Brewing process capable of boiling grains at constant high temperature and improving grain steaming efficiency

Abstract

The invention discloses a brewing process for improving the grain steaming efficiency by boiling grains at constant high temperature, and belongs to the technical field of white spirit brewing. The process comprises the steps of sorghum cleaning, constant-temperature grain cooking, spreading for cooling, adding yeast, fermenting in a barrel and distilling, and the core is that constant-temperature hot water of 60 + / -1 DEG C is adopted, three-stage cooking is matched with two-time deep turning under the micro-pressure environment of 0.02-0.05 MPa according to the water-grain ratio of (2.3-2.7): 1, the core penetration rate of cooked grains is larger than or equal to 95%, and the pretreatment time is shortened to 30 minutes; by combining three-stage temperature-controlled fermentation, acetaldehyde is reduced to 0.48 g / L, fusel oil is reduced to 1.12 g / L, the flavor and efficiency of the raw wine are improved, and the dual effects of energy conservation and quality improvement are achieved.

Description

Technical Field

[0001] This invention relates to the field of baijiu brewing technology, and specifically proposes a brewing process for daqu-style light-aroma baijiu, particularly involving a brewing process that optimizes the raw material pretreatment process by cooking grains at constant high temperatures to improve the efficiency of grain steaming and the quality of the original liquor. Background Technology

[0002] Daqu-style light aroma baijiu is an important category of traditional Chinese distilled spirits. Its brewing process uses glutinous sorghum as the main raw material and relies on the traditional "soaking-steaming" pretreatment method to gelatinize the raw materials, laying the foundation for subsequent fermentation and the generation of flavor substances.

[0003] In traditional processes, raw material pretreatment typically employs a combination of prolonged soaking and prolonged steaming: the soaking stage requires sorghum to be soaked in room temperature water for 18-20 hours to allow the raw material to fully absorb water; the steaming stage requires continuous high-temperature steaming for 80-85 minutes to ensure the cooked grain reaches a "thoroughly gelatinized" state (i.e., the starch granules are completely gelatinized). However, this process has the following significant drawbacks: Inefficient and costly: Soaking grain for a long time not only takes up a lot of production time, increases energy consumption and labor costs, but also consumes a lot of water resources and generates high-concentration soaking wastewater, increasing the pressure on environmental protection. High risk of raw material contamination: In the humid environment of the south, soaking grains for a long time can easily lead to mold growth or excessive microbial growth in sorghum, producing off-flavor substances that directly affect the purity of the raw liquor. Loss of flavor compounds: Prolonged high-temperature steaming will cause the unique grain aroma components in sorghum, such as pyrazines and aldehydes, to evaporate with the steam, resulting in a thin aroma in the liquor. High levels of defective components: Uneven soaking of grains or overcooking can lead to an imbalance in microbial metabolism during fermentation, causing the accumulation of defective components such as acetaldehyde and fusel oils in the original wine, which affects the smoothness and safety of the wine's taste.

[0004] Therefore, in response to the aforementioned pain points of traditional processes, there is an urgent need to develop a highly efficient, energy-saving, and stable pretreatment process that can shorten processing time, increase the permeability of cooked grains, reduce the content of defective components, and ultimately achieve a dual improvement in the quality of raw liquor and production efficiency. Summary of the Invention

[0005] In view of this, in order to solve the problems of low raw material pretreatment efficiency and the impact on the quality of raw liquor in the traditional Daqu light aroma baijiu brewing process, this invention provides a brewing process that improves the efficiency of steaming grain by constant high temperature grain cooking. By optimizing the grain cooking parameters and fermentation control strategy, the comprehensive effect of "improving efficiency, reducing impurities and enhancing aroma" is achieved.

[0006] This invention aims to solve the core problems in traditional processes, such as "low efficiency and easy mold growth due to prolonged soaking of grains", "loss of grain aroma due to prolonged steaming", and "high content of defective components", and provides a brewing process that can shorten pretreatment time, improve the permeability of cooked grains, and improve the flavor and safety of the original wine.

[0007] The technical solution of this invention is implemented as follows: This invention provides a constant high temperature grain cooking process to improve the efficiency of grain steaming and brewing, including the following steps: Sorghum cleaning: Clean the sorghum raw materials by adding room temperature water to submerge the grains by 3-5cm, stirring for 2.5-3.5 minutes, then draining the water to remove impurities and dust; Constant-temperature cooking: Pour 59-61℃ constant-temperature hot water into the still at a water-to-grain mass ratio of (2.3-2.7):1, add the washed sorghum raw materials, cover and maintain a micro-pressure environment of 0.02-0.05MPa, and perform the following steps in sequence: continuous cooking for 19-21 minutes, thorough stirring, continued cooking for 4.5-5.5 minutes, stopping steam and letting stand for 4.5-5.5 minutes, stirring a second time to break up clumps, and re-steaming for 4.5-5.5 minutes, so that the core penetration rate of the cooked grain is ≥95% and the moisture content is controlled at 50-53%; Cooling and adding koji: Spread the cooked grain obtained from constant temperature cooking evenly on a ventilated cooling bed and cool it to 18-21℃. Add 9.5-10.5% of the dry matter mass of the cooked grain with fragrant koji. Achieve micro-oxygen homogenization of the koji and grain by mechanical turning and mixing. After mixing, let it stand for 25-35 minutes for micro-oxygen activation. Fermentation in barrels: The mixed grain mash is placed into a fermentation container, sealed to form an anaerobic environment, and fermented for 30-35 days; the fermentation stage adopts a three-stage temperature control strategy of "slow at the beginning, strong in the middle, and slow at the end": in the early stage, the temperature is maintained at 18-20℃ for 4.5-5.5 days, in the middle stage, the temperature is maintained at 21-23℃ for 19-21 days, and in the later stage, the temperature is gradually reduced to 18℃ at a rate of 0.4-0.6℃ / day; Distillation: After fermentation, 4-6% rice husks are mixed into the mash to improve aeration. The mash is then fed into the still using a process of "slow steam loading, medium steam distillation, and high steam finishing" to obtain the raw brewed liquor. Optionally, the distilled liquor can be aged in vats.

[0008] In some implementations, thorough agitation means that the top 30% depth of the grain layer has an agitation rate of ≥95%.

[0009] In some implementations, breaking up agglomerates means that the proportion of agglomerate diameter > 2 cm is ≤ 2%.

[0010] In some implementations, an anaerobic environment is defined as an oxygen content of ≤0.5%.

[0011] In the process of this invention, the "turning rate" (turning rate of the grain layer at a depth of 30% from the surface) is calculated as follows: Defining the turning area: Based on the total height of the sorghum material in the still, the monitoring area is the material layer with a depth of 30% from the surface (for example, if the total height of the material is 100cm, the monitoring area is the material layer with a depth of 0-30cm from the surface).

[0012] Marking and statistics: Before turning, randomly select 3-5 sampling points in the monitoring area, and mark 100 sorghum grains at each point (this can be achieved by dyeing or physical marking); after the turning operation is completed, count the number of marked sorghum grains that have been turned from their original position (top 30% area) to the deeper layer (below 30% depth), and the number of unmarked sorghum grains from the deeper layer that have been turned to the top 30% area. The sum of the two is the "effective number of turned grains".

[0013] Calculation method: Flip rate = (Number of effectively flipped particles ÷ Total number of marked particles) × 100% For example, if 500 grains of sorghum are marked and 475 grains are turned over, the turning rate is 475 / 500×100%=95%, which meets the requirement of "turning rate of grain layer at a depth of 30% above the surface ≥95%".

[0014] This calculation method aims to quantify the mixing effect of the turning operation on the material layer, ensuring that the surface and deep layers of material are fully replaced, which is a key parameter to ensure the uniformity of grain cooking at constant temperature.

[0015] The present invention has the following advantages over the prior art: Significantly improve production efficiency and reduce costs By adopting a constant high temperature and low pressure grain cooking process, combined with three-stage steaming and precise turning, the pretreatment time of raw materials is shortened from 18-20 hours in the traditional process to about 30 minutes, which increases efficiency by about 36 times. At the same time, it reduces water consumption and wastewater discharge in the grain soaking process, reduces energy consumption and environmental treatment costs, and is in line with the trend of green brewing.

[0016] Improve the stability of cooked grain quality By precisely controlling the water-to-grain ratio, cooking time, and turning intensity, the core penetration rate of the cooked grain is kept stable at over 95%, and the moisture content is controlled at 50-53%. This avoids the problems of "partial incomplete core penetration" or "over-gelatinization" in traditional processes, providing a uniform and stable substrate for subsequent fermentation and improving the stability of starch conversion rate and alcohol yield.

[0017] Significantly reduces defective components and improves the safety of raw spirits Constant-temperature cooking of grains reduces the risk of mold growth in raw materials. Combined with three-stage temperature-controlled fermentation, it inhibits the metabolism of miscellaneous bacteria and balances yeast activity, reducing the acetaldehyde content in the original wine to about 0.48g / L and the fusel oil content to below 1.12g / L. This reduces the "spicy" taste and the risk of "headache" in the wine, and improves drinking safety.

[0018] Enrich and optimize the flavor of the wine Short-time steaming reduces the thermal volatilization of grain aroma substances. Combined with micro-oxygen homogenization and gradient cooling during the esterification stage, it promotes the synthesis of flavor substances such as esters, making the original wine's light aroma style purer, its taste smoother and sweeter, and its flavor layers more harmonious, thus solving the problem of the single flavor of wine made by traditional processes. Attached Figure Description

[0019] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0020] Figure 1 This is a process flow diagram of the present invention. Detailed Implementation

[0021] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0022] It should be noted that when a component is referred to as being "fixed to" or "set on" another component, it can be directly on or indirectly on that other component. When a component is referred to as being "connected to" another component, it can be directly connected to or indirectly connected to that other component.

[0023] It should be understood that the terms "length", "width", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this application.

[0024] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this application, "multiple" means two or more, unless otherwise explicitly specified.

[0025] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which the embodiments of this invention pertain. If any definition stated in this section is contrary to or otherwise inconsistent with a definition stated in a patent, patent application, published patent application, or other publication incorporated herein by reference, the definitions listed here shall prevail over those incorporated herein by reference.

[0026] Unless otherwise specified, the methods used in the following embodiments are conventional methods. Unless otherwise specified, the materials, reagents, and instruments used are conventional materials, reagents, and instruments in the art, and can be obtained commercially by those skilled in the art.

[0027] When a quantity, concentration, or other value or parameter is expressed as a range, a preferred range, or a range defined by a series of upper and lower preferred values, this should be understood as specifically disclosing all ranges formed by any pair of any upper or preferred value with any lower or preferred value, regardless of whether the range is disclosed individually. For example, when the range “1 to 5” is disclosed, the described range should be interpreted as including ranges “1 to 4”, “1 to 3”, “1 to 2”, “1 to 2 and 4 to 5”, “1 to 3 and 5”, etc. When numerical ranges are described herein, unless otherwise stated, the range is intended to include its endpoints and all integers and fractions within that range. In this specification and claims, range definitions may be combined and / or interchanged, unless otherwise stated, these ranges include all subranges contained therein.

[0028] Example 1 The impact of different grain steaming processes on the quality of cooked grain and raw liquor Take 100 kg of glutinous sorghum. After crushing, more than 90% of the grains should have a diameter of 1.5–3.5 mm, while less than 5% should have clumps larger than 2 cm in diameter. Divide the sorghum into four equal portions of 25 kg each, and perform the following four steaming treatments on each portion.

[0029] The first group used traditional methods: soaking in room temperature water for 18 hours, with the water level one finger above the grain surface; then steaming at normal pressure for 80 minutes. When the grain came out of the steamer, the moisture content was 49.69%, the grains felt sticky to the touch, the breakage rate was high, and the core penetration was insufficient. The sensory evaluation was "partially under-penetrated".

[0030] The second method involved steaming the sorghum without simmering: 60℃ hot water was added directly to the sorghum, with a grain-to-water ratio of 1:2.5, and the sorghum was steamed continuously at normal pressure for 30 minutes without being turned over. The resulting cooked sorghum had a moisture content of 45.92%, with loose but dry grains, a low breakage rate, and a significantly lower core penetration rate compared to the traditional method.

[0031] The third group used a method of steaming broken grains: the sorghum was not soaked before being directly mixed with room temperature water at a ratio of 1:2.5 and steamed at normal pressure for 30 minutes. When the grains came out of the steamer, the moisture content was 46.35%, but the grains clumped together, forming a large number of clumps with a diameter of more than 2 cm, and the core was not evenly distributed.

[0032] The fourth group used the constant-temperature cooking method of this invention: first, 60℃ hot water was poured into the still, with a water-to-grain mass ratio of 2.5:1, and the liquid level was one finger's width above the grain level; after covering, a slight pressure of 0.02–0.05 MPa was maintained, and the process was carried out in sequence: 20 minutes of steaming, turning, 5 minutes of continued steaming, 5 minutes of resting, turning again, and 5 minutes of re-steaming. When the grain was removed from the still, the moisture content was 51.65%, the grains were loose and free of clumps, and it was visually observed that the grains were completely cooked through.

[0033] The four comparisons show that although traditional long-term soaking can allow some grains to penetrate the core, it takes 18 hours; while methods such as not steaming the grain or breaking the grain shorten the time, they result in insufficient penetration; the present invention can obtain cooked grain with higher moisture content, looser texture and complete penetration in just 30 minutes.

[0034] The specific results are shown in the table below:

[0035] Example 2 The Influence of Different Distillation Methods on the Yield and Quality of the Original Wine Based on the four groups of cooked grains mentioned above, the grains were uniformly cooled, fermented, and distilled to investigate the impact of the distillation method on the final quality of the liquor. The fermentation period was 30 days, and the distillation process employed a slow-steam loading, medium-steam distillation, and high-steam finishing process.

[0036] The traditional process yielded an average alcohol yield of 46.93% after two rounds of fermentation. Gas chromatography analysis revealed that the original wine contained 0.78 g / L acetaldehyde, 0.18 g / L methanol, 0.29 g / L n-propanol, 2.45 g / L ethyl acetate, and 1.27 g / L fusel oil. The tasting panel rated it as having a light aroma, a sweet and mellow taste with a slight spiciness, and a clean finish, with an overall score of 91.5.

[0037] The alcohol yield of the non-stewed grain group plummeted to 34.85%; acetaldehyde rose to 1.29 g / L, ethyl acetate reached 4.16 g / L, and fusel oil was 1.15 g / L; the alcohol body was characterized by prominent ester aroma and a slight fruity aroma, but it was also very pungent, scoring 91.2.

[0038] The alcohol yield of the broken grain steaming group rebounded to 47.36%; acetaldehyde 0.73 g / L, ethyl acetate 2.98 g / L, fusel oil 1.10 g / L; the taste is light and fragrant with a slight fruity aroma, and sweet on the palate, scoring 91.9.

[0039] The constant-temperature grain cooking group of this invention has an alcohol yield of 46.33%, which is basically the same as the original process; key chromatographic indicators show that acetaldehyde is reduced to 0.48 g / L, methanol to 0.14 g / L, n-propanol to 0.33 g / L, ethyl acetate to 2.42 g / L, and fusel oil to 1.12 g / L; the taste test results show that it has a pure and fragrant aroma, a smooth and sweet taste, and a clean aftertaste, with an overall score of 91.5.

[0040] The results show that although the traditional process yields a slightly higher alcohol content, it also results in a higher concentration of defective components. This invention reduces acetaldehyde by 38% and fusel oil by 12% without lowering the alcohol content, resulting in a purer liquor. This fully demonstrates the superiority of the constant high temperature and low pressure grain cooking process.

[0041] The results are shown in the table below:

[0042] Example 3 Overall Energy Consumption and Sensory Comparison The traditional process involves soaking the grain at room temperature for 18 hours and then steaming it at normal pressure for 80 minutes. The steam consumption is 850 kg per ton of grain, and the total energy consumption is equivalent to 110.4 kg of standard coal.

[0043] This invention consumes only 320 kg of steam per ton of grain and 41.6 kg of standard coal equivalent in energy, a reduction of 62.3%. Pretreatment time has been drastically reduced from 19 hours and 20 minutes to 30 minutes. The acetaldehyde content in the new wine is 0.48 g / L, and the fusel oil content is 1.12 g / L, significantly lower than the traditional group's 0.78 g / L and 1.27 g / L, respectively. The main aromatic ethyl acetate content remains at 2.42 g / L, essentially the same as the traditional 2.45 g / L. A blind sensory evaluation panel of 10 people gave it an average score of 91.5, on par with the traditional method, but the taste description was changed from "fragrant and slightly spicy" to "fragrant, mellow, and sweet with a clean finish."

[0044] Example 4 The necessity of tumbling intensity The process of 60℃, 0.03 MPa, and 20+5+5 minutes was fixed, and the three levels of tumbling intensity were compared only.

[0045] The first stage has an 80% turnover rate after the first turn, and 8% still clumps after the second turn; the core penetration rate is 86%, the wine yield is 43.2%, and the fusel oil content is 1.35 grams per liter.

[0046] The second grade has a 95% overturn rate, a 2% clumping rate, a 95% core penetration rate, a 46.1% alcohol yield, and 1.12 grams of fusel oil per liter.

[0047] The third grade has a 98% overturning rate, a 1% clumping rate, a 97% core penetration rate, a 46.4% alcohol yield, and 1.10 grams of fusel oil per liter.

[0048] Data shows that if the "first-time flipping rate ≥ 95% and clumping rate ≤ 2%" as described in claim 4 are not met, the core penetration rate and wine yield will decrease significantly, and the defective components will increase. Therefore, this limitation is an essential technical feature.

[0049] 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, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A brewing process for improving the efficiency of grain steaming by constant high-temperature cooking, characterized in that, Includes the following steps: Sorghum washing: Wash the sorghum raw materials, add room temperature water to submerge the grains by 3-5cm, stir for 2.5-3.5 minutes, then drain the water; Constant temperature cooking: Pour 59-61℃ constant temperature hot water into the still at a water-to-grain mass ratio of (2.3-2.7):1, add the washed sorghum raw materials, cover and maintain a micro-pressure environment of 0.02-0.05MPa, and perform the following steps in sequence: continuous cooking for 19-21 minutes, thorough stirring, continued cooking for 4.5-5.5 minutes, stopping steam and letting stand for 4.5-5.5 minutes, turning a second time to break up clumps, and re-steaming for 4.5-5.5 minutes. Cooling and adding koji: Spread the cooked grain obtained from constant temperature cooking evenly on a ventilated cooling bed and cool it to 18-21℃. Add 9.5-10.5% of the dry matter mass of the cooked grain with fragrant koji. Achieve micro-oxygen homogenization of the koji grain by mechanical turning. Fermentation in barrels: The mixed grain mash is placed into a fermentation container, sealed to form an anaerobic environment, and fermented for 30-35 days. Three-stage temperature control is used during the fermentation stage. Distillation: After fermentation, 4-6 wt% rice husks are mixed into the mash to improve its permeability. The mash is then fed into the still using a slow-steam loading, medium-steam distillation, and high-steam tail-end process to obtain the brewed base liquor.

2. The brewing process as described in claim 1, characterized in that, The hot water temperature during the constant temperature grain cooking stage is 60℃.

3. The brewing process as described in claim 1, characterized in that, The pressure of the micro-pressure environment is controlled within the range of 0.03-0.04 MPa. The initial cooking time is 20 min, the subsequent cooking time is 5 min, the settling time is 5 min, and the re-steaming time is 5 min.

4. The brewing process as described in claim 1, characterized in that, During the turning operation, the first turning should be performed immediately after steaming for 19-21 minutes, with a turning rate of ≥95% for the top 30% depth of grain layer; the second turning should be completed within 2 minutes after standing for 4.5-5.5 minutes, with a clumping rate of ≥98% and a clumping diameter of >2cm accounting for ≤2%.

5. The brewing process as described in claim 1, characterized in that, The moisture content of the cooked sorghum raw material prepared by the constant high temperature cooking process is controlled at 50-53%, and the core penetration rate is ≥95%.

6. The brewing process as described in claim 1, characterized in that, In the cooling and adding koji step, the amount of koji added is 10% of the dry matter mass of the cooked grain, and the added koji powder is light-flavored koji. After mixing evenly, it is left to stand for 25-35 minutes for micro-oxygen activation.

7. The brewing process as described in claim 1, characterized in that, The oxygen content during the fermentation stage is controlled at ≤0.5%, and the fermentation container is sealed to maintain an anaerobic environment.

8. The brewing process as described in claim 1, characterized in that, The specific parameters of the three-stage temperature control strategy are as follows: in the early stage, the temperature is maintained at 18-20℃ for 4.5-5.5 days; in the middle stage, the temperature is maintained at 21-23℃ for 19-21 days; and in the later stage, the temperature is gradually reduced to 18℃ at a rate of 0.4-0.6℃ / day.

9. The brewing process as described in claim 1, characterized in that, In the constant high temperature grain cooking process, the proportion of crushed sorghum raw materials with a diameter of 1.5-3.5mm is not less than 90%, of which the proportion of lumps does not exceed 5%.

10. The brewing process as described in claim 1, characterized in that, In the initial fermentation stage, the yeast count in the mash is controlled at (1.0-3.0) × 10⁻⁶. 7 CFU / g.

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