An invention relating to a jet mill for grinding grains and other materials into powder, and to the grain powder produced thereby.

Abstract

The present invention provides a jet mill that crushes grains or tea leaves into powder by the collision of compressed air ejected from a pair of nozzles, and the grain powder produced thereby. [Solution] A jet mill that crushes grains or tea leaves into powder by the collision of compressed air sprayed from a pair of nozzles. The pair of nozzles 2 are arranged on the same axis within a casing 3 that forms a grinding chamber. The compressed air supplied to the pair of nozzles is compressed by a compressor 4 and then cooled to at least room temperature by a cooling device 5. This compressed air is used to cause grains or tea leaves to collide with each other, thereby turning them into powder.

Description

Technical Field

[0001] One embodiment of the present invention relates to a jet mill for pulverizing grains or tea leaves into powder and the powder of grains or tea leaves produced thereby.

Background Art

[0002] Conventionally, there have been methods for producing powders of grains or tea leaves (see, for example, Patent Document 1 or Patent Document 2), and powders of barley green leaves and germinated seeds have been produced. For example, in Patent Document 1, a collision plate type jet mill is used, and the barley green leaf powder obtained thereby has rounded particles with corners removed, resulting in a smoother and rounder structure, which improves the dispersibility in water and makes it easier to swallow. However, when pulverizing barley green leaves into powder using a collision plate type jet mill, the barley green leaves are placed in a high-temperature state when colliding with the collision plate, so the nutrients originally possessed by the barley green leaves cannot be maintained as they are in the powder state.

[0003] For example, in Patent Document 2, for the purpose of not denaturing or decomposing functional components such as grains and beans during drying, a method of drying by aeration and pulverizing with a swirling airflow type pulverizer is described. In the invention described in Patent Document 2, when pulverizing grains and beans to be pulverized with a swirling airflow type pulverizer as a pulverizing device, the fluid is made into normal temperature compressed air to suppress heat generation during pulverization. However, there is no description of how much compressed air to use, and it is unclear how much heat generation during pulverization is actually suppressed.

[0004] Furthermore, what is common to Patent Document 1 and Patent Document 2 is that both target relatively easily pulverizable tea leaves and germinated seeds for pulverization, and grains covered with hard husks such as brown rice are not targeted for pulverization. Brown rice has a high nutritional value and unique umami components, and there is a need to use it in bread and noodles due to recent health trends, but it cannot be made into powder due to the hard husk of brown rice.

[0005] Furthermore, while bread and noodles are basically made by kneading wheat and water, there has been a growing demand in recent years for so-called gluten-free bread and noodles that do not contain gluten, which is produced during the manufacturing process. Gluten is a necessary sticky component for making bread and noodles, but it is difficult to break down with digestive enzymes and can cause allergic and inflammatory reactions, as well as disrupting the intestinal barrier function and causing abdominal bloating, abdominal pain, and diarrhea.

[0006] While the use of rice flour in bread and noodles has increased in recent years, bread and noodles made solely from rice flour have yet to be realized due to the need for a sticky component. [Prior art documents] [Patent Documents]

[0007] [Patent Document 1] Japanese Patent Publication No. 2021-136989 [Patent Document 2] Japanese Patent Publication No. 2003-334012 [Overview of the project] [Problems that the invention aims to solve]

[0008] The present invention aims to provide a jet mill device capable of grinding not only grains such as white rice, tea leaves, and dried foods that do not contain oil or sugar, but also brown rice, which has been difficult to grind using conventional methods. Furthermore, it aims to provide a jet mill device that can grind powders of, for example, 30 μm or less, and even 14 μm in median diameter, without destroying or maintaining nutrients before and after grinding. Moreover, it aims to provide a jet mill device that can grind not only grains such as white rice and tea leaves, but also brown rice, which has been difficult to grind using conventional methods, into powders smaller than 14 μm in median diameter, for example, 3 to 14 μm, without destroying or maintaining nutrients before and after grinding.

[0009] Furthermore, the goal is to enable the production of bread using rice flour or brown rice flour, which was previously impossible with rice flour alone, and to produce gluten-free bread and firm, chewy noodles despite being gluten-free. [Means for solving the problem]

[0010] To solve the above problems, the jet mill apparatus according to the present invention has a raw material supply port that receives raw materials from a pot containing grains (including brown rice) or dried foods that do not contain oil or sugar, a pair of nozzles arranged facing each other inside the casing, a compressor that generates compressed fluid to be supplied to the pair of nozzles, a cooling device that lowers the temperature of the fluid compressed by the compressor to room temperature, and piping that supplies the fluid compressed to room temperature output from the cooling device to each of the pair of nozzles.

[0011] The jet mill apparatus according to the present invention further includes a classifier. The classifier repeatedly grinds the powder until the particle size is within a predetermined range. For example, it uses classifier blades to eject coarse powder, which is greatly affected by the centrifugal force from the rotation, and returns it to the pot containing the raw grain.

[0012] The brown rice flour and rice flour produced by the present invention are, for example, powder particles of 30 μm or less, and even powder particles with a median diameter of approximately 14 μm, and even powder particles with a median diameter of 14 μm to 3 μm. Furthermore, the shape of the powder particles is not rounded, but rather has corners and recesses, and is characterized by a large surface area.

[0013] Therefore, when the powder according to the present invention is mixed with water, the powder according to the present invention retains water in its depressions and the gaps formed between the powder particles, resulting in a significantly larger water retention capacity compared to rounded powder particles. Consequently, dough made by mixing the powder according to the present invention with water is elastic, stretches well, and is sticky. This characteristic makes it possible to produce bread and firm noodles using only rice flour or brown rice flour, which was previously impossible with rice flour alone. [Brief explanation of the drawing]

[0014] [Figure 1] Schematic diagram of the jet mill device according to the present invention. [Figure 2] Measurement results of the particle size of rice flour produced from Akitakomachi using the jet mill device according to the present invention, measured with a scattering-type particle size distribution measuring device (Microtrac model MT3300EX). [Figure 3] Nozzle equipped with a dish for the powder to collide. [Figure 4] Measurement results of the particle size of rice flour produced from Corona brown rice using the jet mill device according to the present invention, measured with a scattering-type particle size distribution measuring device (Microtrac model MT3300EX). [Figure 5] SEM photograph of brown rice flour pulverized by the jet mill device according to the present invention. [Figure 6] SEM photograph of general rice flour. [Figure 7A] FE-SEM photograph of rice flour (average particle size 20 μm) pulverized by the jet mill device according to the present invention. [Figure 7B] Figure showing the positions of partial enlarged views (Figure 7C) and (Figure 7D) with squares. [Figure 7C] Image obtained by magnifying a part of Figure 7A by 2000 times. [Figure 7D] Image obtained by magnifying a part of Figure 7A by 10000 times. [Figure 8A] FE-SEM photograph of brown rice flour (average particle size 20 μm) pulverized by the jet mill device according to the present invention. [Figure 8B] Figure showing the positions of partial enlarged views (Figure 8C) and (Figure 8D) with squares. [Figure 8C] Image obtained by magnifying a part of Figure 8A by 2000 times. [Figure 8D] Image obtained by magnifying a part of Figure 8A by 10000 times. [Figure 9A] FE-SEM photograph of wet air-pulverized rice flour (manufactured by Tomizawa Shoten Co., Ltd., rice flour for bread made from Kyushu-grown rice (Mizuhotokara)). [Figure 9B] Figure showing the positions of partial enlarged views (Figure 9C) and (Figure 9D) with squares. [Figure 9C]An image of a portion of Figure 9A magnified 2000 times. [Figure 9D] An image of a portion of Figure 9A magnified 10,000 times. [Figure 10] This figure shows the measurement area of ​​ribs (white lines resembling ridges) in rice flour (average particle size 20 μm) pulverized by the jet mill device according to the present invention. [Figure 11] This figure shows the measurement area of ​​ribs (white lines resembling ridges) in brown rice flour (average particle size 20 μm) pulverized by the jet mill device according to the present invention. [Figure 12] This diagram shows the measurement area of ​​ribs (white lines resembling ridges) in wet-air-jet milled rice flour (manufactured by Tomizawa Shoten Co., Ltd., Kyushu-grown rice (Mizuho Chikara) rice flour for bread). [Figure 13] An image tracing the observed ribs (white lines resembling ridges) in the measurement area of ​​rice flour (average particle size 20 μm) pulverized by the jet mill device according to the present invention. [Figure 14] An image tracing the observed ribs (white lines resembling ridges) in the measurement area of ​​brown rice flour (average particle size 20 μm) pulverized by the jet mill device according to the present invention. [Figure 15] An image tracing the observed ribs (white lines resembling ridges) within the measurement area of ​​wet-air-jet milled rice flour (manufactured by Tomizawa Shoten Co., Ltd., Kyushu-grown rice (Mizuho Chikara) rice flour for bread). [Figure 16] Images showing the changes in the turbidity of each powdered tea after dissolving them in water and allowing them to become cloudy. [Figure 17] A diagram showing the temporal change in absorbance at a wavelength of 600 nm. [Modes for carrying out the invention]

[0015] The embodiments of the present invention will be described below with reference to the drawings and other materials. However, the present invention can be implemented in various forms without departing from its spirit, and is not to be interpreted as being limited to the embodiments described below.

[0016] While drawings may schematically represent the width, thickness, shape, etc., of each part compared to the actual embodiment in order to clarify the explanation, they are merely examples and do not limit the interpretation of the present invention.

[0017] The following description will focus on the jet mill apparatus according to the present invention (hereinafter also simply referred to as the jet mill apparatus) and the brown rice flour produced therefrom. However, the powder produced by the jet mill apparatus according to the present invention is not limited to brown rice flour.

[0018] Figure 1 is a schematic diagram of a jet mill apparatus according to the present invention. A pair of nozzles 2, arranged within a casing 3, are positioned coaxially. Compressed fluid generated by a compressor 4 is supplied to each of the nozzles 2. The compressed fluid is hot when generated by the compressor 4, but is cooled to room temperature by a cooling device 5 before being supplied to the pair of nozzles 2.

[0019] In the jet mill apparatus according to the present invention, raw materials such as brown rice and other grains, as well as tea leaves, are crushed by colliding them with the force of fluid ejected from a pair of coaxially arranged nozzles 2. Therefore, adjusting the flow rate and pressure of the fluid ejected from the nozzles 2 is an important parameter in producing powder. Theoretically, the larger the fluid flow rate and pressure, and the smaller the diameter of the nozzles 2, the higher the airflow, air pressure, and air velocity, resulting in greater force with which the raw materials collide, thus enabling the production of smaller powder particles more quickly. However, increasing the fluid flow rate and pressure increases the power consumption of the compressor 4, leading to increased production costs. On the other hand, insufficient fluid flow rate and pressure result in problems such as taking a long time to produce powder of a predetermined size.

[0020] In the jet mill apparatus according to the present invention, when grinding raw materials that are relatively easier to grind than brown rice, such as tea leaves or white rice, for example, if the diameter of the nozzle is 30 mm, the flow rate of the fluid sprayed from the nozzle 2 is 20 m³. 3The pressure is 6.2 kPa, and it is recommended to adjust the compressed air generated by compressor 4 to achieve this. This allows for the production of powder with a median diameter of 30 μm or less, for example, when measured by volume using a scattering particle size distribution analyzer (Microtrac model MT3300EX), while keeping costs relatively low.

[0021] Figure 2 shows the measurement results of the particle size of rice flour produced by grinding Akita Komachi rice using the jet mill device according to the present invention, measured using a scattering-type particle size distribution analyzer (Microtrac model MT3300EX). The specific surface area is 2618 cm². 2 ,cm 3 The median diameter is 32.818 μm, and the arithmetic mean diameter is 37.336098 μm. As shown in the graph in Figure 2, it can be seen that we were able to obtain powder with extremely small deviations and uniform size.

[0022] When grinding raw materials that are surrounded by a husk and are relatively difficult to grind, such as brown rice, for example, if the diameter of nozzle 2 is 30 mm, the flow rate of the fluid discharged from nozzle 2 is 20 m³. 3 The pressure is / min, and it is recommended to adjust the compressed air generated by compressor 4 to achieve an injection pressure of 7.3kPa. This allows for relatively low costs while producing powder with a median diameter of approximately 14μm, for example, when measured by volume using a scattering particle size distribution analyzer (Microtrac model MT3300EX).

[0023] In this invention, since the raw materials such as brown rice are crushed by using the force of the fluid ejected from a pair of coaxially arranged nozzles 2 to cause collisions between them, the finer the powder becomes, the lower the probability of collisions between the raw materials becomes. Therefore, the finer the powder is to be crushed, the more difficult it tends to be to crush it efficiently. To address this, the shape of the nozzles 2 may be such that, for example, as shown in Figure 3, it is equipped with a tray for the powder that does not collide with other raw materials to collide with.

[0024] The reason why brown rice is a relatively difficult raw material to grind is as follows: Generally, when producing rice flour, the rice is soaked in water before grinding. Rice is easy to grind because it absorbs water. On the other hand, brown rice is difficult to grind because its hull is hard and does not absorb water even when soaked in water. With the jet mill device according to the present invention, it is possible to grind even brown rice, which is difficult to grind, and thus brown rice flour can be produced.

[0025] Figure 4 shows the particle size of rice flour produced by grinding brown rice using the jet mill device according to the present invention, measured using a scattering particle size distribution analyzer (Microtrac model MT3300EX). The median diameter was 13.6991 μm, the mode diameter was 14.2071 μm, the arithmetic mean diameter was 14.7578 μm, and the arithmetic standard deviation was 6.7707 μm. Based on the arithmetic standard deviation and the shape of the graph shown in Figure 4, it can be seen that even with grains with hard husks, such as brown rice, it was possible to obtain powder with extremely small deviations and uniform particle size.

[0026] The cooling device 5 lowers the temperature of the fluid compressed by the compressor 4 to room temperature. As described above, the flow rate of the fluid discharged from the nozzle 2 is 20 m³. 3 When the injection pressure is set to 6.2kPa or 7.3kPa at a rate of / min, and the temperature of the compressed fluid is lowered to room temperature, the temperature of the fluid injected from nozzle 2 can be reduced to at least 0°C or below due to adiabatic expansion. Therefore, it is possible to powder the raw materials such as buckwheat, rice, and brown rice while maintaining their nutrients.

[0027] There are no particular restrictions on the classification method. Therefore, any classifier commonly used in the flour milling industry may be used as the classifier, for example, a method using air classification with centrifugal force generated by rotation. After classification, powder exceeding a predetermined size is returned to the pot 10 to be crushed again, and powder that falls within the predetermined size range is collected in the powder pot 7 as crushed powder.

[0028] Table 1 below compares the nutrients of brown rice and brown rice flour produced by the jet mill device according to the present invention. The nutritional analysis results for brown rice are the values ​​shown in the Japanese Food Standard Composition Table 2020 (8th Revised Edition) compiled by the Ministry of Education, Culture, Sports, Science and Technology. The nutritional data for brown rice flour is the result of analysis by the Japan Food Research Laboratories.

[0029] [Table 1]

[0030] The nutritional values ​​of brown rice shown in the 2020 edition (8th revised) of the Standard Tables of Food Composition in Japan published by the Ministry of Education, Culture, Sports, Science and Technology are merely standard values ​​and are based on the analysis results of brown rice different from the brown rice used as the raw material for the brown rice flour pulverized by the jet mill device according to the present invention. Therefore, due to differences in the raw material brown rice itself, as shown in Table 1, while some nutrients are found to be higher in the brown rice flour according to the present invention than in brown rice, it can be seen that there is almost no significant difference in nutrients between brown rice and the brown rice flour according to the present invention. This fact indicates that the brown rice flour pulverized by the jet mill device according to the present invention is powdered while maintaining almost all of the nutrients that the brown rice had. Therefore, it can be said that the brown rice flour according to the present invention has almost the same nutritional value as brown rice, and can be said to contain 0.8 mg or more of pantothenic acid and 25 μg or more of folic acid.

[0031] Thus, the reason why the brown rice flour pulverized by the jet mill device according to the present invention retains almost all of the nutrients it had as brown rice is, as mentioned above, because the temperature during pulverization is kept at least 0°C or below. By keeping the temperature during pulverization at least 0°C or below, the problem of thermal friction and thermal denaturation occurring due to the material being exposed to high temperatures during pulverization, which would result in the loss of nutrients, is avoided. Furthermore, pulverization by the jet mill device according to the present invention is performed by pulverizing from a pair of nozzles 2, for example, 20m 3Because the particles are crushed by colliding with each other while carried by a fluid injected at a flow rate of 6.2 kPa or 7.3 kPa per minute, the crushing occurs instantaneously. This instantaneous crushing is one of the reasons why the nutrients in the powder according to the present invention are not lost.

[0032] Regarding the shape of the brown rice flour pulverized by the jet mill device according to the present invention, its shape has a large surface area due to having a pointed tip or a concave part, and does not have a smooth surface. This is because the pulverization is carried out by the brown rice raw material colliding with each other while riding on a fluid.

[0033] Figure 5 is an SEM image of brown rice flour ground by the jet mill device according to the present invention. As can be seen, the image on the left side of Figure 5 appears as a relatively large clump because the powder has aggregated (the finer the powder, the more easily it aggregates). However, looking at the image on the right side of Figure 5, it can be observed that the brown rice flour has been finely ground into various shapes, such as elongated shapes with pointed ends and triangular shapes. Figure 6 is an SEM image of general rice flour. Compared to Figure 6, it can be clearly seen that the brown rice flour ground by the jet mill device according to the present invention has a shape with pointed ends.

[0034] Therefore, the brown rice flour pulverized by the jet mill device according to the present invention can easily retain water even on its own, and when aggregated as a powder, it can form gaps between the particles, allowing it to retain water in those gaps. When water is added until it reaches a predetermined growth rate and elasticity, the water retention capacity of conventional rice flour is 30% or less of the rice flour, whereas the rice flour pulverized by the jet mill device according to the present invention can retain more than 55% and up to 60% of the rice flour. The reason why rice flour, rather than brown rice flour, is used for comparison here is that brown rice flour pulverized to a degree suitable for use in bread dough, etc., can only be realized for the first time by the jet mill device according to the embodiment of the invention, and therefore there is no brown rice flour to compare it with. However, the brown rice flour pulverized by the jet mill device according to the present invention can also retain more than 55% and up to 60% of the brown rice flour.

[0035] The property of the buckwheat flour, rice flour, and brown rice flour ground by the jet mill device according to the present invention to easily retain moisture is useful in making foods that require stickiness like gluten, such as bread and noodles. With the buckwheat flour according to the present invention, it is possible to easily make 100% buckwheat noodles without using wheat flour as a binder. This is because buckwheat flour, rice flour, and brown rice flour that contain sufficient water have elasticity, stretch well, and stickiness similar to gluten-containing dough, even without gluten.

[0036] Dried noodles made from rice flour with added modified starch have existed for some time. However, it was previously almost impossible to manufacture dried noodles from brown rice flour. As mentioned above, brown rice flour is more difficult to grind than rice flour, and at best it can only be ground to an average particle size of about 100 μm. Brown rice flour with an average particle size of about 100 μm absorbs less moisture than rice flour, and the particles do not stick together, making it extremely difficult to use in processed foods such as dried noodles. However, the applicant was able to manufacture dried noodles using brown rice flour ground by the jet mill device according to the present patent invention.

[0037] The dried noodles made using the brown rice flour pulverized by the jet mill device according to this patent invention consist of 80% brown rice flour and 20% rice flour, with no added modified starch. These dried noodles can be manufactured with a thickness (diameter of cross-section) of 1 mm. Therefore, when manufacturing dried noodles for ramen using the brown rice flour pulverized by the jet mill device according to this patent invention, the thickness (diameter of cross-section) of the dried noodles is between 1 mm and 2 mm, preferably 1.6 mm. When manufacturing dried noodles for udon, the thickness (diameter of cross-section) is between 2 mm and 3 mm, preferably 2.5 mm. Regardless of the thickness, the dried noodles have a firm texture and can be used as dried noodles where firmness is required, such as ramen and somen.

[0038] Figure 7A is an FE-SEM image of rice flour (average particle size 20 μm) ground using the jet mill device according to the present invention. Figures 7C and 7D are magnified portions of Figure 7A, 2000x and 10000x, respectively. Figure 7B is a diagram showing the locations of magnified portions of Figures 7C and 7D using rectangles. Relatively larger rectangles indicate the region of Figure 7C, and relatively smaller rectangles indicate the region of Figure 7D. Note that the particle sizes in this experiment are median diameters obtained by measuring with a scattering particle size distribution analyzer (LA-300 scattering particle size distribution analyzer manufactured by Horiba, Ltd.). Figure 8A is an FE-SEM image of brown rice flour (average particle size 20 μm) ground using the jet mill device according to the present invention. Figures 8C and 8D are magnified portions of Figure 8A, 2000x and 10000x, respectively. These are magnified views at 00x and 10000x magnification. Figure 8B is a diagram showing the locations of the partially magnified views (Figure 8C) and (Figure 8D) with rectangles. Relatively larger rectangles indicate the area of ​​Figure 8C, and relatively smaller rectangles indicate the area of ​​Figure 8D. Figure 9A is an FE-SEM photograph of wet-air-jet milled rice flour (manufactured by Tomizawa Shoten Co., Ltd., Kyushu-grown rice (Mizuho Chikara) rice flour for bread), and Figures 9C and 9D are parts of Figure 9A at 2000x and 10000x magnification, respectively. Figure 9B is a diagram showing the locations of the partially magnified views (Figure 9C) and (Figure 9D) with rectangles. Relatively larger rectangles indicate the area of ​​Figure 9C, and relatively smaller rectangles indicate the area of ​​Figure 9D. Wet-air-jet milling is a conventional milling method used to manufacture rice flour.

[0039] The rice flour and brown rice flour pulverized by the jet mill device according to the present invention do not show any visible starch cells, and have more irregularities than rice flour pulverized by wet airflow. As is clear from comparing Figures 7D and 8D with Figure 9D, the surface of the rice flour and brown rice flour pulverized by the jet mill device according to the present invention has finer irregularities and visible corners compared to rice flour pulverized by wet airflow.

[0040] Based on enlarged views (Figures 7C, 8C, and 9C), the surface structures of rice flour particles pulverized by the jet mill device according to the present invention, brown rice flour particles pulverized by the jet mill device according to the present invention, and rice flour particles pulverized by wet airflow were analyzed using ImageJ, an image analysis software. For the analysis, eight 6 μm × 6 μm measurement areas were randomly selected within the enlarged views (Figures 7C, 8C, and 9C). Within these measurement areas, lines that appear as ribs in the image (lines that appear white like ridges) were considered to represent the surface irregularities of each powder, and the total length of these ribs (lines that appear white like ridges) was measured.

[0041] Figure 10 shows the measurement area of ​​ribs (white lines that appear like ridges) in rice flour (average particle size 20 μm) pulverized by the jet mill device according to the present invention, Figure 11 shows the measurement area of ​​ribs (white lines that appear like ridges) in brown rice flour (average particle size 20 μm) pulverized by the jet mill device according to the present invention, and Figure 12 shows the measurement area of ​​ribs (white lines that appear like ridges) in rice flour (manufactured by Tomizawa Shoten Co., Ltd., Kyushu-produced rice (Mizuhochikara) bread flour) that has been wet-flow pulverized.

[0042] Figure 13 is an image tracing the observed ribs (white lines resembling ridges) in the measurement area of ​​rice flour (average particle size 20 μm) pulverized by the jet mill device according to the present invention. Figure 14 is an image tracing the observed ribs (white lines resembling ridges) in the measurement area of ​​brown rice flour (average particle size 20 μm) pulverized by the jet mill device according to the present invention. Figure 15 is an image tracing the observed ribs (white lines resembling ridges) in the measurement area of ​​rice flour pulverized by wet airflow milling (manufactured by Tomizawa Shoten Co., Ltd., Kyushu-produced rice (Mizuho Chikara) bread flour).

[0043] Table 2 below summarizes the results obtained by tracing the ribs (white lines resembling ridges and crack edges) in each observation area of ​​rice flour (average particle size 20 μm) ground by the jet mill device according to the present invention, brown rice flour (average particle size 20 μm) ground by the jet mill device according to the present invention, and wet air-jet ground rice flour (manufactured by Tomizawa Shoten Co., Ltd., Kyushu-produced rice (Mizuho Chikara) bread flour) using "Analyze" - "Measure", and measuring them.

[0044] [Table 2]

[0045] According to Table 2, the average length of the ribs (white lines resembling ridges) in rice flour (average particle size 20 μm) ground using the jet mill device according to the present invention was 61.0 μm, and the average length of the ribs (white lines resembling ridges) in brown rice flour (average particle size 20 μm) ground using the jet mill device according to the present invention was 77.8 μm. On the other hand, the average length of the ribs (white lines resembling ridges) in rice flour ground using wet airflow milling (manufactured by Tomizawa Shoten Co., Ltd., Kyushu-produced rice (Mizuho Chikara) bread flour) was 50.5 μm. This experiment revealed that rice flour and brown rice flour ground using the jet mill device according to the present invention have more irregularities (ribs) formed on the surface of the powder compared to rice flour ground using wet airflow milling.

[0046] The irregularities (ribs) formed on the surface of the powder are thought to be a structure that makes it easier for the powder to retain moisture, and are thought to greatly affect the water retention capacity of the powder. It is thought that the rice flour, brown rice flour, or buckwheat flour ground by the jet mill device according to the present invention has an increased water retention capacity due to the irregularities (ribs) formed on the surface of the powder, which makes it possible to make foods that require stickiness such as gluten, such as bread and noodles. Therefore, although FE-SEM analysis has not been performed on the buckwheat flour ground by the jet mill device according to the present invention, it is thought that, like the rice flour and brown rice flour, a large number of irregularities (ribs) are formed on the surface compared to general buckwheat flour.

[0047] Figure 16 shows images illustrating the changes in turbidity over time, after preparing 0.25g each of the following powdered teas: tea leaves ground by the jet mill device according to the present invention (reference numeral (1) in Figure 16), "Oi Ocha" (registered trademark) manufactured by Ito En Co., Ltd. (reference numeral (2) in Figure 16), "Asahi Tea Industry" (powdered Uji tea) manufactured by MC Foods Co., Ltd. (reference numeral (3) in Figure 16), and "Asahi Tea Industry" powdered Chiran tea manufactured by MC Foods Co., Ltd. (reference numeral (4) in Figure 16). These were each added to a beaker containing 100ml of water, and after shaking each beaker well to make it turbid, the images show the changes in turbidity over time.

[0048] The first image shows the liquid immediately after turbidity, the second image shows it 10 minutes later, the third image shows it 20 minutes later, and the fourth image shows it 55 minutes later. As can be seen from these images, the tea leaves ground using the jet mill device according to the present invention show less color change and less sedimentation compared to powdered Uji tea and powdered Chiran tea. In addition, Oi Ocha (registered trademark) contains dextrin as a dispersion medium, so it shows less color change and less sedimentation. In the case of tea leaves ground using the jet mill device according to the present invention, even without containing dextrin as a dispersion medium, it can be said that the amount of sedimentation of the tea powder changes over time to a similar extent and the dispersed state can be maintained.

[0049] Changes in turbidity were confirmed not only visually but also by measuring absorbance, which represents how much light is absorbed when light of a specific wavelength passes through a substance, at 0, 5, 10, 20, and 30 minutes after turbidity was established. Figure 17 (Graph 1) shows the temporal change in absorbance at a wavelength of 600 nm. Table 2 summarizes the measurement results. In Figure 17, the tea leaves ground by the jet mill device according to the present invention are identified by "UMF".

[0050] [Table 3]

[0051] In Table 3, tea leaves ground using the jet mill device according to the present invention are identified by "UMF". As is clear from the absorbance measurements, it has been proven that in the case of tea leaves ground using the jet mill device according to the present invention, even without containing dextrin as a dispersion medium, the amount of settled tea powder over time changes to a similar extent, and the dispersed state can be maintained.

[0052] Although embodiments of the present invention have been described above, any jet mill apparatus based on the present invention, in which the company has added, deleted, or modified components, or added, omitted, or modified processes, is also included in the scope of the present invention, as long as it retains the gist of the present invention.

[0053] Any effects or benefits other than those brought about by the embodiments described above, if they are clear from the description herein or easily predictable by the business operator, are naturally considered to be brought about by the present invention. [Explanation of symbols]

[0054] 2: Nozzle, 3: Casing, 4: Compressor, 5: Cooling device, 6: Classifier, 7: Powder pot, 9: Raw material supply port

Claims

[Claim 1] A jet mill that grinds grains, tea leaves, or dried foods that do not contain oil or sugar into powder by the collision of compressed air sprayed from a pair of nozzles, The pair of nozzles are arranged on the same axis within the casing that forms the grinding chamber. The compressed air supplied to the pair of nozzles is compressed air that has been compressed by a compressor and then cooled to at least room temperature by a cooling device. The pair of nozzles is provided with a supply port for supplying the grain or tea leaves. A jet mill characterized by pulverizing grains, tea leaves, or dried foods that do not contain oil or sugar, supplied from the supply port, by causing them to collide with a fluid formed by the injection of compressed air cooled to at least room temperature from a nozzle.

Images