CN115109102A - Method for producing cellooligosaccharide-containing composition and cellooligosaccharide-containing composition - Google Patents

Abstract

An object of the present invention is to provide a method for producing a cellooligosaccharide-containing composition excellent in storage stability. To solve the above-mentioned problems is a method for producing a cellooligosaccharide-containing composition, comprising the step of hydrolyzing a raw material mixture containing cellulose and xylan in the presence of an acid catalyst. The total content of xylan in 100% by mass is 5 to 50% by mass of xylan.

Description

Method for producing cellooligosaccharide-containing composition and cellooligosaccharide-containing composition

technical field

The present invention relates to a method for producing a cellooligosaccharide-containing composition and a cellooligosaccharide-containing composition.

Background technique

Cellooligosaccharides are oligosaccharides in which glucose is bound together by β-1,4 bonds. In recent years, it has been discovered that it has functions such as moisturizing, inhibiting stickiness, imparting a cool feeling, reducing starch aging, and inhibiting protein denaturation. It is expected to be used in medicine, cosmetics, food, feed and other fields.

In particular, cellooligosaccharides having a degree of polymerization of glucose of 3 or more are expected to increase the above-mentioned functionality and impart new functionality.

Cello-oligosaccharide currently industrially used is produced by an enzymatic reaction, and its main components are glucose and cellobiose as a dimer (Patent Document 1).

As cello-oligosaccharide production techniques other than the enzymatic method, a hydrothermal treatment method (Patent Documents 2 to 4) and a hydrothermal treatment method with oxidized water containing hypochlorous acid (Patent Document 5) are known. In any of the patent documents, cellooligosaccharides are regarded as intermediate products in the process of breaking down cellulose into glucose.

In addition, a method of hydrolyzing a carbon catalyst and cellulose by mixing and pulverizing it by a hydrothermal synthesis method is known, and a method for producing cellooligosaccharide to obtain an oligosaccharide having a degree of polymerization of glucose as high as 6 has been disclosed. (Patent Document 6).

A method of partially hydrolyzing cellulose by a semi-dry conversion method using a phosphoric acid catalyst is known (Non-Patent Document 1). The selectivity of this method is relatively high, and cellooligosaccharides with a degree of polymerization of 7 or more can be obtained.

However, in the methods described in Patent Documents 1 to 5, the hydrolysis reaction proceeds to glucose excessively, and is inefficient as a method for obtaining cellooligosaccharide. In the method described in Patent Document 6, in order to increase the conversion rate of cellulose, the hydrolysis reaction proceeds to glucose, and in order to increase the yield of cellooligosaccharide, very precise temperature control and the like are required. The cello-oligosaccharide method is not efficient.

【Existing technical documents】

【Patent Literature】

[Patent Document 1] Japanese Patent Laid-Open No. 2009-189293

[Patent Document 2] Japanese Patent Laid-Open No. 2011-068578

[Patent Document 3] International Publication No. 2011/036955

[Patent Document 4] International Publication No. 2012/128055

[Patent Document 5] Japanese Patent Application Laid-Open No. 2006-320261

[Patent Document 6] International Publication No. 2017/104687

【Non-patent literature】

[Non-Patent Document 1] Bull.Chem.Soc.Jpn.2020, 93, 273-278

SUMMARY OF THE INVENTION

【The problem to be solved by the invention】

On the other hand, as a method for producing cellooligosaccharide having a relatively high degree of polymerization (for example, the method described in Non-Patent Document 1), the obtained cellooligosaccharide has insufficient solubility in water, and it is easy to be stored for a long time. Disadvantages of poor precipitation and storage stability.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a method for producing a cellooligosaccharide-containing composition having a relatively high degree of polymerization and excellent storage stability.

【Means to solve the problem】

The inventors of the present invention have repeatedly conducted intensive studies in order to solve the above-mentioned problems, and as a result, came up with the idea of hydrolyzing cellulose containing a predetermined ratio of xylan as a raw material in the presence of an acid catalyst.

As a result, a method for producing a cellooligosaccharide-containing composition has been found by making the xylan containing cellulose and xylan in an amount of 100% by mass relative to the total content of the cellulose and the xylan. The above-mentioned problem can be solved by hydrolyzing a mixture containing 5 to 50 mass % of sugar in the presence of an acid catalyst.

That is, the present invention includes the following aspects [1] to [8].

[1]. A method for producing a cellooligosaccharide-containing composition, comprising the step of hydrolyzing a raw material mixture containing cellulose and xylan in the presence of an acid catalyst, the raw material mixture containing And the total content of the xylan in 100 mass % is 5-50 mass % of the xylan.

[2]. The method for producing a cellooligosaccharide-containing composition according to [1], wherein the raw material mixture contains 7 to 40 mass % with respect to 100 mass % of the total content of the cellulose and the xylan % of the xylan.

[3]. The method for producing a cellooligosaccharide-containing composition according to [1] or [2], wherein the acid catalyst is selected from the group consisting of sulfuric acid, sulfurous acid, hydrochloric acid, perchloric acid, nitric acid, nitrous acid and phosphoric acid at least one acid or a partially neutralized salt thereof.

[4]. The method for producing a cellooligosaccharide-containing composition according to [3], wherein the acid catalyst is phosphoric acid or a partially neutralized salt thereof.

[5]. The method for producing a cellooligosaccharide-containing composition according to [4], wherein the acid catalyst is phosphoric acid.

[6]. The method for producing a cellooligosaccharide-containing composition according to any one of [1] to [5], comprising subjecting the raw material mixture to a pulverization treatment in the presence of the acid catalyst for hydrolysis step.

[7]. The method for producing a cellooligosaccharide-containing composition according to [6], wherein the pulverization treatment is performed by using a planetary ball mill or a vibration mill.

[8]. A cellooligosaccharide-containing composition produced by hydrolyzing a raw material mixture containing cellulose and xylan in the presence of an acid catalyst, the xylan in the raw material mixture Its content is 5 to 50 mass % relative to 100 mass % of the total content of the cellulose and the xylan.

【Invention effect】

According to the method for producing a cellooligosaccharide-containing composition of the present invention, a cellooligosaccharide-containing composition excellent in storage stability can be produced even if the degree of polymerization is relatively high (the degree of polymerization is 3 to 6).

Description of drawings

FIG. 1 is a ¹ H-NMR chart of the hydrolyzate produced in Example 1. FIG.

2 is a ¹ H-NMR chart of the hydrolyzate produced in Example 2. FIG.

3 is a ¹ H-NMR chart of the hydrolyzate produced in Comparative Example 1. FIG.

4 is a ¹ H-NMR chart of the hydrolyzate produced in Comparative Example 2. FIG.

Detailed ways

Embodiments of the present invention will be described below. In addition, the embodiment described below is only for showing a representative example of the present invention, and is not limited thereto.

The method for producing a cellooligosaccharide-containing composition according to one embodiment includes the step of hydrolyzing a raw material mixture comprising cellulose and xylan in the presence of an acid catalyst, relative to the cellulose and the xylan in the raw material mixture. The total content of 100% by mass of the xylan contains 5-50% by mass of the xylan.

＜Raw material mixture＞

In the method for producing a cellooligosaccharide-containing composition according to one embodiment, a raw material mixture (hereinafter, sometimes referred to as a "cellulose-xylan mixture") containing cellulose and xylan is used as a raw material.

Cellulose and xylan, known as biomass, are not fossil resources, but organic resources of plant origin.

Examples of cellulosic biomass include wood-based materials such as cotton, wood-based pulp, kenaf, hemp, small-diameter wood, thinning wood, sawdust, wood chips, waste paper, newspapers, wrapping paper, paper towels, toilet paper, and corrugated paper. Biomass; and herbaceous biomass such as bagasse, switchgrass, elephant grass, corncob, rice straw, and wheat straw, which can be used alone or in combination of two or more. For example, it is possible to use water-insoluble cellulose obtained by bleaching these biomass by chlorine treatment to produce chemical pulp (whole cellulose) and subjecting this chemical pulp to alkali treatment to remove hemicellulose.

Cellulose typically exhibits crystallinity by hydrogen bonding of two or more cellulose molecules. In one embodiment, cellulose having such crystallinity can be used as a raw material. In this embodiment, in order to increase the hydrolysis rate, it is preferable to perform a treatment for lowering the crystallinity such as preliminarily pulverizing to reduce the crystallinity before use. The crystallinity-reduced cellulose may be partially reduced in crystallinity, or the crystallinity may be substantially or completely disappeared. The method of the crystallinity reduction treatment is not particularly limited, but it is preferably a crystallinity reduction treatment of cellulose molecules capable of cleaving the above-mentioned hydrogen bonds and at least partially generating one chain. By using cellulose containing at least a part of cellulose molecules of one chain as a raw material, the efficiency of hydrolysis can be greatly improved.

The crystallinity reduction treatment of raw cellulose includes a method of physically cutting hydrogen bonds between cellulose molecules to obtain a single chain of cellulose molecules, such as ball milling, which is pre-crushed (refer to Zhao et al, Energy & Fuels, 20, 807 (2006)), and a method for obtaining a single chain of cellulose by chemically cleaving hydrogen bonds between cellulose molecules using phosphoric acid treatment without applying compressive shear stress (refer to Zhang et al, Biomacromolecules, 7, 644 (2006)). The crystallinity reduction treatment of cellulose may not be a treatment until the crystallinity of the cellulose completely disappears, but may be a treatment for partially reducing the crystallinity of the cellulose before the treatment. By using the cellulose subjected to these treatments as a raw material, the efficiency of hydrolysis can be greatly improved.

Further, as the treatment for reducing the crystallinity of the raw material cellulose, for example, pressurized hot water treatment (see Hayashi et al, J.Jpn.Inst.Energy, 83, 805 (2004), Sasaki et al, Ind.Eng. Chem. Res., 39, 2883 (2000) et al).

Xylan refers to a polysaccharide in which D-xylose residues are β-1,4 bound or β-1,3 bound. In addition to xylose, the sugar constituting xylan may contain arabinose, glucuronic acid, 4-0-methylglucuronic acid, glucose, galactose, and the like.

The xylan is preferably pre-disintegrated by applying compressive shear stress prior to hydrolysis. In order to disintegrate xylan by applying compressive shear stress, a compression shear disintegrator can be used. A compression shearing type shredder is a machine which can apply both a compressive stress and a shearing stress, for example, a vibrating rod mill (rod mill), a vibrating ball mill, etc. are mentioned. Among them, a vibrating rod mill is preferable from the viewpoint of production efficiency. The rod is not particularly limited, but is preferably 0.1 to 100 mm in outer diameter, more preferably 0.5 to 50 mm. The filling rate of the rod (the apparent volume of the rod with respect to the volume of the stirring part of the vibration mill) varies depending on the model, but is preferably 10 to 97%, and more preferably 15 to 95%.

The crushing conditions such as the crushing time and the number of revolutions of the crusher can be appropriately set in order to form a desired crushed product. From the viewpoint of obtaining a high hydrolysis rate, it is preferable that the crystallinity of the disintegrated xylan is low.

Xylan can be pre-crushed prior to pre-crushing by compressive shear stress. There is no particular limitation on the method of rough pulverization. For example, as a pulverizer, a knife-type pulverizer such as a grinder and a barrel cutter, an impact pulverizer such as a hammer mill, or a colloid can be used. Grinding mill and the like.

In the cellulose-xylan mixture, the content of xylan is 5 to 50% by mass relative to 100% by mass of the total content of cellulose and xylan. By containing 5 mass % or more of xylan, the solubility of the hydrolyzate in water can be improved, and a cellooligosaccharide-containing composition excellent in storage stability can be produced. If the content of xylan is less than 50% by mass, the cellooligosaccharide-containing composition that is the target can be obtained in a sufficient yield. In the mixture of cellulose and xylan, the content of xylan is preferably 7 to 40% by mass, more preferably 10 to 30% by mass, and still more preferably 100% by mass of the total content of cellulose and xylan 15 to 25 mass %.

In the cellulose-xylan mixture, the content of xylan was determined by the method described in the examples described later. Specifically, the mixture used as a raw material is hydrolyzed to monosaccharide units with an aqueous sulfuric acid solution or the like, and the content of glucose and xylose in the product is analyzed, thereby determining the content of xylan in the mixture used as a raw material relative to The total content of cellulose and xylan is 100% by mass. However, it is assumed here that xylan consists only of xylose.

In addition to cellulose and xylan, other components (for example, other polysaccharides, etc.) may be contained in the cellulose-xylan mixture. The amount of the other components is preferably 10% by mass or less, more preferably 5% by mass or less, relative to 100% by mass of the mixture.

The cellulose and xylan contained in the cellulose/xylan mixture may be mixed before being introduced into the reactor for the hydrolysis reaction, or may be mixed in the reactor for the hydrolysis reaction. As a cellulose-xylan mixture, a commercial product containing cellulose and xylan can be purchased and used. For example, in cellulose produced from cellulosic biomass in which xylose skeletons are mixed in addition to glucose skeletons as raw materials, xylan may not be completely removed and may be mixed in cellulose. Such commercially available cellulose can be used as the cellulose-xylan mixture as long as the content of xylan is 5 to 50% by mass relative to 100% by mass of the total content of cellulose and xylan.

<Hydrolysis reaction>

In the method for producing a cellooligosaccharide-containing composition according to one embodiment, cellooligosaccharide is produced by hydrolyzing a cellulose-xylan mixture in the presence of an acid catalyst.

As the acid catalyst, well-known acids known in the past can be used. Specifically, at least one acid selected from sulfuric acid, sulfurous acid, hydrochloric acid, perchloric acid, nitric acid, nitrous acid, and phosphoric acid or a partially neutralized salt thereof may be used. Examples of the partially neutralized salt of the acid include monopotassium dihydrogen phosphate, monoammonium dihydrogen phosphate, potassium hydrogen sulfate, and the like. The acid catalyst is preferably phosphoric acid or a partially neutralized salt thereof, more preferably phosphoric acid.

The amount of the acid catalyst used is preferably such that the mass ratio of the cellulose-xylan mixture to the acid catalyst is: (cellulose-xylan mixture)/(acid catalyst)=2 to 100, more preferably: (fiber The amount of cellulose xylan mixture)/(acid catalyst)=4 to 20, more preferably, the amount of (cellulose xylan mixture)/(acid catalyst)=5 to 12. When the mass ratio of the cellulose-xylan mixture to the acid catalyst is 100 or less, the hydrolysis proceeds at a rate that is not problematic in practical use. When the mass ratio of the cellulose-xylan mixture to the acid catalyst is 2 or more, side reactions such as dehydration reaction and cleavage of carbon-carbon bonds can be suppressed during hydrolysis.

The mass of the cellulose-xylan mixture in the present disclosure is the net mass (dry mass) after removing the moisture contained in the raw material. Usually, cellulose and xylan contain physically adsorbed water, so the amount of attached water is analyzed, and from the mass of the cellulose-xylan mixture after removal of the water, the cellulose-xylan mixture relative to the Mass ratio of acid catalyst. As a method for analyzing the amount of adhering moisture, there is a quantitative method in which the cellulose-xylan mixture used as a raw material is put into a constant temperature dryer at 100°C to 150°C and dried until there is no mass loss. In order to prevent the influence of side reactions such as dehydration reaction at the time of drying, it is preferable to use a vacuum dryer to dry and quantify at a relatively low temperature. The mass of the acid catalyst is also the mass (dry mass) of the real acid catalyst.

As described above, the water physically adsorbed in the cellulose-xylan mixture before hydrolysis is about 1 to 12 mass %. In addition, many acid catalysts such as hydrochloric acid and phosphoric acid contain water as a usual commercial form. Therefore, even if water is not added, hydrolysis can be performed using the water physically adsorbed in the cellulose-xylan mixture and the water contained in the acid catalyst. In general, even if water is not added, the amount of water is often sufficient. However, for a cellulose-xylan mixture with a high degree of dryness, water may be added for hydrolysis.

The cellulose-xylan mixture contains about 1 to 12 mass % of physisorbed moisture, regardless of whether water is added or when water is to be added. Therefore, the amount of water in the hydrolysis reaction is preferably the amount of water physically adsorbed in the cellulose-xylan mixture and water contained in the acid catalyst (which is also included when water is further added) relative to the amount of water in the cellulose-wood mixture. 100 parts by mass of the net mass (dry mass) of the polysaccharide mixture is 0.1 parts by mass to 15 parts by mass, and more preferably 0.5 parts by mass to 8 parts by mass. When it is 15 parts by mass or less, not only a sufficient hydrolysis rate can be obtained, but also it is possible to prevent inoperability due to the fixation and adhesion to the device. Moreover, when it is 0.1 mass part or more, side reactions, such as a dehydration reaction, can be suppressed.

In the production method of the cellooligosaccharide-containing composition of one embodiment, a method (mechanochemical method) of hydrolyzing a cellulose-xylan mixture by applying a mechanical external force by pulverization treatment is preferably used.

Examples of the pulverizing device used for pulverization include rotary ball mills such as pot mills, tubular mills, and cone mills, eddy jet mills, impact jet mills, fluidized bed jet mills, and wet jet mills. Pulverizers, grinding mixers, angle grinders and other shearing mills, mortars, stone mortars and other colloid mills, hammer mills, cage mills, needle mills, pulverizers, sieve mills, turbine mills, centrifugal separation mills, etc. Impact pulverizer, vibrating mill that pulverizes the medium by vibrating the drum; put the medium and raw materials into a tank with stirring blades, and make it rotate and pulverize; and, using rotation and Planetary ball mill of the type of orbital motion, etc.

The pulverizing device is preferably a ball mill, a vibration mill or a stirring mill, which can apply a compressive force to the cellulose-xylan mixture and a tensile stress in both directions of the main chain. The pulverizing device is more preferably a planetary ball mill, a rotary ball mill, a vibration mill or a stirring mill, and still more preferably a planetary ball mill or a vibration mill.

At the laboratory level, planetary ball mills are preferably used. It is better to use vibrating mill in industry. The vibrating mill does not rotate the drum (pulverizing drum) in which the pulverizing medium is inserted, but moves the medium in the drum by vibrating the drum, so that it can take about 1/10 to 1/20 of the time compared with the drum rotary ball mill. Crushed inside. The stirring mill moves the medium by rotating the stirring blade instead of the drum, and can pulverize in about 1/10 to 1/20 of the time compared to the drum rotary ball mill.

The pulverization process may be performed continuously or intermittently. In order to suppress the temperature rise of the object to be processed accompanying the pulverization treatment, it is preferable to perform the pulverization treatment intermittently. When the pulverization process is performed intermittently, the optimum value differs greatly depending on the pulverization device. For example, in the case of a planetary ball mill, every 5 to 15 minutes of the pulverization process is carried out for 5 to 15 minutes. The rest time is performed by repeating such a cycle. When the pulverization treatment is performed continuously, it is preferable to perform the pulverization treatment while maintaining an appropriate temperature by cooling the pulverizing device by providing a jacket or the like.

When hydrolyzing the cellulose/xylan mixture using a pulverizing device such as a ball mill, the hydrolysis may be performed while reducing the crystallinity of cellulose or xylan by pulverization, or the cellulose reduction may be performed in advance as described above. Or the crystallinity of xylan, and then add acid catalyst for hydrolysis. When cellulose or xylan is preliminarily pulverized by a Henschel mixer and then pulverized by a ball mill or the like, the acid catalyst can be mixed from the prepulverization stage.

In the method for producing a cellooligosaccharide-containing composition according to an embodiment, when hydrolysis is performed without pulverization, as a method without pulverization, for example, kneading treatment using a pressure kneader can be exemplified. method, and a method of reacting using an extrusion molding machine after kneading in a kneader.

The temperature of hydrolysis is preferably from normal temperature to 110°C, and more preferably from 50°C to 100°C. If the temperature is equal to or higher than normal temperature, the progress of the decomposition will not be slow, and the time required for the decomposition will not be excessively prolonged. In order to accelerate the decomposition rate, the hydrolysis can also be carried out at high temperature. When the temperature of hydrolysis is 110° C. or lower, side reactions such as dehydration reaction can be suppressed. Since shear heat generation may be large depending on the reaction apparatus, it is preferable to control the hydrolysis temperature by repeating the cycle with a rest time as described above, or by passing cooling water into the jacket of the reaction apparatus.

The hydrolysis time depends on the reaction apparatus used, but is usually preferably 2 hours to 150 hours, more preferably 5 hours to 80 hours, still more preferably 10 hours to 60 hours, and particularly preferably 15 hours to 40 hours. When the hydrolysis time is 2 hours or more, the decomposition of the cellulose-xylan mixture can be accelerated. If the time for hydrolysis is 150 hours or less, a hydrolyzate can be obtained more efficiently. In the present disclosure, when the pulverization treatment is performed intermittently in the case of performing the hydrolysis by the pulverization treatment, the time of the hydrolysis refers to the net pulverization treatment time after the rest time is removed.

The progress of the hydrolysis of the cellulose-xylan mixture can be confirmed by collecting a small amount of the object to be treated over time and measuring the amount of the water-soluble component contained in the collected product.

<Other steps>

The method for producing a cellooligosaccharide-containing composition according to one embodiment may include the following steps as necessary, in addition to the step of performing the above-mentioned hydrolysis reaction.

[Extraction step]

The method for producing a cellooligosaccharide-containing composition according to one embodiment may include a step of adding water to a reactant to extract a water-soluble component after the above-mentioned hydrolysis reaction. When the amount of water used in the hydrolysis is small, the reaction product is in a solid state, so it is preferable to perform the extraction step.

The mass ratio of the amount of water added to the reactant is preferably: (addition amount of water)/(reactant)=0.5 to 100, more preferably 1 to 20, and still more preferably 2 to 10. If the mass ratio is 0.5 or more, the soluble components in the reactant can be efficiently dissolved, and if the mass ratio is 100 or less, the container for dissolution will not be too large, so the efficiency is good.

The water to be added to the reactants is not particularly limited, but distilled water is usually used. In addition to distilled water, salt-containing solutions, buffers, and the like can also be used. In the range that does not affect the dissolution of the soluble components in the reactants, an organic solvent that can be mixed with water can also be added.

The separation of the water-soluble component and the solid component can be carried out by a generally used method for removing the solid component from the suspension. Filtration can be performed using, for example, filter paper, filter cloth, membrane filter, filter press, centrifugal filter, cross-flow filter, or the like, or natural sedimentation or centrifugal sedimentation.

In order to obtain high-purity cellooligosaccharide, the following purification operation can be performed: after removing the solid content from the reactant, ethanol or the like is added to the aqueous solution containing the water-soluble component to reprecipitate the cellooligosaccharide, and the obtained precipitate is redissolved. In water, ethanol reprecipitation was repeated.

[neutralization step]

The manufacturing method of the cellooligosaccharide containing composition of one Embodiment may have the process of adding a basic compound and neutralizing a reactant after the said hydrolysis reaction. Since the acid catalyst used for the hydrolysis remains in the reactant obtained by the above-mentioned hydrolysis reaction, the acid catalyst can be neutralized by adding a basic compound.

In the case where the above-described extraction step is performed after the hydrolysis reaction, the neutralization step may be performed after the extraction step, and may be performed simultaneously with the extraction step.

The basic compound is preferably at least one selected from potassium salts, phosphates, ammonium salts and ammonia.

In the case of using a potassium salt as the basic compound, for example, potassium hydroxide, potassium carbonate, potassium formate, potassium acetate, potassium ethoxide, monopotassium dihydrogen phosphate, dipotassium monohydrogen phosphate, tripotassium phosphate, potassium amide, etc. can be used . Among them, potassium hydroxide, potassium carbonate, dipotassium monohydrogen phosphate and tripotassium phosphate are preferred.

When a phosphate is used as the basic compound, monopotassium dihydrogen phosphate, dipotassium monohydrogen phosphate, tripotassium phosphate, diammonium hydrogen phosphate, triammonium phosphate and the like can be used. Thus, the phosphate can be both potassium or ammonium salts.

When an ammonium salt is used as the basic compound, tetramethylammonium hydroxide, tetraethylammonium hydroxide, ammonium carbonate, diammonium hydrogen phosphate, triammonium phosphate, ammonium nitrate, ammonium sulfate, and the like can be used. Among them, diammonium hydrogen phosphate and ammonium sulfate are preferred.

When ammonia is used as the basic compound, ammonia water is preferably used.

The temperature of the neutralization reaction is preferably 0°C to 50°C, more preferably 5°C to 40°C, and still more preferably 20°C to 30°C in order to prevent the product of the hydrolysis reaction from reacting excessively. The neutralization reaction itself is relatively fast, but in the presence of insoluble matter derived from the raw material, it is necessary to sufficiently diffuse the acid. Therefore, the time for the neutralization reaction is preferably 0.1 to 10 hours, more preferably 0.5 to 5 hours. More preferably, it is 1 hour to 3 hours. As an apparatus for neutralization reaction, a normal stirring tank can be used without special need. When using hydrochloric acid or sulfuric acid as an acid catalyst, it is preferable to use a stirring tank with a corrosion-resistant lining such as glass.

In the case of performing the neutralization step, since precipitation may be caused by changing the pH to the neutral side, it is preferable to separate the solid portion by filtration after the neutralization reaction. When filtering is performed after the neutralization reaction, after the water-soluble components are extracted in the above-mentioned extraction step, the operation of separating (filtering) the water-soluble components and the solid components may be omitted.

The separation of the solid part after the neutralization reaction can be carried out by a generally used method of removing the solid part from the suspension. Filtration can be performed using, for example, filter paper, filter cloth, membrane filter, filter press, centrifugal filter, cross-flow filter, or the like, or natural sedimentation or centrifugal sedimentation.

<Product of hydrolysis reaction>

As a production method for producing a cellooligosaccharide-containing composition by hydrolysis of cellulose, a carbon catalyst method and an acid catalyst method are known.

The carbon catalyst method is a method of hydrolyzing cellulose in the presence of a carbon catalyst such as activated carbon and water. In this method, as shown in the following formula (1), only linear cellooligosaccharide is produced.

(In formula (1), m and n represent the degree of polymerization.)

The acid catalyst method is a method of hydrolyzing cellulose in the presence of an acid catalyst. In this method, in addition to the reaction represented by the above-mentioned formula (1), a reaction to produce a branched cello-oligosaccharide as represented by the following formula (2) occurs. That is, a cellooligosaccharide having a branched backbone can be produced by reacting the hydroxyl group at the 6-position with cellulose. This branched body is more soluble in water than the straight chain body.

(In formula (2), m, n, x and y represent the degree of polymerization.)

In the method for producing a cellooligosaccharide-containing composition according to one embodiment, in the acid catalyst method, the reaction is performed using a cellulose-xylan mixture containing xylan in a predetermined ratio as a raw material. While not being bound by any theory, in this reaction, as shown in the following formula (3), the hydroxyl group at the 6-position and xylan (or xylose, the hydrolyzate of xylan, not shown in formula (3) ) also react to form branched cello-oligosaccharides incorporating xylan residues (or xylose residues) in the cellulose backbone. As described above, it is presumed that the water solubility of the branched cello-oligosaccharide to which xylan residues or xylose residues are bound is further increased.

(In the formula (3), m, n, x and y represent the degree of polymerization.)

Although the details are not clear, it is presumed that, in the method for producing a cellooligosaccharide-containing composition, as described above, xylan residues or xylose residue-bound branches are partially generated as described above. Since it is converted into cellooligosaccharide, the solubility in water is improved, the generation of turbidity in the cellooligosaccharide aqueous solution can be suppressed, and the storage stability can be improved.

The number average molecular weight of the cellooligosaccharide produced by the method for producing a cellooligosaccharide-containing composition of one embodiment is preferably 340 to 1640, more preferably 420 to 1320, and still more preferably 500 to 990. The number-average molecular weight of cellooligosaccharide was determined by the method described in the examples described later. In addition, when a xylose unit is contained in the cellooligosaccharide, the number average molecular weight of the cellooligosaccharide is a molecular weight which also contains a xylose unit.

The ratio of α-1,6-glycosidic bonds (hereinafter, sometimes referred to as "the " The degree of branching") is preferably 1 to 50%, more preferably 3 to 40%, still more preferably 5 to 30%, particularly preferably 5 to 20%. The "polymeric bond" in cellooligosaccharide refers to a bond that connects monosaccharides to each other to form an oligosaccharide, and typically refers to a glycosidic bond. The degree of branching is determined from the area ratio of the NMR spectrum by the method described in the examples described later. Note that the degree of branching is a value including the ratio of α-1,6-glycosidic bonds bound to xylan residues or xylose residues as represented by the above formula (3).

【Example】

Hereinafter, the present invention will be described more specifically based on examples, but the present invention is not limited to these examples.

<1. Raw material analysis>

The polysaccharides used as raw materials were hydrolyzed into monosaccharide units by the following method, and the composition of the raw materials was analyzed.

100 mg of polysaccharides and 1 mL of a 72 mass % sulfuric acid aqueous solution were mixed and stirred at 30° C. for 1 hour. Next, 28 mL of water was added to the mixture, and the mixture was stirred at 120° C. for 1 hour, cooled and filtered. By analyzing the obtained filtrate by HPLC, the glucose content and the xylose content in the filtrate were obtained.

[HPLC analysis conditions]

Columns: 3 Shodex (registered trademark) GF-210 (produced by Showa Denko Co., Ltd.)

Eluent: 0.2M aqueous acetic acid

Column temperature: 40℃

Eluent flow rate: 0.6mL/min

Detector: Differential refractive index detector

The composition of the polysaccharide used as a raw material was determined from the glucose content and xylose content obtained by HPLC analysis. Additionally, it is assumed that xylan is composed of xylose only. The results are shown below.

· Celeros アーボセル B600 (manufactured by レッテンマイヤー Co., Ltd.): 80% by mass of cellulose, 20% by mass of xylan

Abel (crystalline fine powder cellulose produced by Merck): 99% by mass of cellulose, 1% by mass of xylan

- Xylan (Xylan from シグマアルドリッチ Co., Ltd., derived from an epidermis layer): 100% by mass of xylan

<2. Production of oligosaccharides>

[Example 1] Production of cellooligosaccharide-containing composition by acid catalyst method using cellulose as a raw material

As a raw material mixture, Celeros アーボセル B600 (manufactured by レッテンマイヤー Co., Ltd.) was used.

3.79 kg of the above-mentioned raw material mixture (water content 3.4 mass %, dry mass 3.66 kg, xylan content: 20 mass %) was mixed with a Henschel mixer (device name: FM 20C/I, manufactured by Japan Cox Industries Ltd.) 0.53 kg of 85% phosphoric acid aqueous solution (special-grade reagent produced by Fuji Filmie Wako Pure Chemical Industries, Ltd.) was mixed. The mass ratio of the cellulose·xylan mixture to the acid catalyst was: (cellulose·xylan mixture)/(acid catalyst)=8.1. The mixing conditions were the number of revolutions at 1400 rpm and the aeration at 0.4 m ³ /hour.

350 g of this mixture was transferred to a vibration mill (device name: MB-1 type, manufactured by Chuo Kakkei Co., Ltd.), and pulverized at 75° C. for 72 hours while hydrolyzing. The grinding conditions were a total amplitude of 8 mm, a rotation number of 1000 rpm, and carbon steel balls of φ3/4 inches were used.

The pulverized product was taken out from the vibration mill and separated from the balls, and 300 g of the pulverized product was transferred to a dissolving device (5 L container). 2817 g of ion-exchanged water was added, and the mixture was stirred at 25° C. for 1 hour using a stirrer, スリーワンモータ (registered trademark). Thereby, the water-soluble component was dissolved, and the extract of the hydrolyzate was obtained.

To this extract, 61 g of a 48% potassium hydroxide aqueous solution was added, and the mixture was stirred at 25° C. for 1 hour using a stirrer. 122 g of perlite Pallite #31 (manufactured by Showa Chemical Industry Co., Ltd.) was added as a filter aid, and filtered using a filter press (KST-293-20, manufactured by Adbantech Toyo Co., Ltd.) to obtain 2,533 g of a filtrate.

The pH of the filtrate was 6.8, and sulfuric acid hydrolysis was carried out by the same method as the raw material analysis, and the obtained monomer was analyzed by HPLC. As a result, it contained 167 g of cellulose hydrolyzate and 42 g of xylan hydrolyzate.

The obtained filtrate was diluted with water so that the sugar concentration (the total concentration of the cellulose hydrolyzate and the xylan hydrolyzate) was 5% by mass, and it was used as a sample solution in the turbidity measurement described later.

The number average molecular weight and branching degree of the hydrolyzate in the filtrate were determined by the following methods. In addition, the measurement was performed without separating the xylan hydrolyzate contained in the filtrate.

[Analysis method of number average molecular weight]

The number average molecular weight is obtained by GPC (gel permeation chromatography) analysis using an HPLC (high performance liquid chromatography) apparatus.

Each of the standard samples prepared under the conditions shown in Table 1 was irradiated with ultrasonic waves for 5 minutes, and the dispersed and dissolved standard samples were allowed to stand overnight, and then a 0.45 μm PTFE membrane filter (model: 25HP045AN, Adbantech Toyo Co., Ltd. was used) Co., Ltd.) was filtered and a standard sample was prepared. "Criterion 1" and "Criterion 2" were used in the analysis of cellooligosaccharide. In Table 1, "Mp" represents the peak molecular weight.

Analysis samples were prepared by diluting the filtrate in 1 g of water at a ratio of 0.10 g, respectively.

Table 1

As an analyzer, GPC-LS (manufactured by Agilent, 1260 Infinity) was used, and the measurement was performed under the following analysis conditions, and the number average molecular weight of all the peaks of each analysis sample was determined.

(analysis condition)

Column: Shodex (registered trademark) SB-G 6B (guard column) + SB802.5H

Q (analytical column) × 3

Column temperature: 40℃

Eluent: 30v/v% acetonitrile + 70v/v% water 0.2M aqueous acetic acid

Flow rate: 0.5mL/min

Injection volume: 20μL

Detector: Differential Refractometer (RI)

[Analysis method of branching degree]

The degree of branching was determined using an NMR (nuclear magnetic resonance) apparatus under the conditions shown below.

(NMR conditions)

Equipment: Bruker AVANCE 500 (500MHz)

Measurement method: ¹ H-NMR, ¹³ C-NMR, ¹³ C-DEPT135, HSQC

Locking solvent: D ₂ O

Internal standard: TSP-d ₄ (sodium trimethylsilyl propionate) = 0 ppm

temperature: room temperature

Sample preparation: powder sample (50 mg)/D ₂ O (1 mL) + TSP-d ₄ (5 mg)

The filtrate was vacuum-dried into a powder sample in advance, and a measurement sample was prepared by the following method. Accurately weigh 50 mg of the powder sample, add 1 mL of D ₂ O to a 50 mL sample bottle to dissolve it, shake it with an ultrasonic cleaner for 5 minutes, dry it with a vacuum dryer (30°C), and accurately weigh it again. amount to calculate the amount of dehydration. TSP-d ₄ (5 mg) and D ₂ O (1 mL) were added again, and after shaking with an ultrasonic cleaner for 5 minutes, the filtrate was filtered with a 0.45 μm filter, ディスポフィルター (Model: 25HP045AN, manufactured by Adbantech Toyo Co., Ltd.), and the filtrate was charged. A 5 mmφ NMR sample tube was used for NMR measurement immediately after sampling.

The degree of branching is based on the area ratio of the spectrum of α-1,6-H1" detected at 4.9 to 5.0 ppm and the spectrum of "β-1,4-H1" detected at 4.4 to 4.6 ppm. calculated by the formula.

Branching degree=(α-1,6-H1)÷[(α-1,6-H1)+(β-1,4-H1)]×100(%)

The number-average molecular weight of the hydrolyzate produced in Example 1 was 800 (the number-average degree of polymerization in terms of glucose units was 4.8), and the degree of branching was 14%. 1 shows the ¹ H-NMR spectrum of the hydrolyzate produced in Example 1.

[Example 2] Production of cellooligosaccharide-containing composition by acid catalyst method using cellulose and xylan as raw materials

Except for the use of 3.02 kg of Abel (a crystalline fine powder cellulose produced by Merck) (3.1 mass % moisture content, 2.93 kg of dry mass), and 0.81 of xylan (produced by シグマアルドリッチ, derived from the epidermis) 0.81 kg (water content 9.8 mass %, dry mass 0.73 kg) was used as the raw material mixture (xylan content: 21 mass %), the hydrolysis reaction, the extraction of the hydrolyzate, and the filtration of the extract were carried out in the same manner as in Example 1 to obtain filtrate. The mass ratio of the cellulose·xylan mixture to the acid catalyst was: (cellulose·xylan mixture)/(acid catalyst)=8.1.

The pH of the filtrate was 6.8, and sulfuric acid hydrolysis was carried out by the same method as the raw material analysis. The obtained monomer was subjected to HPLC analysis, and the results showed that it contained 166 g of cellulose hydrolyzate and 42 g of xylan hydrolyzate.

The obtained filtrate was diluted with water so that the sugar concentration (the total concentration of the cellulose hydrolyzate and the xylan hydrolyzate) was 5% by mass, and it was used as a sample solution in the turbidity measurement described later.

By the method described in Example 1, the number average molecular weight and branching degree of the hydrolyzate in the filtrate were determined. As a result, the number-average molecular weight was 780 (the number-average degree of polymerization in terms of glucose units was 4.7), and the degree of branching was 18%. FIG. 2 shows the ¹ H-NMR spectrum of the hydrolyzate produced in Example 2. FIG.

[Comparative Example 1] Cello-oligosaccharide-containing composition produced by acid catalyst method using cellulose as a raw material

The hydrolysis reaction, the extraction of the hydrolyzate, and the extract were carried out in the same manner as in Example 1, except that 3.91 kg (water content 3.1%, dry mass 3.79 kg) of Abecel (crystalline fine powder cellulose produced by Merck) was used as the raw material filtration to obtain a filtrate. The mass ratio of the cellulose-xylan mixture to the acid catalyst was: (cellulose-xylan mixture)/(acid catalyst)=8.4.

The pH of the filtrate was 6.8, sulfuric acid hydrolysis was performed by the same method as the analysis of the raw material, and the obtained monomer was analyzed by HPLC. As a result, 207 g of cellulose hydrolyzate was contained. The obtained filtrate was diluted with water so that the sugar concentration (the concentration of cellulose hydrolyzate) was 5 mass %, and it was set as the sample solution in the turbidity measurement mentioned later.

By the method described in Example 1, the number average molecular weight and branching degree of the hydrolyzate in the filtrate were determined. As a result, the number-average molecular weight was 810 (the number-average degree of polymerization in terms of glucose units was 4.9), and the degree of branching was 12%. FIG. 3 shows the ¹ H-NMR spectrum of the hydrolyzate produced in Comparative Example 1. FIG.

[Comparative Example 2] Production of a cellooligosaccharide-containing composition by a carbon catalyst method using cellulose as a raw material

10 g of Abercel (crystalline fine powder cellulose manufactured by Merck) and 1.5 g of activated carbon BA50 (manufactured by Ajinomoto Co., Ltd.) and 2,000 g of alumina balls with a diameter of 1.5 cm were placed in a ceramic pot mill with a capacity of 3,600 mL, and set The reaction raw material was obtained after being treated at 60 rpm for 48 hours on a table-top pot mill rotary table (manufactured by Nitto Science Co., Ltd., table-top pot mill (Zuoshang ポットミル), model ANZ-51S). In addition, the temperature is started at room temperature, and the temperature rise due to shear heat generation is left unrestricted.

Next, 0.374 g of the reaction raw materials and 40 mL of water were put into a high-pressure reactor (internal volume: 100 mL, an autoclave manufactured by Orabotech Co., Ltd., manufactured by Hastelloy Hestelloy C22), followed by stirring at 600 rpm at 10 to 30° C./min (Average temperature increase rate 11.3°C/min) The reaction temperature was heated to 230°C, then the heating was stopped immediately, and the reactor was air-cooled at 10 to 30°C/min (average temperature drop rate 16.7°C/min) to prepare a reaction solution.

Next, the supernatant liquid recovered from the reaction solution by the centrifuge was freeze-dried to obtain cellooligosaccharide powder. The obtained powder was dissolved in water so that the sugar concentration (the concentration of cellulose hydrolyzate) was 5 mass %, and it was used as a sample solution in the turbidity measurement described later.

The number average molecular weight and degree of branching of the hydrolyzate were obtained by the method described in Example 1. As a result, the number-average molecular weight was 780 (the number-average degree of polymerization in terms of glucose units was 4.7), and the degree of branching was 0%. FIG. 4 shows the ¹ H-NMR spectrum of the hydrolyzate produced in Comparative Example 2. FIG.

<3. Observation of turbidity and measurement of turbidity>

For each of the sample solutions obtained in Examples 1 to 2 and Comparative Examples 1 to 2, the presence or absence of turbidity and the measurement of turbidity were performed at the time of production and after storage for 7 days. The results are shown in Table 2.

The preservation of the sample solution was performed by filling a 50 mL glass screw-top bottle container with 40 mL of the sample solution and leaving it to stand still in a thermostat set to 30°C.

The measurement of turbidity used the following method. A sufficiently dispersed sample solution (Sample 1) and a sample solution (Sample 2) obtained by filtering Sample 1 through a 0.45 μm membrane were prepared, and each sample was placed in a 1 cm square tank, and the absorbance at a wavelength of 660 nm was measured. From the measured absorbance, the turbidity was calculated by the following formula.

Turbidity = (absorbance of sample 1) - (absorbance of sample 2)

Table 2

As can be seen from the results in Table 2, in Examples 1 and 2 in which a mixture of cellulose and xylan containing xylan at a predetermined ratio was used as a raw material, the sample solution was not cloudy even after storage for 7 days. Excellent storage stability. On the other hand, Comparative Example 1 using cellulose containing almost no xylan as a raw material was cloudy after storage for 7 days, and Comparative Example 2 was cloudy immediately after production.

industry availability

According to the method for producing a cellooligosaccharide-containing composition of the present invention, a cellooligosaccharide-containing composition excellent in storage stability can be produced even if the degree of polymerization is relatively high.

Claims (8)

1. A method for producing a cellooligosaccharide-containing composition, comprising a step of hydrolyzing a raw material mixture containing cellulose and xylan in the presence of an acid catalyst, the raw material mixture containing The total content of the xylan in 100% by mass is 5-50% by mass of the xylan. 2 . The method for producing a cellooligosaccharide-containing composition according to claim 1 , wherein the raw material mixture contains 7 to 40 mass % of the total content of the cellulose and the xylan in 100 mass %. 3 . the xylan. 3. The manufacture method of the cello-oligosaccharide-containing composition as claimed in claim 1 or 2, wherein the acid catalyst is at least one selected from the group consisting of sulfuric acid, sulfurous acid, hydrochloric acid, perchloric acid, nitric acid, nitrous acid and phosphoric acid an acid or a partially neutralized salt thereof. The method for producing a cellooligosaccharide-containing composition according to claim 3, wherein the acid catalyst is phosphoric acid or a partially neutralized salt thereof. 5 . The method for producing a cellooligosaccharide-containing composition according to claim 4 , wherein the acid catalyst is phosphoric acid. 6 . 6 . The method for producing a cellooligosaccharide-containing composition according to claim 1 , comprising a step of subjecting the raw material mixture to a pulverization treatment in the presence of the acid catalyst to hydrolyze the composition. 7 . 7 . The method for producing a cellooligosaccharide-containing composition according to claim 6 , wherein the pulverization treatment is performed by using a planetary ball mill or a vibration mill. 8 . 8. A cellooligosaccharide-containing composition produced by hydrolyzing a raw material mixture containing cellulose and xylan in the presence of an acid catalyst, the content of the xylan in the raw material mixture It is 5-50 mass % with respect to 100 mass % of the total content of the said cellulose and the said xylan.

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