Method for enriching γ-aminobutyric acid

Abstract

To provide a method for efficiently enriching GABA to wheat flour relatively low in ash amount.SOLUTION: A method for efficiently producing GABA-enriched wheat flour from low-ash wheat flour having an ash content of X mass% (X≤0.65), comprises: adding high ash wheat flour having an ash content of Y mass% (Y≥0.65 and Y≥X+0.20) to the low-ash wheat flour to produce ash-adjusted wheat flour in which the ash content is Z mass% (Z≤1.20); and adding water thereto and stirring them to generate GABA. The method solves the above problem.SELECTED DRAWING: None

Description

Technical Field

[0001] The present invention relates to a method for enriching wheat flour with γ-aminobutyric acid.

Background Art

[0002] γ-Aminobutyric acid (Gamma Amino Butyric Acid (GABA)) is an amino acid that exhibits neurotransmitter activity and is biosynthesized from glutamate by glutamate decarboxylase (GABA synthase) in vivo. Physiological effects such as blood pressure lowering effects and mental stabilization effects (anti-stress effects) have been reported for this GABA (Non-Patent Document 1). Currently, many GABA-related foods are commercially available, but their raw material prices are extremely high. As an example of a conventional production method of GABA, a method of separating germ from germinated rice and immersing the germ in water at about 20 to 40°C for 2 to 12 hours can be mentioned (Patent Document 1). Another example of a production method is a method of steaming polished rice, attaching Monascus spores to its surface, and culturing at about 30°C for 7 days (Patent Document 2). Since the purification of GABA is laborious and expensive, there is a problem that products enriched with GABA are costly. Conventionally, proposals have been made for methods of efficiently using GABA originally contained in foods or generating GABA in the food production process to efficiently enrich GABA. For example, Patent Document 3 proposes a method of preparing a dough by adding glutamate or the like to the whole grain powder of grains containing germ and husk, then adding water and kneading, and generating 10 mg or more of γ-aminobutyric acid per 100 g of the dough. However, in this method, since the GABA-rich product is generated as a dough, it cannot be used for applications such as tempura flour and fried foods, and the applications for secondary processing are limited. In addition, germ and husk contain a large amount of ash content, which causes problems such as astringency. In Patent Document 4, a method is proposed for producing a product with high nutritional value and enriched GABA by separating wheat with a high magnesium content and using its flour to produce a processed product. Since there is a correlation between the magnesium content and ash content in wheat, the ash content tends to be high in wheat with a high magnesium content, and the bran content also increases.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Patent Document 2

Patent Document 3

Patent Document 4

Non-Patent Documents

[0004]

Non-Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] The problem of the present invention is to provide a method for efficiently enriching GABA in wheat flour with a relatively low ash content. Another problem of the present invention is to provide wheat flour with a relatively low ash content and a high GABA content per gram of ash.

Means for Solving the Problems

[0006] Two or more types of wheat flour with different ash contents are mixed to produce ash-adjusted wheat flour with a certain ash content. By adding water to this and stirring, it has been found that the increase rate of GABA per unit ash content is higher than the sum of the increase rates of GABA in each of the wheat flours before mixing. In particular, it has been found that the increase rate of GABA per unit ash content is high in wheat flour with a relatively low ash content, and the present invention has been completed. The present invention includes the following inventions. 〔1〕A method for efficiently producing wheat flour enriched with GABA from low-ash wheat flour having an ash content of X mass% (X ≤ 0.65), comprising adding high-ash wheat flour having an ash content of Y mass% (Y ≥ 0.65 and Y ≥ X + 0.20) to the low-ash wheat flour to produce ash-adjusted wheat flour adjusted so that the ash content is Z mass% (Z ≤ 1.20), adding water to this and stirring to generate GABA. 〔2〕The method according to 〔1〕 above, wherein the amount of the low-ash wheat flour is in the range of 20 to 90 mass% based on the mass of the ash-adjusted wheat flour. 〔3〕The method according to 〔1〕 or 〔2〕 above, for producing wheat flour containing 18 mg or more of GABA per 1 g of ash. 〔4〕The method according to any one of 〔1〕 to 〔3〕 above, wherein the increase amount of GABA per 1 g of ash (the value obtained by subtracting the amount of GABA in the raw material wheat flour from the amount of GABA in the wheat flour after the GABA generation reaction) is 12 mg or more. 〔5〕The method according to any one of 〔1〕 to 〔4〕 above, wherein the GABA content of the low-ash wheat flour having an ash content of X mass% (X ≤ 0.65) is 4.0 mg / 100 g or less, and the GABA content of the high-ash wheat flour having an ash content of Y mass% (Y ≥ 0.65 and Y ≥ X + 0.20) is 4.0 mg / 100 g or more. 〔6〕The method according to any one of 〔1〕 to 〔5〕 above, wherein the step of adding water to the ash-adjusted wheat flour and stirring is a step of adding 33 mass parts or less of water to 100 mass parts of the ash-adjusted wheat flour and stirring. 〔7〕Wheat flour enriched with GABA, having an ash content of Z1 mass% (0.40 ≤ Z1 ≤ 1.00) and containing 20 mg or more of GABA per 1 g of ash.

Advantages of the Invention

[0007] By using the method of the present invention in which two or more types of low-ash and high-ash wheat flours are combined, compared with the method using a single wheat flour (fraction) with the same amount of ash content, wheat flour with a higher GABA content (per ash content) can be obtained. This is presumably because the concentration of GABA synthase could be increased. Since the product of the present invention has a low ash content relative to the GABA content, it is possible to provide a wheat flour product enriched with GABA while suppressing astringency. Also, by using the method of the present invention in which two or more types of low-ash and high-ash wheat flours are combined, compared with the case where the low-ash and high-ash wheat flours (fractions) before combination are each reacted alone, the increase in GABA amount per ash content (the amount obtained by subtracting the GABA amount before the reaction from the GABA amount after the reaction) can be increased, and wheat flour enriched with GABA can be efficiently produced. Furthermore, according to the present invention, since it is possible to provide wheat flour with a high GABA content rather than a dough-like product, it can be applied to various products enriched with GABA.

Mode for Carrying Out the Invention

[0008] The first aspect of the present invention is the following method. A method for efficiently producing GABA-enriched wheat flour from low-ash wheat flour having an ash content of X mass% (X ≤ 0.65), comprising adding high-ash wheat flour having an ash content of Y mass% (Y ≥ 0.65 and Y ≥ X + 0.20) to the low-ash wheat flour to produce ash-adjusted wheat flour adjusted so that the ash content becomes Z mass% (0.4 ≤ Z ≤ 1.2), adding water thereto and stirring to generate GABA. Hereinafter, it is also referred to as the "GABA enrichment method".

[0009] By combining two or more types of low-ash and high-ash flours, a flour with a higher GABA content and concentration of GABA synthase can be obtained compared to flours with the same ash content. Further, after mixing with water and drying, and manufacturing flour again, a flour with a higher GABA content can be produced. Since the product of the present invention has a low ash content relative to the GABA content, it is a flour enriched with GABA while suppressing astringency.

[0010] The flour used in the method for enriching GABA of the present invention may be any of strong flour, medium flour, weak flour, whole grain flour, durum wheat flour, etc., and is not particularly limited. In the present invention, the "low-ash flour having an ash content of X mass% (X ≤ 0.65)" may be any as long as the ash content measured by the ash measurement method described below is 0.65 mass% or less. For example, among 40 to 50 types of overflours obtained by a stepwise flour milling method, the ash content is 0.30 to 4.00 mass%, and one fraction with an ash content of 0.65 mass% or less may be selected from the overflours, or a flour with an arbitrary ash content may be prepared by mixing two or more types. Further, ordinary flour with an ash content of 0.30 to 2.00 mass% may be separated by particle size by classification and obtained as a fraction with an ash content of 0.65 mass% or less. X is preferably 0.60 or less, more preferably 0.50 or less, and even more preferably 0.40 or less. Further, as the lower limit value of X, it is preferably 0.20 or more, and more preferably 0.30 or more. The "low-ash flour having an ash content of X mass% (X ≤ 0.65)" of the raw material used in the method for enriching GABA of the present invention is more preferably a fraction having an ash content of 0.65 mass% or less obtained by the above-described known method, and preferably has a GABA content of 4.0 mg / 100 g or less, more preferably 3.5 mg / 100 g or less, even more preferably 2.0 mg / 100 g or less, and even more preferably 1.0 mg / 100 g or less.

[0011] In the present invention, the "high-ash wheat flour having an ash content of Y mass% (Y ≧ 0.65 and Y ≧ X + 0.20)" may be any one as long as the measured ash content Y measured by the ash measurement method described below is 0.65 mass% or more and satisfies Y ≧ X + 0.20 with respect to the ash content X of the low-ash wheat flour. For example, it may be obtained as a fraction having an ash content of 0.65 mass% or more from bran. Also, ordinary wheat flour having an ash content of 0.30 to 2.00 mass% may be classified by particle size and obtained as a fraction having an ash content of 0.65 mass% or more. Y is preferably 0.80 or more, more preferably 0.90 or more, still more preferably 1.00 or more, and even more preferably 1.10 or more (for example, 1.20 or more). Also, as the upper limit value of Y, it is preferably 2.80 or less, more preferably 2.00 or less, and still more preferably 1.50 or less. The "high-ash wheat flour having an ash content of Y mass% (Y ≧ 0.65 and Y ≧ X + 0.20)" of the raw material used in the GABA enrichment method of the present invention is more preferably a fraction having an ash content of 0.65 mass% or more obtained by the above-described known method, and preferably has a GABA content of 4.0 mg / 100 g or more, more preferably 5.0 mg / 100 g or more, still more preferably 9.0 mg / 100 g or more, and even more preferably 15 mg / 100 g or less.

[0012] In the present invention, the ash content X mass% and Y mass% of the "low-ash wheat flour" and the "high-ash wheat flour" are preferably Y ≧ X + 0.30, more preferably Y ≧ X + 0.40, still more preferably Y ≧ X + 0.50, and even more preferably Y ≧ X + 0.60 from the viewpoint of the effect.

[0013] The GABA enrichment method of the present invention includes adding high-ash wheat flour to the above low-ash wheat flour to produce ash-adjusted wheat flour adjusted so that the ash content is Z mass% (Z ≦ 1.20), adding water thereto and stirring to generate GABA. By adjusting the ash content Z of the ash-adjusted wheat flour to 1.20% by mass or less, the low-ash wheat flour and the high-ash wheat flour are mixed within an appropriate range, and the production amount of the GABA amount per 1 g of ash can be efficiently increased. It is preferable that Z satisfies 0.40 ≦ Z ≦ 1.00, more preferably 0.50 ≦ Z ≦ 0.90, still more preferably 0.50 ≦ Z ≦ 0.80, and even more preferably 0.50 ≦ Z ≦ 0.65.

[0014] The mixing ratio (mass ratio) of the low-ash wheat flour to the high-ash wheat flour is preferably 5:95 to 95:5, more preferably 20:80 to 90:10, and still more preferably 30:70 to 80:20. In the method for enriching GABA of the present invention, the amount of the low-ash wheat flour is preferably in the range of 20 to 90% by mass based on the mass of the ash-adjusted wheat flour. More preferably, it is in the range of 30 to 80% by mass. It may be in the range of 40 to 80% by mass, or may be in the range of 50 to 80% by mass.

[0015] By the method for enriching GABA of the present invention, for example, wheat flour containing 18 mg or more of GABA per 1 g of ash can be produced. In the experiments of the present inventors, when GABA was produced using only a low-ash wheat flour having an ash content of 0.65% by mass or less, the GABA content was at most about 17 mg per 1 g of ash. In the method for enriching GABA of the present invention, the amount of GABA per 1 g of ash in the produced wheat flour is preferably 19 mg or more, more preferably 20 mg or more, still more preferably 23 mg or more, and even more preferably 25 mg or more.

[0016] By the method for enriching GABA of the present invention, the increase amount of GABA per 1 g of ash (the value obtained by subtracting the amount of GABA in the raw material wheat flour from the amount of GABA in the wheat flour after the GABA production reaction) is preferably 12 mg or more, more preferably 13 mg or more, still more preferably 15 mg or more, and even more preferably 16 mg or more. In the experiments of the present inventors, when GABA was produced using the low-ash wheat flour or high-ash wheat flour of the present invention alone, the maximum increase in GABA was 11.4 mg per 1 g of ash content.

[0017] In the method for enriching GABA of the present invention, water is added to the ash-adjusted wheat flour and stirred to produce GABA. The GABA synthase is activated by water to produce GABA. The amount of water is not particularly limited, but it is preferably a step of adding 33 parts by mass or less of water to 100 parts by mass of the ash-adjusted wheat flour and stirring. Although it is considered that the larger the amount of water relative to 100 parts by mass of the ash-adjusted wheat flour, the greater the amount of GABA produced, it is not preferable because it will become dough-like when it exceeds 33 parts by mass and the powdery state called wheat flour cannot be maintained. More preferably, 5 parts by mass or more and 25 parts by mass or less of water is added.

[0018] When adding water, it is preferable to mix so that the moisture is uniform. Since the method of mixing only needs to ensure that the moisture is evenly distributed, the method can be arbitrarily selected. The temperature during mixing is not a problem as long as the enzyme is not inactivated, so it may be 10°C or higher and 65°C or lower, preferably 20°C or higher and 60°C or lower, but more preferably 35°C or higher and 45°C or lower, which is the optimum temperature of the enzyme. After adding water, it is preferable to keep it warm at a certain temperature (10°C or higher and 65°C or lower, preferably 20°C or higher and 60°C or lower, more preferably 35°C or higher and 45°C or lower) for about 5 to 300 minutes (preferably about 30 to 240 minutes).

[0019] After heat preservation, it is preferable to dry it or dry it while keeping it warm at a constant temperature. Drying is preferable because it is possible to produce powdery wheat flour instead of dough-like. It is considered that the increase in the amount of GABA produced occurs by standing at the optimum temperature of glutamate decarboxylase for an arbitrary time.

[0020] In this specification, the amount of "ash" in wheat flour may be measured by any conventionally known method. For example, using a combustion aid or the like, the weighed sample is incinerated in a crucible, cooled to room temperature in a desiccator, and then weighed to measure the amount of ash per unit mass of wheat flour.

[0021] In this specification, the amount of "GABA" in wheat flour may be measured by any conventionally known method. For example, GABA is extracted from wheat flour using a solvent such as an aqueous ethanol solution, the extract is dried, and then made up to a fixed volume with distilled water, and analyzed by, for example, HPLC by the calibration curve quantification method using a standard product of amino acids.

[0022] A second aspect of the present invention is wheat flour enriched with GABA, which has an ash content of Z1 mass% (0.40 ≦ Z1 ≦ 1.00) and contains 20 mg or more of GABA per 1 g of ash. In the second aspect, it is more preferable that Z1 is 0.50 ≦ Z1 ≦ 0.90, still more preferable that 0.50 ≦ Z1 ≦ 0.80, and even more preferable that 0.50 ≦ Z1 ≦ 0.65. The amount of GABA per 1 g of ash is more preferably 22 mg or more, still more preferably 23 mg or more, and even more preferably 25 mg or more. Such wheat flour enriched with GABA can be produced by the above-described GABA enrichment method.

[0023] The relatively low-ash wheat flour enriched with GABA produced by the method of the present invention has a high concentration of GABA synthase, so by adding it to foods containing glutamic acid such as tomatoes and cheese, it is possible to produce products with a high GABA content.

Examples

[0024] <Method for measuring the ash content in wheat flour> The ash content (g / 100 g) in each wheat flour sample was analyzed as follows. 40 g of magnesium acetate tetrahydrate (special grade) was added with 300 ml of distilled water and 6 ml of acetic acid (special grade), stirred well until dissolved, and methanol (special grade) was added to make up to 3 L to prepare a combustion aid. 5 g of wheat flour sample was weighed into a crucible. 5 ml of the combustion aid was added, ignited, pre-baked for 90 minutes, and then ashed at 800 °C for 90 minutes. After cooling to room temperature in a desiccator, it was weighed, and the ash content per 100 g of wheat flour was calculated.

[0025] <Method for measuring the amount of GABA in wheat flour> The amount of GABA (mg / 100 g) in each wheat flour sample was analyzed as follows. 90 ml of 75% (v / v) ethanol aqueous solution was added to 3 g of wheat flour sample, stirred and extracted, and then filtered using filter paper to obtain an extract. The extract was dried to dryness with an evaporator and made up to 15 ml with distilled water. The made-up extract was filtered through a 0.45 μm membrane filter, and the supernatant obtained by centrifuging the filtrate at 5000 rpm for 10 minutes was ultrafiltered with Amicon Ultra (molecular weight 3000), and the filtrate was used as a test solution for HPLC analysis. Analysis and quantification were performed using an amino acid analyzer L-8900 manufactured by Hitachi High-Tech Corporation as an HPLC analyzer. The eluent was a buffer solution for biological fluid analysis manufactured by Kanto Chemical Co., Inc., and the post-column reaction solution was a kit for amino acid automatic analyzer using ninhydrin reagent Wakopak amino acid kit manufactured by Fujifilm Wako Pure Chemical Corporation. For quantification, an amino acid mixed standard solution, L-asparagine, L(+)-glutamine, and L-tryptophan manufactured by Fujifilm Wako Pure Chemical Corporation were used, and the amount of GABA was analyzed by the calibration curve quantification method.

[0026] [Test Example 1] Using the wheat flour of Test Example 1 shown in Table 1 below as a raw material, as shown in Table 2, only the water addition amount was changed in the range of 5 parts by mass or more and 25 parts by mass or less (the amount of wheat flour was adjusted so that the total of wheat flour and water was 100 parts by mass), and stirred at room temperature for 10 minutes with a food processor to conduct a GABA production test. In this test, the amount of GABA was measured immediately after stirring for 10 minutes. The amount of GABA increased approximately proportionally to the water addition amount. Although increasing the amount of added water increases GABA, GABA also increased even when the amount of added water was 5 parts by mass. On the other hand, when no water was added (0 parts by mass of added water), there was no change in the amount of GABA (Table 2). As the amount of added water increased, the wheat flour was granulated (becoming like a part of the dough), losing uniformity and resulting in a state where fine granular substances like dough were mixed. The ratio of wheat flour to water was approximately uniform from 95:5 to 75:25, but became non-uniform at 70:30, and the extraction during GABA measurement did not go well. In the following examples, a ratio of 80:20, which results in a large amount of GABA and high uniformity, was used as a standard.

[0027] Table 1 TIFF0007697806000001.tif26139

[0028] Table 2 Comparison by Amount of Added Water TIFF0007697806000002.tif21122

[0029] [Test Example 2] Among the preparation conditions of Test Example 1, the water addition condition was changed to 15 parts by mass of water at 25 °C for 85 parts by mass of wheat flour. After stirring at room temperature for 10 minutes with a food processor, it was further kept warm at the temperature and time shown in Table 3, and then the amount of GABA was measured. The holding temperature is the temperature of the constant temperature bath, not the temperature of the wheat flour. By adding the holding time at 40 °C, the amount of GABA increases, but the amount of GABA also increases sufficiently by stirring at room temperature for 10 minutes. Therefore, in the following examples, stirring at room temperature for 10 minutes was used as the standard method.

[0030] Table 3 Comparison by Additional Holding Temperature and Time TIFF0007697806000003.tif21155

[0031] [Examples 1 - 9 and Comparative Example 1] <Production Example 1> Wheat flours L1, L2, H1, H2, and H3 described in Table 4 were produced by mixing two or more types from the offal obtained in the milling process. Table 4 TIFF0007697806000004.tif15137

[0032] <Production Example 2> The wheat flours L1, L2, H1, H2, and H3 in Table 4 were mixed at the mixing ratios described in Tables 6-1 to 6-3 to produce wheat flours with respective ash contents (Examples 1 to 9 and Comparative Example 1). The ash contents of the respective wheat flours were measured by the method described above (Tables 6-1 to 6-3).

[0033] <Test 1> For each of the wheat flours in Table 4 and the wheat flours in Tables 6-1 to 6-3, 20 parts by mass of water at a water temperature of 25°C was added to 80 parts by mass of the wheat flour, and after stirring at room temperature for 10 minutes with a food processor, it was dried in a constant temperature bath at 60°C for 60 minutes. For each of the processed wheat flours, the amount of GABA before adding water and the amount of GABA after the reaction were measured by the method described above. Each numerical value in Tables 5 and 6-1 to 6-3 means the following. "Ash content (g / 100g)": The amount of ash (g) per 100 g of each wheat flour. "Amount of GABA before reaction (R1) (mg / 100g)": The amount of GABA (mg) per 100 g of the wheat flour before adding water to each wheat flour. "Amount of GABA after reaction (R2) (mg / 100g)": The amount of GABA (mg) per 100 g of the wheat flour after reacting each wheat flour under the conditions of Test 1. "Amount of GABA after reaction (R2) / ash content (mg / g)": The value obtained by dividing "amount of GABA after reaction (R2) (mg / 100g)" by the "ash content (g / 100g)" of each wheat flour. "Increase in GABA amount (R2 - R1) (mg / 100g)": The value obtained by subtracting "amount of GABA before reaction (R1) (mg / 100g)" from "amount of GABA after reaction (R2) (mg / 100g). "Increase in GABA amount (R2 - R1) / ash content (mg / g)": The value obtained by dividing "increase in GABA amount (R2 - R1) (mg / 100g)" by the "ash content (g / 100g)" of each wheat flour. "Reference GABA amount before reaction (C1) (mg / 100g)": It is the value obtained by multiplying the "GABA amount before reaction (R1) (mg / 100g)" of each of the wheat flours L1, L2, H1, H2, and H3 described in Table 5 by the mixing ratio and calculating the value of the "GABA amount before reaction (R1) (mg / 100g)" based on the mixing ratio of each wheat flour used in the combination, and then adding them together. "Reference GABA amount after reaction (C2) (mg / 100g))": It is the value obtained by multiplying the "GABA amount after reaction (R2) (mg / 100g)" of the wheat flours L1, L2, H1, H2, and H3 described in Table 5 by the mixing ratio and calculating the value of the "GABA amount after reaction (R2) (mg / 100g)" based on the mixing ratio of each wheat flour used in the combination, and then adding them together. "Reference GABA amount after reaction (C2) / ash content (mg / g)": It is the value obtained by dividing the "Reference GABA amount after reaction (C2) (mg / 100g))" by the "ash content (g / 100g)" of each wheat flour. "Reference GABA increase amount (C2 - C1) (mg / 100g)": It is the value obtained by subtracting the "Reference GABA amount before reaction (C1) (mg / 100g)" from the "Reference GABA amount after reaction (C2) (mg / 100g))". "Reference GABA increase amount (C2 - C1) / ash content (mg / g)": It is the value obtained by dividing the "Reference GABA increase amount (C2 - C1) (mg / 100g)" by the "ash content (g / 100g)" of each wheat flour.

[0034] Table 5 Unmixed wheat flour TIFF0007697806000005.tif36134

[0035] Table 6-1 Mixed wheat flour TIFF0007697806000006.tif78151

[0036] Table 6-2 Mixed wheat flour TIFF0007697806000007.tif88162

[0037] Table 6-3 Mixed wheat flour TIFF0007697806000008.tif73145

[0038] As can be seen from Table 6-1, when the same low-ash wheat flour was used and adjusted so that the final ash content was the same, the GABA production amounts ("GABA amount after reaction (R2)" and "GABA production amount (R2 - R1)") differed depending on the ash content of the high-ash wheat flour used. Also, in any combination, the GABA production amount was higher than when using only L2 with the same ash content (0.60 g / 100 g) (0.60 mass%). Among Examples 1 to 3, the one with the largest final GABA amount and also the highest value in terms of the GABA increase amount was Example 3 (L1 + H3), followed by Example 2 (L1 + H2). The same tendency can also be read from Table 6-2. Furthermore, from Table 6-2, it was found that when adjusted so that the final ash content was the same, the results also differed depending on the ash content of the low-ash wheat flour. That is, when comparing Example 4 (L1 + H2) and Example 6 (L2 + H2), or Example 5 (L1 + H3) and Example 7 (L2 + H3), although slightly, the GABA production amounts ("GABA amount after reaction (R2)" and "GABA production amount (R2 - R1)") were higher when using L1 with a lower ash content in Examples 4 and 5. The same tendency can also be read from Table 6-3. From the above, it is better to use L1 rather than L2 as the low-ash wheat flour to be combined, and in the case of the high-ash wheat flour, it is best to use H3, followed by H2 and H1.

[0039] As can be seen from Tables 6-1 to 6-3, focusing on the ash content to be adjusted, the higher the ash content, the more the GABA production amount increases. However, when compared with the "GABA amount after reference reaction (C2)" or "reference GABA increase amount (C2 - C1)" calculated based on the mixing ratio of the GABA production amounts when each of the raw wheat flours was reacted alone, the lower the ash content, the greater the difference and the higher the increase rate (the higher the production efficiency). For example, in Example 3 (L1 + H3, adjusted ash content 0.60 g / 100 g), the GABA increase amount (R2 - R1) / ash is 17.7 mg / g, while the reference GABA increase amount (C2 - C1) / ash is 10.8 mg / g, so the difference is "6.9 mg / g". In contrast, in Example 5 (L1 + H3, adjusted ash content 0.80 g / 100 g), the GABA increase amount (R2 - R1) / ash is 16.8 mg / g, while the reference GABA increase amount (C2 - C1) / ash is 13.4 mg / g, so the difference is "3.4 mg / g". As can be seen from Table 6-3, when low-ash wheat flour having an ash content of X mass% (X ≤ 0.65) was not used (Comparative Example 1), the GABA production amounts ("GABA amount after reaction (R2)" and "GABA production amount (R2 - R1)") were almost the same as the GABA production amounts ("GABA amount after reference reaction (C2)" and "reference GABA increase amount (C2 - C1)") calculated based on the mixing ratio of the GABA production amounts when each of the raw wheat flours was reacted alone, so the significance of combination is small.

Claims

1. A method for producing GABA - enriched wheat flour from low - ash wheat flour having an ash content of X mass% (X ≤ 0.65), comprising adding high - ash wheat flour having an ash content of Y mass% (Y ≥ 0.65 and Y ≥ X + 0.20) to the low - ash wheat flour to produce ash - adjusted wheat flour adjusted so that the ash content is Z mass% (Z ≤ 1.20), adding water thereto and stirring to generate GABA.

2. The method according to claim 1, wherein the amount of the low - ash wheat flour is in the range of 20 to 90 mass% based on the mass of the ash - adjusted wheat flour.

3. The method according to claim 1 or 2, for producing wheat flour containing 18 mg or more of GABA per gram of ash.

4. The method according to any one of claims 1 to 3, wherein the increase amount of GABA per gram of ash (the value obtained by subtracting the amount of GABA in the raw material wheat flour from the amount of GABA in the wheat flour after the GABA - generating reaction) is 12 mg or more.

5. The method according to any one of claims 1 to 4, wherein the GABA content of the low - ash wheat flour having an ash content of X mass% (X ≤ 0.65) is 4.0 mg / 100 g or less, and the GABA content of the high - ash wheat flour having an ash content of Y mass% (Y ≥ 0.65 and Y ≥ X + 0.20) is 4.0 mg / 100 g or more.

6. The method according to any one of claims 1 to 5, wherein the step of adding water to the ash - adjusted wheat flour and stirring is a step of adding 33 parts by mass or less of water to 100 parts by mass of the ash - adjusted wheat flour and stirring.

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