Method for producing high-protein soybean meal

Abstract

The object of the present invention is to provide a method for producing high-protein soybean meal having excellent nutritional properties, and to provide a method for producing high-protein soybean meal that can also produce industrially valuable ethanol when producing the high-protein soybean meal. [Solution] A method for producing high-protein soybean meal, which comprises mixing soybean meal with water, subjecting the resulting mixture to saccharification and alcoholic fermentation, adding cellulase for the saccharification, and adding microorganisms for the alcoholic fermentation, and a method for producing high-protein soybean meal, which comprises carrying out the saccharification and alcoholic fermentation in the same process.

Description

[Technical Field]

[0001] The present invention relates to a method for producing high protein soybean meal. [Background technology]

[0002] Soybean meal has been widely used as a feed ingredient. For example, in order to provide poultry with the necessary nutritional amount and achieve a sufficient water absorption effect, a poultry feed has been developed in which 1 to 40 parts by mass of starch, 10 to 80 parts by mass of soybean meal, and 1 to 30 parts by mass of fat or oil are molded, and the feed is fed while maintaining the particle shape by absorbing water before use (Patent Document 1). In particular, soybean meal has a high crude protein content and has often been incorporated into feed to create a nutritious feed. For example, it has been discovered that by using soybean meal instead of a binder in solid fish feed, not only is it possible to produce solid feed with a moderate hardness that is easy for fish to ingest, but the solid feed also has a uniform particle size, a relatively high crude protein content, and is rich in nutritional value (Patent Document 2). It has also been reported that by using dehulled soybean meal, which has a crude protein content about 10% higher, as the soybean meal component mixed into livestock feed, the amount of soybean meal required to ensure the same crude protein content can be reduced by about 10% (Patent Document 3).

[0003] [Patent Document 1] Patent Publication No. 2005-295814 [Patent Document 2] Patent Publication No. 05-076291 [Patent Document 3] Patent Publication No. 2004-113106 DISCLOSURE OF THE INVENTION [Problem to be solved by the invention]

[0004] An object of the present invention is to provide a method for producing a high-protein soybean meal with excellent nutritional properties. Another object of the present invention is to provide a method for producing high-protein soybean meal that can also produce industrially valuable ethanol when producing high-protein soybean meal. [Means for solving the problem]

[0005] As a result of extensive research to solve the above problems, the present inventors have discovered that the crude protein content in soybean meal can be increased by performing saccharification and alcoholic fermentation in the same process, and that ethanol productivity can be increased by performing saccharification and alcoholic fermentation in the same process, leading to the completion of the present invention.

[0006] Specifically, the present invention includes the following aspects. [1] A method for producing high-protein soybean meal, comprising mixing soybean meal with water, subjecting the resulting mixture to saccharification and alcoholic fermentation, adding cellulase for the saccharification, and adding yeast for the alcoholic fermentation. However, the method is characterized in that the mixture of soybean meal and water is not sterilized before the saccharification treatment and / or alcoholic fermentation treatment, and the saccharification treatment and alcoholic fermentation treatment are carried out by solid fermentation. [2] The production method according to [1], wherein the saccharification treatment and the alcoholic fermentation treatment are carried out in the same process at a temperature of 25 to 45°C. [3] A method for producing high-protein soybean meal according to [1] or [2], characterized in that when the ratio of the crude protein content to the carbohydrate content (crude protein content / carbohydrate content) of the raw soybean meal is taken as 100, the ratio of the crude protein content to the carbohydrate content (crude protein content / carbohydrate content) of the obtained high-protein soybean meal is 130 to 160. [4] A method for producing high-protein soybean meal according to any one of [1] to [3], characterized in that the amount of ethanol produced per 100 g of dry weight of soybean meal in the alcohol fermentation treatment is 3.5 to 10 g. [5] The production method described in any one of [1] to [4], characterized in that the amount of water in the reaction system in which the saccharification treatment and the alcoholic fermentation treatment are performed is 40 to 60 mass%. [Effects of the Invention]

[0007] By carrying out the present invention, ethanol can also be obtained when producing high-protein soybean meal. The crude protein content of feed can be increased by using the resulting high-protein soybean meal as a feed ingredient. When the high-protein soybean meal of the present invention is used as a feed ingredient, feed with increased energy value can be fed to livestock and aquatic organisms such as fish and crustaceans. Furthermore, the ethanol obtained can be used as bioethanol for a variety of purposes. BEST MODE FOR CARRYING OUT THE INVENTION

[0008] (soybean meal) Soybean meal is soybean meal obtained by evaporating the organic solvent after an oil extraction process in which the oil in soybeans is extracted using an organic solvent such as n-hexane, or by extracting the oil from soybeans using a press. It contains 8 to 15% by mass of moisture. It is preferable to use soybean meal in an amount that accounts for preferably 40 to 60 mass%, more preferably 55 to 45 mass%, and even more preferably 52 to 48 mass%, on a dry weight basis, in the total reaction system in which saccharification treatment and alcohol fermentation treatment are carried out.

[0009] (Water and other additives) The water in the present invention is not particularly limited, and may be, for example, distilled water, pure water, tap water, sterilized water, or physiological saline. The amount of water used is preferably 40 to 60 mass %, more preferably 45 to 55 mass %, and even more preferably 48 to 52 mass % of the total reaction system in which saccharification treatment and alcoholic fermentation treatment are carried out. Such a water content is preferable because it allows for solid fermentation. Here, "solid state fermentation" refers to a fermentation method in which the moisture content is set lower than in liquid fermentation, and in which almost no waste liquid is discharged not only during the fermentation period but also after the fermentation is completed.

[0010] Additives such as minerals, sugars, amino acids, culture medium components, enzymes, and microorganisms may be added in an amount of 0 to 10 parts by mass per 100 parts by mass of a mixture of soybean meal and water before saccharification and alcoholic fermentation. Specific examples of minerals include phosphorus, magnesium, sodium, potassium, and iron. Specific examples of sugars include sucrose, glucose, maltose, and oligosaccharides. Specific examples of amino acids include glutamic acid and lysine, and may also be constituent amino acids of crude protein, non-constituent amino acids such as GABA, and hydrolysates of crude protein. Specific examples of culture medium components include yeast extract, malt extract, and peptone. Specific examples of enzymes for saccharification include cellulases, hemicellulases, glucosidases, and mixtures thereof. In the saccharification process of the present invention, the cellulases (fibrous decomposition enzymes) used include cellulases produced by microorganisms of the genus Acremonium, particularly cellulases produced by Acremonium cellulotycus (product name: Acremocellulase KM, manufactured by Kyowa Kasei Co., Ltd.), cellulases produced by microorganisms of the genus Aspergillus, particularly cellulases produced by Aspergillus niger (product name: Cellulase from Aspergillus niger, manufactured by MP Biomedicals, Inc.), and cellulases produced by Aspergillus niger (product name: Cellulase from Aspergillus niger, manufactured by Tokyo Chemical Industry Co., Ltd.). In the present invention, it is preferable to use cellulase produced by Acremonium cellulotycus. Specific examples of microorganisms for alcoholic fermentation treatment include filamentous fungi, yeasts such as Saccharomyces cerevisiae, Shizosaccharomyces pombe and Pichia stipitis, Zymomonas mobilis, etc. For the alcoholic fermentation treatment of the present invention, it is preferable to use yeasts such as Saccharomyces cerevisiae, and particularly yeasts that can be used in solid fermentation methods are preferred. Hereinafter, water or water and these additives will be collectively referred to as "water, etc." Among these additives, water-soluble ones may be solubilized in the water and added.

[0011] (mixture) In the present invention, "mixing soybean meal with water, etc." refers to mixing soybean meal with water, etc., manually or by device. The more uniform the water distribution in the solids after mixing, the more efficient the saccharification or alcoholic fermentation process, which is desirable; however, even if the water distribution in the solids is uneven, the purpose of saccharification or alcoholic fermentation can be achieved. Generally, it has been considered desirable to sterilize a mixture of soybean meal and water, etc., in an autoclave during saccharification or alcoholic fermentation to prevent the growth of microorganisms other than the desired microorganisms. However, it has been found that the present invention makes it possible to omit the sterilization process prior to saccharification or alcoholic fermentation.

[0012] (Saccharification treatment) The saccharification treatment in the present invention refers to the decomposition of fiber (such as cellulose) contained in soybean meal into glucose by adding a fibrous decomposing enzyme to a mixture of soybean meal, water, etc., at a concentration of 0.01 to 1.0% by weight. The fibrous decomposing enzyme used in the saccharification treatment can be cellulase alone or cellulase in combination with enzymes such as hemicellulase or glucosidase. The amount of cellulase added is preferably 0.01 to 6% by weight, more preferably 0.05 to 2% by weight, and even more preferably 0.05 to 1% by weight, based on the mixture of soybean meal and water. In addition, the enzyme used in the saccharification treatment may be any enzyme capable of decomposing fiber, and may be a commercially available product, a culture medium obtained by cultivating a filamentous fungus or a further purified version thereof, or the filamentous fungus itself.

[0013] (Alcoholic fermentation process) In the present invention, alcoholic fermentation refers to a process in which a microorganism is inoculated into a mixture of soybean meal and water, or a saccharified mixture of soybean meal and water, to produce ethanol using the microorganism. Regarding the microorganisms used, yeasts such as Saccharomyces cerevisiae, Shizosaccharomyces pombe, and Pichia stipitis can be used. Other than yeasts, any microorganism capable of alcoholic fermentation, including genetically modified ones, can be used, such as Zymomonas mobilis, a bacterium capable of alcoholic fermentation. Microorganisms preserved in a slant or frozen state can be used, but when using Saccharomyces cerevisiae, commercially available baker's yeast can also be used. When using microorganisms preserved in a slant or frozen state, it is preferable to pre-culture them in a liquid medium before use and use the pre-culture solution. The liquid medium used for pre-culture may be any suitable medium for culturing yeast or bacteria, such as 1% by mass yeast extract, 2% by mass peptone, and 3% by mass glucose. In the present invention, yeast such as Saccharomyces cerevisiae is preferably used as the microorganism for alcoholic fermentation, and yeast suitable for solid-state fermentation is particularly preferred. The amount of yeast used is preferably a yeast suspension prepared to have an optical density (OD) of 0.2 when measured at 660 nm, and added so that the amount of yeast present in the total reaction system (yeast (suspension) + meal + added water) is 0.05 to 0.15. It is more preferred to add the yeast so that the OD is 0.05 to 0.1.

[0014] (When saccharification and alcoholic fermentation are carried out in separate processes or in the same process) In the present invention, a mixture containing enzymes, microorganisms, soybean meal, water, etc. is subjected to saccharification and alcoholic fermentation. Although the saccharification and alcoholic fermentation may be carried out in separate steps (called "single-stage multiple fermentation"), it is preferable to carry out the saccharification and alcoholic fermentation in the same step (called "parallel multiple fermentation") because this results in a greater amount of alcohol being produced. Here, performing these steps separately means, for example, performing saccharification treatment and then alcoholic fermentation treatment. When saccharification and alcoholic fermentation are carried out in separate steps, the saccharification temperature is preferably 40 to 60°C, more preferably 42 to 58°C, and even more preferably 45 to 55°C. On the other hand, the fermentation temperature is preferably 20 to 40°C, more preferably 22 to 38°C, and even more preferably 25 to 35°C. Furthermore, when saccharification and alcohol fermentation are carried out in the same process, the treatment temperature is preferably 25 to 45°C, more preferably 27 to 43°C, and even more preferably 30 to 40°C. The saccharification treatment time and the alcoholic fermentation treatment time (the total treatment time when the saccharification treatment and the alcoholic fermentation treatment are carried out in separate steps) are preferably 4 to 180 hours, more preferably 72 to 180 hours, and even more preferably 24 to 180 hours.

[0015] (After solid-liquid separation, drying and distillation) Soybean meal is mixed with water and subjected to saccharification and alcoholic fermentation, followed by solid-liquid separation as needed and drying. The resulting product is called high-protein soybean meal. Drying can be performed by heat drying, vacuum drying, freeze drying, spray drying, or any other method that can evaporate the water and ethanol from the mixture that has been subjected to saccharification and / or alcoholic fermentation. If ethanol is recovered by steam distillation or other methods before drying, the recovered ethanol can be used for industrial purposes or as fuel. In the present invention, the amount of ethanol produced per 100 g of dry weight soybean meal is preferably 3.5 to 10 g, more preferably 3.8 to 9 g, and even more preferably 4 to 8 g. The saccharification treatment and alcoholic fermentation treatment are preferably carried out by solid fermentation, which is preferable because it does not require the above-mentioned solid-liquid separation and does not produce waste liquid.

[0016] (High protein soybean meal) The high-protein soybean meal of the present invention is a high-protein processed soybean meal that has a higher crude protein content than the raw material soybean meal due to saccharification and alcohol fermentation of soybean meal, and the crude protein content is 55 to 65% by mass, preferably 55 to 62% by mass, of the dry matter of the high-protein soybean meal. For example, if the production method of the present invention is carried out using soybean meal containing approximately 50% by mass of crude protein in the dry matter as a raw material, high-protein soybean meal with a crude protein content of approximately 58% by mass in the dry matter can be obtained. Furthermore, for example, if the production method of the present invention is carried out using high-protein soybean meal, which has a high crude protein content of approximately 54% by mass in the dry matter, as a raw material, high-protein soybean meal with a crude protein content of approximately 62% by mass in the dry matter can be obtained. Furthermore, when the ratio of crude protein content to carbohydrate content (crude protein content / carbohydrate content) of the raw soybean meal is 100, the ratio of crude protein content to carbohydrate content (crude protein content / carbohydrate content) of the resulting high-protein soybean meal is preferably 130 to 160, more preferably 135 to 155, and even more preferably 140 to 150. In the production method of the present invention, the more carbohydrates (crude fiber, soluble nitrogen-free substances (starch, sugars, etc.)) in the raw soybean meal are consumed through saccharification and alcohol fermentation, the more the amount of carbohydrates decreases and the crude protein / carbohydrate ratio increases, i.e., the proportion of crude protein in the high-protein soybean meal increases. The crude protein content here refers to the total nitrogen determined by the Kjeldahl method multiplied by 6.25. A compound feed containing the high-protein soybean meal produced by the production method of the present invention can be used as a feed without any problems.

[0017] (feed) The high-protein soybean meal obtained by the production method of the present invention can be mixed with feed ingredients or feed additives containing sugars, proteins, amino acids, fiber, minerals, oils, antibacterial components, etc. and used as feed. Specific examples of feed ingredients and feed additives include corn, sorghum, corn gluten field, corn starch, rice bran, regular soybean meal, hyper-pro soybean meal, rapeseed meal, rapeseed meal that has been saccharified and alcohol-fermented, bran, oats, milk casein, whey, fish meal, various vitamins, vitamin mixes, mineral mixes, amino acid preparations, calcium carbonate, monocalcium phosphate, vegetable oils and fats, animal oils and fats, and salt. When the total amount of the feed is taken as 100% by mass, the content of high protein soybean meal in the feed is preferably 0.1 to 30% by mass, more preferably 0.5 to 20% by mass, and even more preferably 1 to 10% by mass. Furthermore, for example, when using plant meal as a protein source as a feed ingredient, the high-protein soybean meal obtained by the production method of the present invention can be used as is, but it is also possible to use a mixture of high-protein soybean meal with protein sources such as ordinary soybean meal, hyper-soybean meal, rapeseed meal, rapeseed meal that has been saccharified and alcohol fermented, etc. Feed containing high-protein soybean meal can be produced by mixing the high-protein soybean meal produced by the production method of the present invention with the various feed ingredients and feed additives described above. Mixing can be carried out using a mixer such as a ribbon mixer, V-type mixer, or W-type mixer.

[0018] In order to explain the present invention more specifically, examples are shown below, but the present invention is not limited to these examples.

[0019] <Soybean meal used in the experiment> In this experiment, two types of soybean meal were used: regular soybean meal and hyper-protein soybean meal, which has a higher crude protein content than regular soybean meal. The component analysis values ​​of the soybean meal used are shown in Table 1.

[0020] [Table 1]

[0021] Example 1: Solid-state fermentation of soybean meal (small-scale test) 100 g of soybean meal or hyperpro soybean meal (dry weight) was placed in a reaction vessel, and 0.1% by mass of each of the fiber-degrading enzymes (cellulases) shown in Table 2 was added, followed by the addition of a suspension of yeast (Saccharomyces cerevisiae NBRC-0203) so that the total reaction system had an OD of 0.1. Water was then added so that the moisture content of the total reaction system was 50% by mass, yielding approximately 200 g of a mixture of soybean meal or hyperpro soybean meal and water. These were subjected to solid fermentation at 37°C for 7 days without autoclave sterilization. The yeast used (Saccharomyces cerevisiae) was Saccharomyces cerevisiae NBRC-0203, which can be obtained by distribution from the depository of the National Institute of Technology and Evaluation (NBRC). After 3 and 7 days, the solid portion was collected and weighed, and the ethanol concentration in the solid portion was measured. To measure the ethanol concentration, an equal amount of water was added to the solid portion, centrifuged at 1500 rpm for 10 minutes, and the supernatant was collected. The mixture was then centrifuged at 15,000 rpm for 10 minutes, and the supernatant was collected and diluted 1000 times with water. The ethanol concentration was measured using an ethanol analysis kit (product name: The F-kit, sold by JK International Co., Ltd.). The results are shown in Table 3.

[0022] [Table 2]

[0023] [Table 3]

[0024] In Table 3, three types of enzymes were used as fiber-degrading enzymes, and sufficient ethanol concentrations were detected with all of them. In particular, Enzyme KM detected high values ​​in both soybean meal and hyper-pro soybean meal. Enzyme KM is an endoglucanase produced by microorganisms of the genus Acremonium, and we believe that its high β-glucosidase activity contributed to these good results. Therefore, we narrowed the fiber-degrading enzyme down to Enzyme KM, which is produced by microorganisms of the genus Acremonium, and conducted the following experiment.

[0025] Example 2: Evaluation of solid-state fermentation of soybean meal and high-protein soybean meal (medium-scale test) 1000 g of soybean meal or hyperpro soybean meal (dry weight) was placed in a reaction vessel, and 0.1% by mass of the enzyme KM shown in Table 2 was added, followed by the addition of a suspension of yeast (Saccharomyces cerevisiae NBRC-0203) so that the total reaction system had an OD of 0.1. Water was then added so that the water content of the total reaction system was 50% by mass, yielding approximately 2000 g of a mixture of soybean meal or hyperpro soybean meal and water. These were subjected to solid fermentation at 37°C for 7 days without autoclave sterilization. To analyze the various components of the obtained high-protein soybean meal, it was subjected to a reduced-pressure heating treatment (72°C, -0.1 MPa) for 8 hours. The dried high-protein soybean meal was then pulverized in a mill (Osaka Chemical Co., Ltd., "Absolute mill ABS-W") to obtain an analytical sample. Tables 4 and 5 show the amount of ethanol produced per 100 g of dry weight of soybean meal or high-protein soybean meal in the medium-scale test, the components of the soybean meal or high-protein soybean meal in the medium-scale test (moisture, crude protein, crude fat, crude ash, carbohydrates (crude fiber, soluble nitrogen-free substances)), and the ratio of the crude protein content to the carbohydrate content of the resulting high-protein soybean meal (crude protein content / carbohydrate content) when the ratio of the crude protein content to the carbohydrate content of the raw material soybean meal or high-protein soybean meal (crude protein content / carbohydrate content) is set at 100. The analytical values ​​for the contents of crude protein, crude fat, crude ash, and carbohydrates (crude fiber and soluble nitrogen-free substances) are the contents on a dry matter basis. The amount of ethanol produced per 100 g of soybean meal in dry weight was measured using the same analytical method as described in Example 1. The moisture content of the obtained high-protein soybean meal was determined by the atmospheric pressure heating drying method, crude protein by the Kjeldahl method, crude fat by the Soxhlet method, crude ash by the direct incineration method, crude fiber by the filtration method, and soluble nitrogen-free matter was calculated by subtracting the moisture, crude protein, crude fat, crude ash, and crude fiber from 100. Carbohydrates were calculated as the sum of crude fiber and soluble nitrogen-free matter.

[0026] [Table 4]

[0027] [Table 5]

[0028] Comparative Example 1: Solid-state fermentation of rapeseed meal (medium-scale test) Instead of soybean meal, 3000 g of rapeseed meal (dry weight) was placed in a reaction vessel, and 0.1% by mass of the enzyme KM shown in Table 2 was added. Then, a suspension of yeast (Saccharomyces cerevisiae NBRC-0203) was added so that the total reaction system had an OD of 0.1. Water was then added so that the water content of the total reaction system was 50% by mass, yielding approximately 6000 g of a mixture of rapeseed meal and water. These were subjected to solid fermentation at 37°C for 7 days without autoclave sterilization. The amount of ethanol produced per 100 g of dry weight rapeseed meal was measured using the same analytical method as described in Example 1. In addition, the analytical values ​​of each component of the rapeseed meal after fermentation and the ratio of crude protein content to carbohydrate content were measured using the same analytical method as described in Example 2. These analytical results are shown in Table 6.

[0029] [Table 6]

[0030] As can be seen from Tables 4 and 5, ethanol was produced so that the amount of ethanol produced per 100 g of dry weight soybean meal or hyper-pro soybean meal was 5.2 to 6.7 g. These results demonstrate that even in medium-scale tests, ethanol production equivalent to or greater than that in small-scale tests is possible. Furthermore, as can be seen from Tables 4 and 5, the crude protein content of soybean meal before and after fermentation increased from 50.03% by mass to 58.16% by mass, and the crude protein content of high-protein soybean meal increased from 54.31% by mass to 61.50% by mass. This indicates that the carbohydrates (crude fiber, soluble nitrogen-free substances (starch, sugars, etc.)) in soybean meal or high-protein soybean meal were converted into ethanol by fermentation, resulting in a relative increase in the crude protein content contained in soybean meal or high-protein soybean meal. On the other hand, the carbohydrate content of soybean meal before and after fermentation decreased from 40.61% by mass to 31.33% by mass, and the carbohydrate content of high-protein soybean meal decreased from 36.56% by mass to 28.67% by mass. This indicates that the carbohydrates (crude fiber, soluble nitrogen-free substances (starch, sugars, etc.)) in soybean meal and high-protein soybean meal were converted into ethanol by fermentation. Furthermore, when the ratio of crude protein content to carbohydrate content on the seventh day of fermentation was set at 100, the ratio of crude protein content to carbohydrate content in the high-protein soybean meal was 150.7 and 144.4 for the high-protein soybean meal. This is thought to be because the carbohydrates (crude fiber, soluble nitrogen-free substances (starch, sugars, etc.)) in the raw soybean meal were consumed during the saccharification and alcohol fermentation processes, resulting in a decrease in the amount of carbohydrates and an increase in the crude protein / carbohydrate ratio. Furthermore, when the ratio of crude protein content to carbohydrate content on the 7th day of fermentation was set to 100, the ratio of crude protein content to carbohydrate content of the rapeseed meal that had been saccharified and alcohol fermented was 126.8 (Table 6). When we looked at the analytical values ​​for carbohydrates (crude fiber, soluble non-nitrogenous substances (starch, sugars, etc.)), the raw soybean meal had 40.61% by mass, the raw high-protein soybean meal had 36.56% by mass, and the raw rapeseed meal had 46.00% by mass, all of which were higher than the other raw soybean meals. Therefore, the raw rapeseed meal has more carbohydrates (crude fiber, soluble non-nitrogenous substances (starch, sugars, etc.)) that can serve as a fermentation substrate, It was expected that more carbohydrates (crude fiber, soluble nitrogen-free matter (starch, sugars, etc.)) would be consumed than in the raw soybean meal, resulting in a higher protein content and a larger crude protein to carbohydrate ratio. However, contrary to expectations, the ratio of crude protein to carbohydrate content was higher when soybean meal, which has a low carbohydrate content (crude fiber and soluble non-nitrogenous substances (starch, sugars, etc.)), was used as the raw material. In other words, this was an unexpected result, considering that rapeseed meal has a higher carbohydrate content, which is the fermentation substrate, than soybean meal. This experiment showed that by using soybean meal or high-protein soybean meal as a raw material and performing saccharification and alcohol fermentation processes, the crude protein content can be increased more than when rapeseed meal is used as a raw material.

[0031] Example 3: Solid-state fermentation of soybean meal with varying amounts of fibrous enzymes (small-scale test) 100 g of soybean meal or hyperpro soybean meal (dry weight) was placed in a reaction vessel, and the enzyme KM shown in Table 2 was added in the range of 0.01 to 5.0 mass%, followed by the addition of a suspension of yeast (Saccharomyces cerevisiae NBRC-0203) so that the total reaction system had an OD of 0.1. Water was then added so that the water content of the total reaction system was 50 mass%, yielding approximately 200 g of a mixture of soybean meal or hyperpro soybean meal and water. These were subjected to solid fermentation at 37°C for 7 days without autoclave sterilization. The amount of ethanol produced per 100 g of soybean meal dry weight was measured using the same analytical method as described in Example 1. The results are shown in Table 7.

[0032] [Table 7]

[0033] The results in Table 7 show that the greater the amount of enzyme added, the greater the amount of ethanol produced per 100 g of soybean meal dry weight.

[0034] <Comparative Example 2: Test in which saccharification treatment and alcohol fermentation treatment were performed separately (small-scale test)> 100 g of soybean meal or hyperpro soybean meal (dry weight) was placed in a reaction vessel, and 0.1% by mass of the enzyme KM shown in Table 2 was added. Water was then added so that the total water content of the reaction system was 50% by mass, yielding approximately 200 g of a mixture of soybean meal or hyperpro soybean meal and water. These were subjected to saccharification treatment at 50°C for 3 days without autoclave sterilization. Then, a suspension of yeast (Saccharomyces cerevisiae NBRC-0203) was added so that the total reaction system had an OD of 0.1, and alcoholic fermentation was carried out at 37°C for 3 days. The amount of ethanol produced per 100 g of soybean meal dry weight was measured using the same analytical method as described in Example 1. The results are shown in Table 8.

[0035] [Table 8]

[0036] According to Table 4, saccharification was performed at 50°C, the optimum temperature for the enzyme KM, followed by fermentation, but the amount of ethanol produced was lower than the amount of ethanol produced in Example 1 shown in Table 3 (raw material soybean meal: 4.17 g, raw material hyperpro soybean meal: 4.05 g). This shows that parallel fermentation, in which saccharification and fermentation are performed simultaneously, is more efficient at producing ethanol than a method in which saccharification and fermentation are performed separately.

[0037] Example 4: Solid-state ethanol fermentation of soybean meal using various yeasts (small-scale test) 100 g of soybean meal or hyperpro soybean meal (dry weight) was placed in a reaction vessel, and 0.1% by mass of the enzyme KM shown in Table 2 was added, followed by the addition of a suspension of each yeast shown in Table 9 so that the total reaction system had an OD of 0.1. Water was then added so that the moisture content of the total reaction system was 50% by mass, yielding approximately 200 g of a mixture of soybean meal or hyperpro soybean meal and water. These were subjected to solid fermentation at 37°C for 7 days without autoclave sterilization. The amount of ethanol produced per 100 g of dry weight of soybean meal was measured using the same analytical method as described in Example 1. The results are shown in Table 9.

[0038] [Table 9]

[0039] [Table 10]

[0040] The results in Table 10 show that the same amount of ethanol was produced even when different yeast strains were used.

Claims

1. A method for producing high-protein soybean meal, comprising mixing soybean meal with water, subjecting the resulting mixture to saccharification and alcoholic fermentation, adding cellulase for the saccharification, and adding yeast for the alcoholic fermentation. However, the method is characterized in that the mixture of soybean meal and water is not sterilized before the saccharification treatment and / or alcoholic fermentation treatment, and the saccharification treatment and alcoholic fermentation treatment are carried out by solid fermentation.

2. The method according to claim 1, wherein the saccharification treatment and the alcoholic fermentation treatment are carried out in the same step at a temperature of 25 to 45°C.

3. 3. The method for producing high-protein soybean meal according to claim 1 or 2, characterized in that, when the ratio of the crude protein content to the carbohydrate content (crude protein content / carbohydrate content) of the raw soybean meal is taken as 100, the ratio of the crude protein content to the carbohydrate content (crude protein content / carbohydrate content) of the obtained high-protein soybean meal is 130 to 160.

4. 4. The method for producing high-protein soybean meal according to claim 1, wherein the amount of ethanol produced per 100 g of dry weight of soybean meal in the alcohol fermentation treatment is 3.5 to 10 g.

5. The method for producing high-protein soybean meal according to any one of claims 1 to 4, wherein the amount of water in the reaction system in which the saccharification treatment and the alcohol fermentation treatment are carried out is 40 to 60 mass%.

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