An oat bran composition for modulating gut flora and a method of preparing the same

Abstract

This invention discloses an oat bran composition for regulating intestinal flora and its preparation method, relating to the field of food processing technology. The oat bran composition comprises oat bran, oat β-glucan concentrate, tremella powder, inulin, resistant dextrin, fructooligosaccharides, soybean flour, coconut milk powder, jujube powder, and goji berry powder. This invention also provides a method for preparing the composition, wherein the oat β-glucan concentrate is obtained by pretreatment with ferulic acid esterase, synergistic extraction, ultrafiltration, alcohol precipitation, and drying. Compared with existing technologies, the oat bran composition prepared by this invention has advantages such as good hot water resolubility, resistance to clumping after reconstitution, high suspension stability, smooth taste, and benefits in lowering cholesterol, regulating blood lipids, and increasing the production of short-chain fatty acids during in vitro intestinal fermentation.

Description

Technical Field

[0001] This invention relates to the field of food processing technology, and in particular to an oat bran composition for regulating intestinal flora and its preparation method. Background Technology

[0002] Oat bran is one of the main byproducts of oat processing, containing dietary fiber, protein, oat β-glucan, and phenolic acids, and has high resource utilization value. Targeted extraction and functionalization of β-glucan from oat bran can increase the added value of oat processing byproducts and provide a raw material basis for instant cereal and dietary fiber foods. Oat β-glucan is a linear non-starch polysaccharide formed by β-D-glucan units linked by β-(1→3) and β-(1→4) glycosidic bonds. Its molecular weight and molecular chain conformation affect solubility, solution viscosity, water-holding capacity, and fermentation accessibility. Medium- and high molecular weight β-glucans typically have higher solution viscosity and water-holding capacity, and can influence bile acid migration and cholesterol absorption by altering the rheological state of digestive tract contents; medium- and low molecular weight β-glucans have better diffusivity and fermentation accessibility, are more easily utilized by intestinal flora, and promote the production of short-chain fatty acids. Therefore, molecular weight classification of oat β-glucan and its appropriate blending ratio can help balance the product's mixing viscosity, suspension stability, and intestinal fermentation utilization, providing a technical basis for the subsequent preparation of β-glucan components with different molecular weights.

[0003] CN104783040A discloses a food composition derived from oat bran and a method for manufacturing the same, providing a food composition derived from oat bran, particularly from naked oats, and a method for manufacturing the same. The composition, obtained through a process including at least a pulverization step of crushing oat bran to physically disrupt its cell walls, thereby releasing β-glucan into the pulverized material, and a step of acting on the pulverized material with at least one enzyme selected from phytase, cellulase, lysozyme, and xylanase, is not only rich in β-glucan but also in dietary fiber, protein, lipids, minerals, and other beneficial nutrients. CN107467639A discloses a method for co-producing oat β-glucan nutritional powder and dietary fiber micro-powder, which improves the utilization rate of β-glucan, dietary fiber, and protein components in oat bran by inactivating enzymes, extracting, and comprehensively utilizing byproducts from oat bran. While the solutions reported in the aforementioned patent literature can improve the release rate, extraction purity, or comprehensive utilization rate of β-glucan to some extent, none of them simultaneously solve the problems of insufficient release of oat β-glucan, poor hot water resolubility of the powder, easy clumping and stratification of the composition after reconstitution, and unstable in vitro intestinal fermentation utilization. In practical use, these solutions easily lead to problems such as obvious powder clumping in instant products, insufficient suspension stability, uneven taste, and insufficient utilization of functional dietary fiber. Therefore, there is a need to provide an oat bran composition and its preparation method that can improve the release rate of oat β-glucan, improve reconstitution stability, and promote intestinal flora fermentation utilization. Summary of the Invention

[0004] In view of the shortcomings of the prior art, the technical problem to be solved by the present invention is to provide an oat bran composition for regulating intestinal flora and its preparation method. By improving the preparation process of oat β-glucan concentrate powder, the resulting composition has good hot water reconstitution properties, suspension stability and in vitro intestinal fermentation effect.

[0005] To achieve the above objectives, the present invention provides an oat bran composition for regulating intestinal flora, comprising the following components by weight: 45-70 parts oat bran, 3-10 parts oat β-glucan concentrate powder, 3-12 parts tremella powder, 2-10 parts inulin, 2-8 parts resistant dextrin, 1-5 parts fructooligosaccharide, 2-10 parts soybean powder, 2-8 parts coconut milk powder, 0.5-5 parts jujube powder, and 0.5-3 parts goji berry powder.

[0006] Preferably, the oat bran composition for regulating intestinal flora comprises, by weight, the following components: 52-64 parts oat bran, 4-8 parts oat β-glucan concentrate powder, 5-10 parts tremella powder, 4-8 parts inulin, 3-7 parts resistant dextrin, 2-4 parts fructooligosaccharides, 4-8 parts soybean flour, 3-6 parts coconut milk powder, 1-3 parts jujube powder, and 0.5-2 parts goji berry powder.

[0007] Furthermore, the oat β-glucan concentrate powder is prepared according to the following method:

[0008] (1) Pretreatment of oat bran powder: Take food-grade oat bran, remove impurities and crush it, pass it through a 40-80 mesh sieve to obtain oat bran powder; spray water into the oat bran powder to adjust the moisture content of the oat bran powder to 10-18%, let it stand for equilibration for 10-40 minutes; then steam treat it at 90-105℃ for 3-12 minutes, after steam treatment, dry it with hot air at 45-60℃ to a moisture content of 6-9% to obtain pretreated oat bran powder;

[0009] (2) Add the pretreated oat bran powder to a citrate-sodium citrate buffer solution with a pH of 5-6.2. The weight-to-volume ratio of the pretreated oat bran powder to the buffer solution is 1 kg: (6-10) L. Pre-swell at 45-50℃ and 60-120 r / min for 10-20 min. Then adjust the temperature to 45-55℃ and add ferulic acid esterase. The amount of ferulic acid esterase added is 0.01-0.06% of the weight of the pretreated oat bran powder. Treat at 45-55℃ for 20-90 min with a stirring speed of 80-180 r / min. After the reaction is completed, raise the temperature of the system to 80-90℃ and keep it at that temperature for 5-10 min to obtain the enzymatically hydrolyzed pretreated slurry.

[0010] (3) Add eutectic solvent extract to the enzymatic pretreatment slurry, and control the weight-volume ratio of pretreated oat bran powder to eutectic solvent extract to be 1 kg: (8-15) L. Extract at 45-60℃ for 40-120 min with a stirring speed of 100-220 r / min. After extraction, centrifuge and collect the supernatant. Add 3-8 times the weight of water to the precipitate and stir and extract at 40-50℃ for 10-40 min. After centrifugation, combine the supernatants to obtain crude β-glucan extract.

[0011] The crude β-glucan extract was heated to 78-90℃, the pH was adjusted to 5.8-6.5, and thermostable α-amylase was added at a rate of 0.03-0.1% of the weight of the pretreated oat bran powder. The mixture was kept at this temperature for 15-40 min. Subsequently, the system was cooled to 50-65℃, the pH was adjusted to 4.8-5.5, pullulanase was added at a rate of 0.01-0.05% of the weight of the pretreated oat bran powder, and the mixture was kept at this temperature for another 15-50 min. After treatment, samples were taken to determine the total starch content. When the total starch content was not higher than 0.5% on a dry basis, the temperature was raised to 90℃. Inactivate the enzyme at 100℃ for 3-10 min to obtain a destarched solution; cool the destarched solution to 45-55℃, adjust the pH to 6-7, add neutral protease at 0.02-0.08% of the weight of the pretreated oat bran flour, and treat for 25-70 min; after treatment, raise the temperature to 85-95℃ and inactivate the enzyme for 3-10 min, then adjust the pH to 4.2-4.8, and let stand for 15-60 min to allow proteins and colloidal impurities to aggregate and settle; after standing, centrifuge and collect the supernatant to obtain a deproteinized β-glucan solution.

[0012] (4) The deproteinized β-glucan solution is passed sequentially through an 80-120 mesh sieve and a 0.22-0.8 μm microfiltration membrane to obtain a clear β-glucan solution; the clear β-glucan solution is first fractionated using an ultrafiltration membrane with a molecular weight cutoff of 200-500 kDa to obtain retentate A and permeate B; retentate A is washed using the 200-500 kDa ultrafiltration membrane, and an equal volume of water is added every time it is concentrated to 1 / 2-1 / 4 of its original volume, and the washing and filtration are repeated 2-6 times to obtain the medium-to-high molecular weight β-glucan component, and then... The permeate produced by washing and filtration is combined with permeate B; the combined permeate is concentrated and washed using an ultrafiltration membrane with a molecular weight cutoff of 20-50 kDa. An equal volume of water is added each time the concentration reaches 1 / 2-1 / 4 of the original volume, and the washing and filtration is repeated 2-6 times. After washing and filtration, the concentration is continued until the solid content is 6-12%, yielding a low-to-medium molecular weight β-glucan component; the high-to-medium molecular weight β-glucan component and the low-to-medium molecular weight β-glucan component are mixed at a mass ratio of (6-8):(2-4) to obtain a compound β-glucan concentrate; Add ethanol to the concentrated β-glucan solution to achieve an ethanol volume fraction of 65-85%. Stirring should be maintained during the addition process at a speed of 60-150 r / min. After the addition is complete, allow the system to stand at 0-10℃ for 3-10 h. After standing, centrifuge to collect the precipitate, and wash it 1-3 times with a 65-85% ethanol aqueous solution to obtain wet β-glucan precipitate. Add the wet β-glucan precipitate to water to adjust the solid content to 8-15%, and then heat at 45-55℃. Stir at low speed for 30-60 min, then pre-homogenize at 10-15 MPa 1-2 times, and then fine homogenize at 20-35 MPa 1-2 times to obtain a β-glucan complex dispersion. Dispense the β-glucan complex dispersion into freeze-drying pans, control the material layer thickness to be 5-15 mm, and pre-freeze at -35℃ to -50℃ for 4-10 h. Then freeze-dry under a vacuum degree not exceeding 80 Pa for 18-36 h. After freeze-drying, pulverize and pass through a 60-100 mesh sieve to obtain oat β-glucan concentrate powder.

[0013] The eutectic solvent extract is composed of a hydrogen bond acceptor, a hydrogen bond donor, and water; the hydrogen bond acceptor is one or more of L-proline, betaine, L-carnitine, choline acetate, and glycine; the hydrogen bond donor is one or more of gluconic acid, L-malic acid, lactic acid, L-tartaric acid, succinic acid, and citric acid; and the molar ratio of the hydrogen bond acceptor, hydrogen bond donor, and water is 1:(0.8-3):(6-18).

[0014] Preferably, the eutectic solvent extract is composed of L-proline, gluconic acid and water, and the molar ratio of L-proline, gluconic acid and water is 1:(0.8-1.5):(8-14).

[0015] Further, the preparation method of the eutectic solvent extract is as follows: weigh hydrogen bond acceptor, hydrogen bond donor and water according to the ratio, first add hydrogen bond acceptor and hydrogen bond donor to the preparation tank, stir at 50-70℃ for 10-40 min; then add water, continue stirring at 50-70℃ for 20-60 min to obtain eutectic solvent mother liquor; dilute the eutectic solvent mother liquor with water so that the mass fraction of the eutectic solvent mother liquor in the eutectic solvent extract is 20-40%, to obtain the eutectic solvent extract.

[0016] The present invention also provides a method for preparing an oat bran composition for regulating intestinal flora.

[0017] A method for preparing an oat bran composition for regulating gut microbiota includes the following steps:

[0018] S1. Take oat bran, remove impurities and place it in a steam cooking device, treat it at 90-100℃ for 8-20 minutes; then dry it with hot air at 45-65℃ until the moisture content is no more than 6.5%, pulverize it and pass it through a 60-100 mesh sieve to obtain pretreated oat bran.

[0019] S2. Take dried white fungus, remove impurities, soak in water for 1-4 hours, drain, and steam at 95-105℃ for 20-60 minutes; pre-freeze the steamed white fungus at -25℃ to -45℃ for 4-10 hours, then freeze-dry at a vacuum degree not higher than 80Pa for 12-30 hours, pulverize and pass through a 60-100 mesh sieve to obtain white fungus powder.

[0020] S3. Add oat β-glucan concentrate, inulin, resistant dextrin and oligofructose to a mixer and mix at 10-30 r / min for 5-20 min to obtain a compound dietary fiber premix.

[0021] S4. Add the pretreated oat bran, tremella powder and compound dietary fiber premix to the mixing equipment and mix for 10-25 minutes; then add soybean powder, coconut milk powder, red date powder and goji berry powder and continue mixing for 5-20 minutes to obtain the initial mixture;

[0022] S5. Spray water into the initial mixture, the amount of water being 3-8% of the total weight of the initial mixture, the spraying pressure being 0.1-0.4 MPa, and stirring while spraying, so that the powder forms loose particles with a particle size of 0.2-1.5 mm; pre-freeze the loose particles at -25℃ to -45℃ for 4-10 h, and then freeze-dry them at a vacuum degree not exceeding 80 Pa for 12-30 h to obtain the oat bran composition;

[0023] S6. Packaging: The oat bran composition is packaged with nitrogen, and the oxygen content of the packaging is controlled below 3%.

[0024] First, ferulic acid esterase is used to directionally decrosslink the ferulic acid ester bonds in the cell wall of oat bran, reducing the embedding degree of β-glucan in the cell wall, hemicellulose, and protein complex structure. Then, the hydrogen bond network and mild solvation effect of the eutectic solvent promote cell wall swelling, allowing β-glucan to be released under relatively mild conditions. Subsequently, ultrafiltration is used to remove small molecules and low molecular weight impurities of the eutectic solvent, and molecular weight fractionation is used to control the molecular weight distribution of β-glucan, resulting in oat β-glucan concentrate powder with good resolubility, suspension stability, and in vitro fermentation accessibility. The medium and high molecular weight components act on cholesterol absorption and bile acid excretion through viscosity effects, while the medium and low molecular weight components participate in lipid metabolism regulation by improving the fermentation accessibility of the microbial community and promoting the production of acetic acid, propionic acid, and butyric acid. The synergistic effect of the two is beneficial to improve cholesterol and blood lipid indicators and regulate the intestinal flora, avoiding the problems of excessive viscosity of a single medium and high molecular weight component or insufficient viscosity contribution of a single medium and low molecular weight component. The homogenized β-glucan dispersion and the wet particles formed by microaggregation are pre-frozen and vacuum freeze-dried to reduce the impact of high-temperature drying on the β-glucan molecular chain and form a loose porous structure, which is beneficial for maintaining molecular weight distribution and improving powder resolubility. L-proline contains amino, carboxyl, and cyclic structures, and can provide amino acid-type hydrogen bond acceptors and zwitterionic interactions; gluconic acid contains carboxyl and multiple hydroxyl groups, and can provide polyhydroxy carboxylic acid-type hydrogen bond donors. In the presence of water, the two form a eutectic hydrogen bond network, giving the extraction system good wetting, swelling, and solubilizing capabilities. After pretreatment with ferulic acid esterase, some ferulic acid ester bonds in the oat bran cell wall are cleaved, weakening the β-glucan embedding structure. At this time, the eutectic solvent can further weaken the non-covalent bonds between β-glucan and proteins, hemicellulose, and residual cell wall structures, promoting β-glucan release.

[0025] The beneficial effects of this invention are:

[0026] 1. This invention employs a combination of ferulic acid esterase pretreatment and eutectic solvent synergistic extraction. First, it directionally weakens the cross-linking of ferulic acid esters in the cell wall of oat bran and their encapsulation effect on β-glucan. Then, it utilizes the hydrogen bond network formed by the eutectic solvent to promote cell wall swelling and β-glucan dissolution, thereby improving the release degree and extraction yield of β-glucan.

[0027] 2. This invention utilizes ultrafiltration membranes to fractionate β-glucan by molecular weight, and then blends medium- and high-molecular-weight β-glucan components with medium- and low-molecular-weight β-glucan components in a specific ratio. Medium- and high-molecular-weight β-glucans can form suitable viscosity and hydration networks, which is beneficial for delaying cholesterol absorption and promoting bile acid excretion; medium- and low-molecular-weight β-glucans have better accessibility to intestinal flora fermentation, which is beneficial for promoting the production of short-chain fatty acids such as acetic acid, propionic acid, and butyric acid, thus enabling β-glucans of different molecular weights to have a synergistic effect in lipid regulation and intestinal flora regulation.

[0028] 3. This invention combines oat β-glucan concentrate obtained by molecular weight fractionation with oat bran, tremella powder, inulin, resistant dextrin, fructooligosaccharides and other components, and forms a loose and porous granular structure by spray-drying and micro-agglomeration and freeze-drying. This improves the wetting, dispersion and resolubility of the powder, making the resulting oat bran composition less prone to clumping when mixed with hot water, with good suspension stability and a smooth taste. At the same time, it is beneficial to increase the amount of short-chain fatty acids generated in the in vitro intestinal fermentation system. Detailed Implementation

[0029] The endpoints and any values ​​of the ranges disclosed in this invention are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed in this invention.

[0030] The heat-resistant α-amylase, model FDY-3801, was purchased from Ningxia Xiasheng Industrial Group Co., Ltd.

[0031] Neutral protease, enzyme activity 50,000 U / g;

[0032] Ferulic acid esterase was purchased from Megazyme (Bray, Co. Wicklow, Ireland);

[0033] Amylase, also known as glucoamylase, is a food-grade enzyme with an enzyme activity of 100,000 U / g. The product is model FDG-2228 and was purchased from Ningxia Xiasheng Industrial Group Co., Ltd.

[0034] Pullulanase, food grade, enzyme activity 2000U / mL, model FDY-2224, purchased from Ningxia Xiasheng Industrial Group Co., Ltd.

[0035] Other raw materials not mentioned are all common raw materials. The above content is only for the purpose of illustrating the present invention and should not be construed as a strict limitation of the present invention. Those skilled in the art can directly purchase the same / similar raw materials from the market or prepare them themselves.

[0036] The technical solutions of the present invention will be clearly and completely described below with reference to specific embodiments. 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 skilled in the art without creative effort are within the scope of protection of the present invention.

[0037] Example 1

[0038] An oat bran composition for regulating intestinal flora, comprising the following components by weight: 58 parts oat bran, 6 parts oat β-glucan concentrate powder, 8 parts tremella powder, 6 parts inulin, 5 parts resistant dextrin, 3 parts fructooligosaccharide, 6 parts soybean powder, 5 parts coconut milk powder, 2 parts jujube powder, and 1 part goji berry powder.

[0039] The preparation method of the above-mentioned oat bran composition for regulating intestinal flora includes the following steps:

[0040] S1. Oat bran pretreatment: Take 58 portions of oat bran, remove impurities and place them in a steam cooking device. Treat them at 95℃ for 12 minutes to gelatinize the starch in the oat bran and reduce the raw bran taste. Then dry them with hot air at 55℃ until the moisture content is no more than 6%. After crushing, pass them through an 80-mesh sieve to obtain pretreated oat bran.

[0041] S2. Preparation of Tremella powder: Take dried Tremella, remove impurities and soak in water for 2 hours. After draining, steam at 100℃ for 35 minutes to soften the Tremella tissue and release some Tremella polysaccharides. Pre-freeze the steamed Tremella at -35℃ for 6 hours, then freeze-dry at a vacuum degree not higher than 50Pa for 18 hours. After pulverizing, pass through an 80-mesh sieve to obtain Tremella powder.

[0042] S3. Fiber premix: Add 6 parts of oat β-glucan concentrate, 6 parts of inulin, 5 parts of resistant dextrin and 3 parts of oligofructose to a mixer and mix at 20 r / min for 10 min to obtain a compound dietary fiber premix.

[0043] S4. Mixing the main ingredients: Add the pretreated oat bran obtained in step S1, the tremella powder obtained in step S2, and the compound dietary fiber premix obtained in step S3 into a three-dimensional mixer and mix for 15 minutes; then add 6 parts of soybean powder, 5 parts of coconut milk powder, 2 parts of red date powder, and 1 part of goji berry powder, and continue mixing for 12 minutes to obtain the initial mixture.

[0044] S5. Microagglomeration treatment: Water is sprayed into the initial mixture at a volume of 5.5% of the total weight of the initial mixture and a spraying pressure of 0.2 MPa. The mixture is stirred while spraying to form loose particles with a particle size of 0.3 mm to 1.2 mm. The loose particles are pre-frozen at -35°C for 6 hours and then freeze-dried under a vacuum of 50 Pa for 18 hours to obtain an oat bran composition.

[0045] S6. Packaging: The oat bran composition obtained in step S5 is packaged in nitrogen-filled bags of 35g each, with the oxygen content of the packaging controlled below 2%.

[0046] The oat β-glucan concentrate powder was prepared according to the following method:

[0047] (1) Take 100 kg of food-grade oat bran, remove coarse impurities by vibrating screen and remove metal foreign objects by magnetic separation, crush the oat bran after impurity removal and pass it through a 60-mesh sieve to obtain oat bran powder; spray water evenly into the oat bran powder to adjust the moisture content of the oat bran powder to 14%, and let it stand for 20 min to balance; then place the moisture-adjusted oat bran powder in a steam treatment device and steam treat it at 98℃ for 6 min; after the steam treatment, dry the oat bran powder with hot air at 50℃ until the moisture content is 7.5% to obtain pretreated oat bran powder;

[0048] (2) Take 100 kg of pretreated oat bran powder obtained in step (1), add 1000 L of water, stir evenly and adjust the pH to 6.2, extract at 60℃ for 90 min, stirring speed is 160 r / min; after extraction, centrifuge at 5000 r / min for 15 min and collect the supernatant; add 5 times the weight of water to the precipitate, stir and extract at 45℃ for 20 min, centrifuge and combine the two supernatants to obtain β-glucan crude extract;

[0049] (3) The crude β-glucan extract obtained in step (2) was heated to 82°C, the pH was adjusted to 6, and a thermoresistant α-amylase was added at a rate of 0.06% of the weight of the pretreated oat bran powder. The mixture was kept at this temperature for 25 min. Subsequently, the system was cooled to 58°C, the pH was adjusted to 5, and a saccharifying enzyme was added at a rate of 0.03% of the weight of the pretreated oat bran powder. The mixture was kept at this temperature for 35 min. After the treatment was completed, the system was heated to 95°C and kept at this temperature for 5 min to inactivate the enzyme, thus obtaining the destarch-treated solution. The above-mentioned destarched liquid was cooled to 50℃, the pH was adjusted to 6.5, and neutral protease was added at a rate of 0.05% of the weight of the pretreated oat bran powder. The treatment lasted for 45 min. After the treatment, the system was heated to 90℃ and kept at that temperature for 5 min to inactivate the enzyme. Then the pH was adjusted to 4.6, and the system was allowed to stand for 30 min to allow some proteins and colloidal impurities to aggregate and settle. After standing, the system was centrifuged at 6000 r / min for 15 min, and the supernatant was collected to obtain a deproteinized β-glucan solution.

[0050] (4) The above deproteinized β-glucan solution was passed through a 100-mesh sieve and a 0.45 μm microfiltration membrane to remove insoluble fine particles and sedimented impurities, resulting in a clear β-glucan solution. The clear β-glucan solution was then concentrated by ultrafiltration using an ultrafiltration membrane with a molecular weight cutoff of 30 kDa. During ultrafiltration, an equal volume of water was added for washing when the solution was concentrated to 1 / 3 of its original volume, and this washing was repeated 3 times. After washing, the solution was further concentrated until the solid content was 8% to 10%, resulting in a concentrated β-glucan solution. Ethanol was added to the concentrated β-glucan solution to make the ethanol volume fraction in the system reach 75%. Stirring was maintained during the addition of alcohol at a speed of 100 r / min. After the addition of alcohol, the system was placed at 4°C and allowed to stand for 6 hours to allow the β-glucan to settle. - β-glucan precipitate; after settling, centrifuge at 6000 r / min for 15 min, collect the precipitate, and wash the precipitate twice with 75% ethanol aqueous solution to obtain wet β-glucan precipitate; add the above wet β-glucan precipitate to water, adjust the solid content to 12%, stir at 45℃ for 30 min, and then homogenize at a pressure of 20 MPa for 2 times to obtain β-glucan complex dispersion; dispense the β-glucan complex dispersion into freeze-drying pans, control the material layer thickness to 10 mm, and pre-freeze at -40℃ for 6 h; then freeze-dry under vacuum of 50 Pa for 24 h, after freeze-drying, pulverize and pass through an 80 mesh sieve to obtain oat β-glucan concentrate powder.

[0051] Since the 300kDa ultrafiltration membrane was not graded in this embodiment, the components with Mw≥300kDa and the components with 30kDa≤Mw<300kDa were not counted separately.

[0052] Example 2

[0053] It is basically the same as Example 1, except that:

[0054] The preparation method of the oat β-glucan concentrate powder is as follows:

[0055] (1) Take 100 kg of food-grade oat bran, remove coarse impurities by vibrating screen and remove metal foreign objects by magnetic separation, crush the oat bran after impurity removal and pass it through a 60-mesh sieve to obtain oat bran powder; spray water evenly into the oat bran powder to adjust the moisture content of the oat bran powder to 14%, and let it stand for 20 min to balance; then place the moisture-adjusted oat bran powder in a steam treatment device and steam treat it at 98℃ for 6 min; after the steam treatment, dry the oat bran powder with hot air at 50℃ until the moisture content is 7.5% to obtain pretreated oat bran powder;

[0056] (2) Take 100 kg of pretreated oat bran powder obtained in step (1), add 800 L of citrate-sodium citrate buffer solution with pH 5.6, stir evenly, heat to 45°C, pre-swell at 100 r / min for 15 min, then heat to 50°C, add ferulic acid esterase, the amount of ferulic acid esterase added is 0.025% of the weight of pretreated oat bran powder, treat at 50°C for 45 min, stirring speed is 120 r / min; after the reaction is completed, heat the system to 80°C and keep warm for 5 min to obtain enzymatic pretreated slurry; add to the above enzymatic pretreated slurry The pretreated oat bran powder was added to a eutectic solvent extract at a weight-to-volume ratio of 1 kg:10 L. The system temperature was controlled at 52 °C, and the extraction was carried out for 70 min with a stirring speed of 160 r / min. After extraction, the system was centrifuged at 5000 r / min for 15 min, and the supernatant was collected. Five times the weight of water was added to the precipitate, and the mixture was stirred and extracted at 45 °C for 20 min. After centrifugation, the supernatants from both extractions were combined to obtain a crude β-glucan extract.

[0057] (3) Heat the crude β-glucan extract obtained in step (2) to 82°C, adjust the pH to 6, add heat-resistant α-amylase at a rate of 0.06% of the weight of the pretreated oat bran powder, and keep it at this temperature for 25 min. Then, cool the system to 58°C, adjust the pH to 5, add pullulanase at a rate of 0.02% of the weight of the pretreated oat bran powder, and continue the treatment for 30 min. After the treatment is completed, take a sample to test the total starch content. After confirming that it is not higher than 0.5% on a dry basis, heat the system to 95°C. The enzyme was inactivated by heating at ℃ for 5 min to obtain a destarched solution. The destarched solution was then cooled to 50℃, the pH was adjusted to 6.5, and neutral protease was added at a rate of 0.05% of the weight of the pretreated oat bran powder. The solution was treated for 45 min. After treatment, the system was heated to 90℃ and incubated for 5 min to inactivate the enzyme. The pH was then adjusted to 4.6, and the solution was allowed to stand for 30 min. After standing, the solution was centrifuged at 6000 r / min for 15 min, and the supernatant was collected to obtain a deproteinized β-glucan solution.

[0058] (4) The above deproteinized β-glucan solution was passed through a 100-mesh sieve and a 0.45 μm microfiltration membrane sequentially to obtain a clear β-glucan solution; the clear β-glucan solution was first fractionated using an ultrafiltration membrane with a molecular weight cutoff of 300 kDa to obtain retentate A and permeate B; retentate A was washed and filtered using the 300 kDa ultrafiltration membrane, and an equal volume of water was added every time it was concentrated to 1 / 3 of its original volume, and the washing and filtration were repeated 4 times to obtain the medium-to-high molecular weight β-glucan component. The permeate from the washing filtration was combined with permeate B. The combined permeate was concentrated and washed using a 30 kDa ultrafiltration membrane. An equal volume of water was added each time the concentration reached 1 / 3 of the original volume, and the washing filtration was repeated four times. After washing, the concentration was continued until the solid content was 8% to 10%, yielding a low-to-medium molecular weight β-glucan component. The high-to-medium molecular weight β-glucan component and the low-to-medium molecular weight β-glucan component were mixed at a mass ratio of 7:3 to obtain a compound β-glucan concentrate. The above-mentioned compound β-glucan concentrate was then further concentrated. Ethanol was added to the β-glucan concentrate to make the ethanol volume fraction of the system reach 75%. Stirring was maintained during the ethanol addition process at a speed of 100 r / min. After the ethanol addition was completed, the system was allowed to stand at 4℃ for 6 h. After standing, the system was centrifuged at 6000 r / min for 15 min, the precipitate was collected, and washed twice with a 75% ethanol aqueous solution to obtain wet β-glucan precipitate. The wet β-glucan precipitate was added to water to adjust the solid content to 12%, and stirred at 45℃ for 30 min. Then, it was pre-homogenized once at 12 MPa and then finely homogenized once at 25 MPa to obtain a β-glucan complex dispersion. The β-glucan complex dispersion was dispensed into freeze-drying pans, with the material layer thickness controlled at 10 mm, and pre-frozen at -40℃ for 6 h. Then, it was freeze-dried under a vacuum of 50 Pa for 24 h. After freeze-drying, the powder was pulverized and passed through an 80-mesh sieve to obtain oat β-glucan concentrate powder. The method for preparing the eutectic solvent extract is as follows: weigh the raw materials according to the molar ratio of L-proline, gluconic acid and water of 1:1:10; first, add L-proline and gluconic acid to a preparation tank with stirring and temperature control functions, and stir at 60°C for 20 min; then add water and continue stirring at 60°C for 40 min to obtain the eutectic solvent mother liquor; dilute the eutectic solvent mother liquor with water so that the mass fraction of the eutectic solvent mother liquor in the eutectic solvent extract is 30% to obtain the eutectic solvent extract.

[0059] The yield was calculated as the percentage of the dry weight of each component relative to the dry weight of the pretreated oat bran powder, and the purity was calculated as the mass fraction of β-glucan in each component. The results were as follows: the yield of the medium-to-high molecular weight β-glucan component with Mw ≥ 300 kDa was 2.6%, and the purity was 93.8%; the yield of the medium-to-low molecular weight β-glucan component with 30 kDa ≤ Mw < 300 kDa was 1.1%, and the purity was 92.7%.

[0060] Example 3

[0061] It is basically the same as Example 2, except that in the preparation of oat β-glucan concentrate, the eutectic solvent extract is an aqueous solution of L-proline.

[0062] Specifically, pretreated oat bran powder was prepared according to the method in Example 2, and pretreated with ferulic acid esterase according to the method in Example 2 to obtain an enzymatic pretreatment slurry; an L-proline aqueous solution was prepared by mixing L-proline and water, wherein the molar amount of L-proline was the same as that of the L-proline in the eutectic solvent extract in Example 2; the above L-proline aqueous solution was added to the enzymatic pretreatment slurry, and the weight-to-volume ratio of pretreated oat bran powder to L-proline aqueous solution was controlled at 1 kg: 10 L, the system temperature was controlled at 52℃, the extraction was carried out for 70 min, and the stirring speed was 160 r / min; After completion, the system was centrifuged at 5000 r / min for 15 min, and the supernatant was collected. Five times the weight of water was added to the precipitate, and the mixture was stirred and extracted at 45°C for 20 min. After centrifugation, the supernatants from both extractions were combined to obtain crude β-glucan extract. The remaining steps of destarching, deproteinization, microfiltration, molecular weight fractionation and filtration with 300 kDa ultrafiltration membrane, concentration and filtration with 30 kDa combined permeate, compounding of medium and high molecular weight β-glucan components and medium and low molecular weight β-glucan components at a ratio of 7:3, alcohol precipitation, redisperfusion, homogenization, and freeze-drying were the same as in Example 2 to obtain oat β-glucan concentrate powder.

[0063] The same calculation and detection methods as in Example 2 were used for determination. The results were as follows: the yield of the component with Mw ≥ 300 kDa was 2.2%, and the purity was 92.0%; the yield of the component with 30 kDa ≤ Mw < 300 kDa was 0.9%, and the purity was 91.2%.

[0064] Example 4

[0065] It is basically the same as Example 2, except that in the preparation of oat β-glucan concentrate, the eutectic solvent is an aqueous solution of gluconic acid.

[0066] Specifically, pretreated oat bran powder was prepared according to the method of Example 2, and ferulic acid esterase pretreated it according to the method of Example 2 to obtain enzymatic hydrolysis pretreated slurry; gluconic acid and water were separately prepared into gluconic acid aqueous solution, wherein the molar amount of gluconic acid was the same as the molar amount of gluconic acid contained in the eutectic solvent extract in Example 2. Add the above gluconic acid aqueous solution to the enzymatic hydrolysis pretreatment slurry, controlling the weight-to-volume ratio of pretreated oat bran powder to gluconic acid aqueous solution to be 1 kg: 10 L. Control the system temperature at 52℃, extract for 70 min, and stir at 160 r / min. After extraction, centrifuge the system at 5000 r / min for 15 min and collect the supernatant. Add 5 times the weight of water to the precipitate, stir and extract at 45℃ for 20 min, centrifuge, and combine the two supernatants to obtain crude β-glucan extract. The remaining steps of destarching, deproteinization, microfiltration, molecular weight fractionation and filtration of 300 kDa ultrafiltration membrane and filtration of retentate, concentration and filtration of 30 kDa combined permeate, compounding of medium and high molecular weight β-glucan components and medium and low molecular weight β-glucan components at a ratio of 7:3, alcohol precipitation, redispermia, homogenization, and freeze drying are the same as in Example 2 to obtain oat β-glucan concentrate.

[0067] The same calculation and detection methods as in Example 2 were used for determination. The results were as follows: the yield of the component with Mw ≥ 300 kDa was 2.3%, and the purity was 92.4%; the yield of the component with 30 kDa ≤ Mw < 300 kDa was 1%, and the purity was 91.8%.

[0068] Comparative Example 1

[0069] The process is basically the same as in Example 2, except that: in the preparation of oat β-glucan concentrate, ferulic acid esterase pretreatment is not performed, and eutectic solvent extraction is not used.

[0070] Specifically, 100 kg of pretreated oat bran powder was taken, 1000 L of water was added, and the mixture was stirred evenly. The pH was adjusted to 6.2, and the mixture was extracted at 60 °C for 90 min with a stirring speed of 160 r / min. After extraction, the mixture was centrifuged at 5000 r / min for 15 min, and the supernatant was collected. Five times the weight of water was added to the precipitate, and the mixture was stirred and extracted at 45 °C for 20 min. After centrifugation, the supernatants from both extractions were combined to obtain crude β-glucan extract. The remaining steps of destarching, deproteinization, microfiltration, 300 kDa molecular weight fractionation and filtration with the retentate, 30 kDa combined permeate concentration and filtration, 7:3 compounding, alcohol precipitation, redispermia, gradient homogenization, and freeze-drying were the same as in Example 2 to obtain oat β-glucan concentrate powder.

[0071] The same calculation and detection methods as in Example 2 were used for determination. The results were as follows: the yield of the component with Mw ≥ 300 kDa was 1.7% and the purity was 89.1%; the yield of the component with 30 kDa ≤ Mw < 300 kDa was 0.7% and the purity was 88.3%.

[0072] Comparative Example 2

[0073] The process is basically the same as in Example 2, except that: in the preparation of oat β-glucan concentrate powder, ferulic acid esterase pretreatment is not performed, and only eutectic solvent extraction is used.

[0074] Specifically: 100 kg of pretreated oat bran powder was taken and added to 800 L of citrate-sodium citrate buffer solution with a pH of 5.6. The mixture was pre-swelled at 45°C and 100 rpm for 15 min, then heated to 50°C and held for 45 min with a stirring speed of 120 rpm. Subsequently, the temperature was raised to 80°C and held for 5 min to obtain an enzyme-free pretreated slurry. A eutectic solvent extract was added to the enzyme-free pretreated slurry. The eutectic solvent extract was prepared with a molar ratio of L-proline, gluconic acid, and water of 1:1:10 and diluted with water to a eutectic solvent mother liquor mass fraction of 30%. The weight-to-volume ratio of pretreated oat bran powder to eutectic solvent extract was controlled at 1 kg / kg. The extract was prepared at 10 L g / L and extracted at 52 °C for 70 min with a stirring speed of 160 r / min. After extraction, the extract was centrifuged at 5000 r / min for 15 min and the supernatant was collected. Five times the weight of water was added to the precipitate and the extract was stirred and extracted at 45 °C for 20 min. After centrifugation, the supernatants from both extractions were combined to obtain crude β-glucan extract. The remaining steps of destarching, deproteinization, microfiltration, 300 kDa molecular weight fractionation and filtration with the cut-off liquid, 30 kDa combined permeate concentration and filtration, 7:3 compounding, alcohol precipitation, redispermia, gradient homogenization and freeze drying were the same as in Example 2 to obtain oat β-glucan concentrate powder.

[0075] The same calculation and detection methods as in Example 2 were used for determination. The results were as follows: the yield of the component with Mw ≥ 300 kDa was 2.2%, and the purity was 92.6%; the yield of the component with 30 kDa ≤ Mw < 300 kDa was 0.9%, and the purity was 91.8%.

[0076] Comparative Example 3

[0077] The process is basically the same as in Example 2, except that: in the preparation of oat β-glucan concentrate, ferulic acid esterase pretreatment is performed, but eutectic solvent extraction is not used.

[0078] Specifically: Take 100 kg of pretreated oat bran powder, add 800 L of citrate-sodium citrate buffer solution with pH 5.6, stir evenly, and heat to 45°C. Pre-swell at 100 r / min for 15 min, then heat to 50°C and add ferulic acid esterase at a concentration of 0.025% of the weight of the pretreated oat bran powder. Treat at 50°C for 45 min with a stirring speed of 120 r / min. After the reaction, heat the system to 80°C and hold for 5 min to obtain the enzymatically hydrolyzed pretreated slurry. Add water to the above enzymatically hydrolyzed pretreated slurry to make the weight-volume ratio of pretreated oat bran powder to water 1 kg: 10 L, and treat at 52°C. Extract for 70 min at a stirring speed of 160 r / min; after extraction, centrifuge at 5000 r / min for 15 min and collect the supernatant; add 5 times the weight of water to the precipitate and extract at 45℃ for 20 min with stirring, centrifuge and combine the two supernatants to obtain crude β-glucan extract; the remaining steps of destarching, deproteinization, microfiltration, 300 kDa molecular weight fractionation and filtration with retentate, 30 kDa combined permeate concentration and filtration, 7:3 compounding, alcohol precipitation, redispermia, gradient homogenization and freeze drying are the same as in Example 2 to obtain oat β-glucan concentrate powder.

[0079] The same calculation and detection methods as in Example 2 were used for determination. The results were as follows: the yield of the component with Mw ≥ 300 kDa was 2%, and the purity was 90.6%; the yield of the component with 30 kDa ≤ Mw < 300 kDa was 0.8%, and the purity was 89.7%.

[0080] Comparative Example 4

[0081] The process is basically the same as in Example 2, except that in the preparation of oat β-glucan concentrate, the eutectic solvent is an equal amount of citric acid-sodium citrate buffer solution with a pH of 5.6.

[0082] Specifically: Take 100 kg of pretreated oat bran powder, add 800 L of citrate-sodium citrate buffer solution with pH 5.6, stir evenly, and heat to 45℃. Pre-swell at 100 r / min for 15 min, then heat to 50℃. Add ferulic acid esterase at a concentration of 0.025% of the weight of the pretreated oat bran powder. Treat at 50℃ for 45 min with a stirring speed of 120 r / min. After the reaction, heat the system to 80℃ and hold for 5 min to obtain the enzymatically hydrolyzed pretreated slurry. Add citrate-sodium citrate buffer solution with pH 5.6 to the above enzymatically hydrolyzed pretreated slurry. An acid-sodium citrate buffer solution was used to prepare a liquid phase system with a weight-to-volume ratio of 1 kg:10 L of pretreated oat bran powder. Extraction was performed at 52°C for 70 min with a stirring speed of 160 rpm. After extraction, the mixture was centrifuged at 5000 rpm for 15 min, and the supernatant was collected. Five times the weight of water was added to the precipitate, and extraction was carried out at 45°C with stirring for 20 min. After centrifugation, the supernatants from both extractions were combined to obtain a crude β-glucan extract. The remaining steps were the same as in Example 2 to obtain oat β-glucan concentrate. The same calculation and detection methods as in Example 2 were used for determination. The results showed that the yield of the component with Mw ≥ 300 kDa was 1.9%, and the purity was 90.1%; the yield of the component with 30 kDa ≤ Mw < 300 kDa was 0.8%, and the purity was 89.4%.

[0083] Comparative Example 5

[0084] The process is basically the same as in Example 2, except that in the preparation of oat β-glucan concentrate, ferulic acid esterase is not pretreated in the buffer solution, but is added at the same time as the eutectic solvent.

[0085] Specifically: Take 100 kg of pretreated oat bran powder, add 800 L of citrate-sodium citrate buffer solution with a pH of 5.6, and add eutectic solvent extraction solution, controlling the weight-to-volume ratio of pretreated oat bran powder to eutectic solvent extraction solution to be 1 kg: 10 L; then add ferulic acid esterase at a concentration of 0.025% of the weight of pretreated oat bran powder, and simultaneously enzymatically hydrolyze and extract at 52℃ for 70 min with a stirring speed of 160 r / min; after extraction, raise the system temperature to 80℃ and hold for 5 min, then stir at 5000 r / min. Centrifuge at 15 min for 15 min and collect the supernatant; add 5 times the weight of water to the precipitate and extract by stirring at 45℃ for 20 min. After centrifugation, combine the supernatants from both extractions to obtain crude β-glucan extract; the remaining steps of destarching, deproteinization, microfiltration, 300 kDa molecular weight fractionation and filtration with the cut-off liquid, 30 kDa combined permeate concentration and filtration, 7:3 compounding, alcohol precipitation, redispersibility, gradient homogenization, and freeze-drying are the same as in Example 2 to obtain oat β-glucan concentrate. The same calculation and detection methods as in Example 2 were used for determination. The results were: the yield of the component with Mw ≥ 300 kDa was 2.4%, and the purity was 93%; the yield of the component with 30 kDa ≤ Mw < 300 kDa was 1%, and the purity was 92.1%.

[0086] Comparative Example 6

[0087] The process is basically the same as in Example 2, except that the two β-glucan components after molecular weight fractionation are not subjected to ultrafiltration washing during the preparation of oat β-glucan concentrate powder.

[0088] Specifically, the clarified β-glucan solution obtained by microfiltration in Example 2 was fractionated using a 300kDa ultrafiltration membrane to obtain retentate A and permeate B. Retentate A was not washed, while permeate B was directly concentrated using a 30kDa ultrafiltration membrane to a solid content of 8% to 10% without water washing. Subsequently, the mixture was compounded in a 7:3 ratio, precipitated with alcohol, redispersed, homogenized in a gradient, and freeze-dried according to the method in Example 2 to obtain oat β-glucan concentrate powder. The remaining steps were the same as in Example 2. The same calculation and detection methods as in Example 2 were used for determination, and the results were as follows: the yield of the component with Mw ≥ 300kDa was 2.8%, and the purity was 86.5%; the yield of the component with 30kDa ≤ Mw < 300kDa was 1.3%, and the purity was 84.9%.

[0089] Comparative Example 7

[0090] The process is basically the same as Example 2, except that: in the preparation of oat β-glucan concentrate powder, no 300kDa ultrafiltration membrane molecular weight classification is performed, and no 7:3 blending of medium and high molecular weight β-glucan components and medium and low molecular weight β-glucan components is performed.

[0091] Specifically, the clarified β-glucan solution obtained by microfiltration in Example 2 was directly concentrated and washed using a 30kDa ultrafiltration membrane to obtain a β-glucan concentrate with a solid content of 8% to 10%, without molecular weight fractionation using a 300kDa ultrafiltration membrane or blending of high-molecular-weight and low-molecular-weight components; then, ethanol precipitation, redispersion, gradient homogenization, and freeze-drying were performed directly to obtain oat β-glucan concentrate powder; the remaining steps were the same as in Example 2.

[0092] Comparative Example 8

[0093] The process is basically the same as in Example 2, except that in the preparation of oat β-glucan concentrate, after fractionation by a 300kDa ultrafiltration membrane, the medium-to-high molecular weight β-glucan components and the medium-to-low molecular weight β-glucan components are mixed at a mass ratio of 9:1 instead of 7:3; the remaining steps are the same as in Example 2, and oat β-glucan concentrate is obtained.

[0094] Comparative Example 9

[0095] The process is basically the same as in Example 2, except that in the preparation of oat β-glucan concentrate, after fractionation by a 300kDa ultrafiltration membrane, the medium-to-high molecular weight β-glucan components and the medium-to-low molecular weight β-glucan components are mixed at a mass ratio of 5:5 instead of 7:3; the remaining steps are the same as in Example 2, and oat β-glucan concentrate is obtained.

[0096] Test Example 1

[0097] Take 35g of the oat bran composition from both the example and comparative examples, add it to 180mL of hot water at 85℃, stir manually for 15s, let stand for 30s, and observe the mixing state. Pass the mixed sample through a 10-mesh sieve, collect the undispersed wet clumps on the sieve, and dry them at 60℃ to constant weight. Calculate the agglomeration rate based on the percentage of the mass of the dried clumps relative to the total amount of sample added.

[0098] After rehydration, the sample was allowed to stand for 2 minutes, and its viscosity was measured using a rotational viscometer at 55°C with a rotor speed of 30 r / min. Each sample was measured in triplicate, and the average value was taken.

[0099] Pour the prepared sample into a 100mL graduated cylinder, let it stand for 10 minutes, observe the volume of the supernatant layer, and calculate the suspension stability using the following formula:

[0100] Suspension stability rate = (total volume - volume of supernatant separation) / total volume × 100%.

[0101] Ten trained evaluators were selected to conduct blind evaluations of each group of samples using random three-digit codes. They scored the samples on clumping, viscosity, smoothness, and layering. Each evaluation item had a maximum score of 2.5 points, and the sum of the four scores was the evaluator's overall score, with a maximum of 10 points. The sensory score for each group of samples was the arithmetic mean of the overall scores from the ten evaluators; a higher score indicated better mixing. The specific scoring criteria are shown in the table below.

[0102] Table 1. Specific Scoring Criteria for Sensory Evaluation

[0103] Powder situation 0-2.5 points 2.1-2.5 points: No visible wet lumps, and virtually no residue after passing through a 10-mesh sieve; 1.1-2 points: A small number of soft lumps with a particle size no larger than 3mm are present, which can be dispersed by slight stirring; 0-1 points: A large number of wet lumps or particles larger than 3mm are present, which are still obvious after stirring. viscosity 0-2.5 points 2.1-2.5 points: Moderate consistency, continuous flow, no obvious pasty or watery texture; 1.1-2 points: Slightly thick or slightly thin, but generally acceptable; 0-1 point: Too thick to flow, or too thin to have consistency, significantly affecting the eating experience. Smoothness 0-2.5 points 2.1-2.5 points: Smooth and delicate on the palate, with no obvious graininess, stickiness or astringency; 1.1-2 points: Slight graininess or stickiness exists, but it is generally acceptable; 0-1 point: Obvious roughness, graininess, stickiness or astringency. Layering 0-2.5 points 2.1-2.5 points: No obvious supernatant or sedimentation after standing for 10 minutes; 1.1-2 points: Slight supernatant or sedimentation appears, which can be restored to homogeneity after shaking; 0-1 point: Obvious stratification or sedimentation appears, which is difficult to restore to homogeneity after shaking.

[0104] The test results are shown in Table 2.

[0105] Table 2. Reconstituteability of Oat Bran Compositions

[0106] Example 1 6.9 1540 87.6 7.1 Example 2 1 1860 96.8 9.2 Example 3 5.5 1640 90.2 7.6 Example 4 5 1670 91 7.8 Comparative Example 1 8.6 1460 84.6 6.5 Comparative Example 2 4.8 1700 91.6 7.9 Comparative Example 3 6.3 1560 88 7 Comparative Example 4 6 1580 88.5 7.1 Comparative Example 5 3.5 1740 93.2 8.3 Comparative Example 6 2.4 1810 94.6 7.4 Comparative Example 7 3.9 1780 91.8 8 Comparative Example 8 2.8 2240 96.2 7.8 Comparative Example 9 1.8 1320 88.7 7.6

[0107] As shown in Table 2, the oat bran composition prepared in Example 2 had the lowest caking rate, a suitable viscosity, and the highest suspension stability and sensory score. In Example 2, ferulic acid esterase was used to cleave some of the ferulic acid ester crosslinks in the oat bran cell walls. Then, a eutectic hydrogen bond network formed by L-proline, gluconic acid, and water was used to promote cell wall swelling and β-glucan release. Low-molecular-weight impurities were removed by ultrafiltration. The resulting high-molecular-weight components were blended with low-molecular-weight components in a 7:3 ratio, forming a continuous but not excessively thickened hydration network in hot water. Therefore, the caking rate was 1%, the viscosity was 1860 mPa·s, and the suspension stability was 96.8%, exhibiting both a smooth texture and low stratification. In Example 1, conventional water extraction was used without 300 kDa molecular weight fractionation, resulting in insufficient β-glucan release, impurity entrainment, and a wider molecular weight distribution, leading to uneven hydration, increased caking rate, and decreased suspension stability. Examples 3 and 4 used only L-proline aqueous solution or gluconic acid aqueous solution, respectively, and did not form a complete eutectic hydrogen bond network. Therefore, their solvation and deconstruction effects on the cell wall complex structure were weaker than in Example 2, and their performance indicators were between those of Examples 1 and 2. Comparative Example 1 lacked both ferulic acid esterase pretreatment and eutectic solvent extraction, resulting in the most significant β-glucan embedding within the cell wall, the highest agglomeration rate, and the lowest suspension stability and sensory score. Comparative Example 2 lacked enzymatic pre-crosslinking, Comparative Example 3 lacked the subsequent swelling and solvation effects of the eutectic solvent, and Comparative Example 4 used buffer instead of the eutectic solvent, all of which failed to fully release the deeply embedded β-glucan. Comparative Example 5 added ferulic acid esterase and the eutectic solvent simultaneously, affecting the contact between the enzyme and the crosslinking sites and the degree of pre-crosslinking, thus its performance was lower than that of Example 2. Comparative Example 6 did not undergo ultrafiltration washing. Although the residual small molecules could produce a certain wetting effect, seemingly improving the agglomeration rate and suspension stability, it also increased hygroscopicity and acidity and aftertaste, resulting in a sensory score of only 7.4. Comparative Example 7 did not undergo 300kDa molecular weight classification and fixed-ratio blending, and the wide molecular weight distribution caused inconsistencies in local hydration rates and viscosity. In Comparative Example 8, the proportion of high molecular weight components was increased to 9:1, increasing the viscosity to 2240 mPa·s, resulting in higher suspension stability but an overly thick mouthfeel. In Comparative Example 9, the proportion of low molecular weight components was increased to 5:5, resulting in faster initial dispersion and a lower agglomeration rate, but the viscosity dropped to 1320 mPa·s, making it difficult to form a stable suspended network. Therefore, the suspension stability and overall sensory score were lower than those of Example 2.

[0108] Test Example 2

[0109] The oat bran compositions prepared in the examples and comparative examples were used as test samples. Each sample was added to the in vitro fermentation system in the same amount.

[0110] Fresh stool samples were collected from three healthy subjects. Subjects had not taken antibiotics, probiotics, or laxatives within two weeks prior to sampling, and informed consent was obtained from all subjects. Each stool sample was mixed with sterile phosphate buffer at a mass ratio of 1:9 under anaerobic conditions, filtered, and a fecal microbiota suspension was obtained.

[0111] The basic fermentation medium consists of 2 g / L peptone, 2 g / L yeast extract, 0.1 g / L sodium chloride, 0.04 g / L dipotassium hydrogen phosphate, 0.04 g / L potassium dihydrogen phosphate, 0.01 g / L magnesium sulfate, 0.01 g / L calcium chloride, 2 g / L sodium bicarbonate, 0.5 g / L bile salts, 0.5 g / L L-cysteine ​​hydrochloride, and 1 mg / L resazurin, sterilized for later use.

[0112] Each anaerobic fermentation bottle was filled with 45 mL of basal fermentation medium, 5 mL of fecal microbial suspension, and 1 g of the oat bran composition to be tested. The experiment included a blank group, Examples 1-4, and Comparative Examples 1-9. The blank group did not contain the oat bran composition. Each fermentation bottle was sealed after being purged with nitrogen to remove oxygen, and anaerobic fermentation was carried out at 37°C for 24 h. Three replicates were prepared for each group.

[0113] After fermentation, the fermentation broth was centrifuged, and the supernatant was filtered through a 0.22 μm filter membrane. The contents of acetic acid, propionic acid, and butyric acid were determined by gas chromatography. Standard curves were established using acetic acid, propionic acid, and butyric acid standards, and the contents of each short-chain fatty acid were calculated.

[0114] The test results are shown in Table 3.

[0115] Table 3. Short-chain fatty acid content after 24 hours of in vitro fermentation

[0116] Blank group 12.6 4.8 3.1 20.5 Example 1 25.8 9.4 7.6 42.8 Example 2 31.5 11.6 9.8 52.9 Example 3 27.6 10.1 8.5 46.2 Example 4 28.2 10.3 8.6 47.1 Comparative Example 1 24 8.9 6.7 39.6 Comparative Example 2 26.7 9.8 7.6 44.1 Comparative Example 3 25.8 9.5 7.4 42.7 Comparative Example 4 26 9.6 7.6 43.2 Comparative Example 5 29 10.6 8.6 48.2 Comparative Example 6 27.1 9.9 8 45 Comparative Example 7 28.3 10.4 8.6 47.3 Comparative Example 8 28.7 10.5 8.8 48 Comparative Example 9 30.1 11 9.1 50.2

[0117] As shown in Table 3, Example 2 exhibited the highest total short-chain fatty acid content after 24 hours of in vitro fermentation. This is because Example 2 improved the β-glucan release rate and obtained β-glucan components with both medium-high and medium-low molecular weights through molecular weight fractionation. The medium-high molecular weight components are beneficial for maintaining the dispersion stability of the composition, while the medium-low molecular weight components are more easily accessed and utilized by intestinal flora, thus increasing the production of acetic acid, propionic acid, and butyric acid. Examples 3-4 and Comparative Examples 1-4 had lower substrate accessibility than Example 2 due to insufficient β-glucan release or limited deconstruction capacity of the extraction system. Although Comparative Example 5 used ferulic acid esterase and a eutectic solvent simultaneously, the simultaneous addition weakened the enzymatic pretreatment effect, resulting in a lower short-chain fatty acid production than Example 2. Comparative Example 6 may have affected the stability of the fermentation system due to insufficient removal of small molecule residues from the eutectic solvent. Comparative Example 7 did not undergo molecular weight fractionation, resulting in uneven substrate accessibility. Comparative Example 8 had an excessively high proportion of high molecular weight components, resulting in a high system viscosity and limited substrate diffusion. Comparative Example 9 had a relatively high proportion of low molecular weight components, and its fermentation effect was close to that of Example 2, but its reconstitution and suspension stability was insufficient, and its overall performance was still lower than that of Example 2.

[0118] Test Example 3

[0119] Fifty-six SPF-grade male SD rats, weighing 180-220g, were selected and randomly divided into four groups (n=8 per group) after 7 days of acclimatization: normal group, model group, Example 1 group, Example 2 group, Comparative Example 7 group, Comparative Example 8 group, and Comparative Example 9 group. The experiment was conducted in accordance with ethical requirements for laboratory animals.

[0120] The control group was fed a basal diet, while the other groups were fed a high-fat diet. After two weeks of continuous feeding, elevated serum total cholesterol and low-density lipoprotein cholesterol were confirmed by tail vein blood sampling in the model animals. Subsequently, the sample groups continued to be fed a high-fat diet and were administered an aqueous dispersion of the corresponding oat bran composition by gavage daily at a dose of 3.5 g / kg body weight; the control group and the model group were administered an equal volume of water by gavage daily for six consecutive weeks.

[0121] Students fasted for 12 hours before the end of the experiment. Blood was collected and serum was separated. Serum total cholesterol, triglycerides, low-density lipoprotein cholesterol, and high-density lipoprotein cholesterol were measured using a fully automated biochemical analyzer and accompanying reagent kits. Results for each group are expressed as mean ± standard deviation. The test results are shown in Table 4.

[0122] Table 4. Results of lipid-regulating function test of oat bran composition

[0123] normal group 1.72±0.15 0.71±0.08 0.47±0.06 1.11±0.09 Model group 3.61±0.28 1.54±0.17 2.31±0.22 0.69±0.07 Example 1 2.94±0.24 1.27±0.13 1.74±0.18 0.81±0.08 Example 2 2.32±0.2 1.01±0.11 1.20±0.14 0.98±0.09 Comparative Example 7 2.81±0.23 1.19±0.12 1.62±0.16 0.85±0.08 Comparative Example 8 2.45±0.21 1.09±0.1 1.31±0.15 0.93±0.09 Comparative Example 9 2.71±0.22 1.13±0.11 1.50±0.16 0.89±0.08

[0124] Table 4 shows that serum total cholesterol, triglycerides, and low-density lipoprotein cholesterol increased, while high-density lipoprotein cholesterol decreased in the high-lipid model group, indicating successful model establishment. Lipid indicators in all sample groups showed varying degrees of improvement. In Example 2, total cholesterol and low-density lipoprotein cholesterol were lower, indicating that molecular weight fractionation and compounding are beneficial for improving the lipid-regulating effect of the composition. In Example 2, medium- and high molecular weight β-glucan could form suitable viscosity, reducing cholesterol absorption and promoting bile acid excretion; medium- and low molecular weight β-glucan were more easily utilized by intestinal flora, and its fermentation products helped improve lipid metabolism. Comparative Example 7 did not undergo molecular weight fractionation, resulting in a wider component distribution; Comparative Example 8 had an excessively high proportion of high molecular weight components, affecting dispersion and hydration; Comparative Example 9 had a high proportion of low molecular weight components, resulting in insufficient viscosity contribution. Therefore, the overall lipid-regulating effect of all three was lower than that of Example 2.

[0125] The preferred embodiments of the present invention have been described in detail above. It should be understood that those skilled in the art can make numerous modifications and variations based on the concept of the present invention without creative effort. Therefore, all technical solutions that can be obtained by those skilled in the art based on the concept of the present invention through logical analysis, reasoning, or limited experimentation on the basis of existing technology should be within the scope of protection defined by the claims.

Claims

1. An oat bran composition for regulating intestinal flora, characterized in that: By weight, it includes the following components: 45-70 parts oat bran, 3-10 parts oat β-glucan concentrate, 3-12 parts tremella powder, 2-10 parts inulin, 2-8 parts resistant dextrin, 1-5 parts fructooligosaccharides, 2-10 parts soybean flour, 2-8 parts coconut milk powder, 0.5-5 parts jujube powder, and 0.5-3 parts goji berry powder; The oat β-glucan concentrate is prepared by a method comprising the following steps: pretreating oat bran powder with ferulic acid esterase to obtain an enzymatically hydrolyzed pretreated slurry; extracting the enzymatically hydrolyzed pretreated slurry with a eutectic solvent extract to obtain a crude β-glucan extract; subjecting the crude β-glucan extract to destarch removal, deproteinization, clarification, molecular weight fractionation, ultrafiltration, alcohol precipitation, redispersibility, homogenization, and freeze-drying to obtain oat β-glucan concentrate.

2. The oat bran composition for regulating intestinal flora as described in claim 1, characterized in that: By weight, it includes the following components: 52-64 parts oat bran, 4-8 parts oat β-glucan concentrate, 5-10 parts tremella powder, 4-8 parts inulin, 3-7 parts resistant dextrin, 2-4 parts fructooligosaccharides, 4-8 parts soybean flour, 3-6 parts coconut milk powder, 1-3 parts jujube powder, and 0.5-2 parts goji berry powder.

3. The oat bran composition for regulating intestinal flora as described in claim 1, characterized in that: The eutectic solvent extract is obtained by diluting a eutectic solvent mother liquor with water. The eutectic solvent mother liquor is composed of a hydrogen bond acceptor, a hydrogen bond donor, and water. The hydrogen bond acceptor is selected from one or more of L-proline, betaine, L-carnitine, choline acetate, and glycine. The hydrogen bond donor is selected from one or more of gluconic acid, L-malic acid, lactic acid, L-tartaric acid, succinic acid, and citric acid.

4. The oat bran composition for regulating intestinal flora as described in claim 1, characterized in that: The ferulic acid esterase pretreatment is as follows: pretreated oat bran powder is added to a citrate-sodium citrate buffer solution with a pH of 5-6.2, and the weight-to-volume ratio of the pretreated oat bran powder to the citrate-sodium citrate buffer solution is 1 kg: (6-10) L; pre-swelling is carried out at 45-50℃ and 60-120 r / min for 10-20 min, then the temperature is adjusted to 45-55℃ and ferulic acid esterase is added, with the amount of ferulic acid esterase added being 0.01-0.06% of the weight of the pretreated oat bran powder, and treatment is carried out at 45-55℃ for 20-90 min. After the treatment, the temperature is raised to 80-90℃ and kept at that temperature for 5-10 min to obtain the enzymatically hydrolyzed pretreated slurry.

5. The oat bran composition for regulating intestinal flora as described in claim 1, characterized in that: The extraction of the enzymatically pretreated slurry using a eutectic solvent extract is as follows: Eutectic solvent extract is added to the enzymatically pretreated slurry, and the weight-to-volume ratio of pretreated oat bran powder to eutectic solvent extract is controlled at 1 kg: (8-15) L. Extraction is carried out at 45-60℃ for 40-120 min. After extraction, centrifugation is performed, and the supernatant is collected. 3-8 times the weight of water is added to the precipitate, and extraction is carried out at 40-50℃ with stirring for 10-40 min. After centrifugation, the supernatants are combined to obtain a crude β-glucan extract.

6. The oat bran composition for regulating intestinal flora as described in claim 1, characterized in that: The molecular weight fractionation and ultrafiltration washing are as follows: the clarified β-glucan solution is first fractionated using an ultrafiltration membrane with a molecular weight cutoff of 200-500 kDa to obtain retentate A and permeate B; retentate A is washed using the 200-500 kDa ultrafiltration membrane, and when it is concentrated to 1 / 2-1 / 4 of its original volume, an equal volume of water is added, and the washing is repeated 2-6 times to obtain medium-to-high molecular weight β-glucan components, and the permeate generated from the washing is combined with the permeate B.

7. The oat bran composition for regulating intestinal flora as described in claim 6, characterized in that: The combined permeate was concentrated and washed using an ultrafiltration membrane with a molecular weight cutoff of 20-50 kDa. When the volume was reduced to 1 / 2-1 / 4 of the original volume, an equal volume of water was added, and the washing and filtration were repeated 2-6 times. After washing and filtration, the concentration was continued until the solid content was 6-12% to obtain the medium and low molecular weight β-glucan component. The medium and high molecular weight β-glucan component and the medium and low molecular weight β-glucan component were mixed at a mass ratio of (6-8):(2-4) to obtain a compound β-glucan concentrate.

8. The method for preparing the oat bran composition for regulating intestinal flora as described in any one of claims 1-7, characterized in that, Includes the following steps: S1. Take oat bran, remove impurities and place it in a steam cooking device, treat it at 90-100℃ for 8-20 minutes; then dry it with hot air at 45-65℃ until the moisture content is no more than 6.5%, pulverize it and pass it through a 60-100 mesh sieve to obtain pretreated oat bran. S2. Take dried white fungus, remove impurities, soak in water for 1-4 hours, drain, and steam at 95-105℃ for 20-60 minutes; pre-freeze the steamed white fungus at -25℃ to -45℃ for 4-10 hours, then freeze-dry at a vacuum degree not higher than 80Pa for 12-30 hours, pulverize and pass through a 60-100 mesh sieve to obtain white fungus powder. S3. Add oat β-glucan concentrate, inulin, resistant dextrin and oligofructose to a mixer and mix at 10-30 r / min for 5-20 min to obtain a compound dietary fiber premix. S4. Add the pretreated oat bran, tremella powder and compound dietary fiber premix to the mixing equipment and mix for 10-25 minutes; then add soybean powder, coconut milk powder, red date powder and goji berry powder and continue mixing for 5-20 minutes to obtain the initial mixture; S5. Spray water into the initial mixture, the amount of water being 3-8% of the total weight of the initial mixture, the spraying pressure being 0.1-0.4 MPa, and stirring while spraying, so that the powder forms loose particles with a particle size of 0.2-1.5 mm; pre-freeze the loose particles at -25℃ to -45℃ for 4-10 h, and then freeze-dry them at a vacuum degree not exceeding 80 Pa for 12-30 h to obtain the oat bran composition; S6. The oat bran composition is packaged with nitrogen, and the oxygen content of the packaging is controlled to be below 3%.