Airing hall bacterium cultivation method and application thereof

Abstract

The invention belongs to the technical field of fermentation engineering, and relates to a method for cultivating bacteria in an airing room and application thereof. A method for cultivating bacteria in an airing hall comprises the following steps that S1, high-temperature Daqu waste grass and high-temperature large-area powder are matched according to the mass ratio of 5: 1 and laid on the ground of the airing hall, a waste grass ground layer is formed, and the laying thickness of the waste grass ground layer is 5-8 cm; s2, the surface of the waste grass ground layer is covered with a heat preservation layer, and the temperature of the waste grass ground layer is kept at 40-45 DEG C for no less than 7 days; s3, removing the thermal insulation layer, and laying the fermented grains with the temperature lower than 30 DEG C on the waste grass ground layer to form a microbial colonization layer with the thickness of 15-20 cm; and S4, the waste grass ground layer is removed, an inorganic salt solution with the mass fraction of 0.1-0.3% is sprayed and supplemented to the ground of the airing hall, and liquid supplementing is continuously conducted for 14-21 days. According to the method, the activity of ground microorganisms is rapidly activated by utilizing residual nutrients of waste grass and inherent flora, free flora in the environment is adsorbed, proliferation is promoted, straw resource utilization is achieved, and the cost of a bacterium culture cycle is reduced.

Description

Technical Field

[0001] This invention belongs to the field of fermentation engineering technology and relates to a method for cultivating bacteria in an open-air chamber and its application. Background Technology

[0002] Maotai-flavor baijiu is highly favored by consumers for its unique "maotai" aroma. The formation of its distinctive flavor largely depends on the aroma-generating function of Bacillus and other microorganisms during fermentation, especially in the crucial drying and stacking fermentation stage. However, in the initial stages of new brewing workshops or the start-up of new production batches, the microbial environment on the drying floor is often relatively weak. To cultivate and enrich the required microbial communities, especially functional Bacillus, traditional processes typically involve adding high-temperature Daqu (a type of starter culture) and spraying the tail liquor (the distilled spirits). A significant limitation of this traditional cultivation method is the long cycle of microbial acclimatization and microecological construction, usually requiring 2-3 months to reach the ideal microecological environment. This undoubtedly increases the time and economic costs of starting up new workshops and batch transitions.

[0003] It is worth noting that waste straw (i.e., used covering straw and other materials) is generated during the production of high-temperature Daqu (a type of Chinese liquor). This waste straw possesses unique potential value: on the one hand, it is rich in residual starch, protein, and other unconsumed nutrients; on the other hand, through the cultivation process of the Daqu, the waste straw naturally accumulates and contains a large number of heat-resistant Bacillus and other functional microorganisms. However, under traditional treatment methods, this resource, rich in valuable microbial strains and residual nutrients, is often simply discarded as waste, failing to be effectively utilized.

[0004] Therefore, in the current production of Maotai-flavor liquor, how to efficiently construct a micro-ecological environment rich in target functional bacteria (especially key Bacillus) in the drying hall to significantly shorten the cultivation cycle; at the same time, how to transform and utilize the waste straw resources generated during the high-temperature Daqu production process in a high-value manner to avoid the waste of valuable resources has become a key technical bottleneck and resource optimization issue that the industry urgently needs to solve.

[0005] To address the aforementioned background and industry pain points, this invention proposes an innovative brewing process for fermentation in a drying hall based on high-temperature Daqu (a type of starter culture) waste straw resources. The core of this process involves pulverizing the collected high-temperature Daqu waste straw and mixing it evenly with high-temperature Daqu powder in a specific ratio. This mixture is then spread on the drying hall floor, forming a specially designed "microbial carrier layer." This carrier layer fully utilizes the residual nutrients in the waste straw and its inherent thermotolerant microbial flora (mainly Bacillus), rapidly activating and enhancing the activity of dormant or sparse microorganisms on the drying hall floor. Simultaneously, this structure effectively adsorbs free microbial flora from the ambient air and provides a suitable microenvironment for the proliferation of all target microorganisms. This innovative process achieves the resource-based recycling of high-temperature Daqu waste straw from brewing production and significantly reduces the cycle costs required for traditional drying hall fermentation.

[0006] Furthermore, on the one hand, there are differences in understanding among those skilled in the art; on the other hand, the inventors studied a large number of documents and patents when making this invention, but due to space limitations, not all details and contents were listed in detail. However, this does not mean that the present invention does not possess the features of these prior art. On the contrary, the present invention already possesses all the features of the prior art, and the applicant reserves the right to add relevant prior art to the background art. Summary of the Invention

[0007] This invention belongs to the field of fermentation engineering technology and relates to a method for cultivating bacteria in an open-air chamber and its application.

[0008] To address the aforementioned technical problems, one objective of this invention is to provide a method for cultivating bacteria in a drying room, comprising the following steps: S1 high-temperature Daqu waste straw and high-temperature Daqu powder are mixed at a mass ratio of 5:1 and laid on the drying floor to form a waste straw floor layer with a thickness of 5~8 cm. The surface of the S2 waste straw ground layer is covered with an insulation layer, and the temperature of the waste straw ground layer is maintained at 40~45℃ for no less than 7 days. S3 removes the insulation layer and spreads the fermented mash with a temperature below 30°C on the waste straw ground layer to form a microbial colonization layer with a thickness of 15-20cm. S4 Remove the waste straw ground layer and spray the drying hall floor with an inorganic salt solution with a mass fraction of 0.1~0.3%, and continue to replenish the solution for 14~21 days.

[0009] According to a preferred embodiment, in S1, the thickness of the waste grass ground layer is 8 cm.

[0010] According to a preferred embodiment, in S2, the temperature of the waste grass ground layer is maintained at 45°C.

[0011] According to a preferred embodiment, in S3, the microbial colonization layer is turned over every 12 hours. Preferably, the waste grass ground layer is turned over every 12 hours.

[0012] According to a preferred embodiment, in S1, the length of the high-temperature Daqu waste straw used for the waste straw ground layer is 1~3 cm.

[0013] According to a preferred embodiment, the mash is the middle layer of mash in the fermentation pit corresponding to the fermentation node.

[0014] According to a preferred embodiment, in S4, the relative humidity of the drying floor is maintained at 85%.

[0015] According to a preferred embodiment, in S4, the temperature of the drying floor is maintained at 55°C.

[0016] The present invention also aims to provide the application of the above method in the maintenance of fermentation pits, the cultivation of microorganisms on the ground of new koji-making workshops, and the directional cultivation of microorganisms in the environment.

[0017] According to a preferred embodiment, the pit maintenance is to enhance and maintain the microorganisms of Saccharopolysporum, Bacillus spp., and Croppenstein.

[0018] The beneficial effects of this technical solution are: The experimental example showed a significant improvement in the number of strains and flavor concentration quotient, and outperformed the control example in all detection indicators. This demonstrates that the experimental process (air-drying cultivation) more effectively enriched the key microbial community and promoted the transformation of its metabolites through specific parameters (such as high temperature and humidity control, and strain inoculation strategy), thereby directly improving the fermentation quality of Daqu.

[0019] In baijiu production, this dual optimization means that the experimental process can improve the yield and flavor quality of daqu (fermentation starter culture) – a higher number of strains enhances fermentation stability (reducing the failure rate), and a higher flavor concentration improves the aroma of the liquor (such as the increase in pyrazines and esters, which brings a more complex "cellar aroma"). For example, the doubling of 2,3,5,6-tetramethylpyrazine is crucial for the aroma profile construction of high-end baijiu.

[0020] This invention provides a microbial cultivation process based on the use of waste straw from high-temperature Daqu production in the drying hall of a brewing workshop. The waste straw is crushed and mixed with high-temperature Daqu powder, and then spread on the ground of the drying hall to form a "microbial carrier layer". The residual nutrients and inherent microbial community of the waste straw are used to quickly activate the activity of ground microorganisms, adsorb free microorganisms in the environment and promote their proliferation, thereby realizing the resource utilization of rice straw and reducing the cost of the cultivation cycle. Attached Figure Description

[0021] Figure 1 This is a flowchart of the steps involved in the method of incubating bacteria in a drying room according to the present invention. Detailed Implementation

[0022] In the description of this invention, terminology is used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. In the description of this invention, "a plurality of" means two or more, unless otherwise explicitly defined.

[0023] Unless otherwise specified, the experimental methods used in the following examples are all conventional methods; the materials, reagents or instruments used, unless otherwise specified by the manufacturer, are all commercially available reagents and materials; the conditions not specified in the examples are all carried out according to conventional conditions or conditions recommended by the manufacturer. At the same time, the present invention does not limit the source of the raw materials used. Unless otherwise specified, the raw materials used in the present invention are all commercially available products in this technical field.

[0024] The fermentation pits described in this application are those used for the production of baijiu (Chinese liquor) within the Langjiu Distillery. It should be noted that the microbial population settings and usage differ significantly between the middle layer of the fermentation pit at the corresponding fermentation stage and the bottom layer of the pit of the same quantity; they belong to different types of fermentation mash.

[0025] Example 1 The method for cultivating bacteria in an open-air drying room involved in this embodiment is as follows: Figure 1 As shown, it includes steps S1 to S4.

[0026] S1 Waste Grass Ground Layer Preparation The waste straw from high-temperature Daqu (a type of Chinese liquor) is chopped into 3 cm lengths and mixed with high-temperature Daqu powder at a mass ratio of 5:1. The mixed materials are then evenly spread on the drying floor to a thickness of 8 cm.

[0027] S2 microbial community activation Cover the laid waste straw ground layer with an insulating film, and maintain the internal temperature of the waste straw ground layer at 40℃ through steam assistance or other means. Ventilate the waste straw ground layer for 10 minutes every day for 7 days to activate bacteria such as slow-growing Bacillus and Saccharopolysporum in the waste straw.

[0028] S3 mash contact acclimatization Spread the fermented mash (discarded grains) at a temperature below 30℃ evenly on the surface of the waste straw ground layer after step two treatment, with a mash thickness of 15 cm. Utilize the residual sugar in the mash and the nutrients in the waste straw to synergistically promote microbial growth; turn the mash over every 12 hours and stir the waste straw at the bottom to promote the colonization of aerobic and facultative aerobic bacteria (such as saccharopolysporum and Croppenstein), continuing for 7 days.

[0029] S4 Environmental Metabolic Enhancement Remove the waste straw ground layer after S3 treatment, and spray 0.3% (NH4)2SO4 (by mass) onto the drying floor to adjust the C / N ratio of the ground layer; control the humidity at 85% and the temperature at 55℃, and selectively enrich ester-producing bacteria and pyrazinogenic bacteria (Saccharopolysporum, Bacillus) for 14 days.

[0030] Comparative Example 1 Within the drying area, high-quality high-temperature Daqu powder is manually sprinkled three times a day for a period of six days. During the sprinkling, it is essential to ensure complete coverage without any blind spots, ultimately resulting in a uniform layer of finely powdered high-temperature Daqu powder covering the surface of the drying area.

[0031] Comparative Example 2 The operation steps are the same as in Example 1, except that the thickness of the prepared raw materials is adjusted to 4 cm in S1.

[0032] Comparative Example 3 The operation steps are the same as in Example 1, except that ventilation is not performed during the S2 microbial community activation stage.

[0033] Comparative Example 4 The operation steps are the same as in Example 1, except that the mash added in the S3 mash contact acclimatization stage is replaced with an equal amount of mash from the bottom of the fermentation pit.

[0034] Comparative Example 5 The operation steps are the same as in Example 1, except that the surface temperature is not controlled during the S4 environmental metabolism enhancement stage.

[0035] The experimental results of the comparative examples and embodiments are shown in Tables 1 and 2 below.

[0036] Table 1 shows the number of microorganisms (CFU / g) in the fermented mash. Table 2 shows the content of flavor compounds in the fermented mash.

[0037] Table 1

[0038] As shown in Table 1, the open-air fermentation method of the present invention is significantly superior to the traditional fermentation method (Comparative Example 1), with an increase in the number of Bacillus, Polysporus, and Croppenstein species. Meanwhile, compared to the control groups with adjusted parameters (Comparative Examples 2 to 5), the fermentation effect was still inferior to the experimental example of the present invention. Using the open-air fermentation method of the present invention not only improves the abundance of microorganisms in the environment and on the ground, but also further enhances the microbial content in the fermented mash, thus creating a more favorable micro-ecological environment for the subsequent composting and fermentation process.

[0039] Table 1 shows that *Saccharopolysporum* produces flavor precursors, *Bacillus spp.* enhances fermentation stability, and *Croppenstein* is associated with heat resistance and metabolites. The experimental data indicate that the process of this invention (i.e., the experimental examples) significantly exceeded the comparative examples (Comparative Examples 1-5) in the number of all strains, reflecting a more efficient ability to enrich strains.

[0040] The experimental examples showed the highest values ​​across all strain indicators, demonstrating that the process of this invention (the open-air culture method) significantly improved the biomass of key strains by optimizing temperature, humidity, or nutrient ratios. This optimization of the strain community is one of the core aspects of the "dual optimization": on the one hand, it enhances the stability of the microbial community (e.g., the increase in slow-growing Bacillus prevents fermentation failure); on the other hand, it provides more metabolic sources for the synthesis of flavor compounds (e.g., the increase in Saccharopolysporum and Croppenstein directly supports ester formation).

[0041] Table 2

[0042] Table 2 shows that 2,3,5,6-tetramethylpyrazine (providing pyrazine aroma), ethyl oleate, ethyl linoleate, ethyl palmitate, and ethyl laurate (all esters contributing to a smooth mouthfeel) are present. The experimental example showed significantly higher scores than the comparative example in all flavor indicators, with a greater improvement. This indicates that the process of this invention achieves a significant enhancement of flavor by optimizing strain metabolism. After the application of this invention, the composition of the drying hall microorganisms was optimized, directly promoting a significant increase in the content of key flavor and health components—pyrazine compounds—in Maotai-flavor liquor. Simultaneously, the content of flavor substances that enhance the overall richness of the liquor, such as higher fatty esters, was also increased. This fully demonstrates the significant advantages of this invention in improving the flavor and quality of Maotai-flavor liquor.

[0043] The enzymatic activity of *Bacillus spp.* and *Croprunella* can catalyze esterification reactions to produce esters such as ethyl oleate; the enrichment of *Saccharopolysporum* may directly promote pyrazine synthesis. The experimental process, through optimization of the drying-in culture (such as adjusting ventilation or turning timing), amplified the metabolic efficiency of these strains, thereby achieving a dual optimization of flavor—not only higher concentrations but also a richer flavor profile (improved ester balance).

[0044] Before each batch of production begins, the present invention utilizes the waste straw and lees generated during the koji-making process to carry out a special microbial cultivation treatment on the drying hall. This method can effectively and specifically enrich the environmental microorganisms that are beneficial to fermentation, thereby ensuring the consistency and stability of the microbial environment at the beginning of each batch of fermentation, laying a good foundation for subsequent stable fermentation.

[0045] It should be noted that the specific embodiments described above are exemplary, and those skilled in the art can devise various solutions inspired by the disclosure of this invention. These solutions all fall within the scope of this invention and its protection. Those skilled in the art should understand that this specification and its accompanying drawings are illustrative and not intended to limit the scope of the claims. The scope of protection of this invention is defined by the claims and their equivalents.

Claims

1. A method for cultivating bacteria in a drying room, characterized in that, Includes the following steps: S1 high-temperature Daqu waste straw and high-temperature Daqu powder are mixed at a mass ratio of 5:1 and laid on the drying floor to form a waste straw floor layer with a thickness of 5~8 cm. The surface of the S2 waste straw ground layer is covered with an insulation layer, and the temperature of the waste straw ground layer is maintained at 40~45℃ for no less than 7 days. S3 removes the insulation layer and spreads the fermented mash with a temperature below 30°C on the waste straw ground layer to form a microbial colonization layer with a thickness of 15-20 cm; S4 Remove the waste straw ground layer and spray the drying hall floor with an inorganic salt solution with a mass fraction of 0.1~0.3%, and continue to replenish the solution for 14~21 days.

2. The method for cultivating bacteria in a drying room according to claim 1, characterized in that, In S1, the thickness of the waste grass ground layer is 8 cm.

3. The method for cultivating bacteria in a drying room according to claim 1, characterized in that, In S2, the temperature of the waste grass ground layer is maintained at 45°C.

4. The method for cultivating bacteria in a drying room according to claim 1, characterized in that, In S1, the length of the waste straw used for the high-temperature Daqu (a type of Chinese liquor) ground layer is 1~3 cm.

5. The method for cultivating bacteria in a drying room according to claim 1, characterized in that, In S3, the microbial colonization layer is turned over every 12 hours. Preferably, the waste grass ground layer is turned over every 12 hours.

6. The method for cultivating bacteria in a drying room according to claim 1, characterized in that, The fermented mash is the middle layer of the fermentation pit corresponding to the fermentation stage.

7. The method for cultivating bacteria in a drying room according to claim 1, characterized in that, In S4, the relative humidity of the drying floor is maintained at 85%.

8. The method for cultivating bacteria in a drying room according to claim 1, characterized in that, In S4, the temperature of the drying floor is maintained at 55℃.

9. The application of the method of cultivating bacteria in a drying hall in the maintenance of cellars, characterized in that, The method for cultivating bacteria in the drying room is the same as the method for cultivating bacteria in the drying room as described in claims 1 to 9.

10. The use according to claim 9, characterized in that, The maintenance of the cellar aims to enhance and maintain the microorganisms of the genera *Saccharomyces*, *Bacillus*, and *Croppensteine*.

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