at 80 degrees Celsius without gradient drying, and B represents drying at 45-65 degrees Celsius with gradient drying. The linear shrinkage rate was calculated by measuring the length, width, and thickness before and after drying, and the results are as follows: Figure 4 As shown, the shrinkage rate of constant temperature drying is about 10%, while the shrinkage rate is significantly reduced to between 4% and 6% after gradient drying. This shows that gradient drying effectively reduces the shrinkage and deformation of materials during the drying process, and improves the dimensional stability of materials and the consistency of finished products.

[0041] Example 3: This example is based on Example 1, but differs from Example 1 in that GY1 in step 1 is replaced with GY2, and the corresponding mycelium composite packaging material is obtained after gradient drying treatment.

[0042] Example 4: This example is based on Example 1, but differs from Example 1 in that GY1 in step 1 is replaced with GY3, and the corresponding mycelium composite packaging material is obtained after gradient drying treatment.

[0043] Example 5: This example is based on Example 1, but differs from Example 1 in that GY1 in step 1 is replaced with GY4, and the corresponding mycelium composite packaging material is obtained after gradient drying treatment.

[0044] In Examples 1 and 3 to 5, the appearances of the four mycelial composite packaging materials prepared corresponding to GY1, GY2, GY3, and GY4 are as follows: Figure 5 As shown, the low temperature (45℃) during gradient drying helps maintain the integrity of the mycelial structure, while the high temperature (65℃) can effectively remove moisture from the material, ensuring uniform drying, material stability, and controlling the shrinkage rate of the material at the same time.

[0045] After the above four mycelial composite packaging materials (corresponding to GY1, GY2, GY3, and GY4 respectively) were dried to constant weight, they were placed at room temperature of 25°C for 24 hours to adjust their condition. Subsequently, bending and compression performance tests were conducted according to GBT 8812.1-2007 and GBT 8813-2020 standards. Each test was repeated 3 times to ensure the accuracy and comparability of the data.

[0046] The results showed that the composite materials prepared by different strains had significant differences in mechanical properties. Among them, the reference... Figure 6 The mycelium composite packaging materials prepared by GY1 and GY2 exhibited high stress values ​​in the compressive stress-strain curve. In particular, the composite packaging material obtained by co-culturing GY1 with soybean straw reached its maximum stress at a strain of 0.1, demonstrating strong compressive strength. The highest compressive strength reached 120 kPa, and the compressive performance was significantly improved by approximately 49% compared to the existing technology (CN115746386B). (Reference) Figure 7 In terms of bending performance, the fracture loads of GY1 and GY2 are significantly higher than those of GY3 and GY4. The composite packaging material obtained by co-cultivating GY1 with soybean straw has a bending load of up to 36.84 N, which is about 61% higher than that of the existing technology (CN115746386B). Meanwhile, reference... Figure 4 The shrinkage rate of the composite packaging material obtained by co-culturing GY1 with soybean straw can be controlled at 4% to 6%, and it has high surface whiteness, good flatness, and good wrapping properties (reference). Figure 5 The mycelium composite packaging material prepared by this invention can be applied to a variety of products such as aromatherapy boxes, ashtray trays, and strawberry fruit packaging trays.

[0047] In summary, this invention combines five-stage subculturing activation technology, closed secondary culture, and gradient drying process to effectively improve the performance and stability of the material. Among the Ganoderma lucidum strains used (GY1, GY2, GY3, and GY4), strain GY1 showed the best performance in terms of surface uniformity and mechanical properties (flexibility and compressibility). The five-stage subculturing technology successfully improved the vigor and stability of the strains, ensuring the uniformity of the material; the closed secondary culture optimized mycelial growth, ensuring surface uniformity and avoiding yellowing caused by excessive moisture; and the gradient drying process overcame the defects of traditional constant-temperature drying, which easily leads to surface damage and severe shrinkage, achieving dual optimization of the material's appearance and dimensions.

[0048] Among these, closed secondary cultivation is crucial for improving the overall performance of the material, mainly in the following three aspects:

[0049] Improve surface coverage: This allows the mycelium to grow fully, forming a uniform and complete film, thereby improving the structural strength and aesthetics of the material;

[0050] Enhancing material strength: In a closed environment, mycelia can extend outward and firmly bind to the substrate, forming a robust network structure that enhances the mechanical properties of the material;

[0051] Reduce moisture buildup: Wipe away surface moisture daily to prevent water droplets from accumulating and causing yellowing, keep the material clean, and avoid affecting the material's stability due to moisture.

[0052] The method for preparing mycelium composite packaging materials provided by this invention simplifies the process while reducing costs, improving aesthetics, mechanical properties, and dimensional stability, providing an efficient, environmentally friendly, and economical solution for the industrial mass production of composite materials. The mycelium composite packaging materials provided by this invention have significant advantages in mechanical properties and sustainability, and have good prospects for industrial application, especially showing broad application potential in the field of green packaging.

[0053] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A method for preparing a mycelial composite packaging material based on Ganoderma lucidum strains, characterized in that, Includes the following steps: Step 1: Use PDA medium to activate Ganoderma strains through five levels of subculturing. After the five levels of subculturing are completed, store the cultured PDA culture dishes in a 4°C refrigerator for later use, so as to facilitate subsequent substrate inoculation. Step 2: Preparation and inoculation of soybean straw substrate. The mass percentage of each raw material in the substrate is: 31.2% soybean straw, 8% wheat bran, 0.4% lime, 0.4% gypsum, and 60% pure water. After thoroughly mixing these raw materials, fill them into mushroom bags. After bagging, sterilize the substrate at 121℃ for 60 minutes, and then place the substrate in a laminar flow hood to cool to room temperature. Then, take the Ganoderma lucidum strain blocks after five generations from the PDA culture dish, and use sterilized inoculation tools to inoculate the whole block into the soybean straw substrate that has cooled to room temperature in the laminar flow hood. Place the soybean straw mushroom bags in a 28℃ constant temperature incubator for cultivation under dark conditions for 15 to 25 days, until the surface of the mushroom bags is completely covered with white mycelium. After cultivation, transfer the soybean straw mushroom bags covered with mycelium to a 4℃ refrigerator for storage. Step 3, one-time incubation: Place the soybean straw spawn bag obtained in step 2 into a clean bench, tear off the spawn bag, and use a crusher to crush the soybean straw spawn bag into uniform particles, ensuring uniform particle size and no obvious lumps. Then, put the mixture containing mycelium and substrate into a plastic culture box, use a flattener to flatten the surface, ensuring uniform substrate distribution, seal the plastic culture box, and place the plastic culture box in a constant temperature and humidity dark incubator for three days of incubation. Step 4, secondary sealed culture: Demold the material that has been cultured for three days in Step 3, put the demolded material into a larger sealed container, and let it stand for three more days. Wipe the surface of the material to remove moisture every day during the culture period. Step 5, gradient drying treatment: After secondary sealed cultivation, the material is first dried at 45℃ for 30 minutes to remove surface moisture until the surface mycelium is not easily rubbed off and is slightly dry. Then, the temperature is raised to 65℃ and dried for another 48 hours until the material reaches constant weight, thus obtaining mycelium composite packaging material. The Ganoderma strains mentioned are Ganoderma lucidum, Ganoderma sinense, and Ganoderma rubrum.

2. The method for preparing a mycelial composite packaging material based on Ganoderma lucidum strain according to claim 1, characterized in that, Step 1 is as follows: In each subculture operation, light an alcohol lamp and flammate the tweezers. Use a sterile inoculation hook to pick up a bacterial block from the culture tube and inoculate it into the center of the PDA culture dish. After sealing with sealing film, place the PDA culture dish in a 28°C constant temperature incubator for 3 days. Then use the same subculture method to carry out the next generation of subculture until five subcultures are completed. After the five subcultures are completed, store the cultured PDA culture dishes in a 4°C refrigerator for later use, which will facilitate subsequent substrate inoculation.

3. The method for preparing a mycelial composite packaging material based on Ganoderma lucidum strain according to claim 2, characterized in that, The PDA culture medium in step 1 is specifically as follows: Take 200g of fresh, peeled potatoes, cut them into chunks, and boil them with 1000mL of water for 15 minutes. Then filter the mixture through gauze to obtain potato extract. Add 20g of glucose and 20g of agar to the potato extract, heat until completely dissolved, and then add water to 1000mL. Seal the mixture with sealing film and sterilize it. After sterilization, dispense the mixture into sterile petri dishes while still hot. After cooling, the PDA culture medium is obtained.

4. A mycelial composite packaging material based on Ganoderma lucidum strains, characterized in that, It is prepared by the preparation method according to any one of claims 1 to 3.

Images