Producing method of rice powder and device for production

Abstract

To provide a producing method of rice flour in which a sewage treatment apparatus is unnecessary, and, by increasing a water retention amount for holding moisture on an entire raw material rice and immersing moisture over entire raw rice to shorten a tempering time for permeating the moisture all over entire raw rice and an apparatus therefor.SOLUTION: A producing method of rice flour includes a coarse milling process that coarsely grinds the raw rice, a crack generation process that creates fine cracks in the water-impermeable layer of the coarsely milled raw rice due to the coarse milling process, a water addition process that adds moisture to the coarsely milled raw rice that has been cracked by the coarse milling and crack generation processes, a tempering process that allows the moisture added to the raw rice by the water addition process to permeate and equalize the moisture content, and a fine milling process that finely grinds the raw rice whose moisture content has been equalized by the tempering process.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a method and an apparatus for producing rice flour. [Background technology]

[0002] Conventionally, the following rice flour production methods and rice flour production systems have been known.

[0003] Patent Document 1 discloses a rice flour production system that produces rice flour by finely grinding raw material rice, either brown rice or polished rice. This rice flour production system X is characterized by including a washing device R that washes the raw material rice with water, a moisture adjustment device S that adjusts the moisture of the washed raw material rice, a coarse crushing device T that coarsely crushes the moisture-adjusted raw material rice to produce coarsely crushed rice, a hydration device U that adds water to the coarsely crushed rice, a tempering device V that permeates water into the coarsely crushed rice to adjust the moisture, and a fine grinding device W that finely grinds the coarsely crushed rice with the moisture content adjusted (see FIG. 7).

[0004] Since brown rice is covered with an outer husk (bran = pericarp, seed coat and aleurone layer) (see FIG. 8(a)), even if brown rice is soaked in water or water is added to the brown rice, the water does not penetrate to the core of the brown rice in a short time, and it takes a long time (15 to 16 hours) to penetrate the water. To solve this problem, Patent Document 1 uses a coarse crushing device T to coarsely crush the brown rice (divide it into 2 to 4 parts) (see FIG. 8(b)), and forms a fractured surface of the coarsely crushed brown rice that is not covered with the outer husk (bran) (coarse crushing process). Then, when water is added to the fractured surfaces of the coarsely crushed brown rice by a water adding device U (see FIG. 8(c)), the water adheres to the fractured surfaces of the coarsely crushed brown rice (water adding process). Furthermore, water penetrates the hydrated coarsely crushed brown rice through the fracture surfaces, and by maturing it in this state and adjusting the moisture content (see (d) in Figure 8), the coarsely crushed brown rice reaches the desired moisture content (around 30%) (tempering process).

[0005] As described above, by crushing brown rice, it is possible to bring the rice to a saturated moisture content (around 30%) in a short time, and rice flour (brown rice flour) can be produced efficiently. In particular, by using wet crushing, which allows moisture to penetrate the brown rice, the coarsely crushed brown rice with a moisture content of around 30% is finely crushed, so there is little damage to the starch layer. Because the brown rice is crushed coarsely, damage to the starch layer can be reduced.

[0006] Secondly, since the brown rice is washed with water before being crushed, contaminants such as soil bacteria and soil adhering to the brown rice can be removed, making it hygienic (washing process). Thirdly, after the brown rice is washed with water, the moisture content of the brown rice is adjusted, which makes it possible to prevent the coarsely crushed brown rice from becoming powdery or gelatinous during the coarse crushing process (moisture adjustment process, coarse crushing process). [Prior art documents] [Patent documents]

[0007] [Patent Document 1] JP 2012-50378 A Summary of the Invention [Problem to be solved by the invention]

[0008] However, in the above technology, the raw rice is washed with water in the washing device R before being crushed by the crushing device T, which requires the use of a large amount of water for washing. This necessitates the need for wastewater treatment facilities for the wastewater after the water washing, which increases production costs and the energy costs associated with the wastewater treatment.

[0009] In addition, in the above Patent Document 1, moisture can be penetrated through the fractured surfaces of the coarsely crushed brown rice, but the surface of the brown rice other than the fractured surfaces is covered with an outer husk (bran) through which moisture cannot easily penetrate. As a result, the moisture retention capacity of the raw brown rice near the outer husk (bran) is insufficient, and when viewed as a whole grain of brown rice, there is an uneven distribution of the moisture amount, so that the tempering time using the tempering device V to penetrate (distribute) the moisture throughout the raw rice tends to be long.

[0010] In consideration of the above problems, the present invention has as its technical object to provide a rice flour production method and apparatus that does not require wastewater treatment equipment, increases the water retention capacity of the raw material rice, and shortens the tempering time required for permeating water throughout the raw material rice. [Means for solving the problem]

[0011] In order to solve the above problems, the present invention provides a method for producing rice flour, which is characterized by comprising a coarse breaking step of coarsely breaking raw rice (brown rice, polished rice, no-rinse rice, etc.), a crack generating step of generating fine cracks in a layer of the raw rice coarsely broken by the coarse breaking step that is difficult for water to penetrate, a hydration step of adding moisture to the raw rice that has been coarsely broken by the coarse breaking step and that has generated cracks, a tempering step of allowing the moisture to penetrate the raw rice to which moisture has been added by the hydration step, thereby making the moisture content uniform, and a fine grinding step of finely grinding the raw rice whose moisture content has been made uniform by the tempering step.

[0012] In the invention described in claim 2, a sieving process for sieving the coarsely broken raw rice is provided between the coarse breaking process and the crack forming process, and the coarsely broken grains sieved out in the sieving process are carried to the crack forming process, and the fine grains sieved out in the sieving process are carried out to the water adding process, and different processing is carried out depending on the grain size of the raw rice sieved out in the sieving process.This is the method for producing rice flour described in claim 1. Effect of the Invention

[0013] According to the present invention, the process includes a coarse-breaking step of coarsely breaking raw rice, a crack-forming step of generating fine cracks in a layer of the raw rice that has been coarsely broken by the coarse-breaking step and that has generated cracks through it, a hydration step of adding moisture to the raw rice that has been coarsely broken by the coarse-breaking step and that has generated cracks through it, a tempering step of allowing the moisture in the raw rice to which moisture has been added by the hydration step to penetrate and make the moisture content uniform, and a fine grinding step of finely grinding the raw rice whose moisture content has been made uniform by the tempering step.In the coarse-breaking step, the raw rice that serves as the raw material is coarsely broken into 2 to 4 pieces, and then, in the crack-forming step, a large number of fine cracks are generated in the parts of the surface layer of the coarsely broken raw rice that are difficult for moisture to penetrate, and further, in the hydration step, moisture is added to the raw rice that has been coarsely broken and that has generated a large number of fine cracks on its surface, and the moisture seeps in and is absorbed through the fracture surfaces of the raw rice generated in the coarse-breaking step as well as through the large number of fine cracks generated in the crack-forming step. In other words, the two water pathways at the fracture surfaces and cracks allow water to be quickly absorbed into the starch layer in the center.

[0014] In addition, the cracks created by the crack formation process create paths for moisture, which increases the amount of moisture retained throughout the raw rice. This makes it possible to shorten the tempering time required for moisture to penetrate the entire raw rice. Furthermore, because the starch layer of the raw rice has absorbed moisture sufficiently, it is not necessary to provide an initial water washing process, and there is no need to install wastewater treatment equipment.

[0015] In addition, as in claim 2, if a screening process for screening the coarsely-broken raw rice is provided between the coarse-breaking process and the crack-forming process, and the coarsely-broken grains screened out in the screening process are carried into the crack-forming process, and the fine grains screened out in the screening process are carried into the water-adding process, and different treatments are performed according to the grain size of the raw rice screened out in the screening process, it is possible to design the capacity and capacity of the dryer used in the crack-forming process to be small, and the amount of heat and energy used in the crack-forming process can also be reduced. By providing such a screening process, there is an advantage in that the initial cost and running cost can be reduced by performing different treatments according to grain size. [Brief description of the drawings]

[0016] [Figure 1] FIG. 1 is a process diagram illustrating an outline of a method for producing rice flour according to an embodiment of the present invention. [Diagram 2] FIG. 2 is a process diagram illustrating an outline of a method for producing rice flour according to another embodiment of the present invention. [Diagram 3] FIG. 3 is a schematic diagram showing a production apparatus for carrying out the production method shown in FIGS. 1 and 2. [Figure 4] FIG. 2 is a perspective view showing the peripheral surface shape of each of a pair of crushing rolls. [Diagram 5] FIG. 1 is a schematic diagram showing the state of raw brown rice in the rice flour production method of the present invention. [Figure 6] FIG. [Figure 7] FIG. 1 is a schematic diagram showing a conventional rice flour production system. [Figure 8] FIG. 1 is a schematic diagram showing the state of raw brown rice in a conventional rice flour production method. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0017] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. Note that the following description of the embodiments is merely an example in nature.

[0018] FIG. 1 is a process diagram outlining a method for producing rice flour according to an embodiment of the present invention, FIG. 2 is a process diagram outlining a method for producing rice flour according to another embodiment of the present invention, and FIG. 3 is a schematic diagram showing a production apparatus for carrying out the methods shown in FIGS. 1 and 2. As shown in Figure 1, the rice flour manufacturing method of this embodiment uses brown rice, polished rice, or rinse-free rice as raw material rice and finely grinds it to produce rice flour. The rice flour manufacturing method of the present invention does not require a water washing step or a soaking step as is done when cooking rice, but employs a wet grinding method in which the rice is finely ground after sufficient water absorption into the starch layer.

[0019] In other words, the present invention does not employ the conventional washing and soaking processes in which raw rice is placed in a container filled with water and completely soaked, a process known as "deep-water soaking." This eliminates the need for wastewater treatment facilities for the wastewater generated in the washing and soaking processes, and also makes it possible to significantly reduce the amount of water used when adding water to the raw rice.

[0020] In Fig. 1, first, raw material rice (e.g., brown rice with a moisture content of 14%) is supplied to a coarse-breaking process (step 1 in Fig. 1, reference numeral 2 in Fig. 3). The coarse-breaking process is a process in which the raw material rice is roughly broken into 2 to 4 portions to produce coarsely broken raw material rice. The coarse-breaking device 2 used in the coarse-breaking process is configured to include, for example, a raw material rice input hopper 21, a grain lifter 22, a supply tank 23, and a coarse breaker 24, as shown in Fig. 3.

[0021] As shown in FIG. 3, the rough cutter 24 is formed by a pair of crushing rolls 2a and 2b like a flour mill roll machine. The pair of crushing rolls 2a and 2b are configured to face each other and rotate in different directions (rotating inwardly to bite the raw rice and roughly cut it) and at different peripheral speeds. The crushing rolls 2a and 2b are brake rolls with roll teeth as shown in FIG. 4 in order to roughly cut the brown rice, which is the raw rice, into 2 to 4 pieces. That is, the roll surface of one of the crushing rolls 2a has roll teeth made up of multiple grooves parallel to the axial direction of the rotating shaft, and the roll surface of the other crushing roll 2b has roll teeth made up of multiple grooves parallel to the circumferential direction (rotation direction) of the roll, forming a special combination of rolls. This reduces the risk that the raw rice caught in the gap between the pair of crushing rolls 2a and 2b will be finely crushed (finely pulverized), and increases the rate at which the raw rice is roughly cut into 2 to 4 pieces. As shown in FIG. 4, a special combination of the roll teeth of the crushing rolls 2a and 2b is suitable for roughly crushing the raw material rice.

[0022] A pressure-feeding ring blower 25 is provided below the coarse chopper 24 (see FIG. 3). The coarsely chopped raw material rice is transported upward by this pressure-feeding ring blower 25 through a pneumatic transport pipe 26. The raw material rice transported upward is then collected in a cyclone 27 and is kept on standby.

[0023] If necessary, a sifter 28 (see FIG. 3) for sifting the coarsely broken grains of raw rice is installed below the cyclone 27. If the amount of powdery grains is extremely small, there is no need to install this sifter 28.

[0024] In Fig. 1, the coarsely broken raw rice goes to the crack formation process (step 2 in Fig. 1, reference number 3 in Fig. 3), which is the process following the coarse breaking process. The crack formation process is a process in which fine cracks are generated in the surface layer of the raw rice, which has been roughly broken into 2 to 4 pieces and where moisture has difficulty penetrating. These fine cracks become pathways (conduits) for moisture to reach the starch layer in the center of the raw rice.

[0025] In the crack generation process, a heating device 3 is preferably used, which heats the roughly broken raw rice by blowing hot air or irradiating it with microwaves. The heating device 3 is, for example, configured to include a grain lifter 31, a supply tank 32, and a dryer 33, as shown in FIG.

[0026] As shown in Figure 3, the dryer 33 is composed of a grain flow path 34 formed by a porous wall 3a, an inlet 35 at the top of the grain flow path 34, an outlet 36 at the bottom of the grain flow path 34, a hot air supply section 37 that supplies air heated to 40 to 60°C across the grain flow path 34, and an exhaust section 38 that exhausts the hot air that has passed through the grain flow path 34 to the outside of the machine, and is in the form of a single-pass grain dryer.

[0027] In the dryer 33, air heated to 40-60°C is sent to the roughly broken raw rice for 5-10 minutes to dry it with hot air. This causes many fine cracks to form on the surface of the raw rice. At this time, the moisture content of the raw rice after drying is about 10-13%. Furthermore, if a microwave heating device 3 is used instead of the dryer 33, the raw rice can be rapidly heated to 100°C by irradiating the raw rice with microwaves for one minute, and many fine cracks form on the surface of the raw rice. At this time, the moisture content of the entire rice grain is also about 10-13%. On the surface of the raw rice, fine cracks shaped like tortoise shells or fish scales are formed, and these cracks become pathways (conduits) for moisture to reach the starch layer in the center of the raw rice.

[0028] In Figure 1, the raw rice with cracks formed therein proceeds to the hydration process (step 3 in Figure 1, reference number 4 in Figure 3), which is the process following the crack formation process. The hydration process is a process in which moisture is added to the raw rice that has been roughly broken and has fine cracks formed on its surface. In the hydration process, moisture is supplied via the fracture surfaces formed in the rough breaking process and the fine cracks formed in the crack formation process, and is absorbed into the starch layer in the center.

[0029] 3, the hydrating device 4 used in the hydrating step includes a grain lifter 41, a hydrating drum 42, an agitator blade 43 rotatably arranged inside the hydrating drum 42, a hydrating nozzle 44 arranged inside the hydrating drum 42, and a water tank 46 connected to the hydrating nozzle 44 via a pipe 45. A valve 47 is provided in the middle of the pipe 45 to control the flow rate of water.

[0030] The amount of water added is controlled so that the moisture content of the entire raw rice is 20-30%. Specifically, it is desirable to adopt a method in which fine water droplets are sprayed onto the surface of the raw rice using the hydration nozzle 44 in the hydration drum 42, and the moisture content is increased by the water adhering to the surface of the raw rice. By adding water using the hydration nozzle 44 and stirring using the stirring blade 43 for about 10-15 minutes, the moisture content of the entire raw rice can be controlled to reach 20-30%. This hydration process allows water to be absorbed through the fracture surfaces and fine cracks on the surface of the raw rice, all the way to the starch layer in the center. Another advantage is that the slow, gradual addition of water makes it difficult for moisture unevenness to occur between the surface and center of the raw rice.

[0031] In Figure 1, the hydrated raw rice goes to the tempering process (step 4 in Figure 1, reference number 5 in Figure 3), which is the process following the hydration process. The tempering process homogenizes the moisture in the hydrated raw rice. Tempering is also called "resting." This allows water to penetrate to the center of the raw rice, homogenizing the moisture. If the moisture cannot be homogenized, the quality of the rice flour will be poor in the final fine grinding process, and the quality of the rice flour will depend on whether or not there is a tempering process.

[0032] 3, the tempering device 5 used in the tempering step includes a conveyor tube 51, a screw 52 rotatably disposed within the conveyor tube 51, and the like. The tempering device 5 rotates the screw 52 to transport the hydrated raw material rice from the supply port 53 of the conveyor tube 51 to the discharge port 54. As a result, the water adhering to the surface of the hydrated raw material rice is absorbed through fine cracks into the starch layer in the center, and the raw material rice is conditioned to a moisture content of 20 to 30%, preferably around 28%, with no unevenness in the moisture content, and is discharged from the discharge port 54.

[0033] In FIG. 1, the tempered raw rice is sent to the final process, the fine grinding process (step 5 in FIG. 1, reference numeral 6 in FIG. 3). In the fine grinding process, the raw rice that has been through the processes of hydration and tempering is finely ground. At this time, it is preferable to use an airflow grinding device that suppresses impacts during grinding in order to minimize starch damage and produce fine rice flour. The airflow grinding device 6 used in the fine grinding process is composed of a fixed pin 62 fixedly arranged in a grinding chamber 61 and a rotating pin 62 rotatably arranged in the grinding chamber 61, as shown in FIG. 3, for example. The raw rice is put into the grinding chamber 61 of the airflow grinding device 6 and is finely ground by the rotating pins that rotate at high speed. At this time, an airflow is generated in the grinding chamber 61, and the rice is repeatedly impacted by the rotating pins due to the airflow, and is finely ground to produce rice flour. The finely ground rice flour is collected, dried to a predetermined moisture content, and returned to room temperature to prevent condensation, and then shipped to the market as a final product.

[0034] Next, the operation of the rice flour manufacturing method shown in Fig. 1 will be described with reference to Fig. 5 and Fig. 6. In the coarsely chopping process of step 1 in Fig. 1, raw material rice (for example, brown rice with a moisture content of 14%, Fig. 5(a)) is coarsely chopped into 2 to 4 portions (Fig. 5(b)). Next, in the crack generation process in step 2 in Fig. 1, many fine cracks K are generated in the surface layer of the roughly broken raw rice, where moisture has difficulty penetrating (Fig. 5(c)). These many fine cracks K become pathways (conduits) for moisture to reach the starch layer in the center of the raw rice. Furthermore, in the hydration process in step 3 in Figure 1, water is added to the raw rice that has been roughly broken and has many fine cracks formed on its surface (Figure 5(d)). At this time, water is absorbed by seeping in through the fracture surfaces of the raw rice that were created in the roughly breaking process, as well as through the many fine cracks K that were created in the crack formation process. The two water paths, the fracture surfaces and the cracks K, allow water to be quickly absorbed into the starch layer in the center.

[0035] Figure 6 is a graph confirming the water absorption characteristics (water absorption speed) due to differences in the treatment of raw rice. As shown in Figure 6, it was found that the water absorption characteristics of raw rice where cracks are formed after the raw rice is roughly broken (solid line = present invention) have a faster water absorption speed and a shorter time to reach saturated moisture compared to the water absorption characteristics of raw rice where the raw rice is roughly broken (dashed line = conventional technology).

[0036] In the tempering process in step 4 of Fig. 1, the raw rice is conditioned to have an even moisture content of 20-30%, preferably around 28%. In the fine grinding process in step 5 of Fig. 1, the raw rice is finely ground to produce rice flour.

[0037] <Another Example> As shown in FIG. 2, a rice flour manufacturing method according to another embodiment of the present invention is basically the same as the rice flour manufacturing method shown in FIG. 1, except that a sieving step (Step A) is provided between the coarse breaking step (Step 1) and the crack generating step (Step 2). In the sieving process (step A) in Fig. 2, the grains of raw material rice roughly broken in the coarse breaking process are sieved. As mentioned above, a coarse breaker 24 such as that shown in Fig. 4 reduces the risk of the raw material rice being broken down into small pieces (finely pulverized), and is suitable for roughly breaking the raw material rice, although some grains may be finely pulverized. By providing such a sieving process, different processing according to grain size can be carried out in the process following the coarse breaking process.

[0038] In the sieving step (step A) shown in Fig. 2, a sifter 28 shown by reference symbol 28 in Fig. 3 may be used. The sifter 28 is configured, for example, by stretching a sieve mesh 28b inside a housing 28a as shown in Fig. 3. The mesh width of the sieve mesh 28b may be, for example, 850 micrometers. As shown in Fig. 3, the housing 28a is provided with a path 28c for transporting coarsely broken particles that have passed through the sieve mesh 28b, and a path 28d for transporting fine particles that have passed through the sieve mesh 28b.

[0039] The coarsely broken grains that have passed through the sieve mesh 28b of the sifter 28 are supplied to the dryer 33 in the crack generation process via the path 28c and the lifting machine 31, while the fine grains that have passed through the sieve mesh 28b of the sifter 28 are supplied to the hydration drum 42 in the hydration process via the path 28d. In other words, in another embodiment of the present invention, not all of the raw rice roughly broken in the coarse breaking process is carried to the crack generation process. Some of the fine grains that are generated during the coarse breaking are carried directly to the hydration process, omitting the crack generation process. This makes it possible to design the capacity and capacity of the dryer 33 in the crack generation process to be small, and also reduces the amount of heat and energy used in the dryer 33. By providing such a sieving process, there is an advantage in that the initial cost and running cost can be reduced by performing separate processing according to the grain size.

[0040] As described above, according to the present invention, the method for producing rice flour includes a coarse-breaking step for coarsely breaking raw rice, a crack-forming step for generating fine cracks in the water-resistant layer of the raw rice coarsely broken by the coarse-breaking step, a hydration step for adding moisture to the raw rice that has been coarsely broken by the coarse-breaking step and the crack-forming step and that has generated cracks, a tempering step for allowing the moisture added by the hydration step to penetrate the raw rice to make the moisture content uniform, and a fine grinding step for finely grinding the raw rice whose moisture content has been made uniform by the tempering step. This does not require a wastewater treatment facility because it does not employ a washing step or a soaking step in which the raw rice is placed in a container filled with water and completely soaked, as in the conventional method. In addition, because fine cracks are generated in the water-resistant layer of the raw rice, the water retention capacity that holds moisture throughout the raw rice can be increased, and the tempering time for permeating the water throughout the raw rice can be shortened.

[0041] In addition, a sieving process is provided between the coarse breaking process and the crack formation process, in which the coarsely broken raw rice is sieved. The coarsely broken grains sieved in the sieving process are transported to the crack formation process, and the fine grains sieved in the sieving process are transported to the water addition process. Different processing is carried out depending on the grain size of the raw rice sieved in the sieving process, which has the advantage of reducing the initial costs and running costs in the crack formation process.

[0042] In addition, the coarse crushing device is a roll machine in which a pair of crushing rolls are opposed to each other and rotated in different directions and at different peripheral speeds. The peripheral surface of one of the crushing rolls has roll patterns consisting of multiple grooves parallel to the axial direction of the rotating shaft, while the peripheral surface of the other crushing roll has roll patterns consisting of multiple grooves parallel to the circumferential direction of the roll. This is a special combination of rolls, which reduces the risk of the raw material rice caught in the gap between the pair of crushing rolls being finely crushed (finely pulverized), and increases the proportion of the raw material rice that is roughly divided into 2 to 4 parts.

[0043] Furthermore, the heating device is composed of a grain flow path formed by a porous wall, an inlet at the top of the grain flow path, an outlet at the bottom of the grain flow path, a hot air supply section which feeds heated air across the grain flow path, and an exhaust section which exhausts the hot air that has passed through the grain flow path outside the machine.By drying the raw rice to a total moisture content of approximately 10-13%, it is possible to create fine cracks in the shape of a tortoise shell or fish scales on the surface of the raw rice. [Industrial Applicability]

[0044] The present invention is utilized in a method and an apparatus for producing rice flour obtained by finely grinding raw rice (brown rice, polished rice, rinse-free rice, etc.). [Explanation of symbols]

[0045] 1 Rice flour manufacturing equipment 2 Rough splitting device 3 Heating device 4 Water adding device 5 Tempering equipment 6. Airflow crushing device

Claims

1. The coarsely crushing process of the raw rice, A crack generating step of generating fine cracks in a layer of the raw rice that is coarsely broken by the coarse breaking step, which is difficult for water to penetrate; A hydration process for adding water to the raw material rice that has been roughly broken and has cracks formed therein by the rough breaking process and the crack forming process; a tempering process in which the moisture content of the raw material rice to which moisture has been added in the hydration process is made uniform by permeating the rice; and a fine grinding step of finely grinding the raw material rice whose moisture content has been made uniform by the tempering step.

2. The method for producing rice flour according to claim 1, characterized in that a sieving process for sieving the coarsely broken raw rice is provided between the coarse breaking process and the crack forming process, the coarsely broken grains sieved out in the sieving process are carried to the crack forming process, and the fine grains sieved out in the sieving process are carried out to the water adding process, and different processing is carried out depending on the grain size of the raw rice sieved out in the sieving process.

3. A coarsely chopping device for roughly chopping raw rice; A heating device that generates fine cracks on the surface layer of the raw material rice roughly broken by the rough breaking device; a hydration device that adds moisture to the raw material rice that has been roughly chopped by the rough chopping device and has fine cracks formed on its surface by the heating device; A tempering device that homogenizes the moisture of the raw material rice to which moisture has been added by the moisture adding device; and an airflow grinding device for finely grinding the raw rice tempered by the tempering device.

4. 4. The rice flour manufacturing apparatus according to claim 3, further comprising a sifter disposed between the coarsely breaking device and the heating device for sifting the raw rice coarsely broken by the coarsely breaking device into coarsely broken grains and fine grains.

5. 5. The rice flour production apparatus according to claim 3 or 4, wherein the coarse crushing device is a roll machine comprising a pair of crushing rolls opposed to each other and rotated in different directions and at different peripheral speeds, the peripheral surface of one of the crushing rolls having roll patterns made up of a plurality of grooves parallel to the axial direction of the rotating shaft, and the peripheral surface of the other crushing roll having roll patterns made up of a plurality of grooves parallel to the circumferential direction of the roll, forming a special combination of rolls.

6. 5. The rice flour production apparatus according to claim 3 or 4, wherein the heating device comprises a grain flow path formed by a porous wall, an inlet at an upper part of the grain flow path, an outlet at a lower part of the grain flow path, a hot air supplying section which supplies heated air across the grain flow path, and an exhaust section which exhausts the hot air that has passed through the grain flow path to the outside of the machine.

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