A bamboo shoot residue processing method for synergistically improving soluble dietary fiber and its combined polyphenol content

Abstract

This invention discloses a method for processing bamboo shoot residue that synergistically enhances the content of soluble dietary fiber and its bound polyphenols. Using waste bamboo shoot residue as raw material, the fermentation bacteria are all food-grade. Specifically, a multi-strain coupled fermentation is employed, including *Bacillus belye*, *Bacillus natto*, *Trichoderma kangsei*, *Cladosporium*, *Aspergillus pamoateus*, and *Bacillus coagulans*. This significantly alters the ratio and content of soluble and insoluble dietary fiber in the bamboo shoot residue and substantially increases the content of dietary fiber-bound polyphenols, synergistically enhancing the content of soluble dietary fiber and its bound polyphenols, thereby producing high-quality dietary fiber. This invention is simple to operate, low in cost, and allows for easier control of fermentation conditions. It is highly efficient and does not easily damage the non-covalent bonds (hydrogen bonds, electrostatic or ionic bonds, etc.) or covalent bonds (ester bonds, ether bonds, etc.) binding dietary fiber and polyphenols. It also has no significant impact on the pH and temperature of the environment, and can significantly increase the content of soluble dietary fiber and its bound polyphenols in bamboo shoot residue.

Description

Technical Field

[0001] This invention belongs to the field of food and agricultural product processing technology, and relates to a method for processing bamboo shoot residue that synergistically enhances the content of soluble dietary fiber and its bound polyphenols. Background Technology

[0002] Bamboo shoot residue, a processing byproduct of bamboo shoots including the shoot tips and husks, accounts for 60%–70% of the entire bamboo shoot. Studies have shown that the nutritional composition of bamboo shoot residue is similar to that of bamboo shoots, mainly including protein, dietary fiber, amino acids, polyphenols, vitamins, and minerals. In particular, bamboo shoot residue is rich in dietary fiber, with total dietary fiber content in dried bamboo shoot residue reaching 60%–65%. Bamboo shoot dietary fiber, an important component of bamboo shoots, is mainly composed of cellulose, lignin, and hemicellulose, and possesses various biological activities such as lowering blood cholesterol, regulating blood sugar, reducing inflammation, preventing obesity, and enhancing intestinal function. Furthermore, bamboo shoot polyphenols are also important bioactive substances in bamboo shoots, exhibiting good antioxidant, anti-tumor, anti-inflammatory, antidepressant, and cholesterol-regulating physiological functions.

[0003] Dietary fiber is classified into soluble and insoluble dietary fiber based on its solubility. Soluble dietary fiber is mainly composed of gums, pectin, and hemicellulose. Studies have shown that soluble dietary fiber dissolves in water and has high viscosity, enabling it to adsorb glucose, cholesterol, nitrites, lead, mercury, etc., thereby slowing down the absorption of sugars, lipids, and harmful substances. Furthermore, soluble dietary fiber can be almost completely fermented by intestinal bacteria, and the resulting butyric acid can inhibit the tendency of epithelial cells to deteriorate, preventing health problems such as diabetes, hypertension, and hyperglycemia. Insoluble dietary fiber is mainly composed of plant cell wall structures such as cellulose, hemicellulose, and lignin. It has high water-holding capacity and swelling power, which can enhance satiety and promote intestinal peristalsis, thereby limiting food intake and achieving the effects of weight loss and preventing constipation. In addition, polyphenols combined with dietary fiber have more stable biological activity than free polyphenols, and have physiological functions such as anti-oxidation, antibacterial, anti-inflammatory, blood sugar and lipid reduction, thereby enhancing the physiological and biochemical functions of dietary fiber. Studies have shown that most of the bound polyphenols can be carried to the colon by dietary fiber, and are released and decomposed by the human body through the action of microbial flora.

[0004] It is generally believed that high-quality dietary fiber should contain at least 10% soluble dietary fiber. However, in bamboo shoots, insoluble dietary fiber accounts for as much as 92%, which may adversely affect the color, texture, and taste of food when used as a raw material or functional ingredient. In recent years, to improve the quality of bamboo shoot dietary fiber and expand its application range, researchers at home and abroad have successively used methods such as acid-base methods, microbial methods, enzymatic methods, and physical-mechanical methods to modify it, thereby increasing the content of soluble dietary fiber. In addition, the binding of dietary fiber with polyphenols in bamboo shoots has also attracted increasing attention. Free phenols in bamboo shoots bind with dietary fiber through ester bonds, ether bonds, and hydrogen bonds, thereby improving the chemical stability of polyphenols. On the other hand, the binding effect of dietary fiber reduces the release of polyphenols in the gastrointestinal tract, reducing their bioavailability. Therefore, increasing the content of soluble dietary fiber and dietary fiber-bound polyphenols in bamboo shoots is of great significance for improving the utilization value of bamboo shoots.

[0005] Patent application CN103462042A discloses a method for preparing dietary fiber from bamboo shoots using microbial fermentation. Using waste scraps generated during bamboo shoot processing as raw material, mold seed liquid or lactic acid bacteria seed is added and fermented at a constant temperature of 38-42℃ for about 3 days, thereby increasing the soluble dietary fiber content, water-holding capacity, and swelling capacity of the bamboo shoot residue. However, this method uses a single microbial strain, resulting in a significantly lower fermentation rate compared to multi-strain fermentation, and consequently, a lower yield of soluble dietary fiber. Furthermore, this patent does not further investigate the content of polyphenols bound to the dietary fiber.

[0006] Patent application CN116391879A discloses a method for improving the bioavailability of bamboo shoot dietary fiber and polyphenols through compounding. The method involves treating bamboo shoots with amylase and alkaline protease to obtain bamboo shoot residue, followed by microwave enzyme inactivation, vacuum drying, and high-voltage electrostatic treatment to obtain positively charged fiber powder. This powder is then added to an acidic polyphenol solution, stirred to form a suspension, filtered, and the residue is freeze-dried to obtain the bamboo shoot dietary fiber and polyphenol complex. However, the enzymes used in this method require specific pH, temperature, and time conditions to maintain their activity, making the reaction conditions demanding. Furthermore, the focus of this invention is on improving the adsorption capacity and stability of polyphenols by bamboo shoot dietary fiber to obtain the bamboo shoot dietary fiber and polyphenol complex, without further research on increasing the content of dietary fiber and bound polyphenols. Summary of the Invention

[0007] In view of this, the purpose of this invention is to provide a bamboo shoot residue processing method that synergistically enhances the content of soluble dietary fiber and its bound polyphenols. The method utilizes a multi-strain coupled fermentation technology, including Bacillus belye, Bacillus natto, Trichoderma kangsei, Cladosporium cladosporium, Aspergillus pamomori, and Bacillus coagulans, to process bamboo shoot residue, ultimately synergistically enhancing the content of soluble dietary fiber and dietary fiber bound polyphenols in the bamboo shoot residue.

[0008] To achieve the above objectives, the present invention provides the following technical solution:

[0009] A method for processing bamboo shoot residue that synergistically enhances the content of soluble dietary fiber and its bound polyphenols includes the following specific steps:

[0010] (1) First, the waste bamboo shoot residue is dried, pre-crushed and ball-milled to obtain bamboo shoot residue powder;

[0011] (2) Then, Bacillus berleis, Bacillus natto and Trichoderma kangsei were cultured and activated in a shaker and mixed to obtain the first compound bacterial culture solution; Cladosporium argentis, Aspergillus fossa and Bacillus coagulans were cultured and activated in a shaker and mixed to obtain the second compound bacterial culture solution.

[0012] (3) Then mix the bamboo shoot residue powder with purified water, sterilize, adjust the pH to 5.5-7.5, inoculate with the first compound bacterial culture liquid, carry out the first stage of fermentation, and sterilize.

[0013] (4) Adjust the pH to 5.5-6.5, inoculate with the second compound bacterial culture, carry out the second stage of fermentation, sterilize, and freeze dry under vacuum.

[0014] Preferably, in step (1), the waste bamboo shoot residue includes, but is not limited to, the following edible bamboo shoot production and processing waste: moso bamboo shoots, hemp bamboo shoots, and square bamboo shoots.

[0015] Preferably, in step (1), the drying process conditions are: drying at 60-80℃ to a moisture content of 8-10 w.t.%.

[0016] Preferably, in step (1), a pulverizer is first used to perform preliminary pulverization to obtain coarse powder, and then a planetary ball mill is used for ball milling. The rotation speed of the ball mill is 300-450 r / min, the ball milling time is 3-5 hours, the ratio of large balls to small balls is 1:2-5, the ball-to-material mass ratio is 2-4:1, the diameter of the large balls is 10 mm, and the diameter of the small balls is 3 mm.

[0017] Preferably, in step (1), the average particle size of the bamboo shoot residue powder is 11.5 to 23.6 μm.

[0018] Preferably, in step (2), Bacillus belye, Bacillus natto, Trichoderma koningii, Cladosporium cladosporium, Aspergillus buergerianum, or Bacillus coagulans are inoculated into MRS liquid culture medium and cultured and activated in a shaker. The ratio of bacterial strain to MRS liquid culture medium is 0.25-0.5g:40mL.

[0019] Preferably, in step (2), the process conditions for shaking culture and activation are: temperature 35-37℃, rotation speed 240-270rpm, and culture time 24-48 hours.

[0020] Preferably, in step (2), the first compound bacterial culture solution is prepared by the following method: Bacillus belye, Bacillus natto, and Trichoderma kangsei are first activated by shaking culture in a shaker to obtain the corresponding bacterial culture solution, and then mixed in a volume ratio of 1:1:2 to 5; the second compound bacterial culture solution is prepared by the following method: Cladosporium argentis, Aspergillus fossa, and Bacillus coagulans are first activated by shaking culture in a shaker to obtain the corresponding bacterial culture solution, and then mixed in a volume ratio of 1:1:2 to 5.

[0021] Preferably, in step (3), the mass ratio of bamboo shoot residue powder to purified water is 1:10-15, and the volume inoculation amount of the first compound bacterial culture liquid is 1-5%.

[0022] Preferably, in step (3), the process conditions for the first stage of fermentation are: temperature 35-37℃, humidity 55-65%, and fermentation time 2-4 days.

[0023] Preferably, in step (4), the volume of the second compound bacterial culture solution is 1-5%.

[0024] Preferably, in step (4), the process conditions for the second stage of fermentation are: temperature 35-37℃, humidity 55-65%, and fermentation time 5-7 days.

[0025] Preferably, in steps (3) and (4), the sterilization process conditions are: sterilization at 121°C for 15 minutes.

[0026] The beneficial effects of this invention are as follows:

[0027] This invention uses waste bamboo shoot residue (derived from the processing waste of edible bamboo shoots such as moso bamboo shoots, hemp bamboo shoots, and square bamboo shoots) as raw material. All fermentation strains are food-grade, specifically employing a multi-strain coupled fermentation process including *Bacillus belye*, *Bacillus natto*, *Trichoderma kangsei*, *Cladosporium*, *Aspergillus pamoateus*, and *Bacillus coagulans*. This significantly alters the ratio and content of soluble and insoluble dietary fiber in the bamboo shoot residue and substantially increases the content of dietary fiber-bound polyphenols, synergistically enhancing the content of soluble dietary fiber and its bound polyphenols, thereby producing high-quality dietary fiber. This invention not only utilizes multi-strain coupled fermentation but also employs a two-stage fermentation process, significantly improving water retention, swelling capacity, and antioxidant capacity while simultaneously increasing soluble dietary fiber and dietary fiber-bound polyphenols. This invention is simple to operate, low in cost, and the fermentation conditions are easier to control. It is highly efficient and does not easily damage the non-covalent bonds such as hydrogen bonds, electrostatic or ionic bonds, or covalent bonds such as ester bonds and ether bonds that bind dietary fiber and polyphenols. It also has no significant impact on the pH and temperature of the environment and can greatly increase the content of soluble dietary fiber and its bound polyphenols in bamboo shoot residue.

[0028] Regarding raw materials, optimization experiments ultimately determined that bamboo shoot residue powder with an average particle size of 11.5–23.6 μm yielded the best fermentation effect. In terms of microbial strain selection, *Bacillus belye* and *Bacillus natto*, with their antibacterial and preservative advantages, provided excellent fermentation conditions while significantly increasing the content of soluble dietary fiber. *Aspergillus fowleri* and *Cladosporium* played a synergistic role in enhancing the content of dietary fiber-bound polyphenols. Overall, a two-stage coupled fermentation method was adopted to reduce competition and antagonism among the microbial strains, thereby ensuring maximum microbial activity. Therefore, the method of multi-strain coupled fermentation synergistically enhancing the content of soluble dietary fiber and dietary fiber-bound polyphenols in bamboo shoot residue, as employed in this invention, has significant technological advancements and promising application prospects.

[0029] The applicant tested the dietary fiber and dietary fiber-bound polyphenol content of the processed product. The results showed that, compared with unmodified bamboo shoot residue, the soluble dietary fiber content increased significantly from 6.37% to 30.15% and the insoluble dietary fiber content decreased significantly from 37.96% to 9.04% after multi-strain coupled fermentation modification using bamboo shoot residue as raw material. The dietary fiber-bound polyphenol content increased significantly from 14.63 mg GAE / g to 48.91 mg GAE / g (see Table 1). At the same time, compared with the fermentation results using a single strain such as Bacillus belyssus, the content of soluble dietary fiber and dietary fiber-bound polyphenols in bamboo shoot residue modified by multi-strain coupled fermentation was significantly improved.

[0030] Table 1. Content of dietary fiber and conjugated polyphenols in bamboo shoot residue before and after modification.

[0031]

[0032] Microbial fermentation modification of bamboo shoot residue showed significant improvements compared to unmodified bamboo shoot residue. The soluble dietary fiber content increased dramatically from 7.91% to 38.96% after multi-strain coupled fermentation modification, while the insoluble dietary fiber content decreased significantly from 35.52% to 5.40%. The dietary fiber-bound polyphenol content also increased from 12.42 mg GAE / g to 49.96 mg GAE / g (see Table 2). Furthermore, compared to fermentation using a single strain such as Bacillus natto, the soluble dietary fiber and bound polyphenol content in the multi-strain coupled fermentation-modified bamboo shoot residue were significantly increased.

[0033] Table 2. Content of dietary fiber and conjugated polyphenols in bamboo shoot residue before and after modification.

[0034]

[0035] Microbial fermentation modification of bamboo shoot residue showed significant improvements compared to unmodified bamboo shoot residue. The soluble dietary fiber content increased dramatically from 6.05% to 34.71%, while the insoluble dietary fiber content decreased significantly from 35.88% to 6.03%. The dietary fiber-bound polyphenol content also increased from 14.49 mg GAE / g to 45.07 mg GAE / g (see Table 3). Furthermore, compared to fermentation using a single strain such as *Trichoderma koningii*, the soluble dietary fiber and bound polyphenol content in the multi-strain coupled fermentation-modified bamboo shoot residue were significantly increased.

[0036] Table 3. Content of dietary fiber and conjugated polyphenols in bamboo shoot residue before and after modification.

[0037]

[0038] This invention has the following advantages:

[0039] 1. This invention uses fermentation to improve the dietary fiber and dietary fiber-bound polyphenols in bamboo shoot residue. Compared with enzymatic, chemical and physical methods, it is simple to operate, low in cost and high in efficiency.

[0040] 2. The fermentation method used in this invention to treat bamboo shoot residue is more conducive to the stability of polyphenols bound to dietary fiber. pH, ion concentration, and external forces all significantly affect the binding of polyphenols and dietary fiber. Physical methods such as ultrasound, microwaves, and extrusion can easily damage the non-covalent bonds (hydrogen bonds, electrostatic or ionic bonds, etc.) and covalent bonds (ester bonds, ether bonds, etc.) between dietary fiber and polyphenols. Chemical methods for modifying dietary fiber use acids and alkalis that alter the pH of the environment. Too high a pH will break the ester bonds between polyphenols and dietary fiber, while too low a pH will break the ether bonds. Enzymatic methods using cellulase and xylanase can only achieve optimal results at specific pH and temperature conditions, which are difficult to control.

[0041] 3. In this invention, bamboo shoot residue powder with an average particle size of 11.5–23.6 μm is selected as the optimal fermentation condition. If the bamboo shoot residue particle size is less than 11.5 μm, too many active sites are exposed, the porous structure is destroyed, its water-holding capacity is weakened, and nutrients such as amino acids and sugars are more easily lost, which is not conducive to the utilization of substrates by microorganisms. If the bamboo shoot residue powder particle size is greater than 23.6 μm, the degree of fragmentation in the bamboo shoot residue powder is low, the soluble substances in the powder are not easy to flow out, and its dispersibility and solubility in water are low. In addition, its crude fiber content is not conducive to the utilization of nutrients in bamboo shoot residue powder by microorganisms, thus reducing fermentation efficiency.

[0042] 4. The *Bacillus belyss* selected in this invention, in addition to its ability to degrade cellulose, also possesses resistance to acid and salt, exhibiting excellent inhibitory effects against *Staphylococcus aureus*, *Bacillus cereus*, and *Salmonella enterica*. Furthermore, it produces proteases and amylases to break down large molecules in bamboo shoot residue into smaller molecules for microbial utilization. Therefore, *Bacillus belyss* exhibits superior growth characteristics, providing more favorable conditions for fermentation compared to common cellulose-degrading bacilli such as *Bacillus coagulans*, *Bacillus subtilis*, and *Bacillus licheniformis*.

[0043] 5. The Bacillus natto selected in this invention can not only significantly increase the content of soluble dietary fiber, but also promote the growth and reproduction of normal microbiota. Its secondary metabolites, such as bacitracin, polymyxin, 2,6-pyridine dicarboxylic acid and other antibiotics, can inhibit the effects of pathogens such as Salmonella typhimurium, Shigella, and Escherichia coli. At the same time, the antimicrobial protein it produces is also a natural preservative, which provides a guarantee for an excellent fermentation environment.

[0044] 6. Aspergillus buergerianum and Cladosporium argentis work synergistically to increase the content of soluble dietary fiber and dietary fiber-bound phenols, and can also produce phenolic extracts such as caffeic acid, syringic acid and ferulic acid, which enhance the antioxidant capacity of bamboo shoot residue.

[0045] 7. This invention, through extensive innovative experiments, ultimately developed a two-stage coupled fermentation method, reducing competition and antagonism among different microbial strains to ensure maximum viability. The first stage primarily converts insoluble dietary fiber into soluble dietary fiber, providing a usable substrate for the fermentation strains in the second stage. The second stage mainly increases the content of polyphenols bound to dietary fiber, while Bacillus coagulans degrades cellulose, maximizing fermentation efficiency. Compared to physical methods, external forces such as ultra-high pressure, extrusion puffing, and ultra-fine grinding easily break the chemical bonds in dietary fiber, destroying its network structure and reducing its water-holding capacity, adsorption capacity, and other physicochemical properties. In chemical methods, acids and alkalis inhibit the activity of α-amylase, protease, etc., leading to a singular advantage of the modified dietary fiber and competition in the binding of dietary fiber and polyphenols, reducing the binding capacity. Enzymatic methods, using cellulase and xylanase, significantly increase the content of dietary fiber, but have little effect on the binding of dietary fiber and polyphenols. Fermentation methods often use molds and Bacillus to modify dietary fiber, but the competition between multiple bacteria reduces the fermentation rate.

[0046] 8. All strains of the present invention are food-grade, safe and harmless, and improve the utilization rate of raw materials. Attached Figure Description

[0047] To make the objectives, technical solutions, and beneficial effects of this invention clearer, the following drawings are provided for illustration.

[0048] Figure 1 This is a process flow diagram of the present invention. Detailed Implementation

[0049] The preferred embodiments of the present invention will now be described in detail with reference to the accompanying drawings.

[0050] Example 1:

[0051] like Figure 1As shown, using waste bamboo shoot residue from bamboo shoot production and processing as raw material, the bamboo shoot residue was first dried in an oven at 60℃ until the moisture content was 10%. Then, it was placed in a pulverizer for preliminary pulverization to obtain coarse bamboo shoot residue powder. This coarse powder was then further refined using a planetary ball mill. The mill speed was 300 r / min, the milling time was 3 h, the ratio of large to small balls was 1:2, and the ball-to-material mass ratio was 2:1. The average particle size of the bamboo shoot residue powder after planetary ball milling was 23.6 μm. In a sterile operating table, 0.25g each of *Bacillus belye*, *Bacillus natto*, *Trichoderma koningii*, *Cladosporium*, *Aspergillus auramori*, and *Bacillus coagulans* (*Bacillus belye*, *Trichoderma koningii*, *Cladosporium*, and *Aspergillus auramori* were purchased from Shanghai Xuanke Biotechnology Co., Ltd.; *Bacillus natto* and *Bacillus coagulans* were purchased from Shanghai Jiaguan Biotechnology Co., Ltd.) were weighed and added to conical centrifuge tubes containing 40mL of MRS liquid medium. The tubes were then incubated in a shaker incubator at 35℃ and 240rpm for 24 hours to activate the bacteria. 50g of the bamboo shoot residue powder obtained above was weighed and added to pure water at a material-to-liquid mass ratio of 1:10. After stirring evenly, the mixture was sterilized at 121℃ for 15 minutes. The sterilized bamboo shoot residue slurry was then dispensed into 5L fermentation tanks, sealed, and allowed to cool. All of this process was completed in a sterile operating table. The pH of the bamboo shoot residue powder homogenate was adjusted to 5.5. Activated *Bacillus belye*, *Bacillus natto*, and *Trichoderma koningii* were added to form a compound inoculum (volume ratio: *Bacillus belye*: *Bacillus natto*: *Trichoderma koningii* = 1:1:2), with an inoculation amount of 1%. This entire process was performed on a sterile workbench. The fermentation tank was placed in a constant temperature and humidity incubator at 35℃ and 55% humidity for 4 days. After this fermentation stage, the bamboo shoot residue homogenate was sterilized at 121℃ for 15 minutes. The pH of the sterilized bamboo shoot residue homogenate was adjusted to 5.5. Activated *Cladosporium cladosporum*, *Aspergillus avocado*, and *Bacillus coagulans* were added to form a compound inoculum (volume ratio: *Cladosporium cladosporum*: *Aspergillus avocado*: *Bacillus coagulans* = 1:1:2), with an inoculation amount of 1%. This entire process was performed on a sterile workbench. The fermentation tank was placed in a constant temperature and humidity incubator at 35℃ and 55% humidity for 5 days. After this stage of fermentation, the bamboo shoot residue was homogenized and sterilized at 121℃ for 15 minutes. After modification, the bamboo shoot residue homogenate was removed, vacuum freeze-dried, and the dietary fiber content in the bamboo shoot residue was determined.

[0052] The results showed that after modification by multi-strain coupled fermentation of waste bamboo shoot residue from bamboo shoot production, the soluble dietary fiber content increased significantly from 6.03% to 31.72%, and the insoluble dietary fiber content decreased significantly from 38.22% to 10.73%, according to GB 5009.88-2014 "Determination of Dietary Fiber in Food". Using the Folin-Ciocalteau reagent method, the content of dietary fiber-bound polyphenols increased from 15.71% to 45.10%. Physical methods were used to determine water-holding capacity and swelling capacity, showing an increase of 22-30% in water-holding capacity and 10-15% in swelling capacity. Using ABTS free radical scavenging kits, superoxide free radical scavenging kits, and hydroxyl free radical scavenging kits, the scavenging rates against ABTS free radicals, superoxide free radicals, and hydroxyl free radicals reached 83.54%, 79.16%, and 88.22%, respectively.

[0053] Example 2:

[0054] like Figure 1As shown, using waste bamboo shoot residue from the production and processing of bamboo shoots as raw material, the bamboo shoot residue was first dried in an oven at 70℃ until the moisture content was 9%. Then, it was placed in a pulverizer for preliminary pulverization to obtain coarse bamboo shoot residue powder. This coarse powder was then further refined using a planetary ball mill at a speed of 400 r / min for 4 hours, with a ball-to-size ratio of 1:3 and a ball-to-material mass ratio of 3:1. The average particle size of the bamboo shoot residue powder after planetary ball milling was 16.5 μm. In a sterile operating table, 0.35 g each of *Bacillus belye*, *Bacillus natto*, *Trichoderma koningii*, *Cladosporium*, *Aspergillus fowleri*, and *Bacillus coagulans* were weighed and added to conical centrifuge tubes containing 40 mL of MRS liquid culture medium. These were then activated by incubation in a shaker incubator at 36℃ and 255 rpm. Weigh 75g of the bamboo shoot residue powder obtained above, add pure water at a material-to-liquid mass ratio of 1:13, stir evenly, and sterilize at 121℃ for 15 minutes. Dispense the sterilized bamboo shoot residue homogenate into 5L fermentation tanks, seal the materials, and allow them to cool. This process is performed entirely on a sterile workbench. Adjust the pH of the bamboo shoot residue homogenate to 6.5, and add activated Bacillus belye, Bacillus natto, and Trichoderma koningii to form a compound inoculum solution (inoculum-to-liquid volume ratio: Bacillus belye: Bacillus natto: Trichoderma koningii = 1:1:3), with an inoculum size of 3%. This process is also performed entirely on a sterile workbench. Place the fermentation tank in a constant temperature and humidity incubator at 36℃ and 60% humidity for fermentation for 3 days. After this stage of fermentation, sterilize the bamboo shoot residue homogenate at 121℃ for 15 minutes. The bamboo shoot residue from the previous fermentation stage was homogenized and sterilized. The pH was adjusted to 6, and a compound inoculum solution composed of activated *Cladosporium oryzae*, *Aspergillus oryzae*, and *Bacillus coagulans* (volume ratio: *Aspergillus oryzae*: *Trichoderma reesei*: *Bacillus coagulans* = 1:1:3) was added at an inoculation rate of 3%. This entire process was performed on a sterile workbench. The fermentation tank was placed in a constant temperature and humidity incubator at 36℃ and 60% humidity for 6 days. After this stage of fermentation, the bamboo shoot residue homogenate was sterilized at 121℃ for 15 minutes. After modification, the bamboo shoot residue homogenate was removed, freeze-dried under vacuum, and the dietary fiber content was determined. The results showed that after modification with multi-strain coupled fermentation technology using bamboo shoot residue as raw material, the soluble dietary fiber content increased significantly from 8.74% to 34.76%, the insoluble dietary fiber content decreased significantly from 39.97% to 5.17%, and the dietary fiber-bound polyphenols increased from 15.49% to 47.88%. The water-holding capacity of the bamboo shoot residue powder increased by 22-30%, the swelling capacity increased by 10-15%, and the scavenging rates against ABTS free radicals, superoxide free radicals, and hydroxyl free radicals reached 88.75%, 81.55%, and 75.36%, respectively.

[0055] Example 3:

[0056] like Figure 1 As shown, using waste bamboo shoot residue from the production and processing of common edible bamboo shoots such as square bamboo shoots as raw material, the bamboo shoot residue was first dried in an oven at 80℃ until the moisture content was 8%. Then, it was placed in a pulverizer for preliminary pulverization to obtain coarse bamboo shoot residue powder. This coarse powder was then further refined using a planetary ball mill at a speed of 450 r / min for 5 hours, with a ball-to-material ratio of 1:5 for large to small balls and a ball-to-material mass ratio of 4:1. The average particle size of the bamboo shoot residue powder after planetary ball milling was 11.5 μm. In a sterile operating table, 0.5 g each of *Bacillus belye*, *Bacillus natto*, *Trichoderma koningii*, *Cladosporium*, *Aspergillus pumilus*, and *Bacillus coagulans* were weighed and added to conical centrifuge tubes containing 40 mL of MRS liquid culture medium. These were then activated by incubation in a shaker incubator at 37℃ and 270 rpm for 48 hours. Weigh 100g of the bamboo shoot residue powder obtained above, add pure water at a material-to-liquid mass ratio of 1:15, stir evenly, and sterilize at 121℃ for 15 minutes. Dispense the sterilized bamboo shoot residue homogenate into 5L fermentation tanks, seal the materials, and allow them to cool. This process is performed entirely on a sterile workbench. Adjust the pH of the bamboo shoot residue homogenate to 7.5, and add activated Bacillus belye, Bacillus natto, and Trichoderma koningii to form a compound inoculum solution (inoculum-to-liquid volume ratio: Bacillus belye: Bacillus natto: Trichoderma koningii = 1:1:5), with an inoculum size of 5%. This process is also performed entirely on a sterile workbench. Place the fermentation tank in a constant temperature and humidity incubator at 37℃ and 65% humidity for fermentation for 2 days. After this fermentation stage, sterilize the bamboo shoot residue homogenate at 121℃ for 15 minutes. The bamboo shoot residue from the previous fermentation stage was homogenized and sterilized. The pH was adjusted to 6.5, and a compound inoculum solution composed of activated Cladosporium, Aspergillus foetida, and Bacillus coagulans (in a volume ratio of Cladosporium: Aspergillus foetida: Bacillus coagulans = 1:1:5) was added at an inoculation rate of 5%. This entire process was performed on a sterile workbench. The fermentation tank was placed in a constant temperature and humidity incubator at 37°C and 65% humidity for 7 days. After this stage of fermentation, the bamboo shoot residue was homogenized and sterilized at 121°C for 15 minutes. After modification, the bamboo shoot residue homogenate was removed, freeze-dried under vacuum, and the dietary fiber content in the bamboo shoot residue was determined. The results showed that after modification with multi-strain coupled fermentation technology using bamboo shoot residue as raw material, the soluble dietary fiber content increased significantly from 7.68% to 35.91%, the insoluble dietary fiber content decreased significantly from 33.74% to 7.11%, and the dietary fiber-bound polyphenols increased from 15.51% to 42.08%. The water-holding capacity of the bamboo shoot residue powder increased by 22-30%, the swelling capacity increased by 10-15%, and the scavenging rates against ABTS free radicals, superoxide free radicals, and hydroxyl free radicals reached 89.03%, 80.94%, and 79.57%, respectively.

[0057] Finally, it should be noted that the above preferred embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail through the above preferred embodiments, those skilled in the art should understand that various changes can be made to it in form and detail without departing from the scope defined by the claims of the present invention.

Claims

1. A method for processing bamboo shoot residue to synergistically enhance the content of soluble dietary fiber and its bound polyphenols, characterized in that, The specific steps are as follows: (1) First, the waste bamboo shoot residue is dried, preliminarily crushed and ball-milled to obtain bamboo shoot residue powder; (2) Then, Bacillus berleis, Bacillus natto and Trichoderma kangsei were cultured and activated in a shaker and mixed to obtain the first compound bacterial culture solution; Cladosporium argentis, Aspergillus buergerianum and Bacillus coagulans were cultured and activated in a shaker and mixed to obtain the second compound bacterial culture solution. (3) Then mix the bamboo shoot residue powder with purified water, sterilize, adjust the pH to 5.5-7.5, inoculate with the first compound bacterial culture liquid, carry out the first stage of fermentation, and sterilize. (4) Adjust the pH to 5.5-6.5, inoculate with the second compound bacterial culture, carry out the second stage of fermentation, sterilize, and freeze dry under vacuum. In step (2), the first compound bacterial culture solution is prepared by the following method: Bacillus belye, Bacillus natto, and Trichoderma kangsei are first activated by shaking culture to obtain the corresponding bacterial culture solutions, and then mixed in a volume ratio of 1:1:2 to 5; the second compound bacterial culture solution is prepared by the following method: Cladosporium argentis, Aspergillus fowleri, and Bacillus coagulans are first activated by shaking culture to obtain the corresponding bacterial culture solutions, and then mixed in a volume ratio of 1:1:2 to 5. In step (3), the mass ratio of bamboo shoot residue powder to purified water is 1:10-15, and the volume inoculation amount of the first compound bacterial culture solution is 1-5%. In step (3), the process conditions for the first stage of fermentation are: temperature 35-37℃, humidity 55-65%, and fermentation time 2-4 days; In step (4), the volumetric inoculation amount of the second compound bacterial culture solution is 1-5%; The process conditions for the second stage of fermentation are: temperature 35-37℃, humidity 55-65%, and fermentation time 5-7 days; In step (1), the waste bamboo shoot residue includes, but is not limited to, the following edible bamboo shoot production and processing waste: moso bamboo shoots, hemp bamboo shoots, and square bamboo shoots; In step (1), the drying process conditions are: drying at 60-80℃ until the moisture content is 8-10 w.t.%; In step (1), a pulverizer is first used to perform preliminary pulverization to obtain coarse powder. Then, a planetary ball mill is used for ball milling. The speed of the ball mill is 300-450 r / min, the ball milling time is 3-5 hours, the ratio of large balls to small balls is 1:2-5, and the ball-to-material mass ratio is 2-4:

1. In step (2), Bacillus belye, Bacillus natto, Trichoderma koningii, Cladosporium cladosporium, Aspergillus pumilus, or Bacillus coagulans are inoculated into MRS liquid culture medium and cultured in a shaker for activation. The ratio of bacterial strain to MRS liquid culture medium is 0.25-0.5g:40mL. In step (2), the process conditions for shaking culture and activation are: temperature 35-37℃, rotation speed 240-270rpm, and culture time 24-48 hours.

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