Grain bran polysaccharide extraction method
Through technical means such as supercritical carbon dioxide extraction method and enzymatic treatment, the use of organic solvents has been successfully avoided, the problems of environmental pollution and high cost in traditional extraction methods have been solved, and the extraction and large-scale production of high-purity cereal bran polysaccharides have been achieved.
Patent Information
- Application Number
- CN202510616075.0
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-05-14
- Publication Date
- 2025-06-27
AI Technical Summary
The traditional method of extracting cereal bran arabinoxicans from the Arabic-xylcans uses a large amount of organic solvents, which leads to environmental pollution and high production costs, and makes it difficult to achieve high purity extraction.
Supercritical carbon dioxide extraction method was used to deoilate, combined with enzymatic lysis and alkaline deconstructive shearing treatment, followed by adjustment of pH value for membrane filtration and spray drying, avoiding the use of organic solvents.
It realizes the extraction of high-purity cereal bran polysaccharides, reduces production costs and environmental pollution, and is suitable for large-scale production.
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Abstract
Description
Technical Field
[0001] The present invention relates to the technical field of polysaccharide extraction, and particularly relates to a method for extracting polysaccharides from cereal bran. Background Art
[0002] As a by-product generated during the deep processing of cereals, cereal bran contains a large amount of cellulose and hemicellulose and is a good source of natural dietary fiber. One of the main components in cereal bran is hemicellulose B, namely arabinoxylan, also called pentosan, which is an important component of the plant cell wall. According to solubility, it is usually divided into two categories: water-soluble arabinoxylan and water-insoluble arabinoxylan, and the main component in cereal bran is water-insoluble arabinoxylan. It has lactone bonds covalently linked at ferulic acid sites with other components such as lignin and cellulose, so it cannot be directly dissolved out when extracting cereal arabinoxylan. For the extraction of cereal bran arabinoxylan, it is mainly the alkali method. Under the conditions of strong alkali and high temperature, hydroxyl groups break the covalent ester bonds, thereby releasing arabinoxylan. In the traditional alkali extraction process, n-hexane is generally used for deoiling and ethanol is used for purification. The usage amount of organic solvents is too large, posing a certain threat to the environment and being unfavorable for large-scale production. Summary of the Invention
[0003] The purpose of the present invention is to provide a method for extracting polysaccharides from cereal bran. The method of the present invention does not use organic solvents, is environmentally friendly, and the polysaccharides extracted from cereal bran have a relatively high purity and are suitable for large-scale production.
[0004] In order to achieve the above-mentioned invention purpose, the present invention provides the following technical solutions: The present invention provides a method for extracting polysaccharides from cereal bran, without using organic solvents, comprising the following steps: Performing a deoiling treatment on cereal bran by using supercritical carbon dioxide extraction to obtain deoiled cereal bran; Performing a de-starching treatment on the deoiled cereal bran to obtain de-starched material; Performing a deconstruction treatment and a shearing treatment on the de-starched material in sequence under alkaline conditions to obtain an alkali extract solution; Adjusting the pH value of the alkali extract solution to an acidic condition, collecting the supernatant after centrifugation, and then performing a membrane filtration treatment and a spray drying in sequence to obtain the polysaccharides from cereal bran.
[0005] Preferably, the conditions of the deoiling treatment include: the temperature is 45 - 60 °C, the pressure is 25 - 35 MPa, and the time is 1 - 3 h.
[0006] Preferably, the starch removal treatment includes: mixing the defatted cereal bran with water for gelatinization treatment, mixing the obtained gelatinized treatment liquid with amylase, adjusting the pH value of the obtained mixed liquid to 6.6 - 6.8, and performing enzymatic hydrolysis treatment to obtain the starch-removed material.
[0007] Preferably, the mass ratio of the defatted cereal bran to the water used for gelatinization treatment is 1:5 - 9; the temperature of the gelatinization treatment is 80 - 90°C, and the time is 0.5 - 1.5 h; the amylase is thermostable α-amylase; the temperature of the enzymatic hydrolysis treatment is 80 - 90°C, and the time is 20 - 30 min.
[0008] Preferably, the alkaline condition is pH ≥ 11.5; the reagent used to adjust the alkaline condition is solid sodium hydroxide.
[0009] Preferably, taking one deconstruction treatment and one shearing treatment as one cycle, the number of cycles is 2 - 3 times; the conditions for each deconstruction treatment include: temperature 80 - 90°C, time 0.5 - 1.5 h; the conditions for each shearing treatment include: rotation speed 10000 - 20000 rpm, time 50 - 70 min.
[0010] Preferably, the acidic condition is pH = 3 - 5; the reagent used to adjust the acidic condition is concentrated hydrochloric acid, and the concentration of the concentrated hydrochloric acid is 11.6 - 12 mol / L.
[0011] Preferably, the filter membrane used for the membrane filtration treatment is a ceramic membrane, and the pore size of the ceramic membrane is 0.05 μm; the pressure of the membrane filtration treatment is 2 - 4 bar; the conductivity of the concentrated liquid obtained after the membrane filtration treatment is ≤ 0.6 mS / cm.
[0012] Preferably, the conditions for spray drying include: inlet air temperature 165 - 175°C, outlet air temperature 85 - 95°C.
[0013] Preferably, the purity of the cereal bran polysaccharide is 65 - 80 wt%.
[0014] The present invention provides a method for extracting cereal bran polysaccharide without using organic solvents, which comprises the following steps: performing defatting treatment on cereal bran by supercritical carbon dioxide extraction method to obtain defatted cereal bran; performing de-starching treatment on the defatted cereal bran to obtain de-starched material; performing deconstruction treatment and shearing treatment on the de-starched material in alkaline condition in sequence to obtain an alkaline extract solution; adjusting the pH value of the alkaline extract solution to acidic condition, collecting the supernatant after centrifugation, and then performing membrane filtration treatment and spray drying in sequence to obtain the cereal bran polysaccharide. The present invention uses supercritical carbon dioxide extraction technology to replace organic solvents such as n-hexane to remove oil, and uses membrane filtration treatment and spray drying to replace ethanol washing, avoiding the use of organic solvents in the whole extraction process. It can not only obtain high-purity products, but also solve the problems of high cost brought by organic solvents in polysaccharide extraction and high risks and hazards brought by the use of organic solvents in actual industrial production. In addition, the method of the present invention has high efficiency, continuity, environmental protection and easy regulation, and has broad application prospects in industrial extraction of cereal bran polysaccharide. The results of examples show that high-purity cereal bran polysaccharide can be obtained by using the method of the present invention under pilot scale conditions. Detailed implementation mode
[0015] The present invention provides a method for extracting cereal bran polysaccharide without using organic solvents, which comprises the following steps: Performing defatting treatment on cereal bran by supercritical carbon dioxide extraction method to obtain defatted cereal bran; Performing de-starching treatment on the defatted cereal bran to obtain de-starched material; Performing deconstruction treatment and shearing treatment on the de-starched material in alkaline condition in sequence to obtain an alkaline extract solution; Adjusting the pH value of the alkaline extract solution to acidic condition, collecting the supernatant after centrifugation, and then performing membrane filtration treatment and spray drying in sequence to obtain the cereal bran polysaccharide.
[0016] In the present invention, unless otherwise specified, the raw materials used are commercially available products well-known to those skilled in the art. The water used in the present invention is preferably pure water.
[0017] The present invention uses the supercritical carbon dioxide extraction method to de-oil cereal bran, obtaining de-oiled cereal bran. As an embodiment of the present invention, the cereal bran may include one or several of corn bran, sorghum bran, and wheat bran, specifically it may be corn bran, sorghum bran, or wheat bran. As an embodiment of the present invention, it is preferred to crush and screen the cereal bran before the de-oiling treatment. The mesh number of the sieve used for screening is 20 meshes, and the undersize is collected for the de-oiling treatment. As an embodiment of the present invention, specifically, the cereal bran is placed in the extraction kettle of a supercritical carbon dioxide extractor for de-oiling treatment; the conditions for the de-oiling treatment include: the temperature can be 45-60°C, further it can be 55-60°C; the pressure can be 25-35 MPa, specifically it can be 30 MPa; the time is 1-3 h, further it can be 2-3 h. As an embodiment of the present invention, no post-treatment is required after the de-oiling treatment, and the de-oiled cereal bran is directly obtained. The present invention uses the supercritical carbon dioxide extraction method to de-oil cereal bran, which can effectively remove the oil in the bran, and is beneficial to improving the storage stability (preventing the generation of rancid smell due to oil oxidation during storage).
[0018] After obtaining the de-oiled cereal bran, the present invention conducts a de-starching treatment on the de-oiled cereal bran to obtain a de-starched material. As an embodiment of the present invention, the de-starching treatment may include: mixing the de-oiled cereal bran with water for gelatinization treatment, mixing the obtained gelatinized treatment liquid with amylase, adjusting the pH value of the obtained mixed liquid to 6.6-6.8, and performing enzymatic hydrolysis treatment to obtain the de-starched material. As an embodiment of the present invention, the mass ratio of the de-oiled cereal bran to the water used for gelatinization treatment can be 1:5-9, further it can be 1:6-8, specifically it can be 1:7; the temperature of the gelatinization treatment can be 80-90°C, further it can be 85-90°C; the time can be 0.5-1.5 h, specifically it can be 1 h. The present invention can make the starch fully expand through gelatinization treatment, which is beneficial to subsequent starch removal and improves the purity of the final product.
[0019] The present invention adjusts the pH value of the mixed liquid to 6.6-6.8, which can control the pH value environment in the optimal environment of amylase, and is beneficial to amylase to fully remove starch. As an embodiment of the present invention, the reagent used to adjust the mixed liquid can be NaOH solution, and the concentration of the NaOH solution can be 19.06 mol / L.
[0020] As an embodiment of the present invention, the amylase can be thermostable α-amylase; based on every 1 kg of de-oiled cereal bran, the activity of the thermostable α-amylase can be 6.5×10 5 ~7×10 5U. As an embodiment of the present invention, the temperature of the enzymatic hydrolysis treatment can be 80 to 90 °C, specifically 85 to 90 °C; the time can be 20 to 30 min, further 25 to 30 min; the enzymatic hydrolysis treatment can be carried out under stirring conditions. As an embodiment of the present invention, after the enzymatic hydrolysis treatment, it is preferably to inactivate the enzyme in the obtained system through a tubular enzyme inactivator, and then transport the obtained enzymatically hydrolyzed feed liquid to a disc centrifuge for centrifugation, and collect the solid material as the de-starch material; the number of centrifugations can be 2 to 3 times; the rotational speed of each centrifugation can be 10,000 to 20,000 rpm, specifically 16,000 rpm; the time of each centrifugation can be 20 to 50 min, specifically 30 min. In the examples of the present invention, the de-starch treatment is carried out under the above conditions, which can fully remove starch and is beneficial to avoiding the influence of starch and small molecular sugars decomposed from starch on the purity of the final product.
[0021] After obtaining the de-starch material, the present invention subjects the de-starch material to a deconstruction treatment and a shearing treatment in sequence under alkaline conditions to obtain an alkali extract solution. As an embodiment of the present invention, specifically, the de-starch material is mixed with water, the pH value of the system is adjusted to alkaline conditions, and the deconstruction treatment and the shearing treatment are carried out in sequence. As an embodiment of the present invention, the mass ratio of the de-starch material to water can be 1:5 to 10, specifically 1:8; the alkaline conditions can be pH ≥ 11.5, specifically 11.5 to 12.5; the reagent used to adjust the alkaline conditions can be solid sodium hydroxide. As an embodiment of the present invention, taking one deconstruction treatment and one shearing treatment as one cycle, the number of cycles can be 2 to 3 times. As an embodiment of the present invention, the conditions for each deconstruction treatment include: the temperature can be 80 to 90 °C, specifically 85 °C; the time can be 0.5 to 1.5 h, specifically 1 h. As an embodiment of the present invention, the conditions for each shearing treatment include: the rotation speed can be 10,000 to 20,000 rpm, specifically 16,000 rpm; the time can be 50 to 70 min, specifically 60 min. After completing one cycle, the present invention preferably centrifuges the obtained system, separately collects the supernatant and the precipitate, subjects the precipitate to the next cycle, and finally combines the supernatants obtained from each centrifugation as the alkali extract solution. As an embodiment of the present invention, the centrifugation can be specifically carried out in a disc centrifuge; the number of centrifugations can be 2 to 3 times, the rotation speed of each centrifugation can be independently 10,000 to 20,000 rpm, specifically 16,000 rpm; the time of each centrifugation can be independently 20 to 60 min, specifically 40 min. In the examples of the present invention, under the above conditions, the deconstruction treatment and the shearing treatment can fully dissociate the hemicellulose from the cereal bran, thereby effectively separating various components in the bran, and the extraction process is simple and stable and can improve the extraction rate of cereal bran polysaccharides.
[0022] After obtaining the alkaline extract solution, the present invention adjusts the pH value of the alkaline extract solution to an acidic condition, collects the supernatant after centrifugation, and then sequentially performs membrane filtration treatment and spray drying to obtain the cereal bran polysaccharide. As an embodiment of the present invention, the acidic condition can be a pH value of 3-5, and further can be 4-4.5; the reagent used to adjust the acidic condition is concentrated hydrochloric acid, and the concentration of the concentrated hydrochloric acid can be 11.6-12 mol / L. As an embodiment of the present invention, after adjusting the pH value of the alkaline extract solution to an acidic condition, solids precipitate in the system. After centrifugation, the supernatant (i.e., the solution containing cereal bran polysaccharide) is collected, and then sequentially performs membrane filtration treatment and spray drying to obtain the cereal bran polysaccharide. As an embodiment of the present invention, the centrifugation can be specifically carried out in a disc centrifuge; the rotation speed of the centrifugation can be 10,000-20,000 rpm, specifically can be 16,000 rpm; the centrifugation time can be 20-60 min, specifically can be 40 min. As an embodiment of the present invention, the filtration membrane used for the membrane filtration treatment can be a ceramic membrane, and the pore size of the ceramic membrane can be 0.05 μm; the pressure of the membrane filtration treatment can be 2-4 bar, specifically can be 3 bar; the conductivity of the concentrated solution obtained after the membrane filtration treatment can be ≤0.6 mS / cm. The present invention removes impurities such as ash and small molecule sugars through membrane filtration treatment. As an embodiment of the present invention, the conditions of the spray drying can include: the inlet air temperature can be 165-175 °C, specifically can be 160 °C; the outlet air temperature can be 85-95 °C, specifically can be 90 °C. In the examples of the present invention, the spray drying treatment can be specifically carried out in a spray dryer.
[0023] The method of the present invention does not use a large amount of organic solvents, is environmentally friendly, and the cereal bran polysaccharide obtained by extraction has a relatively high purity and is suitable for large-scale production. The cereal bran polysaccharide of the present invention is specifically cereal bran arabinoxylan. As shown by the results of the examples, in the case of pilot scale, the purity of the cereal bran polysaccharide obtained by using the method of the present invention is 65-85 wt% (dry basis), specifically can be 72 wt%, 73 wt% or 76 wt%.
[0024] Next, the technical solutions in the present invention will be clearly and completely described in conjunction with the examples in the present invention. Obviously, the described examples are only a part of the examples of the present invention, rather than all the examples. Based on the examples in the present invention, all other examples obtained by those of ordinary skill in the art without making creative efforts belong to the protection scope of the present invention.
[0025] Example 1 Pilot scale Crush cereal bran (specifically corn bran) with a crusher and pass it through a 20-mesh sieve. Collect the material under the sieve to obtain cereal bran powder; add the cereal bran powder to the extraction kettle of a supercritical carbon dioxide extractor and perform defatting treatment for 3 h at a temperature of 60 °C and a pressure of 30 MPa to obtain defatted cereal bran; Mix the defatted cereal bran and water at a mass ratio of 1:7 and add them to an enzymatic hydrolysis tank. Perform gelatinization treatment at 90 °C for 1 h. Then add thermotolerant α-amylase to the enzymatic hydrolysis tank (add 6.5×10 5 U of thermotolerant α-amylase activity per 1 kg of defatted cereal bran), and adjust the pH value of the system to 6.6 with a NaOH solution with a concentration of 19.06 mol / L. Perform enzymatic hydrolysis treatment at a temperature of 87 °C for 30 min (use iodine solution to detect that there is no starch in the system, indicating complete enzymatic hydrolysis); after the enzymatic hydrolysis treatment is completed, inactivate the enzyme through a tubular enzyme inactivator, and then transport the obtained enzymatically hydrolyzed feed liquid to a disc centrifuge. Centrifuge three times at a rotation speed of 16,000 rpm, with each centrifugation time of 30 min, and collect the solid material as de-starch material; Mix the de-starch material and water at a mass ratio of 1:8 and add them to a material tank. Heat to 85 °C under stirring conditions. During the heating process, adjust the pH value of the system to 11.5 with solid NaOH, keep warm for 1 h for deconstruction treatment. Perform shearing treatment on the obtained deconstructed feed liquid at a rotation speed of 16,000 rpm for 1 h. Then transport the obtained sheared feed liquid to a disc centrifuge. Centrifuge three times at a rotation speed of 16,000 rpm, with each centrifugation time of 40 min, and collect the supernatant as an alkali extract solution; Adjust the pH value of the alkali extract solution to 4 with hydrochloric acid (concentration of 12 mol / L), transport the obtained feed liquid to a disc centrifuge, and centrifuge for 40 min at a rotation speed of 16,000 rpm. Collect the supernatant as a solution containing cereal bran arabinoxylan; perform membrane filtration treatment on the solution containing cereal bran arabinoxylan at a pressure of 3 bar and a ceramic membrane pore size of 0.05 μm to obtain a concentrate with a conductivity ≤0.6 mS / cm; transfer the concentrate to a spray dryer for spray drying treatment (inlet air temperature is 170 °C, outlet air temperature is 90 °C) to obtain cereal bran arabinoxylan (specifically corn bran arabinoxylan).
[0026] Example 2 Operate according to the method of Example 1, with the difference that corn bran is replaced by wheat bran, and finally obtain wheat bran arabinoxylan.
[0027] Example 3 Operate according to the method of Example 1, except that corn bran is replaced with sorghum bran, and finally sorghum bran arabinoxylan is obtained.
[0028] Comparative Example 1 Pilot scale Crush cereal bran (specifically corn bran) with a crusher and pass through a 40-mesh sieve, and collect the material under the sieve to obtain cereal bran powder; mix the cereal bran powder with n-hexane at a mass ratio of 1:7, and perform defatting treatment at room temperature for 1 h. Then, filter the obtained system to remove the organic solvent to obtain defatted cereal bran; Mix the defatted cereal bran with water at a mass ratio of 1:7, heat to boiling for gelatinization treatment for 1 h, then cool to 85 °C, add thermostable α-amylase to the obtained gelatinized system (the activity of thermostable α-amylase added per 100 g of steam-exploded cereal bran is 6.5×10 4 U), and adjust the pH value of the system to 6.6 with a NaOH solution with a concentration of 19.06 mol / L, and keep warm under stirring for enzymatic hydrolysis treatment for 30 min (using iodine solution to detect that there is no starch in the system indicates that enzymatic hydrolysis is complete); after the enzymatic hydrolysis treatment is completed, heat to boiling to inactivate the enzyme, and then wash the obtained system with water by centrifugation three times to obtain de-starch material; Mix the de-starch material with water at a mass ratio of 1:8, heat to 85 °C under stirring, and adjust the pH value of the system to 11.5 with a NaOH solution with a concentration of 50 wt% during the heating process, keep warm for deconstruction treatment for 1 h, shear the obtained deconstruction treatment liquid at a rotation speed of 16,000 rpm for 1 h, then centrifuge the obtained sheared treatment liquid, and collect the supernatant and precipitate respectively. Repeat the deconstruction treatment, shearing treatment and centrifugation once for the precipitate according to the above steps, and combine the supernatants to obtain an alkali extract solution; Adjust the pH value of the alkali extract solution to 4 with hydrochloric acid (concentration of 12 mol / L), centrifuge, and collect the supernatant to obtain a solution containing cereal bran arabinoxylan; Mix the solution containing cereal bran arabinoxylan with absolute ethanol at a volume ratio of 1:2, place it in a refrigerator at 4 °C for 12 h, then remove the supernatant in the obtained system without disturbing the precipitate below, wash the precipitate three times with absolute ethanol, and place the washed precipitate in an oven to dry to obtain cereal bran arabinoxylan (specifically corn bran arabinoxylan).
[0029] Comparative Example 2 Operate according to the method of Comparative Example 1, except that corn bran is replaced with wheat bran, and finally wheat bran arabinoxylan is obtained.
[0030] Comparative Example 3 Operate according to the method of Comparative Example 1, except that corn bran is replaced with sorghum bran, and finally sorghum bran arabinoxylan is obtained.
[0031] Test Example 1 The quality of raw materials and products in different treatment steps and the purity of the finally obtained cereal bran arabinoxylan in each example and comparative example are shown in Table 1. The results show that under the conditions of pilot scale, the purity of the cereal bran arabinoxylan prepared by the method of the present invention is relatively high, which is basically equivalent to that of the cereal bran arabinoxylan prepared by the method of deoiling treatment with organic solvents. However, in actual situations, if pilot scale or even larger scale tests and industrial production are carried out, the cost of using a large amount of organic solvents is relatively high, and it will pose a certain threat to the environment. Therefore, the method of the present invention is more suitable for large-scale production.
[0032] Table 1 Quality of raw materials and products in different treatment steps and purity of cereal bran arabinoxylan
[0033] The above are only the preferred embodiments of the present invention. It should be noted that for those of ordinary skill in the art, without departing from the principle of the present invention, several improvements and refinements can be made, and these improvements and refinements should also be regarded as the protection scope of the present invention.
Claims
1. A method for extracting cereal bran polysaccharides, characterized in that: No organic solvents are used and the following steps are included: The cereal bran is deoiled by supercritical carbon dioxide extraction to obtain deoiled cereal bran; The de-oiled cereal bran is subjected to a de-starch treatment to obtain a de-starch material; The destarch material is subjected to deconstruction treatment and shearing treatment in sequence under alkaline conditions to obtain an alkaline extract solution; The pH value of the alkaline extract solution is adjusted to an acidic condition, and the supernatant is collected after centrifugation, and then membrane filtration and spray drying are performed in sequence to obtain the cereal bran polysaccharide.
2. The extraction method according to claim 1, characterized in that The deoiling treatment conditions include: temperature of 45-60° C., pressure of 25-35 MPa, and time of 1-3 h.
3. The extraction method according to claim 1 or 2, characterized in that The destarch treatment comprises: mixing the de-oiled cereal bran with water for gelatinization treatment, mixing the obtained gelatinization treatment liquid with amylase, adjusting the pH value of the obtained mixed liquid to 6.6-6.8, performing enzymatic hydrolysis treatment, and obtaining the destarch material.
4. The extraction method according to claim 3, characterized in that The mass ratio of the de-oiled cereal bran to the water used for gelatinization treatment is 1:5-9; the temperature of the gelatinization treatment is 80-90°C, and the time is 0.5-1.5h; the amylase is a high-temperature resistant α-amylase; the temperature of the enzymatic hydrolysis treatment is 80-90°C, and the time is 20-30min.
5. The extraction method according to claim 1, characterized in that The alkaline condition is a pH value ≥ 11.5; the reagent used to adjust the alkaline condition is solid sodium hydroxide.
6. The extraction method according to claim 1 or 5, characterized in that One deconstruction treatment and one shearing treatment is counted as one cycle, and the number of cycles is 2 to 3 times; The conditions of each deconstruction treatment include: temperature of 80-90° C. and time of 0.5-1.5 h; the conditions of each shear treatment include: rotation speed of 10000-20000 rpm and time of 50-70 min.
7. The extraction method according to claim 1, characterized in that The acidic condition is pH=3-5; the reagent used to adjust the acidic condition is concentrated hydrochloric acid, and the concentration of the concentrated hydrochloric acid is 11.6-12 mol / L.
8. The extraction method according to claim 1 or 7, characterized in that The filtration membrane used in the membrane filtration treatment is a ceramic membrane, and the pore size of the ceramic membrane is 0.05 μm; the pressure of the membrane filtration treatment is 2-4 bar; and the conductivity of the concentrated liquid obtained after the membrane filtration treatment is ≤0.6 mS / cm.
9. The extraction method according to claim 1, characterized in that The spray drying conditions include: an air inlet temperature of 165-175°C and an air outlet temperature of 85-95°C.
10. The extraction method according to claim 1, characterized in that The purity of the cereal bran polysaccharide is 65-80wt%.