A production process of a ceramic-fusion type low-temperature Daqu

Abstract

The present application relates to the technical field of liquor koji making, and discloses a production process of a ceramic-fusion type medium-low temperature Daqu, which is aimed at the pain points of high labor cost, large broken koji loss and destruction of stable metabolism of bacterial groups caused by high-frequency turning of traditional bacteria cultivation, and provides the following steps: quantitative grain moisturizing and stacking of raw materials; double-line differential crushing; mixing and pressing into koji base; laying a cushion layer in a room, arranging a reserved heat dissipation air duct at a set interval and covering a heat preservation object; and relying on adjustment of the covering object and the door and window to control the temperature during the bacteria cultivation period, and only performing a housing operation once in the whole cycle. The process successfully abandons the traditional 9 to 11 times of high-frequency turning of the koji, greatly reduces the labor and raw material loss, maintains the stable metabolism of microorganisms under low disturbance, and significantly improves the saccharifying power and quality of the finished koji.

Description

Technical Field

[0001] This invention belongs to the field of baijiu brewing and koji-making technology, and particularly relates to a ceramic-fusion type low-temperature koji production process. Background Technology

[0002] The existing traditional low-temperature Daqu (fermented rice starter) production process includes: simple screening of wheat raw materials, simple soaking, uniform particle size crushing, manual water mixing, manual or mechanical koji making, and indoor stacking. During the inoculum cultivation period, the starter is turned every 2-3 days, for a total of 9-11 turns throughout the cycle. Temperature control during turning is achieved manually by opening and closing doors and windows based on experience. Finally, sensory inspection and mixed storage are conducted. The characteristics of this conventional koji-making process are the lack of a standard rice husk padding layer for indoor placement, the limited temperature control methods (relying mainly on frequent turning to dissipate heat, balance temperature, and release moisture), the absence of a standard covering scheme, the lack of phased film covering and curtain covering for insulation and heat dissipation, and the absence of comprehensive sensory and physicochemical acceptance standards. The mixed storage of high-quality and low-quality starter leads to large fluctuations in physicochemical indicators.

[0003] Existing technologies have the following inherent defects and technical pain points:

[0004] Excessive turning of the koji (fermented starter culture) results in high labor costs and significant koji loss. A 28-day cultivation cycle requires turning the koji 9-11 times, each time necessitating the complete relocation and rearrangement of all koji blocks, leading to extremely high labor intensity. Frequent handling causes the surface mycelium of the koji to detach, resulting in 6-8% broken or damaged koji and raw material losses exceeding 10%.

[0005] Repeated turning of the koji disrupts the metabolism of the microbial community, resulting in significant fluctuations in the quality of the koji. Turning disturbs the stable microbial environment inside the koji, allowing foreign bacteria to easily enter the koji pile. It also alters the temperature, humidity, and oxygen supply of the koji, interrupting the continuous metabolic processes of molds, yeasts, and lactic acid bacteria. This leads to uneven coating thickness on the koji blocks, making it difficult to consistently match the batch-to-batch saccharification and fermentation power to the style of Tao Rong-type liquor. Furthermore, the existing medium-temperature koji process only achieves a saccharification power of 600-800, resulting in a low alcohol yield and koji aromas that are predominantly roasted and floral, which do not meet the requirements of baijiu brewing.

[0006] There is no standardized procedure for installing the incubator and covering it for incubation; heat dissipation relies entirely on turning the incubator. Because there are no fixed points for removing the covering, turning it over, and closing the chamber, the temperature at the incubator core often exceeds 52°C, resulting in the inactivation of a large number of aroma-producing fungi at low temperatures. Summary of the Invention

[0007] The purpose of this invention is to provide a ceramic-fusion type low-temperature Daqu production process to solve the above-mentioned problems.

[0008] This invention is implemented as follows: a ceramic-type low-temperature koji production process includes the following steps: S1. Moistening and stacking: Moistening the koji raw materials with water and stacking them in a sealed manner; S2. Differentiated crushing: The moistened raw materials are crushed independently on two crushing lines, and the ratio of fine powder to coarse powder is controlled; S3. Mixing and molding: The crushed raw materials are mixed with water and then pressed into koji blanks; S4. Placement in the koji room: A mat is laid on the floor of the incubation room, and the koji blanks are arranged according to the preset spacing between blanks and rows to form a reserved heat dissipation air duct, and the surface of the koji blanks is covered with an insulating material; S5. Incubation and single room closing: During the incubation period, the highest temperature in the koji room is limited, and the temperature is controlled by adjusting the insulating material and the opening of the doors and windows of the incubation room. Only one incubation operation is performed during the entire incubation period, and the low-temperature koji is obtained after the incubation is completed.

[0009] A further technical solution is provided in step S1: the raw material for making koji is pure wheat, or a mixture of wheat, barley and peas in a mass ratio of 70%; the amount of water added for moistening the grains accounts for 6% to 10% of the total weight of the raw materials for making koji; the water temperature for moistening the grains is room temperature or 40°C; the standing time for sealed stacking is 8 to 12 hours, and the moisture content of the wheat grains is controlled at 16%-18% after stacking.

[0010] A further technical solution is provided in step S1: the amount of water added for moistening the grains accounts for 8% of the total weight of the raw materials for making koji; the standing time for sealed stacking is 10h or 12h, and the moisture content of the wheat grains is controlled at 17% after the sealed stacking is completed.

[0011] A further technical solution is provided in step S2: the proportion of coarse skin that does not pass through a 20-mesh sieve after crushing is 65% to 75%, and the proportion of fine powder that passes through a 20-mesh sieve is 25% to 35%; the raw material for making koji is shaped like plum petals after crushing and has no intact wheat grains; in step S3: the final moisture content of the mixing is controlled to be 36% to 39%, and the water used for mixing is room temperature water or 25°C water; in the pressing and molding step, the koji blank is pressed into a size of 30×20cm with a thickness of 6.0cm to 6.5cm, and the weight of a single piece is about 5.0kg.

[0012] A further technical solution involves that, in step S2, the proportion of fine powder passing through a 20-mesh sieve is 30%; and in step S3, the final moisture content of the mixed material is controlled to be 38% to 38.5%.

[0013] A further technical solution, in step S4: the bedding layer includes a rice husk bedding layer with a thickness of about 5cm to 10cm, on which a wire mesh is laid, and the walls are surrounded by straw curtains; the arrangement of the koji blanks is: three arranged horizontally on both sides against the wall, and one arranged in the middle with the wind at the back; the spacing between the koji blanks is 3cm to 4cm, and the row spacing is 4cm to 6cm; during the koji installation process, diluted koji powder water is sprayed, and after the koji installation, the doors and windows are opened to air-dry the koji for 0.5h to 2h, and then a layer of woven strips and a layer of plastic strips are covered on the surface as the heat insulation covering.

[0014] A further technical solution involves the following temperature control procedures in step S5, prior to the curing process: Day 2: When the curing temperature reaches 35℃ to 38℃, remove the plastic film, open windows for ventilation for 2 hours, and retain the woven strips for insulation; Day 4: When the core temperature reaches 45℃ to 47℃, turn the woven strips over and appropriately widen the gaps in the curing blanks to equalize the temperature; Days 7-8: When the curing temperature reaches its peak, control the temperature by adjusting the opening of doors and windows and adding or removing outer coverings to ensure the temperature in the curing chamber remains ≤52℃ throughout the process; Days 14-15: ... The process involves combining four layers of mold cells, with the middle layer stacked in a herringbone pattern and the outer layer stacked at four top edges, leaving passageways around the perimeter. Insulation is achieved by wrapping the outer layer with two layers of woven strips, a layer of straw mat, a layer of plastic film, and an outer layer of straw mat, with the top covered with a seamless straw mat. After combining the mold cells, regular ventilation is required. When the temperature reaches 40℃ to 44℃, an additional layer of woven strips is added. When the temperature reaches 38℃ to 40℃, a plastic film is added to drain moisture from the center. The total incubation period is approximately 28 days. During the later stages of incubation, small windows are maintained for regular daily ventilation until the core of the mold is completely dry.

[0015] Further technical solutions also include step S6, finished product acceptance: taking the Daqu (fermented starter culture) after it leaves the room for physicochemical testing, with the following qualified standards: moisture ≤14%, acidity 0.4-0.8 mmol / 10g, saccharification power 600-1000 U / g, liquefaction power ≥1.0 U / g, and fermentation power 1.0-3.0 U / g.

[0016] Further technical solutions also include step S7, storage: the qualified koji is stored in the warehouse, and the koji blocks are stacked vertically in layers for a storage period of ≥3 months.

[0017] A further technical solution is that the storage period for warehousing is 3 to 6 months.

[0018] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0019] 1. Significantly reduced production costs: The entire culture cycle requires only one turning and closing operation, greatly reducing manual labor hours during the culture stage.

[0020] 2. Improved raw material utilization: The mycelium on the surface of the koji cake is less likely to fall off, and the proportion of broken and damaged koji cakes has decreased from 12.6% to 2.1%, resulting in a 10.5% increase in raw material utilization.

[0021] 3. Overall improvement in product quality: The batch fluctuation coefficients of saccharification power and fermentation power have been reduced from the traditional 17%–23% to ≤4.5%; the defect rate of rancidity and skin peeling has been reduced from 19.2% to less than 2.5%. The saccharification power of the cultivated medium- and low-temperature koji reaches 800-1000, increasing the alcohol yield, and the koji aroma is mainly grain aroma.

[0022] 4. Stable microbial growth and metabolism: The temperature is kept below 52℃, which keeps the microbial community in a stable symbiotic metabolic stage, efficiently producing the required enzymes and flavor precursors. Attached Figure Description

[0023] Figure 1 A flow chart of a ceramic-fused medium-low temperature koji production process is provided by the present invention.

[0024] Figure 2 This is a schematic diagram of the installation of ceramic-type low-temperature koji in a room, provided by the present invention.

[0025] Figure 3 A schematic diagram of the heat dissipation air duct of the Taorong type medium and low temperature Daqu provided by the present invention;

[0026] Figure 4 This is a schematic diagram of the stacking layout of Taorong-type low-temperature Daqu (a type of starter culture) provided by the present invention. Detailed Implementation

[0027] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0028] The technical principle of this invention is as follows:

[0029] The principle of balanced substrate heat control: multi-stage impurity removal and purification of raw materials, precise seasonal grain moistening and double-line crushing, so that the moisture and air permeability of the koji blank are highly uniform, eliminating local extreme heat accumulation and greatly reducing the heat dissipation requirements of turning and koji.

[0030] Standardized airflow cooling principle: The four-sided installation process unifies the thickness of the rice husk and the spacing of the rice cakes to form a stable cooling airflow. Combined with staged film covering and curtain covering for buffering and temperature regulation, the temperature is balanced by the surrounding cover, eliminating the need to move the rice cake blocks multiple times.

[0031] Precise temperature control principle: During the heating period, the gap-opening operation is combined with the adjustment of doors and windows to regulate the temperature of the gaps in the curly pile, so that the subsequent microbial community enters a stable symbiotic metabolic stage.

[0032] The principle of stable metabolism of low-disturbance microbial community: Only one turning and mixing of the fermentation chamber is required throughout the entire process, avoiding the introduction of contaminants by frequent turning, so that molds, yeasts and lactic acid bacteria can continuously and stably produce enzymes and generate flavor precursors.

[0033] (I) Standard Process General Implementation Procedures and Technical Details

[0034] The specific production process of the ceramic-fused low-temperature Daqu (a type of starter culture) of this invention includes the following general steps and operating procedures:

[0035] Step 1: Raw material selection and impurity removal

[0036] Purpose of the operation: To ensure the basic quality of the raw materials for making koji, remove stones, metal impurities, and dust, purify the raw materials, and reduce the introduction of miscellaneous bacteria from moldy and insect-infested raw materials.

[0037] Raw materials and equipment: Pure wheat, meeting or exceeding the national standard grade II, requiring plump grains free from mold, sprouting, insect infestation, and impurities. Raw material sorting and screening machines, dust removal and impurity removal air separation equipment, and magnetic separators are employed. Before entering the warehouse, the raw materials continuously undergo air separation for dust removal, magnetic separation for iron removal, and screening for stone removal to ensure cleanliness and the absence of foreign matter.

[0038] Step 2: Moisten the grain and pile it up

[0039] Purpose of the operation: To soften the wheat grains, making their surface soft and their interior firm, so as to make them suitable for subsequent crushing and shaping, balance the basic moisture of the koji blanks, and reduce localized damp heat accumulation.

[0040] Equipment and auxiliary materials: Automated grain moistening equipment, with natural spring water as the auxiliary material.

[0041] Operating procedure: The raw materials are evenly sprayed with clean water, stirred by an auger, and then stored in a sealed silo. The moisture content used for moistening the grains is approximately 6-10% (preferably 8%) of the total weight of the raw materials; the standing time is approximately 8-12 hours (preferably 12 hours); after stacking, the moisture content of the wheat grains is controlled at 16%-18% (preferably 17%).

[0042] Key control point: In summer, the moisture content of the grain should not exceed 10% to avoid anaerobic heat accumulation in the koji mold later and reduce the pressure on heat dissipation during turning. This step is based on the principle of balanced substrate heat control, and precise grain moistening according to the season ensures uniform moisture content in the koji mold, reducing localized extreme heat accumulation from the source.

[0043] Step 3: Differentiated Dual-Line Crushing

[0044] Operational objective: To precisely control the porosity and air permeability of the koji blanks, to match the stacking density with the particle size difference between the two production lines, to balance the oxygen and heat conduction inside the koji stacks, and to support the subsequent cultivation mode of turning the koji blanks over only once.

[0045] Equipment: Double roller crusher, 20-mesh grading vibrating screen.

[0046] Operating methods and parameters: After the raw materials are moistened, they are pulverized and screened independently on two separate pulverizing lines. The proportion of fine powder passing through a 20-mesh sieve is 25%-35% (preferably 30%); the pulverization standard is that the core is rotten but the husk is intact, resembling plum petals, with no whole wheat grains.

[0047] Step 4: Add water and mix

[0048] Purpose of the operation: To regulate the moisture content of the koji blanks during molding, to unify the water retention capacity of the koji blanks, and to reduce uneven moisture and heat distribution.

[0049] Equipment: Horizontal continuous mixing machine.

[0050] Operating method and parameters: Add room temperature water, and control the moisture content of the mixture at 36%-39% (preferably 38-38.5%). The standard for operation is that the mixture should be free of ash sacs and lumps, and should be able to be formed into a ball by hand and not stick to the hand when released.

[0051] Step 5: Pressing and manipulating the melody

[0052] Operational objective: To standardize the molding process, unify the specifications and density of the koji blanks, and ensure consistent heat storage and dissipation performance of the koji blanks in the same stack.

[0053] Equipment: Fully automatic koji-making machine, koji-transfer and transport vehicle.

[0054] Operating method and parameters: The mixed materials are fed into the koji-making machine for continuous pressing and shaping. After cleaning the edges and leftover materials, they are neatly stacked and transported to the incubation room by a transfer vehicle. The koji blanks are 30×20cm in size, 6.0-6.5cm thick, and weigh approximately 5.0kg each.

[0055] Step 6: Installation of the curved surface (four-sided process)

[0056] Operational objective: To standardize the thickness and spacing of rice husks, and to construct a stable and uniform heat dissipation channel based on physical layout, thereby dispersing the heat of the rice husk pile. This, combined with subsequent staged film coating and temperature adjustment, eliminates the need to move the rice husk blocks multiple times (standardized airflow heat dissipation principle).

[0057] Auxiliary materials and temperature measurement: rice husks, wire mesh, straw mats, woven strips, plastic strips, and diluted koji powder water. Multiple temperature measurement points are used between the three koji sections and at the core of the koji.

[0058] Operating parameters: The ground is covered with a rice husk layer approximately 5-10cm thick, topped with wire mesh, and the walls are lined with straw mats. The koji blocks are arranged with three blocks against the walls on each side and one in the middle facing the wind, with a spacing of 3-4cm between blocks and a row spacing of 4-6cm. Each room holds 3 tons of koji, employing a "simultaneous installation, spraying, drying, and opening" four-sided process. Diluted koji powder is sprayed twice during koji transport and installation. In summer, after installation, the doors and windows are opened to allow the koji to air dry for 1-2 hours. The surface is covered with one layer of woven strips and one layer of plastic strips; exposed koji blocks are strictly prohibited.

[0059] Step 7: Incubation and single-time turning of the mold in the room

[0060] Control red line: The temperature in the curing room is ≤52℃ throughout the entire process. Temperature is controlled by coverings and the opening of doors and windows. Only one turning and closing operation is performed during the entire 28-day incubation cycle. This is the core embodiment of the principle of precise temperature control and the principle of stable metabolism of low-disturbance microbial community. It can avoid the introduction of miscellaneous bacteria by frequent turning and ensure that mold and other fungi continuously and stably produce enzymes.

[0061] Temperature control process:

[0062] 1. Day 2 after moving in: Temperature 35-38℃, remove the plastic film, open the windows for ventilation for 2 hours during the day; rely on the woven strips for insulation and heat buffering.

[0063] 2. Days 3-4 after entering the room: When the core temperature reaches 45-47℃, turn the woven strips over and appropriately widen the gaps in the blank to balance the internal temperature.

[0064] 3. 7-8 days after entering the room: Increase to peak temperature, adjust the opening of doors and windows and the outer covering to control the temperature.

[0065] 4. Days 10-15 after moving in: On day 10, doors and windows are basically closed; on day 14, only a small window of 2-5cm is left open; on day 15, the room-sharing procedure is carried out.

[0066] 5. Building specifications: One floor is combined with four floors, with the middle layer stacked in a herringbone pattern and the outer layer stacked at four top edges, with a road reserved around the perimeter. The outer layer consists of two layers of woven strips, one layer of straw mat, one layer of plastic film, and another layer of straw mat. The top is covered with straw mat without gaps.

[0067] 6. After the room is assembled: Ventilate periodically for short periods. When the temperature of the refractory core is 40-43℃, cover it with a layer of woven strips. When the temperature is 38-40℃, cover it with plastic film as needed to drain moisture. Keep a small window open for daily ventilation until the refractory core is completely dry before leaving the room.

[0068] Step 8: Finished Product Inspection and Warehousing

[0069] Acceptance criteria: Five-point sampling method for each batch. Sensory requirements: pure aroma, intact coating, white / grayish-white mycelium on the cross-section, and no off-odor. Physicochemical standards: moisture ≤14%, acidity 0.4-0.8 mmol / 10g, saccharification power 600-1000 U / g, liquefaction power ≥1.0 U / g, fermentation power 1.0-3.0 U / g.

[0070] Storage conditions: The warehouse should be dry, well-ventilated and free from pollution. The storage period should be ≥3 months (preferably 3-6 months). The koji blocks should be stacked vertically in layers to mature and enrich flavor precursors before being used in baijiu brewing.

[0071] (II) Comparison of experimental data between the examples and comparative examples

[0072] To verify the actual effectiveness of the above process, the following comparative tests were conducted. All examples and comparative examples were conducted under the same basic conditions: equipped with a dust removal unit, a dual-line crusher, a horizontal mixing machine, a fully automatic koji-making machine, a culture room, and a ventilated storage warehouse. No special functional microbial groups were added to any of the test groups; only high-quality microbial strains used during the culture process were employed. Relevant physicochemical index tests were performed according to the "QB / T4257-2011 General Analytical Methods for Brewing Koji".

[0073] Example 1 (Standard complete process, only 1 turning and joining)

[0074] 1. Ingredient ratio: pure wheat, sweet spring water.

[0075] 2. Complete process steps and parameters:

[0076] Raw materials are carefully selected (not lower than national standard grade II) and undergo multi-stage impurity and dust removal. The grain is moistened with 8.0% moisture at room temperature, piled for 12 hours, resulting in an output moisture content of 16.5%. Double-line crushing: No. 2 line has a fineness ratio of 70:30, and No. 3 line has a fineness ratio of 75:25. Water is added and mixed to achieve a final moisture content of 38%. The pressed koji size is 30×20×6.5cm, with each piece weighing approximately 5kg. The koji is installed on four sides: a 10cm layer of rice husks, 3cm spacing between koji pieces, two sprays of koji powder water, and dried for 1.5 hours. The top layer is covered with woven strips and a layer of plastic sheeting; each chamber holds 3 tons.

[0077] 28-day phased temperature-controlled incubation: On the second day after entering the curing chamber, maintain a temperature of 35-38℃, remove the plastic film, and ventilate for 2 hours during the day. On the fourth day, when the core temperature reaches 44-45℃, turn the woven strips over and widen the gaps in the curing blank. On the seventh and eighth days, adjust the doors, windows, and coverings to control the temperature. On the fourteenth day, leave only a small window of 2-5cm and perform the chamber closure operation (one layer closure for four layers). After closure, add another layer of woven strips when the core temperature reaches 41-44℃, and add plastic film as needed when the temperature reaches 38-40℃. The total cycle is 28 days until the core is completely dry.

[0078] 3. Acceptance results: Moisture content 11.3%, acidity 0.52 mmol / 10g, saccharification power 930 U / g, liquefaction power 2.0 U / g, fermentation power 2.3 U / g; stored for 4 months.

[0079] Example 2 (Replacement of raw materials)

[0080] 1. Raw material ratio: Wheat, barley, and peas in a mass ratio of 7:2:1; spring water.

[0081] 2. Complete process steps and parameters:

[0082] The grain moisture content was 8.0% (room temperature water), and after piling for 12 hours, the output moisture content was 16.9%. The coarse-to-fine grinding ratio was the same as in Example 1. The final moisture content of the mixed materials was 38.4%. The pressing specifications were the same as in Example 1. For the four-sided curing: a 10cm layer of rice husks was used as a base, spaced 3cm apart, and the curing powder was sprayed twice. The curing was then allowed to dry for 1.5 hours. On the second day after entering the curing chamber, the curing temperature was 37-40℃; on the fourth day, the curing core temperature was 46-49℃, the woven strips were turned over and the seams were tightened; on the 15th day, the chamber was closed. After closure, when the curing temperature was 42-45℃, the woven strips were added as needed; when the temperature was 37-41℃, plastic film was added as required.

[0083] 3. Acceptance results: Moisture content 12.1%, acidity 0.58 mmol / 10g, saccharification power 906 U / g, liquefaction power 1.5 U / g, fermentation power 1.9 U / g; stored for 4 months.

[0084] Example 3 (Optimized Grain Moistening Parameters)

[0085] 1. Ingredient ratio: pure wheat, sweet spring water.

[0086] 2. Complete process steps and parameters:

[0087] The grain moisture content was 8.0% at 40℃, and after piling for 10 hours, the output moisture content was 17.2%. The crushing and pressing specifications were the same as in Example 1. The final moisture content of the mixed materials was 38%. The koji preparation and drying process for 1.5 hours was the same as in Example 1. On the second day after entering the fermentation chamber, the koji temperature was 35-38℃; on the fourth day, the koji core temperature was 44-46℃, and gaps were opened; on the 15th day, the fermentation chamber was closed. After closure, at a koji temperature of 41-42℃, woven strips were added; at 38-41℃, plastic film was added.

[0088] 3. Acceptance results: Moisture content 11.8%, acidity 0.72 mmol / 10g, saccharification power 882 U / g, liquefaction power 1.7 U / g, fermentation power 2.1 U / g; stored for 4 months.

[0089] Example 4 (Lower Boundary Parameter Combination and Cooperative Control)

[0090] This embodiment mainly verifies the feasibility of the process under the combination of lower boundary parameters such as lower moisture content and shorter drying time.

[0091] Ingredient ratio: pure wheat, room temperature spring water.

[0092] Complete process steps and parameters:

[0093] Moistening and grinding: The moisture content of the moistened grain is controlled at 6%, and the sealed stacking time is 8 hours, with an output moisture content of about 16%. Due to the low moisture content of the moistened grain, the proportion of fine powder is increased during the double-line grinding to ensure the adhesion of the koji blanks, and the proportion of fine powder passing through a 20-mesh sieve is adjusted to 35%.

[0094] Mixing and pressing: The final moisture content of the mixed materials should be controlled at 36%, using room temperature water. The pressing dimensions are 30×20×6.0cm.

[0095] Four-sided koji installation: A 5cm layer of rice husks is used as a base. Due to the low initial moisture content of the koji blanks, the spacing between the blanks is set to 3cm, and the row spacing is set to 4cm to facilitate heat and moisture retention. After spraying diluted koji powder water, the drying time is shortened to 0.5 hours to avoid excessive loss of surface moisture; then, woven strips and plastic sheeting are used for covering.

[0096] Temperature-controlled incubation: On the second day after entering the incubator, the temperature should be 35-38℃; on the fourth day, when the core temperature reaches 45℃, turn the braided strips over and sew them together; on the 14th day, perform the incubator closure operation. The temperature control logic after closure is the same as in Example 1, with a total cycle of approximately 28 days.

[0097] Acceptance results: Moisture 10.5%, acidity 0.45 mmol / 10g, saccharification power 820 U / g, liquefaction power 1.6 U / g, fermentation power 1.8 U / g.

[0098] Conclusion: With extremely low moisture content in the grains and mixing materials (6% and 36%) and an air-drying time of only 0.5 hours, by increasing the proportion of fine powder (35%) and reducing the spacing between the koji blanks, moisture and heat were effectively locked in, and the koji formation indicators were still comprehensively superior to those of the traditional process.

[0099] Example 5 (Upper Boundary Parameter Combination and Cooperative Control)

[0100] This embodiment mainly verifies the feasibility of the process under the combination of upper boundary parameters such as high moisture content and long drying time, and overcomes the problem of uneven heating caused by a single high moisture content (such as Comparative Example 1).

[0101] Ingredient ratio: 70% wheat, 20% barley, 10% peas, and spring water.

[0102] Complete process steps and parameters:

[0103] Moistening and Grinding: The moisture content of the moistened grain is adjusted to 10%. To ensure that the high moisture content penetrates fully and evenly, 40℃ warm water is used for moistening, and the sealed stacking time is extended to 12 hours, resulting in an output moisture content of approximately 18%. To address the reduced air permeability caused by high moisture content, the proportion of fine powder is reduced during grinding, with the proportion of fine powder passing through a 20-mesh sieve decreasing to 25%.

[0104] Mixing and pressing: The final moisture content of the mixed materials is controlled at 39%, and water at 25℃ is used. The pressing dimensions are 30×20×6.5cm.

[0105] Four-sided installation: 10cm rice husk layer. To address the issue of heat accumulation and overheating in high-moisture koji blanks, the heat dissipation air ducts were enlarged, and the spacing between koji blanks was set to 4cm, and the row spacing to 6cm. After spraying koji powder water, the koji was allowed to air dry for 2 hours with open doors and windows to dissipate excess surface moisture; then it was covered with woven strips and plastic sheeting.

[0106] Temperature-controlled incubation: On the second day after entering the chamber, the temperature of the refractory material steadily rose to 36-38℃ (without the slow temperature rise seen in Comparative Example 1); on the fourth day, when the core temperature reached 47℃, the refractory material was turned over and the seams were closed; on the fifteenth day, the chamber was closed. The temperature control logic after closure was the same as in Example 1.

[0107] Acceptance results: Moisture content 12.8%, acidity 0.75 mmol / 10g, saccharification power 890 U / g, liquefaction power 1.9 U / g, fermentation power 2.5 U / g.

[0108] Conclusion: When the moisture content of the grain is as high as 10%, by using 40℃ water temperature to enhance penetration, reducing the proportion of fine powder (25%) to improve air permeability, increasing the spacing between koji blanks (4cm / 6cm), and extending the drying time (2h), the defects of "suffocation and sourness and a sharp drop in saccharification power" in Comparative Example 1 were successfully avoided, ensuring high fermentation power and high enzyme yield under high moisture conditions.

[0109] Comparative Example 1 (Unoptimized Lubricant)

[0110] The raw material ratio is pure wheat and spring water. The grain is moistened with 10% moisture, piled for 10 hours, and the output moisture content is 17.9%. Crushing, mixing (38%), pressing, and placing the koji (with a 10cm layer of rice husks as a base, and drying for 1.5 hours) are the same as in Example 1. On the second day after entering the fermentation chamber, the koji temperature is only 34-36℃; on the fourth day, when the core temperature is only 41-43℃, the woven strips are turned over. The chamber is closed on the 16th day. Temperature control after closure is the same as in Example 1, with a total cycle of approximately 30 days.

[0111] Acceptance results: Moisture content 12.9%, acidity 0.72 mmol / 10g, saccharification power 702 U / g, liquefaction power 1.5 U / g, fermentation power 1.8 U / g.

[0112] Comparative Example 2 (lack of standardized amprolium)

[0113] The raw material ratio is pure wheat and spring water. The moisture content of the soaked grain is 9.0%, and after piling for 10 hours, the moisture content of the output is 17.9%. The crushing, mixing, and pressing of the koji are the same as in Example 1. The koji-making process is changed to: the rice husk layer is only 3cm thick, the koji powder is sprinkled, and the koji is dried for only 0.5 hours. On the second day after entering the fermentation chamber, the koji temperature is 34-36℃; on the fourth day, the core temperature is 44-47℃, and the koji blanks show signs of tilting and sticking; the chamber is closed on the 16th day. The total cycle is approximately 28 days.

[0114] Acceptance results: Moisture 13.2%, acidity 0.7 mmol / 10g, saccharification power 678 U / g, liquefaction power 1.3 U / g, fermentation power 1.77 U / g.

[0115] Comparative Example 3 (Traditional Low-Temperature Kernel Production Process)

[0116] Ingredient ratio: 60% barley, 40% peas.

[0117] Use room temperature cool water (≤40℃) to moisten the grains, grind them into coarse to fine powder at a ratio of 6:4, and achieve a final moisture content of 36-39%. Place the koji (fermented starter culture) in the room: pre-set the room temperature to 22-24℃, place the koji blanks upright with a spacing of 3-5cm, and control the initial humidity at 65-70%. Temperature-controlled incubation: During the mold-drying period (1-3 days), maintain the koji temperature at 24-26℃; during the mycelial growth period (5-7 days), the temperature of the koji blanks must not exceed 30℃. Check every 1-2 days and frequently turn the koji when heating up, changing the inside out and the bottom out, for a total of 9-11 turns throughout the process; during the post-maturation (8-12 days), slowly lower the temperature to 25-27℃ and reduce the humidity to around 60%.

[0118] Acceptance results: Moisture 12.1%, acidity 0.6 mmol / 10g, saccharification power 816 U / g, liquefaction power 1.4 U / g, fermentation power 1.81 U / g.

[0119] Analysis of experimental test statistical results

[0120] The table below shows a comparison of relevant indicators between the examples and the comparative examples of Daqu production. The relevant indicators were tested according to "QB / T4257-2011 General Analytical Methods for Brewing Daqu".

[0121] Moisture (%) Acidity (mmol / 10g) Glycochemical power (U / g) Liquefaction power (U / g) Fermentation power (U / g) Example 1 11.3 0.52 930 2.0 2.3 Example 2 12.1 0.58 906 1.5 1.9 Example 3 11.8 0.72 882 1.7 2.1 Comparative Example 1 12.9 0.72 750 1.5 1.8 Comparative Example 2 13.2 0.7 756 1.3 1.77 Comparative Example 3 12.1 0.6 816 1.4 1.81

[0122] Based on the data from the above embodiments and comparative examples, it can be concluded that:

[0123] 1. Comparison of Example 1 and Comparative Example 1: Comparative Example 1 increased the moisture content of the soaking material and shortened the soaking time, resulting in uneven heating of the koji blanks, weak microbial growth and metabolism during the cultivation process, and a significant decrease in the sensory score and physicochemical indicators of the finished koji blanks; while Example 1 ensured appropriate moisture content of the koji blanks by timely and quantitative soaking and stacking.

[0124] 2. Comparison of Example 1 and Comparative Example 2: Comparative Example 2 lacked a standardized incubation and fermentation procedure, resulting in a 15% reduction in mold growth on the fermented koji during the cultivation period, leading to poor sensory quality. Example 1 employed a standardized four-sided fermentation procedure, with the fermented koji arranged in an orderly and comfortable manner and with ventilation channels for heat dissipation. Combined with two sprays of koji powder water and an extended drying time, this resulted in better normal growth and reproduction of microorganisms compared to Comparative Example 2.

[0125] 3. Comparison of Example 1 and Comparative Example 3: Comparative Example 3 uses the traditional low-temperature curing process, with up to 9-11 times of curing time, and the manual labor time is about 10 times that of Example 1. The breakage rate of the curing blocks is about 19.5%, and the proportion of defective curing blocks is about 18%. Its overall effect is far lower than that of Example 1.

[0126] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A ceramic-fusion type low-temperature Daqu (a type of starter culture) production process, characterized in that, Includes the following steps: S1. Soaking and stacking: Soak the raw materials for making koji with water and then stack them in a sealed container; S2. Differentiated grinding: The raw materials after soaking are ground independently on two grinding lines, and the ratio of fine powder to coarse bran is controlled. S3. Mixing and shaping: The crushed raw materials are mixed with water and then pressed into shaped blanks; S4. Placement of koji in the room: Lay a mat on the floor of the culture room, arrange the koji blanks according to the preset koji blank spacing and row spacing to form a reserved heat dissipation air duct, and cover the surface of the koji blanks with heat insulation material; S5. Cultivation and Single Room Combination: During the cultivation cycle, the highest temperature in the fermentation room is limited. Temperature is controlled by adjusting the insulation covering and the opening of the doors and windows of the cultivation room. The fermentation room is combined and turned over only once during the entire cultivation cycle. After the cultivation is completed, the medium-low temperature fermented koji is obtained immediately upon exiting the room.

2. The ceramic-fusion type low-temperature Daqu production process according to claim 1, characterized in that, In step S1: the raw material for making koji is pure wheat, or a mixture of wheat, barley and peas in a mass ratio of 70%; The amount of water used for soaking the grains accounts for 6% to 10% of the total weight of the raw materials used for making koji; the water temperature for soaking the grains is room temperature or 40℃; The static standing time for sealed stacking is 8 to 12 hours. After stacking, the moisture content of the wheat grains is controlled at 16%-18%.

3. The ceramic-fusion type low-temperature Daqu production process according to claim 1, characterized in that, In step S1: the amount of water used for soaking the grains accounts for 8% of the total weight of the raw materials used for making koji; The static time for sealed stacking is 10h or 12h, and the moisture content of the wheat grains is controlled at 17% after the sealed stacking is completed.

4. The ceramic-fusion type low-temperature Daqu production process according to claim 1, characterized in that, In step S2: the proportion of coarse skin that does not pass through a 20-mesh sieve after pulverization is 65% to 75%, and the proportion of fine powder that passes through a 20-mesh sieve is 25% to 35%; The raw materials for making koji are crushed into the shape of plum petals and contain no whole wheat grains; In step S3: control the final moisture content of the mixed material to be 36% to 39%, and use room temperature water or 25°C water for mixing; In the pressing and molding step, the blank is pressed into a size of 30×20cm with a thickness of 6.0cm to 6.5cm, and the weight of a single piece is about 5.0kg.

5. The ceramic-fusion type low-temperature Daqu production process according to claim 4, characterized in that, In step S2, the proportion of fine powder passing through a 20-mesh sieve is 30%. In step S3, the final moisture content of the mixed material is controlled to be 38% to 38.5%.

6. The ceramic-fusion type low-temperature Daqu production process according to claim 1, characterized in that, In step S4: the bedding layer includes a rice husk bedding layer with a thickness of about 5cm to 10cm, on which a wire mesh is laid and the walls are surrounded by straw curtains; The arrangement of the blanks is as follows: three blanks are arranged horizontally on both sides against the wall, and one blank is arranged in the middle with the wind at the back; the spacing between blanks is 3cm to 4cm, and the row spacing is 4cm to 6cm. During the curing process, diluted curing powder is sprayed with water, and after curing, doors and windows are opened to allow the curing to air dry for 0.5 to 2 hours. Then, a layer of woven strips and a layer of plastic strips are placed on the surface as the heat-insulating covering.

7. The ceramic-fusion type low-temperature Daqu production process according to claim 1, characterized in that, In step S5, the following temperature control procedures are performed before the room closure operation: Day 2 after moving in: When the temperature rises to 35℃ to 38℃, remove the plastic film, open the windows for ventilation for 2 hours, and leave the woven strips for insulation; Day 4 after entering the room: When the core temperature reaches 45℃ to 47℃, turn the woven strips over and appropriately widen the gaps in the blank to equalize the temperature; Days 7 to 8 after entering the room: The temperature rises to its peak. Temperature is controlled by adjusting the opening of doors and windows and adding or removing outer coverings to ensure that the temperature in the room is ≤52℃ throughout the entire process. The room merging operation will be carried out on the 14th to 15th day after moving in; the room merging stacking method is one layer to four layers, the middle layer is stacked in a herringbone shape, the outer layer is stacked at the top of the four, and passageways are reserved around the perimeter; The insulation wrapping method consists of wrapping the outer layer with two layers of woven strips, a layer of straw mat, a layer of plastic film, and an outer layer of straw mat, with the top covered with straw mat without gaps; After the mold is assembled: open the windows for ventilation regularly. When the temperature of the mold is between 40℃ and 44℃, add a layer of woven strips. When the temperature of the mold is between 38℃ and 40℃, add a plastic film to drain the moisture from the center. The total incubation period is about 28 days. In the later stage of incubation, keep the small windows open for ventilation every day until the mold core is completely dry.

8. The ceramic-melting type low-temperature Daqu production process according to any one of claims 1-7, characterized in that, It also includes step S6, finished product acceptance: Take the Daqu (fermented starter culture) after it leaves the room and conduct physicochemical tests. The qualified standards are: moisture ≤14%, acidity 0.4-0.8mmol / 10g, saccharification power 600-1000 U / g, liquefaction power ≥1.0 U / g, and fermentation power 1.0-3.0 U / g.

9. The ceramic-melting type low-temperature Daqu production process according to any one of claims 1-7, characterized in that, It also includes step S7, storage: the qualified koji is stored in the warehouse, the koji blocks are stacked vertically in layers, and the storage period is ≥3 months.

10. The ceramic-melting type low-temperature Daqu production process according to claim 9, characterized in that, The storage period for the goods is 3 to 6 months.

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