JP2007228928A - Method for producing soymilk - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for easily producing soymilk which contains a large amount of GABA and has excellent flavor, at a low cost without affecting soymilk quality. <P>SOLUTION: This method for producing the soymilk comprises a liquidizing process of obtaining mixed liquid of a soybean crushed matter and water, or solution obtained by removing water insoluble component from the mixed liquid, a pH decreasing process of decreasing pH of the mixed liquid or the solution to the vicinity of optimum pH of glutamic acid decarboxylase, a holding process of holding the mixed liquid or the solution for a fixed time in a condition of producing no precipitation therein while retaining the decreased pH at the vicinity of the optimum pH, and a pH increasing process of increasing the decreased pH to prescribed pH after the holding process. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a method for producing soymilk, and more particularly to a method for producing soymilk that contains a large amount of γ-aminobutyric acid and has a good flavor.

  Soymilk has been used as a raw material for tofu and yuba since ancient times. Soymilk is rich in plant protein and not only has inferior nutritional value compared to milk, but also recently found to be effective against lifestyle-related diseases, so it is now drunk as a functional food It is also offered to.

  Γ-Aminobutyric acid (GABA), which is a kind of component contained in soy milk, is a kind of physiologically active amino acid that acts as a neurotransmitter in the vertebrate brain and the like. The effect on health is drawing attention. That is, GABA has various effects such as an inhibitory effect on blood pressure increase, an effect of promoting cerebral metabolism, an effect of improving various symptoms of cerebrovascular disorder, an effect of improving various symptoms associated with head injury, an effect of improving muscle atrophy disease, and an effect of improving diabetes. It has been confirmed that there is no problem in terms of safety even when ingested from food. For this reason, expectations for treatment and prevention effects on various diseases, particularly hypertension and diabetes, which are closely related to lifestyle-related diseases, have increased, and measures for daily intake of GABA have been widely studied.

In vivo, GABA is produced by glutamate decarboxylase (GAD) acting on glutamic acid (Glu), which is a kind of amino acid, and the α-carboxyl group of glutamic acid is eliminated. It has been found that glutamate decarboxylase is widely found in higher animal brain tissues as well as in higher plants. Glutamate decarboxylase is required as a coenzyme, pyridoxal acid (PLP) is a coenzyme-type vitamin B _6. In immature soybean seeds, the optimum pH of glutamate decarboxylase is around 5.8, and it is known that the activity is further increased under stress conditions in a low oxygen state (Non-patent Document 1). .

  As a method for producing a food material containing a large amount of GABA, a method is known in which a predetermined amount of glutamic acid is added to a pumpkin pulverized solution, and this is converted to GABA with glutamate decarboxylase contained in the pumpkin pulverized solution (patent) Reference 1). However, in this production method, it is necessary to supply glutamic acid from the outside, and in order to prevent the pH from falling below the optimum pH of glutamic acid decarboxylase, glutamic acid is divided into several times. Must be added. For this reason, in order to manufacture such a food material, it has resulted in a great deal of effort.

  Patent Document 2 discloses a method of adding a large amount of carbon dioxide to soy milk in order to mask the bitter taste of soy milk. According to this method, soy protein is precipitated due to a decrease in pH caused by the addition of a predetermined amount of carbon dioxide. In order to prevent this, it has been necessary to raise the pH in advance.

Furthermore, as described in Patent Document 3, soy protein contained in soy milk causes precipitation below the isoelectric point, so that it is extremely difficult to produce a stable acidic soy milk drink. Therefore, for example, in order to produce soy milk containing a large amount of GABA, soy protein will precipitate even if the pH is lowered to the optimum pH of glutamic acid decarboxylase, so that stable soy milk is made. I could not.
Barry J.M. S. Craig S. W, et al. , Gaba shunt in developing soy seeds is associated with hypoxia. Physiologia Plantarum 94, p. 219-p. 228 (1995) JP 2001-252091 A JP-A-62-166852 JP 58-183060 A

  As described above, GABA is an excellent physiologically active substance. However, since the GABA content in the food is relatively small, GABA is sufficiently ingested from the food so as to sufficiently exert an effect such as an antihypertensive action. For this purpose, a large amount of food containing GABA had to be consumed. Although foods containing a relatively large amount of GABA have been developed using the characteristics of glutamic acid decarboxylase, the quality of the food is hardly affected in the process of producing these foods. Furthermore, in order to manufacture these foods, many processes were required.

  For example, in the invention described in Patent Document 1, a food material containing a large amount of GABA can be produced by adding glutamic acid to a pumpkin pulverized solution. However, by adding a pumpkin pulverized solution to soy milk, This may not be applicable to the production of soy milk.

  Also, for the invention described in Patent Document 2, a method of masking the bitter taste of soy milk by adding carbon dioxide is disclosed, but the purpose of adding carbon dioxide is not to adjust the pH of soy milk, In this invention, since the pH of soy milk is not lowered to a pH at which precipitation occurs when left for a long time, the invention described in Reference 2 adjusts the activity of glutamate decarboxylase to increase the amount of GABA. Not for adjusting soymilk containing.

  Therefore, it is desired to develop a production method for producing a food containing a large amount of GABA at a relatively easy and low cost without affecting the quality of the food. Development of a production method for producing a soy milk has been desired.

  The present invention has been made in view of the problems as described above, and does not affect the quality of soy milk, and easily and at low cost, producing a soy milk having a good taste and containing a large amount of GABA. The purpose is to provide.

  The present inventors lowered the pH of a mixed solution of soybean ground material and water, or a solution obtained by removing water-insoluble components from this mixed solution to a certain value or less, and retained this, and further maintained the pH constant. It was found that the GABA content in the produced soy milk can be increased without affecting the quality of the soy milk by raising the value to a value equal to or higher than the value of the soy milk, and the present invention has been completed. Specifically, an object of the present invention is to provide the following production method.

  (1) A liquefaction step for obtaining a mixed solution of soybean pulverized product and water, or a solution obtained by removing water-insoluble components from the mixed solution; and the pH of the mixed solution or the solution, the mixed solution or the solution A pH lowering step for lowering the glutamic acid decarboxylase to near the optimum pH, and maintaining the lowered pH in the vicinity of the optimum pH, and constant under conditions where precipitation does not occur in the mixed solution or the solution A method for producing soymilk, comprising: a holding step for holding time; and a pH raising step for raising the lowered pH to a predetermined pH after the holding step.

  According to the invention of (1), the pH of the mixed solution or solution obtained by the liquefaction step is reduced to near the optimum pH of glutamate decarboxylase in the mixed solution or solution by the pH lowering step and retained. Since the pH is maintained by the process, the mixed solution or solution can be held while the activity of glutamate decarboxylase is high. Thereby, since glutamic acid decarboxylase converts glutamic acid into GABA, soy milk containing a large amount of GABA can be obtained. Furthermore, after a certain time has passed in the holding step, the pH is raised to a predetermined pH in the pH raising step, so that the pH of the mixed solution or solution is maintained at a pH that causes precipitation when held for a long time. Thus, it is possible to prevent the soy protein from precipitating and to prevent the quality of the soy milk from deteriorating.

  Here, “reducing to near the optimum pH” may be a step of lowering the pH of soy milk toward the optimum pH, and in particular, to a pH at which glutamate decarboxylase exhibits activity effectively. To adjust the pH until.

  Further, “maintaining near the optimum pH” means that the pH does not always need to be constant in the holding step, and the pH may be varied within a predetermined range. That is, there may be an increase or decrease or a gradual increase in pH during the holding time.

  Furthermore, in the present invention, the “conditions for which precipitation does not occur” refers to conditions under which soy protein does not precipitate, and is a pH at which precipitation occurs when held for a long time (for example, 24 hours or longer). It means a pH at which soy protein does not precipitate during the holding time in the holding step, and a temperature that is set corresponding to this pH so that the soy protein does not precipitate during the holding time in the holding step. The “certain time” refers to a shorter time when soy protein starts to precipitate at a predetermined soymilk pH and temperature, and is sufficient time for glutamate decarboxylase to catalyze the GABA production reaction. . That is, within the above range, the combination of pH, temperature, and time in the holding step can be set as appropriate.

  The “holding step” in the present invention refers to holding in the state of a mixed solution of pulverized soybean and water, or holding in the state of a solution obtained by removing water-insoluble components from the mixed solution, or mixing It may be any of holding both the liquid and the solution in combination.

  (2) In the pH reduction step, the pH is lowered to a range of 5.6 or more and 6.1 or less, and in the holding step, the lowered pH is maintained at 5.6 or more and 6.1 or less. ) The soymilk production method.

  The optimum pH of glutamate decarboxylase is around pH 5.8. According to the invention of (2), in the pH lowering step, the pH can be lowered to near the optimum pH of glutamic acid decarboxylase in the mixed solution or solution, and the lowered pH can be maintained in the holding step. The activity of decarboxylase can be kept high, and soy milk containing a large amount of GABA can be produced.

  (3) The method for producing soymilk according to (1) or (2), wherein the holding time in the holding step is 30 minutes to 240 minutes.

  According to the invention of (3), since the holding time in the holding step is 30 minutes or more, a sufficient reaction time for converting glutamic acid into GABA can be secured. Furthermore, since the holding time in the holding step is 240 minutes or less, the pH of the mixed solution or solution is maintained for a long time so that precipitation occurs when left for a long time, thereby preventing the soy protein from being precipitated. be able to.

  (4) The method for producing soymilk according to any one of (1) to (3), wherein in the pH raising step, the pH is raised to 6.4 or more.

  It is known that soy protein in a mixed solution or solution is precipitated by maintaining the mixed solution or solution at pH 6.2 or lower for a long time. According to the invention of (4), in the pH raising step, the pH of the mixed solution or solution can be raised to pH 6.2 or higher, so that the pH of the mixed solution or solution is kept lower than pH 6.2 for a long time. By being maintained, it is possible to prevent the soy protein from being precipitated.

  (5) The method for producing soymilk according to any one of (1) to (4), wherein in the pH reduction step, the pH is lowered by dissolving carbon dioxide in the mixed solution or the solution.

  According to the invention of (5), since the pH can be lowered using carbon dioxide, the pH can be lowered easily and at low cost without impairing the flavor of soy milk. Furthermore, since carbon dioxide is easily degassed from the mixed solution or solution by decompression or heating, the pH raising step can be easily performed.

  (6) The method for producing soymilk according to (5), wherein in the pH raising step, the mixed liquid or the solution is heated to degas dissolved carbon dioxide to raise the pH.

  According to the invention of (6), the carbon dioxide dissolved in the mixed solution or solution can be degassed by heating and the pH can be raised, so that the pH raising step can be carried out without impairing the flavor of soy milk. It can be done easily. Furthermore, in the soymilk production method, heat treatment is usually performed for the purpose of inactivation of lipoxygenase, denaturation of trypsin inhibitor, sterilization, etc., but the pH raising step and heat treatment can be performed simultaneously, so that the soymilk can be efficiently produced. Can be manufactured.

  (7) The method for producing soymilk according to any one of (1) to (6), including an adding step of adding pyridoxalphosphoric acid before the holding step.

  It is known that pyridoxal phosphate is a coenzyme for glutamate decarboxylase, and adding pyridoxal phosphate increases the activity of glutamate decarboxylase. According to the invention of (7), since the activity of glutamate decarboxylase can be kept high in the holding step, glutamate can be efficiently converted to GABA.

  According to the method for producing soymilk according to the present invention, it is possible to easily produce soymilk with a good taste containing a large amount of GABA at low cost without affecting the quality of soymilk.

  Hereinafter, embodiments of the present invention will be described in detail.

<Soy milk production method>
The soymilk producing method according to the present embodiment is a mixed solution of soybean pulverized product and water (hereinafter sometimes simply referred to as “mixed solution”) or a solution obtained by removing water-insoluble components from the mixed solution (hereinafter simply referred to as “mixed solution”). A liquefaction step for producing a “solution”), a pH reduction step for reducing the pH of the mixed solution or solution to a certain value or less, and a pH of the mixture or solution reduced in the pH reduction step Is maintained for a certain period of time at a predetermined temperature, and a pH increasing step for increasing the pH of the mixed solution or solution from the lowered pH to a certain value or more.

[soy]
Any soybean can be used as the soybean used in the present invention. For example, domestic soybean, US soybean such as IOM, genetically modified soybean, or genetically non-recombinant soybean can be used.

[Manufacture of germinated soybeans]
In the present invention, it is possible to produce a mixed solution of soybean pulverized product and water in the liquefaction step or a solution in which water-insoluble components are separated from the mixed solution without any treatment being applied to the soybean. From the viewpoint of producing a mixed solution or solution containing GABA, germinated soybeans are preferably used.

(Sprouted soybean)
Germinated soy beans are soaked in water, etc. so that the soybeans containing water necessary for the germination reaction are contacted with air or oxygen after draining or during the soaking process, and the germination reaction is promoted while maintaining temperature and humidity. It means soy bean, whether or not it has actually germinated. Specifically, for example, drained soybeans are transferred to a germination bed and sprayed intermittently or wrapped with a damp cloth to advance the germination reaction. In addition, as a germination apparatus used for this invention, although the germination bed generally used can be used, it is not limited to this.

  Although it does not specifically limit as a concrete germination method, For example, it is 25-45 degreeC, More preferably, it is 25-35 degreeC, Preferably it is left for 24 to 72 hours, More preferably, it is left for 24 to 36 hours. A method is mentioned.

  Further, it is immersed in water or warm water of 10 to 45 ° C, preferably 20 to 45 ° C, more preferably 30 to 42 ° C for 0.5 to 36 hours, preferably 1 to 10 hours, more preferably 1 to 5 hours. In addition, a method of performing a gas contact step in which soybean is exposed to air or oxygen for 19 to 36 hours, preferably 20 to 30 hours, more preferably 20 to 24 hours may be mentioned during or after the soaking step. In addition, as a method of performing a gas contact process in this immersion process, the method of putting oxygen in immersion water and performing bubbling etc. are mentioned.

  As such germinated soybeans, for example, those described in WO2005 / 004633 International Publication Pamphlet can be preferably used.

[Liquefaction process]
A liquefaction process will not be specifically limited if it is a process which can obtain the liquid mixture or solution mentioned later. For example, a water-insoluble component from a mixed solution of a water-absorbing step for absorbing water into soybeans, a pulverizing step for adding water to the soaked soybeans and pulverizing the soybeans, and a pulverized soybean and water obtained as necessary Separating step. In the liquefaction step, dried soybean powder may be powdered and dissolved in water to obtain a mixed solution or solution. In the case of germinated soybeans, the water absorption step may be omitted if the germinated soybeans contain sufficient water.

(Water absorption process)
The water absorption process is not particularly limited as long as it is a process that can sufficiently soften soybeans in order to facilitate the pulverization process. The water absorption step can be appropriately adjusted by a conventional method. The water used in the water absorption step is not particularly limited, such as tap water and groundwater. However, it is preferable to use water containing only a small amount of metal ions, such as soft water, from the viewpoint of preventing precipitation of soy protein contained in soy milk.

(Crushing process)
The pulverization process is not particularly limited as long as it is a process that can be mixed liquid. The pulverization step can be appropriately adjusted by a conventional method. It does not specifically limit as a grinding | pulverization apparatus used for a grinding | pulverization process, For example, a mixer and a die may be sufficient. The water to be charged into the pulverizing apparatus in the pulverization process is not particularly limited, such as tap water and groundwater, but water containing only a small amount of metal ions such as soft water is used from the viewpoint of preventing precipitation of soy protein contained in soy milk. It is preferable.

(Separation process)
In the separation step, a water-insoluble component (for example, okara) is separated from the mixture of soybean pulverized material and water by a separation device to obtain a solution in which the water-insoluble component is separated from the mixture. As a separation apparatus used for a separation process, a screw press and a screw decanter can be used, for example.

  In the present embodiment, the “mixed liquid of soybean pulverized product and water” is a mixture of water that is obtained by finely dividing soybean by means of pulverization or grinding. If so, the production method is not particularly limited. For example, the soybean can be produced by grinding while adding water. These are sometimes called Kure or Nama Kure. The density | concentration of the ground material in a liquid mixture will not be specifically limited if soymilk can be manufactured.

  The “solution obtained by separating a water-insoluble component from the mixed solution” refers to a solution obtained by removing okara from the mixed solution by a general process for separating so-called okara. Therefore, the water-insoluble component is sometimes called okara. Moreover, a solution may be called the soymilk part obtained by the general process of isolate | separating what is called okara. This solution is obtained by removing water-insoluble components, but may contain a small amount of water-insoluble components without being removed. Therefore, in the present invention, the content of the water-insoluble component in the solution is not limited, and refers to a solution in which the water-insoluble component has been separated.

  In addition, the mixed solution or the solution may be subjected to a treatment for making the water-insoluble component finer with a stirrer or the like in order to improve the poor feeling over the throat due to the presence of the water-insoluble component. What performed the said process to the said liquid mixture may be called whole grain soymilk, and this is handled as a kind of said liquid mixture.

[PH lowering step]
In the pH lowering step, for example, carbon dioxide is blown into a mixed solution of soybean pulverized product and water, or a solution obtained by separating water-insoluble components from the mixed solution, whereby a mixed solution of soybean pulverized product and water, Alternatively, the pH of the solution obtained by separating the water-insoluble component from the mixed solution is lowered. The pH value to be lowered is preferably around pH 5.8 which is the optimum pH of glutamate decarboxylase in the mixed solution or solution, specifically, it is preferably pH 5.6 to pH 6.1. More preferably, the pH is from 5.8 to 6.0. A pH of 5.6 or higher is preferable because the soy protein in the mixed solution or solution does not precipitate in a short time in the normal temperature range.

  In the pH lowering step, a conventionally known method can be used as the method of blowing carbon dioxide into a mixed solution of pulverized soybean and water or a solution obtained by separating a water-insoluble component from the mixed solution, and is not particularly limited. The blowing method is not particularly limited as long as the pH can be lowered within the above range.

  In the above description, gaseous carbon dioxide is blown into the mixed solution or solution in order to lower the pH in the pH lowering step, but the present invention is not limited to this. That is, in order to lower the pH, dry ice may be added to the mixed solution or solution. Further, carbon dioxide in a supercritical or subcritical state may be used. These steps may be performed under pressure.

  Furthermore, in the pH lowering step of the present invention, as a method for lowering the pH, an acid such as an organic acid may be added in addition to the above carbon dioxide. Examples of organic acids include, but are not limited to, citric acid and malic acid.

[Holding process]
In the holding step, the pH of the mixed solution of soybean ground and water reduced in the pH lowering step or the solution obtained by separating the water-insoluble component from the mixed solution is preferably from 30 minutes at 10 to 40 ° C. Maintain pH 5.6 to pH 6.1 for 240 minutes. In the holding step, glutamic acid contained in the mixed solution or solution is converted to GABA by glutamic acid decarboxylase. For this reason, before the holding step, heat treatment that deactivates the enzyme cannot be performed.

  If the temperature at which the mixed solution or solution is maintained is 10 ° C. or higher, it takes time, but glutamic acid decarboxylase can sufficiently exhibit activity, which is preferable. Moreover, if it is 40 degrees C or less, the deactivation of glutamate decarboxylase and the fall of activity can be prevented. Furthermore, if the time for maintaining the pH of the mixed solution or solution in the holding step is 30 minutes or more, a sufficient amount of glutamic acid can be converted to a sufficient amount of GABA. And if it is 240 minutes or less, precipitation of soybean protein by maintaining pH of a liquid mixture or a solution to pH 6.2 or less which is a pH which precipitates when it hold | maintains for a long time can be prevented.

  That is, according to the holding step in the present invention, glutamate decarboxylase can sufficiently act without precipitating soy protein, and soy milk containing a large amount of GABA is produced without affecting the quality of soy milk. be able to.

  This holding step may be any holding step for a predetermined time at a predetermined temperature, and does not mean only a stationary state. For example, if the temperature is maintained at a predetermined temperature, processes such as pulverization, stirring, and homogenization may be included in the holding process. The holding step may be performed in a sealed container capable of keeping the temperature constant, and may be a container filled with carbon dioxide in order to prevent degassing of carbon dioxide, but is not limited thereto. Furthermore, the holding device measures the pH of the mixed solution or solution at regular time intervals, and if the pH value is higher than a predetermined value, it may further adjust the pH by adding carbon dioxide. Good.

  Note that the holding step is not limited to holding the mixed solution or solution in one holding step. For example, the holding step may be a crushing device, a separation device, or the like having a heat insulating and sealing function. Therefore, the holding time in the present invention is the time for holding in the state of a mixed solution of soybean ground material and water, the time for holding in the state of a solution in which a water-insoluble component is separated from the mixed solution, or the mixed solution and It may be any time for holding in both of the states with the solution.

[PH raising step]
In the pH raising step, the pH of the mixed solution or solution is raised to 6.4 or higher by degassing dissolved carbon dioxide from the mixed solution or solution whose pH has been lowered in the pH lowering step. In order to degas carbon dioxide dissolved from the mixed solution or solution, for example, decompression and heating can be performed. When the mixed liquid or solution is heated to degas the dissolved carbon dioxide, the heating can be performed simultaneously with other treatments such as sterilization treatment and enzyme deactivation treatment. In this embodiment, neutralization or the like is not performed in the pH raising step, so that a salt after neutralization does not occur and the flavor of soy milk is not affected. For this reason, soy milk with good flavor can be produced. Since unsterilized soymilk before holding is generally around pH 6.4, the process of “raising the pH to 6.4 or higher” is a process of returning the lowered pH to the original level. You can also.

  In the present embodiment, carbon dioxide is removed from the mixed solution or solution by reducing the pressure and heating the mixed solution of pulverized soybean and water or a solution obtained by separating the water-insoluble component from the mixed solution. Although the pH is increased, the present invention is not limited to this. That is, in the pH raising step, the pH may be raised by adding a base such as dipotassium hydrogen phosphate or disodium hydrogen phosphate.

[Enzyme deactivation treatment]
After the pH raising step, if necessary, enzyme deactivation treatment is performed by heating to deactivate the enzyme activity and stop the reduction of glutamic acid so that the umami of soy milk does not deteriorate. In soy milk, enzyme deactivation treatment is usually carried out in order to stop the occurrence of unfavorable flavor and savory taste unique to soybeans caused by enzyme activity. This enzyme deactivation treatment may be performed, for example, by heating at 75 to 100 ° C. for 2 to 15 minutes. Thereafter, heat sterilization is performed by a conventional method as necessary. In addition, you may perform an enzyme deactivation process and heat sterilization simultaneously with a direct steam blowing type instantaneous heating apparatus. In this case, for example, heat treatment may be performed at 145 ° C. for about 5 seconds. Moreover, in order to make it easy to drink before heat-sterilization, you may adjust the taste of soy milk by adding sugar, a fruit juice, etc.

  In the present invention, when oxygen dioxide degassing by heating is used in the above-described pH raising step, the pH raising step and the enzyme deactivation treatment can be performed simultaneously, and the production process is further shortened and simplified. It is preferable because it is possible.

[Addition process]
In addition, in this invention, you may perform the addition process which adds a pyridoxal phosphoric acid at the time of manufacture of soymilk. In the addition step, pyridoxal phosphoric acid is added to the mixed solution or solution before the aforementioned holding step. The pyridoxal phosphate is preferably added in an amount of 1 × 10 ⁻³ to 1 × 10 ⁻⁸ parts by weight per 1 part by weight of the dried soybean. The adding step can be performed at any stage after the grinding step and before the holding step. As the pyridoxal phosphate added in the addition step, commercially available products can be obtained and used. Examples of such commercially available products include “pyridoxal-5′-phosphate” (manufactured by Sigma). . Moreover, the extract of the foodstuff containing this can be used as an alternative to pyridoxal phosphate. For example, rice bran extract (for example, refer to JP-A-2004-147560) can be mentioned.

  The soy milk referred to in the present application is not limited to the JAS standard as well as those included in the JAS standard, and refers to all soybeans made from soybeans as a raw material. For example, what does not separate okara and what dried soybeans, made powder once, and dissolved the powder in water are also included.

(Food using soy milk)
The soy milk according to the present invention is subjected to any processing of saccharide composition, homogenization, concentration, dehydration, drying, and powdering, and further, if necessary, freezing, heating, dilution, molding, compression, steaming, fermentation, etc. It is possible to use a further processed product by performing the processing.

  The processing as described above can be performed according to a method usually used in the production of general processed foods. For example, regarding the soy milk according to the present invention, there are saccharides and other ingredients such as acidulant, seasoning, sweetener, colorant, flavoring agent, strengthening agent, preservative, antioxidant, emulsifier, quality improvement. General food additives such as additives, bases, excipients, etc., are mixed appropriately according to the purpose to obtain a liquid whose taste is adjusted, or the soy milk is concentrated, and if necessary, carbohydrates, excipients It can be advantageously carried out by blending a base or the like into a paste, or by further drying and pulverizing to form a powder.

  Since the food using the soymilk of the present invention contains almost all the components of the soymilk, the same effect is exhibited. For example, tofu and tofu pudding. Moreover, if the said soymilk contains the quantity which can exhibit the effect in another foodstuff, naturally the same effect will be exhibited. For example, noodles such as bread, pizza, udon, soba and somen, dairy products such as ice cream, pudding, and yogurt, beans such as cookies, biscuits, rice crackers, rice crackers, arare, pudding, Japanese confectionery, etc. Can also be used for foods that do not.

<Test 1: Unsterilized soymilk pH and soy protein precipitation>
200 g of commercially available domestic dried soybean (variety name: Ryuhou) was immersed in 800 ml of water at 40 ° C. for 2 hours, then taken out of the water, transferred to another container, 22 hours, and 25 minutes in water at 25 ° C. for 10 minutes. Germination was promoted in the air while being immersed, and about 440 g of germinated soybeans were obtained. Next, to about 440 g of the germinated soybeans obtained, 800 g of water at 25 ° C. was added to obtain a liquid that was extracted using a soybean milk squeezing machine (manufactured by Tokyo Unicom Co., Ltd.). A 70-mesh filter was passed through to remove slightly remaining okara to obtain unsterilized soy milk. Thereafter, unsterilized soymilk was held for 120 minutes while blowing carbon dioxide for 1 minute every 30 minutes at 30 ° C. After holding, unsterilized soymilk that had not been heat-treated at all, and after holding, the heated pasteurized soymilk was taken into a transparent test tube, and the state of precipitation that occurred after standing at room temperature for 1 day was observed.

  It is known that soymilk aggregates proteins and precipitates at about pH 6 or less. Holding for 120 minutes while blowing carbon dioxide lowered the pH to 5.95, but increased to pH 6.60 by heating. If unsterilized soymilk that has not been heat-treated at all is left for 1 day after holding, the soymilk is precipitated and separated, but after holding, the heated pasteurized soymilk is not precipitated even if it is left in the same manner. . Therefore, it was suggested that the recovery of pH by heating is effective for stably storing soy milk.

<Test 2: pH of unsterilized soymilk and precipitation of soy protein>
Unsterilized soymilk was obtained in the same manner as in Example 1. To about 400 g of this unsterilized soymilk, 3% (w / v) citric acid was added to lower the pH to 6.0 and 5.5. This was left at 20 ° C., 30 ° C. and 40 ° C., and the presence or absence of precipitation was observed every 1 hour until 7 hours later, and then whether or not precipitation was formed after 23 hours was observed.

  Table 1 shows the time at which precipitation was confirmed at each pH and each temperature. From Table 1, it was found that precipitation was confirmed within 1 hour at all temperatures at pH 5.5, and precipitation was confirmed by 23 hours at the latest even at pH 6.0.

<Test 3: pH of unsterilized soymilk and precipitation of soy protein>
Unsterilized soymilk was obtained in the same manner as in Example 1. 3% (w / v) citric acid was added to about 400 g of this unsterilized soymilk, and the pH was adjusted to 5.8. This was dispensed into a medium bottle and the pH was measured every hour while maintaining at 30 ° C. If the pH had increased, the pH was again adjusted to 5.8 with 3% (w / v) citric acid.

  Table 2 shows the change in pH of unsterilized soymilk adjusted to pH 5.8. The pH was adjusted at every measurement. Precipitation was observed 6 hours after pH adjustment. From the above results, it was found that when the pH was maintained at 5.8 to 5.9, no precipitation occurred until at least 4 hours.

<Test 4: Difference in GABA amount in soymilk with and without carbon dioxide blowing>
Unsterilized soymilk was obtained in the same manner as in Example 1. Then, soy milk was held for 120 minutes (sample A) and 180 minutes (sample B) while blowing carbon dioxide every 30 minutes at 30 ° C. As a comparative example, unsterilized soymilk not blown with carbon dioxide was held at 30 ° C. for 120 minutes (sample C) and 180 minutes (sample D). Thereafter, each unsterilized soy milk was transferred to a pan, heated at about 75 ° C. for about 15 minutes, allowed to stand at room temperature for 5 minutes, and then allowed to cool down, and then stored in a refrigerator to obtain germinated soy milk.

(Analytical method of γ-aminobutyric acid)
After 3 ml of each of germinated soymilk samples A to D and 3 ml of 5% trichloracetic acid were mixed and stirred to remove proteins by centrifugation, the supernatant was filtered using a 0.2 μm filter. About the filtrate of each sample, the content of GABA was measured using the Hitachi high-speed amino acid analyzer "L-8800A" (made by Hitachi, Ltd.).

  Table 3 shows the amount of GABA contained in Sample A to Sample D, and the pH value immediately after production, after holding, and after heating. From the above results, it was confirmed that more GABA was produced when carbon dioxide was blown during the holding time (sample A, sample B) and when carbon dioxide was not blown (sample C, sample D). From these results, the amount of GABA increased from the comparative example by blowing carbon dioxide because the pH was lowered by blowing carbon dioxide, approaching the optimum pH of glutamate decarboxylase in soy milk, and glutamate decarboxylase worked more. It was speculated that this was because an easy environment was created.

<Test 5: Soymilk using citrate buffer>
Non-sterilized soymilk was obtained by the same method as in Example 1 except that 800 g of water added when producing soymilk was replaced with 800 g of 10 mM citrate buffer (pH 5.0). Thereafter, the sample was held at 30 ° C. for 120 minutes and 180 minutes to obtain Sample E and Sample F, respectively.

  Table 4 shows the GABA content of Sample C to Sample F. The experimental data of sample C and sample D are the same experimental data as the experimental data of Example 4. From the results in Table 4, it was found that the content of GABA did not change when manufactured using citrate buffer or when using water. In addition, about the pH of the sample E and the sample F, even if it manufactured with the buffer solution of pH 5.0, pH immediately after manufacture was pushed back to 6.08. For this reason, the pH of Sample E and Sample F was not maintained in a lowered state, and the activity of glutamate decarboxylase was not sufficiently increased to increase the GABA concentration, so the GABA content did not increase. It is considered a thing.

  Moreover, when the soy milk after holding was left overnight, precipitation occurred. From this, when pH was lowered | hung with an acid, in order to preserve | save soymilk stably, it was thought that readjustment of pH was required as an additional process.

<Test 6: Difference in GABA amount in soymilk with or without addition of pyridoxal phosphate>
Unsterilized soymilk was obtained in the same manner as in Example 1. Thereafter, 12.3 mg of pyridoxal phosphoric acid per 100 ml of unsterilized soymilk was added and held at 25 ° C. and 65 ° C. for 20 minutes each (sample G and sample H). Soy milk without addition of pyridoxal phosphate was similarly held at 25 ° C. and 65 ° C. (Sample I, Sample J).

  It is known that pyridoxal phosphate acts as a coenzyme in the glutamic acid decarboxylation (GAD) reaction that produces GABA from glutamic acid. As shown in Table 5, it was confirmed that when pyridoxalphosphoric acid was added after the production, the amount of GABA produced was significantly increased particularly at a high temperature zone (65 ° C.).

  The soy milk obtained by the production method of the present invention contains a large amount of GABA, has a high nutritional value, and is excellent in flavor and easy to drink. Can be prevented or reduced. Moreover, it can utilize for the food-drinks field | area for the prevention and reduction of various physical conditions, such as high blood pressure, a disease, etc., and maintaining health.

Claims (7)

A liquefaction step of obtaining a mixed solution of soybean ground material and water, or a solution obtained by removing water-insoluble components from the mixed solution;
A pH reduction step of reducing the pH of the mixed solution or the solution to near the optimum pH of glutamic acid decarboxylase in the mixed solution or the solution;
Maintaining the lowered pH in the vicinity of the optimum pH, and holding for a certain period of time under conditions where precipitation does not occur in the mixed solution or the solution;
A pH raising step of raising the lowered pH to a predetermined pH after the holding step.   The pH is lowered to a range of 5.6 to 6.1 in the pH lowering step, and the lowered pH is maintained in a range of 5.6 to 6.1 in the holding step. Soymilk manufacturing method.   The method for producing soymilk according to claim 1 or 2, wherein the holding time in the holding step is from 30 minutes to 240 minutes.   The method for producing soymilk according to any one of claims 1 to 3, wherein in the pH raising step, the pH is raised to 6.4 or more.   The method for producing soymilk according to any one of claims 1 to 4, wherein in the pH reduction step, the pH is lowered by dissolving carbon dioxide in the mixed solution or the solution.   The method for producing soymilk according to claim 5, wherein in the pH raising step, the mixed liquid or the solution is heated to degas dissolved carbon dioxide to raise the pH.   The method for producing soymilk according to any one of claims 1 to 6, further comprising an addition step of adding pyridoxalphosphoric acid before the holding step.