A method for preparing a bio-modified wheat bran containing xylo-oligosaccharides

Abstract

The application discloses a preparation method of bio-modified wheat bran containing xylo-oligosaccharide, and comprises the following steps: fermenting wheat bran by using mixed strains and composite enzymes; wherein the mixed strains comprise lactic acid bacteria, Saccharomyces cerevisiae and Bacillus licheniformis; and the composite enzymes comprise cellulase and xylanase. The preparation method provided by the application effectively reduces the contents of crude fiber and neutral detergent fiber in the wheat bran, increases the contents of crude protein and xylo-oligosaccharide in the fermented wheat bran, which are beneficial to the growth and development of animals, and improves the nutritional value of the wheat bran, so that the proportion of the wheat bran in feed application can be increased, and the addition amount of corn and soybean meal can be reduced.

Description

Technical Field

[0001] This invention relates to the field of agricultural and sideline product processing technology. More specifically, it relates to a method for preparing biomodified wheat bran containing xylooligosaccharides. Background Technology

[0002] Wheat bran is a low-to-medium energy byproduct produced during flour processing. It can be used as a feed ingredient, but its nutritional composition varies depending on the wheat variety and processing method. Generally, wheat bran contains 14.3–15.7% crude protein, 19.8–22.6% starch, and 3.9–4.0% crude fat. It also contains abundant bioactive substances, including xylooligosaccharide (XOS), β-glucan, and ferulic acid (FA). However, the high fiber content of wheat bran results in a relatively low effective energy value, limiting its application in livestock and poultry feed.

[0003] Xylooligosaccharides (XOS) are a major component of hemicellulose in cellulose-containing substances. They are oligosaccharides composed of 2–9 xylose molecules linked by β-1,4 glycosidic bonds, with the main active components including xylobiose, xylotriose, and xylotetraose. In the lower digestive tract of livestock and poultry, they undergo microbial fermentation to produce short-chain fatty acids. By lowering the pH of the livestock and poultry intestines, XOS promotes the growth of microorganisms related to intestinal health and inhibits the proliferation of harmful bacteria. Furthermore, XOS enhances innate immunity, improves antioxidant function, and improves intestinal morphology and structure in livestock and poultry. In livestock and poultry farming, their effects are manifested in improving intestinal health, thereby promoting the digestion and absorption of nutrients, and ultimately improving livestock and poultry production performance and feed utilization.

[0004] Microbial-enzyme co-fermentation technology is widely used in the feed industry. Its main purpose is to improve product quality through the synergistic effect of microorganisms and enzymes. However, there are few reports on using microbial-enzyme co-fermentation technology to increase the content of xylooligosaccharides in wheat bran. Summary of the Invention

[0005] The main objective of this invention is to provide a method for preparing biomodified wheat bran containing xylooligosaccharides.

[0006] To achieve the above objectives, the present invention provides the following technical solution:

[0007] This invention provides a method for preparing biomodified wheat bran containing xylooligosaccharides, including the step of fermenting wheat bran using mixed strains and compound enzymes;

[0008] The mixed bacterial strains include lactic acid bacteria, brewer's yeast and Bacillus licheniformis;

[0009] The complex enzyme includes cellulase and xylanase.

[0010] Preferably, the step of fermenting wheat bran using mixed microorganisms and compound enzymes refers to simultaneously fermenting wheat bran with mixed microorganisms and compound enzymes.

[0011] Preferably, the lactic acid bacteria is *Lactobacillus plantarum* with the preservation number CGMCC No. 27454.

[0012] The single-strain inoculation range for each of the lactic acid bacteria, Saccharomyces cerevisiae, or Bacillus licheniformis is independently 1×10⁻⁶. 6 CFU / g-1×10 8 CFU / g.

[0013] Preferably, the inoculation amounts of the lactic acid bacteria, brewer's yeast, and Bacillus licheniformis are 1×10⁻⁶. 6 CFU / g, 1×10 8 CFU / g, 1×10 8 CFU / g.

[0014] Preferably, the unit enzyme activity of the complex enzyme is 100-400 U / g, and more preferably 300 U / g.

[0015] Preferably, the ratio of cellulase to xylanase enzyme activity (U / g) is 1-7:3-9; more preferably 3-7:3-7, and even more preferably 7:3.

[0016] For example, the cellulase has an enzyme activity of at least 210 U / g; the xylanase has an enzyme activity of at least 90 U / g.

[0017] Preferably, the fermentation conditions are: a fermentation temperature of 28℃-34℃ and a fermentation time of 1-3 days.

[0018] Preferably, the fermentation process further includes a step of preparing wheat bran into a fermentation material, wherein the moisture content of the fermentation material is 50-55%.

[0019] Preferably, the biomodified wheat bran containing xylooligosaccharides has a crude protein content of 24.30% and a xylooligosaccharide content of 5.16 mg / g. The crude protein content and xylooligosaccharide content are the average values ​​obtained from three pilot-scale experiments conducted according to this invention.

[0020] The beneficial effects of this invention are as follows:

[0021] The preparation method provided by this invention effectively reduces the content of crude fiber and neutral detergent fiber in wheat bran, increases the content of xylooligosaccharides and crude protein in fermented wheat bran that are beneficial to animal growth and development, improves the nutritional value of wheat bran, increases the proportion of wheat bran in feed application, and is expected to reduce the amount of corn and soybean meal added.

[0022] The preparation method provided by this invention yields a bacterial enzyme-modified wheat bran containing xylooligosaccharides, which is a unique, low-cost, safer, and easily digestible feed resource that can replace part of soybean meal or corn. Compared with wheat bran raw materials, the dry basis crude protein content and xylooligosaccharide content are significantly increased, while the crude fiber content and neutral detergent fiber content are significantly reduced. Attached Figure Description

[0023] The specific embodiments of the present invention will be described in further detail below with reference to the accompanying drawings.

[0024] Figure 1 The figure shows the results of the lactic acid bacteria acid production experiment in the screening of fiber-degrading strains in Example 1.

[0025] Figure 2 The figure shows the results of the Bacillus licheniformis fiber degradation experiment in the screening of fiber-degrading strains in Example 1; where a shows the hydrolysis zone of Bacillus licheniformis on CMC-Na fiber medium, and b shows the hydrolysis zone of Bacillus licheniformis on wheat bran medium.

[0026] Figure 3 The figure shows the results of the lactic acid bacteria fiber degradation experiment in the screening of fiber-degrading strains in Example 1; where a shows the hydrolysis zone of LP17-1 on wheat bran medium, and b shows the hydrolysis zone of LP17-1 on CMC-Na fiber medium. Detailed Implementation

[0027] This invention discloses a method for preparing biomodified wheat bran containing xylooligosaccharides. Those skilled in the art can refer to this document and appropriately modify the process parameters to achieve the desired result. It should be particularly noted that all similar substitutions and modifications are obvious to those skilled in the art and are considered to be included in this invention. The method of this invention has been described through preferred embodiments, and those skilled in the art can clearly make modifications or appropriate alterations to the methods described herein without departing from the content, spirit, and scope of this invention to implement and apply the technology of this invention.

[0028] To further understand the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0029] Unless otherwise specified, all reagents involved in the embodiments of this invention are commercially available products and can be purchased through commercial channels.

[0030] The following are some of the sources of raw materials:

[0031] Both Bacillus licheniformis and Bacillus subtilis products were purchased from Beijing Xin Dayang Technology Development Co., Ltd.

[0032] The brewing yeast product was purchased from Angel Yeast Co., Ltd.

[0033] Cellulase, xylanase, and β-glucanase were all purchased from Xiasheng (Beijing) Biotechnology Development Co., Ltd.

[0034] RS047 and LP17-1 were isolated and deposited by our laboratory. The depository is the China General Microbiological Culture Collection Center (CGMCC), located at No. 3, Courtyard 1, Beichen West Road, Chaoyang District, Beijing, Institute of Microbiology, Chinese Academy of Sciences. RS047 is classified as *Enterococcus faecium*, with accession number CGMCC No. 19787, and deposited on May 8, 2020. LP17-1 is classified as *Lactobacillus plantarum*, with accession number CGMCC No. 27454, and deposited on May 24, 2023.

[0035] Example 1

[0036] Screening of fermentation strains

[0037] Raw materials: two types of Bacillus (Bacillus licheniformis and Bacillus subtilis), Saccharomyces cerevisiae, and preserved RS047 and LP17-1.

[0038] 1. Method

[0039] 1.1 Screening of fiber-degrading strains

[0040] Two frozen Bacillus strains, RS047 and LP17-1, and Saccharomyces cerevisiae were thawed and activated and cultured in suitable medium at 37°C (28°C for Saccharomyces cerevisiae). After activation, the strains were inoculated onto sodium carboxymethyl cellulose medium using a 200ml pipette tip and cultured at 37°C (28°C for Saccharomyces cerevisiae) for 48 hours. The inoculated plates were then stained with Congo red for 10 minutes. After staining, the Congo red stain was discarded, and sodium chloride solution was added for destaining. After destaining for 10 minutes, the plates were washed with ultrapure water, and the size of the cellulose hydrolysis zone was observed. The two strains with the largest cellulose hydrolysis zones (LP17-1 and Bacillus licheniformis) were selected for the following experiments.

[0041] 1.2 Inoculation Experiment with Wheat Bran Solid Culture Medium

[0042] LP17-1, Bacillus licheniformis, and Saccharomyces cerevisiae were inoculated onto wheat bran solid medium and conventional medium for each strain, respectively, and cultured at 37℃ (28℃ for Saccharomyces cerevisiae) for 48 h to investigate the growth of each strain on wheat bran medium and its degradation of wheat bran fiber.

[0043] Some results can be found in Figure 1-3 As shown, the experimental results indicate that *Lactobacillus plantarum* LP17-1 and *Bacillus licheniformis* both grew well on wheat bran medium. Congo red staining of the *Lactobacillus plantarum* LP17-1 and *Bacillus licheniformis* grown on wheat bran medium revealed obvious hydrolysis zones, indicating that the wheat bran fiber underwent degradation.

[0044] Example 2

[0045] The effects of solid-state fermentation and enzymatic hydrolysis on the nutritional value of wheat bran

[0046] 1. Fermentation raw materials: wheat bran, 3 kinds of bacteria (lactic acid bacteria LP17-1, Bacillus licheniformis, Saccharomyces cerevisiae), 3 kinds of enzymes (cellulase, xylanase, β-glucanase), and water.

[0047] 2. Method

[0048] Solid-state fermentation: Weigh 1000g of wheat bran, prepare the fermentation material with a material-to-water ratio of 1:1.5, and mix it with different microbial strains (single-strain, double-strain, and triple-strain solid-state fermentation according to the selected strains) for 3 days at a temperature of 37℃. The total inoculum size is 3×10⁻⁶. 7 Solid-state fermentation was carried out with CFU / g (the proportion of each single strain in the mixed fermentation group was the same). The fermentation samples were dried at 55℃, crushed and sieved, and the crude fiber, neutral detergent fiber and crude protein of the fermented wheat bran were detected.

[0049] Solid-state enzymatic hydrolysis: 1000g of wheat bran was weighed, with a material-to-water ratio of 1:1.5, and the hydrolysis time was 1 day at 37℃. Solid-state enzymatic hydrolysis was performed using single-enzyme, double-enzyme, and triple-enzyme methods. Solid-state enzymatic hydrolysis was carried out with a total enzyme addition of 400U / g (the proportion of each single enzyme in the compound enzyme hydrolysis group was the same). The hydrolyzed samples were dried at 55℃, pulverized, sieved, and the crude fiber, neutral detergent fiber, and reducing sugar levels of the fermented wheat bran were measured.

[0050] 3. Testing

[0051] Crude fiber (CF) content detection: Number the filter bags with a special marker, weigh the filter bags, and then weigh 0.95–1.00 g of sample (if the sample fat content is >5%, degreasing is required) and place it into the filter bag, avoiding sticking to the bag opening. Seal the bag 4 mm from the opening using a sealing machine. Accurately weigh one filter bag as a blank filter bag. Next, place the filter bag containing the sample and the empty filter bag into the filter bag rack of the ANKOM A2000I fully automated fiber analyzer. Then, add the pre-prepared sulfuric acid solution (0.13 ± 0.005 mol / L) and potassium hydroxide solution (0.23 ± 0.005 mol / L) to the acid and alkali reagent tanks of the fiber analyzer, respectively. Run the washing program according to the operating rules of the ANKOM A2000I fully automated fiber analyzer. After the fiber washing process is completed, remove the filter bag, gently press to squeeze out the liquid components, and then place the filter bag in an oven at (103±2)℃ for 4 hours to dry. Remove the dried filter bag from the oven, cool it, and weigh it. Then, place the filter bag in a pre-dried and weighed crucible and ashing it at (600±15)℃ for 2 hours. After ashing, cool it in a desiccator and weigh it. Calculate the dried weight of the washed sample, and then subtract the residue after ashing to obtain the weight loss of organic matter. Calculate the CF content using the following formula.

[0052]

[0053] In the formula, W1 is the weight of the filter bag (g).

[0054] W2 — Sample weight (g);

[0055] W3 — Mass of organic matter loss (g);

[0056] C1—Ash content factor of blank filter bag (ash loss mass of blank filter bag / mass of blank filter bag).

[0057] Neutral detergent fiber content testing: Performed in accordance with the requirements of GB / T 20806-2006 for the determination of neutral detergent fiber (NDF) in feed.

[0058] Crude protein content detection: Performed in accordance with the requirements of GB / T 6432-2018 for the determination of crude protein in feed;

[0059] Reducing sugar content detection: (1) Preparation of glucose standard curve: Take 100mg of glucose standard dried to constant weight and dilute to 100mL to obtain 1mg / ml glucose stock solution. Take 9 stoppered graduated test tubes and number them. Add 0, 0.2, 0.4, 0.6, 0.8, 1.0, 1.2, 1.4 and 1.6mL of glucose stock solution respectively. Make up to 2mL with distilled water to obtain glucose standard solution. Add 1.5mL of DNS reagent to each tube to prepare glucose reaction solution of different concentrations. Seal the prepared glucose reaction solution and boil it in a boiling water bath for 5min. Then take it out and cool it in a cold water bath. Then dilute to 25mL. Use tube No. 0 as control and measure the absorbance value at 540nm. Plot the glucose concentration as Y-axis and the absorbance value as X-axis to fit the standard curve. (2) Sample determination: Accurately weigh 3.00g of sample, transfer it to a 50ml centrifuge tube, add 27mL of boiled distilled water, shake for 30min to leach reducing sugars, and then centrifuge at 4000rpm for 5min. The supernatant at this point is a 10-fold dilution, which can be diluted to an appropriate factor as needed during the experiment. Take 4 stoppered test tubes and label them 0, 1, 2, and 3. Using the same method as preparing the standard curve, add 1mL of the test solution and 1mL of distilled water, and 1.5mL of DNS to test tubes 1-3 respectively, and add 2mL of distilled water and 1.5mL of DNS to the control tube 0. Seal the tubes and boil them in a water bath for 5min, cool them in a cold water bath, and make up to 25mL. Measure the absorbance at 540nm. Calculate the reducing sugar content in the sample based on the fitted curve. During the experiment, pay attention to ensuring that the dilution factor of the sample is within the range of good linearity of the standard curve, using OD... 540 The optimal range is 0.1 to 0.4.

[0060] Determination of xylooligosaccharide content: (1) Preparation of xylose standard curve: Take 100 mg of xylose standard dried to constant weight and dilute to 100 mL to obtain a 1 mg / mL xylose stock solution. Take 0, 10, 20, 30, 40, 50, 60, 100, 150, 200, 250, and 300 μL respectively into test tubes and add distilled water to 1 mL to obtain xylose standard solution. Take 1 mL of standard solution, add 5 mL of color reagent (2% phloroglucinol ethanol solution and equal volume of sulfuric acid), incubate at 100℃ for 10 min, cool to room temperature, accurately transfer 200 μL into a 96-well plate, and measure the absorbance value at a wavelength of 550 nm. Fit the standard curve with xylose concentration as the Y axis and absorbance value as the X axis. (2) Determination of sample: Accurately weigh 0.5-1 g of sample, add 50 mL of deionized water and mix well. After centrifugation at 2000 rpm, obtain the sample supernatant. Take 1 mL of sample supernatant, add 5 mL of colorimetric reagent (a mixture of 2% phloroglucinol ethanol solution and an equal volume of sulfuric acid), incubate at 100℃ for 10 min, and cool to room temperature. This is the sample solution before hydrolysis. Take 5 mL of sample supernatant, add 5 mL of 8% sulfuric acid solution, mix well, seal, and hydrolyze at 121℃ for 1 h. Take 1 mL of hydrolysate, add 5 mL of colorimetric reagent (a mixture of 2% phloroglucinol ethanol solution and an equal volume of sulfuric acid), incubate at 100℃ for 10 min, and cool to room temperature. This is the sample solution after hydrolysis. Accurately transfer 200 μL of each of the pre- and post-hydrolysis sample solutions into a 96-well plate and measure the OD value at a wavelength of 550 nm. Calculate the xylose content (C) in the sample based on the fitted curve.

[0061] C = (C2 - C1) × 0.88

[0062] In the formula: C—xylooligosaccharide content, 1 mg / mL;

[0063] C1—Xylose content of the sample before hydrolysis, 1 mg / mL;

[0064] C2—Xylose content of the sample after hydrolysis, 1 mg / mL;

[0065] 0.88 — the coefficient for xylose to xylooligosaccharide conversion.

[0066] 4. Results

[0067] (1) Solid-state fermentation results: The three strains were combined in single, dual, and triple forms for solid-state fermentation. The CF and NDF contents of each fermentation group are shown in Table 1 below. The experimental results showed that the triple fermentation combination was significantly better than the single and dual fermentation combinations. Among them, except for the single (Saccharomyces cerevisiae), dual (LP17-1 + Saccharomyces cerevisiae) and triple fermentation combinations, the other fermentation combinations showed varying degrees of mold growth. The CF and NDF contents of the triple fermentation combination were significantly lower than those of the single and dual fermentation groups (P<0.05). The optimal fermentation strains were determined to be Lactobacillus LP17-1, Bacillus licheniformis, and Saccharomyces cerevisiae.

[0068] Table 1. CF and NDF content (dry matter basis) of wheat bran fermented with single, double, and triple strains.

[0069]

[0070] Note: Data with the same letter under the same column indicate no significant difference; data with different lowercase letters under the same column indicate significant differences (P<0.05); # indicates mold growth in the fermentation group.

[0071] (2) Solid-state enzymatic hydrolysis results: Cellulase, xylanase, and β-glucanase were combined in single-enzyme, double-enzyme, and triple-enzyme forms for solid-state enzymatic hydrolysis. The CF and reducing sugar contents of each hydrolysis group are shown in Table 2 below. The experimental results show that the cellulase + xylanase combination is significantly better than the single-enzyme, triple-enzyme, and other double-enzyme combinations. The CF content of the cellulase + xylanase combination is significantly lower than that of the xylanase, β-glucanase, and xylanase + β-glucanase hydrolysis groups (P<0.05), but not significantly different from the cellulase, cellulase + β-glucanase, and 3-enzyme complex hydrolysis groups (P>0.05). The reducing sugar content is significantly higher than that of the xylanase hydrolysis group (P<0.05), but not significantly different from other hydrolysis groups (P>0.05), although it is at a relatively high level. Considering production costs and process, the optimal enzymatic hydrolysis combination is determined to be cellulase + xylanase.

[0072] Table 2. Combination Fibre (CF) and Reducing Sugar Content (Dry Matter Basis) of Wheat Bran by Single Enzyme, Double Enzyme, and Triple Enzyme Hydrolysis

[0073]

[0074] Note: Data with the same letter in the same column indicate no significant difference; data with different lowercase letters in the same column indicate significant differences (P<0.05).

[0075] Example 3: Effects of different microbial ratios on fermented wheat bran indicators

[0076] The method of Example 2 was followed, except that: an orthogonal experiment for fermenting wheat bran was designed as shown in Tables 3 and 4, solid-state fermentation was carried out with different microbial strain ratios, and then the crude fiber, neutral detergent fiber and crude protein were measured. The results are shown in Table 5.

[0077] Table 3 Orthogonal experimental design for fermented wheat bran

[0078] level Lactobacillus Saccharomyces cerevisiae Bacillus licheniformis 1 <![CDATA[1×10 6 CFU / g]]> <![CDATA[1×10 6 CFU / g]]> <![CDATA[1×10 6 CFU / g]]> 2 <![CDATA[1×10 7 CFU / g]]> <![CDATA[1×10 7 CFU / g]]> <![CDATA[1×10 7 CFU / g]]> 3 <![CDATA[1×10 8 CFU / g]]> <![CDATA[1×10 8 CFU / g]]> <![CDATA[1×10 8 CFU / g]]>

[0079] Table 4 Orthogonal Experiment Combinations

[0080] serial number Different level combinations Lactobacillus Saccharomyces cerevisiae Bacillus licheniformis 1 <![CDATA[L1S1B1]]> 1 1 1 2 <![CDATA[L1S2B3]]> 1 2 3 3 <![CDATA[L1S3B2]]> 1 3 2 4 <![CDATA[L2S1B3]]> 2 1 3 5 <![CDATA[L2S2B2]]> 2 2 2 6 <![CDATA[L2S3B1]]> 2 3 1 7 <![CDATA[L3S1B2]]> 3 1 2 8 <![CDATA[L3S2B1]]> 3 2 1 9 <![CDATA[L3S3B3]]> 3 3 3

[0081] Table 5. Results of Fermented Wheat Bran Index Testing

[0082]

[0083]

[0084] Table 5 shows that different microbial inoculum amounts have different effects on the indicators. Based on the intersubjectivity effect test, the optimal combination of compound strains L1S3B3 is obtained, that is, the inoculum amounts of lactic acid bacteria, saccharomyces cerevisiae, and Bacillus licheniformis in the compound strain are 1×10⁻⁶. 6 CFU / g, 1×10 8 CFU / g, 1×10 8 CFU / g, fermented wheat bran yields the best results.

[0085] Example 4: Effects of different enzyme dosages and ratios on fermented wheat bran indicators

[0086] Following the method in Example 2, a solid-state enzymatic hydrolysis experiment was designed to determine the total amount of enzyme added for hydrolyzing wheat bran (with the same proportion of each single enzyme) and the enzyme activity ratio of each single enzyme. Then, the indicators of crude fiber, neutral detergent fiber and reducing sugar were determined. The results are shown in Tables 6 and 7.

[0087] Table 6. Results of Enzymatic Hydrolysis Indicators of Wheat Bran with Different Total Enzyme Addition Amounts

[0088] Enzymatic digestion group reducing sugar mg / g Dry basis crude fiber % Dry-based neutral detergent fiber % 100U / g <![CDATA[241.54±17.20 b ]]> <![CDATA[12.66±0.34 b ]]> <![CDATA[41.17±1.14 b ]]> 200U / g <![CDATA[261.91±23.03 ab ]]> <![CDATA[12.03±0.20 c ]]> <![CDATA[41.57±0.09 b ]]> 300U / g <![CDATA[284.71±14.54 a ]]> <![CDATA[11.16±0.14 d ]]> <![CDATA[41.50±1.17 b ]]> 400U / g <![CDATA[259.71±22.84 ab ]]> <![CDATA[11.23±0.21 d ]]> <![CDATA[41.27±0.13 b ]]> wheat bran raw materials <![CDATA[62.10±3.71 c ]]> <![CDATA[15.10±0.10 a ]]> <![CDATA[55.35±0.34 a ]]>

[0089] Table 7. Detection results of enzyme activity ratios for wheat bran hydrolysis at a total enzyme addition of 300 U / g.

[0090] Enzymatic hydrolysis group (cellulase: xylanase) reducing sugar mg / g Dry basis crude fiber % Dry-based neutral detergent fiber % 0:1 <![CDATA[173.57±15.84 d ]]> <![CDATA[13.16±0.16 b ]]> <![CDATA[43.53±0.23 b ]]> 1:9 <![CDATA[265.08±11.39 b ]]> <![CDATA[12.77±0.32 b ]]> <![CDATA[41.10±0.17 de ]]> 3:7 <![CDATA[292.21±10.2 a ]]> <![CDATA[12.15±0.24 c ]]> <![CDATA[42.08±0.11 cd ]]> 5:5 <![CDATA[284.94±8.87 a ]]> <![CDATA[11.66±0.14 d ]]> <![CDATA[42.17±0.30 c ]]> 7:3 <![CDATA[281.57±8.01 a ]]> <![CDATA[11.12±0.33 e ]]> <![CDATA[41.60±0.54 cde ]]> 9:1 <![CDATA[241.20±8.34 c ]]> <![CDATA[10.86±0.36 e ]]> <![CDATA[40.80±0.70 e ]]> 1:0 <![CDATA[257.89±12.93 b ]]> <![CDATA[10.75±0.33 e ]]> <![CDATA[41.70±1.23 cde ]]> wheat bran raw materials <![CDATA[62.10±3.71 f ]]> <![CDATA[15.10±0.10 a ]]> <![CDATA[55.35±0.34 a ]]>

[0091] As shown in Tables 6-7, the results of the single-enzyme ratio experiment of the compound enzyme indicate that when the ratio of cellulase to xylanase in the compound enzyme is 7:3, the crude fiber content of the enzymatically hydrolyzed wheat bran reaches the lowest level, while the reducing sugar content reaches the highest level, with crude fiber and reducing sugar contents of 11.12% and 271.57 mg / g, respectively. Therefore, the optimal single-enzyme ratio of the compound enzyme is determined to be 7:3 for cellulase to xylanase.

[0092] Example 5: Effects of different fermentation conditions on fermented wheat bran indicators

[0093] Following the method of Example 2, a response surface methodology experiment for the co-fermentation of wheat bran by bacteria and enzymes was designed as shown in Tables 8 and 9. Fermentation time, water-to-material ratio, and fermentation temperature were used as response surface methodology factors. Then, the crude fiber, neutral detergent fiber, reducing sugar, and crude protein were measured. The results are shown in Table 10.

[0094] Table 8 Response surface methodology for synergistic fermentation of wheat bran by microorganisms and enzymes.

[0095]

[0096] Table 9 Response Surface Experiment Combinations

[0097] Test No. Fermentation time / h Water to material ratio Fermentation temperature / ℃ Test No. Fermentation time / h Water to material ratio Fermentation temperature / ℃ 1 24 0.9 31 10 48 1.5 28 2 72 0.9 31 11 48 0.9 34 3 24 1.5 31 12 48 1.5 34 4 72 1.5 31 13 48 1.2 31 5 24 1.2 28 14 48 1.2 31 6 72 1.2 28 15 48 1.2 31 7 24 1.2 34 16 48 1.2 31 8 72 1.2 34 17 48 1.2 31 9 48 0.9 28

[0098] Table 10 Results of response surface methodology analysis for synergistic fermentation of wheat bran by microorganisms and enzymes

[0099]

[0100]

[0101] Conclusion: The optimal fermentation conditions include: co-fermentation of wheat bran with Lactobacillus plantarum LP17-1, Saccharomyces cerevisiae, and Bacillus licheniformis, with single inoculum amounts of 1×10⁻⁶. 6 1×10 8 1×10 8 CFU / g. Total addition of cellulase and xylanase was 300 U / g, with a cellulase:xylanase ratio of 7:3; fermentation time was 72 h, fermentation material-to-water ratio was 1:1.1, and fermentation temperature was 34 ℃.

[0102] Example 6: Small-scale scale-up test

[0103] A 15kg wheat bran fermentation system was set up (wheat bran fermentation system: wheat bran was prepared into fermentation material, and mixed bacteria and compound enzymes were added under the optimal conditions obtained according to Examples 2-5. The fermentation time was 72h, the water ratio of fermentation material was 1:1.1, and the fermentation temperature was 34℃). Small-scale scale-up experiments were conducted, and the contents of CF, NDF, etc. in each fermentation group were measured as shown in Table 11 below.

[0104] Table 11 Results of CP, CF and other content determination in three batches of fermented wheat bran in pilot-scale testing (dry matter basis, %)

[0105]

[0106] Conclusion: The scale-up fermentation results of three batches showed that the crude protein content of fermented wheat bran was 24.30±0.58%, an increase of 33.66% compared to regular wheat bran; the crude fiber content was 10.47±0.39%, a decrease of 32.01% compared to regular wheat bran; the neutral detergent fiber content was 35.79±0.64%; and the reducing sugar content was 241.47±12.2 mg / g. The xylooligosaccharide content of fermented wheat bran increased significantly after fermentation (P<0.05), reaching 5.16±0.13 mg / g, an increase of 158.3% compared to before fermentation, and an increase of 209.4% compared to regular wheat bran. The fermented wheat bran exhibited good repeatability and high fermentation process stability. It can be identified as a suitable process for subsequent fermented wheat bran production.

[0107] Obviously, the above embodiments of the present invention are merely examples for clearly illustrating the present invention, and are not intended to limit the implementation of the present invention. For those skilled in the art, other variations or modifications can be made based on the above description. It is impossible to exhaustively list all the implementation methods here. All obvious variations or modifications derived from the technical solutions of the present invention are still within the protection scope of the present invention.

Claims

1. A method for preparing biomodified wheat bran containing xylooligosaccharides, characterized in that, This includes the step of fermenting wheat bran using mixed strains and compound enzymes; The mixed bacterial strain consists of lactic acid bacteria, brewer's yeast, and Bacillus licheniformis; the lactic acid bacteria is Lactobacillus plantarum with preservation number CGMCC No. 27454. The inoculation amounts of the lactic acid bacteria, Saccharomyces cerevisiae, and Bacillus licheniformis were 1×10⁻⁶. 6 CFU / g, 1×10 8 CFU / g, 1×10 8 CFU / g; The complex enzyme is composed of cellulase and xylanase; the enzyme activity ratio of the cellulase and xylanase is 7:3; the unit enzyme activity of the complex enzyme is 300 U / g; Before fermentation, the process also includes preparing the wheat bran into a fermentation mixture, with a water-to-fermentation ratio of 1:1.

1. The fermentation temperature was 34℃, and the fermentation time was 3 days.

2. The preparation method according to claim 1, characterized in that, The biomodified wheat bran has a crude protein content of 24.30% and a xylooligosaccharide content of 5.16 mg / g.

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