Carbohydrate composition derived from broad-leaved trees

Abstract

Disclosed is a hardwood-derived carbohydrate composition containing monomeric sugars in an amount of 65 to 85% by weight based on the total dry matter content of the carbohydrate composition. The monomeric sugars include monomeric xylose, and the amount of monomeric xylose in the carbohydrate composition is 50 to 70% by weight based on the total dry matter content of the carbohydrate composition, a hardwood-derived carbohydrate composition. The carbonyl content of the carbohydrate composition is 5000 to 20000 μg / g based on the total dry matter content of the carbohydrate composition. Further disclosed are a method for producing the hardwood-derived carbohydrate composition and its use.

Description

Technical Field

[0001] The present disclosure relates to a hardwood-derived carbohydrate composition containing monomeric sugars. Further, the present disclosure relates to a method for producing this hardwood-derived carbohydrate composition. Further, the present disclosure relates to the use of this hardwood-derived carbohydrate composition.

Background Art

[0002] Various methods are known for converting bio-based raw materials such as lignocellulosic biomass into liquid streams of various sugars. It still remains a challenge for researchers to be able to provide a sufficiently pure carbohydrate composition having properties suitable for further uses, such as the production of glycol, ethanol, or xylitol.

Summary of the Invention

Means for Solving the Problems

[0003] A hardwood-derived carbohydrate composition is disclosed. This hardwood-derived carbohydrate composition contains monomeric sugars in an amount of 65 to 85% by weight based on the total dry matter content of the carbohydrate composition, and this monomeric sugar contains monomeric xylose. The amount of monomeric xylose in this carbohydrate composition is 50 to 70% by weight based on the total dry matter content of the carbohydrate composition. The carbonyl content of the carbohydrate composition is 5000 to 20000 μg / g based on the total dry matter content of the carbohydrate composition.

[0004] Furthermore, a method for producing a hardwood-derived carbohydrate composition as defined in the present application is disclosed, and this method includes i) providing a feedstock of hardwood-derived carbohydrates in the form of a liquid fraction having a total dry matter content of 5 to 30% by weight; ii) subjecting the feedstock of the hardwood-derived carbohydrates to treatment using granular activated carbon; iii) A step of collecting the feedstock of the hardwood-derived carbohydrate subjected to granular activated carbon treatment, wherein the collection of the feedstock is continued until the absorbance of the collected feedstock becomes at most 70% of the maximum absorbance of the provided feedstock of the hardwood-derived carbohydrate. iv) A step of adjusting the pH of the collected feedstock of the hardwood-derived carbohydrate to a pH value of 2.2 to 3.0. v) A step of subjecting the feedstock having a pH value of 2.2 to 3.0 to evaporation until the total dry matter content of the feedstock becomes 30 to 80% by weight. including, and producing the hardwood-derived carbohydrate composition.

[0005] Furthermore, the use of the hardwood-derived carbohydrate composition disclosed herein in a fermentation process for the production of a sweetener or for the production of biogas is disclosed. Furthermore, the use of the method is disclosed.

Mode for Carrying Out the Invention

[0006] A hardwood-derived carbohydrate composition is disclosed. This hardwood-derived carbohydrate composition contains monomeric sugars in an amount of 65 to 85% by weight based on the total dry matter content of the carbohydrate composition, and this monomeric sugar contains monomeric xylose. The amount of monomeric xylose in this carbohydrate composition is 50 to 70% by weight based on the total dry matter content of the carbohydrate composition. The carbonyl content of this carbohydrate composition is 5000 to 20000 μg / g based on the total dry matter content of the carbohydrate composition.

[0007] The hardwood-derived carbohydrate composition may be in a liquid or liquid form. The method disclosed herein may produce a hardwood-derived carbohydrate composition in a liquid form.

[0008] Furthermore, a method for producing a hardwood-derived carbohydrate composition as defined in the present application is disclosed, and this method includes: i) A step of providing a feedstock of hardwood-derived carbohydrate in the form of a liquid fraction having a total dry matter content of 5 to 30% by weight. ii) subjecting the raw material for supplying the hardwood-derived carbohydrate to a treatment using granular activated carbon; iii) a step of collecting the raw material for supplying the hardwood-derived carbohydrate that has been subjected to the granular activated carbon treatment, wherein the collection of the raw material for supply is continued until the absorbance of the collected raw material for supply reaches at most 70% of the maximum absorbance of the raw material for supplying the hardwood-derived carbohydrate provided; iv) a step of adjusting the pH of the collected raw material for supplying the hardwood-derived carbohydrate to a pH value of 2.2 to 3.0; v) subjecting the raw material for supply having a pH value of 2.2 to 3.0 to evaporation until the total dry matter content of the raw material for supply becomes 30 to 80% by weight; and producing the hardwood-derived carbohydrate composition.

[0009] In one embodiment, steps i), ii), iii), iv), and v) are sequentially performed in this order. In one embodiment, steps i), ii), iii), iv), and v) are sequentially performed in this order, and no additional steps are performed therebetween.

[0010] Absorbance is measured at a wavelength of 420 nm using a spectrophotometer by using a 1 cm cuvette. The absorbance of the provided hardwood-derived carbohydrate feedstock is measured before the step of subjecting the hardwood-derived carbohydrate feedstock to treatment with granular activated carbon. Further, the absorbance of the collected feedstock is measured and the measured absorbances are compared. The collection of the hardwood-derived carbohydrate feedstock subjected to granular activated carbon treatment is continued until the absorbance of the collected feedstock is at most 70% of the absorbance of the provided hardwood-derived carbohydrate feedstock. That is, the absorbance of the feedstock may be tracked during collection. Subjecting the hardwood-derived carbohydrate feedstock to treatment with granular activated carbon may be performed as a batch process. In one embodiment, the collection of the hardwood-derived carbohydrate feedstock subjected to granular activated carbon treatment is continued until the absorbance of the collected feedstock is at most 66%, or at most 60%, or at most 50%, or at most 40% of the absorbance of the provided hardwood-derived carbohydrate feedstock. In one embodiment, the collection of the hardwood-derived carbohydrate feedstock subjected to granular activated carbon treatment is continued until the absorbance of the collected feedstock is 20 - 70%, or 30 - 66%, or 35 - 60%, or 40 - 50% of the absorbance of the provided hardwood-derived carbohydrate feedstock.

[0011] Further, the use of the hardwood-derived carbohydrate composition disclosed herein in a fermentation process for the production of a sweetener or for the production of biogas is disclosed. This fermentation process may be, for example, ethanol fermentation. The sweetener may be, for example, xylitol or xylose. In one embodiment, the production of the sweetener includes the crystallization of xylose from the hardwood-derived carbohydrate composition. In one embodiment, the sweetener is xylose in the form of crystals or syrup.

[0012] In one embodiment, the hardwood-derived carbohydrate composition is a sweetener composition. In one embodiment, the method for producing the hardwood-derived carbohydrate composition is a method for producing a sweetener composition.

[0013] Furthermore, the use of the methods disclosed herein for reducing the amount of soluble lignin in a hardwood-derived carbohydrate composition in order to reduce precipitation of lignin during storage and / or transport of the hardwood-derived carbohydrate composition is disclosed.

[0014] Furthermore, hardwood-derived carbohydrate compositions obtainable by the methods disclosed herein are disclosed. In one embodiment, the hardwood-derived carbohydrate composition obtainable by the methods disclosed herein is the hardwood-derived carbohydrate composition disclosed herein. That is, the hardwood-derived carbohydrate composition disclosed herein may be produced by the methods disclosed herein.

[0015] The hardwood-derived carbohydrate composition may be a composition of beech-derived carbohydrates, a composition of oak-derived carbohydrates, a composition of eucalyptus wood-derived carbohydrates, a composition of aspen wood-derived carbohydrates, or the hardwood-derived carbohydrate composition may be a combination thereof, or a combination thereof with other hardwood species. In one embodiment, the hardwood-derived carbohydrate composition is a composition of beech-derived carbohydrates, a composition of oak-derived carbohydrates, a composition of eucalyptus wood-derived carbohydrates, or a composition of aspen wood-derived carbohydrates. In one embodiment, the hardwood-derived carbohydrate composition is a composition of beech-derived carbohydrates.

[0016] The hardwood-derived carbohydrate composition disclosed herein relates to a composition that contains carbohydrates, but may further contain additional components and / or elements disclosed herein, for example. Thus, "hardwood-derived carbohydrate composition" may be considered "hardwood-derived carbohydrate-containing composition" or "hardwood-derived composition containing carbohydrates".

[0017] The amounts of monomeric sugars (monosaccharides), namely monomeric C5 sugars and monomeric C6 sugars, and oligomeric sugars (oligosaccharides), namely oligomeric C5 sugars and oligomeric C6 sugars, may be determined both qualitatively and quantitatively by high performance liquid chromatography (HPLC) by comparison with a standard sample. Examples of analytical methods can be found, for example, in Sluiter, A. et al., "Determination of sugars, byproducts, and degradation products in liquid fraction process samples", Technical Report, National Renewable Energy Laboratory, 2008, and Sluiter, A. et al., "Determination of Structural Carbohydrates and Lignin in Biomass", Technical Report, National Renewable Energy Laboratory, Revised Edition 2012.

[0018] As used herein, any weight percent is given as a percent of the total dry matter content of the carbohydrate composition, unless otherwise specified. Similarly, other weight fractions (such as ppm) may indicate a fraction of the total dry matter content of the carbohydrate composition, unless otherwise specified.

[0019] The expression "C5 sugar" should be understood herein to refer to xylose, arabinose, or any mixture or combination thereof, unless otherwise specified. The expression "C6 sugar" should be understood herein to refer to glucose, galactose, mannose, fructose, or any mixture or combination thereof, unless otherwise specified. The expression that a sugar is "monomeric" should be understood herein to refer to a sugar molecule that exists as a monomer, i.e., a sugar molecule that is not bound or linked to any other sugar molecule, unless otherwise specified.

[0020] In this specification, the amounts of the different components / elements in the hardwood-derived carbohydrate composition are presented as weight percentages based on the total dry matter content of the carbohydrate composition.

[0021] The expression "total dry matter content" may refer to the total amount of solids including soluble solids or dissolved solids. The hardwood-derived carbohydrate composition may not contain suspended solids and may contain only soluble solids.

[0022] In this specification, the term "total dry matter content of the carbohydrate composition" may refer to the weight of the carbohydrate composition determined after removing any solid particles or solid materials from the carbohydrate composition by filtration, for example, and subjecting the filtrate to drying at a temperature of 45 °C for 24 hours. The effectiveness of the drying may be ensured by weighing the sample, drying it for a further 2 hours at the specified temperature, and weighing the sample again. If the measured weights are the same, the drying is complete and the total weight may be recorded.

[0023] As will be apparent to those skilled in the art, the total amount of the different components / elements in the hardwood-derived carbohydrate composition may not exceed 100 weight %. The amounts in weight % of the different components / elements in the hardwood-derived carbohydrate composition may vary within a given range.

[0024] In one embodiment, the amount of monomeric xylose in the carbohydrate composition is 55 to 65 weight % based on the total dry matter content of the carbohydrate composition.

[0025] In one embodiment, the carbonyl content of the carbohydrate composition is 7500 to 17500 μg / g, or 10000 to 15000 μg / g, based on the total dry matter content of the carbohydrate composition. The expression "carbonyl content" may be regarded as the content of carbonyl compounds containing a functional group consisting of a carbon atom double-bonded to an oxygen atom, i.e., C=O. The carbonyl group is common to several classes of organic compounds as part of many larger functional groups. Compounds containing a carbonyl group are often called carbonyl compounds. Examples of compounds containing a carbonyl group in their structure may include aldehydes, ketones, and carboxylic acids. The carbonyl content in the carbohydrate composition may be determined according to Standard ASTM E411-05(2009).

[0026] The hardwood-derived carbohydrate composition has an additional utility of containing only a small amount of carbonyl groups. As a result, for example, when there are fewer carbonyl groups that cause harmful side reactions, the fermentation of the carbohydrate composition proceeds more smoothly.

[0027] In one embodiment, the carbohydrate composition exhibits an ICUMSA color value of 5000 to 40000 IU, or 7500 to 30000 IU, or 10000 to 20000 IU. The ICUMSA color value may be measured using a modified ICUMSA GS1 method without adjusting the pH of the sample to be analyzed and without filtering the sample through a 0.45 μm filter prior to analysis. The measurement is performed at room temperature, and the pH of the carbohydrate composition is 2.2 to 3.

[0028] In one embodiment, the carbohydrate composition contains soluble lignin in an amount of 1.0 to 4.0 wt%, or 1.25 to 3.75 wt%, or 1.5 to 3.5 wt%, based on the total dry matter content of the carbohydrate composition. The presence of soluble lignin in the carbohydrate composition can be evidence that the carbohydrate composition is derived from wood.

[0029] The amount of soluble lignin may be determined as follows by UV-VIS absorption spectroscopy. The amount of soluble lignin present in the carbohydrate composition is determined by diluting a sample of the carbohydrate composition such that its absorbance at 205 nm is between 0.2 and 0.7 AU when compared to a reference sample of pure water, and using a cuvette with a path length of 1 cm. The soluble lignin content of the sample in mg / l units may then be calculated using the following formula.

Equation

[0030] The total dry matter content of the carbohydrate composition derived from the broad-leaved tree may be 8 to 80 wt%, or 15 to 75 wt%, or 20 to 70 wt% when measured after drying at a temperature of 45 °C for 24 hours.

[0031] In one embodiment, the electrical conductivity of a 65% aqueous solution of the carbohydrate composition is 0.3 to 2.0 mS / cm, or 0.4 to 1.5 mS / cm, or 0.5 to 1.0 mS / cm when determined in accordance with SFS-EN 27888 (1994).

[0032] In one embodiment, the carbohydrate composition contains galactose in an amount of 0.25 to 5 wt%, or 0.5 to 4.5 wt%, or 0.75 to 4.0 wt% based on the total dry matter content of the carbohydrate composition. The amount of galactose may be determined by high performance anion exchange chromatography with pulsed amperometric (pulsed current) detection (HPAE-PAD).

[0033] In one embodiment, the carbohydrate composition contains carboxylic acid in a total amount of 5 to 20 wt%, or 5.5 to 18 wt%, or 6 to 16 wt% based on the total dry matter content of the carbohydrate composition.

[0034] In one embodiment, the carbohydrate composition comprises a total amount of monomeric sugars of 67.5 to 82.5% by weight based on the total dry matter content of the carbohydrate composition.

[0035] In one embodiment, the carbohydrate composition comprises a total amount of monomeric sugars and oligomeric sugars of 67.5 to 95% by weight, or 70 to 94% by weight, or 72.5 to 93% by weight based on the total dry matter content of the carbohydrate composition. In one embodiment, the carbohydrate composition comprises an amount of oligomeric sugars of 1 to 15% by weight, or 2 to 10% by weight based on the total dry matter content of the carbohydrate composition. The chromatographic treatment has the additional utility of reducing the amount of oligomeric sugars in the hardwood-derived carbohydrate composition.

[0036] The expression that a sugar is "oligomeric" should be understood herein, unless otherwise specified, to refer to a sugar molecule consisting of two or more monomers bonded or linked to each other.

[0037] The oligomeric C5 sugar may be xylose and / or arabinose. The oligomeric C6 sugar may be glucose, galactose, mannose, fructose and / or rhamnose.

[0038] In one embodiment, the carbohydrate composition comprises an amount of monomeric C6 sugars of 10 to 20% by weight, or 13 to 17% by weight based on the total dry matter content of the carbohydrate composition.

[0039] In one embodiment, the monomeric sugars include monomeric glucose and monomeric xylose, and the weight ratio of monomeric glucose to monomeric xylose is 0.067 to 0.2, or 0.08 to 0.17, or 0.1 to 0.14. The inventors have surprisingly found that a hardwood-derived carbohydrate composition containing a high content of monomeric C5 sugars, particularly a high ratio of monomeric xylose compared to monomeric glucose, can be produced by the method disclosed herein. By the method disclosed herein, C5 sugars may be efficiently recovered as a hardwood-derived carbohydrate composition.

[0040] The carbohydrate composition may contain organic impurities (including soluble lignin) in an amount of 6 to 30% by weight, or 8 to 28% by weight, or 10 to 26% by weight, or 12 to 24% by weight based on the total dry matter content of the carbohydrate composition.

[0041] Examples of organic impurities include organic acids. Non-limiting examples of organic impurities are oxalic acid, citric acid, succinic acid, formic acid, acetic acid, levulinic acid, 2-furoic acid, 5-hydroxymethylfurfural (5-HMF), furfural, glycolaldehyde, glyceraldehyde, and various salts or esters of acetic acid, salts or esters of formic acid, and other salts or esters. The quality and amount of organic impurities in the carbohydrate composition may be determined using, for example, HPLC combined with a suitable detector, infrared (IR) spectroscopy, ultraviolet-visible (UV-VIS) spectroscopy, or nuclear magnetic resonance (NMR) spectroscopy.

[0042] The carbohydrate composition may contain inorganic impurities. The carbohydrate composition may contain inorganic impurities in an amount of 0 to 6% by weight, or 0.1 to 3% by weight, or 0.2 to 2.0% by weight, or 0.3 to 1% by weight based on the total dry matter content of the carbohydrate composition. The inorganic impurities may be, for example, soluble inorganic compounds in the form of various salts. The inorganic impurities may be salts of elements from the group consisting of Al, As, B, Ca, Cd, Cl, Co, Cr, Cu, Fe, K, Mg, Mn, Mo, Na, Ni, P, Pb, S, Se, Si, and Zn. The amount of inorganic impurities in the carbohydrate composition can be analyzed using inductively coupled plasma optical emission spectrometry (ICP-OES) in accordance with standard SFS-EN ISO11885:2009. Alternatively, ion chromatography (IC) may be used.

[0043] The method for producing the hardwood-derived carbohydrate composition includes a step of providing a feedstock of hardwood-derived carbohydrates in the form of a liquid fraction having a total dry matter content of 5 to 30% by weight. In one embodiment, a feedstock of hardwood-derived carbohydrates in the form of a liquid fraction having a total dry matter content of 6 to 20% by weight, or 7 to 13% by weight is provided.

[0044] In one embodiment, providing a feedstock of hardwood-derived carbohydrates in the form of a liquid fraction includes concentrating the feedstock. The concentration of the feedstock of hardwood-derived carbohydrates may be required to provide a feedstock of hardwood-derived carbohydrates in the form of a liquid fraction having a total dry matter content of 10 to 30 wt%, or 14 to 30 wt%.

[0045] Such a feedstock of hardwood-derived carbohydrates may be provided, for example, as follows.

[0046] First, a wood-based feedstock derived from wood-based raw materials and containing hardwood chips may be provided. Then, this wood-based feedstock may be subjected to a pretreatment to form a slurry, and this pretreatment is a step of subjecting the wood-based feedstock to an impregnation treatment with an impregnating liquid containing sulfuric acid, and this impregnation treatment is carried out at a temperature of 40 to 100 °C for 1 to 30 minutes, a step of subjecting the impregnated wood-based feedstock to a steam explosion treatment to form a steam-treated wood-based feedstock, wherein the amount of sulfuric acid in this steam explosion treatment is 0.10 to 0.75 wt% based on the total dry matter content of the wood-based feedstock, a step of mixing the steam-treated wood-based feedstock with a liquid to form the above slurry, and a step of separating the above slurry by a solid-liquid separation process into a liquid fraction and a fraction containing solid cellulose particles, and recovering this liquid fraction as the feedstock of the hardwood-derived carbohydrates is included.

[0047] The expression "pre-treat (it)" or "pre-treatment" should be understood in this specification, unless otherwise specified, as a process carried out to convert a wood-based feedstock into a slurry that may be separated into a liquid fraction and a fraction containing solid cellulose particles. That is, this liquid fraction may be separated from the fraction containing solid cellulose particles. The fraction containing solid cellulose particles may further contain a certain amount of lignocellulose particles and free-form lignin particles. Lignocellulose contains lignin chemically bonded to cellulose particles.

[0048] The wood-based raw material may be derived from, for example, beech, oak, eucalyptus, ash (Fraxinus), oak, maple (Acer), poplar (Populus), willow, aspen, or poplar. The wood-based raw material may be any combination or mixture of these.

[0049] Generally, wood and wood-based raw materials are essentially composed of cellulose, hemicellulose, lignin, and extractives. Cellulose is a polysaccharide consisting of a chain of glucose units. Hemicellulose contains polysaccharides such as xylan, mannan, and glucan.

[0050] Providing the wood-based feedstock may include subjecting the wood-based raw material to mechanical processing selected from debarking, chipping, splitting, cutting, pulping, grinding, crushing, tearing, sieving, and / or washing the wood-based raw material to form the wood-based feedstock. During this mechanical processing, for example, the bark of a log can be removed, and / or wood chips of a specified size and structure can be formed. The formed wood chips can also be washed, for example, with water to remove, for example, sand, gravel, and stones from the formed wood chips. Further, the structure of the wood chips may be loosened before the pre-treatment step. The wood-based feedstock may contain a certain amount of bark from the log.

[0051] Providing the wood-based feedstock may include purchasing the wood-based feedstock. The purchased wood-based feedstock may include purchased wood chips or sawdust derived from wood-based raw materials.

[0052] The pretreatment of the wood-based feedstock may include one or more different pretreatment steps. During the different pretreatment steps, the wood-based feedstock varies accordingly. The purpose of the pretreatment step is to form a slurry for further processing.

[0053] The pretreatment may include subjecting the wood-based feedstock to pre-steaming. The pretreatment may include subjecting the wood-based feedstock received from mechanical treatment to pre-steaming. The pretreatment may include subjecting the wood-based feedstock to pre-steaming to form a pre-steamed wood-based feedstock before subjecting it to impregnation treatment. The pretreatment may include impregnation treatment and steam explosion treatment, and may include subjecting the wood-based feedstock to pre-steaming before subjecting it to impregnation treatment and subsequent steam explosion treatment.

[0054] The pre-steaming of the wood-based feedstock may be carried out at atmospheric pressure using steam having a temperature of 100 - 130°C. During the pre-steaming, the wood-based feedstock is treated with low-pressure steam. The pre-steaming may be carried out using steam having a temperature of less than 100°C, or less than 98°C, or less than 95°C. The pre-steaming has the additional usefulness of reducing or removing air from inside the wood-based feedstock. The pre-steaming may be carried out in at least one pre-steaming reactor.

[0055] The pretreatment may include subjecting the wood-based feedstock to impregnation treatment with an impregnating solution containing sulfuric acid. The impregnating solution may consist of sulfuric acid and water. The impregnating solution may contain sulfuric acid in an amount of up to 20% by weight based on the total weight of the impregnating solution. By subjecting the wood-based feedstock to impregnation treatment, an impregnated wood-based feedstock containing sulfuric acid in an amount of at least 0.5% by weight based on the total dry matter content of the wood-based feedstock may be formed.

[0056] The impregnation treatment may be performed on the wood-based feedstock received from mechanical treatment and / or pre-steam treatment. The wood-based feedstock may be transferred to the impregnation treatment from mechanical treatment and / or pre-steam treatment using a feeder. The feeder may be a screw feeder such as a plug screw feeder. The feeder may compress the wood-based feedstock during transfer. Then when the wood-based feedstock enters the impregnation treatment, the wood-based feedstock may expand and absorb the impregnating liquid.

[0057] The sulfuric acid may be dilute sulfuric acid. The total amount of acid added to the wood-based feedstock may be 0.3 - 5.0% w / w, 0.5 - 3.0% w / w, 0.6 - 2.5% w / w, 0.7 - 1.9% w / w, or 1.0 - 1.6% w / w based on the total dry matter content of the wood-based feedstock. The impregnating liquid may act as a catalyst that affects the hydrolysis of hemicellulose in the wood-based feedstock. In one embodiment, the sulfuric acid catalyzes the hydrolysis of hemicellulose in the wood-based feedstock to monomeric sugars.

[0058] The impregnation treatment may be carried out in at least one impregnation reactor or impregnation vessel. In one embodiment, two or more impregnation reactors are used. The transfer from one impregnation reactor to another may be carried out using a screw feeder.

[0059] The impregnation treatment may be carried out by conveying the wood-based feedstock through at least one impregnation reactor at least partially filled with the impregnating liquid, i.e., the wood-based feedstock is transferred to the impregnation reactor, sinks into the impregnating liquid therein, and is transferred from the impregnation reactor so that the wood-based feedstock is uniformly impregnated with the impregnating liquid. As a result of the impregnation treatment, an impregnated wood-based feedstock is formed. The impregnation treatment may be carried out as a batch process or continuously.

[0060] The residence time of the wood-based feedstock in the impregnation reactor, i.e., the time during which the wood-based feedstock is in contact with the impregnating liquid, may be 1 to 30 minutes. The temperature of the impregnating liquid may be, for example, 20 to 99 °C, or 40 to 95 °C, or 60 to 93 °C. Keeping the temperature of the impregnating liquid below 100 °C has the additional utility of preventing or reducing the dissolution of hemicellulose. In one embodiment, the impregnation treatment is carried out at a temperature of 80 to 100 °C, or 90 to 99 °C for 1 to 30 minutes.

[0061] After the impregnation treatment, the impregnated wood-based feedstock may remain in a storage tank or silo, for example, for a predetermined period of time to stabilize the impregnating liquid absorbed by the wood-based feedstock. This predetermined time may be 15 to 60 minutes, or for example, about 30 minutes.

[0062] In one embodiment, the wood-based feedstock is subjected to an impregnation treatment with dilute sulfuric acid having a concentration of 1.32% w / w and a temperature of 92 °C.

[0063] The pretreatment may include subjecting the wood-based feedstock to a steam explosion treatment. The wood-based feedstock from the impregnation treatment may be subjected to a steam explosion treatment. That is, the pretreatment may include subjecting the impregnated wood-based feedstock to a steam explosion treatment to form a steam-treated wood-based feedstock.

[0064] Accordingly, the pretreatment may include subjecting the wood-based material to mechanical treatment to form a wood-based feedstock, subjecting the wood-based feedstock to pre-steam treatment to form a pre-steam-treated feedstock, subjecting the pre-steam-treated wood-based feedstock to impregnation treatment to form an impregnated wood-based feedstock, and subjecting the impregnated wood-based feedstock to steam explosion treatment. In one embodiment, the pretreatment in ii) includes pre-steam treatment of the wood-based feedstock, impregnation treatment of the pre-steam-treated wood-based feedstock, and steam explosion treatment of the impregnated wood-based feedstock. In one embodiment, the pretreatment in ii) includes impregnation treatment of the wood-based feedstock and steam explosion treatment of the impregnated wood-based feedstock. That is, the wood-based feedstock subjected to impregnation treatment may then be subjected to steam explosion treatment. Also, the wood-based feedstock subjected to pre-steam treatment may be subjected to impregnation treatment, and then the impregnated wood-based feedstock subjected to impregnation treatment may be subjected to steam explosion treatment.

[0065] The wood-based feedstock can be stored, for example, in a chip bin or a silo between different treatments. Alternatively, the wood-based feedstock may be transported from one treatment to another in a continuous manner.

[0066] The pretreatment may include subjecting the impregnated wood-based feedstock to steam explosion treatment to form a steam-treated wood-based feedstock. The amount of sulfuric acid in the steam explosion treatment may be 0.10 to 0.75% by weight based on the total dry matter content of the wood-based feedstock. The steam explosion treatment may be carried out by treating the impregnated wood-based feedstock with steam having a temperature of 130 to 240 °C, or 180 to 200 °C, or 185 to 195 °C under a pressure of 0.17 to 3.25 MPaG, and then suddenly depressurizing this feedstock. The feedstock may be treated with steam for 1 to 20 minutes, or 1 to 18 minutes, or 2 to 15 minutes, or 4 to 13 minutes, or 3 to 10 minutes, or 3 to 8 minutes, and then a sudden explosive depressurization of the steam-treated wood-based feedstock may be carried out.

[0067] In this specification, the term "steam explosion treatment" may refer to a process of hemihydrolysis in which a feedstock is treated in a reactor (steam explosion reactor) with steam having a temperature of 130 to 240 °C, or 180 to 200 °C, or 185 to 195 °C under a pressure of 0.17 to 3.25 MPaG, followed by a sudden explosive decompression of the feedstock, as a result of which the fibrous structure of the feedstock ruptures.

[0068] In one embodiment, the amount of sulfuric acid in the steam explosion treatment may be 0.10 to 0.75% by weight based on the total dry matter content of the wood-based feedstock. The amount of acid present during the steam explosion treatment may be determined by measuring the sulfur content of the liquid of the steam-treated wood-based feedstock or the liquid portion of the steam-treated wood-based feedstock after the steam explosion treatment. The amount of sulfuric acid in the steam explosion reactor may be determined by subtracting the amount of sulfur in the wood-based feedstock from the measured amount of total sulfur in the steam-treated wood-based feedstock.

[0069] The steam explosion treatment may be carried out in a pressure reactor. The steam explosion treatment may be carried out in a pressure reactor by treating the impregnated wood-based feedstock with steam having a temperature of 130 to 240 °C, or 180 to 200 °C, or 185 to 195 °C under a pressure of 0.17 to 3.25 MPaG, and then suddenly depressurizing this feedstock. The impregnated wood-based feedstock may be introduced into the pressure reactor using a compression conveyor, such as a screw feeder. When a screw feeder is used, during transportation by the screw feeder, the acid in liquid form is removed, and a part of the impregnating liquid absorbed by the feedstock is removed as pressate, but most of it remains in the feedstock. The impregnated wood-based feedstock may be introduced into the pressure reactor together with steam and / or gas. The pressure of the pressure reactor can be controlled by adding steam. The pressure reactor may operate in a continuous mode or as a batch process. The impregnated wood-based feedstock, for example, the wood-based feedstock subjected to the impregnation treatment, may be introduced into the pressure reactor at a temperature of 25 to 140 °C. The residence time of the feedstock in the pressure reactor may be 0.5 to 120 minutes. The term "residence time" should be understood in this specification, unless otherwise specified, as the time between when the feedstock is introduced into or enters the pressure reactor and when the feedstock exits or is discharged from the pressure reactor.

[0070] As a result of the semi-hydrolysis of the wood-based feedstock affected by the steam explosion treatment in the reactor, the hemicellulose present in the wood-based feedstock may be hydrolyzed or decomposed into, for example, oligomers and / or monomers of xylose. Hemicellulose contains polysaccharides such as xylan, mannan, and glucan. Thus, xylan is hydrolyzed into xylose, which is a monosaccharide. In one embodiment, 87 to 95%, or 89 to 93%, or 90 to 92% of the xylan present in the impregnated wood-based feedstock is converted into xylose.

[0071] Thus, steam explosion of the feedstock may result in the formation of an output stream. The output stream from the steam explosion may be subjected to steam separation. The output stream from the steam explosion may be mixed or combined with a liquid, such as water. The output stream of the steam explosion may be mixed with a liquid to form a slurry. This liquid may be pure water or water containing C5 sugars. The water containing C5 sugars may be recycled water from separating and / or washing a fraction containing solid cellulose particles prior to enzymatic hydrolysis. The output stream may be mixed with the above liquid, and the resulting mass may be mechanically homogenized to break up aggregates. The pretreatment may include mixing the steam-treated woody feedstock with a liquid to form a slurry.

[0072] Thus, as a result of the pretreatment, a slurry may thus be formed. This slurry may include a liquid phase and a solid phase. The slurry may include solid cellulose particles. The slurry may be separated into a liquid fraction and a fraction containing solid cellulose particles.

[0073] The method may include separating the liquid fraction and the fraction containing solid cellulose particles by a solid-liquid separation process and recovering the liquid fraction as a feedstock for hardwood-derived carbohydrates. The solid-liquid separation process may include washing. The washing may be continued until the amount of soluble organic components in the fraction containing solid cellulose particles is 0.5 to 5 wt%, or 1 to 4 wt%, or 1.5 to 3 wt% based on the total dry matter content.

[0074] Separating the liquid fraction and the fraction containing solid cellulose particles may be performed by displacement washing or countercurrent washing. Thus, the solid-liquid separation process may be selected from displacement washing and countercurrent washing.

[0075] Displacement washing, or in other words replacement washing, is a method of separating solids from liquids using a relatively small amount of washing liquid. Therefore, displacement washing may be considered an operation capable of washing solid particles with a minimum amount of washing liquid such as water.

[0076] In countercurrent washing, the washing liquid such as water flows in the reverse direction relative to the generally forward movement of the fraction containing solid cellulose particles. Similar to the case of displacement washing, countercurrent washing may also significantly reduce the consumption of the washing liquid.

[0077] Countercurrent washing may include at least two solid-liquid separation steps and one dilution with a washing solution between those steps. The washing solution may be clean water. The amount of water required may vary depending on the total number of solid-liquid separation steps carried out, the total dry matter content in the feed of the solid-liquid separation step, and the total dry matter content in the fraction containing solid cellulose particles after each solid-liquid separation step.

[0078] The washing liquid may be fresh washing water or recycled washing water. The washing water may be fresh water, drinking water, or a sugar-containing liquid with a low sugar content. The electrical conductivity of the washing liquid may be about 0.1 mS / cm.

[0079] The ratio of the washing liquid used to the solid may be 0.5:1 to 8:1 (w / w), or 0.5:1 to 5:1 (w / w), or 0.5:1 to 3:1 (w / w), or 0.5:1 to 2:1 (w / w) in the case of displacement washing. The ratio of the washing liquid used to the solid may be 0.5:1 to 8:1 (w / w), or 0.5:1 to 5:1 (w / w) in the case of countercurrent washing.

[0080] The progress of the displacement washing and the countercurrent washing may be monitored by measuring the electrical conductivity of the liquid fraction recovered from this process. If the electrical conductivity of the liquid fraction is below a predetermined threshold of 0.35 mS / cm, it may be concluded that a desired amount of C5 sugars and other soluble impurities have been removed from the fraction containing the solid cellulose particles, and the washing may be terminated. In one embodiment, the washing is continued until the electrical conductivity of the liquid fraction reaches 0.1 - 1.0 mS / cm or 0.2 - 0.5 mS / cm.

[0081] Alternatively, the above separation may be carried out by filtration, decantation, and / or centrifugation. The filtration may be vacuum filtration, filtration based on the use of reduced pressure, filtration based on the use of overpressure, or a filter press. The decantation may be repeated to improve the separation.

[0082] The above separation and / or washing may, if necessary, concentrate the liquid fraction, i.e., the feedstock of the hardwood-derived carbohydrate, to provide the feedstock of the hardwood-derived carbohydrate in the form of a liquid fraction having a desired total dry matter content, for example, including the recirculation of the washing liquid.

[0083] Thus, the method for producing the hardwood-derived carbohydrate composition includes a step of providing a feedstock of the hardwood-derived carbohydrate in the form of a liquid fraction having a total dry matter content of 5 - 30% by weight.

[0084] The carbohydrate feedstock derived from hardwood may contain monomeric sugars in an amount of 50 to 80% by weight based on the total dry matter content of the feedstock. The amount of monomeric xylose in the feedstock may be 40 to 60% by weight. In the carbohydrate feedstock derived from hardwood, the weight ratio of monomeric glucose to monomeric xylose may be 0.067 to 0.2. The carbohydrate feedstock derived from hardwood may contain soluble lignin in an amount of 5 to 15% by weight based on the total dry matter content of the feedstock. The carbohydrate feedstock derived from hardwood may contain organic impurities in an amount of 6 to 30% by weight based on the total dry matter content of the feedstock. The carbohydrate feedstock derived from hardwood may contain carboxylic acids in an amount of 5 to 20% by weight based on the total dry matter content of the feedstock. The carbohydrate feedstock derived from hardwood may contain inorganic impurities in an amount of 0 to 6% by weight, or 0.1 to 3% by weight, or 0.2 to 2% by weight, or 0.3 to 1% by weight based on the total dry matter content of the feedstock.

[0085] In one embodiment, the liquid - fraction form of the carbohydrate feedstock derived from hardwood is filtered through a safety filter having a pore size of 2 to 50 μm before subjecting the carbohydrate feedstock derived from hardwood to treatment with granular activated carbon. By subjecting the carbohydrate feedstock derived from hardwood to filtration before treatment with granular activated carbon, removal of solids becomes possible.

[0086] The pH of the liquid - fraction form of the carbohydrate feedstock derived from hardwood may be adjusted to 2 to 2.7 before subjecting the carbohydrate feedstock derived from hardwood to treatment with granular activated carbon. Adjusting the pH may affect color removal.

[0087] The carbohydrate feedstock derived from hardwood is subjected to treatment with granular activated carbon. Granular activated carbon, or in other words, granular activated carbon, may be considered as activated carbon retained on a 50 - mesh sieve. The particle size (grain size) of the granular activated carbon may be 0.2 to 2 mm, or 0.3 to 1.5 mm. The treatment with granular activated carbon has the additional utility of reducing or removing soluble lignin from the feedstock.

[0088] After the activated carbon treatment, the treated feedstock may be collected. The collection of the feedstock may be continued until a preset absorbance value is reached. That is, the treatment using granular activated carbon may be continued until the carbon is saturated and the quality of the feedstock falls below a predetermined quality level.

[0089] In one embodiment, the collection of the feedstock of hardwood-derived carbohydrates subjected to granular activated carbon treatment ends between 5 and 100, or 7 and 80, 9 and 70, or 10 and 60, or 20 and 55, or 30 and 50, or 40 and 45 bed volumes (BV). In one embodiment, the collection of the feedstock of hardwood-derived carbohydrates subjected to granular activated carbon treatment ends between 30 and 60, or 35 and 55, or 40 and 50, or 10 and 30, or 12 and 25, or 14 and 20 bed volumes (BV).

[0090] In one embodiment, the feedstock of hardwood-derived carbohydrates subjected to granular activated carbon treatment is collected in 1 to 60, or 1 to 55, or 1 to 50, or 1 to 45, or 1 to 40, or 1 to 35, or 1 to 30, or 1 to 25, or 1 to 20, or 1 to 15, or 1 to 10, or 1 to 9 bed volumes.

[0091] In this specification, the expression "bed volume" should be understood to refer to the volume of granular activated carbon in a column containing granular activated carbon, unless otherwise specified.

[0092] The flow rate of the feedstock of hardwood-derived carbohydrates passing through the granular activated carbon may be 0.5 to 2 BV / h. The volume of the column containing the granular activated carbon is 15 to 30 m 3 , or 18 to 25 m 3 and may be. The temperature may be maintained at 40 to 80 °C, or 45 to 75 °C, or 50 to 70 °C during the treatment using granular activated carbon.

[0093] In one embodiment, the granular activated carbon treatment is carried out as a batch process.

[0094] Next, the pH of the feedstock of the activated carbon-treated hardwood-derived carbohydrate may be adjusted to a pH value of 2.2 to 3.0. The pH value may be adjusted using, for example, sodium hydroxide, potassium hydroxide, or the like. Further, by adjusting the pH value, it can be ensured that organic acids that may be present in the feedstock are removed together with the condensate.

[0095] Next, the above feedstock having a pH value of 2.2 to 3.0 may be subjected to evaporation. Evaporation may be carried out by using steam having a temperature of 75 to 85 °C, or 77 to 83 °C, or about 79 °C in a vacuum. The temperature of the feedstock may be 65 to 70 °C, or 67 to 69 °C during evaporation.

[0096] Evaporation may be continued until the total dry matter content of the feedstock after evaporation is 30 to 80% by weight, or 40 to 75% by weight, or 50 to 70% by weight. Evaporation has the additional utility of affecting the amount of organic acid that may be removed from the feedstock. Further, evaporating the feedstock until the total dry matter content of the feedstock is, for example, 50 to 70% by weight has the additional utility of being beneficial for storing and transporting the hardwood-derived carbohydrate composition.

[0097] The method disclosed herein has the additional utility of providing a hardwood-derived carbohydrate composition having a high content of monomeric sugars, particularly monomeric xylose. The method disclosed herein has the additional utility of providing a hardwood-derived carbohydrate composition in which the amount of soluble lignin is reduced, thereby reducing the risk of lignin precipitation during storage and transportation of the hardwood-derived carbohydrate composition. This makes the transportation of the hardwood-derived carbohydrate composition easier.

[0098] The hardwood-derived carbohydrate composition has properties that make the composition itself useful, for example, in ethanol fermentation. The hardwood-derived carbohydrate composition has additional utility in that it meets the purity characteristics required for further use in a process for producing a sweetener such as xylitol. This hardwood-derived carbohydrate composition has additional utility in that the composition may be used to produce biogas.

Examples

[0099] Reference will now be made in detail to embodiments of the present disclosure.

[0100] The following description discloses several embodiments in sufficient detail for those skilled in the art to utilize the methods based on the present disclosure. Since many of the steps of the above embodiments will be apparent to those skilled in the art based on the present disclosure, not all steps of the embodiments will be discussed in detail.

[0101] Example 1 - Production of Hardwood-Derived Carbohydrate Composition In this example, a hardwood-derived carbohydrate composition was prepared.

[0102] First, a wood-based feedstock containing beech wood chips was prepared. Next, this wood-based feedstock was subjected to pretreatment as follows.

[0103] The above wood-based feedstock was subjected to pre-steam treatment. The pre-steam treatment of the wood-based feedstock was carried out at atmospheric pressure for 180 minutes using steam having a temperature of 100 °C. Subsequently, the pre-steamed feedstock was subjected to impregnation treatment with dilute sulfuric acid having a concentration of 1.32% w / w and a temperature of 92 °C. The pre-steamed wood-based feedstock was allowed to be affected by the impregnating liquid for 30 minutes. Subsequently, the acid-impregnated wood-based feedstock was subjected to steam explosion treatment. This steam explosion treatment was carried out by treating the impregnated wood-based feedstock with steam having a temperature of 191 °C and then suddenly depressurizing the wood-based feedstock to atmospheric pressure. The amount of sulfuric acid in the steam explosion reactor was 0.33% by weight based on the total dry matter content of the wood-based feedstock. In the determination of the amount of sulfuric acid, the sulfur content of the wood was 0.02% by weight based on the total dry matter content of the wood used.

[0104] In the pretreatment, the conversion rate of xylan in the wood-based feedstock to xylose was 91%, and the ratio of solubilized glucose to solubilized xylose, as determined by HPLC-RI as detailed below, was 0.14. Subsequently, the steam-treated wood-based feedstock was mixed with water in a mixing vessel.

[0105] As a result of the above pretreatment steps, a slurry was formed. This slurry contained a liquid fraction and a fraction containing solid cellulose particles. Subsequently, this slurry was separated into a liquid fraction and a fraction containing solid cellulose particles by a solid-liquid separation process. The solid-liquid separation process was countercurrent washing in this example. Countercurrent washing was continued until the amount of soluble components in the fraction containing solid cellulose particles reached 2.0% by weight based on the total dry matter content. The dry solid content of the fraction containing solid cellulose particles was 32% by weight after washing. The total dry matter content of the liquid fraction was 9% by weight.

[0106] The above liquid fraction was recovered as a feedstock for hardwood-derived carbohydrates. Subsequently, this feedstock for hardwood-derived carbohydrates was subjected to a treatment using granular activated carbon packed in a column. The feedstock for hardwood-derived carbohydrates subjected to the granular activated carbon treatment was collected. The granular activated carbon had the following properties: manufactured from pine wood; particle size 0.4 - 1.8 mm; density 0.24 kg / dm 3 ; iodine value 1025 mg / g; ash content 2.5 - 3%.

[0107] The absorbance of the provided feedstock for hardwood-derived carbohydrates was 3.05. Collection of the feedstock was continued until the absorbance of the collected feedstock became 65% of the absorbance of the provided feedstock for hardwood-derived carbohydrates. Collection was terminated or stopped during 52 bed volumes, that is, 1 - 52 bed volumes were collected, and at that time the absorbance was 1.98. The volume of the column containing the granular activated carbon was 20 m 3 It was.

[0108] Subsequently, the pH of the collected feedstock was adjusted to a pH value of 2.9 by using sodium hydroxide (NaOH), and then the feedstock was evaporated until the total dry matter content of the feedstock became 65% by weight. The temperature of the steam used for evaporation was 79 °C in a vacuum. The temperature of the feedstock during evaporation was 68 °C.

[0109] As a result, a hardwood-derived carbohydrate composition was formed.

[0110] The recovered hardwood-derived carbohydrate composition was analyzed by HPLC-RI using a Waters e2695 Alliance Separation module, a Waters 2998 Photodiode Array, and a Waters 2414 Refractive Index detector. Separation was achieved using a 300 mm × 7.8 mm Bio-Rad Aminex HPX-87 column equipped with a Micro-Guard Deashing column and a Carbo-P guard column in series. Ultra-pure water was used as the eluent.

[0111] The amount of oligomeric sugar in the sample was determined by hydrolyzing the oligomeric sugar into monomeric sugars by acid hydrolysis, analyzing the acid-hydrolyzed sample by HPLC-RI, and comparing the results with those of the non-hydrolyzed sample. The amount of oligomeric sugar was calculated by subtracting the amount of monomeric sugar in the untreated sample.

[0112] The results are shown in the following table.

[0113]

Table 1

[0114] It will be apparent to those skilled in the art that, with the progress of technology, the basic idea may be implemented in various ways. Therefore, the embodiments are not limited to the above examples, and instead, the embodiments may vary within the scope of the claims.

[0115] The embodiments described so far in this specification may be used in any combination with each other. Some of the embodiments may be combined together to form further embodiments. The hardwood-derived carbohydrate compositions, methods, or uses disclosed in this specification may include at least one of the embodiments described above in this specification. It will be understood that the above benefits and advantages may relate to one embodiment or to several embodiments. Embodiments are not limited to those that solve any or all of the stated problems or have any or all of the stated benefits and advantages. It will be further understood that references to "a" item refer to one or more of these items. The term "comprising" is used in this specification to mean including the feature or act recited after the term "comprising" (before the term "including") without precluding the presence of one or more additional features or acts.

Claims

1. A broadleaf tree-derived carbohydrate composition comprising 65 to 85% by weight of monomer sugars based on the total dry matter content of the carbohydrate composition, wherein the monomer sugars comprise monomer xylose, the amount of monomer xylose in the carbohydrate composition is 50 to 70% by weight based on the total dry matter content of the carbohydrate composition, and the carbonyl content of the carbohydrate composition is 5,000 to 20,000 μg / g based on the total dry matter content of the carbohydrate composition.

2. The broadleaf tree-derived carbohydrate composition according to claim 1, wherein the amount of monomer xylose in the carbohydrate composition is 55 to 65% by weight based on the total dry content of the carbohydrate composition.

3. The broadleaf tree-derived carbohydrate composition according to claim 1, wherein the carbonyl content of the carbohydrate composition is 7,500 to 17,500 μg / g or 10,000 to 15,000 μg / g based on the total dry content of the carbohydrate composition.

4. The carbohydrate composition is a broadleaf tree-derived carbohydrate composition according to claim 1, which exhibits an ICUMSA color value of 5,000 to 40,000 IU, or 7,500 to 30,000 IU, or 10,000 to 20,000 IU.

5. The broadleaf tree-derived carbohydrate composition according to claim 1, wherein the carbohydrate composition comprises 1.0 to 4.0% by weight, or 1.25 to 3.75% by weight, or 1.5 to 3.5% by weight of soluble lignin, based on the total dry content of the carbohydrate composition.

6. The hardwood-derived carbohydrate composition according to claim 1, wherein the electrical conductivity of a 65% aqueous solution of the carbohydrate composition is 0.3 to 2.0 mS / cm, or 0.4 to 1.5 mS / cm, or 0.5 to 1.0 mS / cm, as determined according to SFS-EN 27888.

7. The broadleaf tree-derived carbohydrate composition according to claim 1, wherein the carbohydrate composition comprises rhamnose in an amount of 0.25 to 5% by weight, or 0.5 to 4.5% by weight, or 0.75 to 4.0% by weight, based on the total dry content of the carbohydrate composition.

8. The broadleaf tree-derived carbohydrate composition according to claim 1, wherein the carbohydrate composition comprises 5 to 20% by weight, or 5.5 to 18% by weight, or 6 to 16% by weight, of the total dry content of the carbohydrate composition, in an amount of carboxylic acid.

9. A method for producing a broadleaf tree-derived carbohydrate composition according to any one of claims 1 to 8, i) A step of providing a raw material for supplying hardwood-derived carbohydrates in the form of a liquid fraction having a total dry matter content of 5 to 30% by weight, ii) A step of subjecting the supply raw material of broadleaf tree-derived carbohydrates to treatment using granular activated carbon, iii) A step of collecting the supply material of hardwood-derived carbohydrates subjected to granular activated carbon treatment, wherein the collection of the supply material is continued until the absorbance of the collected supply material reaches a maximum of 70% of the absorbance of the supplied hardwood-derived carbohydrate supply material, iv) A step of adjusting the pH of the collected hardwood-derived carbohydrate raw material to a pH value of 2.2 to 3.0, v) A step of evaporating the supply raw material having a pH value of 2.2 to 3.0 until the total dry matter content of the supply raw material is 30 to 80% by weight. A method for producing the broadleaf tree-derived carbohydrate composition, comprising the above-mentioned broadleaf tree-derived carbohydrate composition.

10. Use of the hardwood-derived carbohydrate composition according to any one of claims 1 to 8 in a fermentation process for the production of sweeteners or for the production of biogas.

11. The use according to claim 10, wherein the fermentation process is ethanol fermentation.

12. The use according to claim 10, wherein the production of the sweetener includes the crystallization of xylose from the broadleaf tree-derived carbohydrate composition.

13. The method according to claim 9 for reducing the amount of soluble lignin in a hardwood-derived carbohydrate composition in order to reduce lignin precipitation during storage and / or transport of the hardwood-derived carbohydrate composition.