WO2008123637A1

WO2008123637A1 - Production method of bio-ethanol from by-product of beer fermentation

Info

Publication number: WO2008123637A1
Application number: PCT/KR2007/002204
Authority: WO
Inventors: Jun Won Park; Seung Yong Lee
Original assignee: Bipl Co., Ltd.
Priority date: 2007-04-09
Filing date: 2007-05-04
Publication date: 2008-10-16
Also published as: JP2010523142A; KR20070077476A; KR100866032B1; EP2148914A1; CN101410498A

Abstract

Disclosed herein is a method of producing ethanol from a beer-fermenting yeast waste solution. Ethanol is extracted by fractional distillation from a beer- fermenting yeast waste solution containing about 5-12% ethanol. Desirably, the beer- fermenting yeast waste solution, where ethanol has been extracted, is used as a culture solution in culturing and fermentation to produce cellulose. Then, the product is hydrolyzed and fermented into ethanol. Further, a method of producing ethanol by injecting biomass into a beer-fermenting yeast waste solution is disclosed.

Description

PRODUCTION METHOD OF BIO-ETHANOL FROM BYPRODUCT OF BEER FERMENTATION

Technical Field

[1] The present invention relates to a method of producing bioethanol from beer fermentation by-products, such as a waste yeast solution, malt husks, etc. More particularly, the present invention relates to a method of extracting ethanol from a beer- fermenting yeast waste solution containing 5-12% ethanol by fractional distillation. Desirably, in the method of the present invention, after extracting ethanol from the beer-fermenting yeast waste solution, the remaining beer-fermenting yeast waste solution is used as a culture fluid in fermentation to generate cellulose, which is then converted to ethanol via hydrolysis and fermentation. Background Art

[2] Amidst the worldwide controversy over developing alternative energy sources to overcome high petrol prices, energy security, and the reinforcement of regulations on green house gases, bioethanol supplies have been produced worldwide as a fuel for the future. The Bush administration declared that by the year 2017, gasoline use will be decreased by 20% and the reduction will be compensated for by the usage of alternative energy sources such as bioethanol. Also, Japan, China, and ASEAN nations are planning to increase production of bioethanol.

[3] Bioethanol extracted from sugar cane, corn or other plants can be used as a fuel for vehicles alone or in combination with gasoline and is receiving a great deal of attention along with biodiesel as a representative renewable energy source. Not only does bioethanol reduce reliance on imported fuel, but also decreases generation of greenhouse gases as CO emitted from ethanol combustion is absent from the greenhouse gases list of the Kyoto Protocol. Also, bioethanol can be supplied at existing facilities (gas stations) and thus is easily employed commercially unlike other clean fuels that require installation of extra facilities (recharging centers, etc.) for supply thereof. As such, the increase in demand and interest in bioethanol has resulted in increasing production thereof.

[4] However, increasing attention upon bioethanol as an alternative energy source has caused a rapid increase in demand for corn, sugar cane, meal, etc., thus being the primary cause of increasing grain prices. According to a Bloomberg investigation of ethanol manufacturing businesses in Brazil, the US, and Canada, the total number of operating ethanol producing facilities in these three countries was 448 with a total production of 10,034,500,000 gallons in November, 2006. Brazilian facilities utilizing sugar cane as their raw material constituted 39.4% of total ethanol production. On the other hand, US facilities made up 58.8% of the total and 99.7% of these utilized corn as their raw material while Canada had a low market share of 1.7%, using only corn.

[5] According to the Renewable Fuels Association (RFA), a US ethanol industry group, there are currently 48 ethanol facilities under construction and 7 ethanol facilities under renovation for expansion in the US. Accordingly, the production of ethanol in the US is expected to increase to approximately 69,000,000,000 gallons by 2007, which will require approximately 24,080,000,000 bushels (1 bushel equals 25.4kg) of corn to produce, 23% of the US 2006/2007 estimated production. In the US, since ethanol manufacturing is expected to continue in the future, the use of and demand for the economically important agricultural product corn is expected to continue and increase along with the production of bioethanol. It is also expected that such an increase in corn demand will cause cost increases in the fields of livestock farming, poultry farming, and food businesses using grains as raw materials, leading to an increase in consumer prices for food, livestock, etc.

[6] Therefore, in order to produce bioethanol as an alternative energy source capable of replacing petroleum without a rapid increase in grain prices, it is necessary to find a diverse range of sources for bioethanol other than the originally used grain resources, such as corn, sugar cane, etc.

[7] On the other hand, a waste yeast solution formed after beer fermentation is generally categorized as waste to be disposed of. Thus, financial and environmental problems may arise with regard to disposal thereof. Disclosure of Invention

Technical Problem

[8] The present invention is conceived to solve the above problems, and an aspect of the present invention is to provide a method of easily producing ethanol without causing the problems as described above. Technical Solution

[9] In accordance with one aspect of the present invention, a method of producing bioethanol utilizes a waste yeast solution formed after producing beer in place of grain products such as corn or sugar canes. In this regard, during beer fermentation, a beer- fermenting yeast waste solution, malt husks, and other by-products are produced. Conventionally, such by-products are treated as wastes, causing additional costs and environmental problems.

[10] In one embodiment of the present invention, ethanol is extracted or distilled from the beer-fermenting yeast waste solution. Furthermore, even after ethanol is extracted, since the remaining beer-fermenting yeast waste solution still contains nutrition that microorganisms require, cellulose-producing bacteria is inoculated to produce cellulose, from which ethanol is produced by known methods.

[11] According to another embodiment of the present invention, the beer- fermenting yeast waste solution may be used as fermenting bacteria in a conventional process of extracting bioethanol from biomass, such as corn, sugar cane, etc. Conventionally, when ethanol is produced using yeast and monosaccharides formed via hydrolysis of biomass, yeast makes up approximately 20% of operating costs. According to the present invention, however, a beer- fermenting yeast waste solution is used as fermenting bacteria to reduce costs and to solve the problem of disposing of the beer- fermenting yeast waste solution.

[12] According to yet another embodiment of the present invention, in the process of producing ethanol from biomass, malt husks, one by-product of the beer-making process, can be used as biomass. Since a substantial amount of malt husks are produced in the process of producing beer, they can be advantageously used as an energy source rather than being disposed of as waste. Malt husks contain ingredients such as cellulose that can be decomposed for use as a raw material for ethanol production.

Advantageous Effects

[13] According to the present invention, bioethanol is produced with a beer-fermenting yeast waste solution or malt husks produced after beer production instead of grains such as corn or sugar canes. Thus, the method according to the present invention does not create problems such as increased costs associated with food resource, competition for arable land, and deforestation. Also, the method of the present invention can solve the problem of disposing of wastes generated in the process of producing beer. Best Mode for Carrying Out the Invention

[14] Exemplary embodiments of the present invention will hereinafter be described in detail, but it should be noted that the present invention is not limited to the embodiments.

[15] The present invention relates to a method of producing high concentrations of ethanol from a sterilized beer- fermenting yeast solution with gamma rays.

[16] Depending on the number of times beer- fermenting yeast is used, the yeast has different states and the fermented solution has different ingredients. Thus, the yeast is generally disposed of after being used four times in beer factories which produce beer on a large scale via a filtering process to remove the yeast and residue from raw materials. In microbreweries which produce beer with malt, hops, yeast, and other raw materials based on traditional production methods, yeast is replaced or added depending on the degree of fermentation. [17] First, in order to identify the composition of a beer- fermenting yeast waste solution, an elemental analyzer (EAl 108CHNS-O available from Fisons) was used to analyze C, H, N, S, and O constituents.

[18] As shown in Table 1, the beer-fermenting yeast waste solution comprised approximately 80% of C and O, and a very small amount of S. When the dry weight of a beer-fermenting yeast waste solution used four times is compared with a solution used seven times, a great difference in constituents is observed. As the number of times a beer- fermenting yeast waste solution is used increases, the constituent proportions and dry weight of the beer-fermenting yeast waste solution change. Also, in addition to C, H, N, S, and O, trace minerals such as Na, Fe, Ca, Mg, P, etc. are observed by an ICP- Atomic Emission Spectrometer (JY 38 Plus, available from Jobin-Yvon).

[19] Table 2 shows the concentrations of ethanol and acetic acid in beer- fermenting yeast waste solutions, which are important features of the present invention. [20] Table 2 shows the variation in concentrations of ethanol and acetic acid in different types of beer- fermenting yeast waste solutions used various numbers of times. The beer-fermenting yeast waste solution reused 4 times contains approximately 4.58% ethanol and no acetic acid, while the beer-fermenting yeast waste solution used 7 times contains approximately 12.42% ethanol and approximately 13.82% acetic acid, the highest values in table 2. A beer-fermenting yeast waste solution from a microbrewery contained approximately 5.42% ethanol and approximately 0.11% acetic acid.

[21] Table 1

[22] [23] Table 2

Concentration of ethanol anc acetic acid in beer-fermenting yeast waste solution by gas chromatographic analysi

[24] Hereinafter a method of producing bioethanol via production and fermentation of pure cellulose not containing lignin or hemicellulose from a beer- fermenting yeast waste solution from which bioethanol is extracted will be described.

[25] It is reported that microorganisms capable of producing pure cellulose from a beer- fermenting yeast waste solution include Acetobacter sp., Agrobacterium sp., Rhizobium sp., Pseudomonas sp., Sarcina sp., etc. Acetobacter sp. is not a cell wall polymer found in eukaryotes, but secretions of extracellular fibril that can generate large batches of cellulose, attracting intensive research.

[26] Also, for generation of microbial cellulose, stirred cultivation is more cost effective than fixed culturing. However, in the case where the microbial cellulose-producing bacteria are subjected to stirred or shock culturing, shear stress inside the culture medium causes creation of mutants which are unable to generate cellulose. Since the mutant proliferates faster than the microbial cellulose-producing bacteria, the producers are eliminated and are replaced by the non-producers in continuously ventilated stirred cultivation (Valla, S. and Kjosbakken, J., J. General Microb. 128: 1401-8, 1982). Thus, fixed culturing is traditionally used to generate the microbial cellulose even though fixed culturing is labor intensive, requires long culturing periods, and suffers from extremely low productivity.

[27] Therefore, there is an urgent need to develop culturing conditions that do not generate mutants or decrease the possibility of generation thereof even in stirred culturing and to find alternative culture mediums capable of reducing the cost of producing microbial cellulose.

[28] On the other hand, according to one known method, microbial cellulose are produced by stirred culturing of acetobacter xylinum in a culture medium containing peptone, yeast extracts, glucose, calcium citrate, ethanol, etc. However, this method is disadvantageous in that it is economically inefficient and uses costly peptone, yeast extracts, etc. for production of cellulose (Korean Patent Laid-open Publication No. 10-1998-067009).

[29] In this regard, the present inventors have already invented a method of producing a high yield of bioethanol from microbial cellulose by culturing microbial cellulose without generation of mutants incapable of degrading cellulose even in culturing conditions exhibiting significant shear stress (Korean Patent Laid-open Publication No. 10-2005-0022591).

[30] In Example 2, there is a description of one method wherein cellulose is produced from a beer-fermenting yeast waste solution according to one embodiment of the present invention using the foregoing method and hydrolyzed into a saccharide, which is then used to produce ethanol by fermentation.

[31] Hereinafter will be described a method of producing bioethanol using a beer- fermenting yeast waste solution as fermenting bacteria after processing biomass, such as corn and sugar cane, which are currently used as main raw materials in the production of bioethanol. Generally, the materials contain three main constituents: cellulose, hemicellulose, and lignin in a ratio of about 4:3:3. However, it should be noted that the ratio is only an approximation. For example, soft wood has an approximate ratio of 42:25:28 and corncobs have an approximate ratio of 40:36: 13. Additionally, a daily saccharide forms approximately 8%; whereas the city disuses contain approximately 75-90% of cellulose. Here, cellulose and hemicellulose can be converted into ethanol. First, these raw materials are subjected to delignification to separate lignin, cellulose, and hemicellulose.

[32] The separated cellulose is processed to produce ethanol in the same way as in the production of ethanol, where cellulose produced from the above-mentioned beer- fermenting yeast waste solution is hydrolyzed to produce ethanol.

[33] Hemicellulose is a polymer of D-glucose, D-mannose, D-galactose, D-xylose, L- arabinose and uronic acid, and is categorized into D-galactan, D-mannan, and D-xylan according to constituent composition. However, these components don't exist as homogeneous glycans but as heteroglycans containing various saccharides. Also, hemicellulose is mostly distributed in an intermediate lamella layer of a plant cell wall and is tightly bound to cellulose and lignin. Since hemicellulose has a variety of forms and is present in varying quantities depending on the kind of plant, tissue type, growing conditions and environments, physiological requirements, storage/extraction methods, etc., it is difficult to obtain an even sugar composition ratio. In general, hemicellulose is in the form of D-xylose with a side chain of L-arabinose. An annual plant or deciduous tree contains hemicellulose with xylan in the greatest quantity, but each plant has a different concentration of xylan. Typically, the content of xylan is higher in broadleaf trees (11-25%) than in needle-leaf trees (3-8%). A main hemicellulose carbohydrate in agricultural by-products is D-xylose, and corn by-products have a xylan content of 17-31%. (Fenel, D. and Wegner G., Wood chemistry, ultrastructure, and reactions, Berlin, Walter de Gruyter Co., Berlin, plO6, 1884).

[34] In Example 3, there is a description of a method of producing ethanol from hemicellulose separated from biomass. [35] Generally, fermentation of ethanol from cellulose is well known (CR. Wilke, and

H.W. Blach, Lawence Berkeley Lab., Univ. of California, Berkley, CA. LbL-9909, 1979). Mode for the Invention

[36] Example 1

[37] Example 1 illustrates extraction of bioethanol using a beer-fermenting yeast waste solution isolated after being used seven times, which contains the greatest amount of ethanol.

[38] As shown in Table 2, the beer-fermenting yeast waste solution, after being used seven times, contains 12.42% ethanol and 12.82% acetic acid.

[39] IL of the beer- fermenting yeast waste solution (Hite beer, Masan factory) isolated after being used seven times was extracted by atmospheric distillation.

[40] As a result, approximately 120ml of bioethanol and approximately 135ml of acetic acid were obtained.

[41]

[42] Example 2

[43] After centrifuging a beer-fermenting yeast waste solution at 4000rpm, 5OmL of a supernatant was placed in a 25OmL Erlenmeyer flask and sterilized at 121 ⁰C for 15 minutes. Microbial cellulose generating bacteria, Gluconacetobacter hansenii PJK bacteria, was inoculated thereto and spun in a shock culturing device at 30 ⁰C at a speed of 200 rpm for a day until it was completely cultured. Then, the supernatant of the completely cultured solution was inoculated with 5OmL of a 5%(v/v) culture medium solution containing l%(v/v) ethanol in a 25OmL Erlenmeyer flask and spun at 30 ⁰C at a speed of 200 rpm for five days in a shock culture. After cultivation, the cultured solution was centrifuged at 4000 rpm for 20 minutes. Then, the supernatant was removed, and the remaining product was washed with distilled water, centrifuged twice by the foregoing process, and frozen at minus 50 ⁰C, thereby obtaining a dry sample of the microbial cellulose including fungal bodies. The microbial cellulose containing the fungal bodies was mixed with 2OmL of a 0.3N sodium hydroxide solution and boiled for five minutes to completely dissolve the fungal bodies. The pure microbial cellulose from which the cells had been eliminated was thoroughly washed to neutrality and lyophilized, thereby allowing measurement of the dry weight of the microbial cellulose. The dry weight of the fungal bodies was estimated based on the di fference between the dry weight of the microbial cellulose having the fungal bodies and that of the pure microbial cellulose. Consequently, the fungal bodies in the culture medium and the microbial cellulose were found to have dry weights of 3.13g/L and 2.5g/L, respectively. [44] The obtained cellulose was converted into saccharides using 1% hydrochloric acid solution and 1% sodium hydroxide (for neutralization) by hydrolysis at 100 ⁰C for an hour after adding 15mL of extracting solvent to each Ig of sample powder.

[45] Subsequently, a beer-fermenting yeast waste solution (Hite beer, Masan factory) was added to the hydrolyzed saccharides and fermented in a sealed state at room temperature for ten days, producing approximately 2mL of ethanol.

[46]

[47] Example 3

[48] Im of corn, a representative raw material of ethanol, was pulverized and mixed with water to adjust the pH thereof, followed by heating and hydrolyzing at 100 ⁰C for one hour. Then, while decreasing the temperature to about 60 ⁰C, amylo-glucosidase as a saccharifying enzyme was added to the product for saccharification. The saccharified raw material was inoculated with a beer- fermenting yeast waste solution (Hite beer, Masan factory) and fermented at room temperature, thereby producing 350ml of ethanol.

[49]

[50] Example 4

[51] First, lkg of malt husks was ground through a 100 mesh sieve and hydrolyzed with

1% sulfuric acid at about 90 to 100 ⁰C for about 50 minutes. Then, the suspension was cooled and dried via filtering, washing, and pressing. The drying operation was required to prevent sulfuric acid from becoming thin. The remaining acidic solution was neutralized with lime. The neutralized solution was mixed with a beer-fermenting yeast waste solution and fermented in a sealed state at room temperature for 10 days, thereby producing 92ml of ethanol.

[52]

Industrial Applicability

[53] The present invention provides a method of producing bioethanol using a beer- fermenting yeast waste solution or malt husks created during production of beer without using grains such as corn or sugar cane used hitherto. Hence, the present invention helps reduce pressure on food prices, limits competition for arable land, and prevents deforestation. Also, the present invention can solve the problem of disposal of wastes generated during beer production processes.

Claims

[1] A method of producing bioethanol, wherein ethanol is produced from a byproduct generated during beer fermentation.

[2] The method according to claim 1, comprising: distilling the by-product to extract ethanol, wherein the by-product is a beer- fermenting yeast waste solution.

[3] The method according to claim 2, comprising: generating cellulose by inoculating a remaining beer-fermenting yeast waste solution with cellulose generating bacteria after extraction of ethanol; and producing ethanol from the cellulose.

[4] The method according to claim 1, wherein the by-product is a beer-fermenting yeast waste solution, the beer-fermenting yeast waste solution being used as fermenting bacteria in a process of producing ethanol from biomass.

[5] The method according to claim 4, wherein the biomass is selected from the group consisting of corn and sugar cane.

[6] The method according to claim 1, wherein the by-product is malt husks, the malt husks being used as biomass in a process of producing ethanol from the biomass.