JP2000236899A - Production of xylose and xylooligosaccharide - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for industrially and efficiently producing xylose and xylooligosaccharide in a shortened facility by extracting xylose and xylooligosaccharide from a xylan-containing natural product. SOLUTION: This method for producing xylose and xylooligosaccharide comprises removing a component previously extracted by hot water heated to >=110 deg.C to <=200 deg.C from xylan-containing natural product (e.g. sugar cane) and treating the resultant water-insoluble residue with hot water heated to <=200 deg.C.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to a method for producing xylose and xylooligosaccharide by treating a xylan-containing natural product with hot water under special conditions.

[0002]

2. Description of the Related Art Conventionally, as a method for producing xylose and xylo-oligosaccharide, a xylan-containing natural product has been used for about 130 minutes.
After steaming or explosion treatment at a temperature of ℃ or more, after extracting with water to obtain an extract containing xylose and xylooligosaccharide, decolorizing treatment by a combination of activated carbon treatment and ion exchange resin treatment, etc., high purity Methods for obtaining xylose and xylooligosaccharides are known.

[0003] However, the extract obtained by the above method contains lignin-decomposing components, water-soluble components in raw materials,
Since coloring substances such as hemicellulose decomposition components are mixed in a large amount as impurities, 1) decolorization is difficult 2)
The amount of activated carbon and ion exchange resin used becomes enormous 3)
Irreversible adsorption of the dye to the anion exchange resin is unavoidable, so the life of the anion exchange resin is short. 4) Part of xylose and xylooligosaccharide is adsorbed to activated carbon or ion exchange resin, and the yield is reduced. Had the problem of.

[0004] In order to improve these problems, an extract obtained by treating a xylan-containing natural product with hot water is prepared in advance.
B) Chromatographic separation (Japanese Patent Laid-Open No. 1-254692)
And b) ultrafiltration (JP-A-61-285999)
A method is disclosed in which impurities mixed in are efficiently removed, and then decolorization treatment is performed using activated carbon or an ion-exchange tree. However, a) is a method in which the ion-excluding action of the cation exchange resin is used to fractionate into an elution section containing xylose and xylooligosaccharide and an elution section of coloring impurities, and the xylose and xylooligosaccharide are completely separated from the coloring impurities. It is difficult to separate colored impurities.Efficient removal of colored impurities results in loss of xylose and xylo-oligosaccharides, resulting in reduced yield, or a large amount of xylose and xylo-oligosaccharides. There is a tendency for impurities to be mixed. Further, b) is a method of separating xylose and xylo-oligosaccharide having relatively low molecular weight from coloring impurities having relatively high molecular weight by the molecular sieving action of the ultrafiltration membrane. Because there are also those with similar molecular weights, if a membrane with a small molecular weight cut-off is used, the high molecular side of the xylo-oligosaccharide cannot pass through the membrane,
When the yield of xylo-oligosaccharide is reduced, or when a membrane having a large molecular weight cut-off is used, the low molecular side of the colored impurities tends to pass through the membrane and be mixed into xylose and xylo-oligosaccharide. However, it has not been a sufficient method for efficiently removing colored impurities while maintaining the yield of xylo-oligosaccharides.

In Japanese Patent Application Laid-Open No. Hei 6-197800, the raw material is limited to sasa, but after removing the organic solvent such as acetone or alcohol or components extracted with cold or hot water from the raw material, the remainder is removed. Water content of 30% to 6%
A method for extracting xylo-oligosaccharides by adjusting the pressure to a range of 0% and subjecting the xylo-oligosaccharide to heat treatment under pressure with saturated steam is disclosed. According to this method, by pretreating the raw material to remove organic acid salts such as potassium acetate and sodium acetate,
Secondary decomposition of xylan is suppressed, and xylo-oligosaccharides can be extracted with high yield and high purity as compared with the case without pretreatment. However, under the pretreatment conditions, the easily decomposable lignin contained in the raw material is not decomposed and eluted, and when subjected to heat treatment under pressure, the lignin-decomposing component is mixed in the xylo-oligosaccharide to remove the impurities. It took a lot of effort to do so. For the above reasons, a method of extracting xylose and xylooligosaccharide from xylan-containing natural products with high purity is desired.

[0006]

DISCLOSURE OF THE INVENTION The present invention provides a method for industrially and efficiently producing xylose and xylooligosaccharides by extracting xylose and xylooligosaccharide from a xylan-containing natural product with a high degree of purity by using a shortened facility. The aim is to provide a method.

[0007]

Means for Solving the Problems The present inventors have conducted intensive studies in order to solve the above-mentioned problems, and as a result, when extracting a sugar solution containing xylose and xylo-oligosaccharide as main components from a natural product containing xylan, hot water was used. By treating under specific conditions using only xylose and xylo-oligosaccharides extracted, it is possible to suppress the decomposition and to significantly reduce the contamination of impurities such as lignin decomposition components and water-soluble components in the raw materials. , Xylose and xylooligosaccharide can be extracted with high purity, and the present invention has been completed.

That is, the present invention provides (1) a water-insoluble residue obtained by removing components extracted with hot water of 110 ° C. or more and 140 ° C. or less from natural products containing xylan, A method for producing xylose and xylooligosaccharide, which is characterized by treating with water; (2) a method for producing xylose and xylooligosaccharide according to (1), wherein the xylan-containing natural product is sugarcane. To provide.

Hereinafter, the present invention will be described in detail. As raw materials used in the present invention, natural products containing xylan, for example, broadleaf trees such as birch and beech, and agricultural wastes such as corn rice ears, cottonseed shells, sugarcane baccas, sugarcane pips, and beet pulp can be used. Among these raw materials, sugarcane pis, which has a low lignin content and can easily extract xylose and xylooligosaccharides under mild conditions, is particularly preferable. The shape of these raw materials is not particularly limited, but those which are pulverized into chips, fibers or the like are preferably used to facilitate the extraction operation. The hot water treatment of the xylan-containing natural product in the present invention can be performed, if necessary, in combination with explosion crushing, which is a known technique. When performing the hot water treatment, it is preferable to perform the treatment with stirring to facilitate the extraction.

In the present invention, the pretreatment of xylan-containing natural products with hot water varies depending on the raw materials used.
It is necessary to carry out at a temperature of 110 ° C. or more and 140 ° C. or less. 1
When the temperature is lower than 10 ° C., the elution of impurities such as easily decomposable lignin and water-soluble components contained in the raw material is insufficient,
When the temperature exceeds 140 ° C., the xylan component is eluted, and the yield of xylitol finally obtained is undesirably reduced. The time required for the pretreatment is usually 10 minutes or more and 120 minutes or less, preferably 15 minutes or more and 60 minutes or less,
Especially preferably, it is 20 minutes or more and 40 minutes or less. If the time is less than 10 minutes, the elution of the impurities is insufficient, and no further elution of the impurities is observed even when the operation is performed for more than 120 minutes.

The amount of water to be added to the xylan-containing raw material is usually 1 to 16 times the dry weight of the raw material,
Preferably 3 times or more and 14 times or less, more preferably 5 times or more.
It is not less than double and not more than 12 times. When the amount of water is less than 1 time, the dissolution of the impurities does not sufficiently occur, and the impurities cannot be efficiently removed, which is not preferable. On the other hand, when the amount of water exceeds 16 times, the concentration of protons derived from the released acetic acid decreases, and the decomposition of easily decomposable lignin does not sufficiently occur, which is not preferable because it is mixed in the subsequent operation process.

The xylan-containing natural product subjected to the above-mentioned hot water treatment may be subjected to stirring treatment with water at 100 ° C. or lower, if necessary, to sufficiently extract impurities. At this time, water may be newly added in order to perform stirring smoothly. After the treatment under the above conditions, impurities eluted by a centrifuge, a filter or the like are separated and removed to obtain a residue containing necessary xylan in high purity. The obtained residue is preferably washed with water to sufficiently remove impurities. Although the pretreated xylan-containing raw material varies depending on the raw material used, it is usually subjected to hot water treatment at a pretreatment temperature of 200 ° C. or higher to extract xylose and xylo-oligosaccharide. When the treatment temperature is lower than the pretreatment temperature, there are almost no extractable components. When the treatment temperature is higher than 200 ° C, the hardly decomposable lignin and cellulose contained in the raw material are hydrolyzed and eluted together with xylose and xylooligosaccharide. Not preferred.

The hot water treatment time is usually 20 minutes or more and 180 minutes or less, preferably 40 minutes or more and 120 minutes or less. 20
If the time is shorter than x minutes, xylose and xylooligosaccharide are not sufficiently eluted, which is not preferable. If it is longer than 180 minutes, the decomposition of xylose and xylo-oligosaccharides generated in the reaction system becomes remarkable, which is not preferable. The amount of water to be added to the pretreated xylan-containing raw material is usually 1 to 16 times, preferably 3 to 14 times, more preferably 5 times the dry weight of the raw material. More than 12 times the amount. If the amount is less than 1 time, it is insufficient to completely dissolve the hydrolyzed xylose and xylooligosaccharide in water. It is not preferable because the concentration of the derived protons is reduced, the water solubilization due to partial hydrolysis of xylan does not sufficiently occur, and the yields of xylose and xylo-oligosaccharide are reduced.

After performing the above extraction operation, if necessary,
It is also possible to sufficiently extract water-soluble xylose and xylooligosaccharide by stirring with water at a temperature of 100 ° C. or lower. At this time, water may be newly added for smooth stirring. After performing the above-mentioned extraction operation, the residue is separated and removed from the extract using a centrifuge, a filter, or the like, whereby an extract having high-purity xylose and xylooligosaccharide as main components can be obtained.

The aqueous solution containing xylose and xylooligosaccharide as main components obtained by the above-mentioned extraction method is subjected to ordinary decolorization and desalting treatment such as activated carbon treatment and cation-anion exchange resin treatment, if necessary, to obtain xylose. Further, a purified sugar solution containing no impurities can be easily obtained without loss of xylooligosaccharide. The xylose and xylo-oligosaccharide purified as described above can be used as it is in foods and the like. It is also possible to separate and use fractions containing at least one of xylose and xylo-oligosaccharides of any degree of polymerization using column chromatography or ultrafiltration.

[0016]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in more detail by way of examples. In addition, the measurement of the content of the lignin decomposition | disassembly component melt | dissolved in aqueous solution was performed based on JIS-P8008 using the sample which absolutely dried the dissolved solid content in aqueous solution under vacuum. The exchange capacity of the anion exchange resin was measured by titrating the resin with a standard hydrogen chloride solution (Wako Pure Chemical Industries, Ltd.) using phenolphthalein as an indicator in the presence of a 15-fold weight of 0.5N aqueous sodium chloride solution. And asked.

[0017]

EXAMPLES (Example 1) 100 g of air-dried corn cob
And 1.0 kg of water in a 2 L autoclave.
Heat treatment was performed at 40 ° C. for 40 minutes. Then, the extract is filtered off while washing with water, and the residue 87 containing xylan in high purity is removed.
g was obtained. (Pretreatment) 87 g of the residue obtained by the pretreatment and 1.0 kg of water
The mixture was placed in an L autoclave and heated at 160 ° C. for 90 minutes. Next, the residue was filtered off, and the obtained extract was concentrated under reduced pressure to obtain 210 g of an extract having a solid concentration of 10% by weight.
Obtained. (Main treatment) Add 50 g of powdered activated carbon to 50 g of the extract, and add 50 g
, And the activated carbon was filtered off.

The activated carbon-treated extract was passed through a column filled with 20 g of Amberlite IRA410 (Organo Co., Ltd.) to obtain a colorless and transparent aqueous solution containing xylose and xylooligosaccharide. For comparison, when using a corn cob without pretreatment, extraction and subsequent purification were performed under the same conditions as above, but the obtained aqueous solution containing xylose and xylooligosaccharide was It was slightly yellow (Comparative Example 1).

Table 1 shows the ratio of the sugar component and the lignin-decomposing component to the solid content in the extract, and the reduced ion exchange capacity of the ion exchange resin when the extract was treated with the ion exchange resin. As shown in Table 1, the purity of the xylose component with respect to the extracted solid content was 44.1 in Comparative Example 1, but was as high as 68.9% in the case of the present invention. Further, in Comparative Example 1, the lignin component was remarkably mixed, and the color was not completely removed by 0.05 g of activated carbon and 20 g of an anion exchange resin. From these facts, it can be seen that according to the present invention, the xylose component can be extracted with high purity, and therefore, the subsequent purification load is significantly reduced.

(Example 2) The colorless and transparent aqueous solution containing xylose and xylooligosaccharide obtained in Example 1 was
The solution was passed through an ultrafiltration membrane YM5 (Amicon Grace Japan) having a molecular weight cutoff of 5000 at a pressure of 3.8 kg / cm2. The permeated solution is again subjected to ultrafiltration membrane Y having a molecular weight cutoff of 1,000.
3.8 using M2 (Amicon Grace Japan)
It was filtered at a pressure of kg / cm2. Xylooligosaccharides containing xylobiose and xylotriose as main components were obtained from the retentate.

(Example 3) 100 g of air-dried sugarcane pips
And 1.0 kg of water in a 2 L autoclave,
Heat treatment was performed at 30 ° C. for 30 minutes. Then, the extract is filtered off while washing with water, and the residue 85 containing xylan in high purity is removed.
g was obtained. (Pretreatment) 85 g of the residue obtained by the pretreatment and 1.0 kg of water
It was placed in an L autoclave and heated at 150 ° C. for 60 minutes. After cooling to 70 ° C., 500 g of water was added and the mixture was stirred for 2 hours. Then, the residue was filtered off, and the obtained extract was concentrated under reduced pressure, and 220 g of an extract having a solid concentration of 10% by weight was obtained.
Obtained. (Main treatment) Add 50 g of powdered activated carbon to 50 g of the extract, and add 50 g
, And the activated carbon was filtered off.

The activated carbon-treated extract was passed through a column filled with 20 g of Amberlite IRA410 (Organo Co., Ltd.) to obtain a colorless and transparent aqueous solution containing xylose and xylooligosaccharide. For comparison,
When the pretreatment condition was 80 ° C. for 2 hours (Comparative Example 2) or the main treatment condition was 210 ° C. for 20 minutes (Comparative Example 3),
Extraction and subsequent purification operations were performed under the same conditions as described above.
Table 2 shows the ratio of the sugar component and the lignin-decomposing component to the solid content in the extract, and the reduced ion exchange capacity of the ion exchange resin when the extract was treated with the ion exchange resin.

As shown in Table 2, in the present invention, 68.9%
And xylose components can be extracted with high purity, but in Comparative Example 2, the removal of impurities by the pretreatment is insufficient, so that a large amount of easily decomposable lignin is mixed therein.
The purity is as low as 9%, and in Comparative Example 3,
Since the hardly decomposable lignin and cellulose are hydrolyzed and mixed into the processing solution, the purity is low at 46.0%. Therefore, as shown in Table 2, the capacity of the ion exchange resin required for the decolorizing treatment in Comparative Examples 2 and 3 is three times or more as compared with the case of the present invention. From these facts, it can be seen that according to the present invention, the xylose component can be extracted with high purity, and the subsequent purification load is significantly reduced.

[0024]

[Table 1]

[0025]

[Table 2]

Example 4 100 g of air-dried cotton hulls and 80 water
0 g was placed in a 2 L autoclave and heated at 120 ° C. for 40 minutes. Next, the extract was separated by filtration while washing with water to obtain 86 g of a residue containing xylan. 86 g of the obtained residue and 800 g of water were placed in a 2 L autoclave, and
After heat treatment at 50 ° C for 90 minutes, it is cooled to 70 ° C,
500 g of water was added and stirred for 1 hour. Next, the residue was filtered off, and the obtained extract was concentrated under reduced pressure to obtain a solid content of 5%.
640 g of a weight% extract were obtained. Thereafter, the extract was treated in the same manner as in Example 1. As a result, the xylose component could be extracted with high purity, and the purification load of the ion exchange resin was significantly reduced.

Example 5 100 g of air-dried birch chips and 1.0 kg of water were placed in a 2 L autoclave and heated at 135 ° C. for 2 hours.
Heat treatment was performed for 5 minutes. Next, the extract was separated by filtration while washing with water to obtain 91 g of a residue containing xylan. A treated product obtained by subjecting 91 g of the obtained residue to explosion treatment at a temperature of 175 ° C. for 1 minute and 1.0 kg of water were placed in a 2 L autoclave,
After heating at 170 ° C. for 90 minutes, the mixture was cooled to 70 ° C. and stirred for 2 hours. Next, the residue was filtered off, and the obtained extract was concentrated under reduced pressure to obtain an extract 4 having a solid concentration of 5% by weight.
30 g were obtained. Thereafter, the extract was treated in the same manner as in Example 1. As a result, the xylose component can be extracted with high purity,
Moreover, the purification load of the ion exchange resin was significantly reduced.

[0028]

EFFECT OF THE INVENTION Xylose and xylooligosaccharide can be extracted with high purity by treating a xylan-containing natural product with hot water under specific conditions, so that xylose and xylooligosaccharide having high purity can be efficiently produced. This is extremely useful as a method for performing

Claims (2)

[Claims] 1. A water-insoluble residue obtained by removing components extracted with hot water at 110 ° C. or more and 140 ° C. or less from natural xylan-containing products is treated with hot water at a temperature of 200 ° C. or more. A method for producing xylose and xylooligosaccharide. 2. The method for producing xylose and xylooligosaccharide according to claim 1, wherein the natural product containing xylan is sugarcane.