A kind of grain arabinoxylan based on in vitro fecal bacteria fermentation directional bioconversion and its extraction method

Abstract

This invention discloses a method for the targeted biotransformation of cereal arabinoxylan based on in vitro fecal microbial fermentation and its extraction. The method includes: pulverizing and sieving cereal raw materials; extracting arabinoxylan from the cereal; using the extracted cereal arabinoxylan as a fermentation substrate and inoculating it into a fecal microbial fermentation system for anaerobic fermentation, utilizing intestinal microorganisms to target and degrade the arabinoxylan; terminating the anaerobic fermentation reaction; separating the fermentation broth into solid and liquid phases to obtain a supernatant containing the transformed product; purifying and drying the supernatant to obtain the final product. The product obtained by this invention is not only a highly active prebiotic, but it or the fermentation broth can also serve as a high-quality synbiotic (combined with probiotics) or postbiotic raw material, greatly expanding its application potential in functional foods, special medical foods, and health products.

Description

Technical Field

[0001] This invention belongs to the field of functional polysaccharide extraction technology, specifically relating to a cereal arabinoxylan based on in vitro fecal microbial fermentation and its extraction method. Background Technology

[0002] Currently, the main methods for extracting arabinoxylan from grains include water extraction, chemical solvent extraction, enzymatic extraction, and combinations of these methods. Water extraction is simple to operate but yields extremely low amounts. Chemical solvent extraction, especially alkaline extraction (such as using NaOH), while yielding higher amounts, suffers from strong alkaline conditions and high temperatures that damage the polysaccharide structure and introduce large amounts of salt ions, requiring complex desalting and purification steps and potentially impairing its biological activity. Enzymatic extraction (such as using xylanase) offers relatively mild conditions, but the extraction rate sometimes falls short of industrial-scale requirements. To obtain high-purity arabinoxylan for research, existing technologies have developed extremely complex multi-step purification processes. For example, the method disclosed in Chinese patent document CN106317260A includes multiple steps such as enzymatic hydrolysis, alkaline extraction, dialysis, alcohol precipitation, ion exchange cellulose, and gel chromatography. This process is lengthy, costly, and completely unsuitable for large-scale production. Another approach is to completely abandon extraction and adopt chemical synthesis methods, such as vacuum polymerization of arabinose and xylose under organic acid catalysis to prepare arabinoxylan. Although the method is relatively simplified, the product is a chemically synthesized polysaccharide whose structure is fundamentally different from that of naturally derived arabinoxylan, which has complex side chains and substituents, and its physiological functions may be different.

[0003] On the other hand, in vitro fecal fermentation technology is an important tool for evaluating the prebiotic potential of dietary fiber. Existing technologies (such as CN116287335B) have been used to assess the regulatory effects of arabinoxylan on the gut microbiota, judging its efficacy by measuring changes in short-chain fatty acid content, related enzyme activity, and bacterial abundance. However, this technology is currently only at the "post-evaluation" stage, that is, arabinoxylan is first extracted using traditional methods, and then used as a substrate for in vitro fermentation to evaluate its function. This separation between the "extraction" and "functional evaluation / enhancement" stages leads to current extraction processes always focusing on "yield" and "chemical purity" as core indicators, while neglecting the crucial biological functions of the final product, such as "prebiotic activity." It is impossible to actively and directionally produce arabinoxylan products with preset or enhanced functional characteristics during the extraction process.

[0004] Therefore, it is urgent to provide a method for the targeted preparation of arabinoxylan or its oligosaccharide products with enhanced prebiotic functions, using in vitro fecal microbial fermentation technology as the core biotransformation step. Summary of the Invention

[0005] The purpose of this section is to outline some aspects of embodiments of the present invention and to briefly describe some preferred embodiments. Simplifications or omissions may be made in this section, as well as in the abstract and title of this application, to avoid obscuring the purpose of these documents; however, such simplifications or omissions should not be construed as limiting the scope of the invention.

[0006] In view of the problems existing in the above and / or prior art, the present invention is proposed.

[0007] Therefore, the purpose of this invention is to overcome the shortcomings of the prior art and provide a method for the extraction of cereal arabinoxylan based on in vitro fecal microbial fermentation and directional biotransformation.

[0008] To solve the above-mentioned technical problems, the present invention provides the following technical solution: A method for extracting arabinoxylan from cereals based on directed biotransformation by in vitro fecal microbial fermentation includes the following steps: Crushing and sieving the cereal raw material to extract arabinoxylan from the cereal; Using the extract of arabinoxylan from the cereal as a fermentation substrate, inoculating it into a fecal microbial fermentation system for anaerobic fermentation, utilizing intestinal microorganisms to directionally degrade and transform arabinoxylan; Terminating the above anaerobic fermentation reaction, performing solid-liquid separation on the fermentation broth to obtain a supernatant containing the transformation product; Purifying and drying the supernatant to obtain the final product.

[0009] As a preferred embodiment of the preparation method of the present invention, the grain raw material includes one or more of wheat bran, barley bran, rye bran, highland barley bran, and corn bran; the extraction of arabinoxylan from the grain includes one of water extraction, alkali extraction, steam explosion-assisted extraction, and enzyme-assisted extraction.

[0010] As a preferred embodiment of the preparation method described in this invention, the enzyme preparation used in the enzyme-assisted extraction method includes one or more of pentosanase and cellulase.

[0011] As a preferred embodiment of the preparation method described in this invention, the fecal microbial fermentation system includes a microbial suspension prepared from healthy human feces, and a synthetic microbial community formulated with at least two probiotics from the genera Bifidobacterium, Lactobacillus, and Bacteroides.

[0012] As a preferred embodiment of the preparation method described in this invention, the anaerobic fermentation conditions are: fermentation temperature 35-39℃, pH 6.0-7.0, fermentation time 12-48 hours, and substrate concentration 1-5% (w / v).

[0013] As a preferred embodiment of the preparation method described in this invention, the fermentation is terminated by heating to 80-100°C and maintaining it for 10-20 minutes, and adjusting the pH to below 3.0 or above 9.0.

[0014] In a preferred embodiment of the preparation method described in this invention, the solid-liquid separation is centrifugal separation, with centrifugation conditions of 3000-5000 rpm for 10-20 minutes.

[0015] In a preferred embodiment of the preparation method described in this invention, the purification includes sequentially passing the supernatant through an ultrafiltration membrane with a molecular weight cutoff of 3000-5000 Da and a nanofiltration membrane with a molecular weight cutoff of 200-500 Da to separate arabinoxylose oligosaccharides of different molecular weight ranges and desalt them.

[0016] As a preferred embodiment of the preparation method described in this invention, the drying includes spray drying and vacuum freeze drying.

[0017] Another object of the present invention is to overcome the shortcomings of the prior art and provide an arabinoxylan conversion product, wherein the content of arabinoxylan oligosaccharides in the product accounts for more than 60% of the total sugar, and contains short-chain fatty acids and / or indole metabolites produced by intestinal microbial fermentation. Beneficial effects of this invention: (1) This invention integrates in vitro fecal microbial fermentation technology from an "efficacy evaluation tool" into a "core biotransformation and preparation process," realizing a paradigm shift from "passively extracting inherent components" to "actively manufacturing functional products." This is different from any existing simple extraction or chemical synthesis method, and also different from existing technologies that only use fermentation for evaluation.

[0018] (2) By selecting specific fermentation strains (such as a combination of probiotics with special metabolic capabilities for AX) and precisely controlling fermentation process parameters, this invention can guide intestinal microorganisms to specifically degrade arabinoxylan, thereby producing arabinoxylan oligosaccharides with specific polymerization degree that can efficiently promote the proliferation of target beneficial bacteria (such as Bifidobacterium and Lactobacillus), or producing a fermentation product system rich in beneficial metabolites such as short-chain fatty acids, thus realizing the "customization" of product functions.

[0019] (3) The entire process of this invention avoids the strong alkali (such as NaOH) and high temperature and long time treatment in the traditional alkali extraction method. It mainly relies on the mild hydrolysis of biological enzymes and the mild fermentation of microorganisms, which can maintain the natural structure and biological activity of arabinoxylan and its transformation products to the greatest extent.

[0020] (4) This invention integrates the traditional long process of "extraction, purification, and evaluation" into a compact process of "enrichment, biotransformation, and targeted membrane separation". By utilizing the specificity of biotransformation and the efficiency of membrane separation technology, it replaces the complex multi-step enzymatic hydrolysis, dialysis, column chromatography and other operations in traditional high-purity extraction methods, which significantly shortens the production cycle, reduces energy consumption and costs, and is easier to scale up.

[0021] (5) The product obtained by this invention is not only a highly active prebiotic, but it or the fermentation liquid can also be used as a high-quality synbiotic (combined with probiotics) or postbiotic raw material, which greatly expands the application potential in the fields of functional food, special medical food and health products. Attached Figure Description

[0022] To more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort. Wherein: Figure 1 This is a comparison of the effects of arabinoxylan products from different sources on the proliferation of Bifidobacterium adolescentis in Example 1 of the present invention. Figure 2 This invention illustrates the effects of different fermentation strains on the conversion efficiency and product function of arabinoxylan in various embodiments. Figure 3 The influence of key fermentation parameters on the conversion efficiency of arabinoxylan in embodiments of the present invention; Figure 4 This is a comparison of the sugar components in the products obtained by different extraction methods in the embodiments of the present invention. Detailed Implementation

[0023] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the specific embodiments of the present invention will be described in detail below with reference to the examples in the specification.

[0024] Many specific details are set forth in the following description in order to provide a full understanding of the invention. However, the invention may also be practiced in other ways different from those described herein, and those skilled in the art can make similar extensions without departing from the spirit of the invention. Therefore, the invention is not limited to the specific embodiments disclosed below.

[0025] Secondly, the term "one embodiment" or "embodiment" as used herein refers to a specific feature, structure, or characteristic that may be included in at least one implementation of the present invention. The phrase "in one embodiment" appearing in different places in this specification does not necessarily refer to the same embodiment, nor is it a single or selective embodiment that is mutually exclusive with other embodiments.

[0026] Unless otherwise specified, all raw materials used in the embodiments of this invention are commercially available. See Table 1 for details.

[0027] Table 1

[0028] The preparation process of the fecal microbiota suspension of this invention is as follows: Three volunteers who have not taken antibiotics in the past 6 months, have a healthy diet, and have no gastrointestinal diseases were selected, and their fresh fecal samples were collected. 1g of mixed feces was added to 10mL of sterile phosphate-buffered saline (PBS), and the mixture was thoroughly mixed under anaerobic conditions. The mixture was then filtered through 4 layers of sterile gauze. The filtrate is the intestinal microbiota seed solution, which was placed on ice or stored at 4°C for short-term use.

[0029] Simulated intestinal culture medium: 10g tryptone, 2g yeast extract, 2g phospholipids, 0.5g bile salts, 0.1g NaCl, 0.04g KH2PO4, 0.01g MgSO4·7H2O, 0.01g CaCl2·6H2O, 0.5g L-cysteine ​​(salt), 0.05g heme, 2g NaHCO3, 0.01g sazalin, 2mL Tween 80, 10μL / 0.01g vitamin K1, dissolved in 1L deionized water to prepare an alkaline culture medium. After adjusting the pH to 7.0, it was autoclaved at 121℃ for 20 minutes and then cooled.

[0030] Determination of arabinoxylo-oligosaccharide (AXOS, degree of polymerization 2-10): High performance liquid chromatography (HPLC) is used to separate sugar molecules with different degrees of polymerization by utilizing their different retention times in the chromatographic column. Qualitative analysis is performed by comparing the retention time with that of standards, and quantitative analysis is performed by peak area. The percentage of arabinoxylo-oligosaccharide in the target product is calculated.

[0031] The yield of arabinoxyl oligosaccharides (AXOS, DP 2-10) was determined by high performance liquid chromatography (HPLC).

[0032] Evaluation of prebiotic activity (proliferation-promoting effect): In vitro microbial culture method, using Bifidobacterium adolescentis (… Bifidobacteriumadolescentis The bacteria, identified as indicator bacteria, were anaerobically cultured in a culture medium containing the product of this invention. The optical density (OD) of the bacterial culture at a wavelength of 600 nm was measured after a certain period of cultivation. 600 The growth rate of the product was used to quantitatively evaluate its ability to promote the proliferation of the probiotic. The effectiveness was assessed by comparing it with a blank control (without a carbon source) and traditional alkali-extracted arabinoxylan.

[0033] In the experimental group, 1 mL of mixed fecal suspension was added to 9 mL of culture medium containing 100 mg of gastrointestinal digestive fluid and mixed thoroughly. In the blank control group, 100 mL of deionized water was added to the culture medium instead of the gastrointestinal digestive fluid.

[0034] Prebiotic activity index: based on the product's effect on Bifidobacterium adolescentis (… Bifidobacterium adolescentis ) and Lactobacillus reuteri ( Lactobacillus reuteri The in vitro proliferative capacity of ) (in terms of OD) 600 The growth rate of the value is used as the core evaluation indicator.

[0035] Total production of short-chain fatty acids (SCFA): The total amount of acetic acid, propionic acid and butyric acid in the fermentation supernatant was determined by gas chromatography.

[0036] Example 1 A method for extracting cereal arabinoxylan based on in vitro fecal microbial fermentation and directed biotransformation, the specific steps of which are as follows: S1. Raw material enrichment: Take 100g of wheat bran and crush it through a 60-mesh sieve. Add 1000mL of deionized water and extract by stirring in a water bath at 60℃ for 2 hours. Centrifuge (4000rpm, 15min) to collect the supernatant, and concentrate it under reduced pressure at 60℃ to a volume of 200mL to obtain a crude extract rich in water-soluble arabinoxylan (WEAX).

[0037] S2. In vitro fecal microbial fermentation: Fecal microbial suspensions were prepared from the feces of healthy volunteers. In an anaerobic workstation, the crude extract obtained in S1 was used as the sole carbon source (substrate concentration adjusted to 2% w / v), mixed with a simulated intestinal culture medium, and inoculated with 10% (v / v) of the fecal microbial suspension. Anaerobic fermentation was carried out at 37°C and pH 6.8 for 24 hours.

[0038] S3. Termination and Separation: After fermentation, place the fermentation flask in a 95°C water bath for 15 minutes to terminate the reaction. After cooling, centrifuge at 4°C and 5000 rpm for 20 minutes and collect the supernatant.

[0039] S4. Product purification: The supernatant is first passed through an ultrafiltration membrane with a molecular weight cutoff of 5000 Da, and the permeate is collected. The permeate is then passed through a nanofiltration membrane with a molecular weight cutoff of 300 Da for desalination and concentration. Finally, the nanofiltration concentrate is spray-dried (inlet air temperature 180℃, outlet air temperature 90℃) to obtain approximately 8.5g of a pale yellow powder product.

[0040] Example 2 A method for extracting cereal arabinoxylan based on in vitro fecal microbial fermentation and directed biotransformation, the specific steps of which are as follows: S1. Raw material enrichment: Take 100g of highland barley bran and pretreat it using steam explosion (pressure 0.8MPa, pressure maintained for 160s). After explosion, add 1000mL of pH 7.0 phosphate buffer and a compound enzyme (xylanase and cellulase in a 1:1 ratio, total enzyme amount 1% w / w), and enzymatically hydrolyze at 55℃ for 4 hours. After inactivating the enzyme in a boiling water bath for 10 minutes, centrifuge and concentrate the supernatant to 200mL.

[0041] S2. In vitro fecal microbial fermentation: A synthetic microbial community composed of Bifidobacterium bifidum and Lactobacillus plantarum in a 1:1 ratio was used. The S1 concentrate (3% w / v substrate concentration) was mixed with the culture medium, and 5% (v / v) of the synthetic microbial community was inoculated. Anaerobic fermentation was carried out at 37°C and pH 6.8 for 24 hours.

[0042] S3. Termination and Separation: Adjust the pH of the fermentation broth to 2.5 with 1M HCl to terminate the reaction. Then adjust the pH back to 7.0 with 1M NaOH, centrifuge (4000 rpm, 15 min), and collect the supernatant.

[0043] S4. Product purification: The supernatant was subjected to ultrafiltration (MWCO 3000 Da) and nanofiltration (MWCO 200 Da) sequentially. The nanofiltration concentrate was then freeze-dried under vacuum to obtain approximately 12.1 g of white flocculent product.

[0044] Example 3: Detection of arabinoxylose content Sample pretreatment: Take 5g of the final powder products prepared in Examples 1 and 2 respectively, dissolve them in ultrapure water or buffer solution, and remove insoluble impurities by dilution and filtration (0.22μm microporous membrane).

[0045] Chromatographic conditions: Use an HPLC system equipped with a refractive index detector (RID) or an evaporative light scattering detector (ELSD). The column is typically an amino column (NH2) or a column specifically designed for sugar analysis (such as the Bio-Rad Aminex HPX-87P), and the column temperature is maintained at a specific temperature (80°C). The mobile phase is ultrapure water or an acetonitrile-water mixture, using isocratic or gradient elution.

[0046] Sample loading and analysis: Inject the prepared sample solution into the chromatograph and run the program.

[0047] Qualitative and quantitative analysis: The retention times of each peak in the sample chromatogram are compared with the retention times of arabinoxyl oligosaccharide standards (xylobiose to xylodecanose) to identify each component. The percentage of the sum of the areas of the target peaks (degree of polymerization 2-10) to the sum of the areas of the total sugar peaks (all detectable sugar peaks) is calculated.

[0048] According to the test results, the content of arabinoxyl oligosaccharide (degree of polymerization 2-10) in Example 1 accounted for 75.68% of the total sugar, and the mass fractions of acetic acid, propionic acid and butyric acid in Example 2 were 60%, 20% and 20%, respectively.

[0049] Comparative Example 1: Traditional Alkali Extraction Method Referring to existing technology, 100g of the same wheat bran was extracted with 1M NaOH solution at 90℃ for 2 hours. After neutralization, centrifugation was performed, the supernatant was precipitated with alcohol, the precipitate was reconstituted with water, dialyzed to desalt, and finally freeze-dried. Approximately 9.8g of product was obtained, but subsequent testing revealed that its molecular weight was relatively large, and its in vitro antimicrobial activity was lower than that of the product in Example 1.

[0050] like Figure 4 As shown, the horizontal axis represents two different products, and the vertical axis represents relative content. This figure clearly illustrates the differences in composition between products obtained by different extraction methods, demonstrating that the product of this invention is superior to traditional alkali-extracted products in terms of obtaining highly active ingredients and improving product purity.

[0051] Example 4: Evaluation of Prebiotic Activity Bacterial strains and culture: reviving and activating Bifidobacterium adolescentis (Bifidobacterium adolescentis) Bifidobacteriumadolescentis ( ) as indicator probiotics.

[0052] Experimental groups: The experimental group (Example 1), the positive control group (Comparative Example 1, which uses arabinoxylan obtained by traditional alkali extraction as an equal amount of carbon source), and the blank control group (no carbon source) were set up.

[0053] Culture and Measurement: *Bifidobacterium adolescentis* in the logarithmic growth phase was inoculated into the above culture medium at a rate of 2%, v / v, and anaerobically cultured at 37°C for 24 hours. At the beginning (0h) and end of the culture, samples were taken to measure the optical density (OD600) of the bacterial culture at a wavelength of 600 nm. 00 ).

[0054] like Figure 1 As shown, the horizontal axis represents different experimental groups, and the vertical axis represents the OD value within 36 hours. 600 Increase in OD value 600 , ΔOD 600 (36 hours). This figure clearly shows the significant differences in the promoting effects of arabinoxylan products from different sources on the proliferation of Bifidobacterium longum. The product of this invention shows a superior effect on promoting the proliferation of Bifidobacterium longum compared to traditional alkali-extracted products, while the blank control group showed almost no promoting effect. This indicates that the product of this invention has a significantly better promoting effect on the proliferation of Bifidobacterium longum than traditional alkali-extracted products.

[0055] Results analysis: Calculation of OD for each group 600 The growth rate (endpoint OD value - starting OD value). In vitro prebiotic experiments showed that this product had a significantly better proliferative effect on Bifidobacterium adolescentis than an equal amount of traditionally extracted arabinoxylan. Experimental group OD 600The growth rate was significantly higher than that of the positive control group, which directly proves that the product prepared by the method of this invention has better activity in promoting the proliferation of specific probiotics (i.e., prebiotic activity) than products prepared by traditional methods.

[0056] Comparative Example 2: Complex Purification Method Referring to Chinese patent CN106317260A, a multi-step enzymatic hydrolysis, alkaline extraction, dialysis, alcohol precipitation, and DE-32 and S-400 column chromatography method was used to extract arabinoxylan from highland barley. This yielded a high-purity product, but the entire process took more than a week, was cumbersome, and had a yield of approximately 13.8%, making it completely unsuitable for large-scale production.

[0057] Example 4 The difference from Example 1 is that the fermentation strain treatment group is different in step S2. Fermentation is carried out under the same conditions (37°C, pH 6.8, 24h). The remaining steps are the same as in Example 1. The specific settings are shown in Table 2.

[0058] Table 2

[0059] As shown in Table 2, the fecal microbiota suspension from healthy humans (Example 1) exhibited the most balanced and superior performance, with the highest AXOS yield and SCFA production, and a strong effect on promoting the proliferation of both probiotics. This demonstrates that co-fermentation using a complete and healthy gut microbiota can simulate the complex metabolic network in vivo, achieving comprehensive and efficient conversion of AX and generating diverse beneficial products.

[0060] The specific probiotic combination (Example 2) showed the strongest targeted growth-promoting effect on Bifidobacterium adolescentis, demonstrating potential for functional customization. Although the yield of SCFA was slightly lower, its products have unique value in the development of prebiotic products targeting specific strains.

[0061] The transformation efficiency and functional product diversity of single bacterial species are significantly lower than those of complex bacterial communities, proving that the metabolic capacity of a single strain is limited and cannot replace the synergistic effect of multiple bacterial species.

[0062] like Figure 2 As shown, the horizontal axis represents different fermentation sources. The left-hand Y-axis represents the yield (%) of AX oligosaccharides (AXOS) and the Bifidobacterium Proliferation Activity (ΔOD). 600The right-hand Y-axis represents the total short-chain fatty acid (SCFA) production (mM). This figure clearly demonstrates the significant differences in xylan conversion efficiency and product function among different fermentation sources. It illustrates that human fecal microbiota suspensions from healthy donors and combinations of synthetic probiotics are preferred fermentation sources, while single-species or sterilized microbiota are less suitable for this purpose. The extremely low negative control data excludes interference from non-biotransformation factors, confirming that the conversion is driven by microbial activity.

[0063] Example 5 The difference from Example 1 is that the fermentation temperature in step S2 is different, and the specific settings are shown in Table 3. The remaining steps are the same as in Example 1.

[0064] Table 3

[0065] As shown in Table 3, the microbial community maintains optimal activity and balance, and the transformation efficiency is highest when the temperature is between 35-39℃ (especially 37℃). Outside this range, the activity decreases significantly.

[0066] Example 6 The difference from Example 1 is that the fermentation time in step S2 is different, and the specific settings are shown in Table 4. The remaining steps are the same as in Example 1.

[0067] Table 4

[0068] As shown in Table 4, effective conversion can be achieved within 12-48 hours of fermentation. 12-24 hours is the optimal window for efficiency and activity. Too short a time will result in insufficient conversion, while too long a time may lead to excessive degradation and is uneconomical.

[0069] Example 7 The difference from Example 1 is that the fermentation pH is different in step S2, and the specific settings are shown in Table 5. The remaining steps are the same as in Example 1.

[0070] Table 5

[0071] Table 5 shows that pH 6.0-7.0 is the suitable range for maintaining the stability and efficient metabolism of complex fecal microbiota; exceeding this range will significantly affect the microbiota structure and transformation function. Figure 3As shown, the x-axis of subplot (A) represents fermentation temperature (°C); the x-axis of subplot (B) represents fermentation time (h); and the x-axis of subplot (C) represents initial pH. The y-axis of all three subplots represents the yield (%) of arabinoxylan oligosaccharides (AXOS). This figure illustrates that by controlling the fermentation temperature at approximately 39°C, the fermentation time at least 24 hours, and the initial pH at approximately 6.8, the conversion efficiency of arabinoxylan can be maximized.

[0072] The comparison between the above embodiments and comparative examples shows that the method provided by the present invention not only has a high degree of process integration and mild conditions, but also can produce highly active prebiotic products in a targeted manner, and has significant advantages in terms of yield, functionality and industrial feasibility.

[0073] It should be noted that the above 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 with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention, and all such modifications or substitutions should be covered within the scope of the present invention.

Claims

1. A method for the extraction of cereal arabinoxylan based on the in vitro fecal bacteria fermentation directed biotransformation, characterized by: Includes the following steps: The grain raw material is crushed and sieved to extract arabinoxylan from the grain. The extract of arabinoxylan from the grain is used as a fermentation substrate and inoculated into a fecal microbial fermentation system for anaerobic fermentation, utilizing intestinal microorganisms to perform targeted degradation and transformation of arabinoxylan. The above anaerobic fermentation reaction is terminated, and the fermentation broth is subjected to solid-liquid separation to obtain a supernatant containing the transformation product. The supernatant is purified and dried to obtain the final product.

2. The method according to claim 1, c h a r a c t e r i z e d in that: The grain raw materials include one or more of wheat bran, barley bran, rye bran, highland barley bran, and corn bran; the extraction of arabinoxylan from the grains includes one of water extraction, alkali extraction, steam explosion-assisted extraction, and enzyme-assisted extraction.

3. The method according to claim 2, c h a r a c t e r i z e d in that: The enzyme preparations used in the enzyme-assisted extraction method include one or more of pentosanase and cellulase.

4. The method of claim 1, wherein: The fecal microbial fermentation system includes a microbial suspension prepared from the feces of healthy humans, and a synthetic microbial community formulated with at least two probiotics from the genera Bifidobacterium, Lactobacillus, and Bacteroides.

5. The method for extracting arabinoxylan from grains according to claim 4, characterized in that: The anaerobic fermentation conditions are: fermentation temperature 35-39℃, pH 6.0-7.0, fermentation time 12-48 hours, and substrate concentration 1-5% (w / v).

6. The method for extracting arabinoxylan from grains according to claim 1, characterized in that: Methods to terminate fermentation include heating to 80-100℃ and maintaining it for 10-20 minutes, or adjusting the pH to below 3.0 or above 9.

0.

7. The method according to claim 1, characterized in that: The solid-liquid separation is centrifugal separation, with centrifugation conditions of 3000-5000 rpm for 10-20 minutes.

8. The method according to claim 1, characterized in that: The purification process involves sequentially passing the supernatant through an ultrafiltration membrane with a molecular weight cutoff of 3000-5000 Da and a nanofiltration membrane with a molecular weight cutoff of 200-500 Da to separate and desalt arabinoxylose oligosaccharides of different molecular weight ranges.

9. The method according to claim 1 or 8, characterized in that: The drying process includes spray drying and vacuum freeze drying.

10. An arabinoxylan conversion product prepared by the method according to any one of claims 1-9, characterized in that: The product contains more than 60% arabinoxylose as the total sugar content, and also contains short-chain fatty acids and / or indole metabolites produced by intestinal microorganism fermentation.

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