Method for preparing cellobiose and comprehensively utilizing by-products of cellobiose

Abstract

The invention discloses a method for preparing cellobiose and comprehensively utilizing a by-product of cellobiose. The method is characterized by specifically comprising the following steps: (1) dilution, (2) enzymolysis, (3) flocculation and carbon explosion, (4) decoloration, (5) continuous ion exchange, (6) evaporation and concentration, (7) simulated moving bed chromatographic separation, (8) concentration, (9) finished product preparation and (10) raffinate utilization. The method effectively solves the problems of low preparation purity and high production cost of cellobiose.

Description

Technical Field

[0001] The invention belongs to the technical field of functional sugar production, and specifically relates to a method for preparing cellobiose and comprehensive utilization of its by-products. Background Art

[0002] Cellobiose, also known as cellobiose alcohol, has a chemical formula of C 12 H 22 O 11 , a white crystalline powder, is a product of cellulose hydrolysis and a disaccharide formed by two glucose molecules connected by a β-1,4-glycosidic bond. In nature, cellobiose is a part of cellulose and is widely present in plant cell walls. As a natural sweetener, cellobiose has been widely used in the food industry. Due to its low calories, low glycemic index and good taste, cellobiose is gradually becoming the preferred sweetener for healthy foods. In addition, cellobiose also has a variety of physiological functions such as improving the balance of intestinal microecology and promoting the growth of probiotics. It has significant effects on preventing constipation, lowering the glycemic index and improving human immunity.

[0003] In addition to the food industry, cellobiose also shows broad application prospects in the fields of medicine and cosmetics. In the field of medicine, cellobiose can be used as a drug carrier to improve the stability and bioavailability of drugs. In the field of cosmetics, cellobiose has moisturizing and anti-aging effects, and is an important ingredient in many high-end skin care products.

[0004] D-xylose is a pentose obtained by hydrolysis of hemicellulose-rich plants such as sawdust, straw, and corn cobs. Its chemical formula is C 5 H 10 O 5 . Colorless to white crystals or white crystalline powder, with a slightly special smell and refreshing sweetness. Melting point 114℃, dextrorotatory and mutarotatory, easily soluble in hot ethanol; sweetness is 72% of sucrose, close to the sweetness of glucose, and the flavor is similar to glucose. It can improve the flavor and taste of sweets and inhibit odor. Natural D-xylose exists in plants in the form of polysaccharides, and is more abundant in waste parts of agricultural products such as corn cobs, cottonseed hulls, bagasse, rice husks, and other straws, seed husks, etc.

[0005] As an emerging functional food ingredient, D-xylose is widely used in various functional foods due to its excellent processing characteristics and multiple physiological regulatory functions. Its physiological regulatory functions mainly include: regulating intestinal flora and promoting the proliferation of beneficial intestinal bacteria such as bifidobacteria. In the process of metabolism, beneficial intestinal flora will produce vitamin B 1 , Vitamin B 2 , Vitamin B 6 , Vitamin B 12, niacin and folic acid, etc. These nutrients can be absorbed and utilized by the human body, achieving the health care function of supplementing multiple nutrients for the human body; lowering blood pressure, serum cholesterol and blood sugar; D-xylose cannot be utilized by oral bacteria, nor can it be decomposed by oral enzymes. Therefore, it will not cause tooth decay and is conducive to maintaining oral hygiene.

[0006] The traditional preparation method of xylose is to obtain xylose crystals by pretreatment, hydrolysis, neutralization and decolorization, ion exchange, concentration and crystallization of raw materials. However, the xylose mother liquor after centrifugation generally has problems such as heavy pigments and many impurities. It is generally used as waste in the production process, which leads to a certain degree of resource waste. Cellobiose can be synthesized by a variety of methods, including acid-catalyzed glucose dehydration, cellulase hydrolysis and base-catalyzed condensation of two glucose molecules. Acid-catalyzed glucose dehydration is the most commonly used method for synthesizing cellobiose. This method involves the reaction of glucose and acid (such as hydrochloric acid) under high temperature and high pressure. The resulting product is a mixture of cellobiose and other glucose-based compounds. Generally, the purity of cellobiose is low and the production cost is high. Summary of the invention

[0007] In order to solve the defects of the prior art in the background technology and further improve the comprehensive utilization efficiency of resources. The present invention creatively uses xylose mother liquor as raw material, adopts dilution enzymatic hydrolysis, flocculation carbon explosion, decolorization precision filtration, continuous ion exchange, simulated moving bed chromatography separation and other processes, and then performs crystallization, centrifugation and drying to prepare cellobiose and xylose respectively. Continuous, automatic and clean production is achieved.

[0008] A method for preparing cellobiose and comprehensive utilization of its byproducts specifically comprises the following steps: (1) Dilution: dilute the xylose mother liquor with sweet water to meet the purification process requirements such as carbon explosion, filtration, and ion exchange; (2) Enzymatic hydrolysis: Xylanase is added to the diluted mother liquor to decompose the polysaccharides in the mother liquor into xylose.

[0009] (3) Flocculation carbon explosion: After enzymatic hydrolysis, the mother liquor is heated to a certain temperature to inactivate the xylanase, a flocculant is added for pre-sedimentation, and then calcium hydroxide is used for alkalization. Carbon dioxide gas is then introduced for bubbling and micro-explosion. While calcium carbonate is produced, impurities such as protein, colloid, and lignin in the xylose mother liquor are complexed and precipitated together with calcium carbonate, and precipitated.

[0010] (4) Decolorization: Add powdered activated carbon to the material after carbon explosion and stir to decolorize it. After decolorization, use a plate and frame Ama filter to perform precision filtration to obtain a highly transparent decolorized liquid and waste carbon mud containing calcium carbonate, protein, lignin, and colloid.

[0011] (5) Continuous ion exchange: the decolorized material is passed through an ion exchange column to remove anionic and cationic impurities; (6) Evaporation and concentration: The material after ion exchange is sent to the evaporation system for concentration.

[0012] (7) Simulated moving bed chromatography separation: After purification and concentration, the feed liquid is separated and extracted by a simulated moving bed chromatography system to obtain a high-purity cellobiose dilute solution. The raffinate is used for the production of xylose and arabinose.

[0013] (8) Concentration: After the cellobiose extract is concentrated at low temperature by MVR, it enters the sugar boiling pot for further concentration, and the refractive index is controlled at 65%-75%; (9) Finished product: The concentrated cellobiose is crystallized, centrifuged, dried and packaged to obtain the finished product.

[0014] (10) Utilization of the raffinate: The raffinate produced in step (7) mainly contains functional rare sugars such as xylose, galactose, arabinose, and rhamnose. The raffinate is concentrated by evaporation at a vacuum degree of -0.05 to -0.09 MPa to a refractive index of 55-60%, and is canned to produce a functional prebiotic concentrate.

[0015] The above method for preparing cellobiose and comprehensive utilization of its by-products is preferably: Step (1) dilution: dilute the xylose mother liquor to a refractive index of 35-45%, and the sweet water used for dilution is the top water produced by the sugar column at the beginning of the ion exchange and the top water produced by the desugar column after the exchange column is saturated with adsorption. While using the sweet water recycling water, the sugar solution is recovered, the process yield is improved, which is beneficial to improving the complex sedimentation and separation filtration of lignin, colloid and calcium carbonate during the carbon explosion process, and is also beneficial to the efficient operation of the ion exchange.

[0016] Step (2) Enzymatic hydrolysis: adding xylanase to the diluted mother liquor, with the enzyme amount of 600-800 U / g, pH value of 5.0-6.0, enzymatic hydrolysis time of 90-100 min, and enzymatic hydrolysis temperature of 60-65°C.

[0017] Step (3) flocculation of carbon explosion: the amount of flocculant added is 30-80ppm, and the flocculant is chitosan.

[0018] Step (3) flocculation carbon explosion: after dilution, the mother liquor is heated to 55-67°C and alkalized with calcium hydroxide to adjust the pH value to above 10.

[0019] Step (3) flocculation carbon explosion: 99.9% food grade carbon dioxide gas is introduced to ensure sufficient reaction with the material. As the carbon dioxide is introduced and bubbled and micro-exploded, a complex precipitate is generated and the pH value is continuously reduced. The pH value of the carbon explosion endpoint is controlled at 4.5-6.5.

[0020] Step (4) Decolorization: Add powdered activated carbon to the material after carbon explosion and stir to decolorize. The amount of activated carbon added is 3-8‰, and the decolorization stirring time is 30-50 minutes.

[0021] Step (5) continuous ion exchange; the control conditions of the ion exchange column are: the output transmittance ≥ 75%; the conductivity ≤ 20us / cm; the pH value 3.0-6.5; the thin material with a refractive index of 0.5-5% is fed into step (1) as sweet water to ensure that the ion exchange refractive index is ≥ 30%.

[0022] Step (6) evaporation concentration: the material after ion exchange is sent to the evaporation system, and the vacuum degree is controlled to be -0.07Mpa to -0.095Mpa; the refractive index of the discharge material is controlled to be 45%-55%.

[0023] In step (7) of the sugar simulated moving bed chromatography separation, the feed refractive index is 45%-55%, and the turbidity is ≤1NTU; the arabinose refractive index in the extract is ≥15%; the transmittance is ≥90%, and the purity of cellobiose is 75%-90%.

[0024] Step (8) Finished product concentration: centrifugal control vacuum degree -0.06-0.09Mpa, refractive index 65%-75%; Step (9) The finished product is as follows: the crystallization is a gradient cooling crystallization, the cooling gradient is 1°C / h when the temperature is above 50°C, and the cooling gradient is 2°C / h when the temperature is below 50°C.

[0025] Due to the adoption of the above-mentioned technical solution, the present invention has the following beneficial effects: First: sweet water is used in the process of mother liquor dilution. While recycling water, sugar solution is recovered, which improves the process yield.

[0026] Second: During the ion exchange process, the separate collection of sweet water improves the refractive index of the output of continuous ion exchange, reduces the load of subsequent concentration, and reduces production costs.

[0027] Third: Adding flocculants before alkalization can pre-flocculate proteins and colloids, which greatly reduces the use of calcium hydroxide and carbon dioxide from carbon explosion.

[0028] Fourth: After alkalization, carbon dioxide gas is introduced to produce calcium carbonate, which is then precipitated together with the colloid, lignin and other impurities in the xylose mother liquor. This reduces the load of subsequent purification processes such as ion exchange, reduces production costs, and improves product quality.

[0029] Fifth: Since a large amount of colloidal impurities are precipitated in the form of complex precipitation, the impact of colloidal impurities on activated carbon is reduced, the decolorization efficiency is improved, the amount of activated carbon added is reduced, and the subsequent separation filtration speed is increased.

[0030] Sixth: Due to the carbon explosion process, the impurities and colloids in the material are completely removed and separated. The efficiency of subsequent chromatographic separation is greatly improved, and the refractive index and purity of the chromatographic output are improved, which reduces the production cost.

[0031] Seventh: Through xylan enzymatic hydrolysis, xylan and other pentose sugars are fully degraded into monosaccharides, while cellobiose is a disaccharide. Due to the large molecular difference, the chromatographic separation and extraction of cellobiose has higher separation efficiency, less water consumption, and lower overall production cost.

[0032] Eighth: The functional prebiotic concentrate obtained by concentrating the raffinate, as a high-value by-product, improves the economic benefits. DETAILED DESCRIPTION Example 1

[0033] (1) Dilution: dilute the xylose mother liquor with sweet water to a refractive index of 40% to meet the requirements of purification processes such as carbon explosion, filtration, and ion exchange; (2) Enzymatic hydrolysis: adding xylanase to the diluted mother liquor, with an enzyme dosage of 700 U / g, a pH value of 5.5-6.0, an enzymatic hydrolysis time of 100 min, and an enzymatic hydrolysis temperature of 60-63° C.; (3) Flocculation carbon explosion: the mother liquor after enzymatic hydrolysis in step (2) is heated to 65°C, 45 ppm of flocculant is added, and then calcium hydroxide is used to alkalize the mother liquor to a pH value of 10.0-11.0, and then carbon dioxide gas is introduced for bubbling and micro-explosion to produce calcium carbonate, while the impurities such as colloids and lignin in the complex xylose mother liquor are precipitated together with the calcium carbonate and precipitated; (4) Decolorization: Add 5‰ powdered activated carbon to the material after carbon explosion in step (3) for decolorization, stir for 40 min, and use a plate and frame Ama filter to perform precision filtration to obtain a highly transparent decolorized liquid and waste carbon mud containing calcium carbonate, lignin, and colloid; (5) Continuous ion exchange: The material decolorized in step (4) is passed through an ion exchange column to remove anionic and cationic impurities, and the output light transmittance is ≥75%; the conductivity is ≤20us / cm; the pH value is 3.0-6.5; all the thin materials with a refractive index of 0.5-5% are switched to sweet water to ensure that the ion exchange refractive index is ≥30%; (6) Evaporation and concentration: The material after ion exchange in step (5) is sent to the evaporation system for concentration, and the vacuum degree is controlled to be -0.07 MPa to -0.095 MPa, and the refractive index of the output material is 48% to 50%; (7) Simulated moving bed chromatography separation: the purified and concentrated feed liquid in step (6) is separated and extracted with cellobiose by a simulated moving bed chromatography system to obtain a high-purity cellobiose dilute solution, wherein the feed refractive index is 45%-55%, the turbidity is ≤1NTU, the purity of galactose in the extract is 85%-88%, the refractive index of arabinose in the raffinate is ≥15%, and the transmittance is ≥90%. (8) Concentration: The cellobiose solution in step (7) is concentrated by MVR low temperature and then put into the sugar boiling pot for further concentration. The vacuum degree is controlled at -0.06-0.09 MPa. The refractive index of the concentrated sugar mass is 70%-73%; (9) Finished product: The massecuite obtained in step (8) is cooled and crystallized, with the initial temperature being 73-74°C and the cooling gradient being 1°C / h. After the temperature is below 50°C, the cooling gradient is 2°C / h. After the cooling is completed, centrifugation is performed. The purity of the cellobiose crystals is 99.1%, the water content is 0.7%, and the refractive index of the mother liquor is 59%. The mother liquor is returned to step (6) for evaporation and concentration; (10) Utilization of the raffinate: The raffinate obtained in step (7) is evaporated to a refractive index of 55-60% under a vacuum degree of -0.05 to -0.09 MPa, and then bottled to produce a functional prebiotic concentrate. Example 2

[0034] (1) Dilution: dilute the xylose mother liquor with sweet water to a refractive index of 45% to meet the requirements of purification processes such as carbon explosion, filtration, and ion exchange; (2) Enzymatic hydrolysis: adding xylanase to the diluted mother liquor, the enzyme addition amount is 800 U / g, the pH value is 5.5-6.0, the enzymatic hydrolysis time is 100 min, and the enzymatic hydrolysis temperature is 60-63°C; (3) Carbon explosion: The mother liquor after enzymatic hydrolysis in step (2) is heated to 65°C, 50 ppm of flocculant is added, and then alkalized to a pH value of 10.0-11.0 using calcium hydroxide, and then carbon dioxide gas is introduced for bubbling and micro-explosion to produce calcium carbonate, while the impurities such as colloids and lignin in the xylose mother liquor are precipitated together with the calcium carbonate and precipitated; (4) Decolorization: Add 8‰ powdered activated carbon to the material after carbon explosion in step (3) for decolorization, stir for 40 min, and use a plate and frame Ama filter to perform precision filtration to obtain a highly transparent decolorized liquid and waste carbon mud containing calcium carbonate, lignin, and colloid; (5) Continuous ion exchange: The decolorized material in step (4) is passed through an ion exchange column to remove anionic and cationic impurities, and the output light transmittance is ≥80%; the conductivity is ≤20us / cm; the pH value is 4.0-6.5; the dilute material with a refractive index of 0.5-5% is completely replaced with sweet water to ensure that the ion exchange refractive index is ≥30%; (6) Evaporation and concentration: The material after ion exchange in step (5) is sent to the evaporation system for concentration, and the vacuum degree is controlled to be -0.07Mpa to -0.095Mpa, and the refractive index of the output material is 50%-55%; (7) Simulated moving bed chromatography separation: the purified and concentrated feed liquid in step (6) is separated and extracted with cellobiose by a simulated moving bed chromatography system to obtain a high-purity cellobiose dilute solution, wherein the feed refractive index is 45%-55%, the turbidity is ≤1NTU, the cellobiose purity in the extract is 88%-90%, the refractive index of arabinose in the raffinate is ≥15%, and the transmittance is ≥90%. (8) Concentration: The cellobiose solution in step (7) is concentrated by MVR low temperature and then enters the sugar boiling pot for further concentration. The vacuum degree is controlled at -0.06-0.09 MPa. The refractive index of the concentrated sugar mass is 73%-75%; (9) Finished product: The massecuite obtained in step (8) is cooled and crystallized, with the initial temperature being 73-74°C and the cooling gradient being 1°C / h. After the temperature is below 50°C, the cooling gradient is 2°C / h. After the cooling is completed, centrifugation is performed. The purity of the cellobiose crystals is 99.5%, the water content is 0.5%, and the refractive index of the mother liquor is 55%. The mother liquor is returned to step (6) for evaporation and concentration; (10) Utilization of the raffinate: The raffinate obtained in step (7) is evaporated to a refractive index of 55-60% under a vacuum degree of -0.05 to -0.09 MPa, and then bottled to produce a functional prebiotic concentrate. Example 3

[0035] (1) Dilution: dilute the xylose mother liquor with sweet water to a refractive index of 35% to meet the requirements of purification processes such as carbon explosion, filtration, and ion exchange; (2) Enzymatic hydrolysis: adding xylanase to the diluted mother liquor, with an enzyme dosage of 600 U / g, a pH value of 5.5-6.0, an enzymatic hydrolysis time of 100 min, and an enzymatic hydrolysis temperature of 60-63° C.; (3) Carbon explosion: The mother liquor after enzymatic hydrolysis in step (2) is heated to 58°C, alkalized to a pH of 10.0-11.0 using calcium hydroxide, and then carbon dioxide gas is introduced for bubbling and micro-explosion to produce calcium carbonate, while the impurities such as colloid and lignin in the xylose mother liquor are precipitated together with the calcium carbonate to precipitate; (4) Decolorization: Add 3‰ powdered activated carbon to the material after carbon explosion in step (3) for decolorization, stir for 40 min, and use a plate and frame Ama filter to perform precision filtration to obtain a highly transparent decolorized liquid and waste carbon mud containing calcium carbonate, lignin, and colloid; (5) Continuous ion exchange: The decolorized material in step (4) is passed through an ion exchange column to remove anionic and cationic impurities, and the output light transmittance is ≥85%; the conductivity is ≤20us / cm; the pH value is 4.0-6.5; the dilute material with a refractive index of 0.5-5% is completely replaced with sweet water to ensure that the ion exchange refractive index is ≥30%; (6) Evaporation and concentration: The material after ion exchange in step (5) is sent to the evaporation system for concentration, and the vacuum degree is controlled to be -0.07 MPa to -0.095 MPa, and the refractive index of the output material is 45% to 48%; (7) Simulated moving bed chromatography separation: the purified and concentrated feed liquid in step (6) is separated and extracted with cellobiose by a simulated moving bed chromatography system to obtain a high-purity cellobiose dilute solution, wherein the feed refractive index is 45%-55%, the turbidity is ≤1NTU, the cellobiose purity in the extract is 88%-90%, the refractive index of arabinose in the raffinate is ≥15%, and the transmittance is ≥90%. (8) Concentration: The cellobiose solution in step (7) is concentrated through MVR low temperature concentration and then put into a sugar boiling pot for further concentration. The vacuum degree is controlled at -0.06-0.09 MPa. The refractive index of the concentrated sugar mass is between 68% and 70%. (9) Finished product: The massecuite obtained in step (8) is cooled and crystallized, with the initial temperature being 73-74°C and the cooling gradient being 1°C / h. After the temperature is below 50°C, the cooling gradient is 2°C / h. After the cooling is completed, centrifugation is performed. The purity of the cellobiose crystals is 99.0%, the water content is 0.8%, and the refractive index of the mother liquor is 50%. The mother liquor is returned to step (6) for evaporation and concentration; (10) Utilization of raffinate: The raffinate is evaporated to a refractive index of 55-60% under a vacuum degree of -0.05 to -0.09 MPa, and then bottled to produce a functional prebiotic concentrate.

[0036] The parts of the present invention that are not described in detail are prior art. It is obvious to those skilled in the art that the present invention is not limited to the details of the above-mentioned exemplary embodiments, and the present invention can be implemented in other specific forms without departing from the spirit or basic characteristics of the present invention; therefore, no matter from which point of view, the embodiments should be regarded as exemplary and non-restrictive. The scope of the present invention is limited by the appended claims rather than the above description, and it is intended that all changes within the meaning and scope of the equivalent elements of the claims are included in the present invention.

Claims

1. A method for preparing cellobiose and comprehensive utilization of its by-products, characterized in that: The specific steps include: (1) Dilution: dilute the xylose mother liquor with sweet water; (2) Enzymatic hydrolysis: xylanase is added to the diluted mother liquor to decompose the polysaccharides in the mother liquor into xylose; (3) Flocculation carbon explosion: After enzymatic hydrolysis, the mother liquor is heated to a certain temperature to inactivate the xylanase, a flocculant is added for pre-sedimentation, and then calcium hydroxide is used for alkalization. Then, carbon dioxide gas is introduced for bubbling and micro-explosion to produce calcium carbonate. At the same time, the protein, colloid, and lignin impurities in the xylose mother liquor are complexed and precipitated together with calcium carbonate to precipitate; (4) Decolorization: Add powdered activated carbon to the material after carbon explosion for stirring and decolorization. After decolorization, use a plate and frame Ama filter to perform precision filtration to obtain a highly transparent decolorized liquid and waste carbon mud containing calcium carbonate, protein, lignin, and colloid; (5) Continuous ion exchange: the decolorized material is passed through an ion exchange column to remove anionic and cationic impurities; (6) Evaporation and concentration: The material after ion exchange is sent to the evaporation system for concentration; (7) Simulated moving bed chromatography separation: The purified and concentrated feed liquid is separated and extracted with cellobiose by a simulated moving bed chromatography system to obtain a high-purity cellobiose dilute solution and a raffinate; (8) Concentration: After the cellobiose extract is concentrated at low temperature by MVR, it enters the sugar boiling pot for further concentration, and the refractive index is controlled at 65%-75%; (9) Finished product: The concentrated cellobiose is crystallized, centrifuged, dried and packaged to obtain the finished product; (10) Utilization of the raffinate: The raffinate produced in step (7) is concentrated by evaporation to a refractive index of 55-60% under a vacuum degree of -0.05 to -0.09 MPa, and then canned to produce a functional prebiotic concentrate.

2. The method for preparing cellobiose and comprehensive utilization of its byproducts as claimed in claim 1, characterized in that: Step (1) dilution: dilute the xylose mother liquor to a refractive index of 35-45%, and the sweet water used for dilution is the top water produced by the sugar column at the beginning of ion exchange and the top water produced by the desugar column after the exchange column is saturated with adsorption.

3. The method for preparing cellobiose and comprehensive utilization of its byproducts as claimed in claim 1, characterized in that: Step (2) Enzymatic hydrolysis: adding xylanase to the diluted mother liquor, with the enzyme amount of 600-800 U / g, pH value of 5.0-6.0, enzymatic hydrolysis time of 90-100 min, and enzymatic hydrolysis temperature of 60-65°C.

4. The method for preparing cellobiose and comprehensive utilization of its byproducts as claimed in claim 1, characterized in that: Step (3) flocculation carbon explosion as described above: the amount of flocculant added is 30-80ppm, and the flocculant is chitosan; the mother liquor is heated to 55-67°C after dilution, and the pH value is adjusted to above 10 by alkalization with calcium hydroxide; food grade carbon dioxide gas with a purity greater than 99.9% is introduced, and the pH value of the carbon explosion endpoint is controlled to be 4.5-6.

5.

5. The method for preparing cellobiose and comprehensive utilization of its byproducts as claimed in claim 1, characterized in that: The material after carbon explosion is added with powdered activated carbon for stirring and decolorization. The amount of activated carbon added is 3-8‰, and the decolorization stirring time is 30-50 minutes.

6. The method for preparing cellobiose and comprehensive utilization of its byproducts as claimed in claim 1, characterized in that: Step (5) continuous ion exchange; the control conditions of the ion exchange column are: the output transmittance ≥75%, the ion exchange refractive index ≥30%, the conductivity ≤20us / cm, and the pH value 3.0-6.5; the thin material with a refractive index of 0.5-5% is sent to step (1) as sweet water.

7. The method for preparing cellobiose and comprehensive utilization of its byproducts as claimed in claim 1, characterized in that: Step (6) evaporation concentration: the material after ion exchange is sent to the evaporation system, and the vacuum degree is controlled to be -0.07Mpa to -0.095Mpa; the refractive index of the discharge material is controlled to be 45%-55%.

8. The method for preparing cellobiose and comprehensive utilization of its byproducts as claimed in claim 1, characterized in that: In step (7) of the sugar simulated moving bed chromatography separation, the feed refractive index is 45%-55%, and the turbidity is ≤1NTU; the arabinose refractive index in the extract is ≥15%; the transmittance is ≥90%, and the purity of cellobiose is 75%-90%.

9. The method for preparing cellobiose and comprehensive utilization of its byproducts as claimed in claim 1, characterized in that: Step (8) Concentration: Control the vacuum degree by centrifugation at -0.06-0.09 MPa and the refractive index at 65%-75%.

10. The method for preparing cellobiose and comprehensive utilization of its byproducts as claimed in claim 1, characterized in that: Step (9) The finished product is as follows: the crystallization is a gradient cooling crystallization, the cooling gradient is 1°C / h when the temperature is above 50°C, and the cooling gradient is 2°C / h when the temperature is below 50°C.