JP6788034B2 - Manufacturing method of raw materials for saccharification - Google Patents

Description

The present invention relates to a production method for obtaining a raw material for saccharification using grain dust as a raw material.
The present application claims priority based on Japanese Patent Application No. 2016-249982 filed in Japan on December 22, 2016, the contents of which are incorporated herein by reference.

As a method for producing a raw material for saccharification, for example, a method for separating and producing starch, which is a raw material for saccharification, by immersing grains in sulfite or alkali is known.

Patent Document 1 describes a method for producing starch, which is a raw material for saccharification, by immersing rice, corn, wheat, sorghum or millet as grains in an alkali.

Japanese Unexamined Patent Publication No. 2010-24208

Grains used in the production of starch include crushed grains and non-standard grains generated by impact during transportation, and in the production of starch, these crushed grains and non-standard grains are removed and carefully selected. Grains are used. At this time, the removed crushed grain grains and non-standard grain grains are not effectively used and are treated as feed or fertilizer.

However, crushed grain grains and non-standard grain grains (hereinafter referred to as grain dust) are generated in an amount of about 0.1% by mass to 10% by mass of the grain as a raw material, and the ratio of the raw material is small. For example, the amount generated per day is in units of tens to hundreds of tons. The grain dust contains 50% by mass or more of starch in the whole grain dust, and is treated as feed or fertilizer without effectively using a considerable amount of starch.

On the other hand, in order to make effective use of grain dust, it has been attempted to put the grain dust into a dip tank soaked in sulfite or alkali in the production of starch to extract and separate the starch, but the grain dust is poorly immersed or soaked. It causes clogging at the time of draining the liquid later, is not easy to use, requires a plurality of processing steps in order to effectively obtain starch, and increases the manufacturing cost.

An object of the present invention is to provide a method for producing a raw material for saccharification, which can easily and efficiently produce starch, which is a raw material for saccharification, from grain dust.

The method for producing a raw material for saccharification according to the present invention comprises a crushing step of crushing grain dust, a dipping step of immersing the crushed grain dust in a sulfite-containing dipping solution, and after the crushing step and the dipping step. It includes a protein removing step of removing protein from a sulfite-containing immersion liquid containing grain dust.

The inventors of the present application have discovered that grain dust contains almost no germ having a light specific gravity. Therefore, it has been found that the grain dust does not require a step of separating the germ from the sulfite-containing dipping solution containing the crushed grain dust and the grain dust after the dipping step in the method for producing the raw material for saccharification. According to the method for producing a raw material for saccharification of the present invention, grain dust is starch (starch) without requiring a step of separating germ from a sulfite-containing immersion liquid containing crushed grain dust and grain dust after a dipping step. Therefore, starch as a raw material for saccharification can be easily obtained from grain dust. Further, since the grain dust treated as feed or fertilizer can be effectively used as a raw material for saccharification, the raw material for saccharification can be produced at a low production cost.

In the method for producing a raw material for saccharification, in the crushing step, the grain dust may be crushed until the value of d50 of the median diameter of the grain diameter of the grain dust becomes 500 μm or less. According to this, in the dipping step, the contact between the crushed grain grains and the sulfurous acid-containing dipping solution can be increased, and starch as a raw material for saccharification can be efficiently obtained from the grain dust.

Further, in the method for producing a raw material for saccharification, the sulfurous acid-containing immersion liquid may contain sulfurous acid in an amount of 20 ppm to 2000 ppm based on the weight of water contained in the sulfite-containing immersion liquid. According to this, in the dipping step, the bond between the starch and the protein can be efficiently broken, and the starch can be obtained more efficiently from the grain dust.

Further, in the method for producing a raw material for saccharification, the sulfurous acid-containing immersion liquid may further contain lactic acid, and the lactic acid may be contained at 100 ppm to 10000 ppm with respect to the weight of water contained in the sulfurous acid-containing immersion liquid. .. According to this, the starch content (yield) can be increased in the dipping step.

Further, in the method for producing a raw material for saccharification, the temperature of the sulfurous acid-containing immersion liquid in the immersion step can be set to 45 ° C to 60 ° C. According to this, in the dipping step, the bond between the starch and the protein in the grain dust can be efficiently cleaved, so that the starch as a raw material for saccharification can be obtained more efficiently.

Further, in the method for producing a raw material for saccharification, in the dipping step, the grain dust crushed by a stirrer and the sulfite-containing immersion liquid can be agitated. According to this, even if the grain dust is finely crushed, the grain dust and the sulfurous acid-containing immersion liquid can be mixed and circulated without being separated.

Further, in the method for producing a raw material for saccharification, the grain dust can be assumed to be grain dust generated in the process of producing starch. According to this, the grain dust generated in the starch manufacturing process can be reused.

Further, in the method for producing a raw material for saccharification, the grain dust can be assumed to be grain dust generated in the cornstarch production process. According to this, since the starch content of the grain dust generated in the cornstarch manufacturing process is high, the grain dust can be efficiently reused.

The method for producing a raw material for saccharification according to the present invention is a method for producing a raw material for saccharification using grain dust as a raw material, and is a crushing step (a step of crushing the grain dust) and a dipping step (the grain dust contains sulfite). A step of immersing in a dipping solution), and a protein removing step may be included after the pulverization step and the dipping step.

According to the method for producing a raw material for saccharification of the present invention, grain dust can be obtained as starch without the need for a step of separating germ from a sulfite-containing dipping solution containing crushed grain dust and grain dust after a dipping step. Therefore, starch as a raw material for saccharification can be easily obtained from grain dust. Further, since the grain dust treated as feed or fertilizer can be effectively used as a raw material for saccharification, the raw material for saccharification can be produced at a low production cost.

It is a figure which shows the flow of the manufacturing method of the raw material for saccharification in embodiment of this invention.

Hereinafter, an embodiment of the present invention will be described. As shown in FIG. 1, the method for producing a saccharifying raw material of the present embodiment is a method for producing a saccharifying raw material using grain dust as a raw material, and is a crushing step (step of crushing grain dust) and a dipping step (a step of crushing grain dust). A step of immersing grain dust in a sulfite-containing dipping solution), and after a crushing step and a dipping step, a foreign matter removing step (a step of removing peel and fiber and sand, metal powder and other foreign matters) and protein removal It includes a step (a step of removing protein by a difference in specific gravity), a washing step (a step of further washing the protein with water), and a dehydration step if necessary. By omitting the dehydration step, the method for producing the raw material for saccharification can be made simpler. Further, in the embodiment, the crushing step is performed before the dipping step, but the crushing step before the dipping step may be omitted and the crushing step may be provided after the dipping step.

The grains that are the source of grain dust are not particularly limited, but rice, barley, hato wheat, millet, millet, millet, corn, wheat, millet, millet, sorghum, red beans, soybeans, soybeans, and peanuts. , Sasage, green beans, red beans, mung beans, sesame seeds, barley sesame seeds, soba, amaranthus, quinoa, etc. Among these, crushed grain grains made of rice, corn, wheat, sorghum, and millet, which are processed into a large amount of grain dust and are easily available, can be preferably used. In particular, crushed grain grains made of corn are used. Due to its high starch content, it can be used more favorably. The starch content varies depending on the grain transportation conditions and the like.

Grain dust includes crushed grain grains and non-standard grain grains. Grain dust is removed without being used in the grain selection process, which is a raw material for the production of starch. A shifter (sieve) is generally used in the process of selecting grains, which is a raw material for producing starch. Specifically, for example, in the case of corn, a sieve with a mesh size of 17 mm and a sieve with a mesh size of 3.5 mm are used, and what remains on the sieve with a mesh size of 3.5 mm is normal corn grain sizing, and on a sieve with a mesh size of 17 mm. Those remaining in the grain are non-standard grain grains, and those passing through a sieve having a mesh size of 3.5 mm are crushed grain grains. Crushed grain grains include crushed grains and stems other than seeds, which are generated by impact during transportation of grains, and because they are too fine, they are used in the grain selection process in starch production. , Was removed without being used. When fine grains such as crushed grains are contained in the raw material, the following phenomena occur. First, in the dipping step without using a stirrer, the grain is submerged in the sulfite-containing immersion liquid, but when the grain crushed grains are contained, the sulfite-containing immersion liquid is channeled in the raw material containing the grain crushed grains. The sulfite-containing immersion liquid enters only in a certain flow path generated in the raw material, and it becomes difficult to spread it throughout the grain, leading to poor immersion. Secondly, when the sulfurous acid-containing immersion liquid and the grain are separated after the immersion step, if the proportion of crushed grain grains is large, the flow path of the immersion liquid is restricted and the liquid is difficult to be discharged from the immersion tank. Thirdly, most of the crushed grain grains are discharged together with the sulfurous acid-containing immersion liquid when the sulfurous acid-containing immersion liquid is discharged from the immersion tank, and therefore cannot be used in the subsequent starch recovery step. The size of the crushed grain varies depending on the type of grain, and is, for example, less than 3.5 mm (corn), less than 2.0 mm (rice, millet), and less than 1.5 mm (sorghum, millet). Non-standard grain grains are non-standard grains of a certain size or larger, and are grains that have been removed without being used as grains that may deteriorate in quality in the grain selection process in starch production. is there. Most of the non-standard grain grains have a low starch content in the cob and stem, and are not sufficiently crushed in the coarse crushing and grinding steps following the dipping process following the dipping process, causing clogging of pipes and the like. In some cases. The size of non-standard grains varies depending on the type of grain, and is, for example, 6 mm or more (sorghum, millet), 10 mm or more (rice, millet), and 17 mm or more (corn). Grain dust consisting of crushed grain grains and non-standard grain grains is generated in an amount of about 0.1 to 10% by mass of the grain used as a raw material for producing starch, which is a small proportion of the total raw material, but for example, per day. Is generated in units of tens to hundreds of tons.
In the present embodiment, the sizes of crushed grain grains and non-standard grain grains are determined by whether or not they pass through a sieve of a specified mesh. For example, a sieve having a mesh size of 17 mm is used and remains without passing through the sieve. Grains are defined as non-standard grains with a size of 17 mm or more, a sieve with a mesh size of 3.5 mm is used, and grains that have passed through the sieve are defined as crushed grains with a size of 3.5 mm or less.

The inventors of the present application have discovered that grain dust contains almost no germ having a light specific gravity. The reason why the crushed grain of corn contains almost no germ is that the germ is composed of a relatively flexible tissue unlike the powdery tissue such as endosperm, so that the crushed grain becomes finer. It is possible that there are few things. The content of germ in the crushed grain grain used as the grain dust in the present embodiment is 0% by mass to 6% by mass with respect to the entire crushed grain grain. The reason why non-grain grains contain almost no germ is that most of them are cobs and stems and contain almost no corn granules or germ. The content of germ in non-standard grain grains used as grain dust in the present embodiment is 0% by mass to 6% by mass with respect to the total crushed grain grains. Therefore, it has been found that the grain dust does not require a step of separating the germ from the sulfite-containing dipping solution containing the crushed grain dust and the grain dust after the dipping step in the method for producing the raw material for saccharification. Therefore, as shown in FIG. 1, even if the grain dust is crushed in the crushing step before the dipping step, the germ is not crushed and dispersed, so that it is not necessary to consider the recovery of the germ and the grain. Since the dust can be finely pulverized, the starch can be separated easily and efficiently in the dipping step. Further, by finely pulverizing the grain dust and stirring it, the immersion efficiency is improved and the concentrations of sulfurous acid and lactic acid in the sulfurous acid-containing immersion liquid can be suppressed low, so that it is not necessary to remove the sulfite-containing immersion liquid after the immersion step. Therefore, it is possible to solve the clogging at the time of draining the sulfurous acid-containing immersion liquid after the conventional immersion step. Even if the pulverization step is incorporated after the dipping step, it does not cause any problem as a method for producing the raw material for saccharification, omitting the time and effort required for manufacturing.

The grain dust in the present embodiment may contain only crushed grain grains, may contain only non-standard grain grains, or may contain both crushed grain grains and non-standard grain grains. Even when the grain dust contains both crushed grain grains and non-standard grain grains, the ratio of crushed grain grains and non-standard grain grains is not particularly limited, but the ratio of crushed grain grains to the total grain dust may be large. preferable. Even when the grain dust contains only non-standard grains, the grain dust may contain other stems other than seeds.

The raw material for saccharification is an intermediate product in the manufacturing process of a saccharified product containing a large amount of starch. If the proportion of starch contained in the saccharification raw material is 93% by mass to 96% by mass with respect to the total weight (dry weight) of the saccharification raw material, it can be used as a raw material in the saccharification product manufacturing process. The higher the proportion of starch contained in the raw material for saccharification, the more preferable, but generally it is 99.9% by mass or less. The raw material for saccharification is hydrolyzed, and depending on the degree of hydrolysis, a saccharified product from a mixture of intermediate sugars to the final glucose can be obtained. Examples of saccharified products include starch syrup, high fructose corn syrup, fructose, and glucose. The raw material for saccharification in the present embodiment may contain one or more of proteins, fibers, ash and the like as impurities. Further, if the impurities contained in the saccharification raw material in the present embodiment are 4% by mass to 7% by mass, it can be used as a raw material in the saccharification product manufacturing process. Since impurities contained in the raw material are removed in the purification step after hydrolysis, a problem arises even if the raw material for saccharification contains impurities to the extent that no load is applied in the purification step as described above. It's not a thing.

The crushing step is a step of crushing grain dust, and crushes grain dust in a substantially dry state to 500 μm (median diameter) or less using a crusher. As the crusher, a crusher such as a roller mill or a pin mill can be used. In the present embodiment, "dry grain dust" is defined as having a water content of 12% by mass to 16% by mass with respect to the total mass of the grain dust. In addition, the amount of water contained in the grain dust in the present embodiment is measured by the following method. 5 g of grain dust is dried at 135 ° C. for 2 hours in an indirect heating type dryer. The difference between the weight of the grain dust before drying, which is 5 g, and the weight of the dried grain dust is defined as the amount of water contained in the grain dust. The particle size of the grain dust after crushing is preferably 1 μm to 500 μm (median diameter). This is because the grain dust can be agitated without being separated in the dipping step. If the particle size of the grain dust is less than 1 μm, it may be scattered around in the crushing process in the dry state. On the other hand, if the particle size of the grain dust exceeds 500 μm, the bond between the starch and the protein may be insufficiently cleaved in the dipping step. If the particle size of the grain dust is 1 μm or more, it is difficult to scatter around in the crushing process even in a dry state. When the particle size of the grain dust is 500 μm or less, the bond between the starch and the protein can be sufficiently cleaved in the dipping step. The particle size of the grain dust is more preferably 5 μm to 200 μm, and even more preferably 10 μm to 100 μm or less. The median diameter in this embodiment is a value of d50.
The median diameter of the grain dust of the present embodiment is measured by using a laser diffraction type particle size distribution measuring device.

In the present embodiment, the crushing step is performed before the dipping step, but the crushing step before the dipping step may be omitted and the crushing step may be provided after the dipping step. When the crushing step is performed before the dipping step, the above-mentioned crusher suitable for crushing grain dust which is approximately dry can be used, but when the crushing step is performed after the dipping step, it is wet. Use a crusher suitable for crushing the grain dust in the state (for example, a power mill, an entrator mill, etc.).

As described above, since the grain dust contains almost no germ, the step of separating the germ after the step of crushing the grain dust is not required. As a result, the saccharification raw material can be produced more easily than when the saccharification raw material is produced using a general grain raw material.

The dipping step is a step of dipping the grain dust in a sulfite-containing dipping solution, which can efficiently break the bond between the starch and the protein in the grain dust, and efficiently remove the starch from the grain dust. Can be separated. In addition, in this embodiment, sulfite contains sulfite, hyposulfite, pyrosulfite and their sodium salt, potassium salt, magnesium salt and calcium salt.

The sulfurous acid in the sulfurous acid-containing immersion liquid preferably contains 20 ppm to 2000 ppm with respect to the weight of water contained in the sulfurous acid-containing immersion liquid. This is because the bond between starch and protein in grain dust can be efficiently cleaved. If the amount of sulfurous acid in the sulfurous acid-containing immersion liquid is less than 20 ppm with respect to the weight of water contained in the sulfite-containing immersion liquid, the process time of the immersion step may be long and the production efficiency of the raw material for saccharification may be inferior. In addition, the produced raw material for saccharification may be inferior in algae-proof and antifungal properties. On the other hand, when the amount of sulfurous acid exceeds 2000 ppm with respect to the weight of water contained in the sulfurous acid-containing immersion liquid, the concentration of sulfurous acid is excessive and it is uneconomical. If the sulfite in the sulfite-containing immersion liquid is 20 ppm or more with respect to the weight of the water contained in the sulfite-containing immersion liquid, the step time of the immersion step is not too long, and the raw material for saccharification can be efficiently produced. The algae-proof and antifungal properties of the raw material for saccharification are also maintained. If the amount of sulfurous acid is 2000 ppm or less with respect to the weight of water contained in the sulfurous acid-containing immersion liquid, the raw material for saccharification can be economically produced. The sulfurous acid in the sulfurous acid-containing immersion liquid is more preferably 40 ppm to 1500 ppm, more preferably 50 ppm to 800 ppm, based on the weight of water contained in the sulfurous acid-containing immersion liquid.

The sulfurous acid-containing immersion liquid may further contain lactic acid. Lactic acid may be an acid or a salt. The amount of lactic acid in the sulfurous acid-containing immersion liquid is preferably 100 ppm to 10000 ppm based on the weight of water contained in the sulfurous acid-containing immersion liquid. This is because the starch content (yield) of the saccharification raw material produced by the method for producing the saccharification raw material of the present embodiment can be increased. If the amount of lactic acid in the sulfurous acid-containing immersion liquid is less than 100 ppm with respect to the weight of water contained in the sulfite-containing immersion liquid, the effect of increasing the starch content (yield) of the raw material for saccharification may be insufficient. On the other hand, if lactic acid exceeds 10000 ppm (1%) with respect to the weight of water contained in the sulfurous acid-containing immersion liquid, the protein removal of the produced raw material for saccharification may be insufficient. When the lactic acid in the sulfurous acid-containing immersion liquid is 100 ppm or more with respect to the weight of water contained in the sulfurous acid-containing immersion liquid, the starch content (yield) of the raw material for saccharification can be increased. When lactic acid is 10,000 ppm (1%) or less based on the weight of water contained in the sulfurous acid-containing immersion liquid, the protein of the produced raw material for saccharification can be sufficiently removed. Lactic acid in the sulfurous acid-containing immersion liquid is more preferably 500 ppm to 5000 ppm, still more preferably 1000 to 2000 ppm, based on the weight of water contained in the sulfurous acid-containing immersion liquid.

In the dipping step, the solid content of the grain dust in the mixture of the grain dust and the sulfurous acid-containing immersion liquid (also referred to as the mixture of the grain dust and the sulfite-containing immersion liquid) is the total mass of the mixture of the grain dust and the sulfite-containing immersion liquid. On the other hand, 10% by mass to 50% by mass is preferable. This is because the mixing efficiency of the grain dust and the sulfurous acid-containing immersion liquid is excellent. When the solid content of the grain dust is less than 10% by mass with respect to the mixture of the grain dust and the sulfite-containing immersion liquid, the starch yield of the saccharification raw material obtained by the method for producing the saccharification raw material becomes low, which is not preferable. On the other hand, when the solid content of the grain dust exceeds 50% by mass with respect to the mixture of the grain dust and the sulfurous acid-containing immersion liquid, the water content (sulfurous acid-containing immersion liquid) is small with respect to the amount of the grain dust, and the stirring by the stirrer is sufficient. It may not be possible. When the solid content of the grain dust is 10% by mass or more with respect to the mixture of the grain dust and the sulfite-containing immersion liquid, the starch yield of the saccharification raw material obtained by the method for producing the saccharification raw material is sufficient. If the solid content of the grain dust is 50% by mass or less with respect to the mixture of the grain dust and the sulfurous acid-containing immersion liquid, the mixture can be sufficiently stirred by the stirrer. The solid content of the grain dust is more preferably 20% by mass to 40% by mass, still more preferably 30% by mass to 35% by mass, based on the mixture of the grain dust and the sulfurous acid-containing immersion liquid.

The temperature of the sulfurous acid-containing immersion liquid in the immersion step is preferably 45 ° C to 60 ° C. Since the bond between starch and protein in grain dust can be efficiently cleaved, starch as a raw material for saccharification can be obtained more efficiently. If the temperature of the sulfurous acid-containing immersion liquid is less than 45 ° C., the bond between the starch and the protein in the grain dust may be insufficiently broken, and the bactericidal effect may be insufficient. .. On the other hand, when the temperature of the sulfurous acid-containing immersion liquid exceeds 60 ° C., the bond between the starch and the protein in the grain dust can be efficiently cut, but the starch may gelatinize, and the amount of heat is also considered. Is uneconomical. When the temperature of the sulfurous acid-containing immersion liquid is 45 ° C. or higher, the bond between the starch and the protein in the grain dust can be sufficiently cleaved, and a sufficient bactericidal effect can be obtained. When the temperature of the sulfurous acid-containing immersion liquid is 60 ° C. or lower, the bond between the starch and the protein in the grain dust can be efficiently cleaved, and gelatinization of the starch does not occur. The temperature of the sulfurous acid-containing immersion liquid is more preferably 50 ° C. to 55 ° C.

The mixing time of the grain dust and the sulfurous acid-containing immersion liquid in the dipping step is preferably 1 hour to 48 hours, although it depends on the temperature of the sulfite-containing immersion liquid and the sulfurous acid concentration. This is because the bond between starch and protein in grain dust can be efficiently cleaved. If the mixing time of the sulfurous acid-containing immersion liquid is less than 1 hour, the bond between the starch and the protein in the grain dust may be insufficiently broken. On the other hand, when the mixing time of the sulfurous acid-containing immersion liquid exceeds 48 hours, the bond between the starch and the protein in the grain dust can be efficiently broken, but the heating continues during the immersion step, so that the calorific value is considered. Is uneconomical. When the mixing time of the sulfurous acid-containing immersion liquid is 1 hour or more, the bond between the starch and the protein in the grain dust can be sufficiently cleaved. When the mixing time of the sulfurous acid-containing immersion liquid is 48 hours or less, the bond between the starch and the protein in the grain dust can be efficiently cleaved, which is economical from the viewpoint of calorific value. The mixing time of the sulfurous acid-containing immersion liquid is more preferably 2 hours to 24 hours, still more preferably 3 hours to 16 hours.

In the dipping step, it is preferable to use a reactor having a hot water (cold water) circulation jacket capable of keeping the temperature of the sulfurous acid-containing immersion liquid constant. Further, the reactor is preferably one that can be stirred by a stirrer. This is because even if the grain dust is finely crushed, the grain dust and the sulfurous acid-containing immersion liquid can be mixed and circulated without being separated. As the stirrer, it is preferable to use a shaft rotary stirrer such as a propeller type. This is because it is easy to cope with a change in the viscosity of the mixed solution of the grain dust and the sulfurous acid-containing immersion solution in the immersion step. The speed of stirring by the stirrer is preferably 200 to 300 rpm. When the stirring speed is 200 rpm or more, the grain dust does not settle, the immersion efficiency can be improved, and the grain dust can be used in the subsequent steps without leaving the grain dust in the reactor. When the stirring speed is 300 rpm or less, it is possible to suppress the occurrence of excessive power cost. A circulation type stirrer can also be used, but it is necessary to confirm in advance whether or not the circulation type stirrer can cope with the change in viscosity of the mixed solution in the dipping step.

As described above, since the grain dust contains almost no germ, the step of separating the germ after the dipping step is not required. As a result, the saccharification raw material can be produced more easily than when the saccharification raw material is produced using a general raw material.

The foreign matter removing step is a step of removing pericarp and fiber, sand, metal powder and other foreign matters from a mixed solution of grain dust and a sulfurous acid-containing immersion liquid. The foreign matter removing step can include at least one of a filtering step by a screen mesh and a removing step by centrifugation.

The filtration step by the screen mesh is a step of removing foreign matter having a certain diameter (opening diameter of the screen mesh) or more from the mixed solution by passing it through the screen mesh. Since the foreign matter having a size larger than the opening diameter of the screen mesh cannot pass through the screen mesh by the filtration step by the screen mesh, the mixed liquid of the grain dust and the sulfite-containing immersion liquid is obtained by removing these foreign matters. The screen mesh used in the filtration step using the screen mesh is preferably 500 mesh (opening 25 μm) to 60 mesh (opening 250 μm). This is because the foreign matter can be preferably removed. If the screen mesh is finer than 500 mesh, it takes time to pass through the screen mesh, which is not economical. On the other hand, if it is coarser than 60 mesh, the foreign matter removing performance will be inferior. If the screen mesh is 500 mesh or rougher, the time for the screen mesh to pass through is not too long and is economical. If it is 60 mesh or finer, the foreign matter removing performance is sufficient. The screen mesh in the present embodiment is more preferably 440 mesh (opening 32 μm) to 100 mesh (opening 150 μm), and even more preferably 390 mesh (opening 38 μm) to 200 mesh (opening 75 μm).

The removal step by centrifugation is a step of removing foreign substances having a higher specific gravity such as sand and metal from the mixed solution of grain dust and a sulfurous acid-containing immersion solution by centrifugation. Specifically, by using a centrifuge such as a degritting cyclone or a hydrocyclone, it is possible to remove foreign substances having a large specific gravity such as sand and metal from a mixed solution of grain dust and a sulfurous acid-containing immersion liquid.

The protein removal step is a step of removing protein from a mixed solution of grain dust and a sulfurous acid-containing immersion solution by a difference in specific gravity to leave starch. Specifically, the protein can be removed by using a centrifuge. Specifically, when a mixed solution of grain dust and a sulfurous acid-containing immersion liquid is put into a centrifuge, proteins having a light specific gravity flow into an overflow, and starch having a heavy specific gravity flows into an underflow, so that the protein is removed. be able to. As the centrifuge used in the protein removal step, a nozzle separator, a hydrocyclone, or the like can be used. At the lab level, proteins can also be removed by tableing. Tabling is a method in which a slight height difference is provided on the upper edge of a container filled with a mixture of grain dust and a sulfite-containing immersion liquid, and water is allowed to flow through the container, leaving heavy starch at the bottom of the container. , A method of removing the protein by flowing a light-weight protein from the upper edge of the container together with water.

The washing step is a step of further washing the precipitate containing starch that has undergone a protein removal step, if necessary, with water. For example, there is a method in which a plurality of hydrocyclones are connected, one of which is charged with a precipitate that has undergone a protein removal step, and the other is charged with water, and the starch is washed by a countercurrent method. By the washing step, proteins can be further removed from the precipitate, and other impurities such as proteins, fibers, and oils having a lower specific gravity than starch can also be removed.

The dehydration step is a step of removing water (moisture) from the precipitate that has undergone the washing step, and can be taken when necessary as a raw material for saccharification. The dehydration step can be performed by dehydration by filtration or centrifugation, followed by drying with an indirect heating type dryer or the like. By omitting the dehydration step, the method for producing the raw material for saccharification can be made simpler.

The proportion of protein contained in the saccharified raw material that has undergone the washing step or the dehydration step is preferably 0.3 to 0.8% by weight in terms of dry weight with respect to the dry weight of the saccharified raw material. When the protein is 0.8% by weight or less in dry weight with respect to the weight of the saccharified raw material, the load in the purification step after saccharification of the saccharified raw material is small. It is preferable that the proportion of protein contained in the saccharified raw material is small, but if the protein is 0.3% by weight or more in dry weight with respect to the dry weight of the saccharified raw material, the cost increases by increasing the amount of water in the washing step. Does not need.

As described above, the saccharification raw material can be obtained from the grain dust by the method for producing the saccharification raw material. The obtained raw material for saccharification contains starch as described above, and its dry weight is 93.0 to 99.9% by mass. The raw material for saccharification that has undergone the dehydration step is a powder, and the particle size thereof is 5 to 20 μm. However, as described above, the raw material for saccharification contains impurities other than starch. Since the process of saccharifying the saccharification raw material includes various purifications such as ion exchange, the starch of the saccharification raw material obtained by the method for producing the saccharification raw material removes impurities in the saccharification process. It will be slaughtered.

Hereinafter, the present invention will be described in more detail with reference to Examples. Examples 1 to 21 are lab-level examples, and Examples 22 to 24 are plant-level examples. As the grain dust, corn grain dust generated in the cornstarch manufacturing process of the Kinuura Plant of Japan Corn Starch Co., Ltd. was used. The grain dust is composed of crushed grain grains having a size of less than 3.5 mm (median diameter, d50) and non-standard grain grains having a size of 17 mm (median diameter, d50) or more.

(Examples 1 to 7)
In Examples 1 to 7, the dates for collecting grain dust generated in the cornstarch manufacturing process were randomly selected, and it was confirmed that there was no problem in using the grain dust as a raw material for saccharification depending on the state of the grain dust.

The raw material for saccharification of Example 1 was produced under the production conditions shown in Table 1. Specifically, first, 100 g of dried grain dust was crushed for 1 minute with a household mixer. The crushed grain dust was mixed with 200 ml of a sulfurous acid-containing immersion liquid (containing 5000 ppm of lactic acid and 500 ppm of sulfite with respect to water in the sulfurous acid-containing immersion liquid). The obtained mixed solution was placed in a stainless steel 1 L mug, and grain dust was immersed in the sulfite-containing immersion solution for 180 minutes while stirring in a water bath. The immersion temperature was 52 ° C., and the solid content of the grain dust was 33% by mass with respect to the mixture of the grain dust and the sulfurous acid-containing immersion liquid. Then, a mixture of grain dust and a sulfurous acid-containing immersion liquid was filtered through a screen mesh of 325 mesh (opening 45 μm) to remove foreign substances. The resulting mixture was poured onto a gutter placed at a slight tilt to remove the protein by leaving heavy starch in the gutter (tabling). The starch was then washed by pouring 500 ml of water over the starch remaining on the gutter. The starch remaining on the gutter was dried overnight to obtain a raw material for saccharification.
The dry weight of the obtained raw material for saccharification was measured as follows. The obtained raw material for saccharification was dried by heating at 135 ° C. for 2 hours using an indirect heating type dryer, and the weight of the obtained raw material for saccharification was measured.
The content of starch contained in the obtained raw material for saccharification was calculated by the following method. The obtained raw material for saccharification is all hydrolyzed to glucose using enzymes such as α-amylase and glucoamylase, and then the amount of reducing sugar is measured by the Ferring-Lehmann-Scholl method, and the value is added to the value at the time of hydrolysis. of H _{2 O} fraction was to obtain a correction to the starch weight.
Here, the amount of reducing sugar was measured by the Fehling-Lehmann-Scholl method by the following method. 1 g of the dried raw material for saccharification was weighed and the volume was adjusted to 250 mL to prepare a sample solution. 69.3 g of copper sulfate was dissolved in distilled water and the volume was adjusted to 1 L to prepare reagent a. 346 g of Rossell salt and 103 g of sodium hydroxide were dissolved in distilled water to make 1 L, which was used as reagent b. 10 mL each of reagent a and reagent b were collected in a 200 mL Erlenmeyer flask, and 10 mL of the sample solution and 20 mL of distilled water were added thereto to make a total volume of 50 mL. This was heated to start boiling within 3 minutes, boiled for exactly 2 minutes, then immediately submerged in running water and cooled to 25 ° C. Then, 10 mL of a 30 wt% potassium iodide aqueous solution and 10 mL of a 25 wt% sulfuric acid aqueous solution were added, titration was immediately started with 0.1 N sodium thiosulfate, and 2-3 drops of a 1% starch solution was added as an indicator near the end point. Then, titration was continued until the starch reaction disappeared, and the titration was set as the end point. Distilled water was used instead of the sample solution, and the same operation as above was performed, the sugar amount was calculated based on the difference in the titration constant and the coefficient of sodium thiosulfate, and the value was obtained from the sugar amount and the dilution ratio.
Table 2 shows the collection date of grain dust and the yield of starch. The starch yield was calculated as the ratio of the dry weight of the obtained starch to the dry weight of the grain dust.

The raw materials for saccharification of Examples 2 to 7 were produced in the same procedure as in Example 1 except that grain dust was collected on the collection dates shown in Table 2.

Looking at the results of Examples 1 to 7 shown in Table 2, the yield of starch (the content of starch contained in grain dust) was within the range of 54 to 73% by mass regardless of the collection date. , It was usable as a raw material for saccharification. Although not described in Examples, similar results were obtained with other grains, although the yield of starch was relatively low.

(Examples 8 to 12)
In Examples 8 to 12, the yield (content rate) of starch due to the difference in the immersion time in the immersion step was confirmed. The production conditions of the raw material for saccharification other than the immersion time in the immersion step were the same as in Example 1. The immersion time of each example was as shown in Table 3. The date of collecting grain dust was June 15, 2015. Table 3 shows the yield of starch (content of starch contained in grain dust) with respect to the immersion time.

From the results of Examples 8 to 12, it was confirmed that the longer the soaking time, the higher the yield (content rate) of starch, but it was confirmed that the longer the soaking time, the slower the yield growth. did it. It was confirmed that 3 to 16 hours was the most preferable.

(Examples 13 to 15)
In Examples 13 to 15, the ratio of the solid content of the grain dust in the mixture of the grain dust and the sulfurous acid-containing immersion liquid in the dipping step was changed. The ratio of the solid content of the grain dust in the mixture of the grain dust and the sulfurous acid-containing immersion liquid in each example was as shown in Table 4. The production conditions other than the solid content ratio in the dipping step were the same as in Example 1. The collection date of the grain dust was the same as in Example 8. Table 4 shows the yield of starch (the content of starch contained in the grain dust) with respect to the grain dust in each example.

When the solid content ratio of the grain dust in the mixture of the grain dust and the sulfurous acid-containing immersion liquid was in the range of 10.0 to 33.0%, the starch yield was 53% or more. Although not described in the examples, in the test example in which the solid content exceeded 50% by mass, the water content (sulfurous acid-containing immersion liquid) was small with respect to the amount of grain dust, and stirring with a stirrer was sufficient. There wasn't.

(Examples 16 to 21)
In Examples 16 to 21, the contents of sulfurous acid and lactic acid in the sulfurous acid-containing immersion liquid in the immersion step were changed. The contents of sulfurous acid and lactic acid in the sulfurous acid-containing immersion liquid in each example were as shown in Table 5. The production conditions other than the contents of sulfurous acid and lactic acid in the dipping step were the same as in Example 1. The collection date of the grain dust was the same as in Example 8. Table 5 shows the yield of starch (the content of starch contained in the grain dust) with respect to the grain dust in each example.

In the range of the sulfurous acid content of the sulfurous acid-containing immersion liquids in Examples 16 to 21, no significant change was observed in the yield of starch with respect to grain dust due to the increase or decrease in sulfurous acid. From the viewpoint of antibacterial properties, sulfurous acid required to be 500 ppm or more when no other additive was added. For the evaluation of antibacterial properties, both the sulfite-containing immersion liquid and the mixture immediately after mixing and the mixture after immersion for 180 minutes were cultured in a film medium at 30 ° C. for 24 hours, and the difference in the number of colonies was 10% or less. If so, it was judged that there was no problem with antibacterial properties. In addition, it was confirmed that the yield of starch with respect to grain dust increased by increasing the lactic acid content of the sulfurous acid-containing immersion liquid. Although the description of the evaluation is omitted, when the amount of lactic acid exceeds 7,000 ppm with respect to the water contained in the sulfurous acid-containing immersion liquid, the removal of protein from the raw material for saccharification tends to be poor.

(Examples 22 to 24)
In Examples 22 to 24, the yield of starch when the raw material for saccharification was produced by a plant-level production method was confirmed. The raw material for saccharification was produced under the production conditions shown in Table 6.

The raw material for saccharification of Example 22 was produced as follows. First, 28 kg of dried grain dust was crushed with a pin mill (manufactured by Mutual Industry Co., Ltd.). The crushed grain dust was mixed with 56 L of a sulfurous acid-containing immersion liquid (containing 1500 ppm of lactic acid and 500 ppm of sulfite with respect to water in the sulfurous acid-containing immersion liquid), and immersed for 240 minutes while stirring in a tank equipped with a stirrer. .. The immersion temperature was 52 ° C., and the solid content of the grain dust was 33% by mass with respect to the mixture of the grain dust and the sulfurous acid-containing immersion liquid. Then, a mixture of grain dust and a sulfurous acid-containing immersion liquid was filtered through a screen mesh of a 325 ° DSM screen (manufactured by OLR-OLIVER) to remove foreign substances. The protein was removed by centrifuging the resulting mixture with a hydrocyclone (manufactured by DORR-OLIVER). The obtained precipitate was washed multiple times by centrifuging with 20 L of water for one wash with a hydrocyclone (manufactured by OLR-OLIVER). Table 7 shows the amount of grain dust used, the number of washings (the number of times the hydrocyclone shown in Table 6 is passed), the starch yield, and the protein content in each example. The protein content of the obtained raw material for saccharification was measured by the Kjeldahl method. Since the yield of starch with respect to the grain dust obtained in Examples 22 to 24 is 50% by mass or more, it is possible to produce a raw material for saccharification using grain dust as a raw material even at the plant level. Was confirmed.

The method for producing a raw material for saccharification according to the present invention can easily and efficiently produce a raw material for saccharification from grain dust.

Claims (8)

A crushing process that crushes grain dust and
A dipping step of immersing the crushed grain dust in a sulfurous acid-containing dipping solution, and
A method for producing a raw material for saccharification, which comprises a protein removing step of removing protein from a sulfite-containing immersion liquid containing grain dust after the crushing step and the dipping step. The method for producing a raw material for saccharification according to claim 1, wherein in the crushing step, the grain dust is crushed until the value of d50 of the median diameter of the grain diameter of the grain dust becomes 500 μm or less. The method for producing a raw material for saccharification according to claim 1 or 2, wherein the sulfurous acid-containing immersion liquid contains 20 ppm to 2000 ppm of sulfurous acid with respect to the weight of water contained in the sulfite-containing immersion liquid. The raw material for saccharification according to any one of claims 1 to 3, wherein the sulfurous acid-containing immersion liquid further contains lactic acid, and the lactic acid is contained at 100 ppm to 10000 ppm with respect to the weight of water contained in the sulfurous acid-containing immersion liquid. Production method. The method for producing a raw material for saccharification according to any one of claims 1 to 4, wherein the temperature of the sulfurous acid-containing immersion liquid in the immersion step is 45 ° C to 60 ° C. The method for producing a raw material for saccharification according to any one of claims 1 to 5, wherein in the dipping step, the grain dust crushed by a stirrer and the sulfite-containing immersion liquid are agitated. The method for producing a raw material for saccharification according to any one of claims 1 to 6, wherein the grain dust is grain dust generated in the process of producing starch. The method for producing a raw material for saccharification according to claim 7, wherein the grain dust is grain dust generated in the cornstarch production process.

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