Flour inspection methods

Abstract

To provide an inspection method that enables simple and quick detection of chemicals contained in grain powder.SOLUTION: A grain powder inspection method that clears the above challenge is provided, the method comprising forming a grain powder layer with a flat surface by placing grain powder on a substrate and pressing a flat plate against the grain powder, and applying a reagent solution on the flat surface of the grain powder layer for reaction. The reagent solution consists of a detection reagent that develops color or emits light when reacting with chemicals, and a solvent having a surface tension of 50 mN / m or less.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a method for testing chemical substances contained in cereal flour. [Background technology]

[0002] Flour obtained by milling grains can contain various chemicals, including bleaching agents used to color the flour white, pesticides sprayed before harvest, and mold and insecticides sprayed after harvest. Because flour is processed into various foods and feeds, strict limits are imposed on the amount of these chemicals that can be contained or used. For example, benzoyl peroxide is an additive used as a flour improver. The Ministry of Health, Labour and Welfare (MHLW) established the ingredient specifications for "diluted benzoyl peroxide" (benzoyl peroxide diluted with calcium phosphate or calcium carbonate to a benzoyl peroxide content of 19.0-35.0% by mass) in its "Standards and Criteria for Foods, Food Additives, etc. (Ministry of Health and Welfare Notification No. 370, December 28, 1959)" based on the Food Sanitation Act, and stipulated a usage limit of 0.30 g (300 ppm) or less of "diluted benzoyl peroxide" per kg of flour. Measuring the content of these chemicals in grain flour requires pretreatment, such as extraction and labeling, which requires the use of various analytical instruments such as liquid chromatography and gas chromatography, which is cumbersome and takes time to obtain results. On the other hand, at manufacturing sites, etc., there is a demand for preliminary testing for the presence or absence of chemical substances in grain flour as a step before conducting strict measurements using instrumental analysis. For example, the above-mentioned benzoyl peroxide is often used in imported wheat flour, and according to the benzoyl peroxide analysis method in the Ministry of Health, Labor and Welfare's notification "Method for Analyzing Food Additives in Foods" based on the Food Sanitation Act, analysis must be done by liquid chromatography, but there has been a demand for a method that can detect it quickly and simply at manufacturing sites.

[0003] The Pecker test is generally known as a method for visually inspecting the color tone of cereal flour rather than by instrumental analysis. In this method, flour is placed on a glass plate such as a glass slide, sandwiched between another glass plate, immersed in water to the extent that the water penetrates the flour sandwiched between the glass plates, and then removed from the water and inspected visually. There are examples where this Pecker test has been used to check the uneven distribution of different powders and particles added to and mixed with flour (Patent Document 1), but there have been no examples where it has been applied to inspecting chemical substances contained in flour. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2000-128102 [Non-patent literature]

[0005] [Non-Patent Document 1] Lunkenheimer, K.; Wantke, KD Colloid Polym. Sci., 1981,259,p.354-366. Summary of the Invention [Problem to be solved by the invention]

[0006] An object of the present invention is to provide a testing method that can easily and quickly detect chemical substances contained in cereal flour. [Means for solving the problem]

[0007] As a result of extensive research into solving the above-mentioned problems, the inventors have discovered that chemical substances contained in grain flour can be visually detected simply and quickly without the use of special measuring equipment or complicated chemical substance extraction procedures, by a method which includes the steps of placing grain flour on a substrate and pressing a flat plate against the flour to form a grain flour layer with a flat surface, and applying a reagent solution to the flat surface of the grain flour layer, wherein the reagent solution consists of a detection reagent that reacts with the chemical substance to develop color or light, and a solvent, and the surface tension of the solvent is 50 mN / m or less, and which has led to the completion of the present invention.

[0008] That is, the present invention includes the following aspects. [1] A method for detecting chemical substances contained in cereal flour, comprising the steps of placing cereal flour on a substrate and pressing a flat plate against the cereal flour to form a cereal flour layer with a flat surface, and applying a reagent solution to the flat surface of the cereal flour layer, wherein the reagent solution comprises a detection reagent that reacts with the chemical substance to produce a color or emit light, and a solvent, and the surface tension of the solvent is 50 mN / m or less. [2] The detection method described in [1], wherein the chemical substance contained in the cereal flour is an oxidizing substance and the detection reagent is a reducing detection reagent. [3] The detection method according to [2], wherein the oxidizing substance is one or more selected from the group consisting of benzoyl peroxide, potassium bromate, sodium sulfite, and calcium hypochlorite. [4] The detection method according to [2] or [3], wherein the reduction-based detection reagent is any one selected from the group consisting of diethyl-p-phenylenediamine, potassium iodide, o-tolidine, and syringaldazine. [5] The detection method according to any one of [1] to [4], wherein the cereal flour is wheat flour. [6] The detection method according to any one of [1] to [5], wherein the means for applying the reagent solution to the flour is dripping or spraying. [Effects of the Invention]

[0009] According to the present invention, it is possible to provide a testing method that can simply and quickly detect chemical substances contained in cereal flour. [Brief explanation of the drawings]

[0010] [Figure 1] The results of the detection of diluted benzoyl peroxide in wheat flour. (A) is wheat flour without diluted benzoyl peroxide, and (B) is wheat flour containing 250 ppm of diluted benzoyl peroxide. [Figure 2] Detection of diluted benzoyl peroxide in wheat flour containing (A) 250 ppm, (B) 200 ppm, (C) 150 ppm, and (D) 100 ppm diluted benzoyl peroxide. [Figure 3] Detection of diluted benzoyl peroxide in wheat flour containing (A) 50 ppm, (B) 40 ppm, (C) 30 ppm, (D) 20 ppm, (E) 10 ppm, and (F) 0 ppm diluted benzoyl peroxide. DETAILED DESCRIPTION OF THE INVENTION

[0011] The present invention relates to a method for detecting chemical substances contained in flour, which comprises the steps of placing flour on a substrate and pressing a flat plate against the flour to form a flour layer with a flat surface, and applying a reagent solution to the flat surface of the flour layer, wherein the reagent solution comprises a detection reagent that reacts with the chemical substance to develop color or light, and a solvent, and the surface tension of the solvent is 50 mN / m or less.

[0012] In the present invention, flour refers to a powder obtained by crushing grains and recovering mainly the endosperm. Examples of grains include wheat, rice, rye, soybean, corn, etc. From the viewpoint that flours with a high protein content are more likely to form a flour layer with a flat surface as described below, wheat, rye, soybean, and corn are preferred, and wheat, soybean, and corn are more preferred.

[0013] The method of the present invention includes the steps of placing flour on a substrate and pressing a flat plate against the flour to form a flour layer with a flat surface. The substrate is not particularly limited in terms of material or shape, as long as an appropriate amount of flour can be placed thereon. For example, a plastic or glass plate, tray, dish, or the like can be used as the substrate. The amount of flour placed on the substrate is not particularly limited, and the shape and thickness of the flour layer formed do not need to be uniform, but the flour layer at least has a flat surface formed by pressing the flat plate against it. Having a flat surface in the flour layer makes it easier to visually observe the color or luminescence caused by the detection reagent. The flat plate may be a tool with a flat, plate-like portion, such as a metal spatula or a rubber spatula, or a glass plate such as a glass slide. From the viewpoint of workability, for example, 10 to 30 g of flour is mixed at 100 to 300 cm 2 The mixture is placed on a glass plate having an area of ​​100 mm, and a spatula is pressed against it to form a flour layer (thickness: about 5 to 10 mm) with a flat surface.

[0014] The method of the present invention includes a step of applying a reagent solution to the flat surface of the flour layer. In the present invention, the means for applying the reagent solution to the flat surface of the flour layer is not particularly limited, but examples include dripping or spraying the reagent solution. The amount of reagent solution applied can be adjusted as appropriate, but preferably at least 100 μl to 300 μl of reagent solution is applied to the flat surface of the flour layer, making it easy to visually observe the color or luminescence.

[0015] In the present invention, chemical substances contained in flour include flour quality improvers, such as bleaching agents used to color flour white, pesticides sprayed on the grains used to make flour before harvest, and fungicides or insecticides sprayed after harvest, which can be detected by reacting with a specific detection reagent to produce color or luminescence. Chemical substances detected by color development are preferably oxidizing substances, more preferably benzoyl peroxide, potassium bromate, sodium sulfite, and calcium hypochlorite. Chemical substances detected by luminescence include ATP.

[0016] In the present invention, the reagent solution comprises a detection reagent that reacts with the chemical substance to develop color or light and a solvent. The detection reagent is not particularly limited as long as it reacts with the chemical substance to be detected to develop color or light. For example, diethyl-p-phenylenediamine (DPD) produces quinone diimine by reacting with an oxidizing agent. The quinone diimine reacts with unreacted DPD to produce a reddish-pink diethyl-semiquinone intermediate. In other words, the presence of an oxidizing agent in the reaction system can be detected by the reddish-pink color that occurs when DPD is added. The reagent that reacts with a chemical substance to develop a color is preferably a reduction-based detection reagent that reacts with an oxidizing substance, and examples of such reduction-based detection reagents include diethyl-p-phenylenediamine, potassium iodide, o-tolidine, and syringaldazine. The reagent that reacts with the chemical to produce light is preferably luciferase.

[0017] In the present invention, the surface tension of the solvent of the reagent solution is 50 mN / m or less. When the surface tension of the solvent is within a predetermined range, the reagent solution can penetrate into the flat surface of the flour layer. It is preferably 40 mN / m or less, more preferably 30 mN / m or less, and even more preferably 25 mN / m or less. The lower the surface tension of the solvent of the reagent solution, the easier it is for the reagent solution to penetrate into the flat surface of the flour layer. There are no particular restrictions on the method for measuring surface tension, and examples include the ring method (also known as the du Nouy ring method), the hanging drop method, and the maximum bubble pressure method. For example, the surface tension at 20°C is measured according to the du Nouy ring method described in Non-Patent Document 1. The solvent for the reagent solution may be a single solvent or a mixture of multiple solvents, and a solvent that exhibits a surface tension within the above-mentioned predetermined range can be appropriately selected and used depending on the type of reagent used. Examples include lower alcohols such as methanol, ethanol, 1-propanol, 2-propanol, and 1-butanol, or aqueous solutions thereof; aqueous solutions of surfactants such as sodium lauryl sulfate; oils and fats that are liquid at room temperature such as olive oil; and diethyl ether. [Example]

[0018] EXAMPLES The present invention will be described in detail below with reference to examples, but the present invention is not limited to the following examples.

[0019] <Test Example 1: Detection of Benzoyl Peroxide> The detection of benzoyl peroxide in wheat flour was investigated using diethyl-p-phenylenediamine (DPD) as a detection reagent. 100 parts by mass of wheat flour was placed in a plastic bag, diluted benzoyl peroxide was added to a concentration of 250 ppm (0.25 g / kg), and the mixture was shaken by hand for 1 minute. Wheat flour without benzoyl peroxide was used as a control. 20 g of wheat flour containing "diluted benzoyl peroxide" and control flour were placed on a 10 cm x 20 cm glass plate and pressed down with a metal spatula to create a flat flour layer. 200 μL of a 0.05% DPD / ethanol solution (w / v) was added dropwise and allowed to stand for 3 minutes. As a result, reddish-pink spots were observed due to the reaction between DPD and benzoyl peroxide, demonstrating that "diluted benzoyl peroxide" in flour can be detected (Figure 1). Furthermore, the detection limit of diluted benzoyl peroxide was confirmed by gradually diluting the concentration of diluted benzoyl peroxide in wheat flour containing diluted benzoyl peroxide and conducting the same detection test as above. As a result, numerous well-colored reddish-pink spots were observed up to 100 ppm of diluted benzoyl peroxide, and even at 10 ppm, a sufficient number of reddish-pink spots were observed, although the color was faint (Figures 2 and 3).

[0020] <Test Example 2: Solvent Consideration 1> The type of solvent used in the reagent solution was investigated. Detection of "diluted benzoyl peroxide" in wheat flour was investigated in the same manner as in Test Example 1, except that the solvent in the DPD solution, which is the reagent solution, was changed to something other than ethanol. When lower alcohols other than ethanol, such as methanol, 1-propanol, 2-propanol, and 1-butanol, were used as the solvent, the DPD solution penetrated the flour layer in all cases, just as when ethanol was used in Test Example 1, and ``diluted benzoyl peroxide'' in the wheat flour could be detected. When an alcohol with a relatively high carbon number (1-butanol) was used as the solvent, penetration into the flour layer was sufficient, but the solubility of DPD in 1-butanol was low, and 0.05% (w / v) DPD did not completely dissolve, so the color of the reddish-pink spots was weaker than in Test Example 1, which used ethanol. Furthermore, when diethyl ether was used as the solvent, reddish-pink spots could not be detected because DPD was insoluble in diethyl ether, but the penetration of the reagent solution into the flour layer was better than when ethanol was used. This suggests that when a highly lipophilic detection reagent is used, a solvent with low hydrophilicity or a non-polar solvent can be used.

[0021] <Test Example 3: Solvent Consideration 2> Solvents listed in Table 1 were prepared using ethanol and distilled water, and the surface tension at 20°C was measured according to the du Nouy ring method described in Non-Patent Document 1. A detection test for wheat flour containing "diluted benzoyl peroxide" was conducted according to Test Example 1, except that DPD was dissolved in these solvents to prepare a 0.05% (w / v) DPD solution. The penetration of the reagent solution into the flour layer and the detection of diluted benzoyl peroxide were evaluated according to the following evaluation criteria. As a result, solvents 1 and 2 penetrated the flour layer well, and reddish-pink spots resulting from the "diluted benzoyl peroxide" could be detected. Solvents 3 and 4 penetrated the flour layer slightly slower, but the detection of reddish-pink spots was slightly inferior to solvents 1 and 2. Solvent 5 penetrated the flour layer even slower, but some reddish-pink spots resulting from the "diluted benzoyl peroxide" could be detected, suggesting that good reddish-pink spots could be detected by extending the time for solvent 5 to penetrate the flour layer. The DPD aqueous solution in solvent 6 remained as approximately hemispherical droplets without penetrating the flour layer, and the reaction between the "diluted benzoyl peroxide" and DPD did not proceed, making it impossible to detect reddish-pink spots. This indicates that surface tension is involved in the penetration of the reagent solution into the flour layer.

[0022] Table 1. Surface tension of ethanol solution, penetration of reagent solution into flour layer, and detection of diluted benzoyl peroxide TIFF0007809553000001.tif52159

[0023] Evaluation criteria TIFF0007809553000002.tif73146

[0024] <Test Example 4: Solvent Consideration 3> A detection test for wheat flour containing "diluted benzoyl peroxide" was conducted according to Test Example 1, except that the solvent for the DPD solution reagent was changed from ethanol to aqueous sodium lauryl sulfate or olive oil. The surface tension of the solvent at 20°C was measured according to the du Nouy ring method described in Non-Patent Document 1, and the penetration of the reagent solution into the flour layer and the detection of diluted benzoyl peroxide were evaluated according to the evaluation criteria in Test Example 3. As a result, penetration into the flour layer equivalent to that of solvent 4 in Test Example 3 was observed in both cases, suggesting that chemicals in flour can be detected if the surface tension is met. Since DPD dissolves in an aqueous solution of sodium lauryl sulfate and does not dissolve in olive oil, reddish-pink spots were observed in the former but not in the latter. It was suggested that when using a highly lipid-soluble detection reagent, the detection reagent can be dissolved in a less hydrophilic or non-polar solvent and used.

[0025] Table 2. Penetration of reagent solutions into flour layers TIFF0007809553000003.tif41142

Claims

1. A method for detecting chemical substances contained in cereal flour, comprising: A step of placing flour on a substrate and pressing a flat plate against the flour to form a flour layer having a flat surface; applying a reagent solution to the flat surface of the flour layer; the reagent solution comprises a detection reagent that reacts with the chemical substance to develop color or light, and a solvent, the solvent having a surface tension of 50 mN / m or less, and the detection reagent being diethyl-p-phenylenediamine; The detection method as described above, wherein the solvent is a lower alcohol selected from methanol, ethanol, 1-propanol, 2-propanol, and 1-butanol, or an aqueous solution thereof, or an aqueous solution of sodium lauryl sulfate.

2. The detection method according to claim 1, wherein the chemical substance contained in the flour is an oxidizing substance.

3. 3. The detection method according to claim 2, wherein the oxidizing substance is one or more selected from the group consisting of benzoyl peroxide, potassium bromate, sodium sulfite, and calcium hypochlorite.

4. The detection method according to any one of claims 1 to 3, wherein the cereal flour is wheat flour.

5. 5. The detection method according to claim 1, wherein the means for applying the reagent solution to the flat surface of the flour is dripping or spraying.

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