Manufacturing method for soy-based processed foods

Abstract

To provide a method for producing soy-based processed foods with an increased content of the functional ingredient γ-aminobutyric acid. [Solution] When grinding water-soaked soybeans, the amount of water added is adjusted to be less than the final target amount to produce the mullet. After keeping the resulting mullet warm for a certain period of time, additional water is added to reach the final target amount, thereby enabling the production of tofu, soy milk, and okara with a high γ-aminobutyric acid content.

Description

Technical Field

[0001] The present invention relates to a method for producing a processed soy food, which comprises adjusting the amount of water added when grinding water-absorbed soybeans to be less than the final target amount, obtaining a soy grind (hereinafter referred to as "Wu"), keeping it warm for a certain period of time, and then adding water to reach the final target amount.

Background Art

[0002] Soybeans contain γ-aminobutyric acid (hereinafter referred to as "GABA"), which is known to have physiological effects such as blood pressure lowering and mental stabilization effects. It is also contained in processed soy foods such as tofu, soy milk, and okara. However, the content of GABA is low, and its effect cannot be expected with an amount that can be ingested without difficulty in daily life.

[0003] Therefore, methods for increasing GABA in processed soy foods have been proposed. For example, in Patent Document 1, a method for producing tofu and the like, which increases GABA by making glutamate decarboxylase work by keeping "Wu" at 20 to 60°C for 2 to 12 hours, has been proposed. Also, it is known that germinated soybeans contain more GABA than soybeans, and tofu and the like with increased GABA are commercially available by using germinated soybeans.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] However, maintaining the temperature of the soybean paste at 20°C to 60°C for extended periods carries a high risk of quality deterioration due to microbial contamination and results in low production efficiency. Furthermore, prolonged heating causes lipid oxidation, leading to the development of a characteristic grassy odor of soybeans. Additionally, using germinated soybeans also results in low production efficiency, as the germination process generally takes several hours or more. Therefore, there is still room for improvement.

[0006] The present invention aims to provide a method for producing soy-based processed foods with increased GABA content through short-time processing, in order to solve the problems of the conventional technology described above. [Means for solving the problem]

[0007] To solve the above problems, the inventors of the present invention discovered that by reducing the amount of water added during the production of Kure and performing a heat retention treatment, the reaction by glutamate decarboxylase is promoted, and GABA can be increased in a shorter time than when heat retention is performed with the usual amount of water added, thus completing the present invention. [Effects of the Invention]

[0008] This invention provides a soy-based food product that allows for the intake of GABA in an amount that can be easily consumed on a daily basis and is expected to have a blood pressure-lowering effect. Furthermore, while soy-based foods such as tofu contain isoflavones that have physiological effects on maintaining bone health, most of these are glycoside-type isoflavones that are not easily absorbed into the body, and aglycone-type isoflavones, which are easily absorbed and exert their effects, are very few. This invention provides a soy-based food product that increases the amount of aglycone-type isoflavones in addition to GABA. [Brief explanation of the drawing]

[0009] [Figure 1] Figure 1 is a graph showing the change in GABA content over time when different amounts of water are kept warm. [Modes for carrying out the invention]

[0010] The present invention will be described in more detail below.

[0011] The soy-based processed foods of this invention relate to tofu, soy milk, and okara (soy pulp). While tofu can be categorized into types such as silken tofu, firm tofu, packaged tofu, and soft tofu depending on the manufacturing method, the invention is not limited to any specific type. Furthermore, the types of raw soybeans and additives are not limited to any specific type.

[0012] In the method for producing soybean processed food according to the present invention, the soybeans are soaked in a sufficient amount of water according to the method used in normal production. At room temperature, they are soaked for 6 to 20 hours depending on the season. At low temperatures of about 5°C, they are soaked for 18 to 24 hours, and at high temperatures of about 40°C, they are soaked for 3 to 6 hours.

[0013] The amount of water added during the production of soy milk paste varies depending on the type of tofu being made. For silken tofu, which requires the least amount of water, water is generally added so that the Brix of the soy milk reaches 12-13. The amount of water added at this time varies depending on the soybeans, but generally, water is added so that the total weight after grinding is 5-6 parts by weight for every 1 part by weight of soybeans. In this invention, by producing soy milk paste with less water added during grinding than this, the enzymatic reaction is promoted, and GABA is increased in a short time, thereby preventing quality deterioration due to prolonged heat retention.

[0014] The temperature in the heat retention process in this invention should be such that glutamate decarboxylase is not deactivated, and is preferably around 40-70°C. It is not necessary to maintain a constant temperature, and the temperature may be increased during heat retention. The heat retention time is not particularly limited, but it is preferably 1 hour or less to prevent the generation of a grassy odor due to lipid oxidation and to improve production efficiency.

[0015] The water added to adjust the Brix after the heat retention process may be added before the soybean mixture boils, or it may be added in a later step. If added after boiling, it is preferable to add sterilized water.

[0016] Furthermore, an enzyme agent may be added to the soybeans as needed. For example, by adding β-glucosidase, the content of aglycone-type isoflavones can be further increased.

[0017] Furthermore, the processed soybean food obtained by the present invention can also be used as a raw material for another processed food.

Examples

[0018] Next, examples of the present invention are shown below, but these do not limit the scope of the present invention.

[0019] <Method for Measuring GABA> GABA was extracted by adding 2% sulfosalicylic acid to the sample and measured using an amino acid automatic analyzer "L-8900" (Hitachi High-Technologies).

[0020] <Method for Measuring Isoflavones> Isoflavones were extracted by adding 70% ethanol to the sample and measured in accordance with "Guidelines for Handling Specific Health Foods Containing Soybean Isoflavones, etc." No. 0823001 issued by the Ministry of Health, Labour and Welfare on August 23, 2006.

[0021] <Test Example 1> After washing 1 part by weight of soybeans with water, 3 parts by weight of water were added, and the mixture was immersed at 10°C for 20 hours. The water-absorbed soybeans were ground while adding water to obtain okara with a total weight of 3, 4, or 5 parts by weight. After keeping these okara at 45°C for 60 minutes, 3, 2, or 1 part by weight of water was added to make the total weight 6 parts by weight, and then heated at 97°C for 3 minutes. Then, the okara was squeezed to obtain soy milk with 13°Brix and okara (Examples 1, 2, and 3). As a comparative example, okara with a total weight of 6 parts by weight after grinding was kept at 45°C for 60 minutes, heated at 97°C for 3 minutes, and then the okara was squeezed to obtain soy milk with 13°Brix and okara (Comparative Example 1). Also, as a conventional production method, okara with a total weight of 6 parts by weight was heated at 97°C for 3 minutes, and then the okara was squeezed to obtain soy milk with 13°Brix and okara (Comparative Example 2). Regarding Example 2 and Comparative Example 1, soy milk with 13°Brix was also obtained in the same manner from okara with holding times of 30, 90, and 120 minutes.

[0022] The results of Test Example  1 are shown in Table 1 and Figure 1. As shown in Table 1, by adding a holding step before heating the okara at 97°C for 3 minutes, the GABA in soy milk and okara could be increased. Also, by reducing the amount of water added during grinding to less than about 6 parts by weight, which is the conventional production method, the increase rate of GABA could be further increased even under the same holding conditions, enabling the production of GABA-rich soy processed foods by short-time treatment. Furthermore, the amount of aglycone-type isoflavones could also be increased at the same time. Also, as shown in Figure 1, by reducing the amount of water added and holding, it became possible to shorten the holding time to about half until the same amount of GABA was produced.

[0023]

Table 1

[0024] <Test Example 2> After washing 1 part by weight of soybeans with water, 3 parts by weight of water were added and the soybeans were soaked at 10°C for 20 hours. The soybeans after soaking were ground while adding water to obtain a total weight of 4 parts by weight of soybean paste. This paste was kept warm for 15 minutes at 70°C (Example 4), 60°C (Example 5), 50°C (Example 6), and 40°C (Example 7). 2 parts by weight of water was added to each paste to bring the total weight to 6 parts by weight, and the paste was heated at 97°C for 3 minutes. The paste was then squeezed to obtain soy milk and okara with a Brix of 13 degrees. In addition, a paste with a total weight of 5 parts by weight after grinding was kept warm at 60°C for 15 minutes. 1 part by weight of water was added to bring the total weight to 6 parts by weight, and the paste was heated at 97°C for 3 minutes. The paste was then squeezed to obtain soy milk and okara with a Brix of 13 degrees (Example 8). As a comparative example, paste with a total weight of 6 parts by weight was obtained using different amounts of water added during grinding. This soybean paste was kept warm at 70°C (Comparative Example 3), 60°C (Comparative Example 4), 50°C (Comparative Example 5), and 40°C (Comparative Example 6) for 15 minutes, then heated at 97°C for 3 minutes, and the paste was squeezed to obtain soy milk and okara with a Brix of 13 degrees. In addition, as a conventional manufacturing method, 6 parts by weight of soybean paste was heated at 97°C for 3 minutes, and the paste was squeezed to obtain soy milk and okara with a Brix of 13 degrees (Comparative Example 7). Furthermore, 0.005 parts by weight of calcium sulfate was added to 1 part by weight of the soy milk obtained in Example 5 and Comparative Example 7, and it was kept warm at 70°C for 30 minutes to coagulate, thereby obtaining silken tofu.

[0025] The results of Test Example 2 are shown in Tables 2 and 3. As shown in Tables 2 and 3, at all incubation temperatures, a smaller amount of added water resulted in a greater increase in GABA.

[0026] [Table 2]

[0027] [Table 3]

[0028] Furthermore, sensory evaluations of the tofu from Example 5 and Comparative Example 7 were conducted by a panel of eight people. The results showed no difference in grassy odor, indicating that we were able to produce sensory-quality tofu. [Industrial applicability]

[0029] This invention makes it possible to produce soy-based processed foods with increased GABA content in a short processing time. Simultaneously, it also makes it possible to produce soy-based processed foods with a higher proportion of aglycone-type isoflavones.

Claims

1. A method for producing soybean processed food, characterized by adjusting the amount of water added when grinding water-soaked soybeans to be less than the final target amount, keeping the resulting mixture warm for a certain period of time, and then adding water to reach the final target amount.

2. A method for producing a soybean processed food, characterized in that the amount of water added when grinding the water-soaked soybeans is at least 1 part by weight less than the final target amount of raw soybeans.

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