JP4947560B2 - Method for producing dried natto food - Google Patents

Description

  The present invention relates to a method for producing a powdered or flaky dried natto food and a dried natto food produced by the production method.

  Traditionally, soybeans, the raw material of natto, are also called field meat and are characterized by rich protein content, but at the same time other important nutrients such as carbohydrates, dietary fiber, and lipids are contained in a well-balanced manner. It is a nutritional food.

  Considering the improvement in functionality of the protein abundantly contained in soybeans, when protein is absorbed into the body as a nutritional component, it is broken down in the stomach and intestines to become amino acids, and then from the microvilli on the small intestine wall. Absorbed. Therefore, if the decomposition (release) into amino acids constituting the protein is promoted, the food is further excellent in absorbability.

  Some of these various free amino acids have been reported to have specific functionalities such as blood pressure lowering effect of γ-aminobutyric acid (GABA) and fatigue recovery effect of ornithine. It is approved as a health food or is used in health foods such as supplements.

  In recent years, functional components such as soybean isoflavones have attracted attention. It has been reported that soy isoflavone works like the female hormone estrogen and is effective in alleviating osteoporosis and menopause.

  It is known that soybean isoflavones contained in soybean contain 12 kinds of glycosides including genistein, daidzein, glycitein, soy isoflavone aglycone, genistin, daidzin, and glycitin. Most soybeans exist as glycosides, but the glycosides are absorbed into the body from the intestinal tract after sugars are cut off by intestinal bacteria and converted into aglycones. It has been reported that the absorption into the body is excellent by ingesting it in the form of aglycone rather than as a glycoside.

  By the way, soybean is known for various functions as described above, and natto is a representative food processed from the soybean. Natto is fermented by the action of natto bacteria using soybean as a raw material. Recently, attention has been paid to the intestinal regulating action of natto, and it is widely recognized as a food that is socially healthy.

  The present applicant has also proposed a natto food that has been dried after it has been fermented by fermenting and fermenting natto bacteria in the form of powder or flakes (see Patent Document 1).

JP 2004-65032 A

  This powdered or flaky dried natto food has almost no odor like ordinary natto and has high nutritional value and storage stability, but also contains free amino acids and soy isoflavone aglycone as described above. Further increased dry natto food is desired.

  The present invention has been made in view of the background art described above, and it is an object to provide a method for producing a dried natto food having an increased content of free amino acids and soybean isoflavone aglycone, and a dried natto food produced by the production method. And

  In order to solve the above-mentioned problems, the method for producing a dried natto food according to the present invention comprises making soybeans into a powder or flake form, fermenting natto bacteria and lactic acid bacteria in a complex manner, and then drying them. Features. According to this, a dried natto food with an increased content of free amino acids and soybean isoflavone aglycone can be produced.

  When fermenting natto bacteria and lactic acid bacteria in a complex manner, for example, natto bacteria may be inoculated and fermented, and then lactic acid bacteria may be inoculated and fermented, or natto and lactic acid bacteria may be inoculated and fermented at the same time. In short, natto and lactic acid bacteria may be combined and sequentially fermented sequentially or simultaneously.

  As lactic acid bacteria, Lactobacillus brevis, Lactococcus lactis subsp. Lactis, or Lactobacillus acidophilus is particularly preferably used. According to these lactic acid bacteria, the concentration of γ-aminobutyric acid (GABA) contained in the present dried natto food can be further increased, and the amount of conversion to soybean isoflavone aglycone can be further increased.

  The lactic acid bacteria may be rapidly frozen with liquid nitrogen. According to this, it becomes easy to preserve | save lactic acid bacteria, and it can use for manufacture of dry natto food suitably.

  Moreover, when fermenting, it is preferable to ferment for a certain period at normal temperature, and then to ferment for a certain period at a lower temperature. The normal temperature is, for example, in the range of 30 ° C. to 40 ° C., more preferably about 35 ° C. The low temperature is in the range of 1 ° C to 10 ° C, more preferably about 4 ° C. Moreover, the fixed period of normal temperature is 3 to 5 days, for example, More preferably, it is about 4 days. The low temperature constant period is, for example, 5 to 7 days, more preferably about 6 days. According to this, compared with normal fermentation, while the density | concentration of (gamma) -aminobutyric acid (GABA) contained in dry natto food can be made high, the conversion amount to soybean isoflavone aglycone can be increased.

  Moreover, it is preferable to make water content 60 to 65% when fermentation is started. According to this, drying after fermentation can be performed efficiently.

  Moreover, when making it dry after making it ferment, it is preferable to make it dry until it becomes 10% or less of water | moisture content with a warm air of 40 to 80 degreeC. In this case, the efficiency of air drying is low at 40 ° C. or lower, and decomposition is likely to occur at 80 ° C. or higher. Therefore, drying is performed with hot air in the range of 40 ° C. to 80 ° C., more preferably 40 ° C. to 50 ° C. Moreover, in order to stop the decomposition | disassembly of soybean by drying and to replace a spore and to increase the density of a spore, the water | moisture content shall be 10% or less, More preferably, it is 5% or less.

  In addition, it is convenient to use a warm air dryer for drying, but without using a warm air dryer, the air may be separately heated and blown as warm air and dried by other means. Also good. In addition, it is preferable that the warm air at the time of drying is as uniform as possible from the viewpoint of uniform drying.

  According to the present invention, since natto and lactic acid bacteria are planted in a complex manner and fermented, various free amino acids such as γ-aminobutyric acid (GABA) are contained abundantly, and the raw material soybean contains only a small amount. It can be rich in soy isoflavone aglycone. For this reason, dried natto food as an excellent nutritional food can be produced by enhancing these functional components derived from soybeans that are excellent in absorbability to the human body.

  Moreover, since it is dried after being fermented, the ammonia odor peculiar to natto is reduced, and it is also suitable for storage.

  Furthermore, because it is in the form of powder or flakes, it can be put into various dishes and beverages, and it is possible to easily ingest functional components such as free amino acids and soy isoflavone aglycone, as well as many natto bacteria. Because of the inclusion, it can be expected to have an intestinal function.

Graph on extraction amount of amino acids extracted from powdered natto (conventional product) with water Graph of γ-aminobutyric acid (GABA) concentration in each lactic acid bacteria culture Graph on the amount of free amino acids extracted from this dried natto food treated with raw soybean powder, powdered natto (conventional product), and lactic acid bacteria (13951)

  Examples of the present invention will be described with reference to FIGS. 1 to 3 and Tables 1 to 6. FIG.

<Search for lactic acid bacteria suitable for the production of dry natto food>
Natto is planted on soybeans processed into powder or flakes, fermented by holding for 15 to 20 hours in an atmosphere of 40 ° C to 50 ° C and humidity of 60% to 85%, and then fermented in an aerobic environment. Powdered natto with a moisture content of 10% or less is used as a raw material.

  This powdered natto was extracted with water (50 ml of distilled water per gram for 10 minutes) and the amino acid composition of the extract was measured. As a result, as shown in FIG. 1, a significant amount of glutamic acid (Glu) was found compared to other amino acids. Was detected.

Therefore, a search was conducted for lactic acid bacteria that efficiently produce γ-aminobutyric acid (GABA) by the action of glutamic acid decarboxylase (GAD) using glutamic acid (Glu) as a raw material. For the lactic acid bacteria, the strains (circle numbers 1 to 8) shown in Table 1 (list of lactic acid bacteria to be tested) were used.

For culturing lactic acid bacteria, either medium A or B for lactic acid bacteria shown in Table 2 (Lactic acid bacteria medium composition g / 100 ml) was used.

  Add 1 g of powdered natto to 100 ml of liquid medium A for lactic acid bacteria, inoculate each lactic acid strain, incubate at 30 ° C for 3 days, and then double the culture supernatant with citrate buffer for amino acid analysis. After dilution, amino acid analysis was performed and the content of γ-aminobutyric acid (GABA) was measured.

  Then, as shown in FIG. 2, γ-aminobutyric acid in the culture solution added with Lactobacillus brevis (NBRC12005), Lactococcus lactis subsp. Lactis (NBRC12007) and Lactobacillus acidophilus (NBRC 13951) corresponding to lactic acid bacteria 3, 4 and 5 The concentration of GABA was high. After that, we conducted a production test of GABA using powdered natto as a raw material, focusing on these three strains.

  For storage of lactic acid bacteria, the cells cultured in a liquid medium were collected by centrifugation, suspended in a sterilized 15% glycerin solution, rapidly frozen in liquid nitrogen, and stored in a freezer at -75 ° C.

<Production test of γ-aminobutyric acid (GABA) using powdered natto by three lactic acid bacteria strains>
Three types of lactic acid bacteria 3, 4, and 5 used for the production test of γ-aminobutyric acid (GABA) using powdered natto as a raw material were cultured at 30 ° C. for 2 days using the medium A in Table 2 and then centrifuged (7000 rpm, 20 minutes, 4 ° C.), the cells were washed twice with distilled water, suspended in a small amount of distilled water, and then freeze-dried in vacuo. The amount of cells used in the production test of γ-aminobutyric acid (GABA) was freeze-dried lactic acid bacteria powder obtained from 50 ml of the culture solution per 100 g of powdered natto serving as a substrate.

  An example of a production test of γ-aminobutyric acid (GABA) using powdered natto and three types of freeze-dried lactic acid bacteria powders 3, 4, and 5 is shown below.

  Mix 100ml of powdered natto with 150ml tap water in which three kinds of freeze-dried lactic acid bacteria powders 3, 4 and 5 of Lactobacillus brevis (NBRC12005), Lactococcus lactis subsp. Lactis (NBRC12007) and Lactobacillus acidophilus (NBRC13951) are suspended. After fermentation at 35 ° C. for 4 days, fermentation was further performed at 4 ° C. for 6 days. In addition, although fermentation progress is so favorable that there is much water | moisture content at the time of fermentation start, the water | moisture content content at the time of fermentation start was made into about 60 to 65% in consideration of the subsequent drying process.

  The sample after fermentation was dried to a water content of 10% or less with warm air of 40 to 80 ° C., crushed with a blender, and processed into a powder form to obtain a lactic acid bacteria double fermented natto powder. After thoroughly mixing 0.4 g of lactic acid bacteria double fermented natto powder and 10 ml of 8% trichloroacetic acid (TCA) solution, the mixture was shaken at 20 ° C. for 2 hours to extract γ-aminobutyric acid (GABA). Free amino acids in the extract were analyzed with an amino acid analyzer.

As a result of analysis, the production of GABA was observed in any of the three types of lactic acid bacteria tested as shown in Table 3 (TCA-extracted amount of γ-aminobutyric acid (GABA) mg / 100 g). Fermentation at 35 ° C Later, it was found that the concentration of γ-aminobutyric acid (GABA) further increased by leaving it in an environment of 4 ° C. As a result of content of raw soybean of powdered natto and γ-aminobutyric acid (GABA) of powdered natto, it is 0.1mg / 100g or less in raw soybean powder and 24.1mg / 100g in powdered natto By this method, it is possible to produce a significant amount of γ-aminobutyric acid (GABA) by the combined fermentation of natto and lactic acid bacteria without adding any substrate of γ-aminobutyric acid (GABA) other than soybean origin. It turned out to be.

  Furthermore, γ extracted from raw soybean powder, powdered natto, and powder treated by this method (fermented using lactic acid strain NBRC13951, fermented at room temperature of 35 ° C. for 4 days, and further fermented at low temperature of 4 ° C. for 6 days) -The result of having compared the free amino acid containing aminobutyric acid (GABA) was shown in FIG. By treating with this method, free amino acids other than γ-aminobutyric acid (GABA) are also increased, and it is concluded that the processed product is excellent in absorbability of amino acids into the body and has high nutritional value. The same tendency was observed in the other two strains of lactic acid bacteria.

<Measurement of conversion of soy isoflavone to aglycone>
Many isoflavones are known to exist as glycosides in soybean, but the glycoside sugars are cut off during the combined fermentation of natto and lactic acid bacteria using this technology. We examined whether it could be converted into a shape.

  Isoflavones were extracted with 80% methanol from raw soybeans, natto powder, and prototypes fermented under various conditions, and the typical glycosides daidin, glycitin and genistin and their respective aglycones, daidzein, glycitein and genistein were measured. .

As a result, as shown in Table 4 (comparison of soy isoflavone content mg / 100g), the total of three types of isoflavones present as aglycone in the raw soybean was 0.8mg / 100g. Powdered natto fermented with natto bacteria for 20 hours (conventional product) increased to 23.0 mg / 100 g. Furthermore, by this technique, lactic acid bacteria 5 (NBRC13951) was added, and what fermented at 35 degreeC for 4 days and 4 degreeC for 6 days was increased to 121.8 mg / 100g.

  On the other hand, fermentation for 4 days at 35 ° C without addition of lactic acid bacteria increased to 96.6mg / 100g when left at 4 ° C for 6 days, and aglycone tends to increase due to long-time fermentation of natto bacteria. However, when lactic acid bacteria were added, it was confirmed that the amount of conversion to aglycone was large.

  Based on the above results, dried natto with improved absorption of isoflavones into the body, where glycosides are converted to aglycones in the combined fermentation process of natto and lactic acid bacteria using this technology. The food was prototyped.

For reference, the isoflavone content of off-the-shelf products marketed as dry natto is shown in Table 5 (comparison mg / 100g of isoflavone content of commercially available dry natto). Much less than the prototype.

<Behavior of natto and lactic acid bacteria>
Powdered natto before complex fermentation with lactic acid bacteria (when using NBRC13951), prototype of complex fermentation process, natto bacteria and lactic acid bacteria of prototype after drying were measured.

  As a result, as shown in Table 6 (transitions in the number of natto and lactic acid bacteria), natto bacteria are hydrated in a dry powder state or in a complex fermentation with lactic acid bacteria. The number of lactic acid bacteria was 108 or more per gram in the fermentation process, but it was not detected when dried to form a powder.

Therefore, it is considered that the lactic acid bacteria have been killed by the drying method performed in this trial production. If lyophilization is performed, the probiotic effect of lactic acid bacteria as live bacteria can also be expected.

<Analysis method>
The above amino acids were analyzed by a conventional method using a JLC-500 / V2 type fully automatic amino acid analyzer manufactured by JEOL Ltd.

Moreover, the analysis conditions of soybean isoflavone are as follows.
・ Column: HIKARISIL-C-18 (4.6mmID × 250mm)
-Mobile phase: MeOH / H2O (30% / 70%) → MeOH / H2O (70% / 30%) (linear gradient over 40 minutes from the start)
・ Column temperature: 40 ℃
・ Flow rate: 1.0ml / min
・ Detection: UV 254nm

Claims (11)

A method for producing dry natto food,
Soy bean powder or flakes, fermented with natto and lactic acid bacteria combined and fermented, then dried ,
The lactic acid bacterium is either Lactobacillus brevis, Lactococcus lactis subsp. Lactis, or Lactobacillus acidophilus,
In the fermentation, after fermentation for 3 days to 5 days in a temperature range of 30 ° C. to 40 ° C., further fermentation for 5 to 7 days in a temperature range of 1 ° C. to 10 ° C.,
A method for producing a dried natto food characterized by the above . The method for producing a dried natto food according to claim 1, wherein the complexing and fermenting of natto and lactic acid bacteria is performed by planting and fermenting natto bacteria and then fermenting and fermenting lactic acid bacteria.   The method for producing a dried natto food according to claim 1 or 2, wherein the lactic acid bacteria are rapidly frozen with liquid nitrogen. The method for producing a dried natto food according to any one of claims 1 to 3 , wherein the water content at the start of fermentation is 60% to 65%. The method for producing a dried natto food according to any one of claims 1 to 4 , wherein the dried natto food is dried with warm air of 40 ° C to 80 ° C until the water content becomes 10% or less when dried after fermentation. The dried natto food manufactured by the manufacturing method in any one of Claims 1-5 . A method for enhancing γ-aminobutyric acid and soy isoflavone aglycone in dry natto food,
Soy bean powder or flakes, fermented with natto and lactic acid bacteria combined and fermented, then dried,
The lactic acid bacterium is Lactobacillus brevis, Lactococcus lactis subsp. Lactis, or Lactobacillus acidophilus,
In the fermentation, after fermentation for 3 days to 5 days in a temperature range of 30 ° C. to 40 ° C., further fermentation for 5 to 7 days in a temperature range of 1 ° C. to 10 ° C.,
A method for enhancing γ-aminobutyric acid and soybean isoflavone aglycone in dried natto food. The enhancement method according to claim 7, wherein the planting and fermenting the natto and lactic acid bacteria in a combined manner is to inoculate and ferment the lactic acid bacteria after planting and fermenting the natto bacteria. The enhancement method according to claim 7 or 8, wherein the lactic acid bacteria are rapidly frozen with liquid nitrogen. The enhancement method according to any one of claims 7 to 9, wherein the water content at the start of fermentation is 60% to 65%. The enhancement method according to any one of claims 7 to 10, wherein when drying after fermentation, drying is performed with warm air of 40 ° C to 80 ° C until the water content becomes 10% or less.