JP6831993B2 - Method for producing pregelatinized starch powder - Google Patents

Description

The present invention relates to a method for producing pregelatinized starch powder, and particularly to an improvement in technology in mass production.

It is generally known that by pregelatinizing (amorphizing) starch contained in grains, different characteristics are exhibited compared to before pregelatinization. For example, it is known that pre-pregelatinized rice flour can be stored for a long period of time, but can be eaten deliciously simply by adding water or hot water without the need for steaming. When starch is used as an additive to a biodegradable resin such as PLA (polylactic acid resin), starch is pregelatinized by simultaneously adding a plasticizer such as water or glycerin and treating the starch at a high temperature. It is known that this can be combined with PLA and the like.

Conventional pregelatinized starch is usually produced by suspending raw material grains in water, gelatinizing them by heating (that is, cooking rice), and then removing water. However, with the method of removing water after cooking rice and pregelatinizing it, it was possible to produce starch powder that was pregelatinized to the extent that it could be used as food simply by adding water or hot water, but it was pregelatinized to a degree close to complete. It was impossible to produce starch powder. The reason is that a part of starch that has been almost completely pregelatinized by cooking rice recrystallizes due to "aging" that occurs in the process of drying (water removal).

Further, when pregelatinized rice flour is used, a technique has been proposed in which a thickener is blended as various additives to commercialize the product (Patent Document 1).

The present inventors put the raw material grain into a mortar-type crusher and crush the raw material grain under shearing conditions while heating it to a temperature of 80 ° C. or higher, particularly 100 to 200 ° C., thereby highly pregelatinized alpha. We have developed a technique for easily producing chemical starch powder without adding water (Patent Documents 2 and 3). According to the technique described in Patent Document 2, the pregelatinization can be performed to the same extent as the method of pregelatinizing by removing water after cooking rice. Further, according to the technique described in Patent Document 3, a standard that is not pregelatinized in differential scanning calorimetry of pregelatinized starch due to conditions such as a gap between two relatively moving members, a heating temperature, and a water content of raw material grains. an endothermic enthalpy associated to the melting of the sample △ H _max and then alpha = when the _{(1- △ H T / △ H} max) endothermic enthalpy at the melting temperature, such as the numerical values indicated by × 100 alpha is 80 or more △ with H _T, it is possible to obtain a very high extent pregelatinized starch flour. This starch powder can have extremely high usefulness not only for applications in the food field but also as an additive to a completely different field, for example, a biodegradable resin such as PLA.

Japanese Patent No. 4190180 Japanese Patent No. 4767128 Japanese Patent No. 55038885

Patent Documents 2 and 3 have focused on a technique for achieving pregelatinization, but mass production has become a new issue in this technique. Under the conditions of mass production, it has not been found that the crystallinity can be controlled in order to obtain pregelatinized starch powder suitable for the food field and additives for biodegradable resins.

For example, a technique of blending a thickener as in Patent Document 1 is also known, but rice flour bread is made from 100% rice flour bread by adjusting the viscosity by blending pregelatinized rice flour and crystalline rice flour. It becomes possible. However, the technology that can control the crystallinity of rice and control the physical properties of dough such as bread simply by crushing it, and can produce foods such as rice flour bread without blending as described above has been established. Absent. By controlling the crystallinity, there is a demand for a technology that enables bread making without blending crystalline and amorphous grain flour as in the conventional technology, and pregelatinized starch that can freely control the degree of pregelatinization. Mass production of flour is desired. Furthermore, if grains can be pregelatinized in advance when grains are used as feed for livestock, it means that livestock feed that can control the growth rate of livestock can be developed for the purpose of adjusting the shipping time of livestock. To do. This requires a technique for freely controlling the degree of pregelatinization (degree of pregelatinization) of grains, but it is difficult to control the degree of pregelatinization by conventional general methods.

Further, as described above, under the conditions assuming that industrial mass production is carried out by the techniques of Patent Documents 2 and 3, clear findings related to pregelatinization even in pregelatinized starch powder having a high degree of crystallinity. And there was no guideline. For example, under the condition of mass-producing pregelatinized starch powder such that the crushed grain is discharged from a heating shear crusher at a discharge rate of 1 kg / hour or more, and further at a discharge rate of 10 kg / hour or more, the altitude as obtained in Patent Document 2 can be obtained. The specific conditions for obtaining pregelatinized starch powder and the like and the causal relationship between the conditions and mass production were not clear.

The present invention has been made in view of the above circumstances, and is a mass production condition in which a large amount of crushed grain is discharged when raw material grains are put into a heating shear crusher and crushed to produce pregelatinized starch powder. In order to obtain pregelatinized starch powder suitable for the food field and additives for biodegradable resins, pregelatinization capable of controlling the degree of crystallization over a wide range from a region having a high degree of crystallization to a region having a low degree of crystallization. An object of the present invention is to provide a method for producing starch powder.

In order to solve the above problems, in the method for producing pregelatinized starch powder of the present invention, the raw material grains are put into a heating shear crusher and crushed, and the crushed grains are discharged from the heating shear crusher at a discharge rate of 1 kg / hour. This is a method for producing pregelatinized cereal powder to be discharged as described above.
Q value = [residence time of raw grain in heat shear crusher (sec)] x [maximum shear rate (1 / sec)]
It is characterized in that the raw material grain is crushed under the condition that the Q value represented by is 500 or more.

According to the present invention, when raw material grains are put into a heating shear crusher and crushed to produce pregelatinized starch powder, they are added to the food field and biodegradable resins under mass production conditions in which the amount of crushed grains discharged is large. In order to obtain pregelatinized starch powder suitable for agents and the like, the degree of crystallization can be controlled in a wide range from a region having a high degree of crystallization to a region having a low degree of crystallization.

It is the schematic (top view, bottom view) which shows an example of the apparatus configuration for carrying out the method of this invention. It is sectional drawing of the main part of the apparatus of FIG. 3 is a wide-angle X-ray diffraction graph of rice flour obtained by milling in Reference Example 1 and uncrushed rice grains. 6 is a wide-angle X-ray diffraction graph of rice flour obtained by pulverizing rice flour at a discharge rate of 1 kg / hour or less in Reference Example 2. It is a graph which shows the relationship between the Q value and the crystallinity.

The present invention will be described in detail below.

The present invention is a method for producing pregelatinized starch powder, in which raw material grains are put into a heat shear crusher and crushed, and the crushed grains are discharged from a heat shear crusher at a discharge rate of 1 kg / hour or more. The amount of grain discharged from the heat shear crusher is 1 kg / hour or more, 3 kg / hour or more, 5 kg / hour or more, or 10 kg / hour or more.

As a result of repeated experiments and researches in view of the above problems, the present inventors have found that the gap between two relatively moving members of the crusher (such as a mortar crusher and a twin-screw kneading crusher) is the smallest. When the shear rate of is defined as the maximum shear rate and the product of it and the residence time (corresponding to the discharge amount) is defined as the Q value, surprisingly, the relative relationship with the degree of crystallization (corresponding to the degree of pregelatinization) is shown in the figure. We have found that the relationship is as clear as in 5, and have completed the present invention.

The fact that the degree of crystallinity can be controlled by the Q value means that it is very important to reduce the slight crystallinity by the Q value in terms of using pregelatinized rice flour and crystalline rice flour in combination for various purposes. For example, it is known that rice flour bread can be made into 100% rice flour bread by blending pregelatinized rice flour and crystalline rice flour. However, according to the present invention, since the crystallinity of rice can be controlled by the Q value, the physical properties of dough such as bread can be controlled only by crushing, and the production has been performed so far without blending as described above. Gluten-free foods, which have been difficult, can be easily produced.

As a result of using small to medium mortars, it was found that Q value = maximum shear rate x residence time (discharge amount) is an important factor that uniquely influences the crystallinity. In order to reduce the crystallinity, it is essential to increase the Q value. Since the residence time becomes shorter when the production amount (discharge amount) is increased, it is necessary to increase the maximum shear rate in order to increase the production amount while maintaining the crystallinity below a certain value.

Since the shear rate can be calculated by the peripheral speed / gap, it is important to increase the peripheral speed or decrease the gap by increasing the size of the mortar.

This relationship is not limited to the mortar-type crushing shape, and it can be easily inferred that it corresponds to other crushing manufacturing methods such as a twin-screw kneading crusher. That is, as the heating shear crusher, in addition to the mortar crusher as shown in FIGS. 1 and 2, any other device may be used as long as the method of the present invention can be carried out. In the present invention, "crushing under shear conditions" does not mean simply compressing and crushing, but crushing with an action of shifting both side portions along a surface inside the object. .. For example, as a device for applying a shearing force to a raw material grain to grind it, in addition to a mortar type crusher, a device for shearing and crushing while passing the raw material grain through a minute gap between two relatively rotating rollers. The composition and the small-diameter cylindrical or cylindrical member and the large-diameter cylindrical member are concentrically arranged and rotated relative to each other, and the raw material grain is passed through a minute gap between the outside of the small-diameter member and the inside of the large-diameter member. It is possible to adopt an apparatus configuration such as shear crushing during the process.

In the method of the present invention, the raw material grain is crushed under the condition that the Q value is 500 or more. When the Q value is 500 or more, it is possible to obtain pregelatinized starch flour in which the degree of crystallization of grains after crushing by a heating shear crusher is reduced to, for example, about 15, and crystalline rice flour or thickening polysaccharide can be obtained. It is possible to process and commercialize gluten-free foods without mixing sugars. In addition, starch powder that has been pregelatinized to a degree that can be used as food simply by adding water or hot water, and starch powder that has been pregelatinized to a very high degree as described in Patent Document 2 can also be obtained. It is possible to obtain pregelatinized starch powder in which the degree of pregelatinization is variously controlled within a range of low crystallinity.

Considering the point of obtaining pregelatinized starch powder having a low crystallinity, it is preferable to crush the raw material grain under the condition that the Q value is 3500 or more, and the raw material grain can be crushed under the condition that the Q value is 9000 or more. Especially preferable. Under such conditions, pregelatinized starch flour having a lower crystallinity can be obtained, and pregelatinized starch flour having a grain crystallinity of less than 6% after crushing by a heat shear crusher can be obtained, for example. You can also do it.

Under the condition that the discharge rate of the grain from the heat shear crusher is 1 kg / hour or more, it is preferable to crush the raw grain under the condition that the Q value is 300,000 or less, and the raw grain is crushed under the condition of 100,000 or less. Is more preferable. If the shear rate is increased under such a large amount of grain discharge, clogging is likely to occur.

When producing pregelatinized starch powder using a mortar crusher as a heat shear crusher, the gap between the upper mortar and the lower mortar is appropriately adjusted. The gap is not particularly limited in consideration of the grain used as a raw material and the size of the desired flour to be obtained after the treatment, but is, for example, in the range of 0.5 to 0.01 mm, particularly 0.1 to 0.01 mm. It is adjusted arbitrarily within. Next, after the mortar is brought to a predetermined temperature, the mortar is rotated at a predetermined rotation speed (corresponding to the shear rate of the grain). Then, the raw material grain is put into a mortar type crusher, and the raw material grain is crushed at a predetermined temperature under shearing conditions. Considering that it is possible to obtain pregelatinized starch powder in which the degree of pregelatinization is variously controlled in a range of low crystallinity, that is, that minute crystallinity control can also be controlled by a Q value, the temperature at the time of pulverization Is not particularly limited, but is pulverized under shearing conditions while being heated to, for example, room temperature or higher, or 40 ° C. or higher, preferably 80 ° C. or higher. The upper limit of the temperature at the time of pulverization is not particularly limited, but is preferably 200 ° C. or lower. The water content of the raw material grain is not particularly limited, but is preferably 10% or more.

In the present invention, the pregelatinized starch flour is intended for all cereals containing starch as a main component, such as rice, wheat, soybeans, adzuki beans, buckwheat, potatoes, legumes, and corn. These can be pregelatinized and milled in a short time.

The highly pregelatinized starch powder is expected to be used not only in the conventional food field but also in various fields. For example, since it exhibits good dispersibility and compatibility with plastics such as PLA, it not only eliminates the need to use plasticizers such as water and glycerin, but also has the effect of improving mechanical properties. Therefore, it is also useful as a plastic additive. Furthermore, it is an effective method as a pretreatment technique during bioethanol production, and it is possible to impart high enzymatic reactivity without going through the gelatinization (pregelatinization) step of the raw material starch as in the past, and gelatinization in bioethanol production. Since the (pregelatinization) process can be saved, the production process can be expected to be simplified.

Further, according to the present invention, by arbitrarily selecting the crushing conditions, pregelatinized starch powder having various degrees of pregelatinization can be produced, so that grains having different swelling properties with respect to cold water can be produced. That is, grain flour having various dough viscosities can be arbitrarily produced. This can also be obtained by the present invention for breads such as 100% rice flour bread, which have conventionally been considered to be practically impossible to make bread due to the lack of stickiness of the dough, and "connectors" in 100% buckwheat noodles. It becomes possible to apply pregelatinized starch powder as a viscosity modifier.

Furthermore, according to the present invention, since starch can be easily and instantly pregelatinized, it is possible to eliminate the need for all processing processes that required a pre-step of boiling, and it has an extremely wide range of applications. .. For example, as an industrial material, saccharification of starch in synthesizing lactic acid, which is a raw material of a biodegradable resin, plastic / starch composite material, pregelatinization obtained by the method of the present invention in a bioethanol production process, etc. If starch powder is used, the pre-step is not required, and the pregelatinization step such as rice cooking, which is required by the prior art, can be omitted, which is a great advantage in terms of cost and process. In addition, in the case of fermentation in the sake brewing process, koji fermentation in the production of miso, etc., the pre-process of boiling grains such as corn, rice, and wheat flour, which are mainly made of starch, has always been required (rice cooking). However, if the pregelatinized starch obtained by the present invention is used, the pre-step is unnecessary, and similarly, there is a great advantage in terms of cost and process.

As described above, the pregelatinized starch powder obtained by the method of the present invention is expected to be widely applicable not only as a food product but also as an industrial material, and the present invention is remarkably high in a wide range of industrial fields. Has availability.

FIG. 1 is a schematic view showing an example of an apparatus configuration for carrying out the method of the present invention. The device 10 has a fixedly installed upper mortar 11 and a lower mortar 12 rotatably provided between the upper mortar 11 via a predetermined gap 13. The upper mortar 11 has a raw material input port 14 for inputting raw material grains such as rice grains in the center, and is formed in a ring shape. The insertion port 14 leads to the gap 13 on the bottom surface of the upper mill 11. The lower mortar 12 is formed in a disk shape having substantially the same outer diameter as the upper mortar 11.

The lower mill 12 is rotationally driven by the motor 15 at a predetermined speed. The gap 13 between the upper mill 11 and the lower mill 12 can be adjusted within the range of the gap adjusting portion 16, and is particularly dependent on the grain used as the raw material and the desired size of the flour to be obtained after the treatment. Although not limited, it is arbitrarily adjusted within the range of, for example, 0.5 to 0.01 mm, particularly about 0.1 to 0.01 mm.

A heater 17 is provided on the upper mill 11. The heater 17 has a ring shape having substantially the same outer diameter as the upper mill 11 and having an opening having substantially the same diameter as the raw material input port 14. The heater 17 is connected to the temperature controller 19 via the heater cord 18, and is heated to the temperature set by the temperature controller 19 to heat the upper mill 11 on the entire surface. The computer 22 compares the set temperature (input from the data cable 23) by the temperature controller 19 with the measured temperature (input from the data cable 21) by the thermocouple (not shown), and heats the heater via the temperature control cable 24. A control signal is given to the temperature controller 19.

Further, the computer 22 gives a motor control signal to the motor 15 via the motor control cable 25 to control the rotation speed of the lower mill 12 by the motor 15. The number of rotations of the lower mortar 11 is set so that the shear rate received by the grains thrown into the gap 13 between the fixed upper mortar 11 and the rotating lower mortar 12 becomes a target value.

Below the upper mortar 11 / lower mortar 12, a saucer 26 having an inner diameter sufficiently larger than these outer diameters is provided. A flour drop port 27 is opened on the bottom surface of the saucer 26, and the flour (rice flour, etc.) processed by this device 10 is dropped from the saucer 26, and further passed through a flour drop chute 28 to a predetermined container (not shown). I try to accommodate it in such places.

As shown in FIG. 2, which is a cross-sectional view of a main part of the device 10, in the upper mill 11, the raw material passage 11c from the inner surface 11a facing the raw material input port 14 to the bottom surface 11b is tapered in cross-sectional view and spiral in plan view. It is formed in a shape. Since the accommodating portion 20 enlarged by the tapered passage 11c is formed at the lower end of the raw material input port 14, the raw material grain input into the raw material input port 14 enters the gap 13 and is immediately before being sheared and crushed. It enters the accommodating portion 20 and is heated by heat transfer or heat dissipation from the inner surface 11a of the upper mill 11 heated by the heater 17. The thermocouple described above approximately indicates the processing temperature when the thermocouple is inserted into a hole formed from the side surface of the upper mill 11 toward the center and is sheared and crushed in the gap 13 between the upper mill 11 and the lower mill 12. ing. On the surface of the upper mortar 11 and the lower mortar 12 facing the gap 13, a large number of concave grooves extending in the direction intersecting the circumferential direction are formed in order to increase the shearing force on the raw material grain.

Next, the pregelatinized milling treatment performed using this apparatus 10 will be described. First, the gap 13 between the upper mill 11 and the lower mill 12 is adjusted via the gap adjusting portion 16 according to the size of the raw material grains and the processed flour. Further, the temperature controller 19 heats the heater 17 to a predetermined temperature (for example, it can be set in increments of 10 ° C. within the range of 80 to 140 ° C.), and the upper mill 11 is heated by the heat conduction. Further, the motor 15 is driven at a rotation speed controlled by the computer 22 to rotate the lower mill 12 so as to give the predetermined shear rate.

Now that the preparation of the apparatus 10 is completed, the raw material grains are put into the inlet 14 and the process is started. Since the heater 17 has already been heated to a predetermined temperature, and the upper mill 11 is also heated by this, the grains pass through the heater 17 and the input port 14, and further pass through the tapered passage 11c to the accommodating portion 29. It is heated to a temperature corresponding to the heater temperature, and immediately after that, it is sent into the gap 13 between the lower mill 12 and receives a shearing force between the fixed upper mill 11 and the rotating lower mill 12 to be crushed. Will be done. The flour (rice flour) obtained by shearing is discharged from the side of the gap 13 and stored in the saucer 26, and is collected in a predetermined container (not shown) via the drop port 27 and the drop chute 28.

Hereinafter, the present invention will be described in more detail with reference to Examples, but the present invention is not limited to these Examples.

In the following examples, the shear rate, residence time, Q value, and crystallinity of crushed rice flour were measured by the following methods.
(1) Maximum shear rate The peripheral speed was obtained from the rotation speed of the motor 15 and the circumferences of the upper and lower mortars 11 and 12, and the maximum shear rate crushed was defined from the value of the gap 13 from the following relationship.
Circumferential speed [mm / s] = (rotation speed [rpm] x circumference [mm]) / 60
Maximum shear rate [1 / sec] = peripheral speed [mm / s] / gap [mm])
(2) Dwelling time The dwelling time was defined from the following relationship from the value of the discharge amount at the time of crushing.
Dwelling time [sec] = 1 / Discharge amount (3) Q value The Q value was calculated from the following formula.
Q value = [residence time of raw grain in heat shear crusher (sec)] x [maximum shear rate (1 / sec)]
(4) Crystallinity The peaks were separated into crystal reflection and amorphous scattering from the measurement results of wide-angle X-ray diffraction. The integral value of the peak due to the resulting amorphous scattering S _a, the integral value of the peak due to the crystal reflecting the S _c. The crystallinity of the crushed rice flour was determined from the following relationship.
Crystallinity (%) = (S _c / (S _c + S _a )) × 100
The experimental specifications of the wide-angle X-ray diffraction are as follows.
・ Measuring equipment RINT-RAPID manufactured by Rigaku
・ Measurement conditions Scan speed 4 ° / min
Measuring angle 5 to 35 °
Tube voltage 40kV
Tube current 30mA
<Reference example 1>
Raw rice was roughly pulverized in a mortar and subjected to wide-angle X-ray diffraction.
<Reference example 2>
Using rice grains having a water content of 14.4%, which is standard for general stored rice, as a raw material, milling was actually performed using the apparatus 10 having the configuration shown in FIGS. 1 and 2. In the device 10 used, the upper mortar 11, the lower mortar 12, and the heater 17 all have an outer diameter of 90 mm (radius 45 mm), and have an input port 14 having a diameter of 10 mm at the center thereof. The tapered raw material passage 11c of the upper mill 11 is formed over a range of 5 mm from the inner surface 11a (FIG. 2). The gap 13 between the mortars was fixed at 0.01 mm (10 μm), the rotation speed of the motor 15 was 240 rpm, and the amount of rice grains charged was 120 g / h, and the actual milling process was performed. Further, the milling process was performed at a crushing temperature of 120 ° C.
<Reference example 3>
The device 10 having the same configuration as that of Reference Example 2 was used, but in this example, the external dimensions of the lower mortar 12 were changed to 60 mm (radius 30 mm), the gap 13 between the mortars was fixed to 0.01 mm (10 μm), and the motor was used. The rotation speed of 15 was 100 rpm, and the amount of rice grains added was 120 g / h for the actual milling process. Further, the milling process was performed at a crushing temperature of 120 ° C.
<Reference example 4>
Using the device 10 having the same configuration as that of Reference Example 2, the gap 13 between the mortars is fixed to 0.01 mm (10 μm), the rotation speed of the motor 15 is 240 rpm, and the amount of rice grains input is 200 g / h. Milling was performed. Further, the milling process was performed at a crushing temperature of 120 ° C.
<Reference example 5>
The device 10 having the same configuration as that of Reference Example 2 was used, but in this example, the external dimensions of the lower mortar 12 were changed to 60 mm (radius 30 mm), the gap 13 between the mortars was fixed to 0.01 mm (10 μm), and the motor was used. The rotation speed of 15 was set to 240 rpm, and the actual milling process was performed at an input amount of rice grains of 200 g / h. Further, the milling process was performed at a crushing temperature of 120 ° C.

<Example 1>
The device 10 having the same configuration as that of Reference Example 2 was used, but in this embodiment, the upper mortar 11, the lower mortar 12, and the heater 17 are all formed with an outer diameter of 250 mm (radius 125 mm). The gap 13 between the mortars was fixed at 0.01 mm (10 μm), the rotation speed of the motor 15 was set to 50 rpm, and the amount of rice grains charged was 6.5 kg / h, and the actual milling process was performed. Further, the milling process was performed at a crushing temperature of 120 ° C.
<Example 2>
Using the device having the same configuration as in Example 1, the gap 13 between the mortars was fixed to 0.01 mm (10 μm), the rotation speed of the motor 15 was 100 rpm, and the input amount of rice grains was 6.5 kg / h. The actual milling process was performed. Further, the milling process was performed at a crushing temperature of 120 ° C.
<Example 3>
Using the device having the same configuration as in Example 1, the gap 13 between the mortars was fixed to 0.01 mm (10 μm), the rotation speed of the motor 15 was 50 rpm, and the input amount of rice grains was 11.5 kg / h. The actual milling process was performed. Further, the milling process was performed at a crushing temperature of 120 ° C.
<Example 4>
Using the device having the same configuration as that of the first embodiment, the gap 13 between the mortars was fixed to 0.01 mm (10 μm), the rotation speed of the motor 15 was 100 rpm, and the input amount of rice grains was 11.5 kg / h. The actual milling process was performed. Further, the milling process was performed at a crushing temperature of 120 ° C.
<Example 5>
Using the device having the same configuration as in Example 1, the gap 13 between the mortars was fixed to 0.04 mm (40 μm), the rotation speed of the motor 15 was 45 rpm, and the amount of rice grains charged was 6.5 kg / h. The actual milling process was performed. Further, the milling process was performed at a crushing temperature of 120 ° C.
<Example 6>
Using the device having the same configuration as in Example 1, the gap 13 between the mortars was fixed to 0.07 mm (70 μm), the rotation speed of the motor 15 was 45 rpm, and the amount of rice grains charged was 4 kg / h. Milling was performed. Further, the milling process was performed at a crushing temperature of 120 ° C.
<Example 7>
Using the device having the same configuration as in Example 1, the gap 13 between the mortars was fixed to 0.1 mm (100 μm), the rotation speed of the motor 15 was 45 rpm, and the input amount of rice grains was 6.5 kg / h. The actual milling process was performed. Further, the milling process was performed at a crushing temperature of 120 ° C.
<Example 8>
Using the device having the same configuration as in Example 1, the gap 13 between the mortars was fixed to 0.3 mm (300 μm), the rotation speed of the motor 15 was 45 rpm, and the input amount of rice grains was 6.5 kg / h. The actual milling process was performed. Further, the milling process was performed at a crushing temperature of 120 ° C.
<Example 9>
Using the device having the same configuration as in Example 1, the gap 13 between the mortars was fixed to 0.5 mm (500 μm), the rotation speed of the motor 15 was 45 rpm, and the input amount of rice grains was 6.5 kg / h. The actual milling process was performed. Further, the milling process was performed at a crushing temperature of 120 ° C.
<Example 10>
Using the device having the same configuration as in Example 1, the gap 13 between the mortars was fixed to 0.7 mm (700 μm), the rotation speed of the motor 15 was 45 rpm, and the input amount of rice grains was 6.5 kg / h. The actual milling process was performed. Further, the milling process was performed at a crushing temperature of 120 ° C.

<Comparative example 1>
Using the device having the same configuration as in Example 5, the gap 13 between the mortars was fixed to 1 mm (1000, incense j), the rotation speed of the motor 15 was 45 rpm, and the amount of rice grains charged was 6.5 kg / h. The actual milling process was performed. The milling process was performed at a crushing temperature of 120.
<Comparative example 2>
Table 4 shows the crystallinity of uncrushed rice grains having a Q value of zero.

As described above, the crystallinity at each Q value was measured by changing the input amount, the mortar diameter, the rotation speed, the shear rate, the discharge amount, the residence time, and the like. The results are shown in Tables 1 to 4. Moreover, these results are shown in FIG. 5 as a graph of Q value and crystallinity.

From Tables 1 to 4, the product of the maximum shear rate and the residence time was defined as the Q value under the condition that the crushed rice powder was discharged from the mortar crusher at a discharge rate of 1 kg / hour or more. It was found that the relative relationship with and is a clear relationship as shown in FIG. In other words, we found that the Q value is an important factor that uniquely affects the crystallinity, and in order to reduce the crystallinity, it is essential to increase the Q value, and the production amount (discharge amount). Since the residence time becomes shorter when the amount is increased, it is clarified that it is necessary to increase the maximum shear rate in order to increase the production amount while maintaining the crystallinity below a certain value.

10 Heating shear crusher 11 Upper mortar 11a Inner surface 11b Bottom surface 11c Tapered raw material passage 12 Lower mortar 13 Gap 14 Raw material input port 15 Motor 16 Gap adjustment unit 17 Heater 18 Heater code 19 Temperature controller 20 Storage unit 21 Data cable 22 Computer 23 Data Cable 24 Temperature control cable 25 Motor control cable 26 Usu 27 Grain drop port 28 Grain drop chute

Claims (7)

A method for producing pregelatinized starch powder in which raw material grains are put into a heat shear crusher and crushed, and the crushed grains are discharged from a heat shear crusher at a discharge rate of 1 kg / hour or more.
Q value = [residence time of raw grain in heat shear crusher (sec)] x [maximum shear rate (1 / sec)]
The raw material grain is crushed under the condition that the Q value represented by is 500 or more.
A method for producing pregelatinized starch powder, wherein the crystallinity of the pregelatinized starch powder is controlled by controlling the Q value. The method for producing pregelatinized starch powder according to claim 1, wherein the heat shear crusher is a mortar crusher. The method for producing pregelatinized starch powder according to claim 1 or 2, wherein the raw material grain is crushed under the condition that the Q value is 9000 or more. The method for producing pregelatinized starch powder according to any one of claims 1 to 3, wherein the amount of grains discharged from the heat shear crusher is 10 kg / hour or more. The method for producing pregelatinized starch powder according to any one of claims 1 to 4, wherein the raw material grain is heated to a temperature of 80 ° C. or higher and pulverized. The method for producing pregelatinized starch powder according to any one of claims 1 to 5, wherein the water content of the raw material grain is 10% or more. The method for producing pregelatinized starch powder according to any one of claims 1 to 6, wherein the crystallinity of the grain after crushing by a heat shear crusher is less than 6%.