A wood-derived carbohydrate composition and the use thereof

Abstract

Disclosed is a wood-derived carbohydrate composition, wherein the carbohydrate composition comprises at least 40 weight-% of carbohydrates based on the total dry matter content of the carbohydrate composition, at least 30 weight-% of the carbohydrates are xylose, and at least 50 weight-% of the xylose is oligomeric xylose. Further is disclosed the use of the wood-derived carbohydrate composition.

Description

[0001] A WOOD-DERIVED CARBOHYDRATE COMPOSITION AND THE USE

[0002] THEREOF

[0003] TECHNICAL FIELD

[0004] The present disclosure relates to a wood- derived carbohydrate composition . Further, the present disclosure relates to the use of the wood-derived carbohydrate composition .

[0005] BACKGROUND

[0006] Different methods are known for converting biobased raw material , such as lignocellulosic biomass , into a liquid stream of various sugars . Being able to provide sufficiently pure carbohydrate composition with properties suitable for different applications has still remained as a task for researchers .

[0007] SUMMARY

[0008] Disclosed is a wood-derived carbohydrate composition, wherein :

[0009] - the carbohydrate composition comprises at least 40 weight-% of carbohydrates based on the total dry matter content of the carbohydrate composition,

[0010] - at least 30 weight-% of the carbohydrates are xylose , and at least 50 weight-% of the xylose is oligomeric xylose .

[0011] Further is disclosed the use of the wood- derived carbohydrate composition as disclosed in the current disclosure for the production of biogas , ethanol , and an animal feed additive .

[0012] BRIEF DESCRIPTION OF THE DRAWINGS The accompanying drawing, which is included to provide a further understanding of the embodiments and constitute a part of this specification, illustrates an embodiment . In the drawing :

[0013] Figs , la and lb present a set-up of the improved simulated moving bed chromatography ( I SMB) process used in example 1 .

[0014] DETAILED DESCRIPTION

[0015] The present disclosure relates to a wood- derived carbohydrate composition, wherein :

[0016] - the carbohydrate composition comprises at least 40 weight-% of carbohydrates based on the total dry matter content of the carbohydrate composition,

[0017] - at least 30 weight-% of the carbohydrates are xylose , and at least 50 weight-% of the xylose is oligomeric xylose .

[0018] The present disclosure further relates to the use of the wood-derived carbohydrate composition as disclosed in the current disclosure for the production of biogas , ethanol , and a feed additive .

[0019] In one embodiment , the wood-derived carbohydrate composition is a liquid wood-derived carbohydrate composition . In one embodiment , the wood- derived carbohydrate composition is in liquid form .

[0020] The wood-derived carbohydrate compos ition, or the carbohydrate composition as also used in the current disclosure , as disclosed in the current specification relates to a composition that comprises carbohydrates but may also in addition comprise additional components and / or elements e . g . as disclosed in the current specification . Thus , the "wood-derived carbohydrate composition" may be considered as a "wood-derived carbohydrate-containing composition" or a "wood-derived composition comprising carbohydrates" . The wood-derived carbohydrate composition may be prepared starting from or derived from wood . In one embodiment , the wood-derived carbohydrate composition is a hardwood-derived carbohydrate composition . The wood-derived carbohydrate composition may be prepared starting from wood species such as beech, birch, ash, or their combination .

[0021] In one embodiment , the carbohydrate composition comprises 40 - 90 weight-% , or 50 - 85 weight-% , or 60 - 80 weight-% , of carbohydrates based on the total dry matter content of the carbohydrate composition . When used as an animal feed additive , the high amount of carbohydrates in the carbohydrate composition may be beneficial for the intake of energy . In addition, a high amount of carbohydrates is of relevance when producing ethanol or biogas as the carbohydrates are the reacting part of the composition in such a production process . The high amount of carbohydrates is of use during the fermentation process when producing ethanol where it can be used by the fermenting micro-organisms . Thus , the wood-derived carbohydrate composition has the added utility of being a low-cost raw material for ethanol production as well as for biogas production .

[0022] In one embodiment , the at least 35 weight-% of the carbohydrates are xylose . In one embodiment , at least 60 weight-% , or at least 70 weight-% , of the xylose is oligomeric xylose . When used as an animal feed additive , the high amount of oligomeric xylose in the carbohydrate composition may be beneficial for the intake of energy . In addition , a high amount of xylose is of relevance when producing ethanol or biogas as the carbohydrates are the reacting part of the composition in such a production process .

[0023] The wood-derived carbohydrate composition as disclosed in the current disclosure has the further added utility of founding use as a food supplement for humans .

[0024] The amount of monomeric carbohydrates , such as the amount of monomeric C5 sugars and monomeric C6 sugars , may be determined both qualitatively and quantitatively by high-performance liquid chromatography (HPLC) by comparing to standard samples . Examples of analysis methods can be found in e . g . 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 2012 .

[0025] The amount of oligomeric carbohydrates may be determined with acid hydrolysis pretreatment and high- performance liquid chromatography (HPLC) analysis . In the pretreatment , a sample of the carbohydrate composition is contacted with 72 weight-% sulfuric acid and kept at 30 ° C temperature for 30 min . After this the same is put to an autoclave and kept there at a temperature of 121 ° C for 1 h . Thereafter, the amount of monosaccharides in the treated sample may be determined using the above HPLC method . Prior to the analysis of the monosaccharides , the acidic solution is neutrali zed with calcium carbonate (CaCOs ) and filtered . The amount of oligomeric sugars in the original sample may be obtained by subtracting the amount of monosaccharides determined from the sample before the acid hydrolysis pretreatment from the amount of monosaccharides determined from the acid hydrolysis pretreated sample .

[0026] As used herein, any weight-percentages are given as percent of the total dry matter content of the carbohydrate composition unless specified otherwise . Similarly, other fractions of weight (ppm etc . ) may also denote a fraction of the total dry matter content of the carbohydrate composition unless specified otherwise .

[0027] By the expression "oligosaccharide" or that the sugar is "oligomeric" should be understood in this specification, unless otherwise stated, as referring to a sugar molecule consisting of two or more monomers coupled or connected to each other .

[0028] By the expression "monosaccharide" or that the sugar is "monomeric" should be understood in this specification, unless otherwise stated, as referring to a sugar molecule present as a monomer, i . e . not coupled or connected to any other sugar molecule ( s ) .

[0029] In the current specification the amounts of different components / elements in the wood-derived carbohydrate composition are presented in weight-% based on the total dry matter content of the carbohydrate composition . In this specification the term "total dry matter content of the carbohydrate composition" may refer to the weight of the carbohydrate composition as determined by allowing a sample of the carbohydrate composition to be absorbed on a glass fiber filter placed in an aluminium cup . The aluminium cup with the glass fiber filter is weighted before and after the sample has been absorbed . The sample in the aluminium cup is allowed to dry in an oven overnight at a temperature of 60 ° C . Immediately after this , the dried sample absorbed in the glass fiber is weighted with the cup . Dry solids content is calculated from the difference in mass of the wet and dried samples .

[0030] As is clear to the skil led person, the total amount of the different components / elements in the wood- derived carbohydrate composition may not exceed 100 weight-% . The amount in weight-% of the di fferent components / elements in the wood-derived carbohydrate composition may vary within the given ranges .

[0031] In one embodiment , at most 50 weight-% , or at most 45 weight-% , or at most 40 weight-% , of the carbohydrates are C6 sugars. By the expression "C6 sugars" should be understood in this specification, unless otherwise stated, as referring to glucose, galactose, mannose, fructose, or any mixture or combination thereof. The C6 sugars may be monomeric C6 sugars and / or oligomeric C6 sugars.

[0032] In one embodiment, at least 20 weight-%, or at least 25 weight-%, or at least 30 weight-%, of the C6 sugars are mannose and / or galactose. Mannose and galactose are suitable raw materials to be present in the carbohydrate composition when used for the production of biogas.

[0033] In one embodiment, the carbohydrate composition comprises C5 sugars and at least 1.0 weight- % , or at least 2.0 weight-%, or at least 3.0 weight-%, of the C5 sugars are arabinose. The presence of C5 sugars in the carbohydrate composition is suitable when the carbohydrate composition is used for producing biogas or bioethanol.

[0034] By the expression "C5 sugars" should be understood in this specification, unless otherwise stated, as referring to arabinose, xylose, or any mixture or combination thereof. The C5 sugars may be monomeric C5 sugars and / or oligomeric C5 sugars.

[0035] In one embodiment, the carbohydrate composition comprises soluble lignin in a total amount of 10 - 24 weight-%, or 12 - 22 weight-%, or 14 - 20 weight-%, based on the total dry matter content of the carbohydrate composition. The presence of soluble lignin in the carbohydrate composition may evidence that the carbohydrate composition is derived from wood. The presence of soluble lignin in the carbohydrate composition has the added utility of providing the carbohydrate composition with antioxidant properties when used e.g. as an animal feed additive. The presence of soluble lignin may thus improve the preservation of the carbohydrate composition. The amount of soluble lignin may be determined by UV-VIS absorption spectroscopy in the following manner: The amount of soluble lignin present in the carbohydrate composition is determined by diluting a sample of carbohydrate composition so that its absorbance at 205 nm is 0.2 - 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 / 1 may then be calculated using the where

[0036] A is absorbance of the sample, a is the absorptivity coefficient 0.110 1 / mgcm, and D is a dilution factor.

[0037] In one embodiment, the carbohydrate composition comprises sulphur in a total amount of 0.5 - 6.0 weight-%, or 1.0 - 4.0 weight-%, based on the total dry matter content of the carbohydrate composition. The amount of sulphur may be determined according to standard SFS-EN ISO 11885 (2009) . The presence of sulphur in the carbohydrate composition may evidence that the carbohydrate composition is produced by a method comprising a sulphur acid impregnation treatment, instead of e.g. using an autohydrolysis process .

[0038] In one embodiment, wherein the conductivity of a 30 % aqueous solution of the carbohydrate composition is 2 - 10 mS / cm, or 4 - 8 mS / cm, when determined according to SFS-EN 27888. The conductivity of the carbohydrate composition correlates with the amount of sodium present in the carbohydrate composition. The low conductivity of the carbohydrate composition may thus indicate that the carbohydrate composition comprises only a small amount of salts. A higher amount of salts could be harmful e.g. when using the carbohydrate composition for fermentation during ethanol production.

[0039] In one embodiment, wherein the ICUMSA color value of an aqueous solution of the carbohydrate composition is 250000 - 600000 IU, or 300000 - 550000 IU, or 350000 - 500000 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 filtering the sample through a 0.45 pm filter before analysis. The ICUMSA color value may be used as an indication about the amount of soluble lignin present in the carbohydrate composition. The ICUMSA color value correlates with the color of the carbohydrate composition .

[0040] In one embodiment, the pH of the carbohydrate composition is 4 - 7, or 4.5 - 6.5, or 5 - 6.

[0041] In one embodiment, the carbohydrate composition comprises ash in a total amount of 6 - 16 weight-%, or 7 - 14 weight-%, or 8 - 12 weight-%, based on the total dry matter content of the carbohydrate composition. The carbohydrate composition has the added utility of its ash content being on an acceptable level for ethanol fermentation. The amount of ash may be determined as follows: 1-2 g of sample is placed on an annealed crucible and weighted. The sample in the crucible is then dried in an oven at 105 °C temperature for overnight. Weight of the dried sample is then determined. The dried sample in the crucible is then placed into an oven at 525 °C temperature for at least 5 h (3 h heating period, 2 h constant temperature period) . The sample in the crucible is then placed into a desiccator for cooling. If the sample was not completely turned to ash (e.g. black particles can be seen in the ash) , 1-2 ml hydrogen peroxide (30 %) is dropped on the cooled sample. The sample is then put to oven at 525 °C temperature for 30 min. Cooling of the samples in the crucible is done in a desiccator. This treatment is repeated until the ash in crucible has a pale color (e.g. no black particles can be seen) . The ash content can be calculated from > mass of ash in the crucible, a Ash content (%) = - — - - - - - - mass of dried sample, g

[0042] In one embodiment, the carbohydrate composition comprises sodium in a total amount of 65 - 135 g / kg, or 75 - 115 g / kg, based on the total dry matter content of the carbohydrate composition. The amount of sodium may be determined analyzed using inductively coupled plasma-optical emission spectroscopy (ICP-OES) according to standard SFS-EN ISO 11885:2009. The amount of sodium of the carbohydrate composition is on a suitable level for fermentation purposes during ethanol production. A too high amount of sodium may be of harm for fermentation if the salt content of the carbohydrate composition is too high.

[0043] Organic acids may be mentioned as examples of organic impurities that may be present in the carbohydrate composition. 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, as well as various acetates, formiates, and other salts or esters. The quality and quantity of organic impurities in the carbohydrate composition may be determined using e.g. a HPLC coupled with e.g. a suitable detector, infrared (IR) spectroscopy, ultraviolet-visible (UV-VIS) spectroscopy, or nuclear magnetic resonance (NMR) spectrometry. In one embodiment, the carbohydrate composition comprises acetic acid in an amount of 0.5 - 8 weight-%, or 1.0 - 6 weight-%, or 1.5 - 4 weight-%. In one embodiment, the carbohydrate composition comprises 5-HMF in an amount of 0 - 1.5 weight-%, or 0.05 - 0.75 weight-%. The low amount of 5-HMF may evidence that the pretreatment has been successfully carried out when producing the carbohydrate composition.

[0044] One example of providing the wood-based carbohydrate composition as disclosed in the current specification may include the following:

[0045] A feedstock of wood chips, such as hardwood chips, may be subjected to an impregnation treatment with an impregnation liquid. The impregnation liquid may be e.g. a liquid of 0.5 - 2 % sulfuric acid. The impregnation treatment may be carried out at a temperature of 40 - 100 °C for 5 seconds - 60 minutes, or 0.5 - 45 minutes, or 1 - 30 minutes. A higher impregnation time has the added utility of resulting in a higher conversion during the steam explosion treatment making the hemihydrolysis efficient. The impregnation time may affect the ratio of monomeric sugars and oligomeric sugars in the carbohydrate composition. A shorter impregnation time may result in a higher amount of oligomeric sugars, whereby a longer impregnation time may result in a higher amount of monomeric sugars in the carbohydrate composition .

[0046] The impregnated feedstock may then be subjected to steam explosion treatment. The steam explosion treatment may be carried out by treating the impregnated wood-based feedstock with steam having a temperature of 130 - 240 °C, or 180 - 200 °C, or 185 - 195 °C under a pressure of 0.17 - 3.25 MPaG followed by a sudden, explosive decompression of the feedstock. The feedstock may be treated with the steam for 1 - 20 minutes, or 1 - 18 minutes, or 2 - 15 minutes, or 4 - 13 minutes, or 3 - 10 minutes, or 3 - 8 minutes, before the sudden, explosive decompression of the steam-treated feedstock. As a result of the hemihydrolysis of the feedstock affected by the steam explosion treatment, the hemicellulose present in the wood chips of feedstock may become hydrolyzed or degraded into e.g. xylose oligomers and / or monomers. The hemicellulose comprises polysaccharides such as xylan, mannan and glucan. Xylan is thus hydrolyzed into xylose that is a monosaccharide.

[0047] Thus, steam explosion of the feedstock may result in the formation of an output stream. The output stream from the steam explosion treatment may be subjected to steam separation. The output stream from the steam explosion treatment may be mixed or combined with a liquid, e.g. water, to form a slurry. The slurry may comprise a liquid phase and a solid phase. The slurry may be separated into a liquid fraction and a fraction comprising solid cellulose particles. The liquid fraction may then be subjected to concentration, e.g. by evaporation, and, if necessary, the pH of the liquid fraction may be adjusted to 5.5 - 6, e.g. with sodium hydroxide (NaOH) or potassium hydroxide (KOH) , to provide a crude liquid fraction. The crude liquid fraction may have a total dry matter content of 30 - 70 weight- % , or 40 - 60 weight-%, or 45 - 55 weight-%, or 40 - 50 weight-%. The crude liquid fraction may have a xylose content of 40 - 60 weight-%, or 45 - 55 weight-%, based on the total dry matter content of the crude liquid fraction .

[0048] The crude liquid fraction may then be subjected to a first chromatographic treatment to recover a first purified liquid fraction. The first chromatographic treatment may be carried out by using a gel-type strong acid cation exchange (SAC) resin. The SAC resin is a bead-like product which has a sulfonic acid group in the cross-linked styrene frame. The gel-type strong acid cation exchange (SAC) resin may be in Na+or K+ form. In one embodiment, the strong acid cation-exchange resin is in the Na+form. The strong acid cation-exchange resin in the Na+form may have a polystyrene structure where to divinyl benzene groups are crosslinked. The average particle size may be 280 pm. The SAC resin may have a cross-linking degree of 4 - 7 %. By the term "cross- inking degree of the resin" may refer to the divinylbenzene ( DVB) content in the resin which correlates with the internal pore diameter of the resin . In chromatographic treatment the resin is used as the separation material .

[0049] A first raffinate stream may be recovered from the first chromatographic treatment . The first raffinate stream may be taken to form the wood-derived carbohydrate composition as disclosed in the current disclosure .

[0050] The first purified liquid fraction may then be subj ected to evaporation before being subj ected to a second chromatographic treatment . Evaporating the first liquid fraction prior to the second chromatographic treatment has the added utility of keeping the s i ze of the chromatography column ( s ) on an economical level for industrial use . Reducing the amount of water going to the chromatographic treatment has the added utility of making the process more efficient for industrial use .

[0051] The first purified, and optionally evaporated, liquid fraction may then be subj ected to a second chromatographic treatment to recover a second purified liquid fraction . The second chromatographic treatment may be carried out by us ing a gel-type strong bas ic anion- exchange ( SBA) resin, which is composed of a matrix functionali zed with quaternary ammonium groups and which is in sulphate anion ( counterion) form . The strong basic anion-exchange resin is thus in sulphate anion form . The sulphate anions may be bonded through ionic bonding to the ammonium groups . The SBA resin in SO42- form may have a polystyrene structure whereto divinyl benzene groups are crosslinked . The average particle si ze may be 300 pm . The SBA res in may have a cross-linking degree of 4 - 8 % . The inventors surpris ingly have found out that the sulphate anions affected the sorption of the monosaccharides enabling the separation of xylose from the other monosaccharides . The sorption is governed by a ligand exchange type mechanism, in which the OH-groups in the monosaccharides form coordination complexes with the sulfate ions , and si ze exclusion . These interactions are different for each monosaccharide and thus result in their separation .

[0052] The matrix of the strong basic anion-exchange resin may be a divinylbenzene ( DVB) -based matrix . The matrix of the strong basic anion-exchange resin may be a styrene-divinylbenzene matrix or a methacrylate-divi- nylbenzene matrix . The inventors surprisingly found out that the use of the specific type of resin in the second chromatographic treatment has the added utility of efficiently increasing the xylose content to a level such that crystalli zation of the second purified liquid fraction can be carried out in an efficient manner while producing xylose crystals having a high xylose content . The use of a gel-type strong basic anion-exchange resin composed of a matrix functionali zed with quaternary ammonium groups and being in sulphate anion form has the added utility of reducing especially small molecular weight lignin from the fraction to a great extent . Being able to efficiently remove lignin affects especially the color of the produced xylose crystals as lignin tends to provide a brownish color . Further, the crystalli zation treatment following the second chromatographic treatment may be carried out with a rather short crys talli zation residence time as a result of the second chromatographic treatment providing an outcome with properties making the crystalli zation treatment efficient . Further, xylose may be separated from other sugars present in the first purified liquid fraction during the second chromatographic treatment resulting in a higher xylose content .

[0053] A second raffinate stream may be recovered from the second chromatographic treatment .

[0054] The first raffinate stream may be taken to form, either alone or in combination with the second raffinate stream, the wood-derived carbohydrate composition as disclosed in the current disclosure .

[0055] The cut-points for the fractionation in the first chromatographic treatment to recover the first raffinate stream can be determined from lignin yield determined based on the elution profiles obtained with a single column batchwise chromatography process . The cut-points for the fractionation in the second chromatographic treatment can be determined in similar manner using the removal level of the monosaccharides as the setpoint value for the fractionation . After the determination of the cut points , the production of the first and second raffinate streams can be carried out using a simulated moving bed ( SMB) chromatography, or with any variation of simulated moving bed chromatography with water as elution solution . Improved simulated moving bed chromatography ( I SMB) and sequential simulated moving bed chromatography ( SSMB) may be mentioned as examples of such variations . The flow rate through columns may be 1-4 bed volumes per hour .

[0056] After the chromatographic treatment , the wood- derived carbohydrate composition may be evaporated to a predetermined dry matter content .

[0057] The wood-derived carbohydrate composition has the added utility of comprising a high amount of xylose and especially a high amount of oligomeric xylose . The wood-based carbohydrate composition may thus find added utility in one being able to use the same as an animal feed additive .

[0058] The wood-derived carbohydrate composition has the added utility of being an easy-to-use liquid composition having a high concentration of carbohydrates . The high concentration of carbohydrates present in the composition increases the preservation of the carbohydrate composition resulting from the carbohydrates sucking up moisture from the composition whereby the preservability of the carbohydrate composition is increased . The wood- derived carbohydrate composition may thus not serve as a growth medium for harmful micro-organisms .

[0059] The wood-derived carbohydrate composition has the added utility of being a liquid composition that may be easy to process and transport . The wood-derived carbohydrate composition may be e . g . pumped from one tank to another and is al so easy to measure out for further use .

[0060] The wood-derived carbohydrate composition has the further added utility of not crystalli zing, not even when being stored in a freezer .

[0061] Further, the wood-derived carbohydrate composition has a pleasant odour .

[0062] EXAMPLES

[0063] Reference will now be made in detail to the embodiments of the present disclosure , an example of which is illustrated in the accompanying drawing .

[0064] The description below discloses some embodiments in such a detail that a person skilled in the art is able to utilize the wood-derived carbohydrate composition based on the disclosure . Not all steps of the embodiments are discussed in detail , as many of the steps will be obvious for the person skilled in the art based on this disclosure .

[0065] For reasons of simplicity, item numbers will be maintained in the following exemplary embodiments in the case of repeating components .

[0066] Example 1 - Producing a wood-based carbohydrate composition

[0067] In this example , a crude liquid fraction was provided as described above in the current disclosure . The crude liquid fraction had the following properties : total dry matter content : 50 . 0 weight-% soluble lignin content: 6.2 weight-% ICUMSA color value: 123 000 IU (pH 5.8)

[0068] The crude liquid fraction was subjected to a first chromatographic treatment followed by a second chromatographic treatment. A four column Improved Simulated Moving Bed (ISMB) process was used was used for both chromatographic treatments. The unit consisted of four columns where each had a volume 5.34 1. Diaion UBK530 resin in Na+form and AS501GC resin in SCg2-form were used as the separation materials in the first chromatographic treatment and second chromatographic treatment, respectively. The feed and eluent flowrates were 2 bed volumes per hour. One cycle of the ISMB process consists of four steps (1-4) between which the inlet and outlet points from the process were shifted in the direction of the liquid flow (simulation of the counter current movement of the liquid and separation material) . Each of the steps were divided into four sub-steps A-D as is presented in Fig. 1. In the first chromatographic treatment, the target fraction (the wood-derived carbohydrate composition) , i.e. the first raffinate stream (indicated as "Product 1-1" in the figures) was produced with the following sub-step durations: A = 146 s; B = 209 s; C = 356 s; D = 644 s. Thus, the total cycle time of the ISMB process was 90 min 20 s. The first raffinate stream was collected in sub-steps A and C while a first purified liquid fraction (indicated as "Product 1-2" in the figures) was collected in sub-step B. The first raffinate stream ("Product 1-1") can be concentrated separately to 63 weight-% total dry matter content by evaporation or it can be mixed with the second raffinate stream (indicated as "Product 2-1" in the figures) from the second chromatographic treatment before evaporation.

[0069] The first purified liquid fraction ("Product 1-2") was concentrated to 50 weight-% dry solids concentration and subsequently submitted to the second chromatographic treatment with the following sub-step durations: A = 150 s; B = 230 s; C = 345 s; D = 620 s. Thus, the total cycle time of the ISMB process was 89 min 40 s. A second raffinate stream ("Product 2-1") was collected in substeps A and C (first 80 s) , while a byproduct (indicated as "Product 2-2" in the figures) was collected in substep C (last 276 s) , and a further byproduct (indicated as "Product 2-3" in the figures) was collected in substep B. The second raffinate stream ("Product 2-1") may be taken as an intermediate product which can be combined with the first raffinate stream ("Product 1-1") and the formed mixture can be concentrated to 63.2 weight-% total dry matter content by evaporation ("Product 3" indicated in the figures is the combination of the first raffinate stream and the second raffinate stream) .

[0070] Table 1. Composition of the crude liquid fraction (indicated as "crude feed" in the figures) and the wood- derived carbohydrate composition

[0071] From the above results one can see that a carbohydrate composition with a high amount of xylose , and especially oligomeric xylose , may be obtained, while simultaneously exhibiting properties such as a soluble lignin content that beneficially affects e . g . the use of the carbohydrate composition as an animal feed additive .

[0072] It is obvious to a person skil led in the art that with the advancement of technology, the basic idea may be implemented in various ways . The embodiments are thus not limited to the examples described above ; instead they may vary within the scope of the claims .

[0073] The embodiments described hereinbefore may be used in any combination with each other . Several of the embodiments may be combined together to form a further embodiment . A wood-derived carbohydrate composition, the use , or an animal feed additive may comprise at least one of the embodiments described hereinbefore . It will be understood that the benef its and advantages described above may relate to one embodiment or may relate to several embodiments . The embodiments are not limited to those that solve any or all of the stated problems or those that have any or all of the stated benefits and advantages . It will further be understood that reference to ' an ' item refers to one or more of those items . The term "compri sing" is used in thi s specification to mean including the feature ( s ) or act ( s ) followed thereafter, without excluding the presence of one or more additional features or acts .

Claims

CLAIMS1. A wood-derived carbohydrate composition, wherein :- the carbohydrate composition comprises at least 40 weight-% of carbohydrates based on the total dry matter content of the carbohydrate composition,- at least 30 weight-% of the carbohydrates are xylose, and at least 50 weight-% of the xylose is oligomeric xylose.

2. The wood-derived carbohydrate composition of claim 1, wherein the carbohydrate composition comprises 40 - 90 weight-%, or 50 - 85 weight-%, or 60 - 80 weight-%, of carbohydrates based on the total dry matter content of the carbohydrate composition.

3. The wood-derived carbohydrate composition of any one of the preceding claims, wherein at least 35 weight-% of the carbohydrates are xylose.

4. The wood-derived carbohydrate composition of any one of the preceding claims, wherein at least 60 weight-%, or at least 70 weight-%, of the xylose is oligomeric xylose.

5. The wood-derived carbohydrate composition of any one of the preceding claims, wherein at most 50 weight-%, or at most 45 weight-%, or at most 40 weight- % , of the carbohydrates are C6 sugars.

6. The wood-derived carbohydrate composition of claim 5, wherein at least 20 weight-%, or at least 25 weight-%, or at least 30 weight-%, of the C6 sugars are mannose and / or galactose.

7. The wood-derived carbohydrate composition of any one of the preceding claims, wherein the carbohydrate composition comprises C5 sugars and wherein at least 1.0 weight-%, or at least 2.0 weight-%, or at least 3.0 weight-%, of the C5 sugars are arabinose.

8. The wood-derived carbohydrate composition of any one of the preceding claims, wherein thecarbohydrate composition comprises soluble lignin in a total amount of 10 - 24 weight-%, or 12 - 22 weight-%, or 14 - 20 weight-%, based on the total dry matter content of the carbohydrate composition.

9. The wood-derived carbohydrate composition of any one of the preceding claims, wherein the carbohydrate composition comprises sulphur in a total amount of 0.5 - 6.0 weight-%, or 1.0 - 4.0 weight-%, based on the total dry matter content of the carbohydrate composition.

10. The wood-derived carbohydrate composition of any one of the preceding claims, wherein the conductivity of a 30 % aqueous solution of the carbohydrate composition is 2 - 10 mS / cm, or 4 - 8 mS / cm, when determined according to SFS-EN 27888.

11. The wood-derived carbohydrate composition of any one of the preceding claims, wherein the ICUMSA color value of an aqueous solution of the carbohydrate composition is 250000 - 600000 IU, or 300000 - 550000 IU, or 350000 - 500000 IU.

12. The wood-derived carbohydrate composition of any one of the preceding claims, wherein the pH of the carbohydrate composition is 4 - 7, or 4.5 - 6.5, or 5 - 6.

13. The use of the wood-derived carbohydrate composition of any one of claims 1 - 12 for the production of biogas, ethanol, or animal feed additive.

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