A method for extracting pentosan from wheat bran by combining irradiation and microbial fermentation

Abstract

The present invention provides a method for extracting pentosan from wheat bran by irradiation-microorganism fermentation. Wheat bran is crushed and electron beam irradiated to obtain irradiated wheat bran powder. The irradiated wheat bran powder is stirred and mixed with water. Wheat bran fermentation liquid is obtained by mixed fermentation of Saccharomyces boulardii and Bacillus subtilis. The wheat bran fermentation liquid is subjected to freeze-thaw centrifugation, alcohol extraction filtration, and freeze drying to obtain pentosan. In the present invention, electron beam irradiation can penetrate and bombard chemical bonds in the cell wall of wheat bran through high-energy electron beams, causing them to break, degrading cellulose and hemicellulose contained in the cell wall, destroying the tight connection between wheat bran cell wall fibers, promoting material outflow, laying a good fermentation foundation for subsequent microbial fermentation, and improving fermentation efficiency. At the same time, mixed fermentation of Saccharomyces boulardii and Bacillus subtilis utilizes substrates to produce abundant enzyme systems and metabolites, further improving the content and quality of pentosan.

Description

Technical Field

[0001] The invention belongs to the technical field of polysaccharide preparation, and particularly relates to a method for extracting pentosan from wheat bran by combining irradiation and microbial fermentation. Background Art

[0002] Wheat bran is the main by-product of wheat processing into flour. It is rich in protein, dietary fiber, multiple vitamins and minerals, and physiologically active ingredients. Dietary fiber helps improve the intestinal environment, promote the growth of beneficial bacteria, maintain intestinal health, and can also lower cholesterol, inhibit fat absorption, prevent arteriosclerosis, anti-oxidation, antibacterial, anti-tumor, and regulate immunity. Protein is easily digested and absorbed by the body, can lower blood lipid concentration, prevent cardiovascular disease, and help improve liver function and prevent the occurrence of hepatic encephalopathy. Although the annual output of wheat bran is high, its deep processing and utilization is low. It is currently mainly used in the preparation of livestock and poultry feed, brewing, soy sauce fermentation, etc., resulting in a great waste of bioactive substances in wheat bran.

[0003] Pentosan, also known as arabinoxylan, is the main component of wheat bran cell wall polysaccharide, accounting for about 20% of the dry basis of wheat bran. Its monomers include arabinose and xylose. Pentosan has a variety of excellent biological activities, such as regulating gastrointestinal flora, promoting the reproduction of probiotics such as bifidobacteria and lactobacilli in the intestine, lowering blood sugar, improving immunity and anti-tumor, etc. With its special physical and chemical properties and functional characteristics, pentosan can be used in many food fields such as pasta, beverages, and wine. However, there are few studies on the deep processing of pentosan into food. Currently, there are only pentosan beverages, pentosan nutritional powders and other related products on the market. The form is relatively simple, and the flavor and taste of the products cannot be generally accepted by consumers. This is mainly because the preparation process of pentosan includes crude extraction and separation and purification of pentosan. The existing extraction methods include physical methods, chemical methods, and biological methods. Separation and purification mainly remove impurities in crude pentosan extracts, such as starch, protein, etc., all of which have various defects, resulting in the pentosan prepared by the existing method not being able to meet the requirements of large-scale production in the market.

[0004] Physical methods for extracting pentosans include hydrothermal extraction, ultrasonic extraction, microwave extraction, steam explosion, etc. Among them, hydrothermal extraction requires the use of heat-resistant equipment, the prepared pentosans are dark in color, the subsequent purification process is complicated, and the yield is low. Ultrasonic extraction uses the cavitation effect to separate wheat bran, but long-term ultrasonic treatment will cause the molecular chain of pentosan to disintegrate, reducing the quality and extraction rate. Excessive microwave treatment will cause pentosan degradation. The high temperature and high pressure environment provided by steam explosion will promote the occurrence of Maillard reaction, leading to the formation of browning substances, reducing the extraction rate of total pentosans, and there are problems such as incomplete degradation of the corresponding substrate, harsh conditions and high cost. Chemical methods for pentosan extraction include acid hydrolysis and alkali extraction. The acid hydrolysis method is too violent and will degrade pentosan into furfural substances. There are many side reaction products, which reduce the yield of pentosan. The corrosiveness of strong acid can easily damage the production equipment and the quality of pentosan. Alkaline extraction mainly uses hydroxide ions to destroy the chemical bonds between macromolecular polymers in the cell wall, but there are problems such as long extraction time, large consumption of alkali, difficult alkaline wastewater treatment and easy environmental pollution. The biological method for pentosan extraction is mainly based on enzymatic hydrolysis. The corresponding enzyme can act on the specific chemical bonds in the structure of macromolecular substances in the cell wall of wheat bran, thereby decomposing it into small molecules. The reaction conditions are relatively mild, there are fewer by-products, and subsequent purification is more convenient. However, in the process of preparing pentosan by enzymatic method, a variety of enzymes such as amylase, cellulase, and proteinase are added, which will increase the enzyme inactivation link, resulting in a longer extraction process time and increasing the cost of enzyme use.

[0005] Therefore, it is urgent to invent a method for extracting pentosan from wheat bran by combining irradiation and microbial fermentation, which can not only reduce the production cost of pentosan extraction, but also shorten the reaction time and increase the yield of pentosan. At the same time, the reaction process is easy to control and convenient for large-scale industrial production, providing theoretical support for further in-depth research on the efficient extraction of pentosan. Summary of the invention

[0006] Technical problems to be solved: In view of the above technical problems, the purpose of the present invention is to provide a method for extracting pentosan from wheat bran by irradiation-microorganism fermentation. Wheat bran is crushed and irradiated with electron beam to obtain irradiated wheat bran powder. The irradiated wheat bran powder is stirred and mixed with water, and wheat bran fermentation liquid is obtained by mixed fermentation with Saccharomyces boulardii and Bacillus subtilis. The wheat bran fermentation liquid is subjected to freeze-thaw centrifugation, alcohol extraction filtration, and freeze-drying to obtain pentosan. Electron beam irradiation can penetrate and bombard the chemical bonds in the cell wall of wheat bran through high-energy electron beams, causing them to break, degrading cellulose and hemicellulose contained in the cell wall, destroying the tight connection between the fibers of the wheat bran cell wall, promoting the outflow of substances, laying a good fermentation foundation for subsequent microbial fermentation, and improving the fermentation efficiency. At the same time, the mixed fermentation of Saccharomyces boulardii and Bacillus subtilis utilizes the substrate to produce rich enzyme systems and metabolites, further improving the content and quality of pentosan.

[0007] Technical solution: A method for extracting pentosan from wheat bran by combining irradiation and microbial fermentation, comprising the following steps: S1. crushing wheat bran through a 50-80 mesh sieve, putting it into a sealed bag, and irradiating it to obtain irradiated wheat bran powder; S2. adding water to the irradiated wheat bran powder in a mass ratio of 1:(2-6) and stirring and mixing, and then adding 1-7wt.% magnesium gluconate to obtain an irradiated wheat bran solution;

[0008] S3. After the activation of Saccharomyces boulardii and Bacillus subtilis, the mixed bacterial solution is inoculated into the irradiated wheat bran solution for fermentation to obtain wheat bran fermentation liquid;

[0009] S4. The wheat bran fermentation liquid is subjected to freeze-thaw centrifugation cycles, and then subjected to alcohol extraction, filtration, and freeze-drying to obtain pentosan.

[0010] Furthermore, the irradiation dose at the irradiation site in step S1 is 1-35 kGy.

[0011] Furthermore, the activation method of Saccharomyces boulardii in step S3 is: thawing the frozen Saccharomyces boulardii, inoculating it into a sterilized YPD solid culture medium, streaking and culturing it at 30° C., picking colonies with an inoculation loop and inoculating them into a sterilized YPD liquid culture medium and placing it in a shaker, culturing it at 30° C. and 120-180 rpm for 24 hours, and obtaining an activated Saccharomyces boulardii liquid.

[0012] Furthermore, the activation method of Bacillus subtilis in step S3 is: thawing the frozen Bacillus subtilis and inoculating it into a sterilized LB solid culture medium, culturing it at 37° C. for 24 hours, then picking colonies with an inoculation loop and inoculating them into a sterilized LB liquid culture medium, culturing it at 37° C. and 120-180 rpm for 24 hours, to obtain an activated Bacillus subtilis bacterial solution.

[0013] Furthermore, the amount of the mixed bacterial solution added in step S3 is 2-10%, and the ratio of Saccharomyces boulardii to Bacillus subtilis is (2:1)-(1:3).

[0014] Furthermore, in step S3, the fermentation temperature is 25-37° C., and the fermentation time is 1-7 days.

[0015] Furthermore, the freezing temperature of the repeated freeze-thaw centrifugation in step S4 is (-30)-(-18)°C, the freezing time is 1-3h, the thawing temperature is 25-40°C, the number of freeze-thaw cycles is 2-5 times, the centrifugal speed is 3000-4000r / min, and the centrifugal time is 10-20min. Furthermore, the alcohol extraction method in step S4 is to add 95% ethanol in a volume ratio of 1:(2-4) to the supernatant after centrifugation and let it stand at 2-6°C for 2-4h.

[0016] Beneficial effects:

[0017] 1. The electron beam irradiation used in the present invention can produce high-energy electron beam excitation irradiation and bombardment, destroy the tightly connected chemical bonds in the components such as cellulose, hemicellulose, lignin, etc. in the wheat bran cell wall, cause the degradation of related substances in the wheat bran cell wall, lead to the disintegration of the cell wall structure or the formation of holes, thereby destroying the integrity of the wheat bran cell wall, which is beneficial to the efficient utilization of microbial fermentation, and can also reduce the content of anti-nutritional factors such as phytic acid in wheat bran, so that the nutrients in the fermentation matrix are easier to be absorbed and utilized by microorganisms, creating a fermentation environment that is more suitable for reproduction and metabolism for microbial fermentation.

[0018] 2. In the present invention, Saccharomyces boulardii and Bacillus subtilis are mixed for fermentation. The protease, amylase, xylanase, pentosanase and the like produced by the two can not only further destroy the cell wall of wheat bran, and make pentosan more easily released, but also synergistically decompose complex macromolecules such as protein and starch in irradiated wheat bran into pentosans, and degrade longer fragments of insoluble pentosans, thereby increasing the solubility of pentosans, which is beneficial to the subsequent extraction and separation process. Moreover, the metabolites such as amino acids, organic acids and fatty acids produced by Saccharomyces boulardii can assist and promote the metabolic decomposition of Bacillus subtilis, thereby extracting pentosans more efficiently.

[0019] 3. The magnesium gluconate added in the present invention can be provided as a nutrient to Saccharomyces boulardii and Bacillus subtilis, support the growth and metabolic activities of microorganisms, and can help regulate and stabilize the pH value of the wheat bran fermentation liquid, create a suitable growth environment, and at the same time induce substances such as polypeptides in the fermentation system to combine to form a stable complex through hydrophobic interaction or hydrogen bonding, and further promote the complex complexation, agglutination and precipitation during the freeze-thaw process during repeated freezing and thawing, which is convenient for subsequent centrifugal removal.

[0020] 4. The method for extracting pentosans from wheat bran by combining irradiation and microbial fermentation provided by the present invention not only broadens the extraction pathways of pentosans from wheat bran and fully promotes the development and utilization rate of wheat bran, but also can effectively improve the economic added value of wheat bran, and provides theoretical support for the development and utilization of pentosans in the food industry, which has important practical significance and broad application prospects. DETAILED DESCRIPTION

[0021] The present invention will be further described below in conjunction with embodiments, which are explanations of the present invention and are not limited to the following embodiments:

[0022] The strains used in the present invention are: Saccharomyces boulardii JLCG13542, purchased from Jiangxi Jianglan Pure Biological Reagent Co., Ltd.; Bacillus subtilis CICC24603, purchased from China Industrial Microbiological Culture Collection Management Center.

[0023] Example 1

[0024] A method for extracting pentosan from wheat bran by combining irradiation and microbial fermentation, comprising the following steps:

[0025] S1. 500 g of wheat bran was crushed through an 80-mesh sieve, placed in a sealed bag, and irradiated at an electron beam irradiation dose of 25 kGy to obtain irradiated wheat bran powder;

[0026] S2. Weigh 300g of irradiated wheat bran powder and add 1200g of water, stir and mix, then add 75g of magnesium gluconate to obtain an irradiated wheat bran solution;

[0027] S3. After activation of Saccharomyces boulardii JLCG13542 and Bacillus subtilis CICC24603, 126 g of mixed bacterial solution (84 g of Saccharomyces boulardii JLCG13542 bacterial solution and 42 g of Bacillus subtilis CICC24603 bacterial solution) was inoculated into the irradiated wheat bran solution and fermented at 30°C for 5 days to obtain wheat bran fermentation solution;

[0028] S4. The wheat bran fermentation liquid was frozen at -25°C for 2 hours, thawed at 30°C, centrifuged at 3500r / min for 15 minutes to obtain the supernatant, and the freeze-thaw and centrifugation cycles were repeated 3 times. Then, 4 times 95% ethanol was added and the mixture was allowed to stand at 4°C for 4 hours, filtered, and freeze-dried to obtain pentosan.

[0029] Example 2

[0030] A method for extracting pentosan from wheat bran by combining irradiation and microbial fermentation, comprising the following steps:

[0031] S1. 500g of wheat bran was crushed through a 50-mesh sieve, placed in a sealed bag, and irradiated at an electron beam irradiation dose of 5kGy to obtain irradiated wheat bran powder;

[0032] S2. Weigh 250g of irradiated wheat bran powder and add 1000g of water, stir and mix, then add 62.5g of magnesium gluconate to obtain an irradiated wheat bran solution;

[0033] S3. After activation of Saccharomyces boulardii JLCG13542 and Bacillus subtilis CICC24603, 105 g of mixed bacterial solution (70 g of Saccharomyces boulardii JLCG13542 bacterial solution and 35 g of Bacillus subtilis CICC24603 bacterial solution) was inoculated into the irradiated wheat bran solution and fermented at 30°C for 5 days to obtain wheat bran fermentation solution;

[0034] S4. The wheat bran fermentation liquid was frozen at -22°C for 2.5 hours, thawed at 25°C, centrifuged at 3000 r / min for 20 minutes to obtain the supernatant, and the freeze-thaw cycle was repeated twice. Then, 4 times 95% ethanol was added, allowed to stand at 4°C for 4 hours, and then filtered. After freeze-drying, pentosan was obtained.

[0035] Example 3

[0036] A method for extracting pentosan from wheat bran by combining irradiation and microbial fermentation, comprising the following steps:

[0037] S1. 500 g of wheat bran was crushed through a 60-mesh sieve, placed in a sealed bag, and irradiated at an electron beam irradiation dose of 10 kGy to obtain irradiated wheat bran powder;

[0038] S2. Weigh 100g of irradiated wheat bran powder and add 400g of water, stir and mix, then add 25g of magnesium gluconate to obtain an irradiated wheat bran solution;

[0039] S3. After activation of Saccharomyces boulardii JLCG13542 and Bacillus subtilis CICC24603, 42 g of mixed bacterial solution (28 g of Saccharomyces boulardii JLCG13542 bacterial solution and 14 g of Bacillus subtilis CICC24603 bacterial solution) was inoculated into the irradiated wheat bran solution and fermented at 30° C. for 5 days to obtain wheat bran fermentation solution;

[0040] S4. The wheat bran fermentation liquid was frozen at -20°C for 1.5 hours, thawed at 35°C, centrifuged at 4000r / min for 10 minutes to obtain the supernatant, and the freeze-thaw and centrifugation cycles were repeated 4 times. Then, 4 times 95% ethanol was added, allowed to stand at 4°C for 4 hours, filtered, and freeze-dried to obtain pentosan.

[0041] Example 4

[0042] A method for extracting pentosan from wheat bran by combining irradiation and microbial fermentation, comprising the following steps:

[0043] S1. 500 g of wheat bran was crushed through an 80-mesh sieve, placed in a sealed bag, and irradiated at an electron beam dose of 15 kGy to obtain irradiated wheat bran powder;

[0044] S2. Weigh 300g of irradiated wheat bran powder and add 1200g of water, stir and mix, then add 75g of magnesium gluconate to obtain an irradiated wheat bran solution;

[0045] S3. After activation of Saccharomyces boulardii JLCG13542 and Bacillus subtilis CICC24603, 126 g of mixed bacterial solution (84 g of Saccharomyces boulardii JLCG13542 bacterial solution and 42 g of Bacillus subtilis CICC24603 bacterial solution) was inoculated into the irradiated wheat bran solution and fermented at 30°C for 5 days to obtain wheat bran fermentation solution;

[0046] S4. The wheat bran fermentation liquid was frozen at -26°C for 1 hour, thawed at 40°C, centrifuged at 3500r / min for 15 minutes to obtain the supernatant, and the freeze-thaw and centrifugation cycles were repeated 5 times. Then, 4 times 95% ethanol was added and the mixture was allowed to stand at 4°C for 4 hours, filtered, and freeze-dried to obtain pentosan.

[0047] Example 5

[0048] A method for extracting pentosan from wheat bran by combining irradiation and microbial fermentation, comprising the following steps:

[0049] S1. 500 g of wheat bran was crushed through an 80-mesh sieve, placed in a sealed bag, and irradiated at an electron beam irradiation dose of 20 kGy to obtain irradiated wheat bran powder;

[0050] S2. Weigh 200g of irradiated wheat bran powder and add 800g of water, stir and mix, then add 50g of magnesium gluconate to obtain an irradiated wheat bran solution;

[0051] S3. After activation of Saccharomyces boulardii JLCG13542 and Bacillus subtilis CICC24603, 84 g of mixed bacterial solution (56 g of Saccharomyces boulardii JLCG13542 bacterial solution and 28 g of Bacillus subtilis CICC24603 bacterial solution) was inoculated into the irradiated wheat bran solution and fermented at 30° C. for 5 days to obtain wheat bran fermentation solution;

[0052] S4. The wheat bran fermentation liquid was frozen at -27°C for 3 hours, thawed at 35°C, centrifuged at 4000r / min for 20 minutes to obtain the supernatant, and the freeze-thaw and centrifugation cycles were repeated 3 times. Then, 4 times 95% ethanol was added and the mixture was allowed to stand at 4°C for 4 hours, filtered, and freeze-dried to obtain pentosan.

[0053] Example 6

[0054] A method for extracting pentosan from wheat bran by combining irradiation and microbial fermentation, comprising the following steps:

[0055] S1. 500g of wheat bran was crushed through a 60-mesh sieve, placed in a sealed bag, and irradiated at an electron beam irradiation dose of 30kGy to obtain irradiated wheat bran powder;

[0056] S2. Weigh 350g of irradiated wheat bran powder and add 1400g of water, stir and mix, then add 87.5g of magnesium gluconate to obtain an irradiated wheat bran solution;

[0057] S3. After activation of Saccharomyces boulardii JLCG13542 and Bacillus subtilis CICC24603, 147 g of mixed bacterial solution (78 g of Saccharomyces boulardii JLCG13542 bacterial solution and 39 g of Bacillus subtilis CICC24603 bacterial solution) was inoculated into the irradiated wheat bran solution and fermented at 30° C. for 5 days to obtain wheat bran fermentation solution;

[0058] S4. The wheat bran fermentation liquid was frozen at -21°C for 2 hours, thawed at 25°C, centrifuged at 3500r / min for 15 minutes to obtain the supernatant, and the freeze-thaw and centrifugation cycles were repeated 4 times. Then, 4 times 95% ethanol was added and the mixture was allowed to stand at 4°C for 4 hours, filtered, and freeze-dried to obtain pentosan.

[0059] Performance Testing

[0060] (1) Pentosan yield

[0061] The calculation formula of pentosan yield is: Where m1 is the mass of pentosan, g; m2 is the mass of wheat bran, g.

[0062] (2) Water-soluble pentosan content

[0063] The water-soluble pentosan was determined by the phloroglucinol-glacial acetic acid method. 1.0 g of pentosan sample was accurately weighed and placed in a stoppered colorimetric tube. 2 mL of distilled water was added, followed by 10 mL of color developer. Distilled water was used as a blank control. The colorimetric tube was placed in a violently boiling water bath for 25 minutes, then rapidly cooled under water flow, and the absorbance at 552 nm and 510 nm was measured. Calculation formula: The equation of D-xylose standard curve is y=0.6949x-0.0314(R 2 =0.9988), C is the D-xylose concentration calculated by the D-xylose standard curve equation, mg / mL; V is the volume of the pentosan solution to be tested, mL; 0.88 is the ratio coefficient of water-soluble pentosan to xylose; m is the mass of the pentosan sample, g.

[0064] (3) Ferulic acid content

[0065] Accurately weigh 0.5 g of pentosan sample, add 24 mL of 2 mol / L NaOH solution, blow with nitrogen for 1 min and seal, stir with a magnetic stirrer for 20 min at room temperature, add 6 mol / L hydrochloric acid solution to adjust the pH to 2, extract with an equal volume of ethyl acetate solution for 4 times, combine the supernatants, and use a vacuum rotary evaporator to evaporate to dryness at 45 °C, make up to 10 mL with methanol, and store in a -20 °C refrigerator.

[0066] Liquid phase detection conditions: chromatographic column Waters Symmetry C18 column (250×4.6 mm; 5 μm), mobile phase prepared from acetonitrile and 1% glacial acetic acid, flow rate 1.0 mL / min, column temperature 40°C, detection wavelength 320 nm, injection volume 10 μL, all samples were filtered with 0.45 μm filter membrane before injection.

[0067] Elution procedure: 0-4min, the volume fraction of glacial acetic acid in the mobile phase decreased from 79% to 77%, 4-8min, the volume fraction of glacial acetic acid in the mobile phase decreased from 77% to 60%, 8-11min, the volume fraction of glacial acetic acid in the mobile phase decreased from 60% to 0%, and 11-21min, the volume fraction of glacial acetic acid in the mobile phase increased from 0%B to 79%.

[0068] Table 1 Pentosan yield, water-soluble pentosan content and ferulic acid content of Examples 1-6

[0069]

[0070] As can be seen from Table 1, in Examples 1-6, as the irradiation dose of wheat bran irradiation treatment increases, the pentosan yield, water-soluble pentosan content and ferulic acid content all show a trend of first increasing and then decreasing, indicating that the irradiation dose deviates from the optimal value, resulting in incomplete fragmentation of the cell wall structure in the wheat bran, and insufficient cleavage of the chemical bonds between cellulose, hemicellulose and lignin, thereby increasing the difficulty of Saccharomyces boulardii and Bacillus subtilis in utilizing the fermentation substrate in the fermentation step, resulting in lower pentosan yield, water-soluble pentosan content and ferulic acid content.

[0071] Example 7

[0072] A method for extracting pentosan from wheat bran by combining irradiation and microbial fermentation, comprising the following steps:

[0073] S1. 500 g of wheat bran was crushed through an 80-mesh sieve, placed in a sealed bag, and irradiated at an electron beam irradiation dose of 25 kGy to obtain irradiated wheat bran powder;

[0074] S2. Weigh 250g of irradiated wheat bran powder and add 1000g of water, stir and mix, then add 12.5g of magnesium gluconate to obtain an irradiated wheat bran solution;

[0075] S3. After the activation of Saccharomyces boulardii JLCG13542 and Bacillus subtilis CICC24603, 101 g of mixed bacterial solution (67 g of Saccharomyces boulardii JLCG13542 bacterial solution and 34 g of Bacillus subtilis CICC24603 bacterial solution) was inoculated into the irradiated wheat bran solution and fermented at 30° C. for 5 days to obtain wheat bran fermentation solution;

[0076] S4. The wheat bran fermentation liquid was frozen at -19°C for 2.5 hours, thawed at 35°C, centrifuged at 3000 r / min for 10 minutes to obtain the supernatant, and the freeze-thaw and centrifugation cycles were repeated 5 times. After that, 4 times 95% ethanol was added and the liquid was allowed to stand at 4°C for 4 hours, filtered, and freeze-dried to obtain pentosan.

[0077] Example 8

[0078] A method for extracting pentosan from wheat bran by combining irradiation and microbial fermentation, comprising the following steps:

[0079] S1. 500 g of wheat bran was crushed through a 60-mesh sieve, placed in a sealed bag, and irradiated at an electron beam irradiation dose of 25 kGy to obtain irradiated wheat bran powder;

[0080] S2. Weigh 150g of irradiated wheat bran powder and add 600g of water, stir and mix, then add 22.5g of magnesium gluconate to obtain an irradiated wheat bran solution;

[0081] S3. After the activation of Saccharomyces boulardii JLCG13542 and Bacillus subtilis CICC24603, 61.8 g of mixed bacterial solution (41.2 g of Saccharomyces boulardii JLCG13542 bacterial solution and 20.6 g of Bacillus subtilis CICC24603 bacterial solution) was inoculated into the irradiated wheat bran solution and fermented at 30°C for 5 days to obtain wheat bran fermentation solution;

[0082] S4. The wheat bran fermentation liquid was frozen at -20°C for 2 hours, thawed at 30°C, centrifuged at 4000r / min for 20 minutes to obtain the supernatant, and the freeze-thaw and centrifugation cycles were repeated twice. Then, 4 times 95% ethanol was added, allowed to stand at 4°C for 4 hours, and then filtered. After freeze-drying, pentosan was obtained.

[0083] Example 9

[0084] A method for extracting pentosan from wheat bran by combining irradiation and microbial fermentation, comprising the following steps:

[0085] S1. 500 g of wheat bran was crushed through an 80-mesh sieve, placed in a sealed bag, and irradiated at an electron beam irradiation dose of 25 kGy to obtain irradiated wheat bran powder;

[0086] S2. Weigh 300g of irradiated wheat bran powder and add 1200g of water, stir and mix, then add 105g of magnesium gluconate to obtain an irradiated wheat bran solution;

[0087] S3. After the activation of Saccharomyces boulardii JLCG13542 and Bacillus subtilis CICC24603, 128.4 g of mixed bacterial solution (85.6 g of Saccharomyces boulardii JLCG13542 bacterial solution and 42.8 g of Bacillus subtilis CICC24603 bacterial solution) was inoculated into the irradiated wheat bran solution and fermented at 30° C. for 5 days to obtain wheat bran fermentation solution;

[0088] S4. The wheat bran fermentation liquid was frozen at -25°C for 3 hours, thawed at 25°C, centrifuged at 3500r / min for 20 minutes to obtain the supernatant, and the freeze-thaw and centrifugation cycles were repeated 3 times. Then, 4 times 95% ethanol was added and the mixture was allowed to stand at 4°C for 4 hours, filtered, and freeze-dried to obtain pentosan.

[0089] Table 2 Pentosan yield, water-soluble pentosan content and ferulic acid content of Example 1 and Examples 7-9

[0090]

[0091]

[0092] As can be seen from Table 2, as the amount of magnesium gluconate added increases, the pentosan yield, water-soluble pentosan content and ferulic acid content of Example 1 and Examples 7-9 all show a trend of first increasing and then decreasing, indicating that too little magnesium gluconate is added, resulting in it being utilized by Saccharomyces boulardii and Bacillus subtilis during the fermentation process, and cannot be chelated with polypeptides, reducing sugars and other substances produced by metabolism to form a precipitate to be removed during freeze-thaw centrifugation, increasing the probability of impurities in pentosan and reducing the quality of pentosan.

[0093] Example 10

[0094] A method for extracting pentosan from wheat bran by combining irradiation and microbial fermentation, comprising the following steps:

[0095] S1. 500 g of wheat bran was crushed through an 80-mesh sieve, placed in a sealed bag, and irradiated at an electron beam irradiation dose of 25 kGy to obtain irradiated wheat bran powder;

[0096] S2. Weigh 250g of irradiated wheat bran powder and add 1000g of water, stir and mix, then add 62.5g of magnesium gluconate to obtain an irradiated wheat bran solution;

[0097] S3. After activation of Saccharomyces boulardii JLCG13542 and Bacillus subtilis CICC24603, 26.25 g of mixed bacterial solution (17.5 g of Saccharomyces boulardii JLCG13542 bacterial solution and 8.75 g of Bacillus subtilis CICC24603 bacterial solution) was inoculated into the irradiated wheat bran solution and fermented at 30°C for 5 days to obtain wheat bran fermentation solution;

[0098] S4. The wheat bran fermentation liquid was frozen at -24°C for 1 hour, thawed at 35°C, centrifuged at 3000r / min for 15 minutes to obtain the supernatant, and the freeze-thaw and centrifugation cycles were repeated 5 times. Then, 4 times 95% ethanol was added and the mixture was allowed to stand at 4°C for 4 hours, filtered, and freeze-dried to obtain pentosan.

[0099] Embodiment 11

[0100] A method for extracting pentosan from wheat bran by combining irradiation and microbial fermentation, comprising the following steps:

[0101] S1. 500 g of wheat bran was crushed through a 70-mesh sieve, placed in a sealed bag, and irradiated at an electron beam irradiation dose of 25 kGy to obtain irradiated wheat bran powder;

[0102] S2. Weigh 100g of irradiated wheat bran powder and add 400g of water, stir and mix, then add 25g of magnesium gluconate to obtain an irradiated wheat bran solution;

[0103] S3. After the activation of Saccharomyces boulardii JLCG13542 and Bacillus subtilis CICC24603, 21 g of mixed bacterial solution (14 g of Saccharomyces boulardii JLCG13542 bacterial solution and 7 g of Bacillus subtilis CICC24603 bacterial solution) was inoculated into the irradiated wheat bran solution and fermented at 30°C for 5 days to obtain wheat bran fermentation solution;

[0104] S4. The wheat bran fermentation liquid was frozen at -28°C for 1 hour, thawed at 30°C, centrifuged at 4000r / min for 10 minutes to obtain the supernatant, and the freeze-thaw and centrifugation cycles were repeated 4 times. Then, 4 times 95% ethanol was added and the mixture was allowed to stand at 4°C for 4 hours, filtered, and freeze-dried to obtain pentosan.

[0105] Example 12

[0106] A method for extracting pentosan from wheat bran by combining irradiation and microbial fermentation, comprising the following steps:

[0107] S1. 500 g of wheat bran was crushed through an 80-mesh sieve, placed in a sealed bag, and irradiated at an electron beam irradiation dose of 25 kGy to obtain irradiated wheat bran powder;

[0108] S2. Weigh 200g of irradiated wheat bran powder and add 800g of water, stir and mix, then add 50g of magnesium gluconate to obtain an irradiated wheat bran solution;

[0109] S3. After activation of Saccharomyces boulardii JLCG13542 and Bacillus subtilis CICC24603, 63 g of mixed bacterial solution (42 g of Saccharomyces boulardii JLCG13542 bacterial solution and 21 g of Bacillus subtilis CICC24603 bacterial solution) was inoculated into the irradiated wheat bran solution and fermented at 30° C. for 5 days to obtain wheat bran fermentation solution;

[0110] S4. The wheat bran fermentation liquid was frozen at -30°C for 1.5 hours, thawed at 35°C, centrifuged at 3500r / min for 10 minutes to obtain the supernatant, and the freeze-thaw and centrifugation cycles were repeated 4 times. Then, 4 times 95% ethanol was added, allowed to stand at 4°C for 4 hours, and then filtered. After freeze-drying, pentosan was obtained.

[0111] Embodiment 13

[0112] A method for extracting pentosan from wheat bran by combining irradiation and microbial fermentation, comprising the following steps:

[0113] S1. 500 g of wheat bran was crushed through a 70-mesh sieve, placed in a sealed bag, and irradiated at an electron beam irradiation dose of 25 kGy to obtain irradiated wheat bran powder;

[0114] S2. Weigh 300g of irradiated wheat bran powder and add 1200g of water, stir and mix, then add 75g of magnesium gluconate to obtain an irradiated wheat bran solution;

[0115] S3. After activation of Saccharomyces boulardii JLCG13542 and Bacillus subtilis CICC24603, 157.5 g of mixed bacterial solution (105 g of Saccharomyces boulardii JLCG13542 bacterial solution and 52.5 g of Bacillus subtilis CICC24603 bacterial solution) was inoculated into the irradiated wheat bran solution and fermented at 30°C for 5 days to obtain wheat bran fermentation solution;

[0116] S4. The wheat bran fermentation liquid was frozen at -18°C for 3 hours, thawed at 40°C, centrifuged at 3000r / min for 15 minutes to obtain the supernatant, and the freeze-thaw and centrifugation cycles were repeated 3 times. Then, 4 times 95% ethanol was added and the mixture was allowed to stand at 4°C for 4 hours, filtered, and freeze-dried to obtain pentosan.

[0117] Embodiment 14

[0118] A method for extracting pentosan from wheat bran by combining irradiation and microbial fermentation, comprising the following steps:

[0119] S1. 500 g of wheat bran was crushed through an 80-mesh sieve, placed in a sealed bag, and irradiated at an electron beam irradiation dose of 25 kGy to obtain irradiated wheat bran powder;

[0120] S2. Weigh 100g of irradiated wheat bran powder and add 400g of water, stir and mix, then add 25g of magnesium gluconate to obtain an irradiated wheat bran solution;

[0121] S3. After the activation of Saccharomyces boulardii JLCG13542 and Bacillus subtilis CICC24603, 42 g of mixed bacterial solution (21 g of Saccharomyces boulardii JLCG13542 bacterial solution and 21 g of Bacillus subtilis CICC24603 bacterial solution) was inoculated into the irradiated wheat bran solution and fermented at 30° C. for 5 days to obtain wheat bran fermentation solution;

[0122] S4. The wheat bran fermentation liquid was frozen at -20°C for 2 hours, thawed at 35°C, centrifuged at 3500r / min for 15 minutes to obtain the supernatant, and the freeze-thaw and centrifugation cycles were repeated 5 times. Then, 4 times 95% ethanol was added and the mixture was allowed to stand at 4°C for 4 hours, filtered, and freeze-dried to obtain pentosan.

[0123] Embodiment 15

[0124] A method for extracting pentosan from wheat bran by combining irradiation and microbial fermentation, comprising the following steps:

[0125] S1. 500 g of wheat bran was crushed through a 60-mesh sieve, placed in a sealed bag, and irradiated at an electron beam irradiation dose of 25 kGy to obtain irradiated wheat bran powder;

[0126] S2. Weigh 200g of irradiated wheat bran powder and add 800g of water, stir and mix, then add 50g of magnesium gluconate to obtain an irradiated wheat bran solution;

[0127] S3. After activation of Saccharomyces boulardii JLCG13542 and Bacillus subtilis CICC24603, 84 g of mixed bacterial solution (28 g of Saccharomyces boulardii JLCG13542 bacterial solution and 56 g of Bacillus subtilis CICC24603 bacterial solution) was inoculated into the irradiated wheat bran solution and fermented at 30° C. for 5 days to obtain wheat bran fermentation solution;

[0128] S4. The wheat bran fermentation liquid was frozen at -25°C for 2.5 hours, thawed at 20°C, centrifuged at 4000r / min for 10 minutes to obtain the supernatant, and the freeze-thaw cycle was repeated twice. Then, 4 times 95% ethanol was added, and the mixture was allowed to stand at 4°C for 4 hours, filtered, and freeze-dried to obtain pentosan.

[0129] Table 3 Pentosan yield, water-soluble pentosan content and ferulic acid content of Example 1 and Examples 10-15

[0130]

[0131] As can be seen from Table 3, in Examples 1 and 10-15, with the increase of the inoculation amount of the mixed bacterial solution and the different colony ratios, the pentosan yield, water-soluble pentosan content and ferulic acid content all showed a trend of first increasing and then decreasing, indicating that the amount of strain added was too little, and Saccharomyces boulardii and Bacillus subtilis failed to fully utilize the fermentation substrate, resulting in a decrease in the amount of pentosan produced, and the inoculation amount of the mixed bacterial solution was too much, Saccharomyces boulardii and Bacillus subtilis would utilize the pentosan in the fermentation substrate, thereby reducing the pentosan content; in the strain ratio, Saccharomyces boulardii would ferment to produce metabolites utilized by Bacillus subtilis, but a high ratio of Bacillus subtilis would produce competitive metabolism, and insufficient metabolites would be available, thereby inhibiting the fermentation process and reducing the fermentation efficiency.

[0132] Example 16

[0133] A method for extracting pentosan from wheat bran by combining irradiation and microbial fermentation, comprising the following steps:

[0134] S1. 500 g of wheat bran was crushed through a 60-mesh sieve, placed in a sealed bag, and irradiated at an electron beam irradiation dose of 25 kGy to obtain irradiated wheat bran powder;

[0135] S2. Weigh 250g of irradiated wheat bran powder and add 1000g of water, stir and mix, then add 62.5g of magnesium gluconate to obtain an irradiated wheat bran solution;

[0136] S3. After activation of Saccharomyces boulardii JLCG13542 and Bacillus subtilis CICC24603, 105 g of mixed bacterial solution (70 g of Saccharomyces boulardii JLCG13542 bacterial solution and 35 g of Bacillus subtilis CICC24603 bacterial solution) was inoculated into the irradiated wheat bran solution and fermented at 25° C. for 5 days to obtain wheat bran fermentation solution;

[0137] S4. The wheat bran fermentation liquid was frozen at -21°C for 2 hours, thawed at 25°C, centrifuged at 3000r / min for 20 minutes to obtain the supernatant, and the freeze-thaw and centrifugation cycles were repeated 3 times. Then, 4 times 95% ethanol was added and the mixture was allowed to stand at 4°C for 4 hours, filtered, and freeze-dried to obtain pentosan.

[0138] Embodiment 17

[0139] A method for extracting pentosan from wheat bran by combining irradiation and microbial fermentation, comprising the following steps:

[0140] S1. 500 g of wheat bran was crushed through an 80-mesh sieve, placed in a sealed bag, and irradiated at an electron beam irradiation dose of 25 kGy to obtain irradiated wheat bran powder;

[0141] S2. Weigh 150g of irradiated wheat bran powder and add 600g of water, stir and mix, then add 37.5g of magnesium gluconate to obtain an irradiated wheat bran solution;

[0142] S3. After activation of Saccharomyces boulardii JLCG13542 and Bacillus subtilis CICC24603, 63 g of mixed bacterial solution (42 g of Saccharomyces boulardii JLCG13542 bacterial solution and 21 g of Bacillus subtilis CICC24603 bacterial solution) was inoculated into the irradiated wheat bran solution and fermented at 35° C. for 5 days to obtain wheat bran fermentation solution;

[0143] S4. The wheat bran fermentation liquid was frozen at -26°C for 2 hours, thawed at 35°C, centrifuged at 4000r / min for 15 minutes to obtain the supernatant, and the freeze-thaw and centrifugation cycles were repeated 4 times. Then, 4 times 95% ethanol was added, allowed to stand at 4°C for 4 hours, and then filtered. After freeze-drying, pentosan was obtained.

[0144] Embodiment 18

[0145] A method for extracting pentosan from wheat bran by combining irradiation and microbial fermentation, comprising the following steps:

[0146] S1. 500 g of wheat bran was crushed through a 70-mesh sieve, placed in a sealed bag, and irradiated at an electron beam irradiation dose of 25 kGy to obtain irradiated wheat bran powder;

[0147] S2. Weigh 300g of irradiated wheat bran powder and add 1200g of water, stir and mix, then add 75g of magnesium gluconate to obtain an irradiated wheat bran solution;

[0148] S3. After the activation of Saccharomyces boulardii JLCG13542 and Bacillus subtilis CICC24603, 126 g of mixed bacterial solution (84 g of Saccharomyces boulardii JLCG13542 bacterial solution and 42 g of Bacillus subtilis CICC24603 bacterial solution) was inoculated into the irradiated wheat bran solution and fermented at 30° C. for 1 day to obtain wheat bran fermentation solution;

[0149] S4. The wheat bran fermentation liquid was frozen at -25°C for 2 hours, thawed at 40°C, centrifuged at 3500r / min for 15 minutes to obtain the supernatant, and the freeze-thaw and centrifugation cycles were repeated 4 times. Then, 4 times 95% ethanol was added and the mixture was allowed to stand at 4°C for 4 hours, filtered, and freeze-dried to obtain pentosan.

[0150] Embodiment 19

[0151] A method for extracting pentosan from wheat bran by combining irradiation and microbial fermentation, comprising the following steps:

[0152] S1. 500 g of wheat bran was crushed through an 80-mesh sieve, placed in a sealed bag, and irradiated at an electron beam irradiation dose of 25 kGy to obtain irradiated wheat bran powder;

[0153] S2. Weigh 250g of irradiated wheat bran powder and add 1000g of water, stir and mix, then add 62.5g of magnesium gluconate to obtain an irradiated wheat bran solution;

[0154] S3. After the activation of Saccharomyces boulardii JLCG13542 and Bacillus subtilis CICC24603, 105 g of mixed bacterial solution (70 g of Saccharomyces boulardii JLCG13542 bacterial solution and 35 g of Bacillus subtilis CICC24603 bacterial solution) was inoculated into the irradiated wheat bran solution and fermented at 30° C. for 3 days to obtain wheat bran fermentation solution;

[0155] S4. The wheat bran fermentation liquid was frozen at -30°C for 3 hours, thawed at 30°C, centrifuged at 3000r / min for 20 minutes to obtain the supernatant, and the freeze-thaw and centrifugation cycles were repeated 3 times. Then, 4 times 95% ethanol was added and the mixture was allowed to stand at 4°C for 4 hours, filtered, and freeze-dried to obtain pentosan.

[0156] Embodiment 20

[0157] A method for extracting pentosan from wheat bran by combining irradiation and microbial fermentation, comprising the following steps:

[0158] S1. 500 g of wheat bran was crushed through an 80-mesh sieve, placed in a sealed bag, and irradiated at an electron beam irradiation dose of 25 kGy to obtain irradiated wheat bran powder;

[0159] S2. Weigh 100g of irradiated wheat bran powder and add 400g of water, stir and mix, then add 25g of magnesium gluconate to obtain an irradiated wheat bran solution;

[0160] S3. After the activation of Saccharomyces boulardii JLCG13542 and Bacillus subtilis CICC24603, 42 g of mixed bacterial solution (28 g of Saccharomyces boulardii JLCG13542 bacterial solution and 14 g of Bacillus subtilis CICC24603 bacterial solution) was inoculated into the irradiated wheat bran solution and fermented at 30° C. for 7 days to obtain wheat bran fermentation solution;

[0161] S4. The wheat bran fermentation liquid was frozen at -23°C for 1.5 hours, thawed at 35°C, centrifuged at 3500r / min for 10 minutes to obtain the supernatant, and the freeze-thaw and centrifugation cycles were repeated 4 times. Then, 4 times 95% ethanol was added, allowed to stand at 4°C for 4 hours, filtered, and freeze-dried to obtain pentosan.

[0162] Table 4 Pentosan yield, water-soluble pentosan content and ferulic acid content of Example 1 and Examples 16-20

[0163]

[0164] As can be seen from Table 4, with the increase of fermentation temperature and the extension of fermentation time, the pentosan yield, water-soluble pentosan content and ferulic acid content of Example 1 and Examples 16-20 all showed a trend of first increasing and then decreasing, indicating that the fermentation temperature and fermentation time deviating from the optimal range will affect the process of mixed fermentation of Saccharomyces boulardii and Bacillus subtilis, further reduce the fermentation efficiency, and thus affect the conversion of the substances in the fermentation matrix into pentosan by the two.

[0165] Comparative Example 1

[0166] This comparative example differs from Example 1 in that no electron beam irradiation was used.

[0167] A method for extracting pentosans from wheat bran by microbial fermentation comprises the following steps:

[0168] S1. 500 g of wheat bran was crushed through an 80-mesh sieve to obtain wheat bran powder;

[0169] S2. Weigh 300g of wheat bran powder and add 1200g of water, stir and mix, then add 75g of magnesium gluconate to obtain an irradiated wheat bran solution;

[0170] S3. After activation of Saccharomyces boulardii JLCG13542 and Bacillus subtilis CICC24603, 126 g of mixed bacterial solution (84 g of Saccharomyces boulardii JLCG13542 bacterial solution and 42 g of Bacillus subtilis CICC24603 bacterial solution) was inoculated into the irradiated wheat bran solution and fermented at 30°C for 5 days to obtain wheat bran fermentation solution;

[0171] S4. The wheat bran fermentation liquid was frozen at -25°C for 2 hours, thawed at 30°C, centrifuged at 3500r / min for 15 minutes to obtain the supernatant, and the freeze-thaw and centrifugation cycles were repeated 3 times. Then, 4 times 95% ethanol was added and the mixture was allowed to stand at 4°C for 4 hours, filtered, and freeze-dried to obtain pentosan.

[0172] Comparative Example 2

[0173] The difference between this comparative example and Example 1 is that the Saccharomyces boulardii JLCG13542 bacterial solution in the mixed bacterial solution is replaced by Bacillus subtilis CICC24603 bacterial solution.

[0174] A method for extracting pentosans from wheat bran by fermenting with Bacillus subtilis comprises the following steps:

[0175] S1. 500 g of wheat bran was crushed through an 80-mesh sieve, placed in a sealed bag, and irradiated at an electron beam irradiation dose of 25 kGy to obtain irradiated wheat bran powder;

[0176] S2. Weigh 300g of irradiated wheat bran powder and add 1200g of water, stir and mix, then add 75g of magnesium gluconate to obtain an irradiated wheat bran solution;

[0177] S3. After activation of Bacillus subtilis CICC24603, 126 g of Bacillus subtilis CICC24603 bacterial solution was inoculated into the irradiated wheat bran solution and fermented at 30° C. for 5 days to obtain wheat bran fermentation liquid;

[0178] S4. The wheat bran fermentation liquid was frozen at -25°C for 2 hours, thawed at 30°C, centrifuged at 3500r / min for 15 minutes to obtain the supernatant, and the freeze-thaw and centrifugation cycles were repeated 3 times. Then, 4 times 95% ethanol was added and the mixture was allowed to stand at 4°C for 4 hours, filtered, and freeze-dried to obtain pentosan.

[0179] Comparative Example 3

[0180] The difference between this comparative example and Example 1 is that the Bacillus subtilis CICC24603 bacterial solution in the mixed bacterial solution is replaced by Saccharomyces boulardii JLCG13542 bacterial solution.

[0181] A method for extracting pentosans from wheat bran by fermenting Saccharomyces boulardii comprises the following steps:

[0182] S1. 500 g of wheat bran was crushed through an 80-mesh sieve, placed in a sealed bag, and irradiated at an electron beam irradiation dose of 25 kGy to obtain irradiated wheat bran powder;

[0183] S2. Weigh 300g of irradiated wheat bran powder and add 1200g of water, stir and mix, then add 75g of magnesium gluconate to obtain an irradiated wheat bran solution;

[0184] S3. After Saccharomyces boulardii JLCG13542, 126 g of Saccharomyces boulardii JLCG13542 bacterial solution was inoculated into the irradiated wheat bran solution, and fermented at 30° C. for 5 days to obtain wheat bran fermentation liquid;

[0185] S4. The wheat bran fermentation liquid was frozen at -25°C for 2 hours, thawed at 30°C, centrifuged at 3500r / min for 15 minutes to obtain the supernatant, and the freeze-thaw and centrifugation cycles were repeated 3 times. Then, 4 times 95% ethanol was added and the mixture was allowed to stand at 4°C for 4 hours, filtered, and freeze-dried to obtain pentosan.

[0186] Comparative Example 4

[0187] The present invention is different from Example 1 in that magnesium gluconate is not added.

[0188] A method for extracting pentosan from wheat bran by combining irradiation and microbial fermentation, comprising the following steps:

[0189] S1. 500 g of wheat bran was crushed through an 80-mesh sieve, placed in a sealed bag, and irradiated at an electron beam irradiation dose of 25 kGy to obtain irradiated wheat bran powder;

[0190] S2. Weigh 300g of irradiated wheat bran powder and add 1200g of water and stir to mix to obtain an irradiated wheat bran solution;

[0191] S3. After activation of Saccharomyces boulardii JLCG13542 and Bacillus subtilis CICC24603, 120 g of mixed bacterial solution (80 g of Saccharomyces boulardii JLCG13542 bacterial solution and 40 g of Bacillus subtilis CICC24603 bacterial solution) was inoculated into the irradiated wheat bran solution and fermented at 30°C for 5 days to obtain wheat bran fermentation solution;

[0192] S4. The wheat bran fermentation liquid was frozen at -25°C for 2 hours, thawed at 30°C, centrifuged at 3500r / min for 15 minutes to obtain the supernatant, and the freeze-thaw and centrifugation cycles were repeated 3 times. Then, 4 times 95% ethanol was added and the mixture was allowed to stand at 4°C for 4 hours, filtered, and freeze-dried to obtain pentosan.

[0193] Performance Testing

[0194] (1) Particle size

[0195] The laser light scattering method was used for determination. An appropriate amount of the pentosan samples of Example 1 and Comparative Examples 1-4 were weighed, dissolved in distilled water to prepare a solution with a concentration of 0.2-0.5 mg / mL, and filtered through a 0.45 μm filter membrane for later use. The solution was analyzed and determined using a dynamic laser light scattering instrument. The measurement conditions were: the medium was an aqueous solution, the scanning angle was 90°, the temperature was 25°C, the wavelength was 532 nm, and the scanning time was 300 s.

[0196] (2) Solubility

[0197] Accurately weigh 2.00 g of the pentosan samples of Example 1 and Comparative Examples 1-4, prepare a 1% (w / v) solution with deionized water, let stand in a water bath at 30°C for 30 min, then centrifuge at 4000 r / min for 10 min, take the supernatant, dry in an oven at 120°C to constant weight, record the final weight W1, and calculate the solubility:

[0198] Table 5 Pentosan yield, water-soluble pentosan content, ferulic acid content, solubility and particle size of Example 1 and Comparative Examples 1-4

[0199]

[0200] As shown in Table 5, the pentosan yield, water-soluble pentosan content, ferulic acid content, solubility and particle size of Example 1 are all higher than those of Comparative Examples 1-4, indicating that electron beam irradiation can destroy the tightly connected chemical bonds in components such as cellulose, hemicellulose, and lignin in the wheat bran cell wall, causing the degradation of related substances in the wheat bran cell wall, which is beneficial to the mixed fermentation of Saccharomyces boulardii and Bacillus subtilis. The rich enzymes produced by the mixed fermentation can further destroy the cell wall, promote the dissolution of pentosan, and convert the fermented starch into pentosan, thereby increasing the pentosan content. In addition, the addition of magnesium gluconate can chelate polypeptides and non-pentosan components to form a stable complex, which is removed in the form of precipitation during the freeze-thaw process.

[0201] The above is only a preferred embodiment of the present invention and does not limit the present invention in any form. Any technician familiar with the art can make many possible changes and modifications to the technical solution of the present invention by using the above disclosed methods and technical contents without departing from the spirit and technical solution of the present invention, or modify it into an equivalent embodiment of equivalent changes. Therefore, any simple modification, equivalent replacement, equivalent change and modification made to the above embodiments according to the technical essence of the present invention without departing from the content of the technical solution of the present invention still falls within the scope of protection of the technical solution of the present invention.

Claims

1. A method for extracting pentosans from wheat bran by combining irradiation and microbial fermentation, characterized in that: The following steps are involved: S1. The wheat bran is crushed through a 50-80 mesh sieve, placed in a sealed bag, and irradiated to obtain irradiated wheat bran powder; the irradiation dose of the irradiation treatment is 1-35kGy; S2. Add water to the irradiated wheat bran powder in a mass ratio of 1:(2-6) and stir to mix, then add 1-7wt% magnesium gluconate to prepare an irradiated wheat bran solution; S3. After the activation of Saccharomyces boulardii and Bacillus subtilis, the mixed bacterial solution is inoculated into the irradiated wheat bran solution for fermentation to obtain wheat bran fermentation solution; the amount of the mixed bacterial solution added is 2-10%, and the ratio of Saccharomyces boulardii to Bacillus subtilis is (2:1)-(1:3); the fermentation temperature is 25-37°C, and the fermentation time is 1-7 days; S4. The wheat bran fermentation liquid is subjected to freeze-thaw centrifugation cycles, and then subjected to alcohol extraction, filtration, and freeze-drying to obtain pentosan.

2. The method for extracting pentosans from wheat bran by combining irradiation and microbial fermentation according to claim 1, characterized in that: The method for activating Saccharomyces boulardii in step S3 is as follows: thawing the frozen Saccharomyces boulardii, inoculating it into a sterilized YPD solid culture medium, streaking and culturing it at 30° C., picking colonies with an inoculation loop and inoculating them into a sterilized YPD liquid culture medium, placing the culture medium in a shaker, and culturing it at 30° C. and 120-180 rpm for 24 hours to obtain an activated Saccharomyces boulardii liquid.

3. The method for extracting pentosans from wheat bran by combining irradiation and microbial fermentation according to claim 1, characterized in that: The activation method of Bacillus subtilis in step S3 is as follows: thawing the frozen Bacillus subtilis and inoculating it into a sterilized LB solid culture medium, culturing it at 37° C. for 24 hours, picking colonies with an inoculation loop and inoculating them into a sterilized LB liquid culture medium, and culturing it at 37° C. and 120-180 rpm for 24 hours to obtain an activated Bacillus subtilis bacterial solution.

4. The method for extracting pentosans from wheat bran by combining irradiation and microbial fermentation according to claim 1, characterized in that: The freezing temperature of the repeated freeze-thaw centrifugation in step S4 is (-30)-(-18)°C, the freezing time is 1-3h, the thawing temperature is 25-40°C, the number of freeze-thaw times is 2-5 times, the centrifugal speed is 3000-4000r / min, and the centrifugal time is 10-20min.

5. The method for extracting pentosans from wheat bran by combining irradiation and microbial fermentation according to claim 1, characterized in that: The alcohol extraction method in step S4 is to add 95% ethanol in a volume ratio of 1: (2-4) to the supernatant after centrifugation and let it stand at 2-6°C for 2-4 hours.

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