Method for producing an internally gelled mycelium composite material and a mycelium composite material produced thereby

Abstract

The present invention relates to a technology for manufacturing a mycelial composite material using an internal gelation method. More specifically, by applying a non-carbonate calcium salt instead of calcium carbonate as a curing initiator, carbon dioxide is not generated during the gelation process, thereby preventing expansion or deformation of the molded body and securing a uniform initial structure, a technology is provided that enables the production of a stable mycelial composite material through external culture alone.

Description

Technology Field

[0001] The present invention relates to a method for manufacturing a composite material using mycelium and a mycelium composite material manufactured thereby. More specifically, it relates to a mycelium composite material manufactured by forming a molded body using an internal gelling method with a gelling agent and then culturing it externally, and a method for manufacturing the same.

[0002] In particular, the present invention relates to a mycelial composite material and a method for manufacturing the same, which improves molding stability and shape precision by using a non-carbonate calcium salt that dissolves in acid as a curing initiator to induce internal gelation without generating carbon dioxide. Background Technology

[0003] The technology for manufacturing biodegradable materials using mycelium has recently been attracting attention in various industrial fields, and a method of growing mycelium in a medium based on agricultural byproducts to form a fibrous network is widely used.

[0004] In general manufacturing processes, a method is primarily used in which mycelia are cultured inside the mold for a considerable period after filling the mold with a culture medium to maintain the shape of the molded body, and additionally external culture is performed to secure mechanical strength and structural completeness. While this process has the advantage of being relatively stable, there are problems such as limited production efficiency and low mold turnover due to the long duration required for internal culture.

[0005] To overcome these limitations, a technology has been proposed to produce the material using only external culture after imparting a certain strength immediately after molding using an internal gelation reaction. In particular, various studies are being conducted on gelation methods utilizing cross-linking between sodium alginate and calcium ions, as they allow for easy control of the viscosity of the culture medium and the formation of a stable structure during the molding stage.

[0006] Traditionally, calcium carbonate was primarily used as a source of calcium ions, and through acidification, Ca 2+A method has been applied to induce internal gelation by allowing the carbon dioxide to be released slowly. However, calcium carbonate-based methods may involve a reaction mechanism in which carbon dioxide is generated during the acidification process, which can lead to problems such as the formation of bubbles or expansion within the molded body, making it difficult to maintain the desired shape.

[0007] In addition, it is known that the generation of such bubbles impairs the uniformity of the internal gel network, which can negatively affect structural stability and mechanical properties during the external culture process. This problem is even more pronounced in products requiring complex shapes or dimensional precision.

[0008] Therefore, there is a continuous need for a technology that can form a uniform internal gel structure by supplying calcium ions without generating carbon dioxide, while also ensuring the initial shape stability of the molded body.

[0009] In addition, technology for precisely controlling initial structural characteristics to ensure smooth diffusion and binding of mycelia under external culture conditions is also becoming increasingly important. In this context, there is a demand for new manufacturing technology for mycelial composite materials that simultaneously satisfy molding stability and shape precision. Prior art literature

[0010] Republic of Korea Registered Patent KR No. 10-2715754 Republic of Korea Registered Patent KR No. 10-2696191 U.S. Registered Patent US No. 9879219 The problem to be solved

[0011] To solve such problems, the present invention aims to provide a method for manufacturing a mycelial composite material that solves the conventional problem of a molded body expanding or deforming due to carbon dioxide generated by acidification during the internal gelation process, and can secure a stable shape and a uniform initial gel structure immediately after molding even without performing internal culture.

[0012] In addition, the present invention applies a hardening initiator having a dissolution and ion release mechanism different from that of calcium carbonate to fundamentally block the generation of carbon dioxide during the internal gelation process, and Ca 2+ By controlling the release rate, a uniform internal gel network is formed without bubble generation.

[0013] Furthermore, by controlling this gel structure, an initial structure is provided that allows the hyphae to stably penetrate and bind with only external culture, thereby enabling the implementation of a method for manufacturing a mycelial composite material that secures the desired shape and mechanical strength while omitting the internal culture process. means of solving the problem

[0014] To solve the above problems, the present invention comprises the steps of: (a) preparing a first solution by mixing a culture medium inoculated with bacteria, distilled water, and a curing agent; (b) preparing a second solution containing a curing initiator; (c) mixing the first solution, the second solution, and a curing accelerator; (d) forming a molded body using the mixture obtained in step (c); (e) externally culturing the molded body; and (f) drying the externally cultured molded body, wherein the curing initiator dissolves in acid without generating carbon dioxide and Ca 2+ A method for manufacturing a mycelial composite material is provided, characterized by being a non-carbonate calcium salt that releases [a substance].

[0015] The above curing agent may be sodium alginate.

[0016] It is preferable that the above-mentioned culture medium be ground using a sieve of 3 to 20 mm.

[0017] It is preferable that the moisture content of the first solution is 55 to 85 weight%.

[0018] The above-mentioned curing initiator may be tricalcium phosphate (TCP) or calcium edetate (Ca-EDTA).

[0019] The above curing accelerator may be a delayed hydrolysis type acid precursor.

[0020] The above delayed hydrolysis type acid precursor may be one or more selected from the group consisting of glucono-delta-lactone (GDL, glucono-δ-lactone), glucono-gamma-lactone (glucono-γ-lactone), ethyl citrate, triethyl citrate, glyceryl citrate, citrate buffer, phosphate buffer, and lactate buffer.

[0021] The above-mentioned curing accelerator may be in a form dissolved in water or a non-aqueous plasticizer.

[0022] The above-mentioned non-aqueous plasticizer may be one or more selected from the group consisting of polyethylene glycol (PEG-400), glycerol, propylene glycol, dipropylene glycol, diglycol, triethyl citrate, acetyl tributyl citrate, or glyceryl triacetate (triacetin).

[0023] Preferably, the mixture of step (c) comprises 90 to 98 weight% of the first solution, 1 to 6 weight% of the second solution, and 0.2 to 2.5 weight% of the curing accelerator.

[0024] A curing retardant may be optionally added during the mixing of step (c) above.

[0025] The above-mentioned curing retardant may be one or more selected from the group consisting of citrate, phosphate, lactate, gluconate, maleate, succinate, malate, tartrate, acetate, and formate.

[0026] The above step (d) is preferably performed for 5 to 180 seconds.

[0027] It is preferable that the above-mentioned molded body has a moisture content of 85 weight% or less when external cultivation is initiated.

[0028] It is preferable that the external culture of step (e) above be carried out at 20 to 35°C for 2 to 4 days.

[0029] It is preferable that the above drying be carried out at 35 to 65°C for 1 to 3 days. Effects of the invention

[0030] In the mycelial composite material of the present invention, by applying a non-carbonate calcium salt having dissolution and ion-releasing characteristics different from calcium carbonate as a curing initiator, carbon dioxide is not generated during the internal gelation process, thereby fundamentally suppressing the expansion of the molded body or the formation of bubbles. Accordingly, shape stability immediately after molding is greatly improved, and there is an effect of maintaining the desired shape without deformation, even in products requiring complex shapes or dimensional precision.

[0031] In addition, Ca by delayed hydrolysis type acid precursors 2+ As the gel is gradually released, a uniform gel network is formed throughout the interior, which reduces structural collapse during the external culture process and allows the hyphae to stably penetrate and bind within the molded body. This uniform initial structure enables uniform growth and strength development during the external culture stage, thereby improving the quality of the final mycelial material.

[0032] Furthermore, since sufficient initial strength and shape can be secured during the molding stage, there is no need to perform an internal culture process. Consequently, the overall manufacturing period is shortened and the mold turnover rate is increased, thereby significantly improving productivity. These advantages provide scalability that allows for stable application to products of various shapes and sizes. Brief explanation of the drawing

[0033] Figure 1 is a graph of the rate of change of pH of an aqueous GDL solution and a mixture of sodium alginate, Ca-EDTA, and GDL. Figure 2 is a graph of the compression-stress-strain curves of specimens prepared using the internal gelation method and the external gelation method. Figure 3 is a photograph showing the microstructure of a molded body manufactured by an internal gelation method. Figure 4 is a photograph showing the microstructure of a molded body manufactured by an external gelation method. Specific details for implementing the invention

[0034] Hereinafter, embodiments will be described in detail with reference to the attached drawings. The embodiments described in this specification and the configurations illustrated in the drawings are preferred embodiments of the present invention and do not represent all technical aspects of the present invention; therefore, various equivalents and modifications that can replace them may exist at the time of filing this application.

[0035] The terms used in the embodiments are for illustrative purposes only and should not be interpreted as intended to limit the scope of the invention. Singular expressions include plural expressions unless the context clearly indicates otherwise. In this specification, terms such as "comprising" or "having" are intended to indicate the existence of the features, numbers, steps, actions, components, parts, or combinations thereof described in the specification, and should be understood as not precluding the existence or addition of one or more other features, numbers, steps, actions, components, parts, or combinations thereof.

[0036] Unless otherwise defined, all terms used herein, including technical or scientific terms, have the same meaning as generally understood by those skilled in the art to which the embodiments pertain. Terms such as those defined in commonly used dictionaries should be interpreted as having a meaning consistent with their meaning in the context of the relevant technology, and should not be interpreted in an ideal or overly formal sense unless explicitly defined in this application.

[0037] Components that share common functions with components included in any one embodiment shall be described using the same names in other embodiments. Unless otherwise stated, the descriptions given in any one embodiment may also apply to other embodiments, and detailed descriptions shall be omitted to the extent of overlap.

[0039] The present invention relates to an internal gelation method for manufacturing a mycelium-based composite material. Specifically, to solve the problem of calcium carbonate (CaCO3)-based methods in which carbon dioxide is generated during the gelation process, causing the molded body to expand or deform, a non-carbonate calcium salt is used as a curing initiator, and a delayed-hydrolysis type acid precursor or buffer system is used to Ca 2+ A new manufacturing method is provided that induces internal gelation by controlling the release of over time.

[0040] The internal gelation method according to the present invention involves Ca required for gel formation. 2+ It is designed to be slowly released within the composition, so that a uniform gel network can be formed while maintaining shape stability immediately after molding, and a stable mycelial composite material can be manufactured in a short time without an internal culture process.

[0042] The method for manufacturing an internally gelling mycelial composite material of the present invention comprises the steps of: (a) preparing a first solution by mixing a culture medium inoculated with fungi, distilled water, and a curing agent; (b) preparing a second solution containing a curing initiator; (c) mixing the first solution, the second solution, and a curing accelerator; (d) forming a molded body using the mixture obtained in step (c); (e) externally culturing the molded body; and (f) drying the externally cultured molded body. Each process will be described in detail below.

[0044] First, (a) a first solution is prepared by mixing a culture medium inoculated with bacteria, distilled water, and a hardening agent.

[0045] The first solution consists of a culture medium inoculated with bacteria, a hardening agent, and distilled water. The culture medium is used after being ground to a particle size of 3 to 20 mm, preferably 3 to 15 mm. After measuring the moisture content of the culture medium after grinding it to the above range, the amount of distilled water to be added is calculated by applying it to the following formula 1 according to the target moisture content.

[0046] [Formula 1]

[0047]

[0048] (X: Total weight of medium, α: Current moisture content, β: Target moisture content)

[0049] After grinding, the moisture content of the medium is approximately 45 to 55% on average, and the target moisture content can be set to 55 to 75% considering the flowability of the first solution, the growth potential of mycelia, and physical properties after hardening. The preparation of the medium to be mixed with the first solution is completed by replenishing the moisture with distilled water and mixing.

[0050] The culture medium that can be used in the present invention may include one or more selected from the group consisting of wood-based by-products such as sawdust, wood chips, and wood flour, as well as grain by-products such as rice bran, wheat bran, rice husk, corn cobs, barley straw, and rice straw, or fibrous organic materials such as peanut shells, bean hulls, coconut coir, crushed bamboo, and bagasse.

[0051] The mycelium that can be used in the present invention is not limited to a specific strain, and, for example, strains of wood-rotting fungi or white-rotting fungi such as Pleurotus ostreatus, Ganoderma lucidum, Vanderbylia fraxinea, Trametes versicolor, Lentinula edodes, Schizophyllum commune, and Phanerochaete chrysosporium may be used.

[0052] All of the above strains grow actively in a lignocellulose-based medium and can diffuse three-dimensionally along the medium and internal gel network, making them suitable for manufacturing the mycelial composite material of the present invention. However, the present invention is not limited to the above strains, and other mycelia having similar growth characteristics may also be applied.

[0053] The amount of bacterial inoculum to the medium may vary depending on the type of medium, moisture content, culture environment, and the growth characteristics of the strain, but typically, an inoculum of about 10 g to 50 g per 1 kg of medium is used. However, if a sterile condition is stably maintained, theoretically, even if only a very small amount (e.g., 0.1 g) is added, there is no problem with the spread and cultivation of the bacteria, so the amount of inoculum is not limited to a specific value.

[0054] The optimal conditions for the culture process after inoculation vary depending on the strain used, but it is generally carried out at a temperature of approximately 25°C. During the culture process, the mycelium releases heat through metabolic activity, which can cause the internal temperature of the medium to rise above the ambient temperature; therefore, it is desirable to set the external temperature about 1 to 3°C lower than the optimal growth temperature of the mycelium.

[0055] In addition, to prevent the formation of fruiting bodies (mushrooms) during cultivation, it is common practice to maintain the carbon dioxide concentration at a level of about 4,000 to 8,000 ppm, and to suppress moisture loss in the medium, it is desirable to maintain the relative humidity at 60% or higher. Under these environmental conditions, the medium is cultured for about 10 to 30 days, during which time the mycelium penetrates and spreads throughout the medium to form a uniform network structure.

[0056] The curing agent is preferably sodium alginate, and it is preferable to add 0.02 to 0.04 times the weight of the ground medium. In addition, sodium alginate dissolves in distilled water and imparts viscosity and carboxyl groups throughout the medium, thereby causing subsequent Ca 2+ It provides a state capable of forming a gel network through a cross-linking reaction with. At this time, it is preferable that the amount of distilled water mixed with sodium alginate is 1.0 to 1.5 times the weight of the ground medium.

[0057] If the amount of curing agent is less than the above range, Ca 2+ As the binding ratio with becomes unbalanced, localized gelation occurs or an uneven network is formed, tending to reduce strength and impact resistance, and if the amount of curing agent exceeds the above range, COO - -Ca 2+ The crosslinking ratio is not saturated and non-crosslinked chains remain, causing an abnormal increase in the viscosity of the mixture due to increased residual viscosity and adhesiveness within the gel, resulting in problems such as reduced filling capacity and incomplete filling in the mold during the molding process.

[0058] The final moisture content of the first solution is suitable in the range of 55 to 85 weight%. If the moisture content is less than 55 weight%, the medium dries out, and the water activity required for mycelial growth is not secured. Additionally, there is a problem where nutrient diffusion and enzyme activity are reduced, and mycelial growth does not occur substantially. Furthermore, due to the lack of moisture, the processability of the mixture is significantly reduced, making it difficult to achieve uniform filling during molding and causing cracks, which reduces molding stability.

[0059] If the moisture content exceeds 85 weight%, the presence of excessive free water intensifies the hydration phenomenon, resulting in an uneven internal structure of the molded body, excessive shrinkage and deformation during the drying process, and an increased possibility of microbial contamination, which leads to a decrease in quality safety. Therefore, a final moisture content of 55 to 85 weight% can be considered a condition that simultaneously satisfies moldability and the mycelial growth environment.

[0061] In addition, plasticizers, foaming agents, fillers, etc. may be added selectively to express specific functions as needed, but they are not essential components of the internal gelation mechanism.

[0062] Plasticizers play a role in alleviating interactions between polymer chains to impart flexibility and deformability to the mixture, and improving fillability and processability during the molding process. Foaming agents generate bubbles within the molded body to provide lightweight and thermal insulation properties, and can be used to control density or secure shock absorption characteristics.

[0063] Foaming agents contribute to ensuring the stability and uniformity of the bubble structure by suppressing the collapse of bubbles formed during the foaming process. Fillers improve the mechanical strength, volumetric stability, and dimensional stability of the molded body, and may be added to reduce costs or control density in some cases. Antimicrobial additives may be used to maintain the stability of the mycelial growth environment by suppressing contamination and proliferation of unwanted microorganisms, and to prevent product quality degradation during storage and drying processes.

[0065] Next, (b) a second solution containing a curing initiator is prepared.

[0066] The curing initiator included in the second solution is Ca necessary for internal gelation. 2+ It is preferable that the calcium salt be a non-carbonate type that is slowly released within the composition, and tricalcium phosphate (TCP) or calcium edetate (Ca-EDTA) are representative examples.

[0067] When TCP is used, since TCP exhibits extremely low solubility in the neutral pH range of 6 to 8, most of it exists in the second solution in the form of solid fine particles and is dispersed in a uniformly suspended state within the solution. Due to these low solubility characteristics, during the initial mixing step, Ca 2+ The release of [the substance] is effectively suppressed, and accordingly, early crosslinking of sodium alginate does not occur, so the flowability of the composition is maintained stably.

[0068] Subsequently, as the pH of the composition gradually decreases due to the action of delayed hydrolysis-type acid precursors (such as GDL), fine dissolution begins from the surface of the TCP particles, and as a result, Ca 2+ and PO4 3- The onion is gradually released in a time-dependent manner.

[0069] Ca released in this way 2+ It selectively binds to the carboxyl groups of curing agents such as sodium alginate to promote internal gelation, which forms a uniform crosslinking network throughout the composition and plays a role in improving the structural stability and mechanical strength of the final molded body.

[0070] The amount of TCP added is n, the total number of moles of carboxyl groups in sodium alginate. coo- It can be set based on, and theoretically 0.4 to 0.8 mol of Ca per 1 mol of carboxyl group 2+A range capable of supplying is desirable. This is theoretically 2.0 to 4.0 mmol of Ca per 1 g of sodium alginate. 2+ It corresponds to the amount of TCP added that can provide.

[0071] When using Ca-EDTA, Ca-EDTA is strongly chelated Ca when dissolved in water. 2+ It contains, and under neutral conditions of pH 6 to 8, Ca 2+ Almost no is released. However, as the pH of the solution gradually decreases due to the hydrolysis of delayed-hydrolysis acid precursors, EDTA is gradually protonated, and Ca 2+ The binding force weakens and Ca 2+ It dissociates in stages.

[0072] In the neutral range (pH 6 to 8), Ca 2+ Release hardly occurs until the pH decreases to about 5 or below, at which point Ca 2+ The release rate accelerates, and at pH around 4.5, Ca 2+ The release rate reaches its maximum. When the pH drops to near 3.5, Ca-EDTA almost completely dissociates, and the bound Ca 2+ Practically 100% is released. As such, in the Ca-EDTA-based method, the decomposition rate of the delayed-hydrolysis acid precursor is directly related to Ca 2+ It becomes a key factor in determining the release rate and internal gelation rate.

[0073] The amount of Ca-EDTA added can also be set based on the total moles of carboxyl groups of sodium alginate, and theoretically 3 to 10 mmol of Ca per 1 g of sodium alginate 2+ A range capable of supplying is desirable.

[0075] Next, (c) the first solution, the second solution, and the curing accelerator are mixed.

[0076] The mixing of the first solution and the second solution is performed such that, based on the total composition, the first solution is 90 to 98 weight%, the second solution is 1 to 6 weight%, and the curing accelerator is 0.2 to 2.5 weight%. The curing accelerator has a composition including a delayed hydrolysis type acid precursor or a buffer solution, and is added simultaneously at the time the mixing of the first solution and the second solution begins so that the three components are uniformly dispersed.

[0077] Delayed-hydrolysis acid precursors are substances that react with water to slowly produce acid over a certain period of time; examples include lactones such as glucono-delta-lactone (GDL) and glucono-gamma-lactone, or organic acid esters such as ethyl citrate, triethyl citrate, and glyceryl citrate. Since these substances can control the rate of pH decrease depending on the hydrolysis rate, Ca 2+ It is suitable for temporally controlling the release rate and the progression of internal gelation.

[0078] Other types of curing accelerators include citrate buffer, phosphate buffer, and lactate buffer; these buffers initially suppress pH changes to prevent rapid gelation, and after the buffering capacity is exhausted, they act to cause the pH to decrease gradually. Due to these characteristics, moldability is maintained immediately after mixing, and in subsequent stages, Ca 2+ A two-stage internal gelation is implemented in which release and cross-linking reactions proceed.

[0079] The curing accelerator may be used in a form dissolved in water or a non-aqueous plasticizer depending on the formulation (liquid or solid), solubility, and dissociation rate of the curing initiator. The non-aqueous plasticizer may include polyethylene glycol (PEG-400), glycerol, propylene glycol, dipropylene glycol, diglycol, triethyl citrate, acetyl tributyl citrate, or glyceryl triacetate (triacetin), and may play a role in improving the flexibility and processability of the molded article without inhibiting the internal gelation mechanism.

[0080] GDL has the characteristic of undergoing hydrolysis over time in an aqueous solution, but this implies limitations related to formulation stability during long-term storage. In a process that induces gelation immediately after mixing, as in the present invention, the hydrolysis of GDL is Ca 2+ It acts as a functional element contributing to release and pH control. Furthermore, since the hydrolysis rate is controlled by process variables such as GDL concentration, temperature, the buffering capacity of the medium, and diffusion resistance due to solids, it is possible to use water or distilled water as a solvent.

[0081] The composition immediately after mixing the first solution, the second solution, and the curing accelerator maintains a flowable paste state. At this point, the hydrolysis of the acid precursor has not progressed sufficiently, so the pH change is not significant, and Ca from non-carbonate calcium salts 2+ Since release is also limited, it is maintained in a moldable state before internal gelation begins in earnest.

[0083] Next, (d) a molded body is made using the mixture obtained in step (c) above.

[0084] Since the composition immediately after mixing is in a dough state before a complete gel structure is formed, it can be molded into a desired shape through processes such as injection, compression molding, pressing, and mold filling. Molding is preferably performed immediately after the first solution, the second solution, and the curing accelerator are uniformly mixed, and typically, the molding operation is carried out within 5 to 180 seconds after the mixing is completed.

[0085] If the pH gradually decreases over time due to the hydrolysis of the acid precursor or the depletion of the buffer capacity of the buffer solution after the molded body is formed, Ca from the curing initiator 2+ Release proceeds in earnest, and accordingly, internal gelation occurs throughout the interior of the molded body, forming a three-dimensional composite structure in which the gel network, culture medium, and mycelium are integrated.

[0086] Unlike external gelation, where a gel layer is formed from the surface by injecting a CaCl₂ solution from the outside, this internal gelation method, Ca 2+ Since it proceeds uniformly throughout the entire molded body without a concentration gradient, a gel network with a uniform structure can be formed even inside the molded body.

[0087] In particular, since the present invention uses a non-carbonate calcium salt instead of a carbonate calcium salt that generates carbon dioxide under acidic conditions, such as calcium carbonate, carbon dioxide bubbles are not formed during the gelation process, so the expansion or shape deformation of the molded body is suppressed, and dimensional stability can be secured even in molded bodies with complex shapes.

[0089] Afterwards, (e) the molded body that has been molded is cultured externally.

[0090] After the molding is completed, the molded body is separated from the mold and cultured externally. When external culture is initiated, it is preferable that the moisture content of the molded body be 85% by weight or less. If the moisture content is excessively high, structural collapse of the molded body may occur during the external culture process, and conversely, if it is too low, the growth and diffusion of mycelia may be inhibited.

[0091] External culture is typically performed for 2 to 4 days at a temperature of 20 to 35°C, during which time the mycelium forms a uniform mycelial network by penetrating and binding throughout the molded body along the internal gel network, the medium, and optionally included pulp fibers. The uniform pore structure and initial strength already formed during the internal gelation stage suppress structural collapse that may occur during external culture, and allow the mycelium to rapidly spread and establish itself in three dimensions.

[0093] Finally, (f) the above externally cultured molded body is dried.

[0094] Drying can be performed by maintaining the molded body at a temperature range of 35 to 65°C for 1 to 3 days, and various methods such as natural drying, hot air drying, or drying using a constant temperature and humidity chamber may be used. The completion of drying can be determined based on the weight of the molded body, and the drying completion point can be determined when the weight measured at regular time intervals no longer decreases. In addition, the completion of drying can also be determined when the residual moisture content of the molded body is measured using moisture measuring equipment such as an infrared moisture analyzer and becomes 8 to 10% or less, which is a preset value.

[0095] The dried molded body is a final mycelial composite material in which an internal gel network, mycelium, culture medium, and optional additives are integrated, and it is characterized by having excellent shape stability, mechanical strength, and a uniform structure without requiring a separate internal culture period.

[0097] The present invention will be described in more detail below through examples and test examples. These examples and test examples are solely for the purpose of more specifically explaining the present invention, and it is obvious to those skilled in the art that the scope of the present invention is not limited by these examples and test examples according to the gist of the present invention.

[0099] <Example>

[0100] Example 1: Preparation of an internally gelling mycelial composite material using TCP

[0101] First, the first solution was prepared by mixing 30 g of sawdust medium, 1.1 g of sodium alginate, and 45 mL of distilled water. The mixture was stirred to ensure that the sodium alginate was uniformly dissolved and dispersed.

[0102] Next, the second solution was prepared by adding 0.8 g of tricalcium phosphate (TCP, Ca₃(PO₄)₂) to 2 mL of distilled water. Since TCP exhibits extremely low solubility under neutral pH conditions, it exists as a fine suspension in the second solution, and in the subsequent step, Ca₃ is generated by acid formation 2+ We prepared so that it could be released.

[0103] Subsequently, during the process of mixing the first and second solutions, 0.7 g of glucono-delta-lactone (GDL) was added separately. Immediately after mixing, GDL reacts with moisture to gradually exhibit acidity, and accordingly, the pH of the composition slowly decreases over time. As the pH decreases, the TCP surface is partially dissolved, and the released Ca 2+ It reacts with the carboxyl groups of sodium alginate to form a cross-linked structure.

[0104] Immediately after mixing, the mixture was in a flowable paste state, and gradual gelation proceeded within about 3 minutes depending on the hydrolysis rate of GDL. Once gelation was complete, a uniform three-dimensional cross-linked structure containing sawdust medium was formed, and a hardened mycelial composite material was finally obtained through a 3-day external culture and 2-day drying process after molding.

[0106] Example 2: Preparation of an internally gelling mycelial composite material using Ca-EDTA

[0107] First, a first solution was prepared by mixing 30 g of sawdust medium, 1.1 g of sodium alginate, and 45 mL of distilled water. The mixture was stirred to ensure that the sodium alginate was uniformly dissolved and dispersed.

[0108] Next, the second solution was prepared by dissolving 1.0 g of calcium edetate (Ca-EDTA) in 2 mL of distilled water. Ca-EDTA is prepared under neutral conditions (pH 6–8) by Ca 2+ Since it exists in a stable chelate state with almost no release, Ca in the subsequent acid generation process 2+ It becomes ready to be dissociated in stages.

[0109] Subsequently, 0.8 g of GDL (glucono-δ-lactone) was added separately during the process of mixing the first and second solutions. After mixing, GDL reacts with moisture and gradually exhibits acidity over time, causing the pH of the composition to gradually decrease. Ca-EDTA [causes] Ca at a pH of approximately 5 or lower. 2+ Dissociation begins in earnest, and at pH around 4.5, Ca 2+ The release rate reaches its maximum, and when the pH approaches approximately 3.5, Ca 2+ It is known that it is almost completely dissociated. Therefore, in this embodiment, by controlling the hydrolysis rate of GDL, Ca 2+ The release rate and internal gelation rate can be precisely controlled.

[0110] Immediately after mixing, the mixture was in the form of a viscous paste, and gelation gradually proceeded within minutes depending on the hydrolysis rate of GDL. After gelation was complete, the Ca-EDTA-based Ca 2+ A uniform alginate-calcium cross-linked structure formed by release was maintained, and a finally hardened mycelial composite material was obtained through 3 days of external culture and 2 days of drying process after molding.

[0111] The compositional ratio of Ca-EDTA and GDL used in this example is Ca per 1 g of sodium alginate 2+ It is set to add an amount of Ca-EDTA capable of supplying 3 to 10 mmol, wherein 3 to 10 mmol of Ca per 1 g of sodium alginate2+ It was set so that an amount of Ca-EDTA capable of supplying was added. In this example, 1.0 g of Ca-EDTA was used for every 1.1 g of sodium alginate.

[0112] The above composition ratio is Ca relative to 1 mol of carboxyl group of sodium alginate. 2+ It was designed so that the release amount was about 0.3 to 0.6 mol, which was advantageous for ensuring the gelation rate and uniformity of the cross-linked structure.

[0114] <Comparative Example>

[0115] Comparative Example 1: Preparation of a mycelial composite material by an external gelation method

[0116] To verify the performance difference with the example applying the internal gelation method, the same culture medium composition and curing agent composition were used, but Ca 2+ A specimen was prepared by applying an external gelation method that supplies from the outside.

[0117] First, a first mixture was prepared by mixing 30 g of sawdust medium, 1.1 g of sodium alginate, and 45 mL of distilled water. The mixture was stirred to ensure that the sodium alginate was uniformly dissolved and dispersed throughout the medium. The medium, moisture content, and amount of sodium alginate added used at this time were the same as those in Example 1.

[0118] Subsequently, the above-mentioned first mixture was filled into a mold to produce a molded body. Immediately after molding, the molded body remained in a fluid dough state in which internal gelation had not occurred; in this state, the molded body was immersed in a 1.0 M aqueous calcium chloride (CaCl₂) solution to initiate external gelation. The immersion time was set to 5 minutes. Ca 2+ It diffused from the outer surface of the molded body during the immersion process, and local crosslinking reactions proceeded rapidly in the outer layer.

[0119] Due to the characteristics of the external gelation method, Ca 2+The diffusion behavior is restricted to the direction from the outside to the inside of the molded body, and sufficient Ca reaches the center of the molded body during the immersion time. 2+ It did not reach. As a result, a relatively hard gel layer was formed on the outer layer of the molded body, but the center remained in an uncrosslinked or partially crosslinked state, causing structural non-uniformity.

[0120] After the immersion process was completed, the molded body was removed from the CaCl2 solution to remove moisture, and then the same external culture and drying processes were performed. External culture was carried out at 25°C for 3 days, and then dried at 45°C for 2 days to obtain an external gelation-based mycelial composite material.

[0122] <Test Example>

[0123] Test Example 1: Analysis of pH change behavior in internal gelation method

[0124] Prior to pH measurement, the pH meter was calibrated at two points using pH 4.00 and pH 7.00 buffer solutions at 25°C, identical to the experimental conditions. After calibration, the electrode was washed with distilled water, lightly dried with filter paper, and then used.

[0125] The preparation of the GDL aqueous solution in Fig. 1(a) is as follows. 2.0 g of GDL was placed in a 100 mL capacity beaker, and 80 mL of distilled water was added and stirred at 300 rpm on a magnetic stirrer to completely dissolve it. Subsequently, distilled water was added up to the mark to prepare a final 100 mL, i.e., 2 wt / volume% (w / v) GDL aqueous solution. A pH electrode was immersed in the solution to record the first measurement value, and the pH was subsequently measured at 2-minute intervals for the first 10 minutes and at 10-minute intervals up to 90 minutes. During the measurement, the top of the beaker was partially sealed with Parafilm to minimize evaporation and the influx of external CO2.

[0126] The sodium alginate-Ca-EDTA-GDL mixture system of Fig. 1(b) was prepared as follows. 2.0 g of sodium alginate was slowly added to 100 mL of distilled water and stirred sufficiently at 1,000 rpm at 25°C to completely dissolve it. Ca-EDTA was dissolved in distilled water according to the calculated amount, and then water was added to the final volume to prepare a 0.1 M aqueous solution. Subsequently, the 2 wt% sodium alginate aqueous solution and the 0.1 M Ca-EDTA aqueous solution were mixed in a volume ratio of 30:1 and stirred at 1,000 rpm to obtain a homogeneous mixture. Afterward, 2.0 g of GDL was added to achieve a final concentration of 2% of GDL in the mixed solution, and this point was defined as t = 0 min. pH was measured immediately after the addition of GDL, with measurement intervals set to 2-minute intervals for the first 10 minutes and 10-minute intervals thereafter until 90 minutes. At this time, the top of the beaker was also partially sealed with Parafilm to suppress the inflow and evaporation of external CO2.

[0127] As a result of the measurement, the aqueous solution of GDL alone in Fig. 1(a) showed a rapid decrease in pH within minutes of the reaction initiation from an initial pH of about 3.3, and the pH decreased to about 2.6 after about 80 minutes. This means that acid production due to the hydrolysis of GDL proceeds rapidly.

[0128] The mixed system in Fig. 1(b) exhibited a relatively gradual rate of pH decrease, starting at an initial pH of approximately 5.9 and gradually falling to a pH of approximately 4.5 after 80 minutes. This is because Ca-EDTA interacts with the carboxyl groups of alginate and the hydrolysis products of GDL to delay initial acidification, while the stepwise protonation process of EDTA regulates the rate of pH change. This pH change behavior is due to Ca 2+ It also affects the dissociation and diffusion rates of, so the mixed system (b) has more gradual Ca compared to the single system (a). 2+It was confirmed to form a release environment.

[0130] Test Example 2: Comparison of Compression Characteristics Between Internal Gelation and External Gelation Methods

[0131] Compressive strength evaluation was performed using the same Universal Testing Machine (UTM) in a standard environment at 25°C and 50% relative humidity. Specimens were fabricated in a rectangular shape; prior to testing, their dimensions were measured according to specifications, and they were aligned and positioned in the center of the jig with the flat surface perpendicular to the direction of load application. For the compression test, load-displacement data was acquired in real-time while continuously applying a uniaxial load at a crosshead speed of 10 mm / min to calculate the stress-strain curve. Compressive strength was determined based on the point at which the maximum stress appeared on the stress-strain curve, and the average value was calculated by repeating measurements at least three times for each condition.

[0132] In Test Example 2, compression characteristics were compared using the internal gelation specimen prepared in Example 1 and the external gelation specimen prepared in Comparative Example 1. The compression behavior of the two specimens is as shown in Fig. 2.

[0133] In the case of external gelling specimens, Ca 2+ As the ion diffused rapidly from the outer surface of the specimen, localized bridges formed first in the outer layer, and sufficient ion exchange did not occur in the interior. Consequently, although similar deformation behavior was observed during the initial load increase range, structural collapse occurred before reaching the limiting strain or set limiting stress, resulting in low compressive strength and strength uniformity.

[0134] On the other hand, specimens prepared by the internal gelation method contained Ca throughout the interior of the molded body. 2+It was gradually released over time, and accordingly, an alginate-based cross-linked structure was uniformly formed from the center to the outer edge. Due to this structural formation behavior, the internally gelled specimen exhibited a stable stress-strain curve throughout the test range, and stress continued to increase without structural collapse even in the high-strain region, demonstrating higher compressive strength and excellent strength uniformity compared to the externally gelled specimen.

[0135] In addition, the results of observing the microstructure of specimens prepared by the two methods are shown in Figs. 3 and 4. In the internally gelled specimen of Fig. 3, a continuous and uniform gel network was observed throughout the entire molded body, which is Ca 2+ This is the result of global crosslinking proceeding as it diffuses within the composition. On the other hand, the external gelled specimen in Fig. 4 is Ca 2+ Structural non-uniformity was confirmed as it rapidly diffused from the outer surface, forming selective crosslinking only in the outer layer, while uncrosslinked regions remained in the interior. These microstructural differences serve as the basis for explaining the differences in compressive strength and strength uniformity observed in Figure 2.

Claims

Claim 1 A method for manufacturing a mycelial composite material comprising: (a) a step of preparing a first solution by mixing a culture medium inoculated with fungi, distilled water, and a curing agent; (b) a step of preparing a second solution containing a curing initiator; (c) a step of mixing the first solution, the second solution, and a curing accelerator; (d) a step of making a molded body using the mixture obtained in step (c); (e) a step of externally culturing the molded body; and (f) a step of drying the externally cultured molded body, wherein the curing agent comprises sodium alginate and the curing initiator is tricalcium phosphate (TCP) or calcium edetate (Ca-EDTA). Claim 2 delete Claim 3 A method for manufacturing a mycelial composite material according to claim 1, characterized in that, in step (a), the culture medium is crushed using a sieve of 3 to 20 mm. Claim 4 A method for manufacturing a mycelial composite material according to claim 1, characterized in that, in step (a), the moisture content of the first solution is 55 to 85 weight%. Claim 5 delete Claim 6 A method for manufacturing a mycelial composite material according to claim 1, wherein in step (c), the curing accelerator is a delayed hydrolysis type acid precursor or a buffer solution. Claim 7 A method for manufacturing a mycelial composite material according to claim 6, wherein the delayed hydrolysis type acid precursor and the buffer are one or more selected from the group consisting of glucono-delta-lactone (GDL), glucono-gamma-lactone (glucono-γ-lactone), ethyl citrate, triethyl citrate, glyceryl citrate, citrate buffer, phosphate buffer, and lactate buffer. Claim 8 A method for manufacturing a mycelial composite material according to claim 1, wherein in step (c), the curing accelerator is in a form dissolved in water or a non-aqueous plasticizer. Claim 9 A method for manufacturing a mycelial composite material according to claim 8, wherein the non-aqueous plasticizer is one or more selected from the group consisting of polyethylene glycol (PEG-400), glycerol, propylene glycol, dipropylene glycol, diglycol, triethyl citrate, acetyl tributyl citrate, or glyceryl triacetate (triacetin). Claim 10 A method for manufacturing a mycelial composite material according to claim 1, wherein in step (c), the mixture comprises 90 to 98 weight% of the first solution, 1 to 6 weight% of the second solution, and 0.2 to 2.5 weight% of the curing accelerator. Claim 11 A method for manufacturing a mycelial composite material according to claim 1, characterized in that a curing retardant may be optionally further included during the mixing of step (c). Claim 12 A method for manufacturing a mycelial composite material according to claim 11, wherein the hardening retardant is one or more selected from the group consisting of citrate, phosphate, lactate, gluconate, maleate, succinate, malate, tartrate, acetate, and formate. Claim 13 A method for manufacturing a mycelial composite material according to claim 1, wherein step (d) is performed for 5 to 180 seconds. Claim 14 A method for manufacturing a mycelial composite material according to claim 1, wherein in step (e), the molded body has a moisture content of 85 weight% or less when external cultivation is initiated. Claim 15 A method for manufacturing a mycelial composite material according to claim 1, wherein in step (e), the external culture is carried out at 20 to 35°C for 2 to 4 days. Claim 16 A method for manufacturing a mycelial composite material according to claim 1, wherein in step (f), the drying is carried out at 35 to 65°C for 1 to 3 days. Claim 17 A mycelial composite material manufactured by the manufacturing method of any one of paragraphs 1, 3, 4 and 6 through 16.

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