JPS61285999A - Production of xylose and xylooligosaccharide - Google Patents

Abstract

PURPOSE:To obtain colorless, transparent syrup having mild sweetness, by hydrolyzing partially an aqueous solution of xylan and passing it through an ultrafilter having fraction molecular weight in a specific range. CONSTITUTION:An aqueous solution of a xylosaccharide obtained by extraction with hot water is treated with industrial cellulase and the reaction is stopped at a stage wherein a largest amount of xylodisaccharide - xylohexaose is produced. This partially hydrolyzed saccharide solution is passed through an ultrafilter having 500-2,000 preferably 500-1,000 fraction molecular weight, a solution containing xylosaccharides with a little coloring is obtained and colorless, transparent syrup is obtained by a conventional procedure through active carbon treatment, ion exchange treatment and concentration.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing xylose and xylooligosaccharides from xylan-producing plant materials. Xylooligosaccharide is a mixture of xylose and xylose di- to heptasaccharides, and is a syrup-like substance with a mild sweet taste. Xylooligosaccharides are difficult to absorb into the human body, so they can be used as low-calorie sweeteners and food ingredients. In addition, the reduced xylo-lower class II obtained by hydrogenating it has increased heat resistance and alkali resistance, so it can be used as a non-coloring food material and a chemical raw material.

Methods for producing xylopolymer III include a method in which xylanase is directly applied to xylan, a method in which xylan in plant materials is directly solubilized in water, and the like.

The former is described in Japanese Patent Publication No. 46-12936. In this method, highly pure xylan is reacted with filamentous fungal xylase and hydrolysis is stopped midway through to obtain xylo-minor class II.

The raw materials used must be highly purified xylan obtained by extracting plant materials with alkali, etc., and then thoroughly refining them, and because xylanase is not currently produced on an industrial scale and at an industrial price. It is not suitable as a manufacturing method. Regarding the latter method of water-solubilizing xylan in plant materials, there are methods of extraction with alkali, extraction with mineral acid, and extraction with hot water (including steam). In the alkali extraction method, xylan is extracted as a polymer.
Also, when the extract is neutralized with acid, xylan precipitates. Therefore, in this case, the method of extraction with acid cannot be called water-solubilization, and the hydrolysis rate is fast, so it is extremely difficult to stop the process at the stage of xylo-minor Ii. On the other hand, with the method of extraction with hot water, if you choose appropriate extraction conditions, you can obtain an aqueous solution of xylosaccharides, so you can get very few xylosaccharides! It is considered to be most suitable for similar manufacturing methods. This hot water extraction method is described in detail in JP-A-53-44640. However, the disadvantage of this method is that the obtained sugar solution and xylose crystals are strongly colored, which limits its use.

The present inventors conducted intensive research to obtain a colorless and transparent syrup from this xylan aqueous solution extracted with hot water, and as a result, it became clear that the conventional decolorization method has the following disadvantages.

(1) Method using activated carbon When a large amount of activated carbon is used, decolorization can be achieved. However, the amount of activated carbon required is about the same as the solid content in the aqueous solution, and the activated carbon contains xylosaccharides, especially xylose. The above components are adsorbed, resulting in a decrease in yield, which is undesirable.

(2) Method using ion exchange resin Various ion exchange resins, especially ion exchange resins for decolorization, have decolorization ability, but their decolorization capacity is not small, and colored components of polymers are difficult to decolor during regeneration and accumulate in the resin. The disadvantage is that the lifespan is shortened.

(3) Method using an ultrafiltration membrane When a membrane with a high molecular weight cutoff (2000 or more) was used, there was little decolorizing effect.

In addition, a membrane with a small molecular weight cutoff (less than 500) had a decolorizing effect, but only low-molecular-weight xylosaccharides could pass through it, resulting in a decrease in yield and was unsuitable.

The present inventors have obtained a molecular weight cutoff of 200 as shown in (3) above.
We discovered that ultrafiltration membranes with a molecular weight cut-off of 0 or less do not allow color components to pass through.Based on this, we partially hydrolyzed an aqueous xylan solution and then passed it through an ultrafiltration membrane with a molecular weight cutoff of 500-2000. They discovered what could be achieved and completed the present invention.

A more detailed explanation of the present invention is as follows.

The starting material of the present invention is cottonseed husks with a high xylan content.

Regarding the hot water extraction method, raw materials such as corn cobs, buckwheat hulls, bakasu 2 and hardwoods such as birch are preferred.

fi+ Method of heating water and raw materials in a sealed container.

(2) There is a method in which raw materials are placed in a closed container, heated under saturated steam at a temperature of 2QQ°C or higher, and then rapidly released into the air, followed by extraction after explosion treatment. Specifically, raw materials and appropriate processing conditions are shown. In the case of raw materials such as cottonseed husks and corn cobs, the ill method is preferable, and the temperature is preferably 150°C to 170°C and the processing time is preferably 30 to 120 minutes. If the temperature is lower than this, the extraction yield will be low, which is not preferable. Also, if the temperature is too high, hydrolysis will occur rapidly, producing a large amount of xylose, and at the same time coloration will occur due to thermal decomposition, which is undesirable.In the case of wood such as birch, chips are often used, so method (2) is used. is suitable.

The 2011M aqueous solution obtained by hot water extraction is a yellow-brown liquid with a high degree of polymerization, so it cannot pass through an ultrafiltration membrane as it is, so it needs to be reduced in molecular weight.

Xylanase is normally used as a method for converting xylan into low-molecular-weight xylan.

Xylanase has not yet been produced industrially.

A feature of the present invention is the use of industrial cellulase, which is industrially produced at low cost. This is because the extract does not contain cellulose and commercially available cellulases either contain mfi xylanase as an impurity or have a xylan degrading function.

The conditions for hydrolysis using industrial cellulase are preferably as mild as possible with a small amount of enzyme. And Kishiro 2~7I! The reaction is stopped when the largest amount of In addition, in this step, it is completely hydrolyzed to xylose and can be used for the production of crystalline xylose.

Next, the feature of the present invention is that by passing the sugar solution partially hydrolyzed with cellulase through an ultrafiltration membrane, a liquid containing a small amount of xylo-m with little coloring can be obtained.0 The ultrafiltration membrane used in the present invention is Fraction molecular weight is 500-2000, preferably 500-2000
It is 1000. Thereafter, the syrup was treated with activated carbon, treated with an ion exchange resin, and concentrated using conventional methods to obtain a colorless and transparent syrup with a mild sweet taste.

This will be explained below using examples.

Example 1 60 g of cottonseed husks and 300 g of water were placed in a stainless steel airtight container with an internal volume of 550 μl and equipped with a stirrer, and heated at 170° C. for 60 minutes. After cooling, filter the contents.

Furthermore, the residue was washed with 100 ml of water, and the filtrate and washings were combined to obtain 352 g of sugar solution (A-1).

(Hereinafter, the liquid in this step will be referred to as A-) Next, 300+ sg of cellulase TAP-4 (manufactured by Amano Seiyaku ■) was added to this sugar solution A-1, and the pH was adjusted to 4.5 with dilute caustic soda or dilute hydrochloric acid. , 1 partial hydrolysis was carried out at a temperature of 45° C. for 3 hours to obtain sugar solution B-1.

(Hereinafter, the liquid in this step will be referred to as B-) Next, an ultrafiltration membrane UH-1 with a molecular weight cutoff of 1000 was placed in a small ultrafiltration device RO-3 (specially manufactured by Bioengineering).
(manufactured by Toyo Roshi) and passed sugar solution B-1 under a pressure of 3 kg/- to obtain 300 g of sugar solution C-1.

(Hereinafter, the liquid in this step will be expressed as C-) 0.5 g of activated carbon (Shirasagi, manufactured by Takeda Pharmaceutical Company Limited) was added to this sugar solution C-1, stirred at 40°C for 1 hour, and then filtered. Passed through 10ml of cation exchange resin 5K-18 (manufactured by Mitsubishi Chemical Industries, Ltd.) and then through 10ml of anion exchange resin -^-30 (manufactured by Mitsubishi Chemical Industries, Ltd.), and concentrated to 70%. 13.6g of colorless and transparent sugar solution D
-1 was obtained. (Hereinafter, the liquid in this step will be referred to as D-.) Table 1 shows the results of analyzing the cono sugar liquids A-1, 8-1, C-1, and D-1.

(Space below) Example 2 The same method as in Example 1 was used except that the ultrafiltration membrane in Example 1 was an ultrafiltration membrane 0H-05 (manufactured by Toyo Roshi) with a molecular weight cut off of 500. 300 g Sugar solution C-2 and 11.3
A colorless and transparent sugar solution D-2 was obtained. Sugar solution C-2 and D-
The analysis results of 2 are shown in Table 2.

Table 2 Example 3 The method of Example 1 was followed except that the xylan-containing raw material of Example 1 was ground corn cob.326
g of sugar solution A-3, B-3, 280 g of sugar solution C-3 and 1
0.2 g of a colorless and transparent sugar solution D-3 was obtained.

Table 3 shows the results of analyzing sugar solutions A-3, B-3, C-3 and D-3.

(Left below) Table 3 Example 4 Cellulase T was added to sugar solution B-1 prepared in the same manner as in Example 1.
AP-4500B was added and hydrolysis was carried out for 24 hours. Add 0.5 g of activated carbon (Shirasagi) to the hydrolyzed solution and heat at 40℃ for 1
After holding for a period of time, it was filtered.

Thereafter, the mixture was treated with an ultrafiltration membrane UH-05 in the same manner as in Example 2, and 10 ml of a clear colorless sugar solution was obtained from the filtrate. 7 hours of this liquid
After concentrating to 5% and crystallizing by adding 5+ml of methanol, 8.6 g of xylose crystals were obtained. The crystal purity was analyzed by liquid chromatography and found to be 98.8%.

Example 5 Approximately 2cm square in a 250m1 stainless steel pressure container.

30 g of white birch chips with a thickness of 3 to 4 fi were introduced, steam was introduced, the temperature was maintained at 200° C. for 5 minutes, and then rapidly discharged to the outside. The released product was extracted with 450 ml of hot water to obtain 405 g of sugar solution A-4.

Next, 800 grams of cellulase TAP-4 was added to the sugar solution A-4, the pH was adjusted to 4.5, and partial hydrolysis was performed at 45° C. for 3 hours to obtain Il solution B-4.

Next, 310 g of sugar solution C-4 was obtained by passing through an ultrafiltration membrane IJH-05 having a molecular weight cut off of 500.

0.3 g of activated carbon was added to this sugar solution C-4, stirred at 40°C for 1 hour, filtered, and the filtrate was passed through an IQ mL cation exchange resin and then through a 10 Ill anion exchange resin until the concentration reached 70%. When concentrated, 6.1g of colorless and transparent sugar solution D-
I got 4.

Table 4 shows the analysis results of sugar solutions A-4, B-4, C-4 and D-4.

(Margin below)

Claims (1)

[Claims] 1 Plant raw materials containing xylan are heated with hot water or saturated steam.
A xylose and Method for producing oligosaccharides.