Maotai-flavor yeast for making hard liquor and preparation method thereof

Abstract

The invention discloses Maotai-flavor yeast for making hard liquor and a preparation method thereof, and belongs to the technical field of Maotai-flavor yeast making. The Maotai-flavor yeast for making hard liquor comprises the following raw materials in percentage by weight: 50-100wt% of highland barley ferment powder and 0-50wt% of wheat flour, and further comprises grain moistening water which accounts for 38-42% of the total mass of the highland barley ferment powder and the wheat flour and mother yeast powder which accounts for 3-8% of the mass of the wheat flour; the Maotai-flavor yeast for making hard liquor is prepared through the technological processes of preparation of highland barley ferment powder, preparation of wheat flour, mixing of the wheat flour and the highland barley ferment powder, yeast blank forming, yeast mounting, yeast blank fermentation, yeast dismounting and warehousing and storage. The preparation method solves the problems of slow fermentation, unsatisfactory fermentation and the like caused by high viscosity of the yeast blank when the highland barley is used as the raw material to prepare the yeast; meanwhile, the problem of low abundance of yeast rock bacillus in Sichuan sauce type yeast for making hard liquor is solved; furthermore, the thick sense of the sauce flavor of the Sichuan sauce type yeast is optimized, and the overall quality of the sauce-flavor yeast is improved.

Description

Technical Field

[0001] The invention belongs to the technical field of sauce-flavored Daqu manufacturing and the fields of characteristic agricultural product processing and agricultural industrialization, and relates to a production method for improving the overall quality of Sichuan sauce-flavored Daqu, and specifically relates to a sauce-flavored Daqu and a preparation method thereof. Background Art

[0002] Highland barley is a type of naked barley, mainly grown in Tibet, Qinghai, Sichuan (Ganzi, Aba Prefecture) and Gansu. The utilization of highland barley is still in the stage of regional deep processing, mainly simple processing into tsampa or brewing highland barley wine. It is one of the most distinctive crops on the Qinghai-Tibet Plateau. Highland barley is rich in β-glucan, dietary fiber, oleic acid and other functional ingredients, and has the efficacy of assisting in reducing the "three highs". Highland barley has high hardness, thick cell walls, and does not have the structural and functional characteristics of wheat gluten protein, which limits the application of highland barley in the field of food processing. In the field of sauce-flavored Daqu manufacturing technology, many studies and productions have found that when highland barley is used as raw material to prepare Daqu, there are problems such as slow fermentation and unsatisfactory fermentation due to the high viscosity of the koji. Therefore, it is very necessary to optimize the applicability of highland barley koji making process.

[0003] As a microbial inoculant, saccharification fermentation agent and aroma agent in the brewing process of Maotai-flavor liquor, Maotai-flavor Daqu is an important factor affecting the quality of liquor. Maotai-flavor Daqu is made of wheat, barley, production water and mother koji as the main raw materials, and new and old straw as auxiliary materials, using raw material koji making technology and high-temperature fermentation. The entire preparation environment is open, so in addition to the mother koji, wheat, koji making water, straw, operating tools and microorganisms in the environment can directly enter the koji making microbial community, which is an important source of Daqu microorganisms. Due to its complex production process, process control relying on experience and regional factors, the quality of Daqu is unstable and has large regional differences, especially the low content of pyrazines in Sichuan Maotai Daqu and the low abundance of Scopulibacillus in Daqu, which affects the overall quality of Maotai-flavor Daqu.

[0004] Therefore, in view of the above technical problems, it is now urgent to study a production process that uses highland barley as raw material to make koji and can improve the overall quality of Maotai-flavor Daqu. Summary of the invention

[0005] The technical problem to be solved by the present invention is that the existing highland barley koji making process has the problem of affecting the fermentation effect due to the adhesion of the koji blanks, and the overall quality of the sauce-flavored koji is unstable due to the low content of pyrazine substances and the low abundance of Bacillus in the koji rock.

[0006] In order to achieve the above application purpose, the technical solution adopted by the present invention is as follows:

[0007] In a first aspect, the present invention provides a sauce-flavored Daqu, wherein the koji-making raw materials include 50-100% of highland barley fermentation powder and 0-50% of wheat flour by mass percentage, and also include grain moistening water accounting for 38-42% of the total mass of highland barley fermentation powder and wheat flour and mother koji powder accounting for 3-8% of the mass of wheat flour.

[0008] In the above-mentioned sauce-flavored Daqu, the preparation method of the highland barley fermented powder is: adding water to the raw highland barley to moisten the grain, and then piling the moistened material; crushing the moistened highland barley to obtain highland barley powder; adding the crushed mother koji to mix evenly, and piling up for fermentation.

[0009] Furthermore, the amount of water used for moistening the grain is 8-20% of the mass of the raw barley grain, and the piling and moistening time is 6-12 hours.

[0010] Furthermore, the fine powder of highland barley flour that can pass through a 1.2 mm sieve hole accounts for 30-50%, and the whole grain highland barley does not exceed 5%.

[0011] Furthermore, the amount of mother koji powder added is 3-8% of the mass of highland barley powder, and the stacking fermentation time is 6-24 hours.

[0012] In the above-mentioned sauce-flavored Daqu, or in the method for preparing highland barley fermented powder, the method for preparing the mother koji powder is: crushing the mature sauce-flavored Daqu stored for 3 to 8 months, and the degree of crushing is that the fine powder that can pass through a 1.2 mm sieve hole accounts for 60 to 80%.

[0013] In the above-mentioned sauce-flavored Daqu, the preparation method of the wheat flour is: adding water to the wheat raw grains to moisten the grains, and then piling the moistened materials; and crushing the moistened wheat to obtain wheat flour.

[0014] Furthermore, the amount of water used for moistening the grain is 1 to 10% of the mass of the wheat raw grain, and the material is piled up and moistened for 1 to 12 hours.

[0015] Furthermore, the fine powder of wheat flour that can pass through a 1.2 mm sieve hole accounts for 35-55%, and the whole wheat grain does not exceed 3%.

[0016] In a second aspect, the present invention provides a method for preparing the above-mentioned Maotai-flavor Daqu, which specifically comprises the following steps:

[0017] (1) highland barley fermented powder and wheat flour are compounded to obtain a mixed powder, and then mother koji powder and grain moistening water are added to mix the material to obtain koji material;

[0018] (2) The koji material is manually pressed or mechanically pressed according to the specifications of the large koji mold to form a koji blank;

[0019] (3) The koji billets are transported to the fermentation room for koji placement and fermentation. The process control of the fermentation process is as follows: when the temperature rises to 60-65°C, the doors and windows are opened and the koji is turned over for the first time, and the humidity in the koji room is above 80%; when the temperature rises to 58-60°C after the first turning of the koji, the doors and windows are opened and the koji is turned over for the second time, and the humidity in the koji room is above 70%; when the temperature rises to 52-55°C after the second turning of the koji, the doors and windows are opened for ventilation and dehumidification;

[0020] (4) After the fermentation of the koji is completed, the koji is disassembled and stored in a warehouse to obtain the sauce-flavored koji.

[0021] In the preparation method of the above-mentioned sauce-flavored Daqu, in step (1), highland barley fermented powder accounts for 50-100% of the mass of the mixed powder, wheat flour accounts for 0-50% of the mass of the mixed powder, the added amount of mother koji powder is 3-8% of the mass of the wheat flour, and the added amount of grain moistening water is 38-42% of the mass of the mixed powder.

[0022] In the above-mentioned method for preparing the sauce-flavored Daqu, in step (3), when placing the qu, a layer of straw with a thickness of 15 to 30 cm is first laid in the fermentation room, and then the qu blanks are stacked in the qu room in an orderly manner in a "three horizontal and three vertical" pattern; and after each layer of qu is laid, new and old straw and a certain amount of water are added for inoculation, heat preservation and moisture retention.

[0023] In the above-mentioned method for preparing Maotai-flavor Daqu, in step (4), the fermentation time is 38 to 42 days, and the koji can be removed and stored when the moisture content of the koji drops to 15%.

[0024] In the above method for preparing Maotai-flavor Daqu, in step (4), the storage period of the koji blank is 3 to 6 months, and the moisture content of the finished koji is controlled to be below 13%.

[0025] Beneficial effects: The present invention proposes a koji making process of stacked fermented highland barley fermentation powder. The prepared highland barley fermentation powder contains a large amount of 2,3-butanedione and 3-hydroxy-2-butanone and other precursor substances for generating tetramethylpyrazine. The present invention innovatively uses it for the preparation of sauce-flavored Daqu, thereby increasing the abundance of the genus Scopulibacillus in the Daqu of Sichuan sauce-flavored Daqu, and at the same time increasing the content of pyrazine substances in the sauce-flavored Daqu, thereby improving the overall quality of the Daqu, and overcoming the deficiency of unstable quality of the Daqu caused by traditional Sichuan sauce-flavored Daqu preparation methods and regional factors. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 It is a schematic diagram of the production process of the present invention. DETAILED DESCRIPTION

[0027] In order to make the technical problems, technical solutions and beneficial effects to be solved by the present application more clear, the present application is further described in detail below in combination with the implementation methods. Unless otherwise defined, all scientific and technological terms used herein have the same meanings as understood by ordinary technicians in the field.

[0028] The invention discloses a method for preparing Maotai-flavor Daqu, and the process flow is as follows: Figure 1 As shown, the specific steps include the following steps.

[0029] 1. Preparation of highland barley fermented powder

[0030] 1-1 Select highland barley with full grains, no mildew, no germination, no insect infestation, and no foreign matter as the raw grain for koji making, and moisten the raw barley with 8-20% of production water; pile and moisten the grain with normal temperature water for 6-12 hours in summer; pile and moisten the grain with 90-100℃ water in winter for 6-8 hours; if it is found to be too dry, add 1-3% of the raw barley water.

[0031] 1-2 Crush the moistened highland barley, requiring the "core to be rotten but the skin to be intact", of which 30-50% is fine powder that can pass through a 1.2mm sieve, and the whole grain of highland barley should not exceed 5%. It should be slightly coarse in winter and slightly fine in summer to obtain highland barley flour.

[0032] 1-3 Add highland barley flour to 3-8% of the weight of highland barley mother koji powder to mix the material, use a production line wheel or a mixer or mix it evenly manually, and pile up and ferment the mixed material for 6-24 hours to obtain highland barley fermented powder.

[0033] Preferably, the preparation method of the mother koji powder is: crushing the mature sauce-flavored koji stored for 3 to 8 months, and the degree of crushing is that the fine powder that can pass through a 1.2 mm sieve hole accounts for 60 to 80%; it is slightly finer in winter and the amount added is slightly more, and it is slightly coarser in summer and the amount added is slightly lower.

[0034] 2. Preparation of Wheat Flour

[0035] 2-1 Choose wheat with full grains, no mildew, no germination, no insect infestation, and no foreign matter as the raw grain for compound koji making. Moisten the wheat raw grain with 1-10% production water, and then pile it up to moisten the grain for 1-12 hours. If it is found to be too dry, add 1-3% water of the wheat raw material.

[0036] 2-2 The moistened wheat is crushed, with the core being rotten but the skin being intact. The fine powder that can pass through a 1.2mm sieve hole accounts for 35-55%, and the whole wheat grains do not exceed 3%, thus obtaining wheat flour.

[0037] 3. Preparation of Maotai-flavor Daqu

[0038] 3-1 Compound highland barley fermented powder and wheat flour in a mass ratio of 5-10:0-5, add 3-8% of the weight of wheat flour mother koji powder, add water and mix the materials, use a production line wheel or mixer or mix them manually to mix them evenly, the koji material should be dough-free and loose, and it should not be sticky when kneaded by hand, and the palm of the hand should be moist but not watery after kneading, and it should be of uniform hardness and softness.

[0039] 3-2 The koji material is manually pressed into shape according to the specifications of the large koji mold, or mechanically pressed into shape. The koji blank forming requirements are that the four corners of the koji blank are neat, the surface is smooth, the four sides are pressed tightly, the middle is slightly loose, the thickness is uniform, there is no missing edges or corners, the koji blank is moist and elastic, and it does not crack when placed upright.

[0040] 3-3 The prepared koji is transported to the koji room for fermentation. The fermentation room is required to first lay a layer of straw with a thickness of about 15 to 30 cm, and then the koji is stacked in order in the koji room in a "three horizontal and three vertical" pattern; and after each layer of koji is laid, new and old straw and water are added for inoculation, heat preservation and moisture retention; according to the process requirements, when the temperature of the koji reaches a certain temperature, process control and koji turning operations are carried out. When the temperature rises to 60-65℃, the first door and window opening and koji turning operations are carried out, and the humidity in the koji room is above 80%; when the temperature rises to 58-60℃ after the first koji turning, the second door and window opening and koji turning operations are carried out, and the humidity in the koji room is above 70%; when the temperature rises to 52-55℃ after the second koji turning, the doors and windows are opened for ventilation and moisture removal.

[0041] 3-4 After fermentation for 38-42 days, when the moisture content of the koji billet drops to 15%, the mature koji blocks can be separated and stored. Before storage, the straw on the koji billet is manually cleaned and transferred to a clean, dry and ventilated storage bin for orderly stacking and storage. During storage, the warehouse should be closed and moisture should be drained intermittently. The storage period of the koji billet is required to be 3-6 months. The moisture content of the finished koji is controlled below 13% and it can be put into production and use.

[0042] Preferably, when the temperature is low in winter, a layer of straw mat should be covered on the koji pile to prevent the growth of penicillium on the koji blank due to low temperature and high humidity.

[0043] Specific examples will be listed below to explain the scheme of the present invention. It will be appreciated by those skilled in the art that the following examples are only used to illustrate the present invention and should not be considered as limiting the scope of the present invention. Where specific techniques or conditions are not indicated in the examples, the techniques or conditions described in the literature in this area or the product instructions are used. Reagents or instruments used that do not indicate manufacturers are all conventional products that can be obtained commercially.

[0044] Example

[0045] 1. Preparation of Maotai-flavor Daqu

[0046] Comparative Example In the present invention, in order to better highlight the innovative features of the present invention, the process of 100% wheat is used as a comparative example to demonstrate the technical advantages of the present invention by comparing the same batch tests.

[0047] A method for preparing a sauce-flavor high-temperature Daqu (taking the production of Daqu in a fermentation room as an example), comprising the following steps:

[0048] 16 tons of high-quality wheat were selected, and the requirements were that the grains were full, without mildew, germination, insects, or foreign matter. The water temperature for tempering the wheat was 95°C, 3% was added, and the tempering time was 1 hour. After the wheat was tempered, it was crushed with a steel mill. The sensory requirements were that there were no whole grains of wheat, no coarse pieces, no greasy or rough touch, no rotten heart or skin, and the fine powder passing through the 1.2mm sieve accounted for 40%, and wheat flour was obtained.

[0049] Mix wheat flour and 6% mother koji powder (70% of the fine powder passing through a 1.2mm sieve) evenly, add room temperature water to mix the ingredients, and control the moisture content of the koji to 40%. Then make the bagged koji. Manually place the fresh koji on a pallet truck and pull it to the koji room for koji setting. A total of 2,400 pieces / room. After the koji is set, close the doors and windows for fermentation. The first koji turning time is the 8th day; the second koji turning is carried out on the 16th day; the doors and windows are opened on the 21st day for ventilation and moisture removal. After fermentation for 40 days, the koji is removed and stored. Sampling is carried out for sensory, biochemical indexes, flavor components, and microbial community testing.

[0050] Test Example 1 Producing the same kind of Maotai-flavor high-temperature Daqu as the control example (taking the production of Daqu in a fermentation room as an example), comprising the following steps:

[0051] First, 8 tons of high-quality highland barley are selected, and the grains are required to be full, free of mildew, germination, insects, and debris. The water temperature for moistening is 95°C, 15% is added, and the moistening time is 6 hours. After the moistening is completed, it is crushed with a steel mill. The sensory requirements are that the heart is rotten but the skin is not rotten, and the fine powder passing through the 1.2mm sieve hole accounts for 30%. The highland barley powder and 6% mother koji powder (the fine powder passing through the 1.2mm sieve hole accounts for 70%) are mixed evenly, and the pile fermentation is carried out for 12 hours to obtain highland barley fermentation powder.

[0052] Then select 8 tons of high-quality wheat, add 3% of water to temper the wheat at 95℃ for 1 hour. After tempering, use a steel mill to grind the wheat. The sensory requirements are that there is no whole wheat, no coarse pieces, no greasy or rough touch, no rotten heart or skin, and the fine powder passing through the 1.2mm sieve hole accounts for 40%, and wheat flour is obtained.

[0053] Mix highland barley fermented powder, wheat flour, and 6% mother koji powder by weight of wheat evenly, add room temperature water to mix the ingredients, and control the moisture content of the koji to 40%. Then make the koji in bags. Manually place the fresh koji on a pallet truck and pull it to the koji room for koji setting. A total of 2,400 pieces / room. After the koji is set, close the doors and windows for fermentation. The first koji turning time is the 8th day; the second koji turning is carried out on the 16th day; the doors and windows are opened on the 21st day for ventilation and moisture removal. After fermentation for 40 days, the koji is removed and stored. Sampling is carried out for sensory, biochemical indexes, flavor components, and microbial community testing.

[0054] Test Example 2 Producing the same kind of Maotai-flavor high-temperature Daqu as the control example (taking the production of Daqu in a fermentation room as an example), comprising the following steps:

[0055] First, 11.2 tons of high-quality highland barley are selected, and the grains are required to be full, free of mildew, germination, insects, and debris. The water temperature for moistening is 95°C, 15% is added, and the moistening time is 6 hours. After the moistening is completed, it is crushed with a steel mill. The sensory requirements are that the heart is rotten but the skin is not rotten, and the fine powder passing through the 1.2mm sieve hole accounts for 30%. The highland barley powder and 6% mother koji powder (the fine powder passing through the 1.2mm sieve hole accounts for 70%) are mixed evenly, and the pile fermentation is carried out for 12 hours to obtain highland barley fermentation powder.

[0056] Then select 4.8 tons of high-quality wheat, add 3% of water at 95℃ and the tempering time is 1 hour. After the tempering is completed, use a steel mill to grind the wheat. The sensory requirements are that there is no whole wheat, no coarse pieces, no greasy or rough touch, no rotten heart or skin, and the fine powder passing through the 1.2mm sieve hole accounts for 40%, and wheat flour is obtained.

[0057] Mix highland barley fermentation powder, wheat flour and 6% mother koji powder evenly, add room temperature water to mix, and control the moisture content of the koji to 40%. Then make it into bagged koji. Manually place the fresh koji on a pallet truck and pull it to the koji room for koji setting. A total of 2,400 pieces / room. After the koji is set, close the doors and windows for fermentation. The first koji turning time is the 8th day; the second koji turning is carried out on the 16th day; the doors and windows are opened on the 21st day for ventilation and moisture removal. After fermentation for 40 days, the koji is removed and stored. Sampling is carried out for sensory, biochemical indexes, flavor components, and microbial community testing.

[0058] Test Example 3 produces the same kind of sauce-flavor high-temperature Daqu as the control example (taking the production of Daqu in a fermentation room as an example), comprising the following steps:

[0059] First, 16 tons of high-quality highland barley are selected, and the grains are required to be full, free of mildew, germination, insects, and debris. The water temperature for moistening is 95°C, 15% is added, and the moistening time is 6 hours. After the moistening is completed, it is crushed with a steel mill. The sensory requirements are that the heart is rotten but the skin is not rotten, and the fine powder passing through the 1.2mm sieve hole accounts for 30%. The highland barley powder and 6% mother koji (the fine powder passing through the 1.2mm sieve hole accounts for 70%) are mixed evenly, and the pile fermentation is carried out for 12 hours to obtain highland barley fermentation powder.

[0060] Add highland barley fermentation powder to room temperature water and mix the ingredients, and control the moisture content of the koji to 40%. Then make the koji in bags. Manually place the fresh koji on a pallet truck and pull it to the koji room for koji setting. A total of 2,400 pieces / room. After the koji setting is completed, close the doors and windows for fermentation. The first koji turning time is the 8th day; the second koji turning is carried out on the 16th day; the doors and windows are opened on the 21st day for ventilation and moisture removal. After fermentation for 40 days, the koji is removed and stored. Sampling is carried out for sensory, biochemical indexes, flavor components, and microbial community testing.

[0061] 2. Detection of Maotai-flavor Daqu

[0062] The sensory, physical and chemical indexes, pyrazine content and microbial community of the Maotai-flavor Daqu prepared in Experimental Examples 1 to 3 and the Comparative Example are compared as shown in Tables 1 to 4.

[0063] Table 1 Sensory results of Maotai-flavor Daqu obtained by different preparation methods

[0064]

[0065] As shown in Table 1, the sauce-flavored Daqu made from wheat and highland barley fermented powder has prominent sauce aroma, baking aroma, prominent fermented black bean aroma, and comfortable and pleasant aroma, and the overall sensory effect is better than that of the control example.

[0066] Table 2 Physical and chemical results of Maotai-flavor Daqu obtained by different preparation methods

[0067]

[0068] It can be seen from Table 2 that the physical and chemical indicators of the sauce-flavored Daqu made from wheat and highland barley fermented powder are normal.

[0069] Table 3 Results of the content of pyrazine substances in the sauce-flavored Daqu obtained by different preparation methods

[0070]

[0071]

[0072] As shown in Table 3, the sauce-flavored Daqu made from wheat and highland barley fermented powder greatly increased the content of tetramethylpyrazine, the main pyrazine substance in the Daqu, optimized the richness of the sauce-flavored flavor of the Sichuan sauce-flavored Daqu, and improved the overall quality of the sauce-flavored Daqu.

[0073] Table 4 Results of abundance (%) of the Maotai-flavor Daqu microbial community obtained by different preparation methods

[0074]

[0075] As shown in Table 4, the abundance of Scopulibacillus in the sauce-flavored Daqu made from wheat and highland barley fermented powder was significantly increased.

[0076] It can be seen from Tables 1 to 4 that the sauce-flavored Daqu prepared by the production process of the present invention can solve the problem of low abundance of Scopulibacillus in the Daqu in Sichuan sauce-flavored Daqu, overcome the microecological problems of the Daqu caused by the traditional Sichuan sauce-flavored Daqu preparation process and regional factors, and improve the quality of the sauce-flavored Daqu from the root.

Claims

1. A Maotai-flavor Daqu, characterized by: The koji-making raw materials include 50-100% of fermented highland barley powder and 0-50% of wheat flour by weight, and also include 38-42% of the total weight of the fermented highland barley powder and wheat flour, and 3-8% of the weight of mother koji powder.

2. The Maotai-flavor Daqu according to claim 1, characterized in that: The preparation method of highland barley fermented powder is as follows: adding water to highland barley raw grains to moisten the grains, and then piling the moistened materials; crushing the moistened highland barley to obtain highland barley powder; adding mother koji powder to mix evenly, and piling up for fermentation.

3. The Maotai-flavor Daqu according to claim 2, characterized in that: The method for preparing highland barley fermented powder satisfies at least one of the following conditions: The amount of water used for moistening grain is 8-20% of the mass of raw barley grain, and the time for piling and moistening is 6-12 hours; The fine powder of highland barley flour that can pass through a 1.2mm sieve hole accounts for 30-50%, and the whole grain highland barley does not exceed 5%; The amount of mother koji powder added is 3-8% of the mass of highland barley powder, and the stacking fermentation time is 6-24 hours.

4. The Maotai-flavor Daqu according to any one of claims 1 to 3, characterized in that: The preparation method of mother koji powder is as follows: the mature sauce-flavored koji stored for 3 to 8 months is crushed to a degree that the fine powder that can pass through a 1.2 mm sieve hole accounts for 60 to 80%.

5. The Maotai-flavor Daqu according to claim 1, characterized in that: The preparation method of wheat flour is as follows: adding water to the wheat raw grain to moisten the grain, and then piling the moistened material; crushing the moistened wheat to obtain wheat flour; The amount of water used for moistening the grain is 1-10% of the weight of the original wheat grain, and the grain is piled and moistened for 1-12 hours; The fine powder that can pass through the 1.2mm sieve of wheat flour accounts for 35-55%, and the whole wheat grains do not exceed 3%.

6. The method for preparing Maotai-flavor Daqu according to any one of claims 1 to 5, characterized in that: The specific steps include: (1) highland barley fermented powder and wheat flour are compounded to obtain a mixed powder, and then mother koji powder and grain moistening water are added to mix the material to obtain koji material; (2) The koji material is manually pressed or mechanically pressed according to the specifications of the large koji mold to form a koji blank; (3) The koji billets are transported to the fermentation room for koji placement and fermentation. The process control of the fermentation process is as follows: when the temperature rises to 60-65°C, the doors and windows are opened and the koji is turned over for the first time, and the humidity in the koji room is above 80%; when the temperature rises to 58-60°C after the first turning of the koji, the doors and windows are opened and the koji is turned over for the second time, and the humidity in the koji room is above 70%; when the temperature rises to 52-55°C after the second turning of the koji, the doors and windows are opened for ventilation and dehumidification; (4) After the fermentation of the koji is completed, the koji is disassembled and stored in a warehouse to obtain a sauce-flavored koji.

7. The method for preparing Maotai-flavor Daqu according to claim 6, characterized in that: In step (1), highland barley fermented powder accounts for 50-100% of the mass of the mixed powder, wheat flour accounts for 0-50% of the mass of the mixed powder, the added amount of mother koji powder is 3-8% of the mass of the wheat flour, and the added amount of grain moistening water is 38-42% of the mass of the mixed powder.

8. The method for preparing Maotai-flavor Daqu according to claim 6, characterized in that: In step (3), when the koji is settled, a layer of straw 15 to 30 cm thick is first laid in the fermentation room, and then the koji blanks are stacked in the koji room in an orderly manner of "three horizontally and three vertically"; and after each layer of koji blanks is laid, new and old straw and water are added for inoculation, heat preservation and moisture retention.

9. The method for preparing Maotai-flavor Daqu according to claim 6, characterized in that: In step (4), the fermentation time is 38 to 42 days, and the koji can be removed and stored when the moisture content of the koji drops to 15%.

10. The method for preparing Maotai-flavor Daqu according to claim 6, characterized in that: In step (4), the storage period of the koji is 3 to 6 months, and the moisture content of the finished koji is controlled below 13%.

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