Heat denaturation preventing agent for grated yam processed food, production method for grated yam processed food, and heat denaturation preventing method for grated yam processed food

Abstract

To provide a heat denaturation preventing agent for grated yam processed food, the agent being capable of preventing simply and effectively denaturation of grated yam caused by heat treatment and having high safety properties, a production method for grated yam processed food, and a heat denaturation preventing method for grated yam processed food.SOLUTION: A heat denaturation preventing agent of grated yam processed food includes α-amylase, acidic polysaccharide, and a calcium-containing material as active ingredients, where the acidic polysaccharide is used with a ratio of 0.05-0.5 mass% relative to grated yam processed food.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a heat denaturation inhibitor for grated yam processed foods, a method for producing grated yam processed foods, and a method for preventing the heat denaturation of grated yam processed foods. [Background technology]

[0002] Yamatoimo (Japanese yam), Nagaimo (long yam), and other yams belonging to the Dioscoreaceae family are grated to produce tororo (grated yam), which has a unique viscosity and stringiness, as well as a distinctive flavor and texture. Conventionally, there have been provided cooked products using grated yam, such as grated yam soba, which is made by cooking this type of grated yam together with noodles such as soba or udon, or grated yam udon.

[0003] It is known that the viscous component of grated yam, which is made from grated yam (Japanese yam, Nagaimo, etc.) belonging to the Dioscoreaceae family, is a complex of polysaccharides (mannan polymers) and proteins (hereinafter referred to as "yam mucilage"). However, this yam mucilage is sensitive to heat, and becomes gelatinized and coagulated when heated above 65°C. For this reason, if yam is heated as is, the yam mucilage will denature, losing its characteristic stringiness and deteriorating the taste of yam.

[0004] To date, for example, a grated yam processed food has been proposed that can prevent gelatinization and coagulation due to heat treatment, even when heated together with food ingredients that are also heated and eaten.The grated yam processed food has been proposed to which α-amylase has been added so that the enzyme activity (U) per 100 g of the grated yam processed food is in the range of 400 U to 40,000 U (see, for example, Patent Document 1).

[0005] A method for producing a grated yam processed food has been proposed that prevents denaturation and deterioration due to heating of the yam mucilage, maintains stringiness and taste almost the same as that of raw grated yam immediately after grating, both during and after heat treatment, and has a reduced microbial count. The method includes a grating step in which yam belonging to the genus Dioscorea of ​​the family Dioscoreaceae is grated to produce a grated yam material, an addition step in which one or more polysaccharides selected from the group consisting of gum arabic, soybean polysaccharides, pullulan, arabinogalactan, and guar gum hydrolysate are added in an amount of 0.01 to 25% by weight of the total amount to form a grated yam additive, and a heating step in which the grated yam additive is heat-sterilized at 60°C to 125°C (see, for example, Patent Document 2). [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Patent Publication No. 2021-101693 [Patent Document 2] Japanese Patent Application Laid-Open No. 2017-153389 Summary of the Invention [Problem to be solved by the invention]

[0007] Although the above-mentioned technologies have been proposed, they are not effective enough in preventing the denaturation of grated yam due to heating. Therefore, in the case of cooked foods that use grated yam as an ingredient, such as grated yam soba and grated yam noodles, the grated yam is currently added after the heat treatment of ingredients that require heating has been completed in order to prevent denaturation due to heating.

[0008] For example, in recent years, cooked foods that use grated yam as an ingredient and are eaten after being heated, such as grated yam soba and grated yam noodles, are distributed and sold in individual containers such as small bags that are separate from the main container containing the main ingredient that requires the grated yam to be heated, in order to prevent the grated yam from being denatured by the heat treatment. When cooking a product in which an individual container containing grated yam is packaged together with a main container containing ingredients that require heat treatment, the individual container containing the grated yam is removed from the main container in advance. The ingredients stored in the main container are then cooked using a cooking appliance such as a microwave oven while still in the main container, and removed from the cooking appliance. The individual container that was previously removed from the main container is then opened, and the grated yam stored in the individual container is added to the cooked ingredients to complete the cooking process.

[0009] In the case of cooked products using grated yam as an ingredient, it is desirable to package the grated yam and the main ingredient that requires heat treatment together, taking into consideration the convenience of cooking and distribution. In addition, in consideration of the denaturation of grated yam due to heat treatment, in a cooked product in which grated yam and the main ingredients that require heat treatment are stored separately, the cooking process becomes complicated and cooking cannot be performed easily. For example, when this type of cooked product is cooked and served in a store, the work becomes complicated and it becomes difficult to provide it to customers quickly. Therefore, there is a need for a technology that can prevent the denaturation of grated yam due to heat treatment and eliminate such complicated cooking.

[0010] On the other hand, if the denaturation of grated yam due to heat can be sufficiently prevented, it will be possible for grated yam manufacturers to produce an excellent product even if they heat-sterilize the grated yam after packaging it in bags.

[0011] The present invention addresses these demands, breaks through the current situation, solves the above-mentioned conventional problems, and aims to achieve the following objectives: That is, the present invention aims to provide a highly safe thermal denaturation inhibitor for grated yam processed foods that can simply and effectively prevent denaturation of grated yam due to heat treatment, a method for producing grated yam processed foods, and a method for preventing thermal denaturation of grated yam processed foods. [Means for solving the problem]

[0012] As a result of intensive research conducted by the inventors to achieve the above-mentioned object, they discovered that by using α-amylase, acidic polysaccharides, and calcium-containing materials as active ingredients, and by using the acidic polysaccharides in an amount of 0.05 to 0.5% by mass relative to the grated yam processed food, gelatinization and coagulation of the grated yam processed food upon heating can be suppressed, and the texture and color of the original grated yam material can be maintained even after heat treatment, thereby completing the present invention.

[0013] The present invention is based on the findings of the present inventors, and the means for solving the above problems are as follows: <1> It contains α-amylase, acidic polysaccharides, and calcium-containing materials as active ingredients, The heat denaturation inhibitor for grated yam processed foods is characterized in that the acidic polysaccharide is used in an amount of 0.05 to 0.5% by mass relative to the grated yam processed food. <2> The α-amylase is 2,000 to 60,000 U per 100 g of grated yam processed food, The calcium-containing material is used in an amount of 0.05 to 2% by mass relative to the grated yam processed food. <1> The heat denaturation inhibitor for grated yam processed foods described in 1. <3> The acidic polysaccharide is one or more selected from the group consisting of carrageenan, gum arabic, and alginic acid. <1> or <2> The heat denaturation inhibitor for grated yam processed foods described in 1. <4> The calcium-containing material is at least one selected from the group consisting of calcium maltobionate, calcium acetate, calcium carbonate, and dolomite. <1> ~ <3> The heat denaturation inhibitor for grated yam processed foods is described in any one of the above. <5> The aforementioned <1> ~ <4> The method includes adding and mixing the heat denaturation inhibitor for grated yam processed foods described in any one of the above to a grated yam material before heating, This is a method for producing grated yam processed food, characterized in that the grated yam material is grated yam belonging to the Dioscoreaceae family. <6> The aforementioned <1> ~ <4> The method includes adding and mixing the heat denaturation inhibitor for grated yam processed foods described in any one of the above to a grated yam material before heating, This is a method for preventing thermal denaturation of grated yam processed food, characterized in that the grated yam material is grated yam belonging to the Dioscoreaceae family. [Effects of the Invention]

[0014] According to the present invention, the above-mentioned problems of the prior art can be solved, the above-mentioned object can be achieved, and a heat-denaturation inhibitor for grated yam processed foods, a method for producing grated yam processed foods, and a method for preventing the heat-denaturation of grated yam processed foods can be provided, which can simply and effectively prevent the denaturation of grated yam due to heat treatment and are highly safe. DETAILED DESCRIPTION OF THE INVENTION

[0015] (Heat denaturation inhibitor for grated yam processed foods) The heat-denaturation inhibitor for grated yam processed foods of the present invention (hereinafter sometimes referred to as "heat-denaturation inhibitor") contains at least α-amylase, acidic polysaccharides, and a calcium-containing material, and may further contain other ingredients as necessary.

[0016] In the present invention, α-amylase, acidic polysaccharides, and calcium-containing materials, which have been used as food additives and have a long history of use in the diet, are used as active ingredients of the heat denaturation inhibitor.

[0017] <α-amylase> The α-amylase is not particularly limited as long as it is of a food grade and can be appropriately selected, and examples thereof include α-amylases derived from microorganisms such as those of the genus Aspergillus, such as Aspergillus oryzae; those of the genus Bacillus, such as Bacillus subtilis, Bacillus amyloliquefaciens, and Bacillus licheniformis; and those of the genus Streptomyces; and α-amylases derived from grains such as barley and wheat. These may be used alone or in combination of two or more.

[0018] As the α-amylase, commercially available products can be used as appropriate.

[0019] The content of the α-amylase in the heat denaturation inhibitor is not particularly limited and can be appropriately selected depending on the amount used, activity, etc.

[0020] The amount of α-amylase used is not particularly limited and can be selected as appropriate, but is preferably in the range of 2,000 to 60,000 U ("U" represents activity units (units), hereinafter the same) per 100 g of grated yam processed food, and more preferably in the range of 3,000 to 56,000 U. If the amount used is less than 2,000 U, it may not be possible to sufficiently prevent denaturation of the grated yam processed food when heated, and if it exceeds 60,000 U, the grated yam may have poor viscosity and spinnability, which are characteristic of grated yam.

[0021] In the present invention, the activity unit of α-amylase is defined as the activity that reduces the iodine (I2) color value by 1% per minute when 1 mL of the enzyme solution is added to 10 mL of 1% potato starch paste (pH 6.0, M / 10 acetate buffer) and allowed to react at 40°C for 10 minutes.

[0022] The 1% potato starch paste liquid may be prepared, for example, as follows. Add 40 mL of water and 10 mL of 1N NaOH to 2.0 g of potato starch and stir until a paste forms. After stirring for 5 minutes in boiling water, add 50 mL of water, stir, and cool. Adjust the pH to 6 with 0.1N acetic acid, then make the volume to 200 mL to use as the substrate solution.

[0023] The iodine solution used in the measurement may be prepared, for example, as follows. Dissolve 5g of iodine and 50g of potassium iodide in water to make 500mL. Dilute this 200 times before use.

[0024] The activity of the α-amylase can be measured, for example, as follows and calculated using the following formula. Place 5 mL of the above substrate solution in a test tube and incubate at 40°C ± 0.5°C for 5 minutes. Add 0.5 mL of sample solution (0.5 mL of water for the blank), stir, and react at 40°C ± 0.5°C for 10 minutes. Add 0.5 mL of the reaction solution to 5 mL of 0.1 N HCl and mix well to stop the reaction. Add 0.5 mL of the reaction-stopped solution to 5 mL of the above iodine solution and shake. Measure the absorbance at a wavelength of 660 nm. [formula] α-amylase activity = (A0 - A t ) / A0 × sample dilution factor / mL × 100% / 10 In the above formula, "A0" is the absorbance in the blank, "A t " represents the absorbance in the sample solution.

[0025] Although it varies depending on the specific activity, the amount of α-amylase is usually in the range of 200 to 8,600 ppm, preferably 300 to 8,000 ppm, relative to the amount of grated yam processed food.

[0026] <Acidic polysaccharide> The acidic polysaccharide is not particularly limited and can be appropriately selected as long as it is of a grade suitable for food applications, and examples thereof include carrageenan, pectin, gum arabic, xanthan gum, alginic acid, gellan gum, agar, tragacanth gum, etc. These may be used alone or in combination of two or more. Among the above-mentioned acidic polysaccharides, one or more selected from the group consisting of carrageenan, gum arabic, and alginic acid are preferred from the viewpoint of the effect of preventing the heat denaturation of grated yam processed foods.

[0027] The acidic polysaccharide may be composed solely of the acidic polysaccharide, or may be an acidic polysaccharide-containing composition containing components other than the acidic polysaccharide. Examples of the acidic polysaccharide-containing composition include seaweed extract.

[0028] As the acidic polysaccharide, commercially available products can be used appropriately.

[0029] The content of the acidic polysaccharide in the heat denaturation preventing agent is not particularly limited and can be appropriately selected depending on the amount used and the like.

[0030] The amount of the acidic polysaccharide used is not particularly limited as long as it is in the range of 0.05 to 0.5% by mass relative to the amount of the grated yam processed food, and can be appropriately selected, but is preferably in the range of 0.08 to 0.3% by mass. If the amount used is less than 0.05% by mass, denaturation of the grated yam processed food when heated cannot be sufficiently prevented, and if it exceeds 0.5% by mass, the grated yam processed food will have a strong pasty texture, resulting in an undesirable texture.

[0031] <Calcium-containing materials> The calcium-containing material is a material that contains calcium ions (Ca 2+ ) and compositions containing calcium ions. The calcium-containing material is not particularly limited and can be appropriately selected as long as it is of a grade suitable for food applications. For example, calcium ions (Ca 2+ ), organic acid salts or inorganic acid salts of calcium ions, minerals containing calcium ions, yeast extracts containing calcium ions, etc. These may be used alone or in combination of two or more. Among the calcium-containing materials, one or more selected from the group consisting of calcium maltobionate, calcium acetate, calcium carbonate, and dolomite are preferred from the viewpoint of the effect of preventing thermal denaturation of grated yam processed foods.

[0032] As the calcium-containing material, commercially available products can be used as appropriate.

[0033] The content of the calcium-containing material in the heat denaturation inhibitor is not particularly limited and can be appropriately selected depending on the amount used, etc.

[0034] The amount of the calcium-containing material used is not particularly limited and can be selected appropriately, but is preferably in the range of 0.05 to 2% by mass, more preferably 0.1 to 1% by mass, of the grated yam processed food. If the amount used is less than 0.05% by mass, it may not be possible to sufficiently prevent denaturation of the grated yam processed food when heated, and if it exceeds 2% by mass, the color tone of the grated yam processed food may become undesirable and it may also have an unpleasant taste such as a harsh taste or bitterness.

[0035] The amount of calcium to be added to the grated yam processed food is not particularly limited and can be appropriately selected depending on the purpose, and can be, for example, in the range of 0.01 to 0.5% by mass.

[0036] <Other ingredients> The other components are not particularly limited as long as they do not impair the effects of the present invention and can be selected appropriately, and examples thereof include seasonings such as salt and soy sauce; sugars such as monosaccharides, disaccharides, maltotriose, oligosaccharides, dextrin, and sugar alcohols; starches; bacteriostatic agents such as glycine, egg white lysozyme, and sodium acetate; organic acids or salts thereof such as citric acid and lactic acid; emulsifiers such as glycerin fatty acid esters, organic acid monoglycerides, and polyglycerin fatty acid esters; antioxidants such as ascorbic acid, tocopherols, and tea extracts. These may be used alone or in combination of two or more.

[0037] As the other components, commercially available products can be used as appropriate.

[0038] The content of the other components in the heat-denaturation preventing agent and the amount of the other components used are not particularly limited and can be selected appropriately.

[0039] <Aspect> The heat denaturation inhibitor may be in a form in which α-amylase, acidic polysaccharides, calcium-containing material, and, if necessary, the other ingredients are contained in the same packaging material, or one or more of the ingredients may be placed in separate packaging materials and the ingredients are mixed and added to the grated yam material at the time of use, or each of the ingredients may be added separately to the grated yam material. The form of the heat-deterioration preventing agent is not particularly limited and can be selected appropriately.

[0040] <Use> The amount of the heat-deterioration inhibitor used is not particularly limited and can be appropriately selected depending on the amount of each of the above-mentioned components used.

[0041] The method of using the heat denaturation inhibitor is not particularly limited as long as it is used on the grated yam material before heating, and can be selected appropriately.

[0042] The heat denaturation inhibitor may be used alone or together with other preparations such as a shelf life improver.

[0043] The heat denaturation inhibitor can be suitably used to prevent heat denaturation when the grated yam processed food is heated to 65 to 100°C.

[0044] <Processed grated yam food> The grated yam processed food that is the target of thermal denaturation prevention in the present invention is made primarily from grated yam material (hereinafter sometimes referred to as "gray yam material") made from grated yam belonging to the genus Dioscorea of ​​the Dioscoreaceae family. The grated yam processed food may consist of grated yam ingredients alone, or may contain ingredients other than the grated yam ingredients, such as water and seasonings, as necessary.

[0045] The method for preparing the grated yam material is not particularly limited, and any known method can be appropriately selected. For example, a method can be mentioned in which the yam used as the raw material for the grated yam material is washed with water, peeled, washed, then the surface is sterilized, and the grated yam is grated using a grater or the like to prepare the grated yam material.

[0046] As the grated yam material of the present invention, any one of grated Yamatoimo, Nagaimo, and other yams belonging to the Dioscoreaceae family can be used alone, or a mixture of grated yams of these yams in an appropriate ratio can be used.

[0047] The use of the grated yam processed food is not particularly limited and can be appropriately selected depending on the purpose. For example, the grated yam processed food can be directly served on noodles such as soba noodles, placed in a container together with soup and other ingredients, and heated before eating, or the grated yam processed food can be packaged in a bag and then heat-sterilized to provide it as a bagged grated yam processed food. The bagged grated yam processed food can be eaten as is without heating, or can be heated before eating.

[0048] The heating method for the grated yam processed food is not particularly limited and can be appropriately selected depending on the application, etc. For example, methods such as hot water sterilization in a water bath, dry heat in an atmosphere, retort heating, microwave heating, etc. When heated, the grated yam processed food may be sealed in a bag or container.

[0049] The temperature and conditions for the heating are not particularly limited and can be selected appropriately.

[0050] (Method of manufacturing grated yam processed food) The method for producing grated yam processed food of the present invention includes at least an adding and mixing step, and may further include other steps as necessary.

[0051] <Addition and mixing process> The adding and mixing step is a step of adding the heat denaturation preventing agent of the present invention to the grated yam material before heating and mixing it.

[0052] -Tororo ingredients- The grated yam material is made by grating and processing Japanese yam belonging to the Dioscoreaceae family. The grated yam material is as described above in the section "Heat denaturation inhibitor for grated yam processed foods."

[0053] -Adding and mixing- In the adding and mixing step, it is preferable to add the heat denaturation preventing agent to the grated grated yam material and mix until it is uniformly dissolved. The grated yam material to be added and mixed may be grated yam on the spot, or may be grated and then packaged in a container and refrigerated or frozen. When adding and mixing, it is preferable to add it in small amounts, taking care not to mix it with other ingredients. Water may be added as needed.

[0054] The amount of water is not particularly limited and can be selected appropriately, but is preferably 50% by mass or less of the total mass of the grated yam processed food of the present invention. If water is added in an amount exceeding 50% by mass of the total mass of the grated yam processed food, the taste specific to the grated yam material, such as viscosity and stringiness, may be lost.

[0055] In the above-mentioned adding and mixing, seasonings may be added as needed.

[0056] In addition, when water or seasonings are added to the grated yam processed food, the amount of the heat denaturation inhibitor to be added is determined based on the total mass including the water and seasonings.

[0057] The amount of the heat-denaturation preventing agent of the present invention and the amount of each component of the heat-denaturation preventing agent used in the adding and mixing steps is not particularly limited and can be selected appropriately as long as it does not impair the effects of the present invention. For example, the amount can be the amount described in the above section "Heat-denaturation preventing agent for grated yam processed foods."

[0058] <Other processes> The other steps are not particularly limited and can be appropriately selected as long as they do not impair the effects of the present invention, and examples thereof include a heating step.

[0059] -Heating process- The heating step is a step of heating the grated yam processed food prepared in the adding and mixing step. The heating method is not particularly limited and can be appropriately selected depending on the purpose. For example, the same method as the "heating method for grated yam processed foods" described in the above section "Heat denaturation inhibitor for grated yam processed foods" can be used.

[0060] (Method for preventing heat denaturation of grated yam processed foods) The method for preventing thermal denaturation of grated yam processed foods of the present invention includes at least the steps of adding and mixing, and may further include other steps as necessary.

[0061] The method for preventing thermal denaturation of the grated yam processed food can be carried out in the same manner as the method for producing the grated yam processed food of the present invention described above.

[0062] The method for preventing thermal denaturation of grated yam processed foods can be suitably used as a method for preventing thermal denaturation of grated yam processed foods when heated to 65 to 100°C.

[0063] According to the heat-denaturation inhibitor for grated yam processed foods, the method for producing grated yam processed foods, and the method for preventing heat-denaturation of grated yam processed foods of the present invention, even when the food is heat-treated, including when it is heated together with ingredients that will be heat-treated and eaten, it is possible to prevent gelatinization and coagulation due to the heat treatment, and it is also possible to maintain the texture and color of the grated yam ingredients when they are first grated and processed. [Example]

[0064] The present invention will be explained below by showing test examples, but the present invention is not limited to these test examples.

[0065] The α-amylase, polysaccharides, and calcium-containing materials used in the following test examples are listed below. Note that these are used as examples of each component. α-Amylase A: α-amylase with an enzymatic activity of 100,000 U / g (Uniase BM-8, Yakult Pharmaceutical Co., Ltd.) α-Amylase B: α-Amylase with an enzymatic activity of 70,000 U / g (Clystase SD8, Amano Enzyme Co., Ltd.) Acidic polysaccharide A: Seaweed extract containing 80% alginic acid by weight Acidic polysaccharide B: Carrageenan Acidic polysaccharide C: Gellan gum Acidic polysaccharide D: xanthan gum Acidic polysaccharide E: Gum arabic Neutral polysaccharide A: Guar gum Neutral polysaccharide B: Tamarind seed gum Calcium-containing material A: Dolomite (calcium content: 22.5% by mass) Calcium-containing material B: calcium maltobionate Calcium-containing material C: calcium acetate Calcium-containing material D: calcium lactate Calcium-containing material E: calcium carbonate

[0066] (Test Example 1) <Test Examples 1-1 to 1-5> -Preparing grated yam- Each component shown in Table 1 below was added to 60 g of thawed grated yam in the amount shown in Table 1 below, and then mixed. In Table 1, "mass %" indicates the amount relative to the grated yam, and "U" indicates the enzyme activity per 100 g of grated yam (the same applies to Tables 2 to 8 below).

[0067] -evaluation- The grated yam prepared above was placed in a container and microwaved for 2 minutes at 500 W. After cooling, the grated yam was evaluated for its physical properties and color. The results are shown in Table 1.

[0068] [Gelinization prevention effect] After visually checking the appearance, the grated yam was stirred with chopsticks and rated on a scale of 1 to 5. A weakly thickened, gelatinized state was given a score of 1, and the closer the grated yam was to the texture of the grated yam before microwave heating, the higher the score.

[0069] [Color tone] The color of the grated yam was visually confirmed.

[0070] [Tackiness] The grated yam was stirred with chopsticks and rated on a scale of 1 to 5. A score of 1 was given for a texture that was weakly viscous and loose, and a higher score was given for textures that were closer to the grated yam before heating in the microwave. In addition, Test Examples 1-2 and 1-3 could not be evaluated for viscosity because they had solidified (referred to as "solidified" in Table 1).

[0071] [Table 1]

[0072] (Test Example 2) <Test Examples 2-1 to 2-3> A grated yam was prepared in the same manner as in Test Example 1, except that each component shown in Table 2 below was added in the amount shown in Table 2 below. The anti-gelatinization effect, color tone, and stickiness were also evaluated in the same manner as in Test Example 1. The results are shown in Table 2.

[0073] [Table 2]

[0074] Test Example 2-3 lacked the viscosity and stringiness characteristic of grated yam and had a watery texture. In addition, it quickly melted in the mouth and did not have the taste and texture characteristic of grated yam.

[0075] (Test Example 3) <Test Examples 3-1 to 3-6> A grated yam was prepared in the same manner as in Test Example 1, except that each component shown in Table 3 below was added in the amount shown in Table 3 below. The anti-gelatinization effect and color tone were also evaluated in the same manner as in Test Example 1. The results are shown in Table 3.

[0076] [Table 3]

[0077] (Test Example 4) <Test Examples 4-1 to 4-7> A grated yam was prepared in the same manner as in Test Example 1, except that each component shown in Table 4 below was added in the amount shown in Table 4 below. The anti-gelatinization effect and color tone were also evaluated in the same manner as in Test Example 1. The results are shown in Table 4.

[0078] [Table 4]

[0079] (Test Example 5) <Test Examples 5-1 to 5-4> A grated yam was prepared in the same manner as in Test Example 1, except that each component shown in Table 5 below was added in the amount shown in Table 5 below. The anti-gelatinization effect and color tone were also evaluated in the same manner as in Test Example 1. The results are shown in Table 5.

[0080] [Table 5]

[0081] (Test Example 6) <Test Examples 6-1 to 6-5> A grated yam was prepared in the same manner as in Test Example 1, except that each component shown in Table 6 below was added in the amount shown in Table 6 below. The anti-gelatinization effect and color tone were also evaluated in the same manner as in Test Example 1. The results are shown in Table 6.

[0082] [Table 6]

[0083] (Test Example 7) <Test Examples 7-1 to 7-7> A grated yam was prepared in the same manner as in Test Example 1, except that each component shown in Table 7 below was added in the amount shown in Table 7 below. The anti-gelatinization effect and color tone were also evaluated in the same manner as in Test Example 1. The results are shown in Table 7.

[0084] [Table 7]

[0085] (Test Example 8) <Test Examples 8-1 to 8-3> A grated yam was prepared in the same manner as in Test Example 1, except that each component shown in Table 8 below was added in the amount shown in Table 8 below. The anti-gelatinization effect and color tone were also evaluated in the same manner as in Test Example 1. The results are shown in Table 8.

[0086] [Table 8]

[0087] As described above, it has been confirmed that the present invention can simply and effectively prevent the denaturation of grated yam due to heat treatment.

Claims

1. It contains α-amylase, acidic polysaccharides, and a calcium-containing material as active ingredients, A heat denaturation inhibitor for grated yam processed foods, characterized in that the acidic polysaccharide is used in an amount of 0.05 to 0.5% by mass relative to the grated yam processed food.

2. The α-amylase is 2,000 to 60,000 U per 100 g of grated yam processed food, The heat denaturation inhibitor for grated yam processed foods according to claim 1, wherein the calcium-containing material is used in an amount of 0.05 to 2% by mass relative to the grated yam processed food.

3. The heat-denaturation inhibitor for grated yam processed foods according to claim 1 or 2, wherein the acidic polysaccharide is one or more selected from the group consisting of carrageenan, gum arabic, and alginic acid.

4. The heat-denaturation inhibitor for grated yam processed foods according to claim 1 or 2, wherein the calcium-containing material is one or more selected from the group consisting of calcium maltobionate, calcium acetate, calcium carbonate, and dolomite.

5. The method comprises adding and mixing the heat denaturation inhibitor for grated yam processed foods according to claim 1 or 2 to a grated yam material before heating, The method for producing grated yam processed food, wherein the grated yam material is grated yam belonging to the Dioscoreaceae family.

6. The method comprises adding and mixing the heat denaturation inhibitor for grated yam processed foods according to claim 1 or 2 to a grated yam material before heating, The method for preventing thermal denaturation of grated yam processed foods, wherein the grated yam material is grated yam belonging to the Dioscoreaceae family.

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