JP2019195289A - Manufacturing method of natto - Google Patents

Abstract

To provide a manufacturing method of natto having stringiness and umami equal to or more than those of natto obtained under conventional conditions of fermentation temperature and fermentation time.SOLUTION: A manufacturing method of natto has a fermentation process for adding glutamic acid to a cooked soybean and fermenting the same with Bacillus natto. In the fermentation process, fermentation is conducted at a temperature of 37°C to 47°C for 5 hr. to 11 hr when the cooked soybean is ground soybean, and conducted at the temperature of 37°C to 47°C for 7 hr. to 13 hr. when the cooked soybean is whole soybean.SELECTED DRAWING: None

Description

  The present invention relates to a method for producing natto.

  Natto is produced by fermenting steamed soybeans with Bacillus natto under a temperature condition of about 37 ° C. to 47 ° C. for a time of about 15 hours to 18 hours. For the purpose of improving the quality of natto such as stringiness, for example, various additives have been studied and fermentation conditions have been controlled (see, for example, Patent Document 1).

In addition, natto is increased by producing excellent components due to the action of natto bacteria during fermentation. Among them, vitamin K2 (particularly menaquinone-7) is abundant in natto and is known as a component having an important function for bone formation. Vitamin K2 is a component that is hardly contained in boiled beans and is contained in a large amount by the action of natto bacteria during fermentation.
On the other hand, vitamin K weakens the function of warfarin, an anticoagulant. Therefore, patients suffering from venous thrombosis, myocardial infarction, pulmonary embolism, cerebral embolism, cerebral thrombosis, etc. should refrain from taking natto containing a lot of vitamin K2 in patients taking warfarin. There are many cases instructed by doctors, and there is a demand for the development of natto with reduced vitamin K2 content that can be taken by patients taking warfarin.

  Examples of a method for reducing the content of vitamin K2 in natto include a method using natto bacteria whose vitamin K2 productivity is lower than that of normal natto bacteria (for example, see Patent Document 2).

JP 2006-166812 A JP 2006-069773 A

  Generally, in order to improve the production efficiency, if the fermentation time is made shorter than the normal fermentation time (15 hours or more and about 18 hours or less), natto unique to natto has a weak stringiness, umami, etc., and there is a problem in quality. Had. Therefore, there has been a demand for a method for producing natto that has the same or better quality as ordinary natto while improving production efficiency.

  Moreover, in the method exemplified above as a method for reducing the vitamin K2 content in natto, the overall metabolism of natto bacteria is often reduced, and the balance of flavor such as stringiness and umami of natto is lost. It had the problem that.

  This invention is made | formed in view of the said situation, Comprising: The manufacturing method of the natto which has the stringiness and umami which are equal to or more than the natto obtained on the conditions of the conventional fermentation temperature and fermentation time is provided.

  As a result of intensive research to achieve the above object, the present inventors added glutamic acid to steamed soybeans, and fermented with natto bacteria under conditions shorter than the conventional fermentation time. It has been found that natto having a stringiness and umami equivalent to natto obtained under conditions of temperature and fermentation time can be obtained, and the present invention has been completed.

That is, the present invention includes the following aspects.
The method for producing natto according to the first aspect of the present invention is a method comprising a fermentation process in which glutamic acid is added to steamed soybeans and fermented with natto bacteria, and in the fermentation process, the steamed soybeans are ground soybeans. When fermentation is performed at a temperature of 37 ° C. or higher and 47 ° C. or lower for 5 hours or longer and 11 hours or shorter. I do.
In the fermentation step, the addition amount of the glutamic acid may be 0.1% by mass or more and 5% by mass or less based on the mass of the steamed soybean.
In the natto manufacturing method according to the first aspect, the natto viscosity measured by the following measurement method may be 30 mPa · s or more.
(Measuring method)
Add about 200g to 250g of distilled water kept at 25 ° C to 150g of natto and mix 10 times to loosen the natto. Next, distilled water is added until the total mass of the added water reaches 600 g and mixed 30 times. After confirming that no natto lumps remain, mix 30 more times and let stand in a thermostat set at 25 ° C. for 20 minutes. After 20 minutes, the natto-containing solution is mixed 60 times. Subsequently, it is left still for 20 minutes in the thermostat set to 25 degreeC again. After 20 minutes, the natto-containing solution is mixed 30 times. Next, the 14-mesh colander is used to separate the beans from the viscous liquid. Next, the obtained viscous liquid is transferred to a 1 L glass beaker, and the viscosity is measured using a C-type viscometer.
In the method for producing natto according to the first aspect, the vitamin K2 content in the natto may be less than 350 μg per 100 g of the natto wet.
In the method for producing natto according to the first aspect, the Bacillus natto may be Bacillus subtilis TTCC2051 strain (accession number NITE P-02647).

  The microorganism according to the second aspect of the present invention is Bacillus subtilis TTCC2051 strain (Accession No. NITE P-02647).

  According to the manufacturing method of the said aspect, the natto which has the stringiness and umami equivalent to or more than the natto obtained on the conditions of the conventional fermentation temperature and fermentation time is obtained. Moreover, the obtained natto has a long shelf life and the vitamin K2 content is reduced as compared with natto obtained under the conditions of conventional fermentation temperature and fermentation time. The microorganism of the above aspect is Bacillus natto having lower vitamin K2 productivity than ordinary Bacillus natto.

It is a graph which shows the change of vitamin K2 content during fermentation of natto. It is a graph which shows content of vitamin K2 in natto from which fermentation time in Example 1 differs. It is a graph which shows the viscosity of natto from which fermentation time in Example 1 differs. It is a graph which shows the sensory evaluation result of the stickiness of natto from which fermentation time in Example 1 differs. It is a graph which shows the viscosity after 3 days and 18 days preservation | save of the natto fermented in the short time or normal time, the glutamic acid addition condition or the non-addition condition using the round soybeans in Example 3. Organic acids (isovaleric acid and isoforms) stored after 3 days, 10 days, and 18 days of natto fermented with whole soybeans in Example 3 for a short time or normal time, with or without glutamic acid added. It is a graph which shows content of butyric acid. Of free amino acids (glutamic acid and other free amino acids) after storage for 3 days and 18 days of natto fermented under conditions of addition or no addition of glutamic acid using whole soybeans in Example 3 It is a graph which shows content. It is a graph which shows the viscosity of the natto fermented in the short time (10 hours) or normal time (17 hours), the glutamic acid addition conditions, or the non-addition conditions using the thin soybeans in Example 4. It is a graph which shows the viscosity after 1 day preservation | save of the fermented natto fermented in the short time (6, 8 or 10 hours) or normal time (17 hours) and glutamic acid addition conditions using the fine soybean in Example 4. It shows the content of isovaleric acid immediately after fermentation of natto fermented under the conditions of adding glutamic acid for a short time (6, 8 or 10 hours) or normal time (17 hours) using ground soybean in Example 4. It is a graph. Organic acid immediately after fermentation of natto fermented under conditions of adding glutamic acid or not adding glutamic acid for a short time (10 hours) or normal time (17 hours) using the soy soybean in Example 4 (isovaleric acid and It is a graph which shows content of (isobutyric acid). After 1 day, 8 days and 15 days of storage of natto fermented under the conditions of adding glutamic acid with or without adding a short time (10 hours) or normal time (18 hours) using the fine soybeans in Example 4. It is a graph which shows content of organic acid (isovaleric acid and isobutyric acid). After 1 day, 8 days and 15 days of storage of natto fermented under conditions of adding glutamic acid with or without adding short time (10 hours) or normal time (17 hours) using the fine soybeans in Example 4. It is a graph which shows content of free amino acids (glutamic acid and other free amino acids). It is a graph which shows the content of vitamin K2 in natto fermented under the conditions where glutamic acid is added or not added using a vitamin K2 low-producing strain in Example 5 for a short time or normal time. It is a graph which shows the viscosity of the natto fermented on the vitamin K2 low production strain | stump | stock in Example 5 in the short time or normal time, glutamic acid addition conditions, or non-addition conditions. It is a graph which shows the sensory evaluation result of the stickiness of natto fermented using vitamin-K2 low production strains in Example 5 for a short time or a normal time, with or without the addition of glutamic acid.

≪Natto production method≫
The method for producing natto according to this embodiment includes a fermentation process in which glutamic acid is added to steamed soybeans and fermented with natto bacteria. In the fermentation process, when the steamed soybean is finely ground soybean, fermentation is performed at a temperature of 37 ° C. to 47 ° C. for 5 hours to 11 hours. Or when steamed soybean is whole soybean, it ferments at the temperature of 37 degreeC or more and 47 degrees C or less for 7 hours or more and 13 hours or less.

According to the production method of the present embodiment, the stringiness is equal to or better than that of natto obtained under the conditions of conventional fermentation temperature (about 37 ° C to about 47 ° C) and fermentation time (about 15 hours to about 18 hours). Natto with umami taste is obtained.
In this specification, “stringiness” is one of the sensory characteristics of natto. A professional evaluator familiar with sensory evaluation of natto performs sensory evaluation using the scoring method shown in the examples described later, and the stringiness of natto obtained by the manufacturing method of this embodiment and the conventional fermentation temperature And the stringiness of natto obtained under the conditions of fermentation time can be compared. In addition, the scale of evaluation is as showing in the below-mentioned Example.
The stringiness can also be evaluated by the viscosity of natto. The viscosity of natto obtained by the production method of the present embodiment is preferably 30 mPa or more, and more preferably 35 mPa or more. The measuring method of a viscosity is as showing in the below-mentioned Example.

  In addition, the unique smell of natto is a cause of difficulty for people who are not good at natto, and even those who eat natto have a unique smell that limits the opportunity (time and place) to eat natto. Therefore, there has been a demand for a new technology and a new manufacturing method for natto odor control technology, development of natto with reduced odor, and production technology of natto with less deterioration while suppressing the quality of natto.

On the other hand, the natto obtained by the manufacturing method of the present embodiment has reduced unique odor of natto and has a long shelf life.
In the present specification, “long-lasting” means that the amount of change over time of the appearance, taste, aroma, and stringiness of natto is small. Further, “long-life” can be quantified by evaluating the amount of change over time by sensory evaluation of the appearance, taste, aroma, and stringiness of natto. Specifically, with regard to the appearance, taste, fragrance, and stringiness of natto, a professional evaluator who is familiar with sensory evaluation of natto performs sensory evaluation using the scoring method shown in the examples described later. Thus, it is possible to compare the shelf life of natto obtained by the production method of the present embodiment with the shelf life of natto obtained under the conditions of conventional fermentation temperature and fermentation time. In addition, the scale of evaluation is as showing in the below-mentioned Example.

In particular, in the natto obtained by the production method of the present embodiment, the amount of organic acids (particularly isovaleric acid and isobutyric acid), which are components that affect the odor of natto, is less than that of natto obtained by the conventional production method. The unique smell of natto has been reduced. In addition, in natto obtained by the production method of the present embodiment, the content of organic acids (particularly isovaleric acid and isobutyric acid) that are components that affect the odor of natto and free amino acids that are components that affect the taste The amount of change over time is small, and the shelf life is good. Although this mechanism of action is unclear, the fermentation time is stopped at an early stage by making the fermentation time shorter than before, so that the fermentation activity of Bacillus natto is suppressed, so that it can be stored at a low temperature of about 10 ° C. or less. It is presumed that natto can be obtained, which is difficult to proceed at times, is more stable, and is less likely to change over time.
The contents of organic acids (particularly, isovaleric acid and isobutyric acid) and free amino acids in natto can be measured by high performance liquid chromatography as shown in the examples described later.

Moreover, in the natto obtained by the production method of the present embodiment, the content of vitamin K2 is reduced as compared with natto obtained under the conditions of conventional fermentation temperature and fermentation time.
FIG. 1 is a graph showing changes in vitamin K2 content during fermentation of natto. The present inventors pay attention to the fact that the production of vitamin K2 by Bacillus natto is after 12 hours from the start of fermentation, and that natto with reduced vitamin K2 can be obtained by making the fermentation time shorter than 12 hours. I found it for the first time. Therefore, according to the production method of the present embodiment, natto with a reduced vitamin K2 content is obtained as compared with natto obtained under the conditions of conventional fermentation temperature and fermentation time.
In the present specification, “vitamin K2” means menaquinone-7. Therefore, in the Example etc. which are mentioned later, the amount of menaquinone-7 contained in 100 g of wet natto is measured and calculated as the vitamin K2 content in natto.
Details of the process of the method for producing natto according to this embodiment will be described below.

<Fermentation process>
In the fermentation process, glutamic acid is added to steamed soybeans and fermented with natto bacteria.

[Steamed soybeans]
Steamed soybeans can be prepared using known methods. Specifically, the method for producing steamed soybean includes a dipping process and a steaming process. In the dipping step, when the soybean is whole soybean, the dipping time can be, for example, 10 hours to 22 hours, and preferably 14 hours to 18 hours. Further, when the soybean is fine soybean, the immersion time can be, for example, 2 hours or more and 5 hours or less, and preferably 3 hours or more and 4 hours or less. In addition, the immersion temperature can be set to, for example, 15 ° C. or higher and 30 ° C. or lower, and preferably 18 ° C. or higher and 22 ° C. or lower, in both round soybeans and ground soybeans. In the cooking step, the cooking temperature can be, for example, about 100 ° C. to 140 ° C., and the cooking time can be, for example, 5 minutes to 90 minutes. Moreover, the pressure in a cooking process can be 0.02 MPa or more and 0.28 MPa or less.
Further, the steamed soybean used in the fermentation process may be whole soybeans or ground soybeans. Here, “round soybean” means soybean that does not undergo the step of breaking soybean.
Moreover, the soybean used in the fermentation process is not particularly limited, and it can be produced domestically or overseas. In addition, a wide range of particle sizes is applied, including large to very small particles, and is not limited. Moreover, soybean is not limited to yellow soybean, but can be applied to colored beans such as black soybean and green soybean.
In the production method of the present embodiment, the beans used as a raw material for natto are not limited to soybeans (beans belonging to the genus Soybean), but contain protein or protein and sugar and are fermented by natto bacteria and yarn. Those having a pulling property can be used. Specific examples of such beans include beans belonging to the genus of kidney beans such as platinum bean, gold bean, quail, tiger bean and white flower bean.

[Glutamic acid]
Examples of glutamic acid used in the fermentation process include glutamic acid or a salt thereof. Examples of the glutamate include sodium glutamate, potassium glutamate, magnesium glutamate, and calcium glutamate. In addition, for example, foods rich in glutamic acid such as extracts such as kelp, seaweed, dried shiitake, and tomato may be used instead of glutamic acid.

0.1 mass% is preferable with respect to the mass of steamed soybean, and, as for the lower limit of the addition amount of glutamic acid in a fermentation process, 0.5 mass% is more preferable. By setting the lower limit of the amount of glutamic acid added to the above lower limit or more, a natto having a viscosity and stringiness equal to or higher than that of natto obtained under the conditions of conventional fermentation temperature and fermentation time can be obtained.
On the other hand, the upper limit of the addition amount of glutamic acid is not particularly limited, but is preferably 5% by mass from the viewpoint of the above-mentioned effects of improving the viscosity and the stringiness and the production cost. The following is preferred.
As a method for adding glutamic acid, when glutamic acid is in a dry state such as a powder, for example, a method in which the glutamic acid powder or the like is directly sprayed on steamed soybeans may be used. Alternatively, in the case of a liquid state such as an aqueous solution containing glutamic acid, for example, a method of spraying the glutamic acid solution onto steamed soybean, a method of immersing soybean in a solution to which glutamic acid has been added during the production of steamed soybean, and the like can be mentioned.

[Natto bacteria]
The Bacillus natto used in the fermentation process is not particularly limited as long as it is an edible Bacillus subtilis. Natto bacteria generally used for natto production may be used, or natto bacteria contained in commercially available natto may be used. Alternatively, various improved strains improved to improve the sensory characteristics of natto may be used. Examples of Bacillus natto commonly used in natto production include Miyagino and Naruse, which are commercially available bacteria, and similar bacteria. Examples of the improved strain include natto bacteria having a lower productivity of vitamin K2 than conventional natto bacteria (hereinafter sometimes referred to as “vitamin K2 low-producing strains”). By using a vitamin K2 low-producing strain, it is possible to produce natto in which the content of vitamin K2 is reduced to such an extent that a patient taking warfarin can contact it. In addition, as a selection method of a vitamin K2 low production strain, the method described in a well-known document (the said patent document 2) etc. can be used. Specifically, this is as shown in the examples described later.
Among these, Bacillus subtilis TTCC2051 strain (Accession No. NITE P-02647) is preferably used as a vitamin K2 low-producing strain. This TTCC2051 strain was deposited on February 23, 2018 at the Patent Microorganism Depositary Center for Product Evaluation Technology, an independent administrative agency. Further, TTCC2051 strain has bacteriological properties as shown in Examples described later, and is confirmed to be Bacillus natto.
By using the TTCC2051 strain, natto with reduced vitamin K2 content can be obtained.

[Fermentation conditions]
In the fermentation process, when the steamed soybean is ground soybean, the fermentation temperature can be 37 ° C. or higher and 47 ° C. or lower, and preferably 38 ° C. or higher and 44 ° C. or lower. Moreover, fermentation time can be made into 5 hours or more and 11 hours or less, 5.5 hours or more and 11 hours or less are preferable, 6 hours or more and 11 hours or less are more preferable, and 7 hours or more and 11 hours or less are more preferable.
On the other hand, when the steamed soybean is whole soybean, the fermentation temperature can be 37 ° C. or higher and 47 ° C. or lower, and preferably 38 ° C. or higher and 44 ° C. or lower. Moreover, fermentation time can be 7 hours or more and 13 hours or less, and 9 hours or more and 12 hours or less are preferable.
The fermentation time in the above-mentioned ground soybean or whole soybean is shorter than the fermentation time (about 15 hours or more and 18 hours or less) of the conventional method for producing natto. Therefore, by using the natto manufacturing method of the present embodiment, the operating rate of the fermentation chamber can be improved and natto can be manufactured efficiently. Specifically, by setting the fermentation time to 12 hours or less, the fermentation chamber can be used twice a day, and the production amount per the same area can be doubled.
Moreover, fermentation can be complete | finished by setting it as the low temperature of 10 degrees C or less.
In addition, it can carry out on the fermentation conditions at the time of normal natto manufacture except the said fermentation temperature and the said fermentation time.

[Vitamin K2 content]
The vitamin K2 content in natto obtained using the method for producing natto of this embodiment is preferably less than 350 μg per 100 g of natto wet, and more preferably 325 μg or less. When the vitamin K2 content is not more than the above upper limit value, natto can be eaten more safely in patients taking warfarin.
In addition, the vitamin K2 content in natto can be measured by a high performance liquid chromatographic method as shown in Examples described later.

  EXAMPLES Hereinafter, although an Example demonstrates this invention, this invention is not limited to a following example.

[Example 1] Addition of glutamic acid and examination of fermentation time (1) Fermentation process 2 kg of very small soybean (particle size: about 5.0 mm or more and 5.6 mm or less) was gently washed. Next, about 3 times the amount of tap water was added to the bean mass, and immersed for 18 hours at 20 ° C. Next, the soaked beans were heated while immersed in water, and after reaching 130 ° C., they were cooked for 21 minutes. In addition, a 30% by mass-containing glutamic acid solution was prepared in advance. Next, this sodium glutamate solution was added to 5.0% by mass of the steamed soybean (that is, the final concentration of sodium glutamate in the steamed soybean was 1.5% by mass). Next, as a natto bacterium, a similar bacterium of Miyagino, which is a commercially available bacterium, was used, and about 50 g of steamed soybean added with glutamic acid was filled in a PSP container and fermented. As fermentation conditions, sampling was performed 9, 10, and 18 hours after the start of fermentation under fermentation program conditions of 38 ° C. or higher and 42 ° C. or lower.

(2) Measurement of vitamin K2 Water was added to natto for each fermentation time sampled in (1), and the sample was homogenized. About 0.8 g or more and 2.0 g or less of the sample was put in a mortar, 3 g of sea sand and 80 mL of methanol were added, and this was ground and extracted in several batches. Next, the solution was suction filtered through an 11G3 glass filter, and the resulting solution was transferred to a 100-mL volumetric flask and fixed with methanol. Next, the content of vitamin K2 in each sample was measured by a high performance liquid chromatograph method under the following measurement conditions, and the content per 100 g of wet natto was calculated. The result is shown in FIG. 2A.

(Measurement conditions for high performance liquid chromatography)
Measuring apparatus: High performance liquid chromatograph (LC-20AT, manufactured by Shimadzu Corporation)
Detector: Fluorescence spectrophotometer (RF-20AXS, manufactured by Shimadzu Corporation)
Column: L-column ODS, φ4.6 mm × 250 mm (manufactured by the Chemical Substance Evaluation Research Organization)
Column temperature: 40 ° C
Mobile phase: Mixture of methanol and ethanol (methanol: ethanol = 7: 3, volume ratio)
Flow rate: 1.0 mL / min Measurement wavelength: excitation wavelength 240 nm, fluorescence wavelength 430 nm
Injection volume: 50 μL
Reduction column: Platinum column (RC-10, φ4.0 mm × 15 mm, manufactured by Shiseido Co., Ltd.)

(3) Measurement of Viscosity About 150 g of distilled water kept at 25 ° C. was added to about 150 g of natto for each fermentation time sampled in (1), and mixed 10 times to loosen natto. Next, distilled water was added until the total mass of the added water reached 600 g and mixed 30 times. After confirming that no natto lumps remained, the mixture was further mixed 30 times and allowed to stand in a thermostat set at 25 ° C. for 20 minutes. After 20 minutes, the natto-containing solution was mixed 60 times. Subsequently, it was left still for 20 minutes in the thermostat set to 25 degreeC again. After 20 minutes, the natto-containing solution was mixed 30 times. The beans and sticky liquid were then separated using a 14 mesh colander. Next, the obtained viscous liquid was transferred to a 1 L glass beaker, and the viscosity was measured using a C-type viscometer (manufactured by Toki Sangyo Co., Ltd., TVC-7 type viscometer). The viscosity was measured several times, and the average value was used as the viscosity. The result is shown in FIG. 2B.

(4) Sensory evaluation of natto stickiness The natto stickiness of each fermentation time sampled in (1) was sensory evaluated by a scoring method. The scale of stickiness is as follows.
(Measure of stickiness)
6: Stir, lift with chopsticks and shake, the amount of yarn is sufficient.
5: Lifting up with chopsticks will lift up and will not fall even if shaken.
4: The whole lifts up.
3: Yarn is connected and half is lifted.
2: Stickiness is seen and the thread is slightly pulled.
1: Not sticky.

In addition, evaluation was conducted by a specialist evaluator who selected panelists capable of distinguishing basic five tastes (sweet, salty, sour, bitter, umami) from within the company and repeatedly conducted training for natto evaluation for more than half a year.
The numerical value showed the average value of the evaluation result of n = 3. The results are shown in FIG. 2C for the sticky sensory evaluation, and Table 1 shows the results of collecting comments such as appearance and flavor.

From FIG. 2A, the tendency for content of vitamin K2 to decrease was seen, so that fermentation time was short. In addition, it was revealed that natto fermented under glutamic acid-added conditions has a lower vitamin K2 content than natto fermented under glutamic acid-free conditions.
Moreover, from FIG. 2B and FIG. 2C, in the natto fermented on glutamic acid addition conditions, the tendency for a viscosity to increase is seen rather than the natto fermented on glutamic acid addition conditions, and the sensory evaluation of stickiness tends to become high. It was observed. In natto fermented for 9 hours or 10 hours under glutamic acid addition conditions, the sensory evaluation of viscosity and stickiness was similar to that of natto fermented for 18 hours under no glutamic acid addition conditions, and the appearance and flavor were also similar.
From the above, natto fermented for a short time of about 9 to 10 hours under glutamic acid addition conditions has reduced vitamin K2 content and fermented under normal fermentation conditions (glutamate-free addition and 18-hour fermentation). It became clear that it had the same stickiness and flavor as natto.

[Example 2] Examination of glutamic acid addition amount (1) Fermentation process 30% by mass of sodium glutamate solution is 5.0% by mass with respect to steamed soybean (ie, the final concentration of sodium glutamate in the steamed soybean is 1.5% by mass) Instead of adding so that the 30% by mass sodium glutamate solution is 3.0% by mass with respect to the steamed soybean (ie, the final concentration of sodium glutamate in the steamed soybean is 0.9% by mass). ) Except for the addition, fermentation was performed using the same method as in (1) of Example 1, and sampled 9, 10, and 18 hours after the start of fermentation.

(2) Measurement of Viscosity About natto for each fermentation time sampled in (1), the viscosity was measured using the same method as (4) of Example 1. The results are shown in Table 2 below.

(3) Sensory evaluation of natto stickiness The natto stickiness of each fermentation time sampled in (1) is shown as a ratio when the conventional manufacturing method is 100%. The sensory evaluation was performed using the same method as in Example 1 (5). The results are shown in Table 2 below. Table 2 also shows the results of aggregating comments such as appearance and flavor.

  From Table 2, even in natto fermented for 9 hours or 10 hours with sodium glutamate added so that the final concentration of sodium glutamate in the steamed soybean is 0.9% by mass, it is fermented for 18 hours under the condition where glutamate is not added. It was a sensory evaluation of the same viscosity and stickiness as the natto, and it was confirmed that the appearance and flavor were also the same.

[Example 3] Examination of stringiness and shelf life of natto with glutamic acid addition and short-time fermentation using whole soybean (1) Fermentation process Very small soybean (particle size: about 5.0 mm to 5.6 mm or less) 2 kg Lightly washed. Next, about 3 times the amount of tap water was added to the bean mass, and immersed for 18 hours at 20 ° C. Next, the soaked beans were heated while immersed in water, and after reaching 130 ° C., they were cooked for 23 minutes. Further, a glutamic acid solution containing 15% by mass was prepared in advance. Next, fermentation was performed under any one of the following fermentation conditions 1) to 4). In addition, as for Bacillus natto, a similar bacterium of Miyagino which is a commercially available bacterium was used under any fermentation conditions. Further, after the fermentation was completed, it was stored in a 10 ° C. thermostat for 3, 10 and 18 days.
(Fermentation conditions)
1) Normal fermentation method: No addition of glutamic acid, fermentation for about 17 hours with a fermentation program of 38 ° C. to 42 ° C. Hereinafter, it may be simply described as “normal” in the drawings and the like.
2) Short-time fermentation method: no addition of glutamic acid, fermentation at 44 ° C. for 10 hours. Hereinafter, in drawings and the like, it may be simply described as “short time”.
3) Addition of glutamic acid / normal fermentation method: Add 15% by weight sodium glutamate-containing solution to steamed soybean at 3.0% by weight (that is, so that the final concentration of sodium glutamate in steamed soybean is 0.45% by weight) Fermentation for about 17 hours with a fermentation program of 38 ° C to 42 ° C. Hereinafter, in drawings and the like, it may be simply described as “Glu addition”.
4) Glutamic acid addition / short-time fermentation method: 3.0% by mass of 15% by weight sodium glutamate-containing solution with respect to steamed soybean (that is, the final concentration of sodium glutamate in steamed soybean is 0.45% by weight) Addition, fermentation at 44 ° C for 10 hours. Hereinafter, in drawings and the like, it may be simply referred to as “Glu short time”.

(2) Measurement of Viscosity For each natto stored for 3 days and 18 days, the viscosity was measured using the same method as (4) of Example 1. The results are shown in FIG. 3A. In FIG. 3A, “D + 3” is natto with a storage period of 3 days, and “D + 18” is natto with a storage period of 18 days.

(3) Sensory evaluation of natto Sensory evaluation was performed by scoring method regarding the appearance, taste, fragrance and stringiness of natto. The sensory evaluation method was performed with reference to the method described in the Natto test method (Kotsumi Co., Ltd., issued on March 20, 1990). The scale conversion of each evaluation item is as follows. A score of 2.5 or less was a problem as the quality of natto, and a score of 2 or less was evaluated as being considered to be an unsuitable product level.
(Scale)
1) Appearance A: The thickness of the fungus cover is thick, the bean color is bright, and no lysis is observed.
B: The bacteria cover is slightly thin. Bean color is a little dark. Lysis in part.
C: The bacteria cover is thin. The bean color is dark. Whole lysis.
D: Almost no bacterial coverage. The bean color is dark. The whole is dry. The lysed lysate as a whole.
2) Taste A: There is no off-flavor such as bitterness, astringency, and savory taste. Moderate taste.
B: A little bitter tastes such as bitterness, astringency and savory taste are felt. I feel the taste of aging.
C: The taste of bitterness and astringency is felt. I strongly feel the old taste of aging.
D: The taste of bitterness and astringency is very strong. The old taste is very strong.
3) Scent A: No odor B: A natto odor is felt slightly strong C: A natto odor is felt strongly Feeling a strange odor D: The natto odor is very strong. Strong odor.
4) Thread pulling property A: Stir and lift with chopsticks to lift the whole and do not fall for more than 2 seconds.
B: Lifting with chopsticks lifts up, but falls within 2 seconds.
C: Stir and everything will not lift. Slightly less yarn. The elasticity is weak.
D: It does not lift up when lifted, the amount of yarn is small, and there is no elasticity.

(Scale scale conversion)
A ⁺ : 5.5 points, A: 5 points, A ⁻ : 4.5 points, B ⁺ : 4 points, B: 3.5 points, B ⁻ : 3 points, C ⁺ : 2.5 points, C: 2 points, C ⁻ : 1.5 points, D: 1 point

In addition, the evaluation was performed by two expert evaluators who selected panelists capable of distinguishing basic five tastes (sweet, salty, sour, bitter, umami) from within the company, and repeatedly conducted training on natto evaluation for more than half a year. It was.
The results of evaluation by two people are shown in Table 3 below. In Table 3, “D + 3” is natto with a storage period of 3 days, “D + 10” is natto with a storage period of 10 days, and “D + 18” is natto with a storage period of 18 days.

(4) Measurement of organic acids (isovaleric acid and isobutyric acid) The content of organic acids (isovaleric acid and isobutyric acid) in each natto stored for 3 days, 10 days and 18 days was measured under the following measurement conditions. The amount was analyzed and quantified by a high performance liquid chromatograph method and converted into the content per 100 g of wet natto. The results are shown in FIG. 3B. In FIG. 3B, “D + 3” is natto with a storage period of 3 days, “D + 10” is natto with a storage period of 10 days, and “D + 18” is natto with a storage period of 18 days.

  The measurement by the high performance liquid chromatograph method was performed according to the following procedure. First, sampled natto for each fermentation time was made uniform in a paste form. About 5 g of the sample was precisely weighed in a glass tube centrifuge tube, 10 mL of an extract (0.1 N HCl + 0.5% perchloric acid) was added, and the mixture was ground and extracted using a spatula. Further, 5 mL of the extract was added, followed by extraction with shaking for 30 minutes. Subsequently, the mixture was centrifuged (3000 rpm, 10 minutes), and the resulting supernatant was taken in a volumetric flask. On the other hand, the residue was further extracted with 3 mL of extract and centrifuged three times, and the resulting supernatants were combined and made up to 25 mL with the extract. The solution was filtered through a 0.45 μm pore size membrane filter and subjected to a high performance liquid chromatograph under the following conditions.

(Measurement condition)
Measuring device: Organic acid analysis system Prominence (manufactured by Shimadzu Corporation)
Column: Shim-Pack SCR-102H
Column temperature: 52 ° C
Mobile phase: 5 mmol / L p-toluenesulfonic acid aqueous solution Reaction solution: 5 mmol / L p-toluenesulfonic acid, 0.1 mmol / L EDTA-4H, 20 mmol / L Bis-Tris mixed aqueous solution Flow rate: 0.8 mL / Min

(5) Measurement of free amino acids The content of free amino acids in each natto stored for 3 days and 18 days was analyzed and quantified by high performance liquid chromatography under the following measurement conditions to obtain the content per 100 g of natto wetness. Converted. The results are shown in FIG. 3C. In FIG. 3C, “D + 3” is natto with a storage period of 3 days, and “D + 18” is natto with a storage period of 18 days. “Glu” means glutamic acid.

  The measurement by the high performance liquid chromatograph method was performed according to the following procedure. First, sampled natto for each fermentation time was made uniform in a paste form. About 0.1 g of the sample was precisely weighed in a glass tube centrifuge tube, and 5 mL of 70% ethanol was added and ground and extracted using a spatula. Further, after adding 5 mL of 70% ethanol, the mixture was extracted by shaking for 2 hours. Subsequently, the mixture was centrifuged (3000 rpm, 10 minutes), and the resulting supernatant was taken in a volumetric flask. On the other hand, extraction and centrifugation of the residue were further repeated 3 times with 4 mL of 70% ethanol, and the resulting supernatants were combined and adjusted to a volume of 25 mL with 70% ethanol. The solution was filtered through a 0.45 μm pore size membrane filter and subjected to a high performance liquid chromatograph under the following conditions.

(Measurement condition)
Measuring apparatus: High-performance liquid chromatograph (LC-VP, Prominence Li type, manufactured by Shimadzu Corporation)
Detector: Fluorescence spectrophotometer (RF-20AXS, manufactured by Shimadzu Corporation)
Column: Shim-Pack Amino-Li (manufactured by Shimadzu Corporation)
Column temperature: 39 ° C
Mobile phase: Amino acid mobile phase kit Li type Mobile phase flow rate: 0.6 mL / min Reaction solution: Amino acid analysis kit OPA reagent Reaction solution flow rate: 0.2 mL / min Measurement wavelength: excitation wavelength 350 nm, fluorescence wavelength 450 nm

From FIG. 3A, the viscosity was improved even in short-time fermentation by addition of glutamic acid, which was similar to the viscosity of normal fermentation without addition of glutamic acid. In addition, natto fermented for a short time with glutamic acid added had a smaller decrease in viscosity due to prolonged storage period than natto fermented with glutamic acid and usually fermented. That is, it was confirmed that the shelf life was good with little change from the initial quality.
Moreover, from FIG. 3B and FIG. 3C, content of the organic acid (isovaleric acid and isobutyric acid) and the free amino acid was less in the short-time fermentation than in the normal fermentation, regardless of the presence or absence of addition of glutamic acid. Moreover, the increase width of the generation amount of organic acids (isovaleric acid and isobutyric acid) and free amino acids accompanying a prolonged storage period was also small. Therefore, in short-time fermentation, the natto odor is reduced compared to normal fermentation, and even if the storage period is long, the amount of isovaleric acid that is the cause of odor and the influence on taste From the fact that the amount of free amino acids generated and the amount of change is small, it has become clear that the shelf life is good. Furthermore, it became clear that the low natto viscosity, which is a problem in short-time fermentation, can be improved at the same time by adding glutamic acid.

[Example 4] Examination of stringiness and shelf life of natto with glutamic acid addition and short-time fermentation using ground soybean (1) Examination of fermentation time Ground soybean (particle size: 3.0 mm to 5.3 mm) About) 2 kg was lightly washed. Next, about 3 times the amount of tap water was added to the bean mass, and immersed for 18 hours at 20 ° C. Next, the soaked beans were heated while immersed in water, and after reaching 130 ° C., they were cooked for 23 minutes. Further, a glutamic acid solution containing 15% by mass was prepared in advance. Next, this sodium glutamate solution was added to 3.0% by mass of the steamed soybean (that is, the final concentration of sodium glutamate in the steamed soybean was 0.45% by mass). Next, TTCC904-2 strain (Accession Number NITE P-01705) was used as a natto bacterium, and about 50 g of steamed soybean added with glutamic acid was filled in a PSP container and fermented. As fermentation conditions, it sampled at about 54 g or more and 57 g or less at 44 ° C. or 46 ° C. after 4, 5 or 6 hours from the start of fermentation. Subsequently, sensory evaluation was performed about the stringing property of each sampled natto using the same method as (3) of Example 3. The results are shown in Table 4 below.

  From Table 4, it was clarified that in short-time fermentation using ground soybeans, natto having sufficient viscosity can be obtained when the fermentation time is 5 hours or longer.

(2) Fermentation process 2 kg of ground soybean (particle size: about 3.0 mm or more and 5.3 mm or less) was lightly washed. Next, about 3 times the amount of tap water was added to the bean mass, and immersed for 18 hours at 20 ° C. Next, the soaked beans were heated while immersed in water, and after reaching 130 ° C., they were cooked for 23 minutes. Further, a glutamic acid solution containing 15% by mass was prepared in advance. Next, fermentation was performed under any one of the following fermentation conditions 1) to 4). As natto bacteria, TTCC904-2 strain (Accession Number NITE P-01705) was used under any fermentation conditions. Moreover, after completion | finish of fermentation, it preserve | saved for 1, 8, and 15 days in a 10 degreeC thermostat.
(Fermentation conditions)
1) Normal fermentation method: No addition of glutamic acid, 17 hours or 18 hours fermentation with a fermentation program of 38 ° C. or higher and 42 ° C. or lower. Hereinafter, in the drawings and the like, the fermentation time of 17 hours may be described as “normal”. What fermentation time is 18 hours may be described as "18h".
2) Short-time fermentation method: no addition of glutamic acid, fermentation at 44 ° C. for 10 hours. Hereinafter, in drawings etc., it may be described as “10h” or “short time”.
3) Addition of glutamic acid / normal fermentation method: Add 15% by weight sodium glutamate-containing solution to steamed soybean at 3.0% by weight (that is, so that the final concentration of sodium glutamate in steamed soybean is 0.45% by weight) Fermentation for about 17 hours or 18 hours with a fermentation program of about 38 ° C to 42 ° C. Hereinafter, in the drawings and the like, the fermentation time of 17 hours may be described as “17h + G”, “normal + G”, or “Glu addition”. A fermentation time of 18 hours may be described as “18h + G”.
4) Glutamic acid addition / short-time fermentation method: 3.0% by mass of 15% by weight sodium glutamate-containing solution with respect to steamed soybean (that is, the final concentration of sodium glutamate in steamed soybean is 0.45% by weight) Addition, fermentation at 44 ° C. for 6 hours, 8 hours or 10 hours. Hereinafter, in the drawings and the like, the fermentation time of 6 hours may be described as “6h + G”, and the fermentation time of 8 hours may be described as “8h + G”. Hereinafter, in the drawings and the like, the fermentation time of 10 hours may be described as “10h + G” or “Glu addition short time”.

(3) Viscosity measurement Fermentation process after fermenting under the conditions of natto immediately after fermentation process fermented under conditions 1) to 4) and 3) or 4) (fermenting 6 hours, 8 hours or 10 hours) About natto preserve | saved one day afterward, the viscosity was measured using the method similar to (4) of Example 1. FIG. The result of natto immediately after the fermentation process is shown in FIG. 4A, and the result of natto stored for 1 day after the fermentation process is shown in FIG. 4B. In FIG. 4B, “D + 1” is natto with a storage period of one day.

(4) Sensory evaluation of natto About the external appearance, taste, aroma, and stringiness of natto, sensory evaluation was performed by the scoring method using the same method as (3) of Example 3.

In addition, the evaluation was performed by two expert evaluators who selected panelists capable of distinguishing basic five tastes (sweet, salty, sour, bitter, umami) from within the company, and repeatedly conducted training on natto evaluation for more than half a year. It was.
The results of evaluation by two people are shown in Table 5 below. In Table 5, “D + 1” is natto with a storage period of 1 day, “D + 8” is natto with a storage period of 8 days, and “D + 15” is natto with a storage period of 15 days.

(5) Measurement of organic acids (isovaleric acid and isobutyric acid) Fermented under the conditions of 1) to 4) above fermented natto and fermented under the conditions of 1) to 4) above for 1 day The contents of organic acids (isovaleric acid and isobutyric acid) in natto stored for 8 days and 15 days were analyzed and quantified by high performance liquid chromatography under the same measurement conditions as in Example 3, (4). It was converted into the content per 100 g of natto wet. FIG. 4C shows the results of isovaleric acid content in natto immediately after the fermentation step fermented under the above conditions 3) or 4) (6 hours, 8 hours, or 10 hours fermentation). Moreover, the result of the organic acid (isovaleric acid and isobutyric acid) content in the natto immediately after the fermentation process fermented on the conditions of said 1) -4) is shown to FIG. 4D. Moreover, FIG. 4E shows the contents of organic acids (isovaleric acid and isobutyric acid) in natto fermented under the above conditions 1) to 4) and stored for 1 day, 8 days, and 15 days. In FIG. 4E, “D + 1” is natto with a storage period of 1 day, “D + 8” is natto with a storage period of 8 days, and “D + 15” is natto with a storage period of 15 days.

(6) Measurement of free amino acid The content of free amino acid in natto fermented under the conditions 1) to 4) and stored for 1 day, 8 days and 15 days was the same as in (5) of Example 3. Under measurement conditions, analysis and quantification were performed by high performance liquid chromatography, and the content was converted into a content per 100 g of natto wet. The result is shown in FIG. 4F. In FIG. 4F, “D + 1” is natto with a storage period of 1 day, “D + 8” is natto with a storage period of 8 days, and “D + 15” is natto with a storage period of 15 days. “Glu” means glutamic acid.

From FIG. 4A, it was confirmed that the viscosity was improved by adding glutamic acid. Moreover, from FIG. 4B, it was sufficient viscosity by adding glutamic acid also in natto which fermentation time is shorter than 8 hours and normal fermentation.
Also, from Table 5, fermented under the conditions of 3) or 4) and stored for 1 day, 8 days and 15 days, fermented under the conditions of 1) above, fermented under the conditions of 1), 1 day, 8 days and 15 days It was confirmed that the sensory evaluation results (appearance, taste, fragrance, and stringiness) over time were smaller than stored natto, and the shelf life was good.
Moreover, from FIG. 4C and FIG. 4D, in natto fermented on the conditions of said 4), the fragrance components peculiar to natto, such as isovaleric acid, are suppressed rather than natto fermented on the conditions of said 1). Was confirmed. Furthermore, from FIG. 4E, in the natto fermented under the conditions of 2) or 4), the organic acids (isovaleric acid and isobutyric acid) over time are more natto fermented under the conditions of 1) or 3). It was confirmed that there was little change in the content of and the shelf life was good.
From FIG. 4F, natto fermented under the above conditions 2) or 4) has a lower free amino acid content than natto fermented under the above conditions 1) or 3). It was inferred that the taste would be light, with less amino acids and less miscellaneous taste. In addition, in natto fermented under the above conditions 2) or 4), natto fermented under the above conditions 1) or 3) has less change in free amino acid content over time and does not have a strong taste. It was inferred that there was little deterioration change.

[Example 5] Manufacture of natto using a vitamin K2 low-producing strain (1) Screening for a vitamin K2 low-producing strain TTCC904-2 strain (Accession Number NITE P-01705) was used as a parent strain. This twill strain was inoculated into 100 mL of soy broth and cultured with shaking at 37 ° C. for 16 hours. Subsequently, 10 mL of the culture solution was centrifuged (7000 rpm, 10 minutes) and collected. Subsequently, the microbial cells were washed twice with physiological saline. Next, the washed cells were suspended in 5 mL of physiological saline. Subsequently, mutation was introduced by UV irradiation for 5 minutes while stirring with a stirrer. Subsequently, 50 μL of the microbial cells mutated to 8 mL of tryptic soy broth were inoculated in the dark, and cultured at 37 ° C. for 4 hours in the dark. Subsequently, the culture solution was centrifuged (7000 rpm, 10 minutes), collected, and the obtained cells were suspended in physiological saline. They were then smeared on soy broth plates containing appropriate concentrations of streptomycin, chloramphenicol and vitamin K3 and incubated overnight at 37 ° C. On the next day, the colonies that had grown were purified again using the same medium, and the strain in which growth was observed was selected as a vitamin K2 low-producing strain. As a result of selection, TTCC2051 strain was selected.

(2) Morphological observation of vitamin K2 low-producing strain, 16S rDNA base sequence analysis Identification of the obtained strain of TTCC2051 strain was made by Technosuruga Laboratories, Inc., and morphological observation and 16S rDNA base sequence analysis were performed. Table 6 shows the results of morphological observation of the TTCC2051 strain. From the following results, it was confirmed that the TTCC2051 strain was Bacillus natto. In Table 6, “+” indicates positive and “−” indicates negative.

(3) Manufacture of natto using vitamin K2 low production strain (TTCC2051 strain) 2 kg of very small soybean (particle size: about 5.0 mm or more and 5.6 mm or less) was lightly washed. Next, about 3 times the amount of tap water was added to the bean mass, and immersed for 18 hours at 20 ° C. Next, the soaked beans were heated while immersed in water, and after reaching 130 ° C., they were cooked for 23 minutes. Further, a glutamic acid solution containing 15% by mass was prepared in advance. Next, fermentation was performed under any one of the following fermentation conditions 1) to 4). As natto bacteria, TTCC2051 strain was used under any fermentation conditions.
(Fermentation conditions)
1) Normal fermentation method: No addition of glutamic acid, fermentation for about 17 hours with a fermentation program of 38 ° C. to 42 ° C. Hereinafter, in drawings and the like, it may be simply described as “normal addition without addition”.
2) Short-time fermentation method: no addition of glutamic acid, fermentation at 44 ° C. for 10 hours. Hereinafter, in drawings and the like, it may be simply referred to as “no addition, short-time fermentation”.
3) Addition of glutamic acid / normal fermentation method: Add 15% by weight sodium glutamate-containing solution to steamed soybean at 3.0% by weight (that is, so that the final concentration of sodium glutamate in steamed soybean is 0.45% by weight) Fermentation for about 17 hours with a fermentation program of 38 ° C to 42 ° C. Hereinafter, in drawings and the like, it may be simply described as “normal fermentation with addition”.
4) Glutamic acid addition / short-time fermentation method: 3.0% by mass of 15% by weight sodium glutamate-containing solution with respect to steamed soybean (that is, the final concentration of sodium glutamate in steamed soybean is 0.45% by weight) Addition, fermentation at 44 ° C for 10 hours. Hereinafter, in drawings and the like, it may be simply described as “short-time fermentation with addition”.

(4) Measurement of vitamin K2 About each natto fermented on the fermentation conditions of said 1) -4), content of vitamin K2 was measured using the method similar to (2) of Example 1. FIG. The result is shown in FIG. 5A.

(5) Measurement of viscosity About each natto fermented on the fermentation conditions of said 1) -4), the viscosity was measured using the method similar to (4) of Example 1. FIG. The result is shown in FIG. 5B.

(6) Sensory evaluation of natto stickiness For each natto fermented under the fermentation conditions of 1) to 4) above, sensory evaluation of natto stickiness was performed using the same method as (5) of Example 1. The result is shown in FIG. 5C.

  From FIG. 5A, in the natto fermented under the conditions of 4) above, the content of vitamin K2 was reduced to 272 mg per 100 g of wet natto. Moreover, from FIG. 5B and FIG. 5C, it was confirmed that the natto fermented on the conditions of said 4) has a viscosity and stickiness equal to or more than natto fermented on the conditions of 1) (normal fermentation method).

  According to the manufacturing method of this embodiment, it has stringiness and umami which are equal to or better than natto obtained under the conditions of conventional fermentation temperature and fermentation time. Moreover, the obtained natto has a long shelf life and the vitamin K2 content is reduced as compared with natto obtained under the conditions of conventional fermentation temperature and fermentation time.

Claims (6)

It has a fermentation process in which glutamic acid is added to steamed soybeans and fermented with natto bacteria.
In the fermentation step, when the steamed soybean is ground soybean, fermentation is performed at a temperature of 37 ° C. to 47 ° C. for 5 hours to 11 hours,
When the steamed soybean is whole soybean, a method for producing natto, wherein fermentation is performed at a temperature of 37 ° C. to 47 ° C. for 7 hours to 13 hours.   In the said fermentation process, the addition amount of the said glutamic acid is 0.1 mass% or more and 5 mass% or less with respect to the mass of the said steamed soybean, The manufacturing method of the natto of Claim 1. The method for producing natto according to claim 1 or 2, wherein the viscosity of the natto measured by the following measurement method is 30 mPa · s or more.
(Measuring method)
Add about 200g to 250g of distilled water kept at 25 ° C to 150g of natto and mix 10 times to loosen the natto. Next, distilled water is added until the total mass of the added water reaches 600 g and mixed 30 times. After confirming that no natto lumps remain, mix 30 more times and let stand in a thermostat set at 25 ° C. for 20 minutes. After 20 minutes, the natto-containing solution is mixed 60 times. Subsequently, it is left still for 20 minutes in the thermostat set to 25 degreeC again. After 20 minutes, the natto-containing solution is mixed 30 times. Next, the 14-mesh colander is used to separate the beans from the viscous liquid. Next, the obtained viscous liquid is transferred to a 1 L glass beaker, and the viscosity is measured using a C-type viscometer.   The method for producing natto according to any one of claims 1 to 3, wherein a content of vitamin K2 in the natto is less than 350 µg per 100 g of the wet natto.   The method for producing natto according to any one of claims 1 to 4, wherein the Bacillus natto is Bacillus subtilis TTCC2051 strain (Accession Number NITE P-02647).   Bacillus subtilis TTCC2051 strain (Accession number NITE P-02647).

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