JP2008278825A - Method for producing bioethanol - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for producing bioethanol in high productivity even by using a carbohydrate raw material (mainly starchy raw material) having high lipid content. <P>SOLUTION: The method for producing bioethanol from a carbohydrate raw material containing lipids in addition to non-cellulosic carbohydrate (sugars) such as waste cake contains a step to properly crush the raw material, a step to remove the lipids, a hydrolyzing (liquefying and saccharifying) step, an ethanol fermentation step and a concentrating step for the fermented ethanol. The lipid removing step is carried out by an extraction method to use ethanol as an extractant (solvent). The defatted starch obtained as an extraction residue by the extraction step is used as a raw material for the ethanol fermentation. The ethanol fermentation is preferably carried out by using an acid-tolerant/salt-tolerant yeast represented by MF-121 strain. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a method for producing bioethanol (bioenergy: bioenergy) by ethanol fermentation from a carbohydrate-based raw material (biomass: bioresource) containing lipid together with non-cellulosic carbohydrate (sugar). In particular, the present invention is an invention suitable for use as a carbohydrate-based raw waste confectionery such as balm kuchen, short cake, and hot cake as a carbohydrate-based raw material, and further to a small plant that can operate even at a small production scale. It is a suitable invention.

  Here, waste pastry is mainly described as an example.

  Conventionally, waste confectionery is currently burned as it is or treated as garbage as industrial waste.

  However, waste confectionery has a high sugar content such as sugar and starch (carbohydrate), and also contains salt (containing salt as a hidden taste), so it generates pollutants such as dioxins. In addition, waste Western confectionery tends to rot, and unless it is processed quickly, it may rot and produce a foul odor. In order to store it, refrigeration is required, and excess fossil fuel (fossil energy) is consumed indirectly.

  On the other hand, global warming and the frequent occurrence of abnormal weather have come to be recognized as a major cause of life dependent on fossil fuels too much. At the same time, mass production, mass consumption and mass disposal in the second half of the 20th century have also been found to be activities that exceed the earth's capacity. The first half of the 21st century is thought to be a time to shift to a “sustainable development” society that uses all resources carefully and appropriately, and uses and uses materials and energy necessary for daily life without damaging the environment as much as possible. .

“Sustainable development” is a concept that focuses on the core concept of the report “Our Common Future” published in 1987 by the “World Committee on Environment and Development”, while satisfying the needs of future generations. Development that satisfies the needs of the current generation. (Glossary “Sustainable Development” [online], Ministry of Foreign Affairs [searched April 26, 2007], Internet <URL: htpp: //www.mofa.go.jp/mofaj/gaiko/kankyo/wssd/ (quoted from yogo.html>)
From the viewpoint of “sustainable development” above, it is urgent to produce bioethanol from carbon neutral (CO ₂ neutral) biomass. Carbon neutral means that even if carbon in plants emits CO ₂ into the atmosphere by oxidation reaction (combustion reaction), the CO ₂ is taken up from the atmosphere by carbon assimilation during the growth process. It means becoming plus or minus zero (neutral).

  When bioethanol is produced from corn, sugar, potatoes, and high-yielding rice, it will temporarily surpass, but will eventually run into food problems.

  In addition, since cellulosic biomass such as straws that are agricultural wastes and forest land residues produced by thinning, etc. are too hard, there are still many problems that must be solved in the saccharification process. In addition, the production design of bioethanol and the scale of commercialization differ depending on the type of biomass resource used. At present, most facilities cannot be operated unless a large scale of production is guaranteed and a constant supply of biomass is guaranteed.

  There is an urgent need for companies to reduce fuel costs and industrial waste expenses as much as possible, and to improve the system so that products can be developed and industrial activities can be carried out by incorporating environmental conservation mechanisms.

  From this point of view, if bioethanol can be produced at the place where waste confectionery is generated, the amount of industrial waste can be reduced, and at the same time, it becomes possible to use energy by mixing ethanol and fossil fuel produced in-house, and Life Cycle Assessment (LCA) : Lifecycle assesment) is improved.

  Incorporating this system makes it possible to create an image of corporate activities and product sales with the Lohas (Lifestyles of Health and Sustainability) thinking. For this reason, it is demanded by a group of food companies to put the system into practical use.

  Although it does not affect the patentability of the present invention, one of the applicants of the present application has previously proposed a “method for producing fuel from waste pastry” having the following configuration (Patent Document 1).

“It is characterized in that waste Western confectionery containing 45% by mass or more of saccharides based on solid content is subjected to alcohol fermentation with yeast to produce ethyl alcohol for fuel.”
Furthermore, one of the inventors of the present application has proposed a method for producing an alcohol having the following constitution using the acid / salt-resistant alcoholic fermentation yeast used in the present invention (Patent Document 2).

“A method for producing ethanol comprising adding an organic substrate containing a monosaccharide to a culture solution containing an alcohol-fermenting yeast strain MF-121 (Accession No. FERM P-19368) of the Issatchenkia orientalis species.”
JP 2004-242532 A JP 2004-344084 A

  However, the present inventors are not well aware of a method for producing bioethanol capable of meeting the above-mentioned demand and capable of small-scale operation.

  In addition, in the case of a carbohydrate-based raw material (biomass) such as the above-mentioned waste confectionery, it contains a lipid as a fermentation inhibitor and further contains various additives such as preservatives, emulsifiers, thickeners and the like. For this reason, although there was an idea like patent document 1, it is the present condition that it is not put into practical use from the viewpoint of fermentation efficiency.

  In view of the above, an object of the present invention is to provide a method capable of producing ethanol with good productivity even if it is a carbohydrate-based raw material (mainly starchy raw material) containing a high amount of lipid.

  In order to solve the above-mentioned problems, the present inventors are able to prepare a practical yeast medium by extracting the ground raw material in high-concentration ethanol in the process of diligent development. Furthermore, it has been found that alcoholic fermentation is also possible.

  That is, the present inventors selected rice (low lipid), bread (medium lipid), and baumkuchen (high lipid) in the starch-based food composition table of Table 1, and ethanol fermentation of sulfuric acid hydrolyzate was performed in Patent Literature. The salt-resistant and acid-resistant alcohol-fermenting yeast described in 2 was used for the test. In addition, before the test, all were pretreated with activated carbon. As a result, the cooked rice and bread were fermented, but in the case of Baumkuchen, even if pretreated with activated carbon, the yeast did not grow even. It was also found that cooked rice with less lipid content is faster in fermentation than bread, and that Baumkuchen can be ethanol fermented by degreasing with ethanol.

  Based on the above findings, the inventors have come up with a method for producing bioethanol having the following constitution.

Carbide-based raw materials containing lipids together with non-cellulosic carbohydrates (sugars) are subjected to an appropriate grinding process, followed by a lipid removal process, hydrolysis (liquefaction / saccharification) process, ethanol fermentation process, and fermentation ethanol concentration process. In the manufacturing method,
The lipid removal step is performed by an extraction method using ethanol as an extractant (solvent), and the defatted starch as the extract residue is used as a raw material for ethanol fermentation.

  In addition, although ethanol fermentation can use general-purpose ethanol-fermenting yeast (for example, Saccharomyces cerevisiae), it is performed using acid-tolerant / salt-tolerant yeast. Furthermore, alcohol-fermenting yeast MF-121 (accession number FERM) P-19368) is desirable.

  In the following description, the meaning of each value indicating the concentration is the following converted value in SI units.

%: Mass% (The number of g of the specific component with respect to 100 g of the total mass expressed in%)
w / v%: The number of grams of solute added expressed as a percentage of 100 cm ^{3 of} solvent g / L: Number of grams of solute added to 1 L of solvent (SI unit: kg / m ³ )
Hereinafter, a desirable mode for carrying out the present invention will be described. In addition, the conceptual diagram of this invention in the case of manufacturing bioethanol from waste confectionery in FIG. 1 is shown.

  The present invention basically includes a carbohydrate-based raw material containing a lipid together with a non-cellulosic carbohydrate, after appropriately undergoing a pulverization step, and then (1) a lipid removal step, (2) a liquefaction / saccharification step, and (3) an ethanol fermentation step. And (4) a method for producing bioethanol through the fermentation ethanol concentration step in this order.

  As a carbohydrate-based raw material, among the starch-based foods as shown in Table 1, wastes with medium to high lipids can be suitably used. That is, it is desirable to apply to the case where the lipid content is 4% or more, further 10% or more with a 0% moisture conversion value (total amount of components excluding moisture). When the lipid content is high, yeast growth (cell proliferation) is inhibited and ethanol fermentation is not performed, or even if yeast is grown, the efficiency of ethanol fermentation is extremely low (it takes time).

表１に示す以外に、澱粉系食品としては、カステラ、ドーナツ、スナック菓子、プディング（高脂質）等を挙げることができる。なお、これらの菓子類には、添加剤として、甘味料、食塩、増粘多糖類、防腐剤等が含有されている。

In addition to those shown in Table 1, examples of starch-based foods include castella, donuts, snacks, and puddings (high lipid). These confectionery products contain sweeteners, salt, thickening polysaccharides, preservatives and the like as additives.

  Sweeteners include sugar (sucrose), honey (mainly composed of glucose and fructose), trehalose, starch syrup, fructose (fructose), and other oligosaccharides. In the case of monosaccharides, these can be used as they are for alcohol fermentation, and in the case of disaccharides, they can be easily saccharified and contribute to shortening the hydrolysis process (liquefaction / saccharification) in total.

  Examples of thickening polysaccharides include carrageenan, agar, alginic acid, xanthan gum, gellan gum, pectin, guar gum, tara gum, locust bean gum and the like. These can be used as raw materials for ethanol fermentation if an appropriate enzyme is selected and mono-saccharified by enzymatic hydrolysis and / or acid hydrolysis. That is, the ethanol conversion raw material ratio by fermentation of the whole raw material increases.

  Examples of the preservative include benzoic acids, sorbic acids, and dehydroacetic acids. In many cases, these components have been feared to be inhibitors of ethanol fermentation. However, the present inventors have found that the preservative can be excluded from the ethanol fermentation system at the same time by the lipid removal step by ethanol extraction.

  Moreover, as other than the starch type, solids, semi-fluids and fluids such as various dessert jelly, fruit juice drinks, various dairy products (milk drinks, yogurt, cheese) can be exemplified. Many of these contain a large amount of carbohydrate-based components (carbohydrates) as described above, and therefore can be mixed with the above-mentioned starch-based carbohydrates or used alone as biomass.

  Hereinafter, each step will be described in detail (see FIGS. 2 and 3). In the examples, “A” indicates a stirrer, and “J” indicates a temperature control jacket.

  Here, the case where the waste confectionery mixture of Baumkuchen, donuts, and potato chips is used as the carbohydrate-based material (2.5 kg) is taken as an example.

  The component composition of the carbohydrate-based raw material is lipid: about 24%, carbohydrate: about 52%, protein: about 6%, and moisture: about 18%.

(1) Pulverization step When the hydrocarbon-based raw material is solid or semi-fluid, a general-purpose fine pulverizer can be used. As the fine pulverizer, a mixer (pulverizer) 12, a kneader or the like can be used.

(2) Lipid removal step This is performed by extraction using ethanol as an extractant (solvent). The extraction conditions (raw material concentration, ethanol concentration, temperature, time) at this time vary depending on the composition (particularly lipid content) and form (solid, fluid) of the carbohydrate-based raw material.

Raw material concentration (in the case of solid raw materials): 10-60 w / v%, more usually 20-40 w / v%
Ethanol concentration: 15-90 w / v%, more usually 45-80 w / v%, more usually 55-65 w / v%.

Temperature: normal temperature to 80 ° C, more usually 55 to 65 ° C
Time: 10 ~ 120min, more usually 30 ~ 60min
If the ethanol concentration or temperature is too low, it takes time for lipid extraction, which is not practical. Further, when the ethanol concentration is high, the lipid extraction efficiency tends to increase, but the increasing tendency gradually decreases as the concentration increases. Therefore, the ethanol concentration should not be too high considering the cost. If the temperature is too high, the amount of ethanol evaporated increases. Incidentally, the boiling point of ethanol is 78.3 ° C.

  What passed through the said lipid removal process performs solid-liquid separation. Here, when the starch-based raw material contains unnecessary or hardly soluble carbohydrates (starch and polysaccharides) in the main ethanol, the centrifugation is performed. In the case of an ethanol-soluble solution (when a beverage is used as a raw material), a solid content (including high water content) is taken out through a concentration step such as evaporation separation. Depending on the raw material, filter separation is also possible.

  Although the taken-out solid content is not inevitable, it is usually desirable to remove moisture by freeze drying, vacuum drying, or the like. This is to prevent the generation of bad odor due to decay or deterioration.

  In the above, when the carbohydrate-based raw material contains a large amount of water-soluble carbohydrates such as sugar, honey, and fructose, the water-soluble carbohydrate removal step is previously performed with water or low-concentration alcohol prior to the lipid removal step. It is desirable to do. At the same time, part of the salt and preservatives contained in the confectionery is also removed, reducing the load in the lipid removal step and the ethanol fermentation step, which are subsequent steps, contributing to productivity improvement.

  The water-soluble carbohydrate separated and recovered in this manner can be returned to the hydrolysis step.

(3) Hydrolysis process (liquefaction / saccharification process)
Usually, the hydrolysis step is made up of two stages of enzymatic hydrolysis and acid hydrolysis from the viewpoint of facilitating liquefaction.

  When the carbohydrate is starch, amylase (eg, α-amylase) is usually used as the enzyme. However, since confectionery also contains protein, it is pretreated using protease (protein degrading enzyme). It is desirable to do. Depending on the carbohydrate raw material, it is desirable to use a plurality of amylases in combination.

  The conditions for enzyme hydrolysis by starch-based carbonization vary depending on the type of enzyme. For example, in the case of α-amylase, the following conditions are used.

Starch milk concentration: 30-100 w / v%,
pH ... 6.5-7.0,
Liquefaction temperature / time ... 80 ~ 90 ℃ × 40 ~ 80min,
Enzyme use amount: Appropriate amount according to the enzyme type As the acid for acid hydrolysis, sulfuric acid, hydrochloric acid, oxalic acid, etc. can be used. The conditions at that time are as follows in the case of sulfuric acid.

Starch milk concentration ...
Acid normality ... 0.6-1.0N
Liquefaction temperature / time ... 100 ~ 110 ℃ × 90 ~ 150min,
The raw material (hydrolysis solution) that has undergone the hydrolysis step is subjected to solid-liquid separation. Prior to this solid-liquid separation, an adsorbent (activated carbon, alumina, synthetic zeolite, etc.) is added to prevent ethanol fermentation inhibiting components (contaminants) from entering the alcohol fermentation process as much as possible. It is desirable to keep it.

The solid-liquid separation is usually centrifugal separation from the viewpoint of productivity, but may be a filter, sedimentation separation, or the like. The saccharified solution thus obtained (a mixture of monosaccharides such as glucose and fructose) is usually 20 to 40 w / v% in terms of glucose.

(4) Ethanol fermentation process A pair of bioreactors 32 and 32 are prepared. The bioreactor 32 is usually provided with a circulation pipe having a culture solution circulation pump 36 and culture solution tanks (accumulation tanks) 38, 40 and the like for circulation operation (see FIG. 3).

  In the column of the bioreactor 32, a packed bed of the yeast-immobilized carrier of the alcohol-fermenting yeast strain MF-121 is formed. The immobilization carrier is not particularly limited, but for example, it is preferably formed of a plant fiber aggregate (cellulosic). The amount of fossil energy input can be reduced compared to synthetic resins made from petroleum. Specific examples of plant fiber aggregates include palm mats, hemp mats, loofah mats and the like. In addition, baffles are arranged at predetermined intervals so that the plant fiber aggregates are not unevenly distributed during the circulation operation. Alternatively, the MF121 strain of the present invention may be fixedly supported in advance on a plant fiber assembly and packaged to be replaceable.

  In addition, the present inventors have confirmed that palm mat has good air permeability and higher immobilization ability of MF121 strain than hemp mat and loofah (see FIGS. 4A and 4B). The culture solution used for immobilization was pH 2.5, glucose 3.0 w / v%, polypeptone 1.0 w / v%, yeast extract 0.5 w / v%, sodium sulfate 2.5 w / v%.

  Here, the alcohol-fermenting yeast MF-121 strain refers to “Issatchenkia orientalis alcohol-fermenting yeast MF-121 (accession number FERM P-19368)” described in Patent Document 2.

(4-0) Yeast culture and immobilization Immobilization (support) of the MF121 strain on a carrier can be performed, for example, by a conventional method. That is, a carrier such as coconut fiber may be immersed in a culture solution ingested with bacterial cells and immobilized by shaking culture, but the culture solution containing the bacterial cells is allowed to pass through a bioreactor described later for a predetermined time. Also good.

(4-1) Culture solution preparation step A nitrogen source and minerals are added to the saccharified solution (carbon source) obtained in the hydrolysis step (saccharification step), and the pH is adjusted.

  Here, the pH is generally adjusted to 3.0 or less, preferably pH 2.0 to 2.5, at which miscellaneous bacteria growth is suppressed. Thereby, even if the operation of ethanol fermentation is temporarily stopped, re-operation is possible without sterilization. That is, there is no necessity for continuous operation, and it may not be possible to temporarily secure the raw material.

  The composition of the culture solution is as follows. Furthermore, it is desirable to add a minute amount of mineral (Mg, Ca, Fe ion, etc.). For this reason, groundwater or seawater rich in minerals is used as the culture solution preparation water.

The alkaline water for adjusting the pH is not particularly limited as long as it does not react with the acid used in the acid hydrolysis to form a precipitate. For example, when the acid is sulfuric acid, NaOH _aq or KOH _aq is used, but ammonia water may be used. If ammonia water is used, ammonium sulfate, which is a reaction product of ammonia and sulfuric acid, can be used as a nitrogen auxiliary source for ethanol fermentation. For this reason, the usage-amount of polypeptone and yeast extract which are nitrogen sources can be reduced significantly.

Carbon source (glucose) ... 3-20w / v%, preferably 10-15w / v%
Nitrogen source (polypeptone, yeast extract, ammonia, etc.) ... Amount appropriate to the type of nitrogen source Mineral (Mg, Ca, Fe ion, etc.) ... 0-5w / v%, usually use industrial chemicals . In addition, as water, groundwater rich in minerals or deep sea water can be replenished using water added with ore powder.

(4-2) Ethanol fermentation process The culture solution prepared above is sent to the bioreactor, circulated, and subjected to alcohol fermentation for a predetermined time. Is pumped to the concentrating tower. This is because yeast activity is relatively decreased when the ethanol concentration is increased.

  Usually, the set concentration of ethanol is appropriately set in the range of 3 to 10 w / v% (preferably 4 to 8 w / v%). If the concentration is too low, the productivity of ethanol concentration decreases.

The reflux ratio when a part is taken out is 1/10 to 3/10 of the whole culture solution, preferably 1.5 / 10 to 2.5 / 10. If the reflux rate is too low or the reflux rate is too high, the productivity is lowered.
(5) Fermentation ethanol concentration process
(5-1) Primary concentration process It does not specifically limit, In this embodiment, it performs using the flash evaporator 44 (refer FIG. 3). The flash evaporator 44 includes a vacuum evaporation tank 44a having a heating jacket J and a stirrer A, and a condenser (heat exchanger) 44b having a vacuum pump of ethanol obtained by flash evaporation in the vacuum evaporation tank 44a. Yes.

  The fermented ethanol injected and flowed into the vacuum evaporation tank 44a is heated and vaporized by the inner wall heated by the heating jacket J of the vacuum evaporation tank 44a (separated from water), and then sent to the condenser and liquefied for primary concentration. It is recovered in the bioethanol recovery tank 45 as ethanol (bioethanol). The primary concentrated ethanol at this time is usually set appropriately within a range of 6 to 20 w / v%, preferably 8 to 15 w / v%.

(5-2) Secondary concentration step The primary concentrated ethanol thus obtained is 90 w / v% or more, preferably 95 w / v% or more (concentration of ethanol) using a conventional evaporation device (distillation device) and / or dehydration device. The azeotropic concentration is 96% by volume) to produce bioethanol for industrial or fuel use. This concentrated bioethanol can be partly recycled as ethanol (extractant) in the aforementioned lipid removal step.
(6) Culture liquid residue circulation process The culture liquid residue produced | generated at the said primary concentration process is below pH3 which a general miscellaneous germ does not propagate. For this reason, it can be temporarily stored in the culture medium residue tanks 46 and 48, and then returned to the culture medium preparation tank 34 for circulation. For this reason, in the production of conventional bioethanol, it is possible to effectively use the discarded culture solution residue.

  Hereinafter, the present invention will be described in more detail based on examples (see the flow of FIGS. 2 to 3).

The bioreactor 32 used a coconut mat (bulk density: 0.3 to 0.4 g / cm ³ ) as the packed layer (carrier) having a capacity of about 20 L (20 cmφ × 70 cmH).

  As a carbohydrate-based raw material, waste Western confectionery (a mixture of Baumkuchen, donut, potato chips: carbohydrate content 52%) is prepared.

  As the MF121 medium, 0.078 g / L of the MF121 strain was inoculated into the following mold synthetic medium “modified Czapeec” and allowed to grow for 72 hours.

Glucose 30g / L
Polypeptone 10g / L
Yeast extract 5g / L
The thus grown MF121 strain was transferred to a culture solution (12 L) for ethanol fermentation having the following composition.

NaNO ₃ 3g / L
K ₂ HPO ₃ 1g / L
MgSO ₄ · 7H ₂ O 0.5g / L
FeSO ₄ · 7H ₂ O 10mg / L
Glucose 100g / L
pH 2.5
This culture solution is circulated in each bioreactor 32 for a predetermined time (flow rate 0.2 L / min × 96 h) to carry the MF121 strain.

  (1) Crushing step: A mixture of waste pastry confectionery is put into a mixer 12 and pulverized to prepare a raw material.

  (2) Lipid removal step: Transfer 2.5 kg of the above pulverized product to a degreasing container 14 having an internal volume of about 20 L, add 12.5 L of 70 w / v% ethanol, and degrease under conditions of 60 ° C. × 1 h with stirring. I do.

(3) Solid-liquid separation step: Separation of solid and liquid into defatted starch (extracted residue) and lipid-dissolved ethanol (extract) under the condition of 3000 to 6000 min ⁻¹ × 10 min using the centrifugal separator 16. Do.

(4) Hydrolysis step (4-1) Enzyme hydrolysis step (enzyme saccharification step): 2.0 kg of defatted starch obtained by solid-liquid separation is transferred to the enzyme hydrolysis tank 18. Then, 2.5 L of water is added, and protease hydrolysis and α-amylase are sequentially added while stirring to perform enzyme hydrolysis. That is, after adding the appropriate amount of protease and hydrolyzing the protein at the optimum temperature of 50 ° C x 0.5h, add the appropriate amount of α-amylase to hydrolyze the starch (carbohydrate) at the optimum temperature of 85 to 90 ° C x 1h. Do.

(4-2) The enzyme saccharified solution obtained above is transferred to the autoclave 20 with the temperature control jacket J. Then, 12N H ₂ SO ₄ is added in an amount such that the H ₂ SO ₄ concentration becomes 0.8 N, and acid hydrolysis is performed under the condition of 105 ° C. × 2 h while stirring.

  (4-3) The saccharified solution obtained above is transferred to the contaminant removal tank 22, and 50 g of activated carbon added and stirred under conditions of 60 ° C. × 1 h is transferred to the centrifugal separator 24.

  Solid-liquid separation is performed by the centrifugal separator, and a saccharified solution as a raw material for ethanol fermentation is recovered. The saccharified solution obtained at this time is about 4.0 L, and the glucose concentration is about 30 w / v%.

(5) Ethanol fermentation step While adding the culture solution residue to the saccharified solution prepared in the above (4) to the culture solution preparation tank 34, 5N NaOH, 5N NH ₄ OH, and 10w of 10w / v% polypeptone Add / v% yeast extract (for nutritional supplementation) to prepare a culture solution (12 L) having the following composition.

Sodium sulfate / ammonium sulfate 2.5w / v%
Glucose 10w / v%
Polypeptone 0.1w / v%
Yeast extract 0.1w / v%
Then, the culture solution is supplied to the first culture solution tank 38 prepared in the culture solution preparation tank 34, and flows from the first culture solution tank 38 to the bottom of the reactor 32 through the circulation pump 36. It returns to the culture medium first tank 38 via the tank 40.

  In this way, the circulation operation is performed through the reactor 32 until the ethanol concentration reaches 4.5 w / v%. When the ethanol concentration reaches 4.5 w / v%, the valve is switched and 10 L is fed to the fermentation culture tank 42.

  At the same time, 10 L of the culture solution is transferred from the culture solution preparation tank 34 to the culture solution first tank 38.

  Further, to the culture solution preparation tank 34, a mixture solution consisting of 4L of saccharified solution, 4L of a culture solution residue generated from a flash evaporator 44, which will be described later, and 4L of inorganic salt-containing water (or groundwater) is added as described above. A culture medium having the above composition is prepared by adding a pH regulator and a yeast nutrition supplement.

(6) Ethanol concentration step The vapor evaporated under reduced pressure by the flash evaporator 44 is condensed and 8% ethanol is recovered in the bioethanol recovery tank 45. The amount of ethanol recovered at this time is about 5L.

  The culture medium residue generated by the ethanol separation in the flash evaporator 44 is temporarily stored in the culture medium residue first tank 46. The alcohol concentration of the culture solution residue at this time is about 1%. The culture solution residue in the culture solution residue first tank 46 can be sent to the culture solution adjustment tank 34 via the culture solution residue second tank 48. The culture residue second tank 48 has a buffering action for smoothly performing each process.

  In addition, the test result which performed fermentation comparison was used for FIG. 5 using shaking culture (batch type) and the bioreactor (continuous type) of this invention about MF121 stock | strain.

  The maximum ethanol concentration and ethanol conversion rate of the fermentation solution are slightly higher in the shaking culture. However, since the bioreactor has a faster ethanol production start time, it is estimated that ethanol productivity is nearly doubled.

  In addition, since the bioreactor has a strong image of aerobic fermentation and planned large-scale production, it has hardly been used for ethanol fermentation. However, the bioreactor used in the present invention feeds the culture solution with a pump, but does not allow substantial ventilation. For this reason, it is thought that it is semi-anaerobic fermentation, and liquid feeding is considered to correspond to stirring in shake culture.

It is a conceptual diagram of this invention in the case of obtaining bioethanol from waste confectionery. In the Example which manufactures bioethanol from the carbohydrate type raw material of this invention, it is a flowchart which shows to a hydrolysis process. It is a flowchart which shows the ethanol fermentation process after the same. It is a histogram which shows the amount of microbial cells per weight (A) and volume (B) which fixed the culture medium of MF-121 strain in the various support | carriers in a bioreactor by making it pass on the same conditions. It is a graph which shows the test result which performed fermentation comparison about MF121 stock | strain using the shaking culture (batch type) and the bioreactor (continuous type) of this invention.

Explanation of symbols

14 ... Degreasing container 32 ... Bioreactor 34 ... Culture solution preparation tank 42 ... Fermentation culture solution tank 44 ... Flash evaporator 46 ... Culture solution residue first tank

Claims (10)

Carbohydrate-based raw materials containing lipids together with non-cellulosic carbohydrates (saccharides) are appropriately crushed, then water-soluble carbohydrate removal step, lipid removal step, hydrolysis (liquefaction / saccharification) step, ethanol fermentation step and fermented ethanol In a method for producing ethanol including a concentration step,
A method for producing bioethanol, characterized in that the lipid removal step is carried out by an extraction method using ethanol as an extractant (solvent), and the defatted starch as the extract residue is used as a raw material for ethanol fermentation.   The method for producing bioethanol according to claim 1, wherein the ethanol fermentation is performed using acid-resistant / salt-resistant yeast.   The method for producing bioethanol according to claim 1 or 2, wherein the carbohydrate-based raw material has a lipid content of 4% or more (0% water equivalent value).   The method for producing bioethanol according to claim 1, 2 or 3, wherein in the lipid removal step, ethanol having a concentration of 15 to 90 w / v% is used and the temperature is set to room temperature to 80 ° C.   The method for producing bioethanol according to any one of claims 1 to 4, wherein the hydrolysis step is performed in two stages of enzyme hydrolysis and acid hydrolysis.   The method for producing bioethanol according to any one of claims 2 to 5, wherein an alcohol-fermenting yeast strain MF-121 (Accession No. FERM P-19368) of Issatchenkia orientalis species is used as the acid / salt-resistant yeast. .   The method for producing bioethanol according to any one of claims 1 to 6, wherein a part or all of the ethanol used in the lipid removal step is ethanol generated in the fermentation ethanol concentration step.   The method for producing bioethanol according to any one of claims 1 to 7, wherein the yeast medium residual liquid (culture liquid residue) generated in the fermentation ethanol concentration step is returned to the yeast medium preparation tank for circulation.   The bioethanol according to any one of claims 1 to 8, wherein the ethanol fermentation step is continuously carried out in a bioreactor that is a filling tank of a yeast-immobilized carrier of the alcohol-fermentable yeast MF-121 strain. Manufacturing method. The method for producing bioethanol according to claim 9, wherein the yeast immobilization carrier is formed of a plant fiber aggregate.

Images