A solid-state fermentation process of radix astragali

Abstract

This invention discloses a fully solid-state fermentation process for Astragalus membranaceus vinegar, specifically relating to the field of solid-state vinegar brewing technology. The process uses sorghum, rice husks, rice bran, wheat bran, Astragalus membranaceus, and Daqu (a type of starter culture) as raw materials, without adding any exogenous enzymes or chemical products. The process includes the following steps: S1. Astragalus membranaceus slices are diagonally sliced ​​and drained to a moisture content of 18%-22%; S2. Sorghum is steamed at normal pressure, with Astragalus membranaceus slices added after 20-25 minutes of steaming, and steaming continues for a total time of 40-60 minutes; S3. Sorghum undergoes variable-temperature alcoholic fermentation with rice bran, first-grain rice husks, and a portion of Daqu, without Astragalus membranaceus slices participating in this stage; S4. The mash is mixed with the remaining Daqu, wheat bran, second-grain rice husks, and softened Astragalus membranaceus slices under moist heat, and the moisture content is adjusted to 60%-65% before acetic acid fermentation, with the main fermentation temperature at 39℃-41℃; S5. The mash is aged in a sealed container with intermittent aeration; S6. Vinegar is obtained by gradient temperature leaching. This invention achieves simultaneous fermentation and self-degradation of Astragalus membranaceus fiber and in-situ conversion of its functional components through process timing control and physical parameter optimization.

Description

Technical Field

[0001] This invention relates to the field of solid-state vinegar brewing technology, specifically to a fully solid-state vinegar fermentation process that uses authentic medicinal herb Astragalus membranaceus as a special auxiliary material and does not add any exogenous enzyme preparations or chemical products. Background Technology

[0002] Tai Astragalus, also known as "Taiqi," specifically refers to the authentic Astragalus medicinal material produced in the Wutai Mountain area of ​​Xinzhou City, Shanxi Province. This product grows on sunny mountain slopes at altitudes of 1500-3000 meters. It has robust roots, is rich in starch, and contains abundant active ingredients, including at least 0.04% astragaloside A and at least 17% water-soluble extract. It has the effects of tonifying Qi, strengthening the exterior, and enhancing immunity.

[0003] There are existing technologies exploring the integration of Astragalus membranaceus, a medicinal and edible herb, into vinegar brewing. To address the issues of high lignification and difficulty in releasing active ingredients from Astragalus membranaceus, the following technical approaches are primarily employed: One approach is the pretreatment route using added enzymes. For example, patent CN120442352A discloses a fully solid-state fermentation process for astragalus vinegar. This process involves weak alkaline enzymatic hydrolysis pretreatment (using cellulase and pectinase), layered cooking, and humidity gradient control to chemically and physically degrade the astragalus cell wall, releasing polysaccharides and carbon sources. While this method addresses the release of astragalus components to some extent, it requires the additional preparation of a slow-release enzyme solution, introduces exogenous biological agents, and increases the process complexity.

[0004] Secondly, there's the issue of the astragalus extract addition route. Some existing technologies involve first extracting astragalus with water or alcohol, and then adding the extract to the vinegar mash. This method essentially involves "addition and blending" rather than "fermentation and transformation." The astragalus components exist only as an exogenous additive in the product, failing to deeply couple with the microbial metabolism during acetic acid fermentation. This results in a limited range of functional factors, and the discarded astragalus solids after liquid extraction lead to resource waste.

[0005] Thirdly, there are different methods of adding astragalus powder during the koji-making process. Some techniques involve directly mixing astragalus powder into daqu (large koji) or bran koji for cultivation and then using the medicinal koji instead of ordinary koji for vinegar fermentation. Although this method incorporates astragalus into the microbial culture system, the koji-making stage is a low-temperature, medium-humidity environment. At low temperatures, the cellulose and lignin of astragalus hardly degrade, and the astragalus in the koji material essentially exists only as a filler, without achieving true "fermentation transformation."

[0006] Furthermore, existing technologies generally treat Astragalus membranaceus as a simple "functional component carrier," neglecting and failing to consider its potential physical structural role in solid-state fermentation systems. The core difference between solid-state and liquid-state fermentation lies in the mass and heat transfer characteristics of the solid-liquid-gas three-phase interface, and the spatial structure and fiber properties of the excipients directly affect the quality of this interface. None of the aforementioned existing technologies have recognized or utilized the potential value of Astragalus membranaceus fiber at this level.

[0007] In summary, existing technologies generally rely on external enzyme preparations or chemical interventions to address the challenges of incorporating Astragalus into vinegar, failing to solve the problem from the perspective of the inherent regulation of the fermentation system itself. This results in redundant processes, high energy consumption, and a deviation from the traditional natural process concept of solid-state vinegar brewing. Summary of the Invention

[0008] This invention aims to provide a fully solid-state fermentation process for Astragalus membranaceus vinegar that does not rely on any exogenous enzyme preparations or chemical products. Without excessively increasing the complexity of the process, it simultaneously achieves the following objectives: natural degradation of Astragalus membranaceus lignocellulose and full release of active ingredients; synergistic transformation of Astragalus membranaceus' unique medicinal aroma with acetic acid to form a mellow and rich complex flavor; stable acid production during fermentation, simple operation, and suitability for large-scale production.

[0009] To achieve the above objectives, the present invention provides the following technical solution: A fully solid-state fermentation process for astragalus vinegar includes the following steps: S1: Take the rhizome of Astragalus membranaceus, slice it obliquely along the fiber direction, wash it and drain it naturally until the moisture content is 18%-22%; S2: Take sorghum, crush it, add water to soak it, and steam it under normal pressure. Add the astragalus slices treated in S1 between the 20th and 25th minute after the start of steaming. Continue steaming for a total time of 40 to 60 minutes. After the steaming is finished, spread it out to cool. You will get steamed sorghum and moistened astragalus slices. S3: The cooked sorghum is mixed with rice bran and the first grain size of rice husk, and then the first part of Daqu is added for alcoholic fermentation. The alcoholic fermentation is controlled by temperature variation. The material is turned over once every 24 hours during the fermentation process. After the fermentation is completed, the mash is obtained. The Astragalus membranaceus slices mentioned above do not participate in the S3 alcoholic fermentation. S4: Mix the mash obtained in S3 with the remaining Daqu, wheat bran, second-grade rice husks, and the astragalus slices obtained in S2 after moist heat softening. Adjust the moisture content to 60%-65% of the initial moisture content and then carry out acetic acid fermentation. Acetic acid fermentation includes a temperature adaptation period, a main fermentation period, and a post-ripening stabilization period. During the main fermentation period, the temperature is controlled at 39℃-41℃. During the fermentation process, the material is turned at a set frequency. When the acidity reaches 5.0g / 100mL-6.0g / 100mL and the acidity increase is less than 0.1g / 100mL in two consecutive tests, the acetic acid fermentation is terminated. S5: After the acetic acid fermentation is completed, the material is aged in situ in a closed state. During the aging period, the closed state is opened every 5 days to allow the material to be exposed to air for 15 to 20 minutes. The total aging time is 15 to 25 days. S6: After aging, vinegar is obtained by gradient temperature difference leaching, thus completing the solid-state fermentation of Taiwan Astragalus vinegar.

[0010] Preferably, the oblique cutting angle of the Astragalus membranaceus slices in S1 is 30°-45°, and the slice thickness is 1.5cm-2.5cm.

[0011] As a preferred embodiment, the temperature regulation described in S3 is as follows: the product temperature is controlled at 28℃-30℃ for the first 3 days of fermentation, at 32℃-35℃ for the 4th to 6th days, and at 28℃-30℃ for the 7th to 8th days.

[0012] Preferably, in S3, the particle size of the first-sized rice husk is 0.8mm-2.5mm, and in S4, the particle size of the second-sized rice husk is 2.5mm-4.0mm.

[0013] Preferably, in step S4, the temperature during the warming adaptation period is controlled to gradually increase from 28℃-32℃ to 38℃-40℃ for 3 days, with the material turned over every 12 hours; during the main fermentation period, the temperature is maintained at 39℃-41℃ for 5 days, with the material turned over every 8 hours; and during the post-ripening stabilization period, the temperature naturally decreases to 34℃-36℃ for 4 days, with the material turned over every 12 hours.

[0014] Preferably, in S3, the amount of the first part of Daqu used is 60%-70% of the total amount of Daqu, and in S4, the amount of the remaining Daqu used is 30%-40% of the total amount of Daqu.

[0015] As a preferred embodiment, the gradient temperature difference leaching method described in S6 is as follows: the first leaching uses hot water at 80℃-85℃, with an addition amount of 0.8 to 1.0 times the total weight of the material, and the leachate is collected after soaking for 4 to 6 hours; the second leaching uses warm water at 50℃-60℃, with an addition amount of 0.5 to 0.8 times the total weight of the material, and the leachate is collected after soaking for 3 to 4 hours; the third leaching uses cold water at 20℃-25℃, with an addition amount of 0.5 times the total weight of the material, and the leachate is collected after soaking for 2 to 3 hours; the three leachates are then combined.

[0016] As a preferred option, the weight ratio of each raw material is as follows: 100-120 parts sorghum, 8-15 parts Astragalus membranaceus tablets, 15-20 parts rice bran, 80-100 parts wheat bran, 60-80 parts rice husk, and 30-40 parts Daqu (a type of starter culture).

[0017] Preferably, the cooking in S2 is atmospheric pressure cooking, and the natural draining in S1 is carried out in an environment of 20℃-25℃.

[0018] Preferably, the initial moisture content of the mixture after adjustment in S4 is 60%-65%.

[0019] The technical effects and advantages of this invention are as follows: Compared with the prior art, the present invention has the following beneficial effects: This invention completely abandons the existing chemical methods of pretreating Astragalus membranaceus using cellulase, pectinase, or weak alkaline solutions. By adding Astragalus membranaceus slices during a specific time window (20-25 minutes after the start of cooking) in step S2, the sorghum has already undergone preliminary starch gelatinization, the free liquid water content in the cooking environment is reduced, and the humid heat atmosphere is dominated by saturated steam. The Astragalus membranaceus slices undergo humid heat softening in an environment dominated by gas-phase heat conduction, causing the hydrogen bonds between the internal fiber bundles to loosen and the fiber micropores to expand, preventing premature loss of water-soluble saponins due to prolonged immersion in boiling liquid water. Simultaneously, in step S4, the temperature during the main acetic acid fermentation period is precisely controlled between 39℃ and 41℃. This temperature range is not only the optimal temperature range for solid-state fermentation of acetic acid bacteria but also allows the residual cellulase and hemicellulase in the koji (fermentation starter) to retain some activity. Therefore, without adding any exogenous enzyme preparations, the endogenous enzyme activity of the solid-state fermentation system is used to achieve "simultaneous fermentation and self-degradation" of Astragalus membranaceus fibers, resulting in a greener process and lower cost.

[0020] This invention precisely couples the fiber degradation of Astragalus membranaceus slices with acetic acid fermentation in terms of time and space. In the S3 alcoholic fermentation stage, the Astragalus membranaceus slices do not participate in fermentation, preventing the flavonoid glycoside precursors in Astragalus membranaceus from being metabolized by yeast into secondary products with unpleasant bitterness under an anaerobic reducing atmosphere, thus blocking the bitterness generation pathway at the source of the process. In the S4 acetic acid fermentation stage, as the acidity gradually accumulates from the initial level to 5.0g / 100mL-6.0g / 100mL, the acidity of the environment in which the Astragalus membranaceus slices are located gradually increases. Astragalus saponins undergo deacetylation and deglycosylation reactions in the acidic environment, transforming into more easily absorbed secondary saponins. Simultaneously, the Astragalus polysaccharides produced from fiber degradation undergo Maillard reactions with amino acids in the vinegar mash at temperatures of 39℃-41℃, forming caramel color and a unique roasted aroma, giving the final product a unique flavor profile.

[0021] This invention implements particle size distribution management for the same auxiliary material, rice husks, based on differences in fermentation stages. In the S3 alcoholic fermentation stage, fine rice husks with a particle size of 0.8mm-2.5mm are used. Fine rice husks have a large specific surface area and strong water retention, which is beneficial for maintaining the appropriate water activity required for yeast metabolism during alcoholic fermentation. In the S4 acetic acid fermentation stage, medium-coarse rice husks with a particle size of 2.5mm-4.0mm are used. Medium-coarse rice husks have good structural strength and strong aeration, effectively increasing the porosity inside the vinegar mash, improving oxygen transfer efficiency, and meeting the dissolved oxygen requirements of acetic acid bacteria's aerobic metabolism. Simultaneously, the Astragalus membranaceus slices, after undergoing S2 moist heat softening treatment, maintain their natural fibrous skeleton structure during the acetic acid fermentation stage, forming a synergistic three-dimensional aeration network with the medium-coarse rice husks, further optimizing the aeration and mass transfer conditions of the vinegar mash. This design, without changing the total raw material ratio, precisely matches the contradictory requirements of anaerobic yeast fermentation and aerobic acetic acid bacteria fermentation for material compactness and permeability through differentiated use of physical parameters, improving fermentation efficiency and acid production stability.

[0022] This invention achieves efficient release and flavor transformation of Astragalus membranaceus functional components through a series of purely physical methods and endogenous microbial metabolic regulation within the fermentation system, including moisture content control in S1, cooking timing intervention in S2, rice husk particle size classification in S3 and S4, temperature threshold setting in S4, intermittent micro-aerobic aging in S5, and gradient temperature leaching in S6. The process is simple to operate, with highly controllable parameters, making it easy to directly implement on existing solid-state vinegar production lines and demonstrating promising prospects for industrial application. Attached Figure Description

[0023] Fig. 1 This is a flowchart of the process preparation of the present invention.

[0024] Fig. 2 This is a schematic diagram illustrating the principle of wet heat softening treatment and cooking time control in this invention. Detailed Implementation

[0025] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention. Example 1

[0026] As attached Figs. 1-2 As shown in the figure, this embodiment provides a fully solid-state fermentation process for astragalus vinegar, and the specific steps are as follows: S1: Take dried, authentic Astragalus membranaceus rhizomes, cut them into slices with a thickness of 2.0 cm at a 30° angle along the fiber growth direction, quickly rinse with clean water to remove surface adhering substances, and then place them in a 20°C naturally ventilated environment to drain. Use a halogen moisture analyzer to monitor the moisture content in real time. Stop draining when the moisture content stabilizes and drops to 20%, and you will get pretreated Astragalus membranaceus slices.

[0027] S2: Take 110 kg of sorghum and crush it to a particle size that can pass through a 30-mesh sieve. Soak it in water for 7 hours to allow it to fully absorb water and swell. Place the soaked sorghum in a normal pressure steaming environment for steaming. At the 23rd minute after the start of steaming, add 12 kg of pretreated Astragalus membranaceus slices obtained in S1 to the steaming environment at once, and continue steaming together with the sorghum. Stop steaming after the total steaming time reaches 50 minutes. Take out the steamed sorghum and Astragalus membranaceus slices separately, and quickly spread them out in a clean environment to cool to 32°C, obtaining steamed sorghum and moistened softened Astragalus membranaceus slices.

[0028] S3: Take the cooked sorghum obtained from S2, mix it evenly with 18kg of rice bran and 35kg of first-grade rice husks (sieved to a particle size of 1.5mm), add 65% of the total amount of Daqu (i.e., 22.75kg, the total amount of Daqu is 35kg), stir evenly, and then enter the alcoholic fermentation stage.

[0029] Alcoholic fermentation employs variable temperature control: the temperature is maintained at 29℃ for the first 3 days; from day 4 to day 6, the temperature is allowed to rise naturally and controlled at 33℃; from day 7 to day 8, the temperature is controlled to drop back to 29℃ for post-fermentation. During fermentation, the material is turned over every 24 hours. Alcoholic fermentation is terminated when the volume concentration of alcohol in the fermented mash reaches 5.8%, yielding mature mash. Astragalus membranaceus slices are not involved in this fermentation process.

[0030] S4: Mix the mature mash obtained from S3 with the remaining 12.25 kg of Daqu (35% of the total Daqu content), 90 kg of wheat bran, 35 kg of second-grade rice husks (sieved to a particle size of 3.0 mm), and the astragalus slices obtained from S2 after moist heat softening. Stir well and add water to adjust the initial absolute moisture content of the materials to 62%. Acetic acid fermentation is divided into three stages: Temperature adaptation period: Control the temperature to be increased from 30℃ to 39℃ at a uniform rate for 3 days, and turn the material once every 12 hours. Main fermentation period: Maintain the product temperature at 40℃ for 5 days, turning the feed once every 8 hours; Post-ripening stabilization period: Stop active heating and allow the product temperature to naturally decrease to 35℃ for 4 days, turning the feed once every 12 hours.

[0031] Acetic acid fermentation is terminated when the acidity of the material reaches 5.5 g / 100 mL (calculated as acetic acid) and the acidity increase between two consecutive tests is 0.06 g / 100 mL (less than 0.1 g / 100 mL).

[0032] S5: The material after acetic acid fermentation is not transferred, but aged in situ in a sealed environment isolated from external air. The total aging time is 20 days, during which the sealed state is opened once every 5 days to allow the material to come into contact with the outside air for 18 minutes before being sealed again.

[0033] S6: After aging, the vinegar solution is extracted using a gradient temperature difference leaching method. First vinegar rinsing: Use 83℃ hot water, add 0.9 times the total weight of the material, soak for 5 hours and collect the first vinegar rinsing liquid; Second vinegar rinsing: Use 55℃ warm water, add 0.6 times the total weight of the material, soak for 3.5 hours and collect the second vinegar rinsing liquid; Third vinegar rinsing: Use 22℃ cold water, add 0.5 times the total weight of the material, soak for 2.5 hours and collect the third vinegar rinsing liquid.

[0034] The three leachates are combined and allowed to settle and clarify naturally to obtain the finished product, astragalus vinegar, which is a fully solid-state fermented product. Example 2

[0035] In this embodiment, the parameters are the lower limit of the scope of protection of the claims. The specific steps are as follows: S1: Take the rhizome of Astragalus membranaceus and cut it into slices with a thickness of 1.5cm at a 30° angle along the fiber direction. After washing, let it drain naturally at 20°C until the moisture content is 18%.

[0036] S2: Take 100kg of sorghum, grind it to 30 mesh, soak it in water for 6 hours, and steam it under normal pressure. Add 8kg of Astragalus membranaceus slices 20 minutes after the steaming begins, and continue steaming for a total of 40 minutes. Spread it out to cool after steaming.

[0037] S3: After steaming, 15 kg of sorghum and rice bran, and 30 kg of first-grade rice husks (sieved to a particle size of 0.8 mm) are mixed together, and 60% of the total amount of Daqu (30 kg of Daqu, i.e., 18 kg) is added for alcoholic fermentation. Temperature control: The temperature is 28℃ for the first 3 days, 32℃ for days 4 to 6, and 28℃ for days 7 to 8. The mixture is turned over every 24 hours. Astragalus membranaceus tablets are not used in this stage.

[0038] S4: Mix the mature mash with 12kg of remaining Daqu (fermented starter culture), 80kg of wheat bran, 30kg of second-grade rice husks (sieved to a particle size of 2.5mm), and softened Astragalus membranaceus slices (prepared by moist heat), adjusting the moisture content to 60%. Acetic acid fermentation: During the adaptation period, gradually increase the temperature from 28℃ to 38℃ for 3 days, turning the mash every 12 hours; maintain the temperature at 39℃ during the main fermentation period for 5 days, turning the mash every 8 hours; during the post-ripening stabilization period, allow the temperature to drop naturally to 34℃ for 4 days, turning the mash every 12 hours. The fermentation process ends when the acidity reaches 5.0g / 100mL and the increase is less than 0.1g / 100mL.

[0039] S5: Aged in situ for 15 days, with ventilation for 15 minutes every 5 days.

[0040] S6: Gradient temperature difference leaching: First, soak in 80℃ hot water (0.8 times the weight of the material) for 4 hours; second, soak in 50℃ warm water (0.5 times the weight of the material) for 3 hours; third, soak in 20℃ cold water (0.5 times the weight of the material) for 2 hours. Combine the leachates to obtain the final product. Example 3

[0041] In this embodiment, the parameters are taken from the upper limit of the scope of protection of the claims. The specific steps are as follows: S1: Take the rhizome of Astragalus membranaceus and cut it into slices with a thickness of 2.5cm at a 45° angle along the fiber direction. After washing, let it drain naturally at 25°C until the moisture content is 22%.

[0042] S2: Take 120kg of sorghum, grind it to 40 mesh, soak it in water for 8 hours, and steam it under normal pressure. Add 15kg of Astragalus membranaceus slices 25 minutes after the steaming begins, and continue steaming for a total of 60 minutes. Spread it out to cool after steaming.

[0043] S3: After steaming, 20 kg of sorghum and rice bran, and 40 kg of first-grade rice husks (sieved to a particle size of 2.5 mm) are mixed together, and 70% of the total amount of Daqu (total Daqu 40 kg, i.e., 28 kg) is added for alcoholic fermentation. Temperature control: 30℃ for the first 3 days, 35℃ for days 4-6, and 30℃ for days 7-8, turning the mixture every 24 hours. Astragalus membranaceus tablets are not used in this stage.

[0044] S4: Mix the mature mash with 12kg of remaining Daqu (fermented starter culture), 100kg of wheat bran, 40kg of second-grade rice husks (sieved to a particle size of 4.0mm), and softened Astragalus membranaceus slices (prepared by moist heat), adjusting the moisture content to 65%. Acetic acid fermentation: During the adaptation period, gradually increase the temperature from 32℃ to 40℃ for 3 days, turning the mash every 12 hours; maintain the temperature at 41℃ during the main fermentation period for 5 days, turning the mash every 8 hours; during the post-ripening stabilization period, allow the temperature to drop naturally to 36℃ for 4 days, turning the mash every 12 hours. The fermentation process ends when the acidity reaches 6.0g / 100mL and the increase is less than 0.1g / 100mL.

[0045] S5: Aged in situ for 25 days, with aeration for 20 minutes every 5 days.

[0046] S6: Gradient temperature difference leaching: First, soak in 85℃ hot water (1.0 times the weight of the material) for 6 hours; second, soak in 60℃ warm water (0.8 times the weight of the material) for 4 hours; third, soak in 25℃ cold water (0.5 times the weight of the material) for 3 hours. Combine the leachates to obtain the final product.

[0047] Comparative Example 1 This comparative example uses a process of pretreating Astragalus membranaceus with added enzymes. Astragalus membranaceus slices were spray-hydrolyzed with an enzyme solution containing 500 U / g cellulase and 300 U / g pectinase. The hydrolysis temperature was 45℃ and the hydrolysis time was 2 hours. The enzymatically hydrolyzed astragalus and sorghum were steamed in layers for a total of 60 minutes. Alcoholic fermentation and acetic acid fermentation were carried out in stages with controlled temperature, with the acetic acid fermentation temperature controlled at 38℃-40℃. The mixture was aged for 15 days and then diluted with vinegar. The remaining raw material ratios and steps not detailed were the same as in Example 1.

[0048] Comparative Example 2 In this comparative example, the Astragalus membranaceus slices were not subjected to the S2 moist heat softening treatment. The Astragalus membranaceus slices were directly treated according to S1 in Example 1 (slicing, washing, and draining to a moisture content of 20%), but were not involved in the S2 cooking. In the S4 acetic acid fermentation stage, the Astragalus membranaceus slices that had not undergone moist heat softening were directly mixed with mash, bran, rice husks, etc., for acetic acid fermentation. The remaining steps were exactly the same as in Example 1.

[0049] Comparative Example 3 In this comparative example, the Astragalus membranaceus slices from Taiwan participated in the alcoholic fermentation stage. After being treated according to S1 and S2 in Example 1, the Astragalus membranaceus slices were mixed with steamed sorghum, rice bran, rice husks, and Daqu (a type of starter culture) in the S3 alcoholic fermentation stage for alcoholic fermentation. The subsequent acetic acid fermentation, aging, and vinegar extraction steps were exactly the same as in Example 1.

[0050] Comparative Example 4 In this comparative example, the temperature during the main fermentation stage of acetic acid fermentation exceeded the scope of protection of the claims. Steps S1 to S3 and S5 to S6 were exactly the same as in Example 1. During S4 acetic acid fermentation, the temperature during the main fermentation stage was controlled at 43℃-45℃, and the remaining parameters were the same as in Example 1.

[0051] Comparative Example 5 In this comparative example, the temperature during the main fermentation stage of acetic acid fermentation was lower than the scope of protection of the claims. Steps S1 to S3 and S5 to S6 were exactly the same as in Example 1. During S4 acetic acid fermentation, the temperature during the main fermentation stage was controlled at 35℃-37℃, and the remaining parameters were the same as in Example 1.

[0052] Product performance testing The following indicators were tested on the Astragalus vinegar products obtained in each embodiment and comparative example: Detection method: Total acid content: determined according to the method specified in GB12456-2021 "National Food Safety Standard - Determination of Total Acid in Food"; Astragaloside A content: determined by high performance liquid chromatography. The chromatographic conditions were: C18 column (250 mm × 4.6 mm, 5 μm), mobile phase acetonitrile-water (32:68), flow rate 1.0 mL / min, and detection wavelength 203 nm. Total flavonoid content: determined by NaNO2-Al(NO3)3-NaOH colorimetric method and ultraviolet spectrophotometry at a wavelength of 510 nm; Total polysaccharide content: determined by the phenol-sulfuric acid method at a wavelength of 490 nm; Sensory evaluation: An evaluation panel of 10 professionals with experience in vinegar tasting will give a comprehensive score based on three dimensions: color, aroma, and taste, with a maximum score of 10 points.

[0053] Test results: Results analysis: Comparison of Examples 1 and Comparative Example 1: In Examples 1-3, without the use of any exogenous enzyme preparations, the contents of astragaloside A, total flavonoids, and total polysaccharides were comparable to those of Comparative Example 1, and the sensory scores were superior. This demonstrates that the present invention achieves the same functional component release effect as exogenous enzyme methods through process timing control and temperature threshold setting, while avoiding the introduction of exogenous enzymes.

[0054] Comparison of Examples and Comparative Example 2: Comparative Example 2 lacked the S2 moist heat softening step, and the astragalus fiber was not properly pre-relaxed, resulting in a significantly lower dissolution rate of functional components compared to the examples, and the product had a noticeable bitter taste. This demonstrates that the S2 moist heat softening treatment is a necessary prerequisite for achieving simultaneous self-degradation of astragalus fiber.

[0055] Comparison of Example 1 and Comparative Example 3: In Comparative Example 3, Astragalus membranaceus tablets participated in alcoholic fermentation, resulting in a more pronounced bitter taste and lower content of functional components compared to Example 2. This indicates that limiting Astragalus membranaceus participation to the acetic acid fermentation stage can effectively block the formation of bitter precursor substances under anaerobic conditions.

[0056] Comparison of Example 4 and Comparative Example 5: Comparative Example 4 reached a main fermentation temperature of 43℃-45℃, exceeding the optimal growth temperature range for acetic acid bacteria, resulting in a significant decrease in total acid content and a reduction in astragaloside A content. This demonstrates that the temperature range of 39℃-41℃ is an optimized parameter that balances acid production efficiency and the retention of functional components.

[0057] Comparison of Example 5 and Comparative Example 5: In Comparative Example 5, the main fermentation temperature was only 35℃-37℃, resulting in a lower acid production rate of acetic acid bacteria, insufficient endogenous cellulase activity, and a lower dissolution rate of functional components compared to Example 5. This demonstrates that the temperature range of 39℃-41℃ plays a crucial role in activating the endogenous enzyme system and achieving synchronous self-degradation.

[0058] Scope verification of the embodiments: Both Embodiment 2 and Embodiment 3 can be successfully implemented and qualified products can be obtained, proving that the parameter ranges defined in the claims are feasible and the scope of protection is reasonable.

[0059] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A fully solid-state fermentation process for astragalus vinegar, characterized in that, Includes the following steps: S1: Take the rhizome of Astragalus membranaceus, slice it obliquely along the fiber direction, wash it and drain it naturally until the moisture content is 18%-22%; S2: Take sorghum, crush it, add water to soak it, and steam it under normal pressure. Add the astragalus slices treated in S1 between the 20th and 25th minute after the start of steaming. Continue steaming for a total time of 40 to 60 minutes. After the steaming is finished, spread it out to cool. You will get steamed sorghum and moistened astragalus slices. S3: The cooked sorghum is mixed with rice bran and the first grain size of rice husk, and then the first part of Daqu is added for alcoholic fermentation. The alcoholic fermentation is controlled by temperature variation. The material is turned over once every 24 hours during the fermentation process. After the fermentation is completed, the mash is obtained. The Astragalus membranaceus slices mentioned above do not participate in the S3 alcoholic fermentation. S4: Mix the mash obtained in S3 with the remaining Daqu, wheat bran, second-grade rice husks, and the astragalus slices obtained in S2 after moist heat softening. Adjust the moisture content to 60%-65% of the initial moisture content and then carry out acetic acid fermentation. Acetic acid fermentation includes a temperature adaptation period, a main fermentation period, and a post-ripening stabilization period. During the main fermentation period, the temperature is controlled at 39℃-41℃. During the fermentation process, the material is turned at a set frequency. When the acidity reaches 5.0g / 100mL-6.0g / 100mL and the acidity increase is less than 0.1g / 100mL in two consecutive tests, the acetic acid fermentation is terminated. S5: After the acetic acid fermentation is completed, the material is aged in situ in a closed state. During the aging period, the closed state is opened every 5 days to allow the material to be exposed to air for 15 to 20 minutes. The total aging time is 15 to 25 days. S6: After aging, vinegar is obtained by gradient temperature difference leaching, thus completing the solid-state fermentation of Taiwan Astragalus vinegar.

2. The all-solid-state fermentation process for astragalus vinegar according to claim 1, characterized in that, The oblique cutting angle of the Astragalus membranaceus slices described in S1 is 30°-45°, and the slice thickness is 1.5cm-2.5cm.

3. The all-solid-state fermentation process for astragalus vinegar according to claim 1, characterized in that, The specific temperature control described in S3 is as follows: the product temperature is controlled at 28℃-30℃ for the first 3 days of fermentation, 32℃-35℃ for the 4th to 6th days, and 28℃-30℃ for the 7th to 8th days.

4. The all-solid-state fermentation process for astragalus vinegar according to claim 1, characterized in that, In S3, the particle size of the first-sized rice husk is 0.8mm-2.5mm, and in S4, the particle size of the second-sized rice husk is 2.5mm-4.0mm.

5. The all-solid-state fermentation process for astragalus vinegar according to claim 1, characterized in that, During the temperature rise adaptation period described in S4, the product temperature is gradually increased from 28℃-32℃ to 38℃-40℃ for 3 days, with the material turned over every 12 hours; during the main fermentation period, the product temperature is maintained at 39℃-41℃ for 5 days, with the material turned over every 8 hours; during the post-ripening stabilization period, the product temperature naturally drops to 34℃-36℃ for 4 days, with the material turned over every 12 hours.

6. The all-solid-state fermentation process for astragalus vinegar according to any one of claims 1-5, characterized in that, In S3, the amount of Daqu used in the first part is 60%-70% of the total amount of Daqu, and in S4, the amount of Daqu used in the remaining part is 30%-40% of the total amount of Daqu.

7. The all-solid-state fermentation process for astragalus vinegar according to any one of claims 1-5, characterized in that, The gradient temperature difference leaching method described in S6 is as follows: For the first vinegar leaching, use hot water at 80℃-85℃, adding 0.8 to 1.0 times the total weight of the material. After soaking for 4 to 6 hours, collect the leaching liquid. For the second vinegar leaching, use warm water at 50℃-60℃, adding 0.5 to 0.8 times the total weight of the material. Soak for 3 to 4 hours, then collect the leaching liquid. For the third leaching of vinegar, use cold water at 20℃-25℃, adding 0.5 times the total weight of the material. Soak for 2-3 hours and then collect the leachate. Combine the leachates from the three leaching processes.

8. The all-solid-state fermentation process for astragalus vinegar according to any one of claims 1-5, characterized in that, The weight ratio of each raw material is as follows: 100-120 parts sorghum, 8-15 parts Astragalus membranaceus tablets, 15-20 parts rice bran, 80-100 parts wheat bran, 60-80 parts rice husk, and 30-40 parts Daqu (a type of starter culture).

9. The all-solid-state fermentation process for astragalus vinegar according to any one of claims 1-5, characterized in that, The cooking described in S2 is normal pressure cooking, and the natural drainage described in S1 is carried out in an environment of 20℃-25℃.

10. The all-solid-state fermentation process for astragalus vinegar according to claim 5, characterized in that, The initial moisture content of the mixture after adjustment in S4 is 60%-65%.

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