Manual craft brewing method of solid-state-method Daqu Fen-flavor five-grain Baijiu

Abstract

The invention discloses a manual craft brewing method of solid-state-process Daqu Fen-flavor five-grain liquor, and relates to the technical field of liquor brewing. According to the method, red tassel sorghum, northeast sorghum, black tartary buckwheat, coix seeds and mung beans are used as raw materials, and the processes of raw material inspection and pretreatment, accurate grain soaking according to grains, gradient grain steaming according to grains, double-stage inoculation and bacterium cultivation, mixing and low-temperature cellar fermentation, temperature-controlled and speed-controlled distillation, whole-process sanitary cleaning, process management and control and the like are sequentially carried out on the red tassel sorghum, the northeast sorghum, the black tartary buckwheat, the coix seeds and the mung beans. According to the difference of physicochemical properties such as skin thickness, water absorption and heat resistance of five kinds of grains, key parameters such as grain soaking water temperature (15-75 DEG C), grain steaming duration (primary steaming 20-30 min + secondary steaming 30-40 min), inoculation temperature (18-35 DEG C) and the like are individually set, and meanwhile, an integrated process system of grain separation treatment, precise parameter control, low-temperature fermentation and standard distillation is established. The technical problems of non-uniform gelatinization, uncoordinated fermentation and large flavor fluctuation caused by mixing treatment in traditional five-grain brewing are solved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of liquor brewing, in particular to a solid-state method of hand-crafting baijiu (a Chinese liquor) with five grains using Daqu (a type of Chinese liquor starter) and a clear fragrance, which is based on five raw materials, i.e., Hongyingzi sorghum, Northeastern sorghum, black bitter buckwheat, Job's tears, and green beans. BACKGROUND

[0002] Solid-state method of Daqu clear fragrance baijiu occupies an important market share due to its flavor characteristics of “pure and clear fragrance, mellow and sweet taste, and long-lasting aftertaste”. Five-grain baijiu, which is made by combining the nutritional ingredients (such as starch from sorghum, bioflavonoids from bitter buckwheat, and vitamins from green beans) and flavor substances of multiple grains, has a richer taste and more balanced nutrition, and becomes an important category of high-end hand-crafted baijiu.

[0003] However, the existing hand-crafting technology of five-grain baijiu has significant defects: Raw material processing is rough: the existing technology mostly adopts the “mixed grain soaking and mixed grain steaming” mode (e.g.,, but the physicochemical properties of the five grains, such as Hongyingzi sorghum (thick skin, poor water absorption) and green beans (thin skin, easy to gelatinize), are quite different, and mixed processing leads to over-gelatinization of some grains (such as green beans) and under-gelatinization of some grains (such as Hongyingzi sorghum), which directly affects the subsequent fermentation efficiency; Key parameters are vague: core parameters such as soaking water temperature, steaming time, and inoculation temperature lack personalized settings and mostly use unified standards, leading to uneven microbial inoculation and uncoordinated fermentation process, and large fluctuations in the flavor of the raw liquor (coefficient of variation of total ester content ≥20%); Process specification is insufficient: hand-crafting relies on the experience of operators, and there is a lack of standardized processes in aspects such as sanitary cleaning, fermentation sealing, and distillation control, which leads to a high risk of contamination by miscellaneous bacteria and a low pass rate of raw liquor; Quality stability is poor: due to the above problems, the quality of existing five-grain hand-crafted baijiu varies significantly between batches, and the taste consistency is poor, which makes it difficult to meet the quality requirements of consumers for high-end baijiu.

[0004] Therefore, there is an urgent need for a hand-crafting method that can combine the physicochemical properties of the five grains, achieve precise parameter control, and implement standardized operations, to solve the core problems of existing technology. SUMMARY

[0005] Technical problems to be solved The present application aims to overcome the technical problems of “mixed processing leading to uneven gelatinization, vague parameters leading to uncoordinated fermentation, and non-standardized process leading to quality fluctuations” in the hand-crafting of five-grain baijiu, and to provide a precise, standardized, and lean solid-state method of hand-crafting baijiu with five grains using Daqu and a clear fragrance.

[0006] Technical solution To achieve the above object, the application adopts the following technical solutions: A solid-state method of hand-craft fine brewing of Luzhou-flavor five-grain baijiu, comprising eight steps of raw material inspection and pretreatment, grain separation and precise grain soaking, grain separation and gradient steaming, two-stage inoculation and bacteria cultivation, mixed low-temperature pit entry fermentation, temperature and speed controlled distillation, whole-process sanitary cleaning and process control, the core design of each step is as follows: Raw material inspection and pretreatment: Focus on "source quality control", strictly remove unqualified raw materials through sensory inspection, avoid the influence of factors such as moldy change and impurities on the quality of raw liquor, and lay a foundation for subsequent processes.

[0007] Grain separation and precise grain soaking: Adopt the grain separation treatment mode of "one grain one pot", according to the differences in the skin thickness and water absorption of the five kinds of grains, individualize the setting of grain soaking water temperature (red yang highland barley 70℃, northeast highland barley 75℃, etc.) and water level (30-80 centimeters, adjusted according to grain types), solve the problem of "some grains are soaked through, some are undercooked" caused by mixed grain soaking; Make clear the seasonal difference of soaking time (15-18 hours in cold season, 10-13 hours in hot season), and ensure the soaking effect and raw material utilization rate through "stirring and removing impurities in soaking water" and "leakage inspection of grain leakage".

[0008] Grain separation and gradient steaming: Design the gradient steaming process of "initial steaming - soaking - re-steaming - open steaming", initial steaming realizes preliminary gelatinization of grains, soaking ensures uniform penetration of water, re-steaming completes deep gelatinization, and open steaming removes excess water and disinfects; Accurately set the initial steaming time (20-30 minutes) and re-steaming time (30-40 minutes) according to grain types, and make clear the quantitative indicators of steamed grains (opening rate ≥90%, turning flower ≤5%), to ensure the consistency of gelatinization effect.

[0009] Two-stage inoculation and bacteria cultivation: Innovate the airing bed treatment method of "first air blowing sterilization, then air blowing cooling", to reduce the pollution of miscellaneous bacteria; Adjust the inoculation temperature and frequency based on room temperature, set the temperature according to the differences in grain types in cold season, use a unified gradient at room temperature 10-20℃, to ensure the stability of the activity of microorganisms (mold, yeast, etc.) in Daqu, and provide protection for the generation of flavor substances in the fermentation process.

[0010] Mixed low-temperature pit entry fermentation: Strictly follow the principle of "low-temperature pit entry, fast loading, low-temperature fermentation", limit the pit entry time (≤2 hours) and the pit entry temperature range, to reduce the generation of peculiar smell substances by miscellaneous bacteria metabolism; Adopting the fermentation management mode of "double-layer sealing + daily tight barrel", the fermentation environment is ensured to be stable, and the loss of grains is controlled (≤3%), and the utilization rate of raw materials is improved.

[0011] Temperature and speed controlled distillation: Optimizing the upper distillation mode (layer-by-layer steam exploration, thin paving and uniform scattering) and distillation parameters (steam pressure, wine flow temperature / speed), combined with the "truncated tail, flower watching and wine picking" process, effectively removes harmful substances such as methanol and fusel oil in the wine; According to the acidity characteristics of mung bean lees, the "on-demand open steaming" mechanism is designed to avoid excessive acidity affecting the taste of the base wine.

[0012] Whole-process sanitary cleaning: Establish a "daily cleaning + deep disinfection" health management system, and clearly define the disinfection methods (70°C hot water flushing, ultraviolet disinfection, etc.) of tools, equipment, and sites to reduce the risk of bacterial contamination from the source.

[0013] Process control: Record the key parameters of the whole process and keep the base wine samples to achieve traceability of the production process and controllability of the quality, ensuring the standardization and lean production of handcrafted brewing.

[0014] Beneficial effects The present application has the following remarkable beneficial effects: Improved gelatinization uniformity: By separating and soaking the grains, and by gradient steaming, the gelatinization rate of the five types of grains reaches more than 95%, which is 10-15% higher than traditional mixed processing, solving the problem of "over-gelatinization in some areas and under-gelatinization in others"; Optimized fermentation coordination: Two-stage inoculation and low-temperature fermentation mode improve the saccharification rate by more than 20% during the fermentation process, the content of beneficial microbial metabolites (ethyl acetate, ethyl lactate, etc.) is more balanced, and the flavor coordination of the base wine is significantly improved; Enhanced quality stability: Standardized process parameters and whole-process control make the coefficient of variation of total ester content between base wine batches ≤8%, which is more than 12 percentage points lower than traditional methods, and the taste consistency is greatly improved; Reduced bacterial contamination rate: Whole-process sanitary cleaning and airing bed sterilization design make the bacterial contamination rate during the fermentation process ≤2%, which is more than 80% lower than traditional methods, and the pass rate of the base wine is improved to more than 98%; Improved raw material utilization rate: Precise grain soaking, steaming, and fermentation control improve the raw material yield (based on 52% vol base wine) by 3-5 percentage points, while the loss of grains is controlled within 3%, reducing production costs. DETAILED DESCRIPTION

[0015] The present invention will be further described in detail below with reference to two specific embodiments.

[0016] This invention provides a method for the handcrafted brewing of solid-state fermented Daqu-style light-aroma Wuliangye liquor, comprising the following steps: (1) Raw material inspection and pretreatment: Five kinds of grains are taken: red sorghum, Northeast sorghum, black buckwheat, Job's tears, and mung beans. After counting the quantity, sensory quality inspection is carried out to remove grains that are moldy, spoiled, have an off-odor, or contain serious ash residue impurities; (2) Precise soaking of grains: Five independent stills are cleaned, hot water is poured into the bottom pot of each still and heated to 45℃±2℃, and stirred evenly with a stainless steel spatula. The water temperature is confirmed to be uniform by measuring the temperature at multiple points; the five kinds of grains are poured into the corresponding stills respectively, and the soaking water temperature is set according to the grain variety: red sorghum 70℃, Northeast sorghum 75℃, black buckwheat 50℃, Job's tears 20℃, and mung beans 15℃; the soaking water level is adjusted according to the grain variety: red sorghum and Northeast sorghum are 50-80℃ higher than the grain surface. Centimeters, black buckwheat and Job's tears are 40-60 cm above the grain surface, and mung beans are 30-50 cm above the grain surface; scrape the grain surface, use a ladle and a strainer to remove foam and suspended matter, cover the pot and soak for 10-18 hours, during the soaking period ensure that the bottom pot valve is not leaking water and the steam valve is completely closed; after soaking, first remove floating impurities and foam, add soaking water while stirring continuously, discharge mud, sand and ash, use a strainer to check if there is grain leakage in the drainage, the soaking effect should reach the grain being thoroughly cooked and not undercooked; (3) Gradual steaming of grains: ① After the soaking water is drained, close the bottom pot valve, inject water into the bottom pot from the water pipe (the water level does not exceed 2-5 cm of the steamer grate), open the steam valve to heat; ② Initial steaming: loosen the grain with a shovel to ensure that the steam is even, avoid stepping on the steam and escaping the steam, after the steam is fully steamed, cover the pot and start timing, the initial steaming time is set according to the grain variety: red tassel sorghum 30 minutes, Northeast sorghum 30 minutes, black buckwheat 20 minutes 20 minutes for Job's tears, 20 minutes for mung beans; ③ Soaking in water: After the initial steaming, open the lid and quickly add water, controlling the steam volume to prevent boiling. Stir the grains to ensure even water absorption. The soaking time should be adjusted according to the season: 20-25 minutes in the cold season and 15-20 minutes in the hot season. The standard for judgment is that the grains are slightly hard and have been thoroughly soaked. During the soaking period, multiple samples should be taken to check the thoroughness of the grains. ④ Re-steaming: After the soaking, close the steam valve, open the bottom pot valve to drain the water and check for grain leakage. After draining, close the bottom pot valve and open the steam valve to heat. After the steam is fully released, close the lid and start timing. The re-steaming time is set according to the grain variety: 40 minutes for red sorghum, 40 minutes for Northeast sorghum, 30 minutes for black buckwheat, 30 minutes for Job's tears, and 35 minutes for mung beans. The time can fluctuate by ±5 minutes in cold and hot seasons, but should not be lower than the above lower limit. ⑤ Open steaming for disinfection: After the re-steaming, open the tray and steam for 5-10 minutes. Remove the steam for 1 minute, and at the same time, put tools such as rakes, shovels, snow rakes, dustpans, brooms, and box scrapers into the steamer for fumigation and disinfection. After steaming, close the steam valve, drain the water from the bottom pot, and quickly remove the grain from the steamer to cool and dissipate heat. The steamed grain should be lightly damp, thin-skinned, tender, and have absorbed the sweat. The opening size should be moderate and uniform, with an opening rate of ≥90% and a turning over rate of ≤5%.(4) Two-stage inoculation and cultivation: ① After the cooked grain is steamed, spread it evenly on the ventilated drying bed, turn on the fan and blow downwards for 10-20 minutes to sterilize the cooked grain with steam and blow away the moldy material residue under the drying bed; ② Switch to blowing upwards to cool down, so that the temperature of the cooked grain is uniform; the amount of koji is controlled at 5-10% (based on the total mass of the cooked grain), and koji is inoculated twice: in the cold season (room temperature ≤10℃), the first inoculation of red sorghum is at 35℃ and the second inoculation is at 25℃, the first inoculation of Northeast sorghum is at 35℃ and the second inoculation is at 25℃, the first inoculation of black buckwheat is at 30℃ and the second inoculation is at 20℃, the first inoculation of Job's tears is at 25℃ and the second inoculation is at 20℃, and the first inoculation of mung beans is at 28℃ and the second inoculation is at 18℃; when the room temperature is 10-20℃, all grains are inoculated at 30℃±2℃ for the first inoculation and 25℃±2℃ for the second inoculation; (5) Mixed low-temperature fermentation in the pit: ① After inoculation, the five grains are thoroughly mixed. The temperature of the cellar is controlled at 18-25℃ in the cold season and the temperature of the cellar is consistent with the room temperature in the hot season (error ≤2℃); ② Follow the principle of "low temperature cellar entry, quick filling and tight barrel, low temperature fermentation". The filling time is ≤2 hours. Tighten the barrel once a day. Use a double layer of sealing film + yellow mud to seal the cellar; ③ The fermentation cycle is 28-35 days. Before removing the cellar, scrape off the moldy fermented mash (rejection rate ≤3%). Remove the fermented mash after it is loose. After removing the cellar, wash the inner wall of the cellar, the mud puddle and the sealing film with 70-80℃ hot water. Dry it and set it aside for later use; (6) Temperature and speed control distillation: ① Before distillation, pour the first 500ml of the first distillation or the first still into the bottom pot, spread the still grate, and use the "lightly sprinkle and spread evenly, explore the steam layer by layer" method for loading the still. The thickness of each layer of material is 5-8 mm. ① Prevent steam from rising to a depth of 4-5 cm to avoid steam leakage and cross-contamination; ② When the steam rises evenly to 4-5 cm, cover the cloud plate and control the steam pressure to 0.02-0.05 MPa, implementing the principle of "cutting off the head and tail, observing the pattern and picking the liquor", and following the principle of "slow steam for distillation, large steam for tail-end distillation"; ③ Control the temperature of the distillate: ≤25℃ when the room temperature is <20℃, ≤30℃ when the room temperature is ≥20℃; the distillate flow rate is 2.5-3.5 jin / minute (not exceeding 4 jin / minute), and the ice bucket should be kept hot (≥60℃) during the distillation process, and cold water should not be used to replace it; ④ After distillation, test the acidity of the mung bean lees (if pH≤3.5, open distillation is required). If open distillation is required, drain the water from the bottom pot and distill for 10-15 minutes. (7) Full-process hygiene cleaning: Rinse all tools, equipment contact surfaces and production site with hot water above 70℃, disassemble and clean the ventilation drying bed and disinfect with ultraviolet light for 30 minutes, clean the production site daily and deeply disinfect it once a week; (8) Process control: Record key parameters (soaking water temperature / time, steaming time, inoculation temperature, cellar / fermentation temperature, wine flow temperature / speed) every day, retain a sample of the original wine for each batch (500ml / batch), and keep it for ≥6 months.

[0017] The optimal weight ratio of the five grain ingredients is as follows: 35% red sorghum, 25% Northeast sorghum, 15% black buckwheat, 15% Job's tears, and 10% mung beans.

[0018] Example 1 (Cold season production, room temperature 8°C) Raw material inspection and pretreatment: 120 kg of red sorghum, 120 kg of Northeast sorghum, 60 kg of black buckwheat, 60 kg of Job's tears, and 60 kg of mung beans were issued. Sensory inspection was conducted to remove 4.5 kg of moldy or odorous grains. The remaining raw materials were reserved for later use. Precise grain soaking: Clean five steamers, pour hot water into the bottom pot and heat to 45℃, stir well and measure the temperature at multiple points (temperature difference ≤1℃); put the five kinds of grains into the steamers separately, and set the soaking water temperature as follows: red sorghum 70℃, Northeast sorghum 75℃, black buckwheat 50℃, Job's tears 20℃, and mung beans 15℃, with water levels of 60 cm, 70 cm, 50 cm, 40 cm, and 40 cm respectively; after scraping the grain surface to remove impurities, cover the pot and soak for 16 hours; after soaking, drain the soaking water and stir to remove impurities, check with a strainer to ensure no grain leakage, and that all five kinds of grains are thoroughly cooked without any undercooked parts; Grain steaming in stages: After the soaking water is drained, pour water into the bottom pot (the water level should be 3 cm from the steamer grate) and turn on the steam valve to heat it. First steaming: Steam red sorghum and Northeast sorghum for 30 minutes, black buckwheat and Job's tears for 20 minutes, and mung beans for 25 minutes; Water soaking: During the cold season, soak the grains in water for 22 minutes, and sampling inspection shows that the grain penetration rate is 100%. Re-steaming: Steam red sorghum and Northeast sorghum for 40 minutes, black buckwheat and Job's tears for 30 minutes, and mung beans for 35 minutes; Open steaming: Open the steamer and steam for 8 minutes, then place the steamer with tools for fumigation and disinfection; remove the steamer and spread out to cool. After steaming, the grain opening rate is 92% and the grain turning rate is 3%, which meets the requirements. Two-stage inoculation culture: After the cooked grain is spread out, the fan blows air for 15 minutes to sterilize it, and then blows air to cool it down. Use 8% koji (based on the total mass of cooked grain) and inoculate according to the cold season parameters: Red tassel sorghum first inoculation at 35℃ and second inoculation at 25℃, Northeast sorghum first inoculation at 35℃ and second inoculation at 25℃, Black buckwheat first inoculation at 30℃ and second inoculation at 20℃, Job's tears first inoculation at 25℃ and second inoculation at 20℃, Mung beans first inoculation at 28℃ and second inoculation at 18℃. Mixed low-temperature fermentation in cellar: After mixing, the temperature of the mixture is controlled at 22℃, and the filling time is 1.5 hours. Double-layered sealed fermentation pits, with the pits tightened once a day, and a fermentation cycle of 32 days; Before removing the pit, scrape off 1.8 kg of moldy and spoiled material (1.5% loss rate). After removing the pit, rinse the pit with 75℃ hot water and let it dry. Temperature and rate controlled distillation: Pour the first 600ml of liquor and the last 42% vol of liquor into the bottom pot, and steam it layer by layer into the still (each layer is 6 cm thick). SAIC 5 cm rear cover cloud plate, steam pressure 0.03 MPa, liquor temperature 23℃, liquor flow rate 3 jin / minute; After distillation, the pH of the mung bean lees was measured to be 4.2. No need for open distillation. Rinse the still and drain the water from the bottom pot. Hygiene and cleaning: Rinse tools and equipment with 75℃ hot water, disassemble and clean the ventilated drying bed, disinfect with ultraviolet light for 30 minutes, and clean the production site; Process control: Record all key parameters and retain 500ml of raw wine sample.

[0019] The original liquor produced in this embodiment has an alcohol content of 52% vol, a total acid (calculated as acetic acid) of 0.52 g / L, and a total ester (calculated as ethyl acetate) of 2.9 g / L. It has a pure and refreshing aroma, a mellow and sweet taste, and no off-flavors, meeting the superior grade standard for light-aroma baijiu produced by solid-state fermentation.

[0020] Example 2 (Production during hot season, room temperature 28°C) Raw material inspection and pretreatment: 100kg of red sorghum, 100kg of Northeast sorghum, 50kg of black buckwheat, 50kg of Job's tears, and 50kg of mung beans were issued, and 3.1kg of unqualified grains were removed; Precise grain soaking: After cleaning the steamer, heat the bottom pot to 45°C, and put the five kinds of grains into the steamer separately. The soaking water temperature is the same as in Example 1, and the water levels are 50 cm, 60 cm, 40 cm, 35 cm and 30 cm respectively. After soaking for 12 hours, drain the soaking water to remove impurities and check for any grain leakage. Grain steaming in stages: The initial steaming and re-steaming times are the same as in Example 1, and the soaking time is 18 minutes (hot season). After steaming for 6 minutes, the grain opening rate was 91% and the grain turning rate was 4%, which met the requirements. Two-stage inoculation culture: Sterilize by 12 minutes of ventilation, and cool by forced air; use 6% of the starter culture, with the first inoculation at 30℃ and the second inoculation at 25℃. Mixed low-temperature fermentation in cellar: After mixing, the temperature inside the pit is 28℃ (consistent with room temperature), and the filling time is 1.8 hours. Double-sealed, with the container tightened once daily, fermentation cycle of 28 days; Before removing the pit, scrape off 1.2 kg of moldy and rotten material (2.1% loss rate). After removing the pit, rinse the pit with 70℃ hot water. Temperature and rate controlled distillation: 500ml of the first and last 50ml of the distillate (43% vol) are placed in the bottom pot and then layered on top of the still. The temperature of the liquor flowed was 29℃, and the flow rate was 3.2 jin / minute. After distillation, the pH of the mung bean lees was measured to be 3.4. After draining the water from the bottom pot, the mixture was steamed open for 12 minutes. After removing the lees from the steamer, the steamer was rinsed. Sanitation and cleaning: Same as in Example 1; Process control: Record parameters and retain samples of raw wine.

[0021] The original wine produced in this embodiment has an alcohol content of 52% vol, total acidity of 0.48 g / L, and total esters of 2.7 g / L. It has a harmonious flavor and a clean taste, meeting the superior grade standard.

Claims

1. A solid-state method of hand-craft fine brewing of Luzhou-flavor five-grain liquor with Daqu, characterized in that Comprising the following steps: (a) soaking grains process: red silk sorghum, northeast sorghum, black bitter buckwheat, Job's tears, green beans are treated according to the following parameters respectively: Red silk sorghum: water temperature 70℃, soaking for 12 hours; Northeast sorghum: water temperature 75℃, soaking for 14 hours; Black bitter buckwheat: water temperature 50℃, soaking for 10 hours; Job's tears: water temperature 20℃, soaking for 18 hours; Green beans: water temperature 15℃, soaking for 16 hours; (b) steaming grains process: 0.5% edible alkali is added before re-steaming of black bitter buckwheat; The re-steaming time of green beans is 35 minutes; (c) inoculation and bacteria cultivation process: the amount of koji for green beans is 8%, and the koji temperature is 28℃ / 18℃; (d) pit fermentation process: the pit temperature in cold season is 20℃, and the fermentation period is 60 days; (e) distillation process: the flow speed of liquor is 3.0-3.5 kg / min, and the flow temperature of liquor is ≤25℃ (room temperature ≤20℃) or ≤30℃ (room temperature >20℃).

2. A solid-state method of hand-craft fine brewing of Luzhou-flavor five-grain liquor with Daqu, characterized in that, Comprising the following steps: (1) Raw material inspection and pretreatment: Take red silk sorghum, northeast sorghum, black buckwheat, Job's tears, and green beans as raw materials. After counting the quantity, sensory quality inspection is conducted to remove moldy, rancid, odorous, and severely impure grains; (2) Precise grain separation and soaking: Clean five independent retort pots, pour hot water into the bottom pot of each retort pot and heat to 45℃±2℃, stir evenly with a stainless steel shovel, and confirm uniform water temperature through multi-point temperature measurement; Pour the five kinds of grains into the corresponding retort pots, and set the soaking water temperature according to the grain type: 70℃ for red silk sorghum, 75℃ for northeast sorghum, 50℃ for black buckwheat, 20℃ for Job's tears, and 15℃ for green beans; Adjust the water level according to the grain type: 50-80 cm above the grain surface for red silk sorghum and northeast sorghum, 40-60 cm above the grain surface for black buckwheat and Job's tears, and 30-50 cm above the grain surface for green beans; Flatten the grain surface, remove foam and suspended solids with a ladle and strainer, cover the pot lid and soak for 10-18 hours, ensure that the bottom pot valve has no water leakage and the steam valve is completely closed during soaking; After soaking, remove floating impurities and foam, continuously stir while draining the water, drain the sediment and impurities, check if there is any grain leakage in the drainage water, and the soaking effect should meet the requirements of thorough soaking, no undercooked grains; (3) Gradient steaming of separated grains: ① After draining the soaking water, close the bottom pot valve, pour water into the bottom pot from the steam pipe (water level should not exceed 2-5 cm above the retort grate), and open the steam valve to heat; ② Initial steaming: loosen the grains with a shovel to ensure uniform steam distribution, avoid steam stepping and running, cover the pot lid and count the time after successful large steam, and set the initial steaming time according to the grain type: 30 minutes for red silk sorghum, 30 minutes for northeast sorghum, 20 minutes for black buckwheat, 20 minutes for Job's tears, and 25 minutes for green beans; ③ Water soaking: after initial steaming, open the pot lid and quickly drain the water, control the steam size to prevent boiling, and stir the grains to ensure uniform water absorption; Adjust the water soaking time according to the season: 20-25 minutes in cold season and 15-20 minutes in hot season, the judgment standard is that the grains are slightly hard and the water is fully absorbed, and sample checking should be conducted during water soaking to ensure the thoroughness of the grains; ④ Re-steaming: after water soaking, close the steam valve, open the bottom pot valve to drain the water and check for grain leakage, close the bottom pot valve after draining the water, open the steam valve to heat, cover the pot lid and count the time after successful large steam, and set the re-steaming time according to the grain type: 40 minutes for red silk sorghum, 40 minutes for northeast sorghum, 30 minutes for black buckwheat, 30 minutes for Job's tears, and 35 minutes for green beans, the time can be adjusted by ±5 minutes in cold and hot seasons but should not be lower than the above lower limit; ⑤ Open steaming and disinfection: after re-steaming, open the cloud disc for 5-10 minutes to remove the sun water, and put the tools such as rakes, steel shovels, snow rakes, end picks, brooms, and box scrapers into the retort for fumigation and disinfection; After open steaming, close the steam valve, drain the water in the bottom pot, quickly remove the retort, and spread the grains to cool down; The steamed grains should meet the requirements of light weight, thin skin, softness, sweat collection, appropriate and uniform opening size, opening rate ≥90%, and flower rate ≤5%.(4) Two-stage inoculation and cultivation: ① After the cooked grain is steamed, spread it evenly on the ventilated drying bed, turn on the fan and blow downwards for 10-20 minutes to sterilize the cooked grain with steam and blow away the moldy material residue under the drying bed; ② Switch to blowing upwards to cool down, so that the temperature of the cooked grain is uniform; the amount of koji is controlled at 5-10% (based on the total mass of the cooked grain), and koji is inoculated twice: in the cold season (room temperature ≤10℃), the first inoculation of red sorghum is at 35℃ and the second inoculation is at 25℃, the first inoculation of Northeast sorghum is at 35℃ and the second inoculation is at 25℃, the first inoculation of black buckwheat is at 30℃ and the second inoculation is at 20℃, the first inoculation of Job's tears is at 25℃ and the second inoculation is at 20℃, and the first inoculation of mung beans is at 28℃ and the second inoculation is at 18℃; when the room temperature is 10-20℃, all grains are inoculated at 30℃±2℃ for the first inoculation and 25℃±2℃ for the second inoculation; (5) Mixed low-temperature fermentation in the pit: ① After inoculation, the five grains are thoroughly mixed. The temperature of the cellar is controlled at 18-25℃ in the cold season and the temperature of the cellar is consistent with the room temperature in the hot season (error ≤2℃); ② Follow the principle of "low temperature cellar entry, quick filling and tight barrel, low temperature fermentation". The filling time is ≤2 hours. Tighten the barrel once a day. Use a double layer of sealing film + yellow mud to seal the cellar; ③ The fermentation cycle is 28-35 days. Before removing the cellar, scrape off the moldy fermented mash (rejection rate ≤3%). Remove the fermented mash after it is loose. After removing the cellar, wash the inner wall of the cellar, the mud puddle and the sealing film with 70-80℃ hot water. Dry it and set it aside for later use; (6) Temperature and speed control distillation: ① Before distillation, pour the first 500ml of the first distillation or the first still into the bottom pot, spread the still grate, and use the "lightly sprinkle and spread evenly, explore the steam layer by layer" method for loading the still. The thickness of each layer of material is 5-8 mm. ① Prevent steam from rising to a depth of 4-5 cm to avoid steam leakage and cross-contamination; ② When the steam reaches a uniform depth of 4-5 cm, cover the cloud plate and control the steam pressure to 0.02-0.05 MPa, implementing the principle of "cutting off the head and tail, observing the pattern and picking the liquor", and following the principle of "slow steam for distillation, large steam for tail-end distillation"; ③ Control the temperature of the distillate: ≤25℃ when the room temperature is <20℃, ≤30℃ when the room temperature is ≥20℃; the distillation speed is 2.5-3.5 jin / minute (not exceeding 4 jin / minute), and the ice bucket should be kept hot (≥60℃) during the distillation process, and cold water should not be used to replace it; ④ After distillation, test the acidity of the mung bean lees (if pH≤3.5, open distillation is required). If open distillation is required, drain the water from the bottom pot and distill for 10-15 minutes. Minutes, after steaming, rinse the steamer and steamer grate and drain the bottom pot water; (7) Full process hygiene cleaning: use hot water above 70℃ to rinse all tools, equipment contact surfaces and production site, disassemble and clean the ventilation drying bed and disinfect it with ultraviolet light for 30 minutes, clean the production site daily and deeply disinfect it once a week. (8) Process control: record key parameters (soaking grain water temperature / time, steaming time, inoculation temperature, pit / fermentation temperature, liquor temperature / speed) every day, and store original liquor samples (500ml / batch) for ≥6 months.

3. The method of claim 2, wherein, In step (2), the soaking grain water temperature is allowed to fluctuate ±2℃, the soaking time is 15-18 hours in cold season and 10-13 hours in hot season.

4. The method of claim 3, wherein, In step (3), the grain core penetration degree in the water soaking stage is checked by the "random sampling + hand kneading observation" method, the sampling number is ≥5 grains / retort pot, and the core penetration rate needs to reach 100%.

5. The method of claim 4, wherein, In step (4), the Daqu is a solid-state fermentation Luzhou-flavor Daqu, with saccharifying power ≥1500U / g and liquefying power ≥800U / g.

6. The method of claim 5, wherein, In step (5), the pit is a pottery pit, the inner wall of the pit is smooth without cracks, and the pit is rinsed and disinfected with hot water above 70℃ before fermentation and dried.

7. The method of claim 6, wherein, In step (6), the head cut-off amount is 500-800ml per retort, and the tail cut-off amount is when the alcohol degree drops to 45%vol, and the head and tail are used for bottom pot ingredients for the next distillation.

8. The method of claim 7, wherein, In step (7), deep disinfection adopts the combination of 75% edible alcohol spraying and ultraviolet irradiation, and the disinfection time is ≥60 minutes.

9. The brewing process according to one of claims 1 to 8, characterized in that, The weight ratio of the five kinds of grain raw materials is: red silk sorghum 35%, northeast sorghum 25%, black bitter buckwheat 15%, Job's tears 15%, and green beans 10%.