A method for preparing high-value sugarcane bagasse dietary fiber raw materials by using pachyman semi-solid fermentation

Abstract

This invention discloses a method for preparing high-value-added sugarcane bagasse dietary fiber raw materials using Poria cocos semi-solid fermentation. The method includes: drying and pulverizing sugarcane bagasse, sterilizing it, cooling it, inoculating it with Poria cocos for semi-solid fermentation, stirring it periodically during fermentation, and drying, pulverizing, and sieving the raw materials after fermentation to obtain the dietary fiber raw materials. This invention also provides a preferred scheme for fermentation using a compound Poria cocos strain. This invention significantly increases the soluble dietary fiber content in sugarcane bagasse through a specific fermentation process, while promoting the accumulation of antioxidant functional components such as polysaccharides, total phenols, and total flavonoids. The fermentation cycle is fixed and controllable, the process is green and environmentally friendly, requiring no expensive chemical reagents or enzyme preparations, and the product can be directly used as a functional food ingredient or dietary supplement, showing good prospects for industrial application.

Description

Technical Field

[0001] This invention relates to the field of agricultural product processing and food ingredient technology, specifically to a method for preparing high-value-added sugarcane bagasse dietary fiber raw materials using Poria cocos semi-solid fermentation. Background Technology

[0002] Sugarcane bagasse is a major solid byproduct of sugarcane refining. As a major sugarcane-growing country, my country generates a large amount of sugarcane bagasse waste annually. Sugarcane bagasse is rich in dietary fiber, hemicellulose, polysaccharides, and a small amount of soluble sugars, making it a potential biomass resource. However, the dietary fiber in virgin sugarcane bagasse is primarily insoluble, with low levels of soluble fiber. Furthermore, the content of polysaccharides and natural antioxidants is limited. These characteristics restrict its direct application value in functional foods, dietary supplements, and health foods.

[0003] Currently, common methods for modifying dietary fiber in sugarcane bagasse include physical pulverization, chemical modification, and enzymatic hydrolysis. Physical pulverization mechanically destroys the fiber structure of bagasse, but this easily leads to the loss of dietary fiber and functional components, failing to efficiently increase the content of soluble dietary fiber, polysaccharides, and antioxidants. Chemical modification uses acids, alkalis, and other chemical reagents, which can destroy the fiber structure of bagasse, but suffers from high energy consumption, reagent residues, and environmental pollution. Enzymatic hydrolysis requires expensive enzyme preparations, has strict hydrolysis conditions, is complex to operate, and has high costs for industrial application, while also resulting in significant loss of nutrients and functional components.

[0004] In recent years, microbial fermentation methods have been increasingly applied to sugarcane bagasse modification research. Existing microbial fermentation methods mostly employ lactic acid bacteria or yeast for solid-state fermentation. However, these methods have limited ability to convert insoluble fiber in sugarcane bagasse into soluble dietary fiber and functional components, have uncertain fermentation cycles, and insufficient functional enhancement, making it difficult to establish a controllable industrial-scale process. In addition, some studies have reported using Bacillus subtilis to ferment sugarcane bagasse, achieving a soluble dietary fiber extraction rate of 17.95%. Other studies have reported the effects of Aspergillus niger solid-state fermentation on the release of polyphenols and flavonoids and antioxidant properties in sugarcane leaves. Still other studies have reported using Poria cocos to solid-state fermentate shiitake mushroom stem substrate, showing a significant increase in soluble dietary fiber content, a 97.75% increase in DPPH free radical scavenging rate, and a 38.15% increase in hydroxyl free radical scavenging rate. Although some studies have indicated that fermenting sugarcane bagasse with Poria cocos can increase soluble dietary fiber and antioxidant functional components, the specific fermentation process parameters (temperature, humidity, fermentation cycle, etc.) have not been disclosed. Therefore, there are no systematic reports on the use of Poria cocos to ferment sugarcane bagasse to specifically increase soluble dietary fiber and antioxidant functional components.

[0005] In summary, how to convert the insoluble dietary fiber in sugarcane bagasse into soluble dietary fiber in an economical, green, and efficient manner, while simultaneously enhancing polysaccharides and antioxidant functional components, and forming a controllable and industrially feasible fermentation process, is a technical problem that urgently needs to be solved. Summary of the Invention

[0006] To address the aforementioned technical problems in the existing technology, this invention provides a method for preparing high-value-added sugarcane bagasse dietary fiber raw materials using Poria cocos semi-solid fermentation. This invention selects Poria cocos as the fermentation strain and utilizes its naturally secreted fiber-degrading enzyme system to partially hydrolyze the insoluble dietary fiber in sugarcane bagasse into soluble dietary fiber. Simultaneously, the microbial metabolic activity promotes the accumulation of antioxidant components such as polysaccharides, flavonoids, and phenolic acids, thus achieving functional modification of the sugarcane bagasse dietary fiber.

[0007] To address the aforementioned technical problems, this invention, through in-depth research and process optimization, proposes the following technical solution: A method for preparing high-value-added sugarcane bagasse dietary fiber raw material using Poria cocos semi-solid fermentation includes the following steps: A. Raw material pretreatment: Dry sugarcane bagasse to a moisture content of 10% to 15%, and crush it to a particle size of 1 to 3 mm to obtain sugarcane bagasse powder; B. Sterilization treatment: Sterilize or treat the sugarcane bagasse powder obtained in step A at high temperature for a short time, and then cool it to 30-35°C. C. Inoculation and fermentation: Inoculate the cooled sugarcane bagasse powder with Poria cocos strain at a rate of 5% to 10% of the wet weight and mix thoroughly; the Poria cocos strain includes Poria cocos P5.78; D. Semi-solid fermentation: The inoculated material is transferred into a fermentation tank, the moisture content of the material is adjusted to 55% to 65%, the temperature is maintained at 28 to 32℃ and the humidity is 60% to 70%, and semi-solid fermentation is carried out. The fermentation cycle is 12 to 18 days. During the fermentation process, the material is turned over once every 2 to 3 days. The fermentation environment is kept stable by monitoring pH, temperature and humidity. E. Product processing: After fermentation, the fermented material is dried to a moisture content of 10% to 12%, crushed and sieved to obtain high-value-added sugarcane bagasse dietary fiber raw material.

[0008] In step A, drying the sugarcane bagasse to a moisture content of 10%–15% is beneficial for subsequent crushing and storage. If the moisture content is too high, it easily clumps during crushing and is detrimental to moisture control during subsequent sterilization and fermentation; if the moisture content is too low, dust will be generated excessively during crushing. Crushing to a particle size of 1–3 mm increases the specific surface area, which is beneficial for mycelial adhesion and nutrient utilization. Through extensive experiments, the inventors have found that excessively large particle sizes hinder the penetration of fermentation mycelia, while excessively small particle sizes may lead to excessively high material density, affecting aeration.

[0009] In step B, sterilization or short-time high-temperature treatment is used to kill contaminating bacteria in the raw materials, ensuring the pure fermentation of Poria cocos bacteria. The sterilized material needs to be cooled to 30–35°C to avoid damage to the bacterial activity caused by high temperatures.

[0010] In step C, the inoculum amount is controlled at 5%–10% of the wet weight, a result obtained by the inventors through extensive experimental optimization. If the inoculum amount is too low (<5%), fermentation starts slowly, mycelial growth is insufficient, and the fermentation cycle is prolonged; if the inoculum amount is too high (>10%), there will be too many microorganisms in the material, which may lead to excessive nutrient consumption in the early stage of fermentation, affecting the subsequent accumulation of functional components. The *Poria cocos* strain mentioned includes *Poria cocos* P5.78. *Poria cocos* P5.78 has advantages such as rapid mycelial growth and strong fiber degradation ability, and can efficiently complete the fiber conversion and functional component accumulation of sugarcane bagasse within a short fermentation cycle.

[0011] In step D, semi-solid fermentation is the core process step of this invention. Semi-solid fermentation falls between liquid and solid fermentation, with the material in a moist, loose state. It retains the energy-saving and easy-to-operate advantages of solid fermentation while offering better mass and heat transfer performance than pure solid fermentation. During their research, the inventors discovered that the moisture content of the material is a key factor affecting the semi-solid fermentation effect: when the moisture content is low (<55%), the mycelial growth of *Poria cocos* is slow, and the secretion of cellulose-degrading enzymes is insufficient; when the moisture content is high (>65%), the material's aeration deteriorates, oxygen supply is insufficient, and the aerobic metabolism of the microorganisms is affected. Therefore, the moisture content of the material is limited to 55%–65%, preferably 58%–62%.

[0012] The fermentation temperature of 28–32℃ and humidity of 60%–70% were determined based on the optimal growth temperature range (28–32℃) of *Poria cocos* and its solid-state fermentation characteristics. *Poria cocos* exhibits vigorous mycelial growth, active enzyme secretion, and the strongest fiber degradation and functional component accumulation capabilities within the 28–32℃ range. An ambient humidity of 60%–70% effectively prevents the material surface from drying out and maintains suitable moisture conditions in the microenvironment. During fermentation, the material is turned over every 2–3 days to improve aeration, ensure even oxygen distribution, and prevent uneven fermentation caused by localized overheating or excessive humidity. Monitoring pH, temperature, and humidity maintains the activity of the mycelium and the stability of the fermentation environment, preventing excessive acidity or high temperatures from affecting the fermentation results.

[0013] A fermentation cycle of 12-18 days is the optimal fermentation time determined by the inventors through extensive experiments. If the fermentation time is too short (<12 days), the Poria cocos fungus cannot grow and metabolize sufficiently, resulting in insufficient fiber degradation and accumulation of functional components; if the fermentation time is too long (>18 days), the mycelium ages, and the functional components may be further metabolized and consumed, and production efficiency decreases.

[0014] In step E, after fermentation is complete, the fermented bagasse is dried to a moisture content of 10%–12%, which effectively terminates the fermentation process and extends the product's shelf life. The final fermented product is obtained by crushing and sieving, and can be directly used as a functional food ingredient or dietary supplement.

[0015] As a further improvement of the present invention, the Poria cocos strain in step C is composed of Poria cocos P5.78 and Poria cocos Xiangjing 28, and the mass ratio of Poria cocos P5.78 to Poria cocos Xiangjing 28 is 1:0.4 to 1.3.

[0016] Based on single-strain fermentation, the inventors discovered that when a compound Poria cocos strain, formed by combining Poria cocos P5.78 and Poria cocos Xiangjing 28 in a certain ratio, is used for fermentation, the two strains exhibit a significant non-linear synergistic effect in sugarcane bagasse fiber degradation and functional component accumulation, with effects far superior to those of using each strain alone. The synergistic effect is most significant when the mass ratio of P5.78 to Xiangjing 28 is in the range of 1:0.4 to 1.3.

[0017] As will be understood by those skilled in the art, the *Poria cocos* strain P5.78 refers to the *Poria cocos* strain with the original number 5.78, a commercially available standard strain with the Latin name *Poria cocos*. It is cultured at 28-32℃ and is primarily used for medicinal and research purposes. This strain is readily available to the public through various commercial channels, such as Ningbo Mingzhou Biotechnology Co., Ltd. (product code B81979), Shanghai Huzheng Biotechnology Co., Ltd., Taisto Biotechnology (product code TS275378), and Shanghai Xuanya Biotechnology Co., Ltd., all of which have long-term stock availability of this strain. This strain exhibits rapid mycelial growth, quickly colonizing and forming a mycelial network in semi-solid fermentation systems. It efficiently secretes fiber-degrading enzymes, effectively degrading the fiber structure of sugarcane bagasse.

[0018] As those skilled in the art will understand, the aforementioned *Poria cocos* fungus, Xiangjing 28, was isolated, domesticated, and bred from wild *Poria cocos* collected by the Xiang-Gui-Qian Institute of Edible and Medicinal Fungi in Jingzhou County, Hunan Province in 2004. It was approved by Hunan Province in 2010 (approval number XPD007-2010). This variety has robust, white mycelia, distinct clamp connections, and early and uniform *poria cocos* formation. The public can directly purchase it online through the National Electronic Trade Platform for Poria cocos and its Products or through commercial channels such as the Jingzhou Miao and Dong Autonomous County Poria cocos Professional Cooperative.

[0019] As a further improvement of the present invention, the drying temperature in step A is 50–70°C, and the drying time is 6–12 hours. This temperature range is beneficial for efficiently removing moisture while preserving the nutritional components of the bagasse. The pulverization in step A is carried out using a mechanical pulverizer. Mechanical pulverizers (such as high-speed universal pulverizers) can efficiently pulverize the dried bagasse to the required particle size, are easy to operate, and are suitable for industrial production.

[0020] As a further improvement of the present invention, the sterilization process in step B is high-pressure steam sterilization, with a sterilization temperature of 120-122°C and a sterilization time of 15-30 minutes. These parameters effectively kill most microorganisms in the raw materials while avoiding excessive processing that could damage the nutritional components of the sugarcane bagasse. The 15-30 minute heat treatment time further ensures the sterilization effect.

[0021] As a further improvement of the present invention, the fermentation cycle in step D is 14 days; the moisture content of the material in the semi-solid fermentation in step D is 58%–62%. Extensive experiments have shown that the content of soluble dietary fiber and functional components reaches its peak after 14 days of fermentation, and thereafter no longer increases significantly with prolonged fermentation time. The mycelial growth state is optimal when the moisture content of the material is within the range of 58%–62%, and the activity level of the fiber-degrading enzyme system is highest.

[0022] As a further improvement of the present invention, hot air drying is used in step E at a temperature of 50–65°C for 8–14 hours. Low-temperature hot air drying helps protect the heat-sensitive active ingredients in the fermentation product. As a further improvement of the present invention, sieving in step E is performed using a 40–100 mesh sieve. Sieving ensures the uniformity of product particle size, facilitating subsequent processing and application.

[0023] This invention also provides a high-value-added sugarcane bagasse dietary fiber raw material prepared by the above-described method. This product is rich in soluble dietary fiber and natural antioxidants, has a high total dietary fiber content, and exhibits good processing performance and functional activity.

[0024] This invention also provides the application of the aforementioned high-value-added sugarcane bagasse dietary fiber raw material in the preparation of functional foods, dietary supplements, or antioxidant health products. This product can be directly used as an ingredient in functional foods or further processed into dietary supplement products, achieving high-value utilization of sugarcane bagasse byproducts.

[0025] Beneficial effects: Compared with the prior art, the beneficial effects of the present invention are: 1. This invention uses Poria cocos bacteria to carry out semi-solid fermentation of sugarcane bagasse. The natural fiber-degrading enzyme system of Poria cocos bacteria is used to partially hydrolyze insoluble dietary fiber into soluble dietary fiber. The soluble dietary fiber content can be significantly increased from about 5% before fermentation to more than 13%, which effectively solves the problem of low soluble dietary fiber content in sugarcane bagasse.

[0026] 2. While increasing the content of soluble dietary fiber, this invention simultaneously promotes the accumulation of antioxidant functional components such as polysaccharides, flavonoids, and phenolic acids through the metabolic activities of Poria cocos. The antioxidant capacity of FRAP is increased from about 0.68 to more than 2.85 μmol Trolox / g, and the antioxidant capacity of ABTS is increased from about 13.09 to more than 18.92 μmol Trolox / g, achieving synergistic optimization of fiber modification and functional component enhancement.

[0027] 3. The fermentation process of this invention is green and environmentally friendly. It does not require the addition of expensive chemical reagents or enzyme preparations. It only utilizes the metabolic capacity of microorganisms to complete the modification of raw materials, which significantly reduces production costs and avoids food safety hazards caused by chemical reagent residues.

[0028] 4. This invention adopts a semi-solid fermentation process, which has better mass and heat transfer performance compared with traditional solid fermentation, saves water and energy compared with liquid fermentation, is easy to operate, has a fixed and controllable fermentation cycle (about 14 days), and produces stable product quality, making it suitable for large-scale industrial production.

[0029] 5. This invention further provides a preferred scheme for fermentation using compound strains. Utilizing the synergistic effect of *Poria cocos* P5.78 and *Poria cocos* Xiangjing 28, the soluble dietary fiber content and antioxidant properties of the product can be further improved. Experimental data show that under the fermentation conditions of the compound strains, the soluble dietary fiber content can be further increased to over 15%, and the antioxidant capacity (FRAP) can reach over 3.50 μmol Trolox / g, significantly better than the fermentation effect of a single strain.

[0030] 6. Fermentation products can be widely used in functional foods, dietary supplements and health foods, which broadens the scope of utilization of bagasse by-products and is of great significance for promoting the resource utilization of by-products in the sugar industry. Detailed Implementation

[0031] To enable those skilled in the art to better implement the present invention, the present invention will be further described below with reference to embodiments. However, it should be understood that the present invention is not limited to the following embodiments.

[0032] For ease of comparison, the raw materials used in the following examples and comparative examples are all from the same batch, and the specific parameters of the raw materials are as follows: Sugarcane bagasse: Purchased commercially. Fresh sugarcane bagasse is initially drained and set aside. The initial moisture content is about 50% to 60%, and the total dietary fiber content is about 70% to 80%, of which the soluble dietary fiber content is about 5%. Poria cocos P5.78: Commercially available, original number P5.78, requires activation culture before use; Poria cocos fungus Xiangjing 28: Commercially available, requires activation culture before use; Deionized water: prepared in the laboratory, resistivity ≥18.2MΩ·cm.

[0033] Methods for activating microbial strains: (1) Take the strain of Poria cocos slant culture, and under aseptic conditions, pick up a loop of mycelium with an aseptic inoculation loop and transfer it to the surface of a potato agar plate (culture medium formula: potato 200g / L, glucose 20g / L, agar 15g / L, pH natural), and spread it evenly.

[0034] (2) Invert the inoculated plate and incubate it in a constant temperature incubator at 28-30℃ for 7-10 days. Once the mycelium has covered the surface of the plate, it can be used for solid fermentation inoculation.

[0035] (3) When using the compound strain, culture the P5.78 strain and the Xiangjing 28 strain separately until the mycelium is fully grown. Pick the mycelium separately at a mass ratio of 1:1, mix them evenly and use them as inoculation strains.

[0036] Example 1 (using a single strain of P5.78): High-value-added sugarcane bagasse dietary fiber raw material was prepared according to the following method: S1. Raw material pretreatment: Place fresh sugarcane bagasse in a constant temperature drying oven and dry at 60℃ for 8 hours until the moisture content is 12%. After removal, crush it with a high-speed universal pulverizer and pass it through a 2 mm sieve to obtain sugarcane bagasse powder with a particle size of 1-2 mm, for later use.

[0037] S2. Sterilization: Weigh 500 g of the sugarcane bagasse powder obtained in step S1, spread it evenly on a high-temperature resistant tray, and place it in a high-pressure steam sterilizer. Sterilize at 121℃ and 0.12 MPa for 20 minutes. After sterilization, remove the material and allow it to cool naturally to 32℃ in a clean environment.

[0038] S3. Strain activation: Following the aforementioned strain activation method, inoculate the Poria cocos P5.78 strain onto a mixed potato agar plate and incubate at 29°C for 8 days until the mycelium covers the entire surface of the plate.

[0039] S4. Inoculation and Fermentation: Using a sterile inoculation spatula, scrape the mycelium from the surface of the plate culture medium that has been fully colonized in step S3. Weigh out the mycelium at an inoculation rate of 5% of the wet weight of the sugarcane bagasse powder (i.e., inoculate 25g of mycelium into 500g of sugarcane bagasse powder), and mix it evenly with the cooled sugarcane bagasse powder from step S2. Add sterile deionized water to adjust the moisture content of the material to 60%, and mix thoroughly.

[0040] S5. Semi-solid fermentation: Transfer the inoculated material into a sterile shallow-plate fermentation container, controlling the material layer thickness to 3–4 cm. Place the shallow plate in a constant temperature and humidity incubation chamber, controlling the temperature at 29℃ and the humidity at 65%, for semi-solid fermentation. The fermentation cycle is 14 days. During fermentation, stir the material every 2 days, observing the moisture content each time. If necessary, spray a small amount of sterile deionized water to maintain the moisture content within the range of 58%–62%. Record the material temperature, ambient humidity, and pH value daily to ensure environmental stability.

[0041] S6. Product Processing: After fermentation, the fermented material is transferred to a constant temperature drying oven and dried with hot air at 60℃ for 10 hours until the moisture content of the material is 11%. The dried material is then pulverized using a high-speed universal pulverizer, passed through a 60-mesh sieve, and the sieve-passing material is collected to obtain the high-value-added sugarcane bagasse dietary fiber raw material. The weight is recorded, and the sample is sealed and stored for later use. This sample is designated as Sample 1.

[0042] Example 2: The same steps as in Example 1 were followed, with the difference being adjustments to the fermentation period and moisture content. The specific plan is as follows: S1 to S3 are the same as in Example 1.

[0043] S4. Inoculation and Fermentation: Using a sterile inoculation spatula, scrape the mycelium from the surface of the plate that has been fully covered with mycelium. Weigh out 25g of mycelium at a wet substrate inoculation rate of 5% and mix it evenly with sugarcane bagasse powder. Add sterile deionized water to adjust the moisture content of the material to 55% and mix evenly.

[0044] S5, Semi-solid fermentation: Control the temperature at 28℃ and the humidity at 60%, with a fermentation cycle of 12 days. Stir the mixture every 3 days during the fermentation process.

[0045] S6. Product processing: After fermentation, the product is dried in hot air at 50℃ for 14 hours until the moisture content is 10%, and then pulverized through a 40-mesh sieve. The obtained product is designated as Sample 2.

[0046] Example 3: The procedure is the same as in Example 1, except that the inoculum size, fermentation cycle, and moisture content are adjusted. The specific plan is as follows: S1 to S3 are the same as in Example 1.

[0047] S4. Inoculation and Fermentation: Using a sterile inoculation spatula, scrape the mycelium from the surface of the plate that has been covered with mycelium. Weigh out 50g of mycelium at an inoculation rate of 10% on a wet substrate and mix it evenly with sugarcane bagasse powder. Add sterile deionized water to adjust the moisture content of the material to 65% and mix evenly.

[0048] S5, Semi-solid fermentation: Control the temperature at 32℃ and the humidity at 70%, with a fermentation cycle of 18 days. Stir the mixture every 2 days during the fermentation process.

[0049] S6. Product processing: After fermentation, the product was dried in hot air at 65℃ for 8 hours until the moisture content was 12%, and then pulverized through a 100-mesh sieve. The obtained product is designated as Sample 3.

[0050] Example 4 (using a combination of P5.78 and Xiangjing 28 strains): High-value-added sugarcane bagasse dietary fiber raw material was prepared according to the following method: S1. Raw material pretreatment: Same as step S1 in Example 1.

[0051] S2. Sterilization treatment: Same as step S2 in Example 1.

[0052] S3. Strain Activation: Following the aforementioned strain activation method, activate *Poria cocos* strain P5.78 and *Poria cocos* strain Xiangjing 28, respectively. Inoculate both onto potato agar plates and incubate at 29°C for 8 days, until the mycelium fully covers the plate surface.

[0053] S4. Inoculation with the composite strain: Using a sterile inoculation spatula, scrape off the mycelium from the surface of the P5.78 plate that has been fully colonized with mycelium in step S3. Separately, use the same spatula to scrape off the mycelium from the surface of the Xiangjing 28 plate. Weigh out the two types of mycelium at a 1:1 mass ratio (i.e., the total inoculation amount is 6% wet substrate, with 15g of P5.78 mycelium and 15g of Xiangjing 28 mycelium, corresponding to 500g of bagasse powder). Mix the two types of mycelium thoroughly, then mix them thoroughly with the cooled bagasse powder from step S2. Add sterile deionized water to adjust the moisture content of the material to 60%, and mix thoroughly.

[0054] S5, Semi-solid fermentation: Same as step S5 in Example 1.

[0055] S6. Product processing: Same as step S6 in Example 1. The obtained product is designated as sample 4.

[0056] Comparative Example 1 (Unfermented Blank Control): This comparative example serves as a control experiment for Example 1, and is conducted according to the same steps as Example 1, except that no microbial strains are inoculated during fermentation. The specific procedure is as follows: S1. Raw material pretreatment: Same as step S1 in Example 1.

[0057] S2. Sterilization treatment: Same as step S2 in Example 1 (no further inoculation after sterilization).

[0058] S3, Blank control (no inoculation): The sugarcane bagasse powder cooled in step S2 was directly processed without adding any bacterial strains.

[0059] S4. Semi-solid "fermentation" (simulation): Transfer uninoculated sugarcane bagasse powder into a sterile shallow dish container and place it under the same environmental conditions (temperature 29℃, humidity 65%) for 14 days, stirring once every 2 days.

[0060] S5. Product processing: Same as step S6 in Example 1. The obtained product is designated as control sample D1 (unfermented control).

[0061] Comparative Example 2 (using Bacillus subtilis as a substitute): This comparative example serves as a control experiment for Example 1, and is conducted according to the same steps as Example 1, except that Bacillus subtilis, a commonly used biotechnology molecule in the prior art, is used instead of Poria cocos P5.78 for fermentation. The specific scheme is as follows: S1. Raw material pretreatment: Same as step S1 in Example 1.

[0062] S2. Sterilization treatment: Same as step S2 in Example 1.

[0063] S3. Activation of Alternative Bacterial Strains: Commercially available Bacillus subtilis strain was selected and activated according to the standard activation method for this strain (37℃, nutrient broth medium activation for 24 hours) to prepare a bacterial suspension (viable count approximately 1.0 × 10⁻⁶). 8 (CFU / mL).

[0064] S4. Inoculation and Fermentation: Inoculate the Bacillus subtilis suspension activated in step S3 into sugarcane bagasse powder at an inoculation rate of 5% by wet weight (i.e., add 25mL of bacterial suspension to 500g of sugarcane bagasse powder), add sterile deionized water to adjust the moisture content of the material to 60%, and mix evenly.

[0065] S5, Semi-solid fermentation: Control the temperature at 37℃ and the humidity at 60%, with a fermentation cycle of 7 days (the standard cycle for Bacillus subtilis solid-state fermentation). Stir once every day during the fermentation process.

[0066] S6. Product processing: Same as step S6 in Example 1. The obtained product is designated as control sample D2.

[0067] Comparative Example 3 (using Aspergillus niger as a substitute): This comparative example serves as a control experiment for Example 1, and is conducted according to the same steps as Example 1, except that Aspergillus niger, as reported in the prior art, is used instead of Poria cocos P5.78 for fermentation. The specific scheme is as follows: S1. Raw material pretreatment: Same as step S1 in Example 1.

[0068] S2. Sterilization treatment: Same as step S2 in Example 1.

[0069] S3. Activation of alternative strains: Commercially available Aspergillus niger strain was selected and activated according to the conventional activation method of this strain (cultured on potato dextrose agar medium at 28℃ for 6 days).

[0070] S4. Inoculation and Fermentation: Use a sterile inoculation spatula to scrape the mycelium from the surface of the Aspergillus niger plate that has been covered with mycelium, and inoculate it into the sugarcane bagasse powder at an inoculation rate of 5% by wet weight. Add sterile deionized water to adjust the moisture content of the material to 60% and mix evenly.

[0071] S5, Semi-solid fermentation: Control the temperature at 30℃ and the humidity at 65%, with a fermentation cycle of 7 days. Stir the mixture every 2 days during the fermentation process.

[0072] S6. Product processing: Same as step S6 in Example 1. The obtained product is designated as control sample D3.

[0073] Comparative Example 4 (P5.78 only, inoculation amount 6%, same as the total inoculation amount in Example 4): This comparative example serves as the control experiment for Example 4, and is conducted according to the same steps as Example 4, except that only *Poria cocos* P5.78 is used in the compound strain, excluding *Xiangjing 28* strain (i.e., the total amount of strain used is the same as in Example 4). The specific scheme is as follows: S1. Raw material pretreatment: Same as step S1 in Example 4.

[0074] S2. Sterilization treatment: Same as step S2 in Example 4.

[0075] S3. Strain activation: Activate the Poria cocos strain P5.78 according to the strain activation method in Example 4.

[0076] S4. Single-strain inoculation: Use a sterile inoculation spatula to scrape the mycelium from the surface of the P5.78 plate that has been covered with mycelium, and inoculate it into the bagasse powder at an inoculation amount of 6% by wet weight (i.e., 30g of P5.78 mycelium is inoculated into 500g of bagasse powder, and the total inoculation amount is the same as in Example 4). Add sterile deionized water to adjust the moisture content of the material to 60%, and mix evenly.

[0077] S5-S6 are the same as in Example 4. The obtained product is designated as Comparative Sample D4.

[0078] Comparative Example 5 (Xiangjing 28 only, inoculation amount 6%, the same as the total inoculation amount in Example 4): This comparative example serves as the control experiment for Example 4, and is conducted according to the same steps as Example 4, except that only *Poria cocos* strain Xiangjing 28 is used in the compound strain, excluding strain P5.78 (i.e., the total amount of strain used is the same as in Example 4). The specific scheme is as follows: S1. Raw material pretreatment: Same as step S1 in Example 4.

[0079] S2. Sterilization treatment: Same as step S2 in Example 4.

[0080] S3. Strain activation: The strain of Poria cocos Xiangjing 28 was activated according to the strain activation method in Example 4.

[0081] S4. Single strain inoculation: Use a sterile inoculation spatula to scrape the mycelium from the surface of the Xiangjing 28 plate that has been covered with mycelium, and inoculate it into sugarcane bagasse powder at an inoculation amount of 6% by wet weight (i.e., 30g of Xiangjing 28 mycelium is inoculated into 500g of sugarcane bagasse powder, and the total inoculation amount is the same as in Example 4). Add sterile deionized water to adjust the moisture content of the material to 60%, and mix evenly.

[0082] S5 to S6 are the same as in Example 4. The obtained product is designated as comparative sample D5.

[0083] Comparative Example 6 (GTR1 only, inoculation amount 6%, same as the total inoculation amount in Example 4): This comparative example serves as a control experiment for Example 4, and is conducted according to the same steps as Example 4, except that only *Poria cocos* GTR1 is used, and strains P5.78 and Xiangjing 28 are not used (the total number of strains used is the same as in Example 4). The specific protocol is as follows: S1. Raw material pretreatment: Same as step S1 in Example 4.

[0084] S2. Sterilization treatment: Same as step S2 in Example 4.

[0085] S3. Strain activation: Activate the Poria cocos GTR1 strain according to the strain activation method in Example 4.

[0086] S4. Single strain inoculation: Use a sterile inoculation spatula to scrape the mycelium from the surface of the GTR1 plate that has been covered with mycelium, and inoculate it into sugarcane bagasse powder at an inoculation amount of 6% by wet weight (i.e., 30g of GTR1 mycelium is inoculated into 500g of sugarcane bagasse powder, and the total inoculation amount is the same as in Example 4). Add sterile deionized water to adjust the moisture content of the material to 60%, and mix evenly.

[0087] S5-S6 are the same as in Example 4. The product obtained is designated as Comparative Sample D6.

[0088] Comparative Example 7 (using Poria cocos strain GTR1 instead of Xiangjing 28): This comparative example serves as the control experiment for Example 4, and is conducted according to the same steps as Example 4, except that the *Poria cocos* strain Xiangjing 28 in the composite strain is replaced with an equal amount of *Poria cocos* strain GTR1. The specific procedure is as follows: S1. Raw material pretreatment: Same as step S1 in Example 4.

[0089] S2. Sterilization treatment: Same as step S2 in Example 4.

[0090] S3. Strain activation: The strains of Poria cocos P5.78 and Poria cocos GTR1 were activated according to the strain activation method in Example 4.

[0091] S4. Inoculation with alternative compound strains: Weigh 15g of P5.78 mycelium and 15g of GTR1 mycelium at a mass ratio of 1:1, mix them evenly, and then inoculate them into 500g of sugarcane bagasse powder. Add sterile deionized water to adjust the moisture content of the material to 60% and mix evenly.

[0092] S5-S6 are the same as in Example 4. The product obtained is designated as comparative sample D7.

[0093] Comparative Example 8 (using yeast instead of Xiangjing 28): This comparative example serves as a control experiment for Example 4, and is conducted according to the same steps as Example 4, except that the *Poria cocos* strain Xiangjing 28 in the compound strain is replaced with an equal amount of yeast, thereby verifying the specificity of the compound strain combination. The specific procedure is as follows: S1. Raw material pretreatment: Same as step S1 in Example 4.

[0094] S2. Sterilization treatment: Same as step S2 in Example 4.

[0095] S3. Activation of strains: Activate Poria cocos P5.78 according to the strain activation method in Example 4; and activate commercially available Saccharomyces cerevisiae according to the conventional activation method for yeast (28°C, yeast extract peptone glucose medium culture for 36 hours).

[0096] S4. Inoculation with alternative compound strains: Weigh 15g of P5.78 mycelium and 15g of yeast sludge at a mass ratio of 1:1, mix them evenly, and then inoculate them into 500g of sugarcane bagasse powder. Add sterile deionized water to adjust the moisture content of the material to 60% and mix evenly.

[0097] S5, Semi-solid fermentation: Same as step S5 in Example 4.

[0098] S6. Product processing: Same as step S6 in Example 4. The obtained product is designated as control sample D8.

[0099] Performance verification experiment: The sugarcane bagasse dietary fiber raw materials prepared in Examples 1 to 4 and Comparative Examples 1 to 8 were subjected to component analysis and antioxidant activity determination, respectively.

[0100] 1. Determination of soluble dietary fiber (SDF) content The determination was performed using the enzyme gravimetric method as specified in GB 5009.88-2014, "National Food Safety Standard - Determination of Dietary Fiber in Food".

[0101] 2. Antioxidant capacity determination (1) FRAP method (ferric reduction / antioxidant capacity method): Refer to the method of Benzie and Strain. Take an appropriate amount of sample and extract with 80% ethanol. Take the supernatant and mix it with FRAP working solution (containing 2.5 mL 10 mmol / L TPTZ solution, 2.5 mL 20 mmol / L FeCl3 solution, 25 mL 0.3 mol / L acetate buffer, pH 3.6). After reacting at 37℃ for 30 min, measure the absorbance at 593 nm. Trolox was used as the standard. The results are expressed as μmol Trolox / g sample.

[0102] (2) ABTS method: Refer to the method of Re et al. ABTS is reacted with potassium persulfate to generate ABTS. + The free radical stock solution was diluted with ethanol to an absorbance of 0.70 ± 0.02 at 734 nm. An appropriate amount of sample extract was mixed with ABTS working solution, and the absorbance was measured at 734 nm after reacting for 6 min. Results are expressed as μmol Trolox / g sample.

[0103] 3. Determination of total polysaccharide content Following the phenol-sulfuric acid method, take an appropriate amount of sample, add deionized water, boil and extract for 2 hours, centrifuge and collect the supernatant. Add phenol and concentrated sulfuric acid to the supernatant, and measure the absorbance at 490 nm. Calculate the total polysaccharide content using glucose as a standard.

[0104] 4. Determination of total flavonoid content Refer to the sodium nitrite-aluminum nitrate method. Take an appropriate amount of sample extract, add 5% NaNO2 solution, 10% Al(NO3)3 solution and 1 mol / L NaOH solution in sequence, and measure the absorbance at 510 nm. Calculate the total flavonoid content using rutin as a standard.

[0105] 5. Determination of total phenol content Refer to the Folin-phenol method. Take an appropriate amount of sample extract, add Folin-phenol reagent and 7.5% Na2CO3 solution, and measure the absorbance at 765 nm. Calculate the total phenol content using gallic acid as a standard.

[0106] Each of the above measurements was repeated 5 times, and the average value was taken. The experimental results are shown in Table 1 and Table 2.

[0107] Table 1. Effects of different treatments on the soluble dietary fiber content and antioxidant capacity of sugarcane bagasse dietary fiber raw material. Table 2. Effects of different treatments on the content of total polysaccharides, total flavonoids, and total phenols in sugarcane bagasse dietary fiber raw materials. Summary of performance verification experiments The following conclusions can be drawn from the results in Tables 1 and 2: 1. The method of this invention significantly improves the soluble dietary fiber content and antioxidant capacity of sugarcane bagasse. A comparison between Example 1 and Comparative Example 1 shows that the soluble dietary fiber content of unfermented sugarcane bagasse is only 5.1%, the FRAP antioxidant capacity is 0.70 μmol Trolox / g, and the ABTS antioxidant capacity is 13.21 μmol Trolox / g. After treatment with the method of this invention (Poria cocos P5.78, fermentation for 14 days), the soluble dietary fiber content increased to 13.2%, FRAP increased to 2.88 μmol Trolox / g, and ABTS increased to 19.01 μmol Trolox / g, representing increases of approximately 159%, 311%, and 44%, respectively. The contents of polysaccharides, total flavonoids, and total phenols increased from 68.5 mg / g, 3.51 mg RE / g, and 5.26 mg GAE / g to 185.6 mg / g, 8.42 mg RE / g, and 12.35 mg GAE / g, respectively, representing increases of approximately 171%, 140%, and 135%. This indicates that the method of the present invention not only achieves efficient conversion of soluble dietary fiber but also simultaneously enhances the antioxidant functional components of sugarcane bagasse.

[0108] 2. Influence of Fermentation Parameters. Comparing the experimental results of Example 1 (14 days, 60% moisture content), Example 2 (12 days, 55% moisture content), and Example 3 (18 days, 65% moisture content), all indicators of Example 1 were superior to those of Examples 2 and 3, indicating that a fermentation cycle of 14 days and a material moisture content of 60% are the optimal combination of process parameters. The accumulation of functional components was not complete at 12 days of fermentation, and the improvement in indicators was limited at 18 days, suggesting that 14 days is the optimal fermentation cycle.

[0109] 3. The method of this invention is superior to other existing microbial fermentation methods. Comparing Example 1 with Comparative Example 2 (Bacillus subtilis) and Comparative Example 3 (Aspergillus niger), although Bacillus subtilis (13.9%) had a slightly higher soluble dietary fiber content than the method of this invention (13.2%), the FRAP (2.88) of the method of this invention was significantly higher than that of Bacillus subtilis (1.96) and Aspergillus niger (2.15), and the ABTS (19.01) was significantly higher than that of Bacillus subtilis (16.53) and Aspergillus niger (17.02). In terms of total polysaccharide, total flavonoid, and total phenolic content, the indicators of the method of this invention were also significantly superior to those of Bacillus subtilis and Aspergillus niger fermentation. This indicates that, compared with other existing microbial fermentation methods, the *Poria cocos* strain used in this invention can not only efficiently convert soluble dietary fiber in a semi-solid fermentation system, but also has unique advantages in the accumulation of antioxidant active ingredients.

[0110] 4. The specific combination of P5.78 and Xiangjing 28 produced a significant synergistic effect. Under the premise that the total amount of strains used was exactly the same, all indicators of Example 4 (P5.78 and Xiangjing 28 in a 1:1 ratio) were significantly higher than the effects of Comparative Example 4 (P5.78 only) and Comparative Example 5 (Xiangjing 28 only) when used alone, and far exceeded the theoretical sum of the two. Specifically: the theoretical sum of soluble dietary fiber content was (13.4% + 9.7%) / 2 ≈ 11.55%, while the measured value was 15.3%, with a synergistic increase of 3.75 percentage points (an increase of approximately 32%); the theoretical sum of FRAP was (2.91 + 1.98) / 2 ≈ 2.445 μmol Trolox / g, while the measured value was 3.57 μmol Trolox / g, with a synergistic increase of 1.125 μmol Trolox / g (an increase of approximately 46%); and the theoretical sum of ABTS was (19.23 + 15.86) / 2 ≈ 17.545 μmol Trolox / g, while the measured value was 22.68 μmol Trolox / g, with a synergistic increase of 5.135 μmol Trolox / g (an increase of approximately 29%). This indicates that the two components formed metabolic complementarity in the fermentation system, producing a significant synergistic effect. The inventors believe the reason may be that in the semi-solid fermentation system, the mycelia of strains P5.78 and Xiangjing 28 intertwine, forming a spatially complementary microecological interface. The extracellular cellulase system secreted by strain P5.78 has high hemicellulose side chain degradation activity, which can preferentially hydrolyze arabinoxylan and glucomannan in sugarcane bagasse, exposing more free reducing ends and microfibril gaps. This localized fiber structure dissociation provides more accessible sites of action for the endoglucanase and β-glucosidase secreted by strain Xiangjing 28, which have unique substrate preferences. Furthermore, the two strains may mutually induce each other at the level of metabolite exchange. Specific oligosaccharide fragments produced by P5.78 metabolism can act as signaling molecules, upregulating the expression of genes related to polyphenol and flavonoid biosynthesis (such as phenylalanine ammonia-lyase PAL and chalcone synthase CHS) in Xiangjing 28. Meanwhile, while accumulating antioxidant secondary metabolites, Xiangjing 28 releases certain small molecule phenolic acids (such as caffeic acid and ferulic acid), which can in turn regulate the conformation of the cellulase system in P5.78, further enhancing its catalytic efficiency. This bidirectional interaction mechanism based on the synergistic deconstruction of cell structure and the cross-activation of metabolic signals allows the two strains to form a positive feedback loop of catalytic efficiency and functional product synthesis in the same solid matrix, ultimately exhibiting a significant synergistic effect.

[0111] 5. Validation of the specificity of the combined strains. Data from Comparative Example 6 (GTR1 only) shows that the SDF of GTR1 fermentation alone was 11.3%, and the FRAP was 2.14, both lower than P5.78 (13.4% SDF, 2.91 FRAP), but still higher than Xiangjing 28 (9.7% SDF, 1.98 FRAP). However, when GTR1 and P5.78 were combined in a 1:1 ratio (Comparative Example 7), the SDF was only 11.8%, lower than not only Comparative Example 4 (P5.78 only, 13.4%), but also lower than the simple arithmetic mean of Comparative Examples 6 and 4 (approximately 12.4%), showing no synergistic effect. FRAP, ABTS, total polysaccharides, and other indicators were also lower than in Comparative Example 4. This indicates that P5.78 and GTR1 had a negative interaction in the fermentation system due to interstrain somatic cell incompatibility or metabolic competition, resulting in the fermentation effects being mutually canceled out. The effect of Comparative Example 8 (P5.78 + yeast) was even worse (SDF only 8.6%). These results fully demonstrate that the synergistic effect between P5.78 and Xiangjing 28 discovered in this invention has a high degree of specificity.

Claims

1. A method for preparing high-value-added sugarcane bagasse dietary fiber raw material using Poria cocos semi-solid fermentation, characterized in that, Includes the following steps: A. Raw material pretreatment: Dry the sugarcane bagasse to a moisture content of 10% to 15% by weight, and crush it to a particle size of 1 to 3 mm to obtain sugarcane bagasse powder; B. Sterilization treatment: Sterilize or treat the sugarcane bagasse powder obtained in step A at high temperature for a short time, and then cool it to 30-35°C. C. Inoculation and fermentation: Inoculate the cooled sugarcane bagasse powder with Poria cocos strain, the inoculation amount is 5% to 10% of the wet weight of the sugarcane bagasse powder, and mix evenly; the Poria cocos strain includes Poria cocos P5.78; D. Semi-solid fermentation: After inoculation, the material is transferred into a fermentation tank. The moisture content of the material is adjusted to 55% to 65%. The temperature is maintained at 28 to 32°C and the humidity at 60% to 70%. Semi-solid fermentation is carried out, and the fermentation cycle is 12 to 18 days. During the fermentation process, the material is turned over once every 2 to 3 days. The fermentation environment is kept stable by monitoring pH, temperature and humidity. E. Product processing: After fermentation, the fermented material is dried to a moisture content of 10% to 12%, crushed and sieved to obtain high-value-added sugarcane bagasse dietary fiber raw material.

2. The preparation method according to claim 1, characterized in that, The *Poria cocos* strain consists of *Poria cocos* P5.78 and *Poria cocos* Xiangjing 28, with a mass ratio of *Poria cocos* P5.78 to *Poria cocos* Xiangjing 28 of 1:0.4 to 1.

3.

3. The preparation method according to claim 1, characterized in that, In step A, the drying temperature is 50–70°C and the drying time is 6–12 hours.

4. The preparation method according to claim 1, characterized in that, In step A, the pulverization is carried out using a mechanical pulverizer.

5. The preparation method according to claim 1, characterized in that, In step B, the sterilization process is high-pressure steam sterilization, with a sterilization temperature of 120–122°C and a sterilization time of 15–30 minutes.

6. The preparation method according to claim 1, characterized in that, The fermentation cycle in step D is 14 days; the moisture content of the semi-solid fermentation material in step D is 58% to 62%.

7. The preparation method according to claim 1, characterized in that, In step E, hot air drying is used, with a drying temperature of 50-65℃ and a drying time of 8-14 hours.

8. The preparation method according to claim 1, characterized in that, In step E, sieving is performed using a 40-100 mesh sieve.

9. A high-value-added sugarcane bagasse dietary fiber raw material prepared by any one of the preparation methods described in claims 1 to 8.

10. The application of the high-value-added sugarcane bagasse dietary fiber raw material according to claim 9 in the preparation of functional foods, dietary supplements or antioxidant health products.

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