KR101246078B1 - Extraction method of water soluble, low molecular weight dietary fiber from lignocellulosic biomass - Google Patents

Abstract

The lignocellulosic biomass is suspended in water prepared in advance so that the pH of the extract is 3.8 to 4.5 after extraction of the water-soluble dietary fiber, followed by hydrothermal extraction at 140 to 170 ° C. for 10 minutes to 5 hours, and rapidly to room temperature. The water-soluble dietary fiber extraction method from the lignocellulosic biomass of the present invention comprising the step of cooling, wherein the low molecular weight water-soluble water containing a small amount of monosaccharides and lignin decomposition products while containing a large amount of two or more xyloligosaccharides and the like The dietary fiber can be extracted in high yield, and it is also advantageous for subsequent purification and concentration to obtain a good water-soluble dietary fiber at low cost.

Description

Extraction method of low molecular weight water soluble dietary fiber from lignocellulosic biomass {EXTRACTION METHOD OF WATER SOLUBLE, LOW MOLECULAR WEIGHT DIETARY FIBER FROM LIGNOCELLULOSIC BIOMASS}

The present invention relates to a method for extracting low molecular weight water-soluble fiber from a lignocellulosic biomass in high yield.

Dietary fiber is a generic term for fibrous substances that cannot be digested by human enzymes, and is composed mostly of non-starchy substances made by plants. The most important dietary fiber is cellulose, hemicellulose, lignin, pectin and gum. This dietary fiber is mainly used as a functional material in the food industry, such as dessert products such as jelly, favorite foods such as candy, supplements such as jams, beverages, dairy products, and formal dairy products. Recently, the demand for functional cosmetics, dietary supplements and pharmaceutical precursors is increasing rapidly.

Dietary fiber is classified into water-soluble dietary fiber and water-insoluble dietary fiber according to the degree of dissolving in water. Water-soluble dietary fiber, for example, is a relatively small molecular weight, water-soluble oligosaccharide, and is widely used in the production of functional drinks and formal preparations.

At present, the main raw material of dietary fiber is grains such as wheat, and onion, banana and ginger are used as side materials. Alkaline extraction method (Anna Ebringerova et al., 2000) using caustic soda has been mainly used as a method of extracting dietary fiber from raw materials, and a method of increasing extraction efficiency by adding hydrogen peroxide to it has been reported.

However, the dietary fiber obtained by these techniques is a polymer having high degree of polymerization of sugars, but it is hard to dissolve in water because strong side chains remove most of side chains such as acetyl group and various uronic acids. Will be manifested. Therefore, in order to prepare low molecular weight water-soluble oligosaccharides, it is necessary to perform selective hydrolysis using an enzyme, and thus it is not useful for the preparation of water-soluble dietary fiber.

Recently, many attempts have been made to apply hot water extraction technology to the production of water soluble fiber. The water-soluble dietary fiber obtained mainly at this time is a hydrolyzate of hemicellulose, which is one of the most abundant components in lignocellulosic biomass, and chemically, xylose, in which beta bonds of pentose sugars such as xylose and arabinose are beta-bonded. Oligosaccharides are the most abundant. In addition, the oligosaccharide contains side chains such as the above-described acetyl group and various uronylic acids, and lignin components such as ferulic acid, which are known to exhibit various physiological activities.

In addition, hemicellulose hydrolyzate extracted by hot water extraction is a large part of xyloligosaccharides having a small molecular weight, and contains a large amount of monosaccharides such as xylose which cannot function as dietary fiber. In detail, when the temperature of hot water extraction is typically 140 ° C. or less, non-dietary fibers such as starch are mainly extracted, and dietary fibers such as xyloligosaccharides are hardly dissolved. However, as the extraction temperature increases, the hydrolysis of hemicellulose in the biomass is promoted, and further hydrolysis to monosaccharides increases, so that the yield of oligosaccharides decreases rapidly. This is because water is acidified at high temperature, and various acids such as acetic acid attached to the hemicellulose side chain of the biomass are released to accelerate the acidity, thereby further accelerating the hydrolysis by the acid catalyst.

Accordingly, the present inventors have solved the above problems, and after diligently examining a method for extracting a low molecular weight water soluble dietary fiber using lignocellulosic biomass, the extract is extracted after hot water extraction of biomass within a specific temperature range. The present invention was found to be able to suppress the production of monosaccharides such as xylose, and to obtain a relatively high yield of oligosaccharides by adding a base to the biomass suspension before hot water extraction if necessary so that the acidity is within a certain range. It was completed.

Accordingly, it is an object of the present invention to provide a method for extracting low molecular weight water soluble dietary fiber in high yield from lignocellulosic biomass.

In accordance with the above object, the present invention is a lignocellulosic biomass, suspended in the extraction solvent so that the pH of the extract after extraction of water-soluble dietary fiber to 3.8 to 4.5 and extracted with hot water for 10 minutes to 5 hours at 140 to 170 ℃ It provides a method for extracting the water-soluble dietary fiber from lignocellulosic biomass, comprising the step of rapid cooling to.

According to the method for extracting a water-soluble dietary fiber from lignocellulosic biomass of the present invention, a low-molecular-weight water-soluble fiber containing a small amount of monosaccharides and lignin decomposition products and a large amount of xyloligosaccharides and the like of disaccharides or more can be extracted in high yield. This may be advantageous for subsequent purification and concentration to yield a good water soluble dietary fiber at low cost.

Hereinafter, the present invention will be described in more detail.

As used herein, the term "lignocellulose-based biomass" refers to terrestrial plants that mainly contain cellulose, hemicellulose and lignin as constituents of biomass, and examples thereof include corn stalks, sunflower stalks, rice straw, straw, barley. Herbals such as straw and oil palm trees; And woody trees such as lily, willow and spruce.

As used herein, the term "hydromass extraction of biomass" refers to an operation of extracting at a temperature higher than normal temperature after adding water to the pulverized biomass, and specifically, except for the water-soluble dietary fiber to be obtained in the present invention. Extraction pretreatment process that extracts biomass powder into boiling water below 120 ℃ to remove components that can be extracted in boiling water, and biomass that has already been extracted from boiling water to extract water-soluble dietary fiber. Both the step of adding water or a low aqueous alkali solution to the extraction to extract at 140 to 170 ℃.

As used herein, the term "low molecular weight water soluble dietary fiber" refers to a polysaccharide composed of two or more molecules of xylose or the like produced by hydrolysis of hemicellulose, which is one of the main components of lignocellulosic biomass, and bio Depending on the type of mass, hexose such as glucose, arabinose, galactose and mannose and octane sugar may be connected in a side chain, and acetyl group, uronil group, and ferulic acid may be connected. May be combined.

In addition, the term "acid hydrolysis" as used herein refers to the addition of sulfuric acid to dietary fiber extracts for analysis by high-performance liquid chromatography (HPLC) by making xyloligosaccharides in the extract into xylose form and chemically hydrolyzing at high temperatures. Decomposition is an operation that is not related to dietary fiber extraction.

The present invention is carried out at a high temperature that can promote the hydrolysis of hemicellulose during extraction of low molecular weight water-soluble dietary fiber from lignocellulosic biomass, while the acidity of the extract within a certain range to suppress the phenomenon of further hydrolysis into monosaccharides. By maintaining and extracting hot water, a water-soluble dietary fiber consisting of two or more molecules of sugar is obtained in high yield.

More specifically, the method for extracting the water-soluble dietary fiber from the lignocellulosic biomass according to the present invention is suspended by extracting the lignocellulosic biomass in the extraction solvent so that the pH of the extract is 3.8 to 4.5 after extraction of the water-soluble dietary fiber. After the hot water extraction for 10 minutes to 5 hours at 170 ℃ to include a rapid cooling to room temperature.

In the present invention, the lignocellulosic biomass, which is a raw material of the water-soluble dietary fiber, is a land plant composed of cellulose, hemicellulose, and lignin, and includes both herbaceous and woody plants. Examples of the herbal biomass that can be used as a raw material in the present invention include, but are not particularly limited to, corn stalks, sunflower stalks, rice straws, straws, barley straws, oil palm trees, etc., which are obtained as agricultural by-products. Examples of the mass include lily, willow, and spruce. In addition, silver grass and reeds, which have recently attracted much attention as energy crops, are also included in lignocellulosic biomass to which the hot water extraction technology of the water-soluble dietary fiber of the present invention can be applied.

Such biomass may be used in the form of a conventionally processed for bioenergy production or biorefinery process, that is, in a crushed or pulverized state, and finely ground in order to increase extraction efficiency and suppress generation of impurities. Do.

In addition, in order to remove non-structural components such as starch, which can be extracted together as impurities in the hydrothermal extraction process of water-soluble dietary fiber from biomass, the bio-extracted biomass was first extracted with water of 120 ° C. or lower. The use of the mass pretreatment as the biomass raw material of the present invention may be a more preferable raw material within a range that does not significantly affect the extraction efficiency of the water-soluble dietary fiber according to the present invention.

Subsequently, the biomass prepared by the above method is suspended in the extraction solvent so that the pH of the extract is 3.8 to 4.5 after extraction of the water-soluble dietary fiber, and then heated at the same time with stirring in a sealed state to reach 140 to 170 ° C. The hydrothermal extraction process is carried out while maintaining for 10 minutes to 5 hours.

Water may be used as the extraction solvent, and in order to increase the extraction efficiency, before suspending the lignocellulosic biomass in the extraction solvent, a base is added to the water so that the pH of the extract is 3.8 to 4.5 and then the extraction solvent. Can also be used as

Specifically, the hot water extraction method of the water-soluble dietary fiber of the present invention at the extraction temperature of 140 to 170 ℃, preferably 150 to 160 ℃, the acidity of the extract after the hot water extraction, that is, oligosaccharides of at least two molecules when the pH is 3.8 to 4.5 This can be obtained in maximum yield. Therefore, it is more preferable to measure the acidity of the extract after extraction of the dietary fiber in the preliminary experiment, and to suspend the biomass in water in which the base is dissolved in an amount capable of making this pH 3.8 to 4.5. At this time, the base that can be used is sodium hydroxide (sodium hydroxide), potassium hydroxide (potassium hydroxide) and calcium hydroxide (calcium hydroxide), and the like, especially if the base that can maintain the acidity of the extract within 3.8 to 4.5 after hot water extraction There is no limitation on the type and amount added. If the acidity of the hot water extract is less than 3.8, the extraction rate of hemicellulose increases with the increase of monosaccharides, and consequently, the yield of dietary fiber decreases. As a result, the extraction rate of dietary fiber is reduced, which is not preferable.

In addition, in the hot water extraction method of the water-soluble dietary fiber of the present invention, it is important to maintain the hot water extraction temperature of the biomass suspension at 140 to 170 ° C. for a predetermined time. When the hot water extraction temperature is less than 140 ℃, the concentration of monosaccharides produced by the hydrolysis of hemicellulose decreases, but the yield of water-soluble dietary fiber is further reduced, which is undesirable. In contrast, when the hot water extraction temperature exceeds 170 ℃, hydrolysis of hemicellulose It is not desirable because the rate increases but at the same time the production of monosaccharides also increases rapidly, which reduces the yield of soluble fiber. Therefore, it is preferable that the hot water extraction temperature does not deviate from this range, and in order to extract the dietary fiber which consists of low molecular weight oligosaccharide with the maximum yield, it is more preferable to maintain the hot water extraction temperature at 150-160 degreeC. In addition, the hot water extraction temperature is most preferable because it can maximize the extraction rate and extraction rate when maintained at 160 ℃.

In addition, the hot water extraction method of the water-soluble dietary fiber of the present invention, in addition to the acidity and hot water extraction temperature of the extract is preferably maintained for 10 minutes to 5 hours. Within the time range, the closer the acidity of the hot water extract is to 3.8 and the closer the hot water extraction temperature is to 170 ° C., the shorter the extraction time. On the contrary, the closer the acidity is to 4.5 and the closer the hot water extraction temperature is to 140 ° C., the extraction time. It is more preferable to keep the length of time.

Optimum conditions for hot water extraction of the water-soluble dietary fiber of the present invention may vary slightly depending on the type of biomass to extract the dietary fiber, when using the straw as biomass when the pH of the extract extracted at 160 ℃ is about 3.9 The best extraction rate can be obtained, and when barley straw is used as biomass, the best extraction rate can be obtained when the pH of the extract extracted at 160 ° C. is about 4.1.

In addition, when extracting the water-soluble dietary fiber from lignocellulosic biomass using the hot water extraction method of the present invention, if the acidity of the extract is maintained at pH 3.8 to 4.5 by the characteristics of the biomass, without adding a base By controlling the temperature, low molecular weight dietary fiber can be extracted at maximum yield. Therefore, the addition of a base to water as an extraction solvent in the hot water extraction method of the present invention is not a requirement, it can be said that the most important requirement is to adjust the final pH of the extract to be maintained at 3.8 to 4.5.

In the present invention, when the biomass powder is suspended in water to extract the water-soluble dietary fiber from the biomass, the mixing ratio of biomass and water is a ratio which can be seen in the pretreatment of biomass which is common in the bioenergy industry or the biorefinery industry. For example, the ratio of biomass and water or aqueous base solution may be used from 1:99 to 20:80. For precise control of the hot water extraction temperature and uniform mixing of the reactants, the ratio is preferably 1:99 to 15:85, more preferably 1:99 to 10:90.

Subsequently, by rapidly cooling the extract to room temperature, a low molecular weight water soluble dietary fiber can be extracted from the lignocellulosic biomass. Since a cooling process can be performed according to a conventional method, detailed description is abbreviate | omitted in this specification.

As described above, before suspending the lignocellulosic biomass in the extraction solvent so that the acidity of the dietary fiber extract obtained by the hot water extraction process is within a certain range, pretreatment such as adding a base to the extraction solvent water in advance By adjusting the acidity, and then extracting hot water within a predetermined temperature range for a predetermined time, the hydrolysis of hemicellulose is hydrolyzed into oligosaccharides from the biomass, while increasing the rate of extraction and adding additional hydrolyzed monosaccharides such as xylose. By suppressing the phenomenon of degradation, the obtained extract contains less monosaccharides and lignin degradation products, but contains more than two saccharides such as xyloligosaccharides. As a result, it is possible to maximize the yield of low molecular weight water-soluble dietary fiber.

Hereinafter, the present invention will be described in more detail with reference to Examples. However, the following examples are only examples of the present invention and the present invention is not necessarily limited thereto.

Manufacturing example : Lignocellulosic From biomass Extractable  Preparation of Samples with Components Removed

Immediately after harvesting edible corn (University Chaksu, Chungbuk National University), rice (chuchu rice), edible barley and Korean wheat, the stems were cut and dried in the sun, and then pulverized to a powder of 20 mesh or less (hereinafter referred to as 'wind dry sample'). ). The air dried sample was placed in a high temperature dryer at 105 ° C., dried for 48 hours, and weighed to measure moisture content. The dry weight of the air dried sample was placed in a bag made of cotton fiber, and then put into a steamer containing 20 liters of water and boiled for 1 hour. The bag was taken out, pressed and squeezed in a hot state, and the dried ingredients were placed in 10 liters of distilled water, and then squeezed five times to remove the extractable components. After removing the extractable ingredient in a shade, dried, and then crushed lightly, stored in an airtight container was used as a sample (hereinafter referred to as 'extractable ingredient removal sample') for hot water extraction of the water-soluble dietary fiber.

Example  1-1 to 1-4: From barley straw  Of water soluble fiber Hydrothermal extraction

Four pressure vessels (for 15 ml, manufactured by Chemglass, USA) were added 10 ml of distilled water each. Here, the extract of the extractable barley straw sample obtained in the preparation example was put in an amount corresponding to 1 g in the air dried sample building. The pressure vessel was sealed with a stopper and then placed in an oil bath at 145, 150, 155 and 160 ° C and extracted. The samples were taken from the oil bath at regular time intervals from 30 minutes to 5 hours after hot water extraction, cooled in cold water, and mixed well.

Example  2-1 to 2-4: from water-soluble dietary fiber Hydrothermal extraction

10 ml of distilled water were put into four pressure vessels (for 15 ml, manufactured by Chemglass, USA). Herein, the extractable straw sample obtained in the preparation example was placed in an amount corresponding to 1 g in the air dried sample building. The pressure vessel was sealed with a stopper and then placed in an oil bath at 145, 150, 155 and 160 ℃ and extracted. The samples were taken from the oil bath at regular time intervals from 30 minutes to 5 hours after hot water extraction, cooled in cold water, and mixed well.

Example  3: From barley straw  Of water soluble fiber Hydrothermal extraction

10 ml of distilled water was added to a pressure-resistant container (for 15 ml, manufactured by Chemglass, USA), and dissolved by adding 0.0022 g of sodium hydroxide to the extractable barley straw sample obtained in the above preparation. 1 g equivalent. The pressure vessel was sealed with a stopper and then placed in an oil bath at 160 ° C and extracted. After 3 hours of hot water extraction, it was taken out of the oil bath, cooled in cold water, and mixed well.

Example  4: from straw to soluble fiber Hydrothermal extraction

10 ml of distilled water was added to a pressure-resistant container (for 15 ml, manufactured by Chemglass, USA), and 0.0016 g of sodium hydroxide was dissolved therein, followed by dissolving the extractable straw extract sample obtained in the above example in an air-dry sample building. Put into. The pressure vessel was sealed with a stopper and then placed in an oil bath at 160 ° C and extracted. After 3 hours of hot water extraction, it was taken out of the oil bath, cooled in cold water, and mixed well.

Example  5-1: Soluble Dietary Fiber from Corn Stalk Hydrothermal extraction

10 ml of distilled water was placed in a pressure-resistant container (for 15 ml, manufactured by Chemglass, USA), and the extractable component-removed corn stalk samples obtained in the preparation example were put in an amount corresponding to 1 g in a dry building. The pressure vessel was sealed with a stopper and then extracted into an oil bath at 160 ℃. After 5 hours of hot water extraction, it was taken out of the oil bath, cooled in cold water, and mixed well.

Example  5-2: Soluble Dietary Fiber from Corn Stalk Hydrothermal extraction

10 ml of distilled water was added to a pressure-resistant container (for 15 ml, manufactured by Chemglass, USA), and 0.0112 g of sodium hydroxide was dissolved therein, followed by dissolving the extractable component-removed corn stalk sample obtained in the above preparation in an air-drying sample. Put into. The pressure vessel was sealed with a stopper and then extracted into an oil bath at 160 ℃. After 5 hours of hot water extraction, it was taken out of the oil bath, cooled in cold water, and mixed well.

Example  5-3: Soluble Dietary Fiber from Corn Stalk Hydrothermal extraction

10 ml of distilled water was added to a pressure-resistant container (for 15 ml, manufactured by Chemglass, USA), and dissolved by adding 0.0028 g of sodium hydroxide thereto. Put into. The pressure vessel was sealed with a stopper and then extracted into an oil bath at 160 ℃. After 3 hours of hot water extraction, it was taken out of the oil bath, cooled in cold water, and mixed well.

Example  6-1: Soluble Dietary Fiber from Rice Straw Hydrothermal extraction

10 ml of distilled water was added to a pressure-resistant container (for 15 ml, manufactured by Chemglass, USA), and 0.0058 g of sodium hydroxide was dissolved therein to dissolve the extractable rice straw sample obtained in the above preparation in an amount equivalent to 1 g in a dry building. Put in. The pressure vessel was sealed with a stopper and then extracted into an oil bath at 160 ℃. After 5 hours of hot water extraction, it was taken out of the oil bath, cooled in cold water, and mixed well.

Example  6-2: Soluble Dietary Fiber from Rice Straw Hydrothermal extraction

10 ml of distilled water was added to a pressure-resistant container (for 15 ml, manufactured by Chemglass, USA), and dissolved by adding 0.0029 g of sodium hydroxide thereto. Put in. The pressure vessel was sealed with a stopper and then extracted into an oil bath at 160 ℃. After 3 hours of hot water extraction, it was taken out of the oil bath, cooled in cold water, and mixed well.

Comparative example  1: Soluble Diet of Fiber from Corn Stalk at High Acidity Hydrothermal extraction

10 ml of distilled water was put into a pressure-resistant container (for 15 ml, manufactured by Chemglass, USA), and 0.0224 g of sodium hydroxide was added thereto to dissolve it. Put into. The pressure vessel was sealed with a stopper and then extracted into an oil bath at 160 ℃. After 5 hours of hot water extraction, it was taken out of the oil bath, cooled in cold water, and mixed well.

Comparative example  2: from water-soluble dietary fiber Hydrothermal extraction

10 ml of distilled water was placed in a pressure-resistant container (for 15 ml, manufactured by Chemglass, USA), and the extractable straw-removing rice straw sample obtained in the preparation example was put in an amount corresponding to 1 g in a dry building. The pressure vessel was sealed with a stopper and then extracted into an oil bath at 160 ℃. After 5 hours of hot water extraction, it was taken out of the oil bath, cooled in cold water, and mixed well.

Comparative example  3: soluble fiber from rice straw at high acidity Hydrothermal extraction

10 ml of distilled water was added to a pressure-resistant container (for 15 ml, manufactured by Chemglass, USA), and 0.023 g of sodium hydroxide was dissolved therein to dissolve the sample. Put in. The pressure vessel was sealed with a stopper and then extracted into an oil bath at 160 ℃. After 5 hours of hot water extraction, it was taken out of the oil bath, cooled in cold water, and mixed well.

Test Example  1: water soluble fiber Of hot-water extract pH  Measure

A pH meter electrode was added to the dietary fiber extract in the pressure-resistant container obtained in Examples and Comparative Examples to measure the acidity at room temperature of the hydrothermal extract, and the average value was obtained. The results are shown in Tables 1 to 3 below.

Test Example  2: Biomass Hot water extract  Of Non-dietary fiber  As an ingredient Xylose  Concentration measurement

The extracts obtained in the examples and comparative examples were transferred to 50 ml Falcon tubes, respectively, and the wash solution in which the residue in the pressure vessel was washed with distilled water was also added to each Falcon tube. Distilled water was added to make the contents weigh 40 g, and then a part of this was diluted with distilled water to prepare a 1,000-fold dilution solution, and xylose was prepared by ion chromatography (DIONEX model IC-5000, USA). Quantification As a result, the average value is shown in Tables 1-3.

Test Example  3: Biomass Hot water extract  As a dietary fiber Xyloligosaccharide  Content measurement

In order to measure the concentration of xyloligosaccharides in the hot water extract, a sulfuric acid solution was added to each of the extracts obtained in Examples and Comparative Examples according to the Laboratory Analytical Procedure of the National Renewable Energy Laboratory (NREL). Acid hydrolysis. After taking a part of it and diluting 1,000 times, xylose was quantified by ion chromatograph (DIONEX model IC-5000, USA). From the quantified results, the amount of xylose as monosaccharide of Test Example 2 was subtracted to calculate the amount of xylose as xyloligosaccharide, and the average values are shown in Tables 1 to 3 as a result.

Test Example  4: Biomass Hot water extract  medium Trisaccharide  ideal Xyloligosaccharide  Average molecular weight measurement

A portion of each of the extracts obtained in Examples and Comparative Examples was taken and analyzed by gel permeation chromatography (GPC), and the average molecular weight of oligosaccharides of at least three sugars was found to be perfect for separation of peaks on the analyzed chromatogram. Calculated. As a result, the average value is shown in Tables 1-3.

Example Biomass water
(ml) Hydroxide
salt
Addition amount
(g) extraction
Temperature
( ^o C) extraction
time
(time) PH after extraction extract
medium
Xylose
(g) Xylose After Extract Hydrolysis
(g) Xylose as Xyloligosaccharide
(g) Average molecular weight of more than 3 sugars 1-1 Barley straw 10 0 145 5 4.44 0.20 4.7 4.5 6,552 1-2 10 0 150 5 4.22 0.40 6.5 6.1 4,112 1-3 10 0 155 4 4.04 1.0 8.7 7.7 2,137 1-4 10 0 160 3 4.02 1.3 10.0 8.7 1,817

As shown in Table 1, the amount of water-soluble dietary fiber extracted from barley straw increases as the temperature approaches 160 ° C and the acidity of the extract approaches pH 4, and the average molecular weight of the extract decreases gradually, thereby lowering the molecular weight of the present invention. It can be seen that it is advantageous for the production of water-soluble dietary fiber.

Example Biomass water
(ml) Hydroxide
salt
Addition amount
(g) extraction
Temperature
( ^o C) extraction
time
(time) PH after extraction extract
medium
Xylose
(g) Xylose After Extract Hydrolysis
(g) Xylose as Xyloligosaccharide
(g) Average molecular weight of more than 3 sugars 2-1 straw 10 0 145 5 3.92 0.44 8.0 7.6 3,515 2-2 10 0 150 4 3.81 0.64 9.5 8.9 2,842 2-3 10 0 155 3 3.89 1.1 7.2 6.1 2,039 2-4 10 0 160 2 3.85 1.0 8.1 7.1 2,134

As shown in Table 2, the amount of water-soluble dietary fiber obtained from straw was the highest in the vicinity of acidity of 3.8, and it was found that 150 ° C., which had a slightly lower hot water extraction temperature, was advantageous.

Biomass water
(ml) Hydroxide
salt
Addition amount
(g) extraction
Temperature
( ^o C) extraction
time
(time) PH after extraction extract
medium
Xylose
(g) Xylose After Extract Hydrolysis
(g) Xylose as Xyloligosaccharide
(g) Average molecular weight of more than 3 sugars Comparative Example 1 Corn stalk 10 0.0224 160 5 4.81 0.08 4.4 4.3 Unmeasured Example 5-1 10 0 160 5 3.83 1.9 6.5 4.6 Unmeasured Example 5-3 10 0.0028 160 3 4.06 0.84 8.8 8.0 Unmeasured Comparative Example 2 Straw 10 0 160 5 3.68 3.9 7.9 4.0 Unmeasured Comparative Example 3 10 0.023 160 5 5.07 0.048 4.1 4.1 Unmeasured Example 6-2 10 0.0029 160 3 4.04 0.58 8.0 7.4 Unmeasured Example 1-4 Barley straw 10 0 160 3 4.02 1.3 10 8.7 1,817 Example 3 10 0.0022 160 3 4.18 0.93 8.6 7.7 1,826 Example 2-2 straw 10 0 150 4 3.81 0.64 9.5 8.9 2,842 Example 4 10 0.0016 160 3 3.91 1.8 11.1 9.3 1,406

As shown in Table 3, in the extraction test in which sodium hydroxide was added to the biomass suspension to maintain the acidity of the hot water extract near pH 4.0, both corn stalks and rice straws were able to obtain low molecular weight water-soluble fiber. . In addition, in a straw-based test, the acidity of the extract was slightly suppressed by adding a small amount of sodium hydroxide to the biomass suspension, thereby obtaining a dietary fiber having a lower molecular weight.

On the other hand, the yield of xyloligosaccharides in the rice straw extract according to Example 6-2 was higher than 92%, wherein the pH of the extract was 4.04, whereas the pH of the extract after dietary fiber extraction was outside the limited range in the present invention. In the case of Comparative Example 2 which is 3.68, the content of xylose in the extract is high, and thus, the yield (about 51%) of xyloligosaccharide in the extract obtained is significantly lower than that in Example 6-2. When extracting water-soluble dietary fiber from lignocellulosic biomass from these results, it is possible to reduce the production rate of xylose, a monosaccharide, and to extract the xyloligosaccharide as the dietary fiber composed of two or more xylose molecules in the best yield. In order to extract the dietary fiber, the pH of the extract is 3.8 to 4.5, it can be seen that the hot water extraction is carried out for 10 minutes to 5 hours at a temperature of 140 to 170 ℃.

Analytical values of the water-soluble dietary fiber presented in the test example of the present invention shows only the quantitative results of xylose as one component constituting the fiber. In fact, arabinos, galactose, mannose, glucose, acetyl groups and various euronyl groups are attached to them, so this is a measure of convenience rather than actual dietary fiber weight.

In the above, the present invention has been described with reference to the above embodiments, which are only examples, and the present invention will be described below in various modifications and equivalents which are obvious to those skilled in the art. It should be understood that it can be carried out within the scope of the appended claims.

Claims (4)

The lignocellulosic biomass is suspended in an extraction solvent so that the pH of the extract is 3.8 to 4.5 after extraction of the water-soluble dietary fiber, followed by rapid cooling to room temperature after hot water extraction at 140 to 170 ° C. for 10 minutes to 5 hours. And water-soluble dietary fiber extraction method from lignocellulosic biomass. The method of claim 1,
Before suspending the lignocellulosic biomass in an extraction solvent, the method further comprises adding a base to the extraction solvent in an amount such that the pH of the extract becomes 3.8 to 4.5 after extraction of the water-soluble dietary fiber. Water-soluble dietary fiber extraction method from lignocellulosic biomass. The method of claim 1,
The hot water extraction is characterized in that carried out for 10 minutes to 5 hours at 150 to 160 ℃, water-soluble dietary fiber extraction method from lignocellulosic biomass. The method of claim 1,
The lignocellulosic biomass is selected from herbaceous and wood based biomass, water-soluble dietary fiber extraction method from lignocellulosic biomass.