JPH0125558B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method for producing solid koji, and its purpose is to obtain solid koji with less bacterial contamination and high enzyme titer such as protease. When producing solid koji, which is conventionally used to produce brewed foods such as soy sauce, miso, sake, and miso, for example, the entire amount of raw materials such as soybeans, barley, and rice used to produce the required koji is used. Koji is made by directly inoculating filamentous fungi such as Aspergillus oryzae into koji. However, in this type of koji making method,
Because the koji raw material has a high moisture content, condensed water is generated at the part where the koji raw material contacts the bottom plate of the koji making equipment.
The koji raw material is susceptible to bacterial contamination, and this contamination spreads throughout the koji raw material through subsequent handling operations, resulting in a significant deterioration in the quality of the koji. Therefore, the present inventors investigated various ways to produce solid koji that would minimize bacterial contamination from the bottom plate of the koji making equipment, and found that a portion of the carbohydrate raw material was sprinkled in advance onto the bottom plate of the koji making equipment. However, if the solid koji raw material inoculated with filamentous fungi is added onto the solid koji material and the koji is made, there is no direct contact between the bottom plate and the moisture-rich ingredients, which prevents the contamination of bacteria from the bottom plate. As a result, it is possible to suppress the growth of miscellaneous bacteria during the subsequent process of making koji, and also to encourage the growth of filamentous fungi, thereby obtaining high-quality solid koji with a high protease titer. The present invention was completed based on the knowledge that this can be done. That is, when producing solid koji according to the present invention,
A method for producing solid koji, which is characterized in that carbohydrate raw materials are spread on the bottom plate of a koji making device in advance, solid koji raw materials inoculated with filamentous fungi are poured thereon, and then koji is made by a conventional method. be. The present invention will be explained in detail below. The solid koji raw material used in the present invention may be any commonly used solid koji raw material, such as soybeans, defatted soybeans, protein raw materials such as gluten, carbohydrate raw materials such as rice, barley, and corn, and soy sauce lees. Examples include by-products generated during the manufacturing process of brewed foods such as ajirin lees, sake lees, rice bran, and fatsiyu meal. These may be used alone or in combination. Then, these solid koji raw materials as they are or with water added are denatured or pregelatinized by pressurizing and heating in a conventional manner, and are crushed if necessary. Next, a predetermined amount of the carbohydrate raw material among the solid koji raw materials obtained in this way is spread in advance on the filling bottom plate of the koji making apparatus. The loading bottom plate of the above-mentioned koji making equipment refers to the surface that comes into contact with the filling material when loading solid koji raw materials, such as the perforated plate in the ventilation koji making equipment, the net in the mesh lid, and the plate in the plate lid, and other than the above. It also includes all materials that are used to produce solid koji. The amount of carbohydrate raw materials to be sprinkled on this filled bottom plate is 0.1 to 25% (W/
W), preferably about 2 to 10% (W/W).
Then, the above-mentioned carbohydrate raw material is evenly spread on the bottom plate of the koji making apparatus. Next, the solid koji raw material consisting of the remainder of the carbohydrate raw material and the protein raw material was inoculated with filamentous fungi and mixed.
The mixture is placed on top of the carbohydrate raw material that has been spread on the above-mentioned filling bottom plate, and then koji is made by ventilation or static koji in a conventional manner for about 30 to 70 hours. The filamentous fungi used in the present invention can be used in any type of fermentation industry such as soy sauce, miso, sake, and miso, fermentation industries such as enzyme production, and filamentous fungi utilization industries, including commercially available brewing seed koji used for testing and research. Anything is fine. Specific examples thereof include Aspergillus oryzae (ATCC14895), Aspergillus phoensis (ATCC14332), and Rhizopus japonicus (IAM6002). As described above, according to the present invention, the growth of miscellaneous bacteria during koji making can be greatly reduced by preventing the ingredients on which bacteria can easily propagate from coming into direct contact with the bottom plate of the koji making device. It is extremely useful industrially because it can suppress the growth of filamentous fungi and significantly promote the growth of filamentous fungi, yielding high-quality solid koji with a high titer of enzymes such as protease. The present invention will be specifically explained below using examples. Example 1 30 kg of roasted and crushed wheat (10% W/W of the total carbohydrate raw materials used) was uniformly spread on a Kasten perforated plate of a conventional ventilation koji making apparatus. Next, 420 kg of water was sprinkled on 300 kg of defatted soybeans, and the pressure was 2
Kg/cm ² (gauge pressure) using saturated steam at a temperature of 133°C for 10 minutes, and then 270 kg of roasted cracked wheat was mixed with this, followed by seed koji of Aspergillus oryzae (ATCC14895). After 1 kg of the inoculated material was placed on top of the above-mentioned roasted cracked wheat, koji was made using a conventional method at a temperature of 30°C and ventilation at an airflow rate of 7 cm/sec for 42 hours to obtain solid koji (the present invention). . The control was obtained by making koji through ventilation in exactly the same manner as the koji making method of the present invention, except that the whole amount of roasted and crushed wheat and defatted soybeans was used at the time of mixing. Table 1 shows the number of viable bacteria, the protease titer of the koji, the number of viable bacteria, and the nitrogen utilization rate for both types of koji thus obtained. The protease titer and the number of viable bacteria were measured by the following method. ◎Measurement of protease titer After leaching the koji with 20 times the amount of water for 3 hours, 1 ml of the filtrate obtained by filtration by a conventional method was used as an enzyme solution. The titer was measured by a modified Anson-Hagiwara method at pH 7.0 using milk casein as a substrate, and was expressed as an OD value at a wavelength of 660 nm. ◎Measurement of the number of viable bacteria: Suspend 10 g of koji in 100 ml of physiological saline, plate 1 ml of this on 7 ml of medium with the following composition, and
After culturing at 35°C for 48 hours, the number of colonies that appeared was determined. <Medium composition for measuring the number of viable bacteria> Glucose 1% (W/V), meat extract 1%
(W/V), peptone 1% (W/V), salt 0.5%
(W/V), agar 1.5%, PH: 7.2 The nitrogen utilization rate is for each of the above two categories of koji.
Prepared with 25% (W/V) saline solution at 1100 °C, temperature
It is the nitrogen utilization rate of the liquid juice obtained by filtering the moromi control using the conventional method at 20-30℃ for 200 days.
Ratio of dissolved nitrogen to total nitrogen in soy sauce raw materials %
It is expressed as

[Table] As is clear from Table 1, the number of viable bacteria of the present invention is significantly lower than that of the control, and the protease titer in the koji produced is also significantly higher than that of the control. The nitrogen utilization rate was also extremely excellent. Example 2 15g of roasted and crushed wheat (5% of the total carbohydrate raw materials used) was placed on each of 5 ordinary plate lids.
W/W) was evenly spread. Separately, 1500 defatted soybeans
2,100 ml of water was sprinkled on 2,100 ml of water, and steamed under pressure for 10 minutes using saturated steam at a pressure of 2 Kg/cm ² (gauge pressure) and a temperature of 133°C. 1,425 g of roasted cracked wheat was added, and Aspergillus oryzae (ATCC14895) was added. 〓 Seed koji 5
The mixture was divided into 5 equal parts, and each was placed on a plate lid on which the above-mentioned roasted cracked wheat had been sprinkled. Then, it was cultured at 30°C for 48 hours in a constant temperature and humidity room to obtain solid koji (the present invention). In addition, the control was obtained in exactly the same manner as the koji making method of the present invention, except that the whole amount of roasted and crushed wheat and defatted soybeans was used at the time of mixing. Table 2 shows the number of viable bacteria, the protease titer of the koji, the number of viable bacteria, and the nitrogen utilization rate for both types of koji thus obtained.

It was carried out in the same manner as the measurement method in [Table].
As shown in Table 2, the number of viable bacteria of the present invention was significantly lower than that of the control, and the protease titer of the released koji was also high, and the nitrogen utilization rate was also significantly high.

Claims (1)

[Claims] 1. When producing solid koji, carbohydrate raw materials are spread on the bottom plate of the koji making equipment in advance, and after the solid koji raw materials inoculated with filamentous fungi are poured onto it,
A method for producing solid koji, which is characterized by making koji using a conventional method.