Soy sauce koji, preparation method thereof and soy sauce

Abstract

The invention provides a method for preparing soy sauce koji, comprising the following steps: A) mixing bean dregs, bran, flour and water to obtain a mixed culture medium; B) sterilizing the mixed culture medium, inoculating the koji, and continuously aerating and culturing the koji to obtain the soy sauce koji; the ventilation volume of the aeration culture is 3 to 5 m 3 / h, and the air pressure is 0.4-0.6Mpa. The present invention provides a seed koji cultivation process that does not require water replenishment, which is simple to operate, saves the equipment and labor, materials, water, electricity and gas waste required for seed koji water replenishment and humidification, and increases the thickness of single-plate paving, thereby improving the seed koji production capacity and efficiency. The storage period of the seed koji cultivated by the present invention can be extended from the original 1-2 days to more than 30 days. The seed koji production inoculation amount prepared by the present invention can be reduced by 30%, the prepared big koji and soy sauce have low miscellaneous bacteria, the soy sauce has high amino acid content, high free amino acid and glutamic acid content, the raw material utilization rate in the soy sauce is improved, and the flavor is good.

Description

Technical Field

[0001] The invention relates to the technical field of food, in particular to a soy sauce koji, a preparation method thereof and soy sauce. Background Art

[0002] Soy sauce is an essential condiment in people's lives. As living standards improve, the demand for soy sauce quality is also increasing. The koji (starter yeast) is a key factor in soy sauce brewing and is crucial to its quality. High-quality starter yeast increases yield and enhances flavor, taste, and sensory texture. However, low-quality starter yeast can lead to low enzyme activity during koji making, affecting total nitrogen utilization in the raw materials, making it difficult to prepare the mash and oil, resulting in significant economic losses.

[0003] High-quality seed koji should have characteristics such as low numbers of foreign bacteria, high germination rates, and good spore dispersion. Automatic seed koji machines produce high-quality seed koji, require less labor, and significantly improve the total bacterial count, dropping from 6-7 or more using traditional methods to under 4. However, due to production schedules and other factors, seed koji must be produced in advance. The mature seed koji has a high moisture content and a short storage time (only 1-2 days). If it is not used promptly, the bacteria will rapidly multiply to 6-7 or more within a few days. Furthermore, the high moisture content of the seed koji makes it difficult to disperse spores, which can lead to clumping when rubbing the seed koji. Uneven rubbing can easily lead to uneven inoculation, which can burn the koji. High levels of foreign bacteria in the koji are detrimental to the utilization of raw materials for improving the quality of soy sauce. Some manufacturers choose to dry the seed koji before storage, but this requires significant investment in energy-intensive equipment, significantly increasing the production cost of the seed koji.

[0004] Traditional soy sauce koji production typically uses bran, flour, and bean dregs as raw materials. To achieve a high spore count, traditional koji cultivation processes typically require extensive, continuous or intermittent watering with humidifying nozzles during the koji-making process. This humidification causes significant surface collapse, and the thickness of the material on a single tray is controlled at 1.0-1.5 cm to minimize the amount and degree of filling, limiting koji production capacity and efficiency. High moisture content can lead to a degree of compaction, resulting in poor internal growth. Some koji trays are severely contaminated by condensate, causing bacterial proliferation and a sour, smelly environment. These trays must be scraped and discarded, resulting in reduced production capacity and efficiency.

[0005] Therefore, it is particularly important to improve the production capacity and efficiency of seed koji by developing and optimizing the process while ensuring the stability of the quality of the seed koji. Summary of the Invention

[0006] In view of this, the technical problem to be solved by the present invention is to provide a soy sauce koji, which has high production capacity and long storage time.

[0007] The present invention provides a method for preparing soy sauce koji, comprising the following steps:

[0008] A) mixing bean dregs, bran, flour and water to obtain a mixed culture medium;

[0009] B) After sterilizing the mixed culture medium, inoculate the yeast and culture it with continuous ventilation to obtain the product; the ventilation rate of the aeration culture is 3-5m 3 / h, air pressure is 0.4~0.6Mpa.

[0010] Preferably, the mass ratio of the bean dregs to the bran is 7:3 to 8:2; the water content of the bean dregs is 80 wt% to 85 wt%;

[0011] Preferably, the mass ratio of bean dregs, bran, flour and water in the mixed culture medium is 6.0-7.0:1.5-2.5:4.0-8.0:0.7-1.1.

[0012] The water content in the culture medium is 60-68 wt %; the flour content in the culture medium is 4-8 wt %;

[0013] The culture medium has a thickness of 1.8 to 2.5 cm.

[0014] Preferably, the sterilization temperature in step B) is 120-125° C. and the time is 30-40 minutes.

[0015] Preferably, the inoculation in step B) is specifically as follows: the seed koji in the triangular flask is inoculated into the culture medium, the seed koji machine fan is turned on during the inoculation, and the fan frequency is 20-30HZ; the culture medium temperature during the inoculation is 30-35°C.

[0016] Preferably, the preparation method of the triangular flask koji is specifically as follows: the strain is transferred to the bean juice slant culture medium, and cultured at a constant temperature for 3 to 4 days to obtain a test tube strain; then the test tube strain on the slant is inoculated into the triangular flask culture medium, and cultured at a constant temperature for 3 to 4 days to obtain the triangular flask koji; the inoculated koji is Aspergillus oryzae, and the inoculation amount is 3 to 6‰.

[0017] Preferably, the culture period in step B) is 96 to 120 hours; and no water is sprayed during the continuous ventilation culture stage.

[0018] Preferably, the culturing specifically comprises:

[0019] The first culture stage: the culture condition is that the temperature is controlled at 30-32℃, the culture period is from 0h to 22-24h, and the fan frequency is 10-20HZ;

[0020] The second culture stage: the culture condition is that the temperature is controlled at 31-34°C, this stage lasts from 22-24 hours to 34-36 hours, and the fan frequency is 25-35HZ;

[0021] The third stage of cultivation: the cultivation condition is that the temperature is controlled at 30-33°C, this stage lasts from 34-36 hours to 44-46 hours, and the fan frequency is 15-25HZ;

[0022] The fourth stage of cultivation: the cultivation condition is that the temperature is controlled at 30-33°C, this stage lasts from 44-46 hours to 66-68 hours, and the fan frequency is 10-20 Hz;

[0023] The fifth stage of cultivation: the cultivation condition is that the temperature is controlled at 28-32°C, this stage lasts from 66-68 hours to 96-100 hours, and the fan frequency is 10-20 Hz;

[0024] The sixth stage of cultivation: the cultivation condition is that the temperature is controlled at 26-28°C, this stage lasts from 96-100h to 120-144h, and the fan frequency is 10-20HZ.

[0025] The present invention provides a soy sauce koji, which is prepared by the preparation method described in any one of the above technical solutions.

[0026] The present invention provides a soy sauce, characterized in that it is prepared from the koji described in the above technical solution.

[0027] Compared with the prior art, the present invention provides a method for preparing soy sauce koji, comprising the following steps: A) mixing bean dregs, bran, flour and water to obtain a mixed culture medium; B) sterilizing the mixed culture medium, inoculating the koji, and continuously aerating and culturing the koji to obtain the soy sauce koji; the ventilation volume of the aeration culture is 3 to 5 m 3 / h, and the air pressure is 0.4-0.6Mpa. The present invention provides a seed koji cultivation process that does not require water replenishment, which is simple to operate, saves the equipment and labor, materials, water, electricity and gas required for water replenishment and humidification of the seed koji, and increases the thickness of the single-plate material, thereby improving the seed koji production capacity and efficiency. Although the spore count of the seed koji cultivated by the present invention will be reduced, the moisture content is low, the texture is loose and there is no sandwich, the miscellaneous bacteria can be controlled within the square power, and the storage period can be extended from the original 1-2 days to more than 30 days, avoiding the pollution and waste of the seed koji due to untimely use. The seed koji prepared by the present invention is easier to disperse and utilize during koji making, the efficiency is improved, the production inoculation amount can be reduced by 30%, the prepared large koji and soy sauce have low miscellaneous bacteria, the soy sauce has a high amino acid content, high free amino acid and glutamic acid content, the raw material utilization rate in the soy sauce is improved, and the flavor is good. DETAILED DESCRIPTION

[0028] The present invention provides a soy sauce koji, a preparation method thereof, and soy sauce. Those skilled in the art can refer to the contents of this article and appropriately improve the process parameters to achieve the desired effect. It should be noted that all similar substitutions and modifications are obvious to those skilled in the art and fall within the scope of protection of the present invention. The methods and applications of the present invention have been described through preferred embodiments, and relevant personnel can obviously modify or appropriately change and combine the methods and applications herein without departing from the content, spirit, and scope of the present invention to implement and apply the technology of the present invention.

[0029] The present invention provides a soy sauce koji cultivation process, effectively solving the problems of short storage time, low production capacity, and low efficiency of koji bacteria. The process is simple to operate, reduces production costs, and improves koji quality. Soy sauce prepared using the koji produced by the present invention has high amino acid content, high free amino acid and glutamic acid content, improved raw material utilization, and good flavor, thus possessing market application value.

[0030] The present invention provides a method for preparing soy sauce koji, comprising the following steps:

[0031] A) mixing bean dregs, bran, flour and water to obtain a mixed culture medium;

[0032] B) After sterilizing the mixed culture medium, inoculate the yeast and culture it with continuous ventilation to obtain the product; the ventilation rate of the aeration culture is 3-5m 3 / h, air pressure is 0.4~0.6Mpa.

[0033] The method for preparing soy sauce koji provided by the invention comprises the following steps: firstly mixing bean dregs, bran, flour and water to obtain a mixed culture medium.

[0034] The invention provides fresh bean dregs without foreign smell and with fresh fragrance. The moisture content of the bean dregs is 80-85%.

[0035] As a byproduct of soy product processing, bean dregs are mostly used as feed or fertilizer, or even discarded as waste, polluting the environment and wasting resources. Therefore, the present invention proposes to use fresh bean dregs to replace part of the bran in the preparation of seed koji, in order to fully utilize the bean dregs resource and turn waste into treasure.

[0036] According to the present invention, the mass ratio of bean dregs, bran, flour and water in the mixed culture medium is preferably 6.0-7.0:1.5-2.5:4.0-8.0:0.7-1.1.

[0037] Specifically, the mass ratio of the bean dregs to the bran is 7:3 to 8:2; it can be specifically 7:2, 7:3, 8:2, 8:3 or any value between the above two; the water content of the bean dregs is 80wt% to 85wt%.

[0038] The water content of the culture medium is preferably 60-68 wt%, more preferably 62-66 wt%. The flour content of the culture medium is 4-8 wt%, more preferably 5-7 wt%. The thickness of the culture medium is 1.8-2.5 cm.

[0039] Spread the mixed culture medium on the curved plate in a quantitative manner, and use a rake hook to gently make hook marks on the surface of the material.

[0040] Sterilize the mixed culture medium. Specifically, sterilize the culture medium and inoculation tank with steam and cool to the inoculation temperature.

[0041] The sterilization temperature is 120-125° C., and the time is 30-40 min; more preferably, the sterilization temperature is 121-124° C., and the time is 32-38 min.

[0042] The inoculation described in the present invention is specifically as follows: the seed koji in the triangular bottle is inoculated into the culture medium, and the seed koji machine fan is turned on during the inoculation, and the fan frequency is 20-30HZ; more preferably 22-28HZ; the culture medium temperature during inoculation is 30-35°C; more preferably 31-34°C.

[0043] Specifically, the preparation method of the triangular flask koji is as follows: the strain is transferred to the bean juice slant culture medium, and cultured at a constant temperature for 3 to 4 days to obtain a test tube strain; then the test tube strain on the slant is inoculated into the triangular flask culture medium, and cultured at a constant temperature for 3 to 4 days to obtain the triangular flask koji; the inoculated koji is Aspergillus oryzae, and the inoculation amount is 3 to 6‰; more preferably 3 to 5‰.

[0044] After sterilization, the koji seeds are inoculated and continuously aerated and cultured to obtain the product; the aeration volume of the aeration culture is 3 to 5 m 3 / h, air pressure is 0.4~0.6Mpa.

[0045] The culture cycle of the present invention is 96 to 120 hours; and no water is sprayed during the continuous ventilation culture stage.

[0046] According to the present invention, the culture is specifically:

[0047] The first culture stage: the culture condition is that the temperature is controlled at 30-32℃, the culture period is from 0h to 22-24h, and the fan frequency is 10-20HZ;

[0048] The second culture stage: the culture condition is that the temperature is controlled at 31-34°C, this stage lasts from 22-24 hours to 34-36 hours, and the fan frequency is 25-35HZ;

[0049] The third stage of cultivation: the cultivation condition is that the temperature is controlled at 30-33°C, this stage lasts from 34-36 hours to 44-46 hours, and the fan frequency is 15-25HZ;

[0050] The fourth stage of cultivation: the cultivation condition is that the temperature is controlled at 30-33°C, this stage lasts from 44-46 hours to 66-68 hours, and the fan frequency is 10-20 Hz;

[0051] The fifth stage of cultivation: the cultivation condition is that the temperature is controlled at 28-32°C, this stage lasts from 66-68 hours to 96-100 hours, and the fan frequency is 10-20 Hz;

[0052] The sixth stage of cultivation: the cultivation condition is that the temperature is controlled at 26-28°C, this stage lasts from 96-100h to 120-144h, and the fan frequency is 10-20HZ.

[0053] The present invention provides a soy sauce koji, which is prepared by the preparation method described in any one of the above technical solutions.

[0054] The present invention provides a soy sauce, characterized in that it is prepared from the koji described in the above technical solution.

[0055] The invention provides a method for preparing soy sauce koji, comprising the following steps: A) mixing bean dregs, bran, flour and water to obtain a mixed culture medium; B) sterilizing the mixed culture medium, inoculating the koji, and continuously aerating and culturing the koji to obtain the soy sauce koji; the ventilation volume of the aeration culture is 3 to 5 m 3 / h, and the air pressure is 0.4-0.6Mpa. The present invention provides a seed koji cultivation process that does not require water replenishment, which is simple to operate, saves the equipment and labor, materials, water, electricity and gas required for water replenishment and humidification of the seed koji, and increases the thickness of the single-plate material, thereby improving the seed koji production capacity and efficiency. Although the spore count of the seed koji cultivated by the present invention will be reduced, the moisture content is low, the texture is loose and there is no sandwich, the miscellaneous bacteria can be controlled within the square power, and the storage period can be extended from the original 1-2 days to more than 30 days, avoiding the pollution and waste of the seed koji due to untimely use. The seed koji prepared by the present invention is easier to disperse and utilize during koji making, the efficiency is improved, the production inoculation amount can be reduced by 30%, the prepared large koji and soy sauce have low miscellaneous bacteria, the soy sauce has a high amino acid content, high free amino acid and glutamic acid content, the raw material utilization rate in the soy sauce is improved, and the flavor is good.

[0056] To further illustrate the present invention, a soy sauce koji, a preparation method thereof, and soy sauce provided by the present invention are described in detail below with reference to examples.

[0057] Example 1

[0058] Step 1: Material preparation: Prepare fresh, odorless, and fragrant bean dregs with a moisture content of 80%.

[0059] Step 2: Mixing: Stir and crush bean dregs, bran, flour and water in a certain proportion until evenly mixed. The ratio of bean dregs to bran is 8:2. Add 4% flour and 7% water.

[0060] Step 3: Plate and spread the mixed culture medium on the curved plate in a quantitative manner, and use a rake to gently make hook marks on the surface of the material with a thickness of 2.5 cm.

[0061] Step 4: Sterilization and cooling: Sterilize the culture medium and inoculation canister with steam at 120°C for 40 minutes.

[0062] Step 5: Inoculation: When the material temperature drops to 35°C, inoculate the koji seeds in the triangular bottle into the culture medium through the inoculation can and sterile air. When inoculating, turn on the koji seed machine fan, the fan frequency is 30HZ, and the inoculation amount is 8‰

[0063] Step 6: Cultivation: Continuous aeration cultivation is carried out without spraying water during the whole process until the seed koji is mature, with a ventilation volume of 5m 3 / h, air pressure of 0.6Mpa, and a cultivation period of 144h; First cultivation stage: the cultivation condition is temperature controlled at 30-32℃, this stage lasts for 0-24h, and the fan frequency is 20HZ; Second cultivation stage: the cultivation condition is temperature controlled at 31-34℃, this stage lasts for 24-36h, and the fan frequency is 35HZ; Third cultivation stage: the cultivation condition is temperature controlled at 30-33℃, this stage lasts for 36-46h, and the fan frequency is 25HZ. Fourth cultivation stage: the cultivation condition is temperature controlled at 30-33℃, this stage lasts for 46-68h, and the fan frequency is 20HZ. Fifth cultivation stage: the cultivation condition is temperature controlled at 28-32℃, this stage lasts for 68-100h, and the fan frequency is 20HZ. The sixth stage of cultivation: the cultivation condition is that the temperature is controlled at 26-28°C, this stage lasts for 100-144 hours, and the fan frequency is 20HZ.

[0064] Example 2

[0065] Step 1: Material preparation: Prepare fresh, odorless, and fragrant bean dregs with a moisture content of 85%.

[0066] Step 2: Mixing: Stir and crush bean dregs, bran, flour and water in a certain proportion until evenly mixed. The ratio of bean dregs to bran is 7:3. Add appropriate amount of flour 8% and water 11%.

[0067] Step 3: Plate and spread the mixed culture medium on the curved plate in a quantitative manner, and use a rake to gently make hook marks on the surface of the material with a thickness of 1.8 cm.

[0068] Step 4: Sterilization and cooling: Sterilize the culture medium and inoculation canister with steam at 120°C for 30 minutes.

[0069] Step 5: Inoculation: When the material temperature drops to 35°C, inoculate the koji seeds in the triangular bottle into the culture medium through the inoculation can and sterile air. When inoculating, turn on the koji seed machine fan, the fan frequency is 20HZ, and the inoculation amount is 4‰

[0070] Step 6: Cultivation: Continuous aeration cultivation is carried out without spraying water during the whole process until the seed koji is mature, with a ventilation volume of 3m 3 / h, air pressure of 0.4 MPa, and a 120-hour incubation period. First incubation stage: The incubation temperature is controlled at 30-32°C, lasting from 0 to 22 hours, with a fan frequency of 10 Hz. Second incubation stage: The incubation temperature is controlled at 31-34°C, lasting from 22 to 34 hours, with a fan frequency of 25 Hz. Third incubation stage: The incubation temperature is controlled at 30-33°C, lasting from 34 to 44 hours, with a fan frequency of 15 Hz. Fourth incubation stage: The incubation temperature is controlled at 30-33°C, lasting from 44 to 66 hours, with a fan frequency of 10 Hz. Fifth incubation stage: The incubation temperature is controlled at 28-32°C, lasting from 66 to 96 hours, with a fan frequency of 10 Hz. Sixth incubation stage: The incubation temperature is controlled at 26-28°C, lasting from 96 to 120 hours, with a fan frequency of 10 Hz.

[0071] Example 3

[0072] Step 1: Material preparation: Prepare fresh, odorless, and fragrant bean dregs with a moisture content of 83%.

[0073] Step 2: Mixing: Stir and crush bean dregs, bran, flour and water in a certain proportion. The ratio of bean dregs to bran is 7.5:2.5. Add appropriate amount of flour 6% and water 9%.

[0074] Step 3: Plate and spread the mixed culture medium on the plate in a fixed amount. Use a rake to gently make hook marks on the surface of the material with a thickness of 2.1 cm.

[0075] Step 4: Sterilization and cooling: Sterilize the culture medium and inoculation canister with steam at 120°C for 35 minutes.

[0076] Step 5: Inoculation: When the material temperature drops to 35°C, inoculate the koji seeds in the triangular bottle into the culture medium through the inoculation can and sterile air. When inoculating, turn on the koji seed machine fan, the fan frequency is 30HZ, and the inoculation amount is 6‰

[0077] Step 6: Cultivation: Continuous aeration cultivation is carried out without spraying water during the whole process until the seed koji is mature, with a ventilation volume of 4m 3 / h, air pressure of 0.5 MPa, and a cultivation period of 132 hours. First cultivation stage: The cultivation condition is controlled at a temperature of 30-32°C, which lasts from 0 to 23 hours, and the fan frequency is 15 Hz. Second cultivation stage: The cultivation condition is controlled at a temperature of 31-34°C, which lasts from 23 to 35 hours, and the fan frequency is 30 Hz. Third cultivation stage: The cultivation condition is controlled at a temperature of 30-33°C, which lasts from 35 to 45 hours, and the fan frequency is 20 Hz. Fourth cultivation stage: The cultivation condition is controlled at a temperature of 30-33°C, which lasts from 45 to 67 hours, and the fan frequency is 15 Hz. Fifth cultivation stage: The cultivation condition is controlled at a temperature of 28-32°C, which lasts from 67 to 98 hours, and the fan frequency is 15 Hz. Sixth cultivation stage: The cultivation condition is controlled at a temperature of 26-28°C, which lasts from 98 to 132 hours, and the fan frequency is 15 Hz.

[0078] Comparative Example 1:

[0079] Step 6: Cultivation: Continuous ventilation cultivation is performed, humidification is performed once every 2 hours, 10 minutes, and the amount of water added per minute is 100 mL, until the seed koji is mature. The remaining steps are the same as in Example 1

[0080] Comparative Example 2:

[0081] Step 6: Cultivation: Continuous ventilation cultivation is performed, humidification is performed once every 2 hours, 10 minutes, and the amount of water added per minute is 100 mL, until the seed koji is mature. The remaining steps are the same as in Example 2

[0082] Comparative Example 3:

[0083] Step 6: Cultivation: Continuous ventilation cultivation is performed, humidification is performed once every 2 hours, 10 minutes, and the amount of water added per minute is 100 mL, until the seed koji is mature. The remaining steps are the same as in Example 3

[0084] Comparative Example 4:

[0085] Step 2: Mixing: stir and grind bean dregs, bran, flour and water in a certain proportion and mix them evenly. The ratio of bean dregs to bran is 5:5. Add 4% flour and 50% water. The rest of the steps are the same as in Example 1.

[0086] Comparative Example 5:

[0087] Step 2: Mixing: Mix the bean dregs, bran, flour and water in a certain proportion by stirring and crushing. The ratio of bran to water is 1:1. Add 4% flour. Place the material on a plate with a thickness of 1.5 cm. The incubation period is 72 hours. The rest of the steps are the same as those in Control Example 1.

[0088] The seed koji obtained by the cultivation of Examples 1-3 and the comparative example were respectively tested and sensory evaluated, and the results are shown in Table 1.

[0089] Table 1 Summary of comparison results of the seed koji obtained by cultivation of Examples 1-3 and the comparative examples

[0090]

[0091]

[0092] Table 2 Summary of the comparison results of bacterial counts of the seed koji obtained by Examples 1-3 and the comparative examples at different storage times

[0093]

[0094] Table 3 Comparison of germination rates of the koji obtained by Example 1-3 and the comparative example at different storage times

[0095]

[0096] From Table 1, Table 2, Table 3, and the comparison results of the seed koji obtained by culturing Examples 1-3 and the comparative example, it can be seen that the seed koji obtained by culturing the seed koji provided by the present invention has an overall yellow-green, uniform, loose, and no sandwich, and the seed powder pre-mixed with flour has no lumps, and the germination rate has no obvious difference and can reach more than 98%. The spore count and moisture content are low, but the shelf life of the seed koji can be extended to more than 30 days. At this time, the quality of the seed koji is still excellent, with low foreign bacteria and high germination rate.

[0097] Koji making and fermentation to prepare soy sauce:

[0098] (1) Raw material pretreatment: Soybeans were mixed with water in a ratio of 1 (kg): 2-3 (L) and soaked for 8 h, then drained and set aside;

[0099] (2) Steaming: Steam the drained soybeans at 121°C for 15 min;

[0100] (3) Mixing: Soybeans cooled to 40°C and flour are mixed evenly in a mass ratio of 2:1;

[0101] (4) Koji making: The mixture of soybeans and flour was cooled to 35°C, and the seed koji obtained by culturing Examples 1-3 and the comparative example was inoculated, with the inoculum amount of 2‰ for Examples 1-3 and 3‰ for the comparative example. The mixture was then ventilated at 30°C and cultured for 42 hours to obtain finished koji.

[0102] (5) Fermentation: The prepared koji and 22% saline solution were mixed in a mass ratio of 1:2, and fermented at a constant temperature of 35°C for 120 days to obtain mature mash.

[0103] (6) Oil extraction: The soy sauce mash is squeezed using a soy sauce press, stored in a tank and allowed to stand for 3 days, the supernatant is extracted and filtered through diatomaceous earth to obtain the soy sauce crude oil.

[0104] Table 4 Summary of the comparison results of soy sauce prepared from the seed koji obtained by Examples 1-3 and the comparative examples

[0105]

[0106] As can be seen from Table 4, the present invention provides a method for brewing soy sauce using koji. The prepared koji has low foreign bacteria content, high enzyme activity, high soy sauce amino acid content, high free amino acid and glutamic acid content, improved raw material utilization in the soy sauce, and good flavor.

[0107] Comparison of characteristic indicators between the seed koji prepared by the present invention and the traditional seed koji

[0108]

[0109]

[0110] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present invention. These improvements and modifications should also be regarded as within the scope of protection of the present invention.

Claims

1. A method for preparing soy sauce koji, characterized in that: The steps include: Step 1: Material preparation: Prepare fresh, odorless, and fragrant bean dregs with a moisture content of 85%; Step 2: Mixing: Stir and crush bean dregs, bran, flour and water in a certain proportion. The ratio of bean dregs to bran is 7:

3. Add appropriate amount of flour 8% and water 11%. Step 3: Plate and spread the mixed culture medium on the curved plate in a fixed amount. Use a rake to gently make hook marks on the surface of the material to a thickness of 1.8 cm. Step 4: Sterilization and cooling: Sterilize the culture medium and inoculation canister with steam at 120°C for 30 minutes, and sterilize the inoculation canister at the same time; Step 5: Inoculation: After the material temperature drops to 35°C, the triangular flask koji is inoculated into the culture medium through an inoculation can and sterile air. During inoculation, the koji machine fan is turned on, the fan frequency is 20HZ, and the inoculation amount is 4‰; the preparation method of the triangular flask koji is specifically as follows: the bacteria are transferred to the bean juice slant culture medium, and cultured at a constant temperature for 3 to 4 days to obtain a test tube seed; then the test tube seed on the slant is inoculated into the triangular flask culture medium, and cultured at a constant temperature for 3 to 4 days to obtain the triangular flask koji; the inoculated koji is Aspergillus oryzae; Step 6: Cultivation: Continuous ventilation cultivation is carried out without water spraying throughout the process until the seed koji is mature. The ventilation volume is 3m³ / h, the air pressure is 0.4Mpa, and the cultivation period is 120h. The first cultivation stage: the cultivation condition is that the temperature is controlled at 30-32℃, the stage lasts for 0-22h, and the fan frequency is 10HZ; the second cultivation stage: the cultivation condition is that the temperature is controlled at 31-34℃, the stage lasts for 22-34h, and the fan frequency is 25HZ; the third stage cultivation: the cultivation condition is that the temperature is controlled at 3 0~33℃, this stage lasts for 34~44h, the fan frequency is 15HZ; the fourth stage of cultivation: the temperature is controlled at 30~33℃, this stage lasts for 44~66h, the fan frequency is 10HZ; the fifth stage of cultivation: the temperature is controlled at 28~32℃, this stage lasts for 66~96h, the fan frequency is 10HZ; the sixth stage of cultivation: the temperature is controlled at 26~28℃, this stage lasts for 96~120h, the fan frequency is 10HZ.

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