Method for producing ethanol composition derived from lignocellulosic biomass

Abstract

To provide a method for producing an ethanol composition derived from lignocellulosic biomass.SOLUTION: A method for producing an ethanol composition from lignocellulosic biomass comprises the steps of: dry-grinding a lignocellulosic biomass raw material to prepare a finely ground material; surface-treating the finely ground material using a stone mill-type grinder; subjecting the surface-treated finely ground material to saccharification; and subjecting the saccharified material to ethanol fermentation. The finely ground material has a predetermined particle size distribution. The method enables production of an ethanol composition rich in desirable components.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present invention relates to a method for producing an ethanol composition using lignocellulosic biomass as a raw material.

Background Art

[0002] Currently, much of the industrial ethanol consumed in Japan is bioethanol produced from corn cobs and sugarcane, which are corn residues. Research and development on the production of ethanol from lignocellulosic biomass are also ongoing, but one of the challenges is to achieve both improved efficiency of saccharification, which converts cellulose contained in lignocellulosic biomass into sugars that can be utilized by microorganisms for alcohol fermentation, and economic viability.

[0003] The main components of lignocellulosic biomass are cellulose, hemicellulose, and lignin. Lignocellulosic biomass contains lignocellulose-structured wood fibers in which cellulose fibers are bundled and aggregated by hemicellulose and lignin, and is also called lignocellulosic biomass. The lignocellulose structure of wood fibers is very strong and chemically stable, and it is difficult to perform enzymatic saccharification treatment of cellulose or hemicellulose as it is. Therefore, as a pretreatment, mechanical grinding treatment, chemical treatment using acids or alkalis, physicochemical treatment using high-temperature and high-pressure water, etc. are performed.

[0004] For example, Patent Document 1 discloses a method of subjecting a lignocellulose-containing raw material to dilute sulfuric acid treatment and lime treatment and then performing enzymatic hydrolysis treatment. Patent Document 2 discloses a method of subjecting lignocellulosic biomass to pressurized hot water treatment and mechanical grinding treatment and then performing saccharification treatment with an enzyme. Patent Document 3 discloses a method of pulverizing the above-ground part of a plant body, which is a lignocellulosic biomass raw material, performing alkali treatment and neutralization treatment, and then performing saccharification treatment with an enzyme. Furthermore, Patent Document 4 discloses a method of producing an alcoholic beverage from tree materials, in which the tree materials are pulverized to 5 μm or less by wet grinding to form a slurry, which is then saccharified and subjected to alcohol fermentation.

Prior Art Documents

Patent Document

[0005]

Patent Document 1

Patent Document 2

Patent Document 3

Patent Document 4

Summary of the Invention

[0006] The inventors have found that an ethanol composition can be produced from lignocellulosic biomass without requiring chemical treatment or physicochemical treatment by dry-milling a lignocellulosic biomass raw material and further surface-treating the particles obtained by the fine milling.

[0007] The present disclosure provides the following inventions. Item 1. A method for producing an ethanol composition from a lignocellulosic biomass, comprising a step of dry-milling a lignocellulosic biomass raw material to prepare a fine powder, a step of surface-treating the fine powder using a stone mill grinder, a step of saccharifying the surface-treated fine powder, and a step of ethanol-fermenting the saccharified product, wherein the fine powder after the surface treatment has d(10) of 4 to 15 μm, d(50) of 15 to 50 μm, and d(90) of 60 to 200 μm in the volume-based cumulative particle size distribution measured by the laser diffraction method. Item 2. The method according to Item 1, wherein the dry-milling is performed using a jet mill. Item 3. The method according to Item 1 or 2, wherein the surface treatment is performed using an aqueous suspension of the fine powder. Item 4. The method according to any one of Items 1 to 3, wherein the saccharification treatment and the ethanol fermentation are performed in parallel. Item 5. The method according to any one of Items 1 to 4, further comprising a step of distilling the fermented product or its supernatant after the ethanol fermentation to recover a distillate. Item 6. A fine powder of lignocellulosic biomass for subjecting to saccharification treatment, wherein the particle surface is defibrated, and d(10) in the volume-based cumulative particle size distribution measured by the laser diffraction method is 4 to 15 μm, d(50) is 15 to 50 μm, and d(90) is 60 to 200 μm.

[0008] According to the present invention, since chemical treatment or physicochemical treatment of the lignocellulosic biomass raw material as a pretreatment for saccharification is not required, there is no concern about overdecomposition of sugar, and energy consumption is also low. Therefore, an ethanol composition can be produced more efficiently and at a lower cost. Further, since the particle diameter of the fine powder for saccharification is large, separation from the fermentation residue is easy, and a high recovery rate can be realized by a simple operation. Furthermore, since the specific surface area of the pulverized product is small, combined with the fact that there is no chemical treatment or physicochemical treatment, loss of components derived from the raw material is suppressed, and an ethanol composition rich in favorable components can be produced.

Brief Description of the Drawings

[0009]

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Modes for Carrying Out the Invention

[0010] The following description may be based on representative embodiments or specific examples, but the present invention is not limited to such embodiments or specific examples. The upper and lower limit values of each numerical range shown in this specification can be arbitrarily combined. Also, a numerical range represented by "~" or "-" in this specification means a range including the numerical values at both ends thereof as the upper limit value and the lower limit value unless otherwise specified.

[0011] The present disclosure provides a method for producing an ethanol composition from lignocellulosic biomass, which includes a step of dry-grinding a lignocellulosic biomass raw material to prepare a fine ground material, a step of surface-treating the fine ground material using a stone mill, a step of saccharifying the surface-treated fine ground material, and a step of ethanol-fermenting the saccharified product, wherein the fine ground material after the surface treatment has a d(10) of 4 to 15 μm, a d(50) of 15 to 50 μm, and a d(90) of 60 to 200 μm in the volume-based cumulative particle size distribution measured by the laser diffraction method.

[0012] In the present invention, the lignocellulosic biomass raw material is a material containing lignocellulosic-structured wood fibers, and examples thereof include parts such as the trunk, bark, branches, roots, leaves, and stems of trees. Examples of the lignocellulosic biomass raw material include timber, unused wood generated during thinning or final felling, bark, backboards, sawdust, and other residues from sawmills, and construction-generated wood generated at the construction sites of civil engineering works or when demolishing wooden buildings can be used.

[0013] There are no particular restrictions on the types of trees used as lignocellulosic biomass raw materials, and they can be appropriately selected according to the desired ethanol composition. The trees can be broad-leaved trees or coniferous trees. For example, birches (plants of the genus Betula in the family Betulaceae; examples include Japanese white birch, dahurian birch, and udi birch), maples (plants of the genus Acer in the family Aceraceae; examples include maple, large-leaved maple, dwarf maple, kekka maple, and usuge maple), Cryptomeria japonica (a native species of Japan in the genus Cryptomeria of the family Taxodiaceae, growing naturally in Hokkaido, Honshu, Shikoku, Kyushu, Yakushima, etc., and also including T. plicata basswood, etc.), willows (plants of the genus Salix in the family Salicaceae; weeping willow, white willow, pussy willow, poplar, etc.), myricas (myrica gale in the family Myricaceae, such as yachiyanaagi), pines (Pinus, such as hokkaido pine, red pine, black pine, goyomatsu, dwarf komatsu, high pine, ryukyu pine, and Korean pine), phellodendrons (Phellodendron amurense in the family Rutaceae, such as amur cork tree, yellow cork tree, yellow bark, and cork tree), etc., but are not limited thereto.

[0014] [Fine pulverization step] The production method of the present invention includes a step of dry pulverizing a lignocellulosic biomass raw material to prepare a fine pulverized product (referred to as the fine pulverization step).

[0015] The lignocellulosic biomass raw material used in the fine pulverization process may be in a dry state and of a size that can be dry-pulverized. In the case of a lignocellulosic biomass raw material with a large size, as a pretreatment before dry pulverization, it is pulverized (coarse pulverization or medium pulverization) to a size that can be dry-pulverized and then used. The size of the lignocellulosic biomass raw material to be subjected to dry pulverization has a maximum diameter of, for example, about 0.5 mm to 10 mm, preferably 0.5 mm to 5 mm, and more preferably 0.5 mm to 3 mm. The pulverization of the lignocellulosic biomass raw material as a pretreatment can be carried out by appropriately adjusting the pulverization conditions using a commercially available pulverizer (coarse pulverizer or medium pulverizer) such as a sawdust manufacturing machine, a roll crusher, a cutter mill, or other machines capable of pulverizing wood so that the size of the pulverized product is generally within the above range.

[0016] The lignocellulosic biomass raw material is pulverized as a pre-treatment as described above if necessary, and then further pulverized finely by dry pulverization to obtain a fine pulverized product. Dry pulverization is pulverization performed in air or other gases. Examples of pulverizers capable of dry pulverization include impact pulverizers that pulverize the material to be pulverized by applying impact with a striking member, pins, blades, etc. (e.g., hammer mills, pin mills, bead mills, etc.), jet mills (airflow impact pulverizers) that generate a jet airflow by ejecting high-pressure air or gas and cause the materials to be pulverized to collide with each other. In the present invention, any dry pulverizer capable of finely pulverizing the lignocellulosic biomass raw material can be used without limitation. In particular, those having a screen or an airflow classification mechanism capable of recovering a finely pulverized product of a desired size are preferred. Examples of such a pulverizer include the airflow impact pulverizing and classifying device "Porvozyme" manufactured by Nara Machinery Co., Ltd. The airflow impact pulverizing and classifying device is a dry airflow impact pulverizer combined with a classification section, and it is possible to finish the particle size of millimeter-sized raw materials up to the fine pulverization region by a jet mill. By combining a pulverization section with high pulverization efficiency and a classification section with a separate power source, it is possible to greatly increase the adjustment range of the air volume, and it is possible to thoroughly improve the excellent product temperature control of the raw material and the pulverization efficiency of the biomass. Also, the processing capacity per unit time is advantageous among dry atomizing devices. It has the characteristics of both airflow classification and impact pulverization, and has the advantage of less heat generation during pulverization.

[0017] The dry pulverization of the lignocellulosic biomass raw material can be carried out by appropriately adjusting the pulverization conditions so that the lignocellulosic biomass raw material becomes a size that allows subsequent surface treatment with a stone mortar mill.

[0018] In certain embodiments, the finely ground product of the lignocellulosic biomass raw material prepared by dry grinding has a d(10) of 4 to 15 μm, a d(50) of 15 to 50 μm, and a d(90) of 60 to 200 μm in the volume-based cumulative particle size distribution measured by the laser diffraction method. In certain embodiments, the finely ground product of the lignocellulosic biomass raw material prepared by dry grinding has a mode diameter of 15 to 70 μm in the volume-based measurement by the laser diffraction method. In certain embodiments, the finely ground product of the lignocellulosic biomass raw material prepared by dry grinding has a volume average diameter of 20 to 70 μm in the volume-based measurement by the laser diffraction method.

[0019] In certain embodiments, the finely ground product of the lignocellulosic biomass raw material prepared by dry grinding has a mode diameter of 15 to 70 μm in the volume-based measurement by the laser diffraction method, a d(10) of 4 to 15 μm, a d(50) of 15 to 50 μm, and a d(90) of 60 to 200 μm in the volume-based cumulative particle size distribution. In certain embodiments, the finely ground product of the lignocellulosic biomass raw material prepared by dry grinding has a volume average diameter of 20 to 70 μm in the volume-based measurement by the laser diffraction method, a d(10) of 4 to 15 μm, a d(50) of 15 to 50 μm, and a d(90) of 60 to 200 μm in the volume-based cumulative particle size distribution.

[0020] In the present invention, the particle size distribution of the finely ground product is measured by the laser diffraction method. The measurement can be performed using a commercially available particle size distribution measuring device, for example, "Microtrac" (trade name) of MicrotracBEL, "Mastersizer" (trade name) of Malvern Panalytical, etc. When the particles contained in the measured finely ground product are accumulated in ascending order of particle size, the particle size at the point where the cumulative volume becomes 10% of the total volume is d(10), the particle size at the point where the cumulative volume becomes 50% of the total volume is d(50), and the particle size at the point where the cumulative volume becomes 90% of the total volume is d(90). Also, the particle size at which the appearance ratio is the largest in the volume-based frequency distribution is the mode diameter, and the arithmetic mean value of the volume-based particle sizes is the volume average diameter.

[0021] The finely ground product of the lignocellulosic biomass raw material prepared by dry grinding may have a d(10) of 4 to 15 μm, preferably 5 to 15 μm, more preferably 6 to 12 μm, a d(50) of 15 to 50 μm, preferably 15 to 45 μm, more preferably 20 to 40 μm, and a d(90) of 60 to 200 μm, preferably 65 to 150, more preferably 70 to 120 μm or less.

[0022] The finely ground product of the lignocellulosic biomass raw material prepared by dry grinding may have a mode diameter of 15 to 70 μm, preferably 20 to 70 μm, more preferably 20 to 50 μm.

[0023] The finely ground product of the lignocellulosic biomass raw material prepared by dry grinding may have a volume average diameter of 20 to 70 μm, preferably 25 to 60 μm, more preferably 30 to 55 μm.

[0024] [Surface treatment step] The production method of the present invention includes a step of surface-treating the finely ground product prepared in the fine grinding step (referred to as the surface treatment step) using a stone mill. The surface treatment in this step means a treatment that does not cause volume grinding of the particles as much as possible and breaks and defibrates the lignocellulose structure on the particle surface by friction.

[0025] In certain embodiments, the finely ground product after surface treatment has a d(10) of 4 to 15 μm, a d(50) of 15 to 50 μm, and a d(90) of 60 to 200 μm in the volume-based cumulative particle size distribution measured by the laser diffraction method. In certain embodiments, the finely ground product after surface treatment has a mode diameter of 15 to 70 μm in the volume-based measurement by the laser diffraction method. In certain embodiments, the finely ground product after surface treatment has a volume average diameter of 20 to 70 μm measured by the laser diffraction method.

[0026] In certain embodiments, the volume-based mode diameter of the finely ground material after surface treatment, as measured by the laser diffraction method, is 15 to 70 μm, d(10) in the volume-based cumulative particle size distribution is 4 to 15 μm, d(50) is 15 to 50 μm, and d(90) is 60 to 200 μm. In certain embodiments, the volume average diameter of the finely ground material after surface treatment, as measured by the laser diffraction method, is 20 to 70 μm, d(10) in the volume-based cumulative particle size distribution is 4 to 15 μm, d(50) is 15 to 50 μm, and d(90) is 60 to 200 μm.

[0027] The finely ground material after surface treatment can have d(10) of 4 to 15 μm, preferably 5 to 15 μm, more preferably 6 to 12 μm, d(50) of 15 to 50 μm, preferably 15 to 45 μm, more preferably 20 to 40 μm, and d(90) of 60 to 200 μm, preferably 65 to 150, more preferably 70 to 120 μm or less.

[0028] The finely ground material after surface treatment can have a mode diameter of 15 to 70 μm, preferably 20 to 70 μm, more preferably 20 to 50 μm.

[0029] The finely ground material after surface treatment can have a volume average diameter of 20 to 70 μm, preferably 25 to 60 μm, more preferably 30 to 55 μm.

[0030] The surface treatment is performed by using a mortar mill on a liquid in which the finely ground material is suspended in an aqueous medium. The aqueous medium can be any water such as pure water, distilled water, sterilized water, tap water, well water, spring water, etc., and may also contain a pH adjuster or other additives. The aqueous medium can be used in an amount about 1 to 20 times, preferably 2 to 15 times, more preferably 5 to 10 times the amount of the finely ground material in terms of weight conversion.

[0031] A mortar crusher is a crusher that crushes by passing the material to be crushed through the gap between two opposing grindstones. Examples thereof include the "Super Mascoloider" (trade name) manufactured by Masayuki Sangyo Co., Ltd. The surface treatment of the finely pulverized material can be carried out by appropriately adjusting the operating conditions of the mortar crusher, such as the clearance between the grindstones, the rotational speed of the grindstones, the number of repeated treatment passes (number of passes), etc. The operating conditions are, for example, grinder diameter: 4 to 8 inches, clearance: 0.05 mm or less, preferably 0.01 mm or less, rotational speed: 300 to 2500 rpm, preferably 500 to 2000 rpm, load current: 3 to 5 A, number of passes: 1 or more, preferably 1 to 4 times.

[0032] By the surface treatment, the finely pulverized material of the lignocellulosic biomass raw material is in a state where the lignocellulose structure on the particle surface is destroyed and defibrated. As a result, the cellulose and hemicellulose of the particles are efficiently exposed in the aqueous medium, and the saccharification efficiency can be improved. The surface treatment can be confirmed by observing the particle surface of the finely pulverized material using a scanning electron microscope or other optical means.

[0033] Also, the surface treatment also has the effect of reducing the viscosity of the finely pulverized material suspension. The reduction in the viscosity of the finely pulverized material enhances the operability in the subsequent saccharification process and fermentation process, and also facilitates the solid-liquid separation after fermentation, thereby improving the production efficiency of the ethanol composition.

[0034] [Saccharification process] The manufacturing method of the present invention includes a step of saccharifying the surface-treated pulverized material (referred to as the saccharification step). The saccharification treatment can be performed by adding a saccharifying enzyme to an aqueous medium suspension of the surface-treated pulverized material. The saccharifying enzyme may have cellulase activity, and preferably further has hemicellulase activity. As the saccharifying enzyme, a commercially available enzyme preparation may be used, an isolated and purified enzyme may be used, or a culture solution or extract of a microorganism that produces the saccharifying enzyme may be used. Examples of preferred saccharifying enzymes include commercially available cellulase preparations such as "Acremocellulase KM" and "Cellulase TP5-Kyowa" (both are trade names) of Kyowa Chemical Industry Co., Ltd., "Meicellase" (trade name) of Meiji Seika Pharma Co., Ltd., and "Sclarase C" (trade name) of Mitsubishi Chemical Corporation.

[0035] For the saccharification treatment, the pulverized material suspension after surface treatment may be used as it is, or an aqueous medium may be added to the pulverized material suspension, or solid-liquid separation may be performed to remove the aqueous medium. Further, a pH adjuster or other additives may be added to the pulverized material suspension.

[0036] The saccharification treatment can be carried out by adjusting reaction conditions such as the amount of enzyme added, reaction time, temperature, pH, etc. so as to be suitable for the saccharifying enzyme used. When using a commercially available cellulase preparation, it may be carried out according to the protocol recommended by the manufacturer. In one embodiment, the saccharification treatment is carried out by adding an amount of saccharifying enzyme corresponding to 5 to 10% by mass of the pulverized material to an aqueous medium suspension having a pH of 4 to 7 containing 1 to 50% by mass, preferably 2 to 30% by mass, more preferably 5 to 20% by mass of the pulverized material, and reacting while stirring at a temperature of 30°C to 60°C.

[0037] By saccharification treatment, the finely pulverized material of lignocellulosic biomass raw material is hydrolyzed. When saccharification proceeds completely, cellulose is finally converted into glucose, and hemicellulose is finally converted into hemicellulose constituent sugars such as xylose and mannose. In the saccharification process, it is not essential for saccharification to proceed completely, and it is sufficient to produce at least the amount of sugars that can be assimilated by the microorganisms used in the subsequent fermentation process, which is necessary for the start of fermentation.

[0038] [Fermentation process] The production method of the present invention includes a step of subjecting the saccharified product to ethanol fermentation (referred to as the fermentation step). The saccharified product is obtained by saccharifying the finely pulverized material of the surface-treated lignocellulosic biomass raw material and contains sugars such as monosaccharides and oligosaccharides that can be assimilated by the microorganisms that perform ethanol fermentation.

[0039] Ethanol fermentation is carried out by adding a microorganism capable of producing ethanol from sugars, preferably yeast used in brewing or bread making, to the saccharified product. As yeast, it is preferable to use baker's yeast or brewing yeast. For example, various strains such as dry yeast for bread making, "Kyo kai yeast" (registered trademark), which is brewing yeast distributed by the Japan Brewing Association, a public interest incorporated foundation, and preserved strains of the Microbial Bank can be used.

[0040] For ethanol fermentation, the finely pulverized material suspension after the saccharification step can be used as it is, but an aqueous medium may be added, or a pH adjuster or other additives may be added.

[0041] Ethanol fermentation can be carried out by adjusting, for example, the amount of microorganisms added, fermentation time, temperature, pH, aeration amount, stirring, etc., so as to be conditions suitable for the microorganisms used. Methods for performing ethanol fermentation using microorganisms from the saccharified product of lignocellulosic biomass raw materials are known to those skilled in the art, and those known methods can be used for ethanol fermentation in the production method of the present invention.

[0042] Ethanol fermentation may be so-called simultaneous saccharification and fermentation (SSF) that is carried out in parallel with saccharification. At this time, the fermentation process will be carried out in parallel with the saccharification process. SSF may be carried out by simultaneously adding a saccharifying enzyme and a microorganism for ethanol fermentation to a suspension of surface-treated finely ground material. However, it is preferable to perform the saccharification treatment first under conditions suitable for saccharification, and after changing the conditions to be suitable for ethanol fermentation as necessary without performing a special operation to stop the saccharification, add the microorganism and carry out ethanol fermentation. In one embodiment, an aqueous medium suspension having a pH of 4 to 7 containing 1 to 50% by mass, preferably 2 to 30% by mass, more preferably 5 to 20% by mass of the finely ground material is saccharified by stirring at 30°C to 60°C for 12 to 60 hours, and then 0.5 to 5% by mass of dry yeast is added to the suspension, and SSF is carried out at 40°C to 50°C for 3 to 10 days, whereby the saccharification process and the fermentation process can be carried out in parallel.

[0043] In the production method of the present invention, the surface treatment step, the saccharification step, and the fermentation step do not require a separation and concentration treatment such as solid-liquid separation between the steps, and can be continuously carried out while the finely ground material suspension remains in a state.

[0044] Further, in the production method of the present invention, each of the surface treatment step, the saccharification step, and the fermentation step can be carried out without adding an additive such as a pH adjuster. At this time, the materials used until the end of fermentation are only a lignocellulosic biomass raw material, water, a saccharifying enzyme, and a microorganism capable of producing ethanol from saccharides.

[0045] The fermented product obtained by ethanol fermentation contains ethanol. Although the ethanol content of the fermented product varies depending on the type and part of the lignocellulosic biomass raw material, the conditions of the fine grinding step, the saccharification step, and the fermentation step, etc., it may contain 1 to 20%, preferably 5 to 20%, more preferably 10 to 20% ethanol.

[0046] The fermented product may be used directly as an ethanol composition, but it is preferable to use the supernatant obtained by solid-liquid separation to remove the solid fermentation residue, and the distillate obtained by distilling the fermented product or its supernatant as the ethanol composition. Solid-liquid separation can be carried out by separation means such as filtration, centrifugation, and decantation.

[0047] In the prior art that performs mechanical crushing as a pretreatment for saccharification, in order to achieve sufficient saccharification, the lignocellulosic biomass raw material is pulverized to single micron size. Therefore, the raw material after pulverization, its saccharified product, and the fermented product are in a highly viscous slurry state, and solid-liquid separation by filtration or decantation is difficult. On the other hand, in the production method of the present invention, the particle size of the pulverized product is larger than that of the prior art, and the viscosity can be reduced by surface treatment. Therefore, the raw material after pulverization, its saccharified product, and the fermented product do not become slurried or are in a low-viscosity slurry state, and have the advantage that solid-liquid separation by filtration or decantation is easy.

[0048] [Distillation step] The production method of the present invention may further include a step of distilling the fermented product after ethanol fermentation or its supernatant to recover the distillate. Distillation may be performed on the fermented product, but it is preferable to perform distillation on the supernatant obtained by solid-liquid separation of the fermented product. The distillation may be simple distillation or continuous distillation, and can be performed once or multiple times. Also, the distillation may be atmospheric distillation or vacuum distillation, and vacuum distillation is preferable.

[0049] By distillation, an ethanol composition with a higher ethanol concentration and a higher concentration of aroma components derived from the raw material than the original fermented product can be prepared. The ethanol composition containing a high concentration of ethanol can be used as a hygienic ethanol having a preferable fragrance or a fragrance raw material for the purpose of disinfection, sterilization, or cleaning.

[0050] The ethanol composition obtained by the production method of the present invention may be subjected to a sterilization treatment at any stage as long as each step is not hindered. Examples of the sterilization treatment include filtration, heat sterilization, and the like.

[0051] The ethanol composition obtained by the production method of the present invention is a complex composition containing, in addition to ethanol, various components derived from lignocellulosic biomass raw materials, metabolites of these components by yeast, and components generated by chemical changes in each step. The ethanol composition contains aroma components such as terpenes that can impart a favorable aroma to the composition. Since the aroma components can vary depending on the type and part of the lignocellulosic biomass used as the raw material, it is possible to produce ethanol compositions having various aroma components by appropriately selecting the raw material.

[0052] Hereinafter, the present invention will be specifically described with reference to examples. However, these examples are for helping the understanding of the present invention and do not limit the technical scope of the present invention.

Examples

[0053] [Production of Ethanol Composition Using Magnolia obovata as Raw Material in Example 1] (1) Preparation of Fine Powder The logs of Magnolia obovata without bark were dried in a constant temperature and humidity chamber (Espec) at a temperature of 25°C and a humidity of 20% for 1 week, then cut into chips, and further pulverized with a rotary crusher (Sanjo Industry NR-04A) for 30 seconds, and passed through a sieve machine (mesh 50) to collect the pulverized material with a diameter smaller than 300 μm.

[0054] Using an air jet impact pulverization and classification device (Nara Machinery Co., Ltd., PorvoGene PG-3), the pulverization rotation speed: 8000 min -1 , the pulverization current value: 15 - 17 A, the classifier rotation speed: 6000 min -1 , the classification current value: 1 - 1.5 A, the suction air volume: 4 m 3 / min, and the raw material supply speed: 3 kg / hr, the above pulverized material was dry-pulverized to collect the fine powder.

[0055] (2) Surface Treatment A suspension obtained by mixing 2.5 kg of the finely ground product prepared in (1) and 12.5 L of water (weight ratio 1:5) was processed using a mortar mill (Masuko Sangyo Co., Ltd., Super Mass Colloid Mill MKCA6-3INV) under the conditions of a clearance of 0.01 mm, a rotation speed of 1000 rpm, and a current value of 3.7 A (provisional test conditions). The passed suspension was further processed under the conditions of a clearance <0.01 mm, a rotation speed of 1500 rpm, and a current value of 3.9 A (this test condition), and the passed finely ground product suspension was recovered.

[0056] For the finely ground product before surface treatment, after surface treatment (provisional test), and after surface treatment (this test), the particle size distribution was measured using a laser diffraction scattering type particle size distribution measuring device MT-3300EXII (manufactured by MicrotracBEL Co., Ltd.). The particle size distribution is shown in Figure 1, and the SEM (JEOL-IT300LV) photographed image of the finely ground product is shown in Figure 2. The surface treatment did not significantly change the particle diameter and particle size distribution of the finely ground product. For any of the finely ground products, d(10) was in the range of 6 - 9 μm, d(50) was in the range of 20 - 30 μm, and d(90) was in the range of 70 - 100 μm. Also, the mode diameter was in the range of 20 - 30 μm, and the volume average particle diameter (MV) was in the range of 30 - 50 μm. Also, the surface layer of the particles after surface treatment was destroyed.

[0057] (3) Saccharification treatment and fermentation treatment The total amount of the finely ground product suspension obtained in (2) was transferred to a 30 L incubator, 300 g of Acremon cellulase KM (Kyowa Chemical Industry Co., Ltd.), an enzyme preparation having cellulase activity and hemicellulase activity, was added, and saccharification treatment was carried out by incubating with stirring at 50°C. Two days after the start of the treatment, the temperature of the fermentation vessel was lowered to 45°C, 100 g of dry yeast (Oriental Yeast) was added, and incubation was further carried out for 5.5 days to perform parallel co-fermentation. After the fermentation was completed, the culture was subjected to solid-liquid separation by filtration using a filter bag (medium mesh), and 9.2 L of culture supernatant was recovered.

[0058] In the above-mentioned saccharification treatment and fermentation treatment steps, the pH, DO, and sugar content were measured for the liquid at the start of the saccharification treatment (before adding the saccharifying enzyme), the liquid at the end of the saccharification treatment (before adding dry yeast), and the culture supernatant after fermentation. The results are shown in Table 1. [Table 1]

[0059] The ethanol concentration of the culture supernatant after fermentation was measured using a boiling-point type alcohol meter. The ethanol concentration of the culture supernatant was 13.5 mg / mL.

[0060] (4) Distillation The total amount of the culture supernatant obtained in (3) was distilled using a continuous distillation apparatus. Distillation was carried out at a still temperature of 101 °C and a partial condenser temperature of 28 °C. Distillation was performed at a liquid surface temperature of 75 °C and a pressure of 315 hPa, or at a liquid surface temperature of 50 °C and a pressure of 50 hPa. The distillate recovered in the partial condenser was re-distilled twice at a liquid surface temperature of 75 °C and a pressure of 315 hPa. Finally, 20 mL of the distillate was recovered, and its ethanol concentration was measured by high performance liquid chromatography, and it was confirmed that it was 90% or more.

[0061] (5) Component analysis The final distillate obtained in (4) was analyzed using GC-MS under the following conditions to measure the aroma components. Sample preparation method: The final distillate was subjected to solid-phase column extraction using Sigma-Aldrich carboxen / polydimethylsiloxane (CAR / PDMS) 80 μm and then used for GC-MS. Chromatographic separation was carried out using a Restek Rtx-5MS column and an Agilent DB-WAX column, and identification was performed by comparing the retention index with the spectral library. The final analysis conditions are shown below. Equipment used: Gas chromatograph mass spectrometer (JEOL JMS-T100GCV) Analysis conditions Column 1: DB-5MS 30M × 0.25 mm × 0.25 μm Column 2: DB-WAX 30M × 0.25mm × 0.25μm Carrier gas: He 1.5mL / min Inlet temperature: 280°C Temperature program (heating method): After holding at 35°C for 3 minutes initially, the temperature was raised to 200°C at 4°C / min. Thereafter, the temperature was raised to 250°C at 25°C / min. Common conditions Splitless injection Transfer line temperature: 250°C Detector 2000V Electron ionization (EI) mode: 70eV Ion source temperature 250°C Mass range 10 - 500.

[0062] The total ion chromatogram when using Column 1 is shown in Figure 3A, and the retention time and component name for each peak are shown in Table 2-1. Also, the total ion chromatogram when using Column 2 is shown in Figure 3B, and the retention time and component name for each peak are shown in Table 2-2. As wood-derived aroma components, many low-boiling terpenes such as β-myrcene, α-terpinene, limonene, and cymene were detected. In the column, carboxylic acid, eucalyptol, borneol, geraniol, and oidesmol were also detected with high recovery rates. Even in trace amounts, these have a great impact on the overall aroma. [Table 2-1] [Table 2-2]

[0063] [Example 2 Production of Ethanol Composition Using Shirakamba as Raw Material] (1) Preparation and Surface Treatment of Fine Powder The shirakamba logs without bark were pulverized into fine powder in the same manner as in (1) of Example 1. A suspension was prepared by mixing 5 kg of the pulverized material and 25 L of water (weight ratio 1:5), and the suspension was processed using a stone mortar grinder (Masuko Sangyo Co., Ltd., Super Mass Colloid MKCA6-3INV) under the conditions of a clearance of 0.1 mm and a rotational speed of 1500 rpm (temporary test conditions). The passed suspension was further processed under the conditions of a clearance <0.001 mm, a rotational speed of 1500 - 2000 rpm, and a current value of 4.5 A (this test condition), and the passed pulverized material suspension was collected.

[0064] For the pulverized material before surface treatment, after surface treatment (temporary test), and after surface treatment (this test), the particle size distribution was measured using a laser diffraction particle size distribution analyzer MT-3300EXII (manufactured by Microtrac Bel Co., Ltd.). The particle size distribution is shown in Figure 4, and the SEM (JEOL-IT300LV) photographed images of the pulverized material are shown in Figure 5. The surface treatment did not significantly change the particle diameter and particle size distribution of the pulverized material. For any of the pulverized materials, d(10) was in the range of 9 - 11 μm, d(50) was in the range of 30 - 40 μm, and d(90) was in the range of 90 - 110 μm. Also, the mode diameter was in the range of 30 - 40 μm, and the volume average particle diameter (MV) was in the range of 45 - 55 μm. Moreover, the surface layer of the particles after surface treatment was destroyed. (2) Saccharification treatment and fermentation treatment The entire amount of the pulverized material suspension obtained in (1) was transferred to a 30 L incubator, 300 g of Acremon cellulase KM (Kyowa Chemical Industry Co., Ltd.) was added, and saccharification treatment was carried out by incubating with stirring at 50°C. Two days after the start of the treatment, the temperature of the fermentation vessel was lowered to 40°C, 100 g of dry yeast (Oriental Yeast) was added, and incubation was continued for another 6 days to perform parallel fermentation. After the fermentation was completed, the culture was subjected to solid-liquid separation by filtration using a cheesecloth (medium mesh), and 16 L of the culture supernatant was recovered.

[0065] In the above saccharification treatment and fermentation treatment processes, the pH, DO, and sugar content were measured for the liquid at the start of the saccharification treatment (before adding saccharifying enzyme), the liquid at the end of the saccharification treatment (before adding dry yeast), and the culture supernatant after fermentation. The results are shown in Table 3.

Table 3

[0066] The ethanol concentration of the culture supernatant after fermentation was measured by high performance liquid chromatography. The ethanol concentration of the culture supernatant was 15.8 mg / mL. (3) Distillation The total amount of the culture supernatant obtained in (2) was distilled using a continuous distiller at a still temperature of 101 °C and a partial condenser temperature of 28 °C. The distillation was carried out at a liquid surface temperature of 75 °C and an atmospheric pressure of 315 hPa, and the distillate recovered by the partial condenser was redistilled once at a liquid surface temperature of 75 °C and an atmospheric pressure of 315 hPa. Finally, 20 mL of the distillate was recovered, and its ethanol concentration was measured by high performance liquid chromatography, and it was confirmed that it was 90% or more.

[0067] (5) Component analysis The final distillate obtained in (4) was analyzed using GC-MS in the same manner as (5) of Example 1 to measure the aroma components. The total ion chromatogram when using Column 1 is shown in Fig. 6A, and the retention time and component name for each peak are shown in Table 4-1. Also, the total ion chromatogram when using Column 2 is shown in Fig. 6B, and the retention time and component name for each peak are shown in Table 4-2. In addition to components such as 1-hexanol known to be produced during ethanol fermentation, components such as terpenes (α-pinene, limonene, linalool, bergamotene, santalene) presumed to be derived from the raw material, shirakamba, were detected. [Table 4-1] [Table 4-2]

[0068] [Example 3 Production of Ethanol Composition Using Cryptomeria as Raw Material] In the same manner as in Example 1 or 2, Cryptomeria japonica was used as a raw material for fine pulverization, saccharification treatment, fermentation treatment, and distillation to obtain a distillate with an ethanol concentration of 90% or more, and the aroma components were measured by GC-MS analysis. The total ion chromatogram when Column 1 was used is shown in Fig. 7A, and the retention time and component name for each peak are shown in Table 5-1. Also, the total ion chromatogram when Column 2 was used is shown in Fig. 7B, and the retention time and component name for each peak are shown in Table 5-2. As wood-derived aroma components, many low-boiling terpenes such as β-myrcene, α-terpinene, limonene, and cymene were detected. Carboxylic acids, eucalyptol, borneol, geraniol, and γ-eudesmol were also detected at high recovery rates. Even in trace amounts, these have a great influence on the overall aroma. [Table 5-1] [Table 5-2]

[0069] [Example 4 Production of Ethanol Composition Using Larix kaempferi as Raw Material] In the same manner as in Example 1 or 2, Larix kaempferi was used as a raw material for fine pulverization, saccharification treatment, fermentation treatment, and distillation to obtain a distillate with an ethanol concentration of 90% or more, and the aroma components were measured by GC-MS analysis. The total ion chromatogram when Column 1 was used is shown in Fig. 8A, and the retention time and component name for each peak are shown in Table 6-1. Also, the total ion chromatogram when Column 2 was used is shown in Fig. 8B, and the retention time and component name for each peak are shown in Table 6-2. [Table 6-1] [Table 6-2]

[0070] [Example 5 Production of Ethanol Composition Using Salix babylonica as Raw Material] In the same manner as in Example 1 or 2, willows were used as raw materials and subjected to fine pulverization, saccharification treatment, fermentation treatment, and distillation to obtain a distillate with an ethanol concentration of 90% or more, and the aroma components were measured by GC-MS analysis. The total ion chromatogram when Column 1 was used is shown in Fig. 9A, and the retention time and component name for each peak are shown in Table 7-1. Also, the total ion chromatogram when Column 2 was used is shown in Fig. 9B, and the retention time and component name for each peak are shown in Table 7-2. [Table 7-1] [Table 7-2]

[0071] [Test Example 1] The logs of Shirakamba were finely pulverized in the same manner as in (1) of Example 1. The pulverized product and water were mixed at a weight ratio of 1:5, 1:7, or 1:9 to prepare a suspension, and using a stone mortar mill (Masuko Sangyo Co., Ltd., Super Mass Colloid MKCA6-3INV), it was processed under the conditions of a clearance of 0.1 mm and a rotation speed of 1500 rpm (provisional test conditions), and the passed suspension was further processed under the conditions of a clearance <0.001 mm, a rotation speed of 1500 to 2000 rpm, and a current value of 4.5 A (this test condition), and the passed pulverized product suspension was recovered.

[0072] To the obtained pulverized product suspension, 5% by weight of Acremon cellulase KM (Kyowa Chemical Industry Co., Ltd.) was added, and saccharification treatment was carried out by incubating at 50 °C for 24 hours with stirring. Then, 2% by weight of dry yeast (Oriental Yeast) was added, and incubation was carried out at 40 °C for 3 days to perform parallel fermentation.

[0073] The viscosities of the suspension before surface treatment, after surface treatment (this test), after saccharification treatment, and after fermentation were measured using a laboratory vibrating viscometer VM10A-MH (Seko Nic). As shown in Table 8, it was confirmed that surface treatment reduces the viscosity of the suspension. [Table 8]

[0074] [Test Example 2] The logs of shirakamba were pulverized into fine powder in the same manner as in (1) of Example 1. The pulverized product and water were mixed at a weight ratio of 1:5, 1:7, or 1:9 to prepare a suspension, and using a mortar mill (Masuko Sangyo Co., Ltd., Super Mass Colloid Mill MKCA6-3INV), it was processed under the conditions of a clearance of 0.1 mm and a rotation speed of 1500 rpm (provisional test conditions), and the passed suspension was further processed under the conditions of a clearance <0.001 mm, a rotation speed of 1500 - 2000 rpm, and a current value of 4.5 A (this test condition), and the passed pulverized product suspension was recovered.

[0075] To the obtained pulverized product suspension, 5% by weight of acremolase KM (Kyowa Chemical Industry Co., Ltd.) was added, and saccharification treatment was carried out by incubating at 50 °C for 48 hours with stirring. The measurement results of the sugar content of each sample after the saccharification treatment are shown in Table 9. The sugar content is approximately proportional to the solid content concentration, and it was confirmed that sufficient saccharification had proceeded for the suspensions of all concentrations. [Table 9]

[0076] [Test Example 3] The logs of shirakamba were pulverized into fine powder in the same manner as in (1) of Example 1. The pulverized product and water were mixed at a weight ratio of 1:5 or 1:9 to prepare a suspension, and using a mortar mill (Masuko Sangyo Co., Ltd., Super Mass Colloid Mill MKCA6-3INV), it was processed under the conditions of a clearance of 0.1 mm and a rotation speed of 1500 rpm (provisional test conditions), and the passed suspension was further processed under the conditions of a clearance <0.001 mm, a rotation speed of 1500 - 2000 rpm, and a current value of 4.5 A (this test condition), and the passed pulverized product suspension was recovered.

[0077] To the obtained pulverized product suspension, 5% by weight of acremolase KM (Kyowa Chemical Industry Co., Ltd.) was added, and saccharification treatment was carried out by incubating at 50 °C for 24 hours with stirring. For this saccharified product, the sugar composition was analyzed using high performance liquid chromatography under the following conditions. Machine used: High Performance Liquid Chromatograph LC-20AD (Shimadzu Corporation) Detector RID-10A (Shimadzu Corporation) Column Asahipak NH2P-50 4E 4.6ID*250 (Shodex) Analysis conditions: Mobile phase CH3CN:H2O:phosphoric acid = 70:30:0.2, column temperature 50°C, flow rate 1 mL / min

[0078] In the suspension after saccharification treatment, xylose (Xyl), glucose (Glu), and sucrose (Suc) were detected (mass ratio Xyl:Glu:Suc = 1:3:0.2 in the 1:9 suspension, mass ratio Xyl:Glu:Suc = 2:9:0.1 in the 1:5 suspension). On the other hand, no sugars were detected from the suspension before saccharification treatment. It was confirmed that both cellulose and hemicellulose were decomposed by the saccharification treatment.

[0079] From the above examples and test examples, it was shown that efficient enzymatic saccharification and ethanol fermentation are possible by partially defibrating only the particle surface by surface treatment without performing fine pulverization up to single micron or submicron as in the prior art, and without completely defibrating the lignocellulose. It was also shown that the produced distillate is an ethanol composition rich in favorable components.

Claims

1. A step of dry-crushing a lignocellulosic biomass raw material to prepare a finely crushed product, A step of surface-treating the finely crushed product using a mortar mill, A step of saccharifying the surface-treated finely crushed product, and A step of ethanol-fermenting the saccharified product A method for producing an ethanol composition from a lignocellulosic biomass, comprising: wherein the finely crushed product after the surface treatment has d(10) of 4 to 15 μm, d(50) of 15 to 50 μm, and d(90) of 60 to 200 μm in the volume-based cumulative particle size distribution measured by the laser diffraction method.

2. The method according to claim 1, wherein the dry crushing is performed using a pneumatic impact mill.

3. The method according to claim 1, wherein the surface treatment is performed using an aqueous suspension of the finely crushed product.

4. The method according to claim 1, wherein the saccharification treatment and the ethanol fermentation are performed in parallel.

5. The method according to claim 1, further comprising a step of distilling the fermented product or its supernatant after the ethanol fermentation to recover a distillate.

6. A finely crushed product of a lignocellulosic biomass for use in saccharification treatment, wherein the particle surface is defibrated, and d(10) is 4 to 15 μm, d(50) is 15 to 50 μm, and d(90) is 60 to 200 μm in the volume-based cumulative particle size distribution measured by the laser diffraction method.

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