JP7365605B2 - Method for producing pregelatinized starch powder - Google Patents

Description

Application of Article 30, Paragraph 2 of the Patent Act Published on August 29, 2018 in Proceedings of the Society of Polymer Science, Vol. 67, No. 2 (2018), presentation number 1Pe073

The present invention relates to a method for producing pregelatinized starch powder.

It is generally known that by pregelatinizing (amorphizing) the starch contained in grains, different properties are developed compared to those before pregelatinization. For example, it is known that pre-gelatinized rice flour can be stored for a long time and can be deliciously eaten simply by adding water or hot water without requiring steaming. In addition, when starch is used as an additive to biodegradable resins such as PLA (polylactic acid resin), the starch is pregelatinized by adding water and a plasticizer such as glycerin at the same time and treating it at high temperature. It is known that this allows it to be combined with PLA and the like.

The present inventors introduced raw material grain into a mortar-type mill and crushed it under shearing conditions while heating the raw material grain to a temperature of 80°C or higher, particularly 100 to 200°C, thereby achieving highly pregelatinized grains. We have developed a technology to easily produce pregelatinized starch powder without adding water (Patent Documents 1 to 3). Application to technology for manufacturing high-quality shaped rice flour bread using rice flour dough that expands well through yeast fermentation and has sufficient moldability and shape retention (Patent Document 4), and various other technical fields including the food field. It is expected that the technology will become widespread, and it is also being put into practical use.

The conventional apparatus for producing the pregelatinized starch powder developed by the present inventors uses an upper mill and a lower mill, and inserts the input port into the central part into a planar gap formed between them. Raw material grains are introduced, transferred from the center to the outer periphery, heated while being retained, and pulverized by applying shear force through the relative rotation of the upper and lower mills, and expelling pregelatinized starch powder from the outer periphery. ing. In this case, the axis of rotation of the relatively rotating grinding section and the flow of material are perpendicular.

In the above-mentioned conventional technology, the main focus was on technology to achieve alpha conversion, but as a further step, a technology suitable for mass production, especially high discharge, was desired.

In view of this situation, in Patent Document 5, Q=[residence time of raw grain in heated shear crusher (sec)]×[maximum shear rate (1/sec)]
We propose a method for producing pregelatinized starch powder by pulverizing raw material grains by showing the conditions for the Q value expressed by .

Patent No. 4767128 Patent No. 5503885 Japanese Patent Application Publication No. 2009-213472 Patent No. 5769053 JP2018-38368A

In Patent Document 5, there is an example in which the rotation axis of the relatively rotating crushing section and the flow of material are perpendicular to each other. Patent Document 5 describes that the method of Patent Document 5 can be applied by analogy when the rotation axis of the relatively rotating crushing section and the material flow are parallel, but the rotation axis of the relatively rotating crushing section When we attempted pulverization using the kneader section of a twin-screw extruder, which is a typical mechanism in which the flow of materials is parallel to each other, we found that specifying the range using the Q value described above did not yield a good pulverized product.

To summarize the above, within the conventional parameter range, there is a problem that the conventional technology cannot cope with the case where the rotation axis of the crushing section and the material flow are parallel, as typified by a twin-screw extruder.

The present invention was made in view of the above-mentioned circumstances, and uses a heated shear pulverizer, typically a twin-screw extruder, which has a structure in which the rotating axis of the pulverizer mechanism and the flow of raw material grain are parallel to each other. It is an object of the present invention to provide a method for producing pregelatinized starch powder that can yield a good pulverized product in cases where the powder is pregelatinized.

In order to solve the above-mentioned problems, the present inventor conducted intensive studies and found that a heated shear crusher, typically a twin-screw extruder, has a structure in which the rotating axis of the crushing mechanism and the flow of the raw grain are parallel to each other. In some cases, the inventors have discovered that a good pulverized product can be obtained by using the Q _E value defined below instead of the Q value of Patent Document 5, and have completed the present invention.

That is, the method for producing pregelatinized starch powder of the present invention is a method for producing pregelatinized starch powder using a heated shear mill having a structure in which the rotation axis of the milling mechanism and the flow of raw material grain are parallel to each other, and includes the following steps. formula:

で与えられるQ_E値を400以上とすることを特徴としている。

It is characterized by having a _QE value of 400 or more.

According to the present invention, it is possible to produce good pregelatinized rice flour by heating and shearing and crushing using a twin-screw extruder, which is expected to be extremely effective in mass production.

A schematic diagram showing an example of the main parts of a component device for carrying out the method of the present invention (the upper part is a top view and the lower part is a side view) An example of the configuration device described in Patent Document 5, which is a reference example (the top is a top view and the bottom is a side view) Results of X-ray diffraction experiments on low-crystalline rice flour produced using this method Relationship between crystallinity and _QE value (Example) Relationship between crystallinity and Q value (comparative example) Results of X-ray diffraction experiments on low-crystalline rice flour obtained using conventional methods

The present invention will be explained in detail below.

The maximum shear rate is indicated by the following symbol:

で表されるが、出願書類作成の都合上、以下の記述においては便宜的にγ[・]と記載する場合がある。

However, for convenience in preparing application documents, it may be written as γ[・] in the following description for convenience.

The method for producing pregelatinized starch powder of the present invention is a method for producing pregelatinized starch powder using a heated shear mill having a structure in which the rotating shaft of the milling mechanism and the flow of raw material grain are parallel to each other.

Note that in this specification, the flow of raw material grains is not a local flow but an overall average flow. Therefore, even if the local flow is not parallel to the rotational axis of the crushing mechanism because it follows a spiral due to the screw of the crushing mechanism, the present invention applies if the overall average flow is parallel to the rotational axis of the crushing mechanism. included.

Furthermore, in this specification, the term "parallel between the rotation axis of the crushing mechanism and the flow of the raw material grains" means that the angle formed between the rotation axis of the crushing mechanism and the flow of the raw material grains (the above-mentioned overall average flow) is within 40 degrees. In particular, it is preferably within 30°.

In the present invention, the heating shear pulverizer is not particularly limited, but includes an extrusion-type pulverizer that includes a heating device and a pulverizer, has a screw-type extrusion mechanism, and pulverizes and discharges at the same time as heating while feeding. Other examples include mills equipped with a conical cutter equipped with a temperature control device, mills equipped with an inner cylindrical member and an outer cylindrical member, and the like. Here, the crusher equipped with an inner cylindrical member and an outer cylindrical member includes a cylindrical member that extends vertically, and a cylindrical member that extends vertically and is inserted into this cylindrical member. An input port for raw grain is formed between the member and the cylindrical member. A gap is formed between the inner circumferential surface of the cylindrical member and the outer circumferential surface of the cylindrical member, and a gap is formed that continues vertically from the input port. It has a structure in which an outlet for pregelatinized starch powder produced by crushing and pregelatinizing raw material grains in the gap is formed continuously from the gap. Then, the raw grain is introduced into the gap between the relatively rotating mortar-type structures, and the raw grain is crushed and pregelatinized by applying shearing force while heating.

A typical example of such a heating shear crusher is a twin-screw extruder. Other examples include, for example, a uniaxial continuous solid phase shear kneader.

The structure of the kneading section in a heated shear crusher is as shown in Fig. 1, in which a plurality of kneading units with kneading teeth on the outer periphery are provided in the direction of the rotation axis, and a Examples include a structure for shearing raw grain, and a single-shaft kneader equipped with a special millstone-shaped blade. However, the structure of the kneading part of the present invention is not limited to this, and any structure that can be pulverized by shearing may be used.

In this specification, at least the grain that is fed into the cylinder section and passes through the kneading section is referred to as "raw material grain." The grain flour discharged from at least the heated shear mill through the cylinder section according to the method of the invention is referred to as "gelatinized starch flour".

The gap in the kneading part of the heated shear crusher is not particularly limited, taking into account the grains used as raw materials and the desired size of flour to be obtained after processing, but for example, it is about 0.4 to 0.1 mm, especially about 0.2 mm. Adjusted within the following range.

FIG. 1 shows an example of a crushing mechanism for implementing the present invention. This pulverization mechanism uses a twin-screw extruder as a heated shear pulverizer, and is equipped with a mechanism for adjusting the temperature of the entire or part of the pulverization mechanism. The raw material grains flow in the direction of arrow 7 in Figure 1 from the input port side to the discharge port side. 1 is a cylinder part, and a first screw 2 and a second screw 3 are installed so that their rotation centers 4 and 5 are parallel to each other. The first screw 2 has an input side full flight section 2a, a kneading section (from a starting point 2b to an end point 2c), and a discharge port side full flight section 2d installed from the upstream side to the downstream side. From the upstream side to the downstream side, an inlet side full flight section 3a, a kneading section (from a start point 3b to an end point 3c), and an outlet side full flight section 3d are installed. The kneading section has a plurality of kneading units equipped with kneading teeth on the outer periphery in the direction of the rotation axis, and forms a clearance 6 with the inner circumferential surface of the cylinder section 1 to shear the raw grain. It looks like this.

Here, we will consider some factors related to alpha conversion. One of them is the maximum shear rate γ[・](1/sec). Work is applied to the material by shear strain. The total amount of work that the material undergoes in the mill can be evaluated as the total shear strain. The total amount of shear strain is related to the following Q, which is defined as the product of residence time τ (sec) of the raw grain in the heated shear crusher.

特許文献５では、アルファ化の指標となる結晶化度がQの減少関数になることが議論されている。結晶化度が低いほど非晶質化（アルファ化）の程度が高くアルファ化米粉の品質が良好であることから、特許文献５では、特定のQ以上の条件で粉砕することを見出していた。本発明は図１に代表される粉砕機構によりヒーターによる加熱と同時にせん断を加えることで原料穀物を粉砕し非晶質化させるものであるが、特許文献５のQ値を図１の粉砕機構に適用することができないことが分かった。

Patent Document 5 discusses that crystallinity, which is an index of alphaning, becomes a decreasing function of Q. Since the lower the degree of crystallinity, the higher the degree of amorphization (gelatization) and the better the quality of the gelatinized rice flour, Patent Document 5 found that it is ground under conditions of a specific Q or higher. The present invention uses a crushing mechanism represented by FIG. 1 to crush and amorphize raw material grains by applying shear at the same time as heating with a heater. It turned out that it could not be applied.

As a result of investigation, it was found that the cause was the difference between the crushing mechanism in FIG. 1 and the crushing mechanism in FIG. 2 (reference example corresponding to Patent Document 5). One reason is that in FIG. 2 (reference example corresponding to Patent Document 5), pulverization is performed between the gaps of several microns between the upper and lower flat plate dies, whereas in FIG. This is done at the kneading section between 2b and 2c and between 3b and 3c. The second cause is the direction of flow of raw material grain. In the mechanism shown in FIG. 2, a gap 14 is formed between the upper mill 8 and the lower mill 9, raw grain is inputted from the input port 10 of the upper mill 8, and the lower mill rotates around the rotation center 11. The material is pulverized while being fed in a direction perpendicular to the axis of rotation represented by 12 and 13.

On the other hand, in the case of FIG. 1, the material is pulverized while being fed in the direction of arrow 7, which is parallel to the rotation axis of the screw shaft. As a result of considering these differences, it has been found that the filling rate φ of the material in the kneading part, which is a factor that was not considered in the Q value of equation (1), is important. As a result of the study, it was found that when the rotation axis and the material flow are parallel, as shown in Figure 1, it is appropriate to use the _QE value defined below instead of the Q value in equation (1). Ta.

もちろん、式(1)のQ値を図１の構成装置に対して計算することも可能であるが、特許文献５で示された結果にならない場合があることが判明した。

Of course, it is also possible to calculate the Q value of equation (1) for the configuration device shown in FIG. 1, but it has been found that the results shown in Patent Document 5 may not be obtained in some cases.

In the method of the present invention, raw material grains are crushed under conditions such that the Q _E value of formula (2) is 400 or more, preferably 500 or more. If the _QE value is 400 or more, it is possible to obtain pregelatinized starch powder in which the crystallinity of the grain after milling with a heated shear mill has been lowered to about 15%, for example, and crystalline rice flour and It becomes possible to process and commercialize gluten-free foods without mixing mucopolysaccharides. It is also possible to obtain starch powder that has been pregelatinized to the extent that it can be used as food by simply adding water or hot water, as well as starch powder that has been pregelatinized to a very high degree. Various controlled pregelatinized starch powders can be obtained in a low range.

Considering the point of obtaining pregelatinized starch powder with a low degree of crystallinity, it is preferable to crush the raw material grain under conditions where the above Q _E value is 600 or more, and the raw material grain is crushed under conditions where the above Q _E value is 800 or more. It is particularly preferable. Under these conditions, it is possible to obtain pregelatinized starch powder with a lower degree of crystallinity, and obtain pregelatinized starch powder in which the crystallinity of the grain after milling with a heated shear mill is, for example, less than 5%. You can also do that.

Under conditions where the grain discharge rate from the heated shear crusher is 50 kg/hour or more, it is preferable to crush the raw material grain under conditions where the above _QE value is 10 ^{5 or} less; It is more preferable to crush it.

The raw grain is put into a heated shear crusher, and the raw grain is crushed under shear conditions at a predetermined temperature. Considering that it is possible to obtain pregelatinized starch powder with various degrees of pregelatinization controlled within a low crystallinity range, that is, precise crystallinity control can be controlled by the _QE value, Although the temperature is not particularly limited, it may be, for example, at room temperature or higher, or it may be pulverized under shearing conditions while being heated to 40°C or higher, preferably 80°C or higher. The upper limit of the temperature during pulverization is not particularly limited, but is preferably 200°C or lower. The moisture content of the raw material grain is not particularly limited, but is preferably 10% or more.

In the present invention, the pregelatinized starch powder is intended for all grains whose main ingredient is starch, such as rice, wheat, soybeans, adzuki beans, buckwheat, potatoes, beans, and corn. These can be pregelatinized and milled in a short time.

The conventional pregelatinization method involves adding water, pregelatinization by heating, and then drying and pulverizing. According to this method, it is known that when raw starch contains lipid molecules, the lipid molecules are complexed with amylose to form an amylose-lipid complex due to high temperature treatment during water addition. Since the pregelatinized starch produced in the present invention is produced by amorphization during heating without adding water, sufficient molecular movement for amylose to encapsulate lipid molecules does not occur. Therefore, it is possible to obtain a material in which amylose does not include lipid molecules even in the presence of lipid molecules. Specifically, the pregelatinized starch powder is obtained in which the ratio of the diffraction peak of the lipid complex around the diffraction angle of 20 degrees in the X-ray diffraction intensity is 0% or more and 1% or less, and further 0% or more and 0.7% or less. It will be done.
<Example>
EXAMPLES The present invention will be explained in more detail with reference to Examples below, but the present invention is not limited to these Examples.

The apparatus, experimental method, and parameters for realizing the present invention will be described below.
[1] The extruder used was a twin-screw extruder KZW-30 manufactured by Technovel Co., Ltd., which was constructed with two screws consisting of a full-flight part on the input side, a kneading part, and a full-flight part on the discharge side, as shown in Figure 1. A device was used. Five kneading units consisting of five 15 mm clockwise 45° kneading teeth were installed on the extruder outlet side, and the other parts were made into full-flight parts.
[2] Produced rice flour Rice flour was produced by crushing raw rice using the extruder described in [1] above. Based on Patent Documents 1 to 3, pulverization was performed simultaneously with heating. The temperature at the input port was 80°C, the temperature at the kneading part was 130°C, and the temperature at the part connecting the two was set at 100°C to create a temperature gradient. Rice was input through the input port and flowed through the extruder to be crushed to produce rice flour. The rotation speed N _r (rpm) and input amount M (g/sec) are summarized in Table 1 as parameters. The raw rice used was Haenuki rice grown in 2016.
[3] Crystallinity Based on the measurement results of wide-angle X-ray diffraction, the peak was separated into crystalline reflection and amorphous reflection. Let S _a be the integral value of the peak due to the obtained amorphous scattering, and S _c be the integral value of the peak due to crystal reflection. The crystallinity of the ground rice flour was determined from the following relational expression.

各条件で製造した米粉の結晶化度を表１にまとめた。

Table 1 summarizes the crystallinity of rice flour produced under each condition.

The experimental specifications for the wide-angle X-ray diffraction described above are as follows.
・Measuring equipment Ultima V manufactured by Rigaku
・Measurement conditions Scan speed 10°/min
Measuring angle 5~35°
X-ray source Cu-Kα ray Tube voltage 40kV
Tube current 40mA
FIG. 3 shows the diffraction angle dependence of the wide-angle X-ray diffraction intensity of rice flour obtained under Conditions 1 and 5 in Table 1, and as a reference example by coarse pulverization without using a heated shear pulverizer.
[4] Percentage occupied by amylose/lipid complex From the wide-angle X-ray diffraction intensity obtained with the above wide-angle As _S.L.

によって、アミロース／脂質複合体が占める割合を求めた。

The proportion occupied by the amylose/lipid complex was determined.

Regarding condition 1, condition 5, and condition 17 of Table 1, which shows the wide-angle X-ray diffraction results in FIG. 3, the proportions occupied by the amylose/lipid complex were 0.3%, 0.5%, and 0.3%, respectively. The results are shown in Table 2. The experimental specifications for the X-ray diffraction experiment were as described in [3] above.
[5] Maximum shear rate γ[・]
From the screw rotation speed N _r (rpm), the gap h shown by the symbol 6 in Fig. 1, and the cylinder diameter D in Fig. 1, the maximum shear rate γ [・] can be calculated as follows:

で求めた。ただし、πは円周率である。
[6] 滞留時間τ
滞留時間は、ニーディング部を通り過ぎる原料穀物の速さとして、

I asked for it. However, π is pi.
[6] Residence time τ
Residence time is defined as the speed of raw grain passing through the kneading section.

によって求める。ただし、Lはニーディング部の長さであり、P_nはニーディング部におけるスクリュウの螺旋構造の一巻きの回転軸方向の長さである。P_nN_rは１分あたりにニーデ
ィングの螺旋構造が送り出す原料穀物の回転軸方向の最大進行距離を表す。ニーディング部に螺旋構造がない装置の場合には、その装置の送り出し機構に応じてニーディング部で
の滞留時間を計算すればよい。
[7] 充填率φ
理論的な充填率φ^*は、シリンダー中空部の単位長さあたりの体積v_c(cm²)と、第一および第二スクリュウを合わせたニーダー部の単位長さあたりの体積v_n(cm²)、また、材料の
投入量M(g/min)、材料の密度ρ(g/cm³)によって、

Find it by However, L is the length of the kneading part, and P _n is the length of one turn of the helical structure of the screw in the direction of the rotation axis in the kneading part. P _n N _r represents the maximum traveling distance of the raw material grain in the direction of the rotation axis per minute by the spiral structure of the kneading. In the case of an apparatus without a helical structure in the kneading part, the residence time in the kneading part may be calculated according to the delivery mechanism of the apparatus.
[7] Filling rate φ
The theoretical filling rate φ ^* is the volume per unit length of the cylinder hollow part v _c (cm ² ) and the volume per unit length of the kneader part including the first and second screws v _n (cm ² ), and depending on the material input amount M (g/min) and the material density ρ (g/cm ³ ),

is given by For example, when the cross section of the cylinder hollow part has the shape of two overlapping circles as shown in Figure 1, v _c (cm ² ) is calculated by the following formula given by the cylinder diameter D and the distance between cylinders E.

によって求められるが、シリンダー部の形状によっては断面形状の測定などによって求められる。v_nはニーダー部分のサイズを測定することで求められる。本発明では、澱粉粉体の密度ρは材料によらずほぼ一定と仮定し、充填率φとして、

However, depending on the shape of the cylinder part, it can be determined by measuring the cross-sectional shape. v _n is determined by measuring the size of the kneader part. In the present invention, it is assumed that the density ρ of starch powder is almost constant regardless of the material, and the filling rate φ is

を用いることとした。
[8] ニーディングの歯の数 n
nは、ニーディングの歯の数であるが、同じ角度で連続して配置された歯の数は1つとして計算することとした。
[9] Q_E値
式(2)、(3)、(4)、(7)より得られる式(8)で与えられるQ_Eを用いる。

We decided to use
[8] Number of kneading teeth n
n is the number of kneading teeth, but the number of teeth consecutively arranged at the same angle was calculated as one.
[9] Q _E value Use Q _E given by equation (8) obtained from equations (2), (3), (4), and (7).

表１にn, M, L, D, v_c-v_n, P_n, N_r, hとともに、計算したQ_Eを記す。表１におけるQ_E値を横軸に、結晶化度を縦軸に記したものが図４である。
＜比較例＞
[1] Q値
式(1)で与えられるQ値は特許文献５で示されているものである。実施例と同一の実験に対してこのQ値を計算したものを比較例とし、表１に記載した。その際、最大せん断速度γ[・]は式(3)を用いた。その際、滞留時間τ[sec]としては、

Table 1 shows the calculated Q _E along with n, M, L, D, v _c -v _n , P _n , N _r , h. FIG. 4 shows the _QE value in Table 1 on the horizontal axis and the crystallinity on the vertical axis.
<Comparative example>
[1] Q value The Q value given by equation (1) is shown in Patent Document 5. The Q value calculated for the same experiment as the example was used as a comparative example, and is listed in Table 1. At that time, formula (3) was used for the maximum shear rate γ[·]. At that time, the residence time τ[sec] is

を用いた。ただし、吐出量は1秒あたりのグラム数として得たものである。Q値を各条件について表１にまとめた。表１におけるQ値を横軸に、結晶化度を縦軸に記したものが図５である。
[2] アミロース／脂質複合体の割合
本発明による方法によらず、加水と加熱により糊化させた後に乾燥させ粉砕することで製造されたアルファ化米粉の代表としてアルファ化米粉J（フライスター社製）の広角X線回折の実験結果を図６に示す。上記＜実施例＞[4]に記載の方法でこのX線回折の実験結果から求めたアミロース／脂質複合体の割合は1.3%であった。この結果を表２に実施例、参考例、とともにまとめた。
＜参考例＞
参考例として、粗粉砕した原料米を加熱せん断型粉砕機による処理前の原料米として考え評価した。結晶化度は上記[3]に記載の方法で求めた。アミロース／脂質複合体の割合は上記[4]に記載の方法で求めた。それぞれの結果を、表１、表２に記載した。

was used. However, the discharge amount is obtained as grams per second. The Q values are summarized in Table 1 for each condition. FIG. 5 shows the Q value in Table 1 on the horizontal axis and the crystallinity on the vertical axis.
[2] Proportion of amylose/lipid complex Pregelatinized rice flour J (Frystar Co., Ltd. Figure 6 shows the experimental results of wide-angle X-ray diffraction of The proportion of amylose/lipid complex determined from the results of this X-ray diffraction experiment using the method described in <Example> [4] above was 1.3%. The results are summarized in Table 2 together with Examples and Reference Examples.
<Reference example>
As a reference example, coarsely ground raw rice was considered and evaluated as raw rice before being processed by a heated shear type pulverizer. The crystallinity was determined by the method described in [3] above. The amylose/lipid complex ratio was determined by the method described in [4] above. The respective results are shown in Tables 1 and 2.

以上に記載した、実施例、比較例、参考例を検討すると本発明の骨子を以下のようにまとめることができる。図４から、Q_E値の増加に伴い結晶化度が減少し非晶質化が進むことが分かる。参考例となるQ_E＝０の結晶化度も図４のプロットにおいて他のデータとともにおよそ一つの直線上に位置することがわかる。これらは、本手法においてQ_E値が結晶化度の優れた制御パラメータであることを示している。一方で比較例である特許文献５のQ値で結晶化度をまとめた図５においては、結晶化度はQ値の増加関数となる領域があることが分かる。特許文献５では結晶化度がQ値の減少関数として示されており、本発明の範囲では、特許文献５の発明で満たされる傾向とは明らかに異なることが分かる。さらに参考例となるQ=0の結晶化度はその他のデータを線型的に回帰して求めた直線からは大きく外れることが分かる。これは、特許文献５のQ値が粉砕機構の回転軸と材料の流れが垂直となる臼を用いた結果を基盤とし材料の粉砕部における充填率を考慮していないのに対し、本手法のQ_Eが回転軸と材料の流れが平行となる粉砕機構における充填率の重要性を鑑みた結果である。

Examining the Examples, Comparative Examples, and Reference Examples described above, the gist of the present invention can be summarized as follows. From FIG. 4, it can be seen that as the _QE value increases, the degree of crystallinity decreases and the amorphization progresses. It can be seen that the crystallinity of Q _E =0, which is a reference example, is also located on approximately one straight line along with other data in the plot of FIG. These show that the _QE value is an excellent control parameter for crystallinity in this method. On the other hand, in FIG. 5, which summarizes the crystallinity by the Q value of Patent Document 5, which is a comparative example, it can be seen that there is a region where the crystallinity is an increasing function of the Q value. In Patent Document 5, the degree of crystallinity is shown as a decreasing function of the Q value, and it can be seen that within the scope of the present invention, the tendency is clearly different from the tendency satisfied by the invention of Patent Document 5. Furthermore, it can be seen that the crystallinity of Q=0, which is a reference example, deviates significantly from the straight line obtained by linearly regressing other data. This is because the Q value of Patent Document 5 is based on the result of using a mortar in which the rotational axis of the crushing mechanism and the flow of material are perpendicular, and does not take into account the filling rate in the crushing part of the material, whereas the Q value of this method This is a result considering the importance of the filling rate in a crushing mechanism where _QE is parallel to the rotation axis and the material flow.

Furthermore, it can be seen from the results in Table 2 that the low crystallinity rice flour obtained by this method using heat-shear type pulverization has a lower proportion of amylose/lipid complexes than that produced by the conventional method. This is due to the fact that, according to this method, there is not enough water during heating, and the molecular movement to form a composite does not occur sufficiently. It can be said to be a feature.

1 Cylinder part
2 First screw
2a Full flight part of the first screw on the inlet side
2b Starting point of the kneading part of the first screw
2c End point of the kneading part of the first screw
2d Full flight part of the first screw on the discharge port side
3 Second screw
3a Full flight part of second screw inlet side
3b Starting point of the kneading part of the second screw
3c End point of second screw kneading part
3d Full flight part of the second screw on the discharge port side
4 Center of rotation of the first screw
5 Center of rotation of the second screw
6 Clearance between kneading part and cylinder 1
7 Direction of raw material flow
8 Upper mill
9 Lower mill
10 Inlet
11 Center of rotation of lower mill
12 Arrows indicating an example of material flow direction
13 Arrows showing an example of material flow direction
14 gap

Claims (2)

A method for producing pregelatinized starch powder using a heated shear pulverizer having a structure in which the rotating axis of the pulverizing mechanism and the flow of raw material grains are parallel to each other, the method comprises:

A method for producing pregelatinized starch powder, in which the _QE value given by is 400 or more , and the pregelatinized starch powder is produced by amorphization that proceeds without adding water during heating . The method for producing pregelatinized starch powder according to claim 1, wherein the Q _E value is 600 or more.

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