JPH088839B2 - Natto manufacturing method - Google Patents

Description

TECHNICAL FIELD The present invention relates to a method for producing natto using Konbu extract, which has an action of promoting the growth of natto bacteria and an action of improving the quality of natto.

[Conventional technology]

It has been conventionally known that natto is a highly nutritious food containing a good amount of high-quality protein and a good balance of carbohydrates, lipids, minerals, vitamins and the like. In addition, recent studies have confirmed the presence of thrombolytic enzymes in natto, which has increased interest in natto. Natto, which is such an excellent food, is industrially produced as follows. That is, soybeans soaked in water are steamed, a spore suspension of Bacillus natto is sprayed and stirred, and this is weighed in a polystyrene foam container. Then, the opening of the container is covered with a polystyrene film having holes, and after fermenting at about 40 ° C. for about 20 hours, 10
It is produced by aging at 1-2 ° C for 1-2 days. Recently, various methods have been devised to further enhance the taste of natto. As such, for example, a method (Japanese Patent Application Laid-Open No. 55-58079) is disclosed in which konbu-dashi soup is used to impart umami to the natto itself with its tasting component (such as glutamic acid).

[Problems to be Solved by the Invention]

However, in the above-mentioned manufacturing method, natto is produced by mixing natto bacterium in the kombushi soup and spraying it directly onto steamed soybeans. It is difficult to do and the fermentation becomes uneven. Therefore, the upper limit of the spray amount is set up to 1% by weight with respect to the steamed soybeans, but with this amount of spray amount, the advantage of using Kombushi soup does not occur. That is,
The above method is intended to improve the taste of natto with the taste of kombu soup, and the kombu soup soup used is simply the same as when making soup stock for cooking using the taste of kombu soup. It has a low concentration just boiled in water (concentration of Brix near 1 on refractometer). Therefore, although the konbu taste can be imparted to the natto to some extent by the above-mentioned spraying, it is not possible to achieve a substantial improvement in the umami taste over that of the konbu itself or an improvement in the nutritional value.

The present invention has been made in view of such circumstances, and is capable of promoting the growth of natto bacteria to realize a shortened production period and capable of producing natto which is extremely excellent in quality such as flavor and nutritional value. The purpose is to provide a manufacturing method of.

[Means for solving the problem]

In order to achieve the above object, the present invention, a step of immersing soybeans in water, a step of steaming the soybeans soaked, a step of inoculating the steamed soybeans with Natto, and a step of fermenting the soybeans And a step of aging the fermented soybeans, and a method for producing natto in which the soybean soaking solution containing konbu extract obtained by extracting konbu in an acidic aqueous solution having a pH of 2.0 to 6.5 is included. 1)), the step of steaming soybeans soaked in water, the step of inoculating the steamed soybeans with Bacillus natto, the step of fermenting the soybeans, and the step of aging the fermented soybeans, The above natto fungus
A second aspect (second invention) is a method for producing natto, which is inoculated in addition to the steamed soybeans together with the kelp extract extracted and concentrated in an acidic aqueous solution of pH 2.0 to 6.5.

[Action]

The present inventors have conducted a series of studies for the purpose of shortening the manufacturing period of natto and significantly improving the appearance and nutritional value of natto itself. In the course of this research, it was found that the Konbu extract obtained by extracting Konbu in the acidic aqueous solution in the above-mentioned specific acidic region has an action of remarkably promoting the growth of Bacillus natto. That is, if the kumbu extract extracted in this specific acidic region is added to the soybean immersion liquid instead of being sprayed on steamed soybeans, the growth of Bacillus natto will be significantly promoted, The activity of the protease produced by is also dramatically increased. As a result, soybean protein is often decomposed into taste components such as amino acids, so that not only the effect of adding the konbu flavor associated with the addition of konbu extract but also the high quality natto with the original taste and nutritive value of natto are significantly improved. Can be manufactured in a short period of time. Furthermore, since Konbu extract is used instead of Konbu soup, which has a high water content, the amount added can be increased, and uneven fermentation due to spraying a large amount does not occur, resulting in a thick pellicle and gloss. It was found that natto of high quality and high tenacity can be obtained in a short period of time, and the present invention has been reached together with the above findings. The concentrated Konbu extract in the second aspect of the present invention has a concentration of Brix in the range of 3.0 to 20 as measured by a refractometer. Further, it is particularly preferable to use, as the above-mentioned Konbu extract, an extract obtained by extracting Konbu in a specific acidic region and subjecting the extract to an activated carbon treatment, an ultrafiltration treatment, or both treatments. That is, the konbu extract extracted in a specific acidic region is subjected to the above-mentioned treatment, and more natto growth factors are extracted, and the concentration of konbu extract is further concentrated. It also promotes the appearance and quality of natto itself. Then, the above-mentioned treatment removes the unpleasant taste component of kelp which is present in the relatively high molecular weight fraction (with the scent and color peculiar to kelp), and the effect of further improving the flavor can be obtained. .

 Next, the present invention will be described in detail.

The konbu used in the present invention refers to those belonging to the genus Konbu among brown algae, such as true konbu, Rishiri konbu, Rausu konbu, Mitsuishi konbu, long konbu, Atsuba konbu, kagome konbu, hosome konbu, and Tororo konbu etc. No matter what kind of kelp it is, its place of origin and grade are not limited.

The kelp extract of the present invention is kelp extracted in a specific acidic region of pH 2.0 to 6.5. This extraction is performed as follows, for example, and is used in the first invention in this case. That is, konbu extract (hereinafter referred to as "konbu extract 1") is obtained by immersing konbu in an acidic aqueous solution of pH 2.0 to 6.5 and performing extraction under conditions of an extraction temperature of 80 to 95 ° C and an extraction time of 2 to 30 minutes. can get. This Konbu extract 1 may be used as it is, or one obtained by subjecting it to one or both of an activated carbon treatment and an ultrafiltration treatment (hereinafter referred to as “Konbu extract 2”) may be used. By extracting Konbu using an aqueous solution whose pH is adjusted to an acidic range in this way, it becomes easier to extract the Bacillus subtilis natto growth factor (for example, mineral components) in Konbu, and at the same time, in the neutral and alkaline ranges. Extraction of polysaccharides such as alginic acid and unpleasant taste components which are dissolved in water and thereby extracted in water is eliminated, and a good extract can be obtained. Further, the above-mentioned extract is further subjected to an activated carbon treatment and an ultrafiltration treatment, whereby the unpleasant taste component of kelp present in a relatively high molecular weight fraction (the scent and color peculiar to kelp are accompanied)
Are removed. As a result, when the above-mentioned acidic extraction alone is used and an extract without activated carbon treatment or ultrafiltration treatment is used, inconvenience may occur in some cases (browning of the color of natto itself due to high molecular fraction components, dullness) ， The smell of scent)
Will be almost completely eliminated. Such an acidic extract may be used as it is or may be used after being neutralized.

The extraction of Konbu extract 1 will be described in more detail. The pH adjustment of the extraction aqueous solution is not particularly limited, but it may be adjusted using organic acids such as acetic acid and citric acid alone or in combination. The acidity is usually set to pH 2.0-6.5. More preferred is pH 4.5-
It is in the range of 5.0. That is, if the pH is lower than 2.0, the extraction efficiency will be poor and the growth of Bacillus natto will be adversely affected, and if the pH is higher than 6.5, the elution state of the Bacillus natto growth factor from kelp will be deteriorated. . The extraction temperature is usually 80 to 95 ° C, and the extraction time is 2 to
It is set to 60 minutes, preferably 10 to 30 minutes. That is, when the extraction temperature falls below 80 ° C, the extraction efficiency decreases, and conversely, 95%.
When it exceeds ℃, the unpleasant taste components of Konbu elute more.
Also, if the extraction required time is less than 2 minutes, the extraction efficiency will be reduced, and if it is more than 60 minutes, the unpleasant taste components will be eluted more. Such extraction is carried out using 1 to 10 parts by weight of dried konbu (collected and dried in the sun and usually containing 14 to 17% by weight of water) (hereinafter abbreviated as "part"). It is carried out by immersing in 30 parts of an acidic aqueous solution at the temperature and for the above time. The extraction concentration of Konbu extract in the thus obtained extract is usually Brix of 0.5 to 3.0 based on the measurement by a refractometer.

The above-mentioned Konbu extract 2 is obtained by subjecting the above-mentioned Konbu extract 1 to one or both of activated carbon treatment and ultrafiltration treatment. In this case, it is preferable to use activated carbon having an average pore size of 10 to 30 Å, more preferably 20 to 30 Å, as the activated carbon used for the activated carbon treatment. The activated carbon treatment is carried out by adding the activated carbon to 50 to 90
It is preferable to contact at 20 ° C. for 20 to 40 minutes. The ultrafiltration treatment is usually performed on the extract or untreated extract that has been treated with the activated carbon, and is performed using a membrane having a molecular weight cutoff of 200,000 or less. As a result, the high molecular weight fraction components are surely removed, and Konbu extract 2 free from unpleasant taste components is obtained.

Next, the method for producing natto using the above-mentioned Konbu extract 1 or Konbu extract 2 (first invention of the present case) will be specifically described. First, soybeans are dipped in a water dipping solution containing Konbu extract. In this case, the Konbu extract is usually contained by mixing the Konbu extract with an aqueous solution, and the content thereof is set within the range of 0.1 to 30%. More preferably, it is within the range of 2.0 to 15%. Next, the soaked soybeans are steamed, and the steamed soybeans are inoculated with Bacillus natto. Inoculation of Bacillus natto is usually carried out by inoculating 1 kg of steamed soybeans with a spore suspension so that the number of Bacillus natto is in the range of 10 ⁴ to 10 ⁹ . More preferred is the range of 10 ⁶ to 10 ⁷ . Then, after inoculation, the fermentation temperature of 35 to 42 ℃, preferably 40 ℃ 15 ~
Fermented for 25 hours, preferably 18 hours, then 0-15 ° C,
It is preferably refrigerated at 10 ° C. for 24 to 48 hours for aging. This makes it possible to obtain the desired natto.

In the above manufacturing method, soybeans are soaked in a water dipping solution containing Konbu extract in advance, but soybeans may be first soaked in water and then Konbu extract may be added and contained therein.

Next, the second invention of the present case using the concentrated Konbu extract will be specifically described. Here, the concentrated Konbu extract is preferably Brix 3.0 to 20. When Brix exceeds 20, it has a growth effect on Bacillus natto, but the state becomes unsuitable for spraying due to increase in viscosity and crystallization. The concentrated kelp extract can be obtained by concentrating the kelp extract obtained by extracting the kelp extract in the specific acidic region by, for example, vacuum concentration, membrane concentration, or the like. A concentrate of 2 is preferable. That is, the second
In the invention, first, 3 to 4 parts of water is added to 1 part of soybean to immerse the soybean, and this is steamed. Next, this steamed soybean is inoculated with a spore suspension of Bacillus natto mixed with the concentrated Konbu extract as in the above-mentioned production method. in this case,
A spore suspension of 10 ⁸ to 10 ⁹ bacteria / ml of Bacillus natto is diluted with the concentrated Konbu extract to 10 ⁶ to 10 ⁷ bacteria / ml. Then, the target natto is obtained by fermenting and aging the inoculated product at the above temperature and time.

〔The invention's effect〕

As described above, the method for producing natto of the present invention uses a kelp extract obtained by extracting kelp in a specific acidic region. That is, according to the first method of the present invention, since the above-mentioned Konbu extract is added to the soybean soaking solution for inclusion, the amount of Konbu extract can be increased and the growth of Bacillus natto is significantly promoted. As a result, high quality natto with a thick pellicle, good gloss and strong stickiness can be obtained in a short time. In the second method of the present invention, the Bacillus natto is inoculated together with the concentrated Konbu extract into steamed soybeans, so that the concentrated Konbu extract significantly increases the activity of the protease that promotes the growth of Bacillus natto. To be enhanced.
As a result, soybean protein is often decomposed into tasting components such as amino acids, so that the obtained natto becomes a highly nutritious food with a high umami that cannot be reached only by the umami of konbu extract itself. . Further, by using such a concentrated Konbu extract, it becomes possible to shorten the production period of natto. In particular, as the above Konbu extract,
When kelp is extracted in a specific acidic region and further treated with activated carbon and ultrafiltration, the natto growth factor is further concentrated and the unpleasant taste component of kelp present in a relatively high molecular fraction (specific to konbu) Aroma and color are removed), the production period of natto can be shortened and the quality of natto can be improved, and the effect of improving flavor can be obtained.

 Next, examples will be described together with comparative examples.

[Example 1] 2 l of water was adjusted to pH 4.0 with acetic acid, and 150 ml of water was added to this water.
Add g and raise the total temperature to 95 ° C, at which temperature 1
Extraction was performed for 0 minutes. The extraction concentration of this Konbu extract was Brix 2.8 with a refractometer (hereinafter this Konbu extract is referred to as "Konbu extract 1"). Bacillus subtilis natto was cultured in a spidiene medium (SM medium) containing 1% of the obtained Konbu extract 1 at 37 ° C. with shaking, and 12 hours later, the absorbance was measured at a wavelength of 660 nm. Higher absorbance indicates that the Bacillus natto is growing (turbidity is caused by the growth of the bacterium).

[Examples 2 to 6] The above-mentioned Konbu extract 1 was roughly filtered using a filter cloth, and then activated carbon (Shirasagi New Gold, manufactured by Takeda Pharmaceutical Co., Ltd.) was added to the filtered solution in an amount of 0.3% relative to the above-mentioned Konbu extract 1. It was
Then, this was heated to 60 ° C. and subjected to contact treatment while stirring for 20 minutes. After this reaction, a part of Konbu extract 1 is shown in Table 1 below, and the molecular weight of each fraction is 3000,6000,10000,50000,20.
An ultrafiltration treatment of 0000 was performed. Then, Bacillus subtilis natto was cultivated at 37 ° C. in the SM medium containing 1% of each liquid thus obtained, and 12 hours later, the absorbance was measured at a wavelength of 660 nm.

[Comparative Example 1] 37% of Bacillus natto was added to SM medium containing no kelp extract.
The cells were cultured at ℃, and after 12 hours, the absorbance was measured at a wavelength of 660 nm.

[Comparative Example 2] To water 1, 12 g of true kelp was added, and the whole temperature was set to 80 ° C.
The temperature was raised to 10, and extraction was performed at that temperature for 10 minutes. The extraction concentration of this kombushi soup was Brix 0.6 with a refractometer.
Bacillus subtilis natto was cultivated at 37 ° C. in an SM medium containing 1% of the obtained Konbu-dashi soup, and after 12 hours, absorption was measured at a wavelength of 660 nm.

The results of the absorbance measurement in Examples 1 to 6 and Comparative Examples 1 and 2 are shown in Table 1 below.

From the results shown in Table 1 above, the absorbance of Bacillus natto of Examples 1 to 6 using Konbu extract is 3 times or more the absorbance of Bacillus natto of Comparative Example 1 in which the extract is not added. The absorbance is about 2.4 times that of the Bacillus subtilis natto of Comparative Example 2 using the kombushi soup. From this, it is clear that Konbu extract promotes the growth of Bacillus natto. Further, there is no large difference in absorbance between Example 2 having a molecular weight cutoff of 3000 and Example 6 having a molecular weight cutoff of 200,000, and Example 2 having a molecular weight cutoff of 3000 exhibits a value three times or more that of Comparative Example 1. Therefore, the molecular weight cutoff of 30 contained in all the above-mentioned fractions (Examples 2 to 6)
It can be seen that below 00 contains components that promote the growth of Bacillus natto. Furthermore, it can be seen that Konbu-dashi soup contains almost no components that promote the growth of Bacillus natto.

[Example 7] 60 ml of the Konbu extract 1 of Example 1 was added to 3 l of water. After soaking 1 kg of soybean in this for 18 hours at 10 ° C and steaming, a spore suspension of 10 ⁶ bacteria / ml natto was sprayed per 100 g of steamed soybean and sprayed in a conventional manner (fermented at 40 ° C for 20 hours. After that, 10 ℃
The natto was manufactured according to the method of aging for 48 hours.

[Example 8] The above-mentioned Example 2 was used instead of the Konbu extract 1 of Example 7 above.
60 ml of Kumbu extract having a molecular weight cut off of 3000 or less was contained. Natto was produced in the same manner as in Example 7 except above.

[Example 9] The above-mentioned Example 3 was used instead of the Konbu extract 1 of Example 7.
60 ml of Kumbu extract having a molecular weight cut off of 6000 or less was contained. Natto was produced in the same manner as in Example 7 except above.

[Example 10] The above-mentioned Example 4 was used instead of the Konbu extract 1 of Example 7 above.
60 ml of Kumbu extract having a molecular weight cut-off of 10,000 or less was contained. Natto was produced in the same manner as in Example 7 except above.

[Example 11] The above-mentioned Example 5 was used in place of the Konbu extract 1 of Example 7 above.
60 ml of Kumbu extract having a molecular weight cut off of 50,000 or less was contained. Natto was produced in the same manner as in Example 7 except above.

[Example 12] The above-mentioned Example 6 was used in place of the Konbu extract 1 of Example 7 above.
60 ml of Kumbu extract having a molecular weight cut off of 200,000 or less was contained. Natto was produced in the same manner as in Example 7 except above.

[Comparative Example 3] 1 kg of soybean was immersed in 3 liters of water at 10 ° C for 18 hours, and the soybean was steamed. Then, a spore suspension of 10 ⁸ bacteria / ml of Bacillus natto was sterilized with water.
It was diluted 100-fold, and 10 ⁶ natto fungus spores were sprayed per 100 g of the steamed soybeans, and natto was manufactured according to a conventional method.

The natto obtained from each of Examples 7 to 12 and Comparative Example 3 was treated by 20 professional panelists on the 3rd day after completion of fermentation.
A sensory test was carried out in a 5-level evaluation based on the quality standards shown below, and the average value is shown in Table 2 below.

<Appearance> 5 ... A glossy white uniform coating of milky white pellicle.

4 ... Milky white pellicle is slightly sparse and glossy.

3 ... Light brown pellicle evenly covered and glossy.

2. A light brown pellicle that is evenly coated and has no gloss.

1 ... Brown pellicle is sparse and has no gloss.

<Aroma> 5 ... Aroma rich in natto with no ammonia odor.

4 ... It has no ammonia odor and has a natto-like aroma.

3 ... A little odor of ammonia, but with an aroma similar to natto.

2 ... An odor of ammonia, with little aroma like natto.

1 ... Ammonia smell is strong, and there is no natto-like aroma.

<Thin pulling> 5 ... A substance with a large amount of mucilage and high elasticity.

4-Much sticky material and strong elasticity.

3 ... Slightly less viscous material and slightly less elastic.

2 ... Slightly elastic with little sticky material.

1 ... A little sticky substance and weak elasticity.

<Umami> 5 ... Very strong.

4 ... strong.

3 ... Normal.

2 ... weak.

1 ... very weak.

<Hardness> 5 ... Hard.

4 ... A little hard.

3 ... Normal.

2 ... a little soft.

1 ... It's soft.

<Comprehensive evaluation> 5 ... Good.

4… Somewhat good.

3 ... Normal.

2 ... Slightly bad.

1 ... bad.

From the results shown in Table 2 above, it was evaluated that the natto of Examples 7 to 12 using Konbu extract was preferable in all respects to the natto of Comparative Example 3. In particular, the appearance of pellicle thickness,
It was evaluated to be excellent in terms of stringiness and umami.

Example 13 1 kg of soybean was soaked in 3 liters of water at 10 ° C. for 18 hours, and the soybean was steamed, and then a spore suspension of 10 ⁸ bacteria / ml of Bacillus natto was obtained in Example 1 above. Concentrate Konbu Extract 1 under reduced pressure and Brix 8.
Dilute 100 times with 0 concentrated and steam 100% soybeans
The natto was manufactured according to a conventional method by spraying 10 ⁶ bacteria / ml.

[Comparative Example 4] 1 kg of soybean was immersed in 3 liters of water at 10 ° C for 18 hours, and the soybean was cooked, and then a spore suspension of 10 ⁸ bacteria / ml of Natto was obtained from Comparative Example 2 above. It was diluted 100 times with soup stock and sprayed with 10 ⁶ bacteria / ml per 100 g of steamed soybean to produce natto according to a conventional method.

Natto obtained from Example 13 and Comparative Examples 3 and 4 above,
On the third day after completion of fermentation, a sensory test was conducted by 20 professional panelists on a 5-point scale based on the above-mentioned quality standards. The results are shown in Table 3 below.

From the results of Table 3 above, it was evaluated that the natto of Example 13 using Konbu Extract 1 was preferable in all respects as compared with the natto of Comparative Examples 3 and 4. In particular, it was evaluated as excellent in appearance such as thickness of pellicle, strength of stringing and umami.

Claims (3)

[Claims] 1. A step of soaking soybeans in water, a step of steaming the soaked soybeans, a step of inoculating the steamed soybeans with Bacillus natto, a step of fermenting the soybeans, and an aging of the fermented soybeans. The method for producing natto, which comprises the step of allowing the soybean soaking solution to contain Konbu extract obtained by extracting Konbu in an acidic aqueous solution having a pH of 2.0 to 6.5. 2. A step of steaming soybean soaked in water, a step of inoculating steamed soybean with Bacillus subtilis natto, a step of fermenting said soybean, and a step of aging said fermented soybean, A method for producing natto, which comprises inoculating natto bacterium with the above-mentioned steamed soybean together with konbu extract concentrated and extracted in an acidic aqueous solution of pH 2.0 to 6.5. 3. The above-mentioned kelp extract has a kelp content of pH 2.0 to 6.5.
The method for producing natto according to claim 1 or 2, wherein the extract is obtained by subjecting the extract to an activated carbon treatment and / or an ultrafiltration treatment.