JPH01157353A - Natto manufacturing method - Google Patents

Abstract

PURPOSE:To prepare a NATTO (fermented soybean) having rich taste and flavor and suppressed water-content, by using a water-resistant sheet having high air and moisture-permeability, e.g., rayon paper, as a packaging material, filling and sealing steamed soybean in the material and subjecting the soybean to fermentation process. CONSTITUTION:A bag 1 made of a water-resistant sheet having high air- and moisture-permeability (e.g., rayon paper) is used as a NATTO fermentation vessel in place of the conventional PSP vessel. During the growing stage of Bacillus natto, a sufficient moisture is supplied even from the outside of the vessel to control the rise of the temperature caused by the invigoration of the fermentation of Bacillus natto. The moisture-removal is effectively performed in the latter stage of fermentation. The water-content of the NATTO can be suppressed to a low level by this treatment to enable the preparation of NATTO having bloom firmly attached to the soybean, rich taste and flavor and low tackiness. The NATTO prepared by this process has excellent presevability because of suppressed water-content.

Description

[Detailed description of the invention] [Purpose of the invention] (Industrial application field) The present invention relates to a method for producing natto.

(Prior art) In order to promote the smooth growth of natto bacteria in the hot air circulation type natto fermentation chamber currently used for boat fishing, it is necessary that high humidity conditions act effectively and in the latter half of fermentation. It has been confirmed that evaporation of soybean water by increasing fermentation heat is necessary.

The production of natto using wet wrat can be said to be a method that fulfills this principle.

Currently, PSP (Poly-Styrene Paper) containers are most commonly used as natto fermentation containers placed in fermentation chambers.

This PSP container is convenient for natto production because it is made of material that is lightweight, easy to process, has excellent heat retention in both hot and cold environments, is hygienic, and is relatively durable. In addition, it is very convenient for transportation and handling during the distribution stage, and it has excellent preservability and tableware replacement properties after reaching adulthood, so it will be a great help in expanding natto consumption.
I am dedicating it to you.

However, on the other hand, this PsP container has poor air permeability and moisture permeability, which means that it is difficult for oxygen and moisture to pass through, which is necessary in the natto manufacturing process, and it contains factors that inhibit the normal growth of natto bacteria. .

In other words, although it has excellent heat retention, it cannot control the rise in fermentation heat of natto bacteria, which prevents the evaporation of water (dehumidification in the latter half of fermentation) as the product temperature rises, and condensation due to water condensation can cause natto products to deteriorate. Keep it moist, and it will become sticky due to bacterial lysis, impairing its shelf life.

This is the reason why consumers are dissatisfied with the fact that they cannot obtain the quality and flavor of warat natto.

Note that some conventional PSP containers have thin needle holes in the lid, etc., but not only do they not provide sufficient air permeability and moisture permeability, but the surface of the natto inside is covered with a polyethylene film. In the end, there is no way to solve the above problems.

(Problems to be Solved by the Invention) The present invention was made in light of the above-mentioned conventional circumstances in natto production.・Using a bag made of a highly moisture-permeable and water-resistant sheet, sufficient humidity is supplied from the outside of the container during the growth of natto bacteria, and as fermentation of natto bacteria becomes active, A manufacturing method that controls the rising product temperature and effectively dehumidifies the water from the soybeans during the period of evaporation (in the second half of fermentation) to obtain natto that has low moisture content and has a long shelf life and excellent flavor. was established.

[Structure of the Invention] That is, the method for producing natto according to the present invention is to place steamed soybeans inoculated with natto bacteria into a bag made of a waterproof sheet with high air permeability and moisture permeability.
It is characterized by fermenting the fermented soybeans in a sealed container and fermenting them under high humidity to obtain natto 2.

(Example) An example will be explained below in order of process: (a) Raw soybeans: Chinese soybeans and pesticides (b) Raw material processing: After washing the soybeans, soak them in tap water overnight, and drain them in a stainless steel wire mesh colander. I moved it and drained it for an hour. After that, leave it in a colander and use a pressure cooker (steam pressure 1.3 kg/crn" after reaching pressure 8.
Steam for 1 minute, then simmer over high heat for 15 minutes. The target hardness of steamed soybeans was set to 120 g or less.

(c) Inoculation of Bacillus natto 2 Commercially available natto starter solution (3°9×
10 cells/ml) was adjusted to the order of 3.9 x 10 cells/ml with sterilized water, and this diluted bacterial solution was injected into steamed soybeans to inoculate Bacillus natto.

(d) Natto fermentation container 2 A roll of rayon paper was selected as a water-resistant sheet with high air permeability and moisture permeability, and this was cut and heat-sealed to a size of 1010 x 15 to make a bag (hereinafter referred to as a rayon paper bag). '') using (
Figure 1).

(e) Contains soybeans: 80g of soybeans inoculated with Bacillus natto
was filled from the front of a rayon paper bag and sealed by heat sealing (Figure 2).

(F) Fermentation conditions: The rayon paper bag that had been filled was placed in a stainless steel strainer and placed on a shelf in the natto fermenter.

The temperature inside the tank was consistently set at 40'C, and fermentation was continued for 18 hours with continuous humidification.

(g) Commercialization: After fermentation is complete, wrap the rayon paper bags in appropriate packaging materials, store them in a cool storage room to prevent the intrusion of germs, label them, etc., and ship them one by one.

(Analysis, investigation) Regarding the above manufacturing process, we conducted a comparative experiment with the case using a conventional PSP container (hereinafter referred to as the "control group").
As a result of the investigation, the following Tables 1 (moisture, hardness) and Table 2 were found.
(sensory examination), and the results shown in Figures 4 (room temperature and product temperature within the fermenter) and 5 (humidity within the fermenter) were obtained.

Table-1 Moisture, hardness analysis, and survey results of steamed soybeans, bacteria-inoculated soybeans, and natto Fermentation conditions 40'C 18 hours Humidification 18 hours I
, 5,000F Hoshimoto Moisture was determined by vacuum drying method (standard miso analysis method).

The hardness was determined by measuring the degree of compression with fingers using a clock scale in g, and calculating the average value of 10 values.

Comparing the changes in moisture content in the table, natto from Taimei Ward has the same moisture content as steamed soybeans, or more. On the other hand, the amount of natto produced by the method of the present invention is approximately % less than this. This difference becomes even larger because the inoculation of Bacillus natto liquid increases the moisture content of the steamed soybeans by about 3%.

The following was derived from the results of this analysis.

In other words, the moisture content of natto in the control group using a PSP container and polyethylene film was 6% under -H40'C continuous humidification conditions.
However, the moisture content of natto according to the present invention using a rayon paper bag was 59% under continuous humidification at -40°C.
．． At 6%, natto 2 with considerably less moisture than the former was obtained.

This is due to the breathability and moisture permeability properties of rayon paper.
During the breeding period of Bacillus natto, sufficient oxygen and humidity close to saturation have the effect of promoting the growth of Bacillus natto, and when the activity of Bacillus natto becomes active and fermentation heat is generated, the moisture content of soybeans reaches U. This is thought to be due to the effect of preventing heat accumulation by evaporating heat.

Next, under the fermentation conditions of -kan 40'C1 continuous humidification for 18 hours in the above example, the sensory characteristics of the control natto and the natto produced by the method of the present invention are compared as shown in Table 2. .

In the natto in this control group, the white grains have become transparent, and the surface of the natto is shiny due to condensed water, and in this state, the inside is also seen to be flattened. Therefore, they are overripe, their stringiness is weakened, and they start to smell like ammonia.

On the other hand, the natto produced by the method of the present invention was aged a little younger, but the condition of the grains and the soybeans were firmer, and the situation was similar to that of the natto. Since the natto flavor was also good, it is thought that if the fermentation time was set a little longer, the texture and flavor would increase.

Next, the progress of the room temperature in the fermenter, the temperature of the fermented soybean product, and the humidity in the tank during the fermentation period was compared and measured using a recorder, and the results shown in Figures 4 and 5 were obtained.

In other words, Fig. 4 shows the room temperature inside the fermenter and the progress of product temperature in the case of 18-hour fermentation with continuous humidity of 40'C1.The room temperature was set at 40'C, but when humidified with a heating steam generator, it rose to 42'C. It rises to about C. In the case of fermentation, the temperature of the product starts to rise around 7 hours after the start of fermentation, as shown by the progress of E.
It shows a peak of 52'C around 15 hours and then decreases. On the other hand, in the method of the present invention, the temperature is shown as progressing to , which is approximately the same as that at room temperature W.

Further, FIG. 5 shows the progress of humidity in the fermenter in the case of 18-hour fermentation with consistent 40C5 continuous humidification.

In other words, it turns on and off about 3 times an hour, and the temperature is 95-10.
High humidity in the 0% RH range is disappointing.

In order to obtain the optimum fermentation conditions in the method of the present invention, the present inventor also conducted experiments using condition settings other than those in the above-mentioned examples.

In other words, the temperature inside the fermenter was set at 30'C, 40C, 50°C, and the maximum room temperature was 50C1i: a chevron-shaped temperature progression, etc., but the room temperature was artificially lowered to 50"C, whether it was a -tan or a chevron. If the temperature is raised, the fermentation of natto bacteria will not take place normally, resulting in insufficient adhesion of whitebait and unripened soybeans, resulting in natto that does not have a natto odor, has a green taste, and has an unpleasant flavor that is not refreshing. There was a tendency to do so.

In the end, it was confirmed that the temperature setting of 40° C. to 45° C. in this example was the most desirable condition in terms of the tendency for room temperature and product temperature to be synchronized and the ease of product temperature control.

In the case of this embodiment, a heating type steam generator is used to replenish moisture, so if the room temperature is set to 40°C, the above-mentioned optimum conditions can be obtained.

Regarding humidity conditions, high humidity conditions close to 100% RH are effective in order to promote the smooth growth of Bacillus natto; humidity below 80% will cause undesirable results such as drying of natto. In relation to temperature, a humidity close to 100% RH was obtained at a room temperature of around 40°C;
It was found that when the room temperature was raised to 50C, the RH only reached about 70%.

[Results of the invention] As described above, the method of the present invention uses an air-permeable and moisture-permeable water-resistant sheet as a packaging material, fills it with steamed soybeans and seals it, and then puts it in the fermentation process. By setting the temperature consistently, and then continuously filling the fermentation with warm humidity throughout the fermentation period and dehumidifying it in the latter half of the fermentation, the moisture content of natto can be kept to a minimum, and this will ensure that the soybeans have a firm whitebait. It is possible to produce flavorful natto with less bite and stickiness.

By suppressing the moisture content, natto can be provided with excellent shelf life.

[Brief explanation of the drawing]

Figure 1 is a perspective view of a bag made of rayon paper used in the method of the present invention, Figure 2 is a perspective view of the same bag filled with steamed natto and sealed, and Figure 3 is a bag opened after fermentation. 4 is a graph showing the progress of the room temperature in the fermenter and the temperature of the fermented natto product during the fermentation process; FIG. 5 is a graph showing the progress of the humidity in the fermenter. 1--Bag body made of water-resistant sheet with high breathability and moisture permeability, 2
-m-Natto.

Claims (1)

[Scope of Claims] 1) Natto production characterized in that steamed soybeans inoculated with natto bacteria are sealed in a bag made of a waterproof sheet with high air permeability and moisture permeability, and fermented under high humidity. Law. 2) The natto manufacturing method according to claim 1, wherein the material of the bag made of a waterproof sheet is rayon paper.