JPH0337912B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to soy sauce koji, and its purpose is to obtain koji with a high citric acid content. Conventionally, in the production of soy sauce, koji obtained by inoculating and culturing yellow koji mold into koji-making raw materials prepared from soybeans, wheat, rice, etc. is used. During the koji production period, koji mold assimilates the components of the koji raw material, which serves as a culture medium, as a carbon source and nitrogen source, promotes proliferation or energy metabolism, and produces and secretes various enzymes necessary for subsequent fermentation. Various studies have been conducted on the changes in various components in the koji material during the koji making process.
Organic acids have also been reported (Rikou Vol. 42,
No. 1, p. 35-40, 1964). Among organic acids, citric acid is found in large amounts in soybeans, rice, etc.
It is known that in soy sauce koji, it decreases during koji making (for example, the above report or the Japan Brewing Association, ``List of Brewing Components (Sake, Miso, Soybean Oil)'',
Japan Brewing Association, published on December 15, 1962,
(See pages 130-132). The citric acid content in de-koji is
It is involved in the initial PH of moromi, and when the citric acid content is high, the initial PH of moromi decreases, which affects the subsequent fermentation production of alcohol and lactic acid by yeast and lactic acid bacteria. Research has been conducted for a long time on the relationship between Aspergillus oryzae and citric acid production, and Aspergillus oryzae has high citric acid productivity and is used for industrial production of citric acid. The citric acid productivity of Aspergillus oryzae was also investigated.
It is recognized that citric acid can be produced in large amounts depending on the type of koji juice culture. However, there have been no reports that have examined in detail the conditions for producing citric acid in soy sauce koji using Aspergillus oryzae, and in particular, no attempt has been made to accumulate a large amount of citric acid in soy sauce koji. Furthermore, koji production is generally carried out in an open system, and as a result, it is susceptible to contamination by bacteria and other germs, and measures to prevent such contamination are always a problem.
As a measure to prevent bacterial contamination, inorganic acid,
There are methods of incorporating organic acids, antibiotics, bactericides, etc. into the koji raw material. However, these methods still have problems such as adversely affecting the growth of koji mold, impairing product quality, and being unfavorable in terms of food hygiene. The present inventors make koji using yellow koji mold having the ability to produce and accumulate citric acid as seed koji, and prepare soy sauce koji with a citric acid content of 0.8% W/W or more based on dry koji and a pH of 4.7 to 6.5. We have discovered that by doing so, it is possible to reduce the number of bacteria contaminating koji, and that when soy sauce is produced using this koji, alcohol fermentation is promoted and the brewing period can be shortened. Also,
After examining the koji making conditions for obtaining such soy sauce koji, we found that the moisture content of the koji material at the start of koji production (initial moisture content of the koji material) and the koji production temperature conditions were within a certain range, that is, as shown in the attached drawing, Figure 1. The present invention was completed based on the knowledge that it is necessary to set the value within the shaded range shown in FIG. The koji-making raw materials used in the present invention may be those used in the production of soy sauce, and specifically include protein raw materials such as soybeans, defatted soybeans, dehulled soybeans, and gluten, as well as wheat, rice, barley, and naked barley. One or more of carbohydrate raw materials such as , bran, sweet potato starch, potato starch, and cornstarch are used. The types and blending ratio of raw materials are appropriately selected depending on the type of soy sauce product intended. In addition, raw material processing for these koji making raw materials, such as selection,
The method conditions for washing, soaking, sprinkling with water, steaming, boiling, roasting, crushing, etc. also follow the conventional methods. As described later, the citric acid productivity of Aspergillus oryzae is correlated with the initial moisture content of the koji material during koji production and the temperature conditions for koji production. It is necessary to consider various conditions so that the following conditions can be set. The yellow koji mold used in the present invention is a koji mold for soy sauce that has the ability to produce and accumulate citric acid.
Bacterial strains belonging to the genus Tamari etc. may be used. The yellow koji mold in the present invention also includes so-called white koji mold, which is used in light soy sauce. These koji seeds can also be prepared using germinated koji seeds using a conventional method. The koji production method is not particularly limited, and commonly used methods such as the koji cover method and the ventilation koji production method may be applied. The citric acid productivity of Aspergillus oryzae is closely correlated with the initial moisture content of the koji material and the temperature conditions for koji production, as shown in the experimental examples described below. In other words, the lower the initial moisture content of the koji material and the lower the koji making temperature condition, the more citric acid produced and accumulated, and when both low moisture content and low temperature conditions are set at the same time, the production of citric acid is significant. Is recognized. If the initial moisture content of the koji material is low, the amount of citric acid produced will increase, but if it is too low, the growth of koji mold will be insufficient, the growth of hyphae will be poor, and sand koji will easily form. For the growth of Aspergillus oryzae, the initial moisture content of the koji material must be about 30% W/W or more, preferably about 35% W/W or more. On the other hand, if the initial moisture content of the koji material exceeds 55% W/W, the koji becomes muddy, which not only makes the koji making operation difficult, but also makes it susceptible to bacterial contamination. Therefore, the initial water content of the koji material is set in the range of about 30 to 55% W/W depending on the temperature conditions for making koji. Regarding the temperature conditions for making koji, the amount of citric acid produced increases at lower temperatures, and koji can be made even under low temperature conditions of 20°C or less, but if the temperature is too low, the growth of koji mold will be delayed and the production of protease, amylase, etc. will be delayed. The problem is that the time when enzyme production reaches its peak is delayed, making it unsuitable as a condition for making koji. Furthermore, considering that the optimum temperature condition for germination of koji mold spores is 24 to 28°C, it is desirable that the temperature condition for making koji is 20°C or higher. In addition, if the initial moisture content of the koji material is low, citric acid production by Aspergillus oryzae can occur even under relatively high temperature conditions, but if the temperature exceeds 33℃, the koji material dries out and vigorous mycelial growth cannot occur, resulting in the production of citric acid by Aspergillus oryzae. So-called heavy education is hindered. Furthermore, when koji is made under high temperature conditions, the activity of enzymes such as proteases decreases. Therefore, it is desirable that the temperature conditions for making koji be within the range of 20 to 33°C. It is essential that the pH of the soy sauce koji of the present invention is 6.5 or less. When the pH exceeds 6.5, the desired effect of the present invention,
In other words, the effects of reducing the number of contaminating bacteria and promoting alcohol fermentation by yeast cannot be sufficiently achieved. There is a strong relationship between the PH of koji and the amount of citric acid produced.
Citric acid content in terms of dry weight of koji is 0.8%
It was found that if the temperature was W/W or higher, the koji pH would be 6.5 or higher. On the other hand, if the amount of citric acid produced is too large and the koji pH is low, the initial moromi pH will drop, inhibiting the action of enzymes such as protease, which will cause a decrease in the dissolved nitrogen utilization rate of the raw material. It is inappropriate as such. Therefore, the pH of soy sauce koji must be 4.7 to 6.5. In order to produce soy sauce koji with such citric acid content and PH, it is necessary to set the initial moisture content conditions of the koji material and the koji production temperature conditions within the above-mentioned ranges. The suitable initial moisture content conditions for the koji material and the range of the koji production temperature conditions that satisfy these conditions are within the oblique line range shown in FIG. If we express the area within the shaded area in Figure 1 using an inequality, we get
It is as follows. X = Initial moisture content of koji material Y = Koji making temperature 30≦X≦36 -2/3X+46≦Y≦-1/6X+38 36≦X≦39 -2/3X+46≦Y≦-1/13 (9X-740) 39 ≦X≦49 20≦Y≦-1/13 (9X-740) 49≦X≦55 20≦Y≦23 The conditions for producing citric acid will be described below with reference to experimental examples. Experimental Example 1 5 g of defatted soybeans were sprinkled with water at 5 levels of 5 to 9 ml each to absorb water, 5 g of fried cracked wheat was added to these, and 1 kg/kg was added with saturated steam in a 500 ml Erlenmeyer flask with a cotton stopper. cm ² (gauge pressure) for 45 minutes, and after cooling, inoculate with soy sauce koji Aspergillus oryzae F-1124 (Feikoken Bacteria No. 1365).
Each of the koji was placed in a thermostatic chamber adjusted to five temperature conditions ranging from 23 to 33°C, and koji was made for 96 hours to obtain soy sauce koji. The citric acid content in the koji was determined by liquid chromatography of the ground extract of the koji using a carboxylic acid automatic analyzer. The results were as shown in Table 1. The citric acid content in the table is expressed in mg per 10 g of dry matter of the koji material.

[Table] As is clear from Table 1, when the initial moisture content of the koji material is 37% W/W (watering amount 100%), it is below 30℃, 40℃
%W/W (watering amount 120%) is below 28℃, 44%W/W
The citric acid content in koji is below 25℃ for W (watering rate 140%), and below 23℃ for 47% W/W (watering rate 160%) and 50% W/W (watering rate 180%). It is possible to obtain more than 0.8% W/W. Experimental Example 2 After making koji using various initial moisture contents and koji making temperatures in the same manner as in Experimental Example 1, the koji was ground, extracted with deionized water, and the koji PH of the extract was measured using a Hitachi-Horiba PH meter. It was measured. The results of plotting the relationship between koji pH and citric acid content are shown in Figure 2. When producing soy sauce products using the soy sauce koji of the present invention, there are no particular restrictions on the preparation, fermentation, and aging methods and conditions. Fermentation can also be promoted by adding useful microorganisms such as lactic acid bacteria or yeast at an appropriate time, such as at the beginning of preparation. The soy sauce koji of the present invention is a koji with high citric acid content and less bacterial contamination. Furthermore, when brewed using this, alcoholic fermentation by yeast immediately proceeds, shortening the brewing period and making it possible to obtain light-colored soy sauce with excellent flavor. Furthermore, if koji with a particularly high citric acid content is used and fermented and matured, a soy sauce product with a high citric acid content and excellent flavor can be obtained. Similarly, when such koji is digested, a digestive juice with no bitterness and excellent flavor can be obtained. Hereinafter, the present invention will be explained in more detail with reference to Examples and Application Examples. Example 1 20 kg of defatted soybean meal was sprinkled with 20 liters of 70°C boiling water and absorbed, and then steamed for 40 minutes at 1 kg/cm ² (gauge pressure) using saturated steam in a pressure steamer. Then, after cooling rapidly, 20 kg of roasted and cracked wheat was added and mixed well to make a raw material for making koji (moisture content: 36.2
%). 40 g of bran culture of the soy sauce koji mold Aspergillus oryzae F-1124 (Feikoken Bibori No. 1365) was mixed with this as a seed koji, and this
Soy sauce koji made by making koji at ℃ for 48 hours and containing 850g of citric acid.
Obtained 48Kg. Example 2 Sprinkle 500 ml or 750 ml of water on 500 g of defatted soybeans to absorb it, and absorb this at 1 Kg/cm ² (gauge pressure) for 30
After steaming and quenching, add 500g of roasted cracked wheat.
Next, 1 g of Aspergillus oryzae F-1124 bran culture was mixed as a seed koji, which was placed in a koji lid and made into koji at 23°C or 28°C for 84 hours to obtain soy sauce koji. The results of analyzing each koji were as follows.

[Table] Application example 1 10 kg of defatted soybeans was sprinkled with 9 liters of 80°C boiling water and absorbed, then steamed at 120°C for 40 minutes, then 10 kg of roasted cracked wheat was added, stirred and mixed, and allowed to cool. Immediately thereafter, Alpergillus oryzae F-1124 was sprayed and koji was made at 25°C for 3 days to obtain soy sauce koji with a citric acid content (in terms of koji dry matter) of 1.787% W/W. In addition,
The moisture content of the koji material at the start of koji production was 34.5%. This koji was prepared with 43.5 kg of 25% salt solution, and 30
A raw soy sauce with good flavor was obtained by fermenting it at ℃ for 5 months. Analysis of this raw soy sauce revealed that the alcohol content was 1.74%, which was approximately 0.5% higher than the control soy sauce obtained from conventional koji.
In addition, the initial moisture content of koji material for koji made using the conventional method is
The citric acid content at the time of making koji was 0.299%.

[Brief explanation of drawings]

FIG. 1 shows the initial moisture content of the koji material and the range of koji production temperature conditions for obtaining the koji of the present invention.
FIG. 2 is a graph showing the relationship between the citric acid content in koji and the PH of koji.

Claims (1)

[Scope of Claims] 1. Yellow koji mold having the ability to produce and accumulate citric acid is inoculated into a raw material for making koji, and the initial moisture content X of the koji material and the koji making temperature Y are determined as the conditions at the start of koji production using the following inequalities. A soy sauce koji with a citric acid content of 0.8% W/W or more based on the dried koji and a pH of 4.7 to 6.5, which is obtained by culturing under the koji production temperature conditions set within a range of 1. 30≦X≦36 -2/3X+46≦Y≦-1/6X+38 36≦X≦39 -2/3X+46≦Y≦-1/13 (9X-740) 39≦X≦49 20≦Y≦-1/13 (9X−740) 49≦X≦55 20≦Y≦23