A method for extracting oat beta-glucan
By combining ultrasonic treatment with heat-resistant α-amylase and ethanol precipitation, the problem of enzyme activity removal during oat β-glucan extraction was solved, achieving a highly efficient and rapid extraction process with concentrated product purity and molecular weight, and strong free radical scavenging ability.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- JIANGSU AGRI ANIMAL HUSBANDRY VOCATIONAL COLLEGE
- Filing Date
- 2026-04-30
- Publication Date
- 2026-06-16
AI Technical Summary
Existing methods for extracting oat β-glucan suffer from difficulties in effectively removing enzyme activity, resulting in a cumbersome extraction process that damages molecular integrity, requires large amounts of solvent, and involves complex processing steps.
Ultrasonic treatment combined with heat-resistant α-amylase treatment was employed. The ultrasonic mode was set at 300W, with each ultrasonic treatment lasting 2-3 seconds followed by a 2-3 second interval. Subsequently, centrifugation and ethanol precipitation were performed, followed by freeze-drying to obtain oat β-glucan. Finally, the extraction process was optimized by hydrochloric acid degradation.
Rapid and efficient extraction of oat β-glucan was achieved, with a product purity of up to 67.52%, concentrated molecular weight, and strong DPPH free radical scavenging ability.
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Figure CN122213271A_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of food technology, specifically relating to a method for extracting oat β-glucan. Background Technology
[0002] Whether the goal is commercial development or scientific investigation, the aim is usually to extract β-glucan by maximizing the use of existing resources for further application or research. Generally, this should not come at the expense of molecular integrity; in other words, the natural structure and molecular weight (Mw) should be preserved as much as possible. Obviously, the natural cell wall macromolecules and quaternary structures cannot be preserved during extraction, but retaining all major structural features and maximizing the molecular weight is a reasonable objective.
[0003] The activity of exogenous β-glucanase and its degree of hydrolysis in solution during extraction are important factors affecting the structure and content of the extract. During extraction and separation, the greatest threat to depolymerization comes from enzyme activity. Cereal β-glucan is easily affected by cellulase, and cellulase-producing organisms are ubiquitous in the environment. Microorganisms and their enzymes exist in harvested raw grains, regardless of whether the grains themselves contain endogenous enzymes. The standard procedure for inactivating enzyme activity in the laboratory is reflux in an ethanol-water solution. Refluxing raw bran in 80% ethanol for about 2 hours inactivates β-glucanase. After reflux treatment, adding a heat-resistant amylase to the sample during extraction results in a relatively pure β-glucan sample.
[0004] Therefore, existing reports on the extraction of oat β-glucan mainly involve first inactivating the enzyme and defatting it with ethanol, followed by extraction with different solvents (water, acidic buffer, alkaline solution, dimethyl sulfoxide, etc.). However, the extraction of oat β-glucan using hot water with stirring within a pH range of 7-10 requires a long time, a large amount of solvent, and complicated processing steps. Summary of the Invention
[0005] The purpose of this invention is to overcome the above-mentioned shortcomings and provide a mild, rapid and efficient method for extracting oat β-glucan.
[0006] The objective of this invention is achieved through the following means: (1) Crush the oat bran through a 60-80 mesh sieve, then add water at a material-to-liquid ratio of 1:6-8 and slurry it. Let it stand for 1-2 hours. Then, ultrasonically treat it for 10-15 minutes under a 60℃ circulating water bath. The ultrasonic treatment mode is: power 300W, ultrasonic treatment for 2-3 seconds and interval for 2-3 seconds.
[0007] (2) After sonication, the suspension was centrifuged twice, the supernatants were combined, and heat-resistant α-amylase was added until the starch did not turn blue. Then the suspension was cooled to room temperature, the pH of the solution was adjusted to 4.5, and the suspension was left to stand overnight at 4°C. The resulting suspension was centrifuged at 3000 r / min for 10-15 min, the supernatant was collected, the pH was adjusted to 7.0, the suspension was concentrated to 1 / 3 of the original volume, 30% ethanol solution was added, and the suspension was left to stand overnight at 4°C. The suspension was then centrifuged at 6000 rpm for 10-15 min, the precipitate was collected, the precipitate was reconstituted with water, and the precipitate was freeze-dried to obtain oat β-glucan.
[0008] Preferably, in step (1), water is added at a ratio of 1:6 to make pulp.
[0009] Preferably, the oat bran described in step (1) is washed, dried to a moisture content of 12-13%, and then pulverized. Most preferably, it is dried to a moisture content of 12.8% and then pulverized.
[0010] Preferably, the suspension is centrifuged twice in step (2), specifically at a centrifugation speed of 3000 r / min each time, and for a centrifugation time of 10-15 min each time.
[0011] The oat β-glucan extracted by the above method was subjected to acid degradation. The method was as follows: reaction time 40 min, reaction temperature 80℃, hydrochloric acid concentration 1 mol / L, and material-to-liquid ratio 10:1.
[0012] Compared with existing technologies, the beneficial effects of this invention are as follows: Removing the activity of endogenous β-glucanase from the raw materials is a crucial step in the extraction of oat β-glucan. Typically, a high-temperature water bath (95°C) or a hot 80% ethanol solution is used to inactivate the enzyme. However, this invention employs a special high-power ultrasonic mode (300 W, 2-3 seconds per ultrasonic cycle, with 2-3 seconds of intermittent treatment) for a period of time. This fully utilizes the cavitation effect and internal thermal effect of ultrasound to rapidly inactivate the enzyme and promote the separation and rapid dissolution of β-glucan from other substances. As a result, the product yields a β-glucan content as high as 67.52%. Furthermore, activity analysis of β-glucan shows that it has an extremely strong scavenging ability against DPPH free radicals. Attached Figure Description
[0013] Figure 1 Infrared spectrum of oat β-glucan Figure 2 oat β-glucan molecules 1 H-NMR spectrum Figure 3 oat beta-glucan molecules 13 C-NMR spectrum Figure 4 XRD pattern of oat beta-glucan molecules Figure 5 Light scattering gel chromatogram of oat β-glucan Figure 6 The curve showing the relationship between the liquid-to-solid ratio and the total peak area of oligosaccharides. Figure 7 The curve showing the relationship between hydrochloric acid concentration and total oligosaccharide peak area. Figure 8 The curve of temperature versus total oligosaccharide peak area. Figure 9 Curve of time versus total oligosaccharide peak area Figure 10 Light scattering gel chromatogram of oat β-glucan degradation products Figure 11 Infrared spectrum of hydrolysis products Figure 12 X-ray diffraction pattern of hydrolysis products Figure 13 A graph showing the DPPH free radical scavenging ability of oat β-glucan acid degradation products. Detailed Implementation
[0014] The present invention will be further illustrated below with specific examples. It should be understood that these embodiments are for illustrative purposes only and do not limit the scope of the invention. After reading this invention, any modifications of the invention in various equivalent forms by those skilled in the art will fall within the scope defined by the appended claims.
[0015] The oat bran used in the examples was purchased from Zhangjiakou; the thermostable α-amylase was purchased from Innochem. Other materials and reagents used, unless otherwise specified, were commercially available. Example 1
[0016] Wash 5 kg of oat bran, dry it to a moisture content of 12.8%, and pulverize it through an 80-mesh sieve. Then, add water at a material-to-liquid ratio of 1:6 and slurry, allowing it to stand for 2 hours. Next, sonicate the suspension for 15 minutes in a 60℃ circulating water bath. The sonication mode was 300 W, with 2 seconds of sonication followed by a 2-second interval. After sonication, centrifuge the suspension twice (3000 rpm, 10 minutes each time), and combine the supernatants. Add 50 μl of heat-resistant α-amylase until the starch no longer turns blue. Then cool to room temperature, adjust the pH of the solution to 4.5, and incubate at 4℃ overnight (to allow for complete protein precipitation and improve the purity of the dextran). The suspension was centrifuged at 3000 r / min for 10 min, the supernatant was collected, the pH was adjusted to 7.0, and the volume was concentrated to 1 / 3 of the original volume. A 30% ethanol solution was added to the original volume, and the mixture was allowed to stand overnight at 4℃. The suspension was then centrifuged at 6000 rpm for 10 min, and the precipitate was collected (to remove free sugars, small proteins, and some nonpolar compounds). The precipitate was reconstituted with water and freeze-dried to obtain the β-glucan sample. Example 2
[0017] Wash 5 kg of oat bran, dry it to a moisture content of 13%, and pulverize it through a 60-mesh sieve. Then, add water at a material-to-liquid ratio of 1:8 and slurry, allowing it to stand for 1 hour. Sonicate the mixture for 10 minutes in a 60℃ circulating water bath at 300 W for 3 seconds followed by a 3-second interval. After sonication, centrifuge the suspension twice (3000 rpm, 10 minutes each time), and combine the supernatants. Add 50 μl of heat-resistant α-amylase until the starch does not turn blue. Cool to room temperature, adjust the pH to 4.5, and incubate overnight at 4℃ (to allow sufficient protein precipitation and improve dextran purity). Centrifuge the suspension at 3000 rpm for 15 minutes, collect the supernatant, adjust the pH to 7.0, concentrate to 1 / 3 of the original volume, add 30% ethanol solution to the original volume, and incubate overnight at 4℃. Centrifuge at 6000 rpm for 10 minutes and collect the precipitate (to remove free sugars, small proteins, and some non-polar compounds). The precipitate was reconstituted with water and freeze-dried to obtain the β-glucan sample. Example 3
[0018] Oat β-glucan was degraded using hydrochloric acid: reaction time 40 min, reaction temperature 80℃, hydrochloric acid concentration 1 mol / L, and material-to-liquid ratio 10:1.
[0019] Experimental Example 1 Purity determination of oat β-glucan The purity of the sample was determined using a two-enzyme method: 100 mg of the sample powder from Example 1 was weighed, and 0.2 mL of 50% ethanol and 4 mL of 20 mmol pH 6.5 sodium phosphate buffer were added. The mixture was vortexed and stirred every 60 seconds (3 times in total) in a boiling water bath. After incubation at 50°C for 5 min, 0.2 mL of 10 U lichenase was added, and incubation continued at 50°C for another 5 min. The mixture was then centrifuged at 1000 rpm for 10 min. 0.1 μL of the supernatant was placed in three test tubes. 0.1 mL of β-glucanase was added to tubes 1 and 2, and 0.1 mL of 50 mmol pH 4.0 sodium acetate buffer was added to tube 3. Distilled water was used as the blank control, and glucan was used as the reagent control. All three tubes were incubated in a 50°C water bath for 10 min, and 3 mL of GOPOD reagent was added. The mixture was incubated in a 50°C water bath for another 20 min, and the absorbance was measured at 510 nm.
[0020] The calculation is based on the following formula:
[0021] The purity of oat β-glucan in the product of Example 1 was 67.52%.
[0022] Experimental Example 2 Monosaccharide composition analysis of oat β-glucan (1) Complete hydrolysis of polysaccharides: 80 mg of the sample from Example 1 was added to 4 mL of 1 mol / L H2SO4 and hydrolyzed in an oil bath at 100 °C for 5 h. Then, it was neutralized with saturated Ba(OH)2, heated to boiling, and left to stand overnight to allow BaSO4 to precipitate and crystallize. The solution was filtered and the filtrate was used for later use.
[0023] (2) Paper chromatography: Weigh galactose, xylose, glucose and mannose standards respectively, prepare a 5.0 mg / mL aqueous solution with distilled water, spot 2.5 μL of the sample solution and spot 4 μL of the sample solution (dry immediately with an electric blower). After spotting, develop in a n-butanol:acetic acid:water = 4:1:5 (v / v / v) solvent system. After drying, spray with aniline-phthalic acid colorimetric reagent (1 mL of aniline and 1.66 g of phthalic acid dissolved in 100 mL of water-saturated n-butanol) and heat in an oven at 120 °C for 10 min for color development.
[0024] (3) High performance liquid chromatography: Galactose, xylose, glucose and mannose were used as standards. Ultrapure water was used as the mobile phase, the flow rate was 0.4 mL / min and the injection volume was 10 μL.
[0025] The experimental results are shown in Table 1:
[0026] The high-performance liquid chromatography (HPLC) separation retention times and paper chromatography Rf values of hydrolyzed samples of mannose, xylose, galactose, dextran, and oat β-glucan are shown in the table. This polysaccharide is a dextran composed of a single glucose unit.
[0027] Experimental Example 3 Fourier transform infrared spectroscopy Take 5 mg of oat β-glucan from Example 1, mix it with KBr, grind it, compress it into tablets, and then use BIO-RAD Win-IR at 500–4000 cm⁻¹. -1 We scanned within a certain range to analyze the bond structure of β-glucan.
[0028] Experimental results: from Figure 1 The following structural features of oat β-glucan can be observed: [The text abruptly ends here, likely due to an incomplete sentence or missing information.] -1 There is a broad peak at 3400 cm⁻¹, whose characteristic stretching vibrations belong to OH and CH, indicating that the product is a carbohydrate. -1 The distance is approximately 1643 cm, indicating the presence of significant intermolecular hydrogen bonds within the dextran molecule. -1 There is a weak absorption peak at 1000 cm⁻¹, which is attributed to the presence of a small amount of water of crystallization in oat β-glucan. -1The product exhibits a strong absorption peak, which is attributed to the stretching vibration of the ether bond (COC), and also at 1000 cm⁻¹. -1 The absorption peak at that location also confirms the presence of pyranose in oat β-glucan.
[0029] Test Example 4 Nuclear magnetic resonance 1 HNMR and 13 CNMR analysis Dissolve 1 mg of oat β-glucan sample from Example 1 in 1.5 mL L2O, centrifuge at 8000 rpm for 15 minutes, and transfer the supernatant to an NMR tube for further analysis. 1 H-NMR and 13 C-NMR analysis, 1 During H-NMR analysis, the external magnetic field frequency was 600MHz, the number of scans was 16, and the calibration was performed at 25℃ using solvent D2O (δ=4.78ppm). 13 During C-NMR analysis, the external magnetic field frequency was 150 MHz and the number of scans was 10240.
[0030] The experimental results are shown in Figure 2 1 In the H-NMR spectrum, the chemical shift signals of polysaccharides are mostly concentrated between δ3.5-5.5 ppm. Generally, the chemical shift of the proton at C-1 of α-pyranose is greater than 4.95 ppm, while the chemical shift of the proton at C-1 of β-pyranose is less than 4.95 ppm.
[0031] oat beta-glucan 13 C-NMR spectrum as shown Figure 3 As shown, two types of proton shift signals of the sugar ring are present at δ 3.98 ppm and 4.52 ppm, with chemical shifts both less than 4.95 ppm. Therefore, it can be inferred that the oat beta-glucan molecule contains β-type pyranose. Furthermore, the coupling constant of the terminal protons is 7.6, further proving that only β-glycosidic bonds exist in oat beta-glucan. According to literature reports, these two proton signals are caused by β-(1-3) and β-(1-4) bond connections, respectively, with a ratio of 1:2.4.
[0032]
[0033] Analysis of oat beta-glucan based on molecular structure diagram 13The C-NMR spectrum, with its characteristic signal peaks as shown in the figure, reveals no signal peak in the δ 90-100 ppm range, indicating the absence of α-type anomeric carbons in the sample. This also suggests the polysaccharide is free of starch contamination and that this end is a reducing end. In the low-field range above δ 100 ppm, two types of resonance signals are clearly observed: red shifts in C-1 caused by β-(1-3) and β-(1-4) bond residues, with chemical shifts of 102.52 ppm and 102.32 ppm, respectively. The resonance signal at δ 83.74 ppm indicates the presence of β-(1-3) glycosidic bonds in the sample. According to literature, the C-4 resonance signal caused by β-(1-3) residues in the β-glucan structure is at 67.92 ppm, indicating the absence of two consecutive β-1,3 bonded residues in the oat glucan structure. At δ less than 66 ppm, only one type of carbon signal is observed, indicating that this C-6 does not participate in bonding.
[0034] Experimental Example 5 Light scattering gel chromatography analysis Weigh a certain mass of oat β-glucan sample from Example 1, prepare a 10 mg / mL solution with distilled water, and filter it through a 0.22 μm filter membrane.
[0035] The absolute molecular weight, molecular weight distribution, and polydispersity index (Mw / Mn) of the samples were determined using a high-performance liquid chromatography-size exclusion chromatography (HPSEC) system coupled with a multi-angle laser scattering detector (MALLS) and a differential refractive index (RI). The wavelength λ of the He-Ne laser source in the MALLS was 632.8 nm. Shodx OHpakSB-804HQ and Shodx OHpakSB-805HQ columns were used, with 0.1 mol / L NaNO3 solution as the mobile phase. Peaks in the chromatograms were analyzed using Astra software.
[0036] Experimental results: (1) X-ray diffraction The XRD pattern of oat β-glucan is as follows: Figure 4 As shown, oat β-glucan exhibits sharp diffraction peaks characteristic of crystals, indicating that the oat polysaccharide sample can form crystalline regions. The crystallinity of oat β-glucan is 38.2%. The glucan molecule only shows one diffraction peak, which may be because although glucan does not easily form gels, it can form large aggregates, leading to the phenomenon of microgels and macromolecular entanglement in high molecular weight samples. In other words, oat β-glucan contains both crystalline and amorphous structures. Furthermore, the broad diffraction peaks of oat β-glucan indicate the presence of multiple crystal forms and lattice types.
[0037] (2) Molecular weight and distribution of water-soluble dextran The physicochemical properties of polysaccharides are often closely related to their molecular weight. The molecular weight of oat β-glucan can be determined by multi-angle laser light scattering gel chromatography. Using system software analysis, the weight-average molecular weight (Mw) of oat β-glucan was found to be 8.5 × 10⁻⁶. 5 g / mol yielded a polydispersity index (Mw / Mn) of 1.33. The polydispersity index can be used to represent the molecular weight distribution of polysaccharides; a smaller value indicates a more concentrated distribution of polysaccharide components and higher sample purity. In this invention, the polydispersity index of the water-soluble dextran obtained was 1.33, indicating that the molecular weight distribution of β-glucan is concentrated and uniform, with a purity of 99.4%. (See [reference needed]). Figure 5 .
[0038] Experimental Example 6 Example 1: Single-factor experiment on acid degradation of oat β-glucan (1) Effect of feed-to-liquid ratio on acidolysis products Five portions of oat β-glucan dry powder of a certain mass were weighed and added to 3M HCl at solid-liquid ratios of 2.5:1, 5:1, 7.5:1, 10:1, and 12.5:1 (m / v), respectively. The mixture was reacted at 80℃ for 40 min, cooled to room temperature, neutralized with 6M NaOH solution, and then passed through anion and cation exchange resins. After passing through a 0.22 μm water film, the mixture was loaded onto an amino column with 70% acetonitrile as the mobile phase and a flow rate of 1 mL / min. The content of oligosaccharides generated was expressed as the sum of the peak areas of the oligosaccharides.
[0039] Experimental results: As the material-to-liquid ratio increased, the yield of oligosaccharides gradually increased. At a material-to-liquid ratio of 7.5:1, the oligosaccharide peak area was the largest, and the total sugar content was the highest. As the sample concentration continued to increase, the oligosaccharide content began to decrease. (See...) Figure 6 .
[0040] (2) Effect of hydrochloric acid solution concentration on acidolysis products Five portions of oat β-glucan dry powder of a certain mass were weighed and added to hydrochloric acid solutions of 1, 3, 5, 7, and 9 mol / mL respectively at a certain solid-liquid ratio. The mixture was reacted at 80℃ for 40 min, cooled to room temperature, and then neutralized with 6M NaOH solution. The mixture was then passed through anion and cation exchange resins, through a 0.22 μm water film, and onto an amino column. The mobile phase was 70% acetonitrile, and the flow rate was 1 mL / min. The content of oligosaccharides generated was expressed as the sum of the peak areas of the oligosaccharides.
[0041] Depend on Figure 7 It can be seen that the oligosaccharide yield is highest when the hydrochloric acid concentration is 3 mol / L, and the yield decreases significantly when the hydrochloric acid concentration is lower or higher than this. +The cleavage of β-(1-4) and β-(1-3) glycosidic bonds is random and disordered. Acid hydrolysis for oligosaccharide preparation typically uses relatively low concentrations; for example, the hydrochloric acid concentration for preparing oligoglucomannan from konjac flour was 0.07 mol / L. In this study, the optimal hydrolysis condition was 3 mol / L, a relatively high concentration, indicating that oat β-glucan hydrolysis is not particularly difficult, hence the need for a higher hydrochloric acid concentration during hydrolysis.
[0042] (3) Effect of reaction temperature on acidolysis products Five portions of oat β-glucan dry powder of a certain mass were weighed and added to a certain hydrochloric acid solution at a certain solid-liquid ratio. The mixtures were reacted at 20, 40, 60, 80 and 100℃ for 40 min respectively. After cooling to room temperature, the mixtures were neutralized with 6M NaOH solution, then passed through anion and cation exchange resins, through a 0.22 μm water film, and onto an amino column. The mobile phase was 70% acetonitrile, and the flow rate was 1 mL / min. The content of oligosaccharides generated was expressed as the sum of the peak areas of the oligosaccharides.
[0043] From the above Figure 8 It can be seen that the hydrolysis temperature has a significant impact on the hydrolysis products of dextran. The oligosaccharide yield is highest when the acid hydrolysis temperature is 80℃, and the yield decreases significantly when the temperature is below or above 80℃.
[0044] (4) Effect of reaction time on acidolysis products Five portions of oat β-glucan dry powder of a certain mass were weighed and reacted at a certain solid-liquid ratio, a certain concentration of hydrochloric acid solution, and a certain temperature for 20, 40, 60, 80, and 100 min, respectively. After cooling to room temperature, the mixture was neutralized with 6M NaOH solution, then passed through anion and cation exchange resins, through a 0.22 μm water film, and then onto an amino column. The mobile phase was 70% acetonitrile, and the flow rate was 1 mL / min. The content of oligosaccharides generated was expressed as the sum of the peak areas of the oligosaccharides.
[0045] Depend on Figure 9 It can be seen that the oligosaccharide content first increases and then decreases. As the degradation time increases, the product gradually decreases. After 80 minutes of reaction, β-glucan is basically completely degraded.
[0046] (5) Orthogonal experiment To further verify the degree of hydrolysis of oat β-glucan, a four-factor, three-level orthogonal experiment was designed based on the above single-factor experiments to optimize the acid hydrolysis conditions of oat β-glucan. The orthogonal experiment followed the L9(3) model. 4 The design scheme is shown in the table below:
[0047] Table 3 shows that reaction time is the most important factor affecting oligosaccharide yield. Among the four factors, the order of influence on oligosaccharide yield is: hydrochloric acid concentration (B) > reaction temperature (C) > reaction time (D) > material-to-liquid ratio (A). The optimal conditions for the orthogonal experiment are A2B1C2D2, namely: reaction time 40 min, reaction temperature 80℃, hydrochloric acid concentration 1 mol / L, and material-to-liquid ratio 10:1.
[0048] Experimental Example 7 Structural characterization of oat β-glucan acid degradation products (1) Light scattering gel chromatography Weigh a certain mass of oat β-glucan sample, prepare a 10 mg / mL solution with distilled water, and filter it through a 0.22 μm filter membrane.
[0049] The absolute molecular weight, molecular weight distribution, and polydispersity index (Mw / Mn) of the samples were determined using a high-performance liquid chromatography-size exclusion chromatography (HPSEC) system coupled with a multi-angle laser scattering detector (MALLS) and a differential refractive index (RI). The wavelength λ of the He-Ne laser source in the MALLS was 632.8 nm. Shodx OHpakSB-804HQ and Shodx OHpakSB-805HQ columns were used, with 0.1 mol / L NaNO3 solution as the mobile phase. Peaks in the chromatograms were analyzed using Astra software.
[0050] The molecular weight of the hydrolysis products of oat β-glucan can be determined by multi-angle laser light scattering gel chromatography. Using system software analysis, the weight-average molecular weight (Mw) of oat β-glucan was found to be 3.44 × 10⁻⁶. 4 g / mol, see details Figure 10 .
[0051] (2) Fourier transform infrared spectrum Weigh 5 mg of oat β-glucan, mix it with KBr, grind it, compress it into tablets, and then use BIO-RAD Win-IR at 500–4000 cm⁻¹. -1 We scanned within a certain range to analyze the bond structure of β-glucan.
[0052] Infrared spectra of oat β-glucan acid degradation products are shown below. Figure 11As shown, the oat β-glucan acid degradation product exhibits a strong absorption peak at 1020 cm⁻¹, which is due to the stretching vibration of the ether bond (COC). The absorption peaks around 1500-1600 cm⁻¹ are due to the stretching vibrations of C=O and -CHO. Simultaneously, the absorption peak at 1000 cm⁻¹ belongs to the characteristic vibrations of the β-pyran ring, which is a characteristic absorption peak of β-glucan. These results indicate that the oat β-glucan acid degradation product has the same basic structure as oat β-glucan, and acid degradation has not destroyed the basic structure of oat β-glucan.
[0053] (3) X-ray diffraction Measurement conditions: copper target, tube current 30mA, tube voltage 30kV, scan speed 3° / min, scan step size 0.04°. Scanning mode: continuous, repeated once, scan range: 4-50°. The XRD patterns of oat beta-glucan degradation products are shown below. Figure 12 As shown in the figure, the spectral density indicates that the degradation products are within a 2θ range of 5°–50°. This suggests the presence of crystals in the degradation product sample.
[0054] (4) DPPH free radical elimination experiment Add 2.0 mL of DPPH (0.1 mmol·L⁻¹) -1 10% ethanol solution was incubated together with test samples (2.0 mL) of different concentrations. The mixture was thoroughly shaken and incubated in the dark for 30 minutes. The absorbance A1 of the solution was then measured at 517 nm. The absorbance A0 was measured using deionized water instead of the sample solution, and A2 was measured using anhydrous ethanol instead of DPPH.
[0055] The free radical scavenging ability of oat β-glucan acid degradation products, such as Figure 13 As shown, high concentrations of the degradation products exhibit strong scavenging ability against DPPH free radicals, with a 50% inhibition (IC50) of 5.83 mg / mL.
[0056] (5) Fat binding capacity The sample (0.2 g) was dissolved in 10 mL of soybean oil and vortexed continuously for 15 min, then kept at room temperature for 1 h. It was then centrifuged at 1600 rpm for 20 min. The fat-binding capacity was expressed as the ratio between the wet and dry weights of the sediment sample, as shown in Table 4.
[0057] (6) Swelling capacity Add the sample (0.3 g) to distilled water (10 mL), stir at 70 °C for 10 min, then place in boiling water for 10 min, rinse the tube with tap water for 5 min, cool, and centrifuge at 2000 r·min⁻¹ for 5 min. Calculate the expansion force using the ratio between the wet weight and the dry sample weight. See Table 4.
[0058]
[0059] It is evident that the degradation products of oat β-glucan have enhanced fat-binding capacity. In the digestive tract, the increased binding volume of carbohydrates and fats makes them less easily absorbed by the body, thus leading to the excretion of fat and achieving the effect of lowering blood lipids.
Claims
1. A method for extracting oat β-glucan, characterized in that... The method includes the following steps: (1) Grind the oat bran through a 60-80 mesh sieve, then add water at a material-to-liquid ratio of 1:6-8 to make a slurry, and let it stand for 1-2 hours; then treat it with ultrasound for 10-15 minutes under a 60℃ circulating water bath. The ultrasound treatment mode is: power 300W, every 2-3 seconds of ultrasound, with a 2-3 second interval. (2) After sonication, the suspension was centrifuged twice, the supernatants were combined, and heat-resistant α-amylase was added until the starch did not turn blue. Then the suspension was cooled to room temperature, the pH of the solution was adjusted to 4.5, and the suspension was left to stand overnight at 4°C. The resulting suspension was centrifuged at 3000 r / min for 10-15 min, the supernatant was collected, the pH was adjusted to 7.0, the suspension was concentrated to 1 / 3 of the original volume, 30% ethanol solution was added, and the suspension was left to stand overnight at 4°C. The suspension was then centrifuged at 6000 rpm for 10-15 min, the precipitate was collected, the precipitate was reconstituted with water, and the precipitate was freeze-dried to obtain oat β-glucan.
2. The method for extracting oat β-glucan according to claim 1, characterized in that... The oat bran mentioned in step (1) is washed, dried to a moisture content of 12-13%, and then crushed.
3. The method for extracting oat β-glucan according to claim 2, characterized in that... The oat bran mentioned in step (1) is washed, dried to a moisture content of 12.8%, and then crushed.
4. The method for extracting oat β-glucan according to claim 1, characterized in that... Step (1) involves adding water at a ratio of 1:6 to make a pulp.
5. The method for extracting oat β-glucan according to claim 1, characterized in that... The suspension centrifuged twice in step (2) specifically means that the centrifugation speed is 3000 r / min each time and the centrifugation time is 10-15 min each time.
6. A method for acid degradation of oat β-glucan obtained by the method of claim 1, characterized in that: The reaction time was 40 min, the reaction temperature was 80℃, the hydrochloric acid concentration was 1 mol / L, and the material-to-liquid ratio was 10:1.