All-solid-state astragalus membranaceus vinegar fermentation process

Abstract

The invention belongs to the technical field of table vinegar fermentation, and particularly relates to an all-solid-state astragalus membranaceus vinegar fermentation process. The preparation method comprises the following steps: S1, performing soaking and enzymolysis pretreatment; s2, layered cooking and humidity gradient; s3, performing time-sharing inoculation on the mixed materials and the strains; s4, carrying out alcoholic fermentation; s5, acetic fermentation; s6, smoking and fermenting; s7, vinegar spraying; according to the process, the release efficiency of astragalus polysaccharide and a carbon source is remarkably improved through weak base enzymolysis and a segmented temperature and humidity control technology, mass transfer is enhanced by adopting a porous carrier, and stable fermentation is achieved in cooperation with mineral substance slow-release microcapsules; aroma precursors are generated step by step through the two-stage smoking and fermenting process, functional components and flavor substances are synchronously extracted through spraying circulation, and efficient fermentation and flavor collaborative optimization are achieved.

Description

Technical Field

[0001] The invention belongs to the technical field of vinegar fermentation, and particularly relates to a full-solid-state astragalus vinegar fermentation process. Background Art

[0002] Astragalus vinegar is a functional vinegar made through microbial fermentation using the edible and medicinal plant Astragalus as its core ingredient. It combines the sour and fragrant flavor of traditional vinegar with the unique health benefits of Astragalus, such as tonifying qi and strengthening the exterior, and enhancing immunity. Modern research shows that Astragalus is rich in active ingredients such as astragalus polysaccharides, astragalosides, and flavonoids, which possess antioxidant, immune-modulating, and anti-fatigue properties. Acetic acid fermentation not only imparts a mild sour flavor to the product but also promotes the conversion and release of active ingredients through microbial metabolism, forming more readily absorbed functional factors such as small-molecule polyphenols and organic acid-astragaloside complexes. Traditional Astragalus vinegar fermentation processes typically utilize liquid or semi-solid fermentation methods, often modified from grain-based vinegar brewing processes. While liquid fermentation facilitates industrial control, it suffers from low raw material bioconversion rates and lengthy fermentation cycles. This is particularly true when processing highly lignified medicinal and edible raw materials like Astragalus, where cellulose and lignin degradation is inefficient, limiting the dissolution of the Astragalus' active ingredients. The current process generally adopts high-temperature sterilization pretreatment, which can ensure the safety of fermentation, but it is easy to cause irreversible loss of heat-sensitive functional factors such as astragalus polysaccharides and astragaloside IV. Although the semi-solid process can partially retain the characteristics of the raw materials, the metabolic imbalance of the bacterial community often occurs during the collaborative fermentation of multiple strains, resulting in unstable production of flavor substances, and the juice often needs to be squeezed in the later stage of fermentation, resulting in waste of solids. Both types of processes require the separation of vinegar juice by filtration, resulting in a large amount of solids containing astragalus residues being discarded, which not only wastes resources but also loses bound functional components. Therefore, it is extremely necessary to explore a new, efficient and safe all-solid-state fermentation process. Summary of the Invention

[0003] In view of the defects of the prior art, the object of the present invention is to provide a full-solid-state astragalus vinegar fermentation process.

[0004] The technical effects of the present invention are achieved through the following technical solution: a fully solid-state astragalus vinegar fermentation process, comprising the following steps: S1: soaking and enzymatic pretreatment; S2: layered cooking with humidity gradient; S3: Mixing materials and inoculating bacteria at different times; S4: alcoholic fermentation; S5: acetic acid fermentation; S6: smoked mash; S7: Drizzle with vinegar; Preferably, in step S1, the specific operations of the soaking material and enzymatic pretreatment are as follows: S101: The crushed sorghum, astragalus powder and lees are mixed in a mass ratio of 10:1:30, a pre-prepared slow-release enzyme solution is added, and the mixture is soaked in water for 10 to 12 hours. During this stage, the pH is maintained at 8.0 and the temperature is maintained at 40 to 45°C. The moisture content of the slurry reaches 60 to 65%, thereby obtaining a soaked material; Preferably, in step S101, the slow-release enzyme solution is prepared by adding 0.5% cellulase and 0.3% pectinase to a phosphate buffer solution preheated at 40°C, stirring and dissolving the mixture uniformly, and then standing at 45°C for 10 minutes; the cellulase activity is 5×10 4 U / g; the pectinase activity is 10 5 U / g; Preferably, in step S2, the specific operations of the layered cooking and humidity gradient are as follows: S201: Add equal amounts of the soaking material from step S101 into a steamer in three layers, spray each layer with moisture before steaming, and steam in stages for 90 minutes to obtain steamed material; Preferably, in step S201, the specific operation of the staged cooking is: the first stage is 30 minutes, the humidity is 65%, and the temperature is 100°C; the middle stage is 30 minutes, the humidity is 60%, and the temperature is 100°C; the last stage is 30 minutes, the humidity is 55%, and the temperature is 100°C; Preferably, in step S3, the specific operations of mixing the materials and inoculating the strains at different times are as follows: S301: When the steamed material in step S201 is cooled to 50° C., 40% of the mass of Daqu and 20% of the mass of Wenqu are added, the mixture is evenly mixed, the temperature is lowered to 25° C., 3-5% of thermophilic yeast is inoculated, and pre-fermentation is carried out for 12 hours. 1-2% of acetic acid bacteria is spray-inoculated to obtain a mixed material; Preferably, in step S4, the specific operation of the alcohol fermentation is as follows: S401: Add the mixture from step S301 to an alcohol fermentation tank, sprinkle rice husks and bamboo charcoal powder on the surface, cover with bran and plastic sheeting to seal, and ferment in stages. After fermentation, measure the alcohol content of the mash to determine if it is between 3.5% and 6.5%, thereby obtaining an alcohol fermented mash. Preferably, in step S401, the mass ratio of the rice husk to the bamboo charcoal powder is 4 to 6:1; Preferably, in step S401, the specific operation of the staged fermentation is: on the 1st to 2nd day, the temperature is controlled at 32-35°C, on the 3rd to 8th day, the temperature is controlled at 23-25°C, and the pH is controlled at 6.0-6.5; Preferably, in step S5, the specific operation of the acetic acid fermentation is as follows: S501: taking the alcohol fermentation mash from step S401, mixing it with 20% of the main material weight of rice husk, 100-110% of bran, 0.5-1% of diatomaceous earth, and 0.1-0.3% of a slow-release mineral bag, placing it in an acetic acid fermentation tank, covering it with a breathable straw mat, and fermenting it in stages to obtain acetic acid mash; Preferably, in step S501, the specific preparation steps of the mineral sustained-release package are as follows: S1001: Dissolve potassium dihydrogen phosphate, magnesium sulfate, zinc sulfate, iron sulfate, manganese sulfate, and copper sulfate in deionized water, and stir for 20 minutes to obtain a mineral solution; S1002: Dissolve food-grade hydroxypropyl methylcellulose and chitosan in 1.5% acetic acid water and spray dry at 75°C to obtain hollow microspheres; then add the hollow microspheres to the mineral solution of step S1001, circulate adsorption at 60°C for 30-60 minutes, and then remove to obtain adsorbed microspheres; S1003: Add the adsorbed microspheres from step S1002 to a 0.2% sodium alginate solution and disperse them evenly. Then, dropwise add a 1.5% CaCl2 solution. After cross-linking treatment for 15 to 20 minutes, remove the microspheres, vacuum dry them at 40°C for 12 to 16 hours, crush them, and filter through a 16-mesh screen to obtain a mineral sustained-release package. Preferably, in step S1001, the mass ratio of the potassium dihydrogen phosphate, magnesium sulfate, zinc sulfate, iron sulfate, manganese sulfate and copper sulfate is 46:30:12:6:3:3; Preferably, in step S1002, the ratio of the amount of hydroxypropyl methylcellulose, chitosan and acetic acid water is 4g:1g:40-50mL; Preferably, in step S1002, the ratio of the amount of the hollow microspheres to the mineral solution is 1 g: 5-8 mL; Preferably, in step S1003, the ratio of the amount of the adsorption microspheres, the sodium alginate solution and the CaCl2 solution is 1 g: 4.5-5.5 mL: 5.5-6.5 mL; Preferably, in step S501, the specific operation of the staged fermentation is: on the 1st to 4th day, the temperature is controlled at 45-48°C, and the vat is turned over once every 12 hours; on the 5th to 7th day, the temperature is controlled at 42-44°C, and the vat is turned over once every 24 hours; on the 8th to 9th day, the temperature is controlled at 38-40°C, and the vat is turned over once every 24 hours; Preferably, in step S6, the specific operation of smoking the mash is as follows: S601: Add the acetic acid mash material from step S501 into a mash smoking tank, dry-smoking at 45-50° C. and controlling the humidity at 35-40% on the first to second days, and wet-smoking at 35-40° C. and controlling the humidity at 65-70% on the third to fifth days to obtain a smoked mash; Preferably, in step S601, the smoke source used in the dry smoking is obtained by mixing bran husks and buckwheat husks in a mass ratio of 3:1; the smoke source used in the wet smoking is obtained by mixing bran husks, fruit sawdust and astragalus stem and leaf powder in a mass ratio of 2:1:0.05; Preferably, in step S7, the specific operation of pouring vinegar is as follows: S701: Place the smoked mash into a rinsing device, and circulate water spraying and pouring for 60 minutes to obtain astragalus vinegar.

[0005] The beneficial effects of the present invention are as follows: The process of the present invention adds cellulase and pectinase in a weakly alkaline environment, combined with warm soaking, to partially loosen the cell walls of astragalus and sorghum, significantly improving the availability of polysaccharides and soluble carbon sources; at the same time, the uniform moisture content in the initial stage provides more consistent heat transfer conditions for the subsequent heat treatment stage, thereby ensuring that starch and cellulose can be fully gelatinized and enzymatically hydrolyzed, laying the material foundation for efficient fermentation. Segmented cooking and staged fermentation form different gradients in the three dimensions of humidity, temperature and pH, respectively, providing optimal conditions for different enzyme systems and bacterial communities in space and time; first, the high humidity and high temperature stage promotes gelatinization and initial saccharification, then the medium temperature and medium humidity stage balances the saccharification and fermentation rates, and finally, the late low humidity and low temperature stage is conducive to the accumulation and maintenance of aroma precursors. In addition, the slow transition of pH from slightly alkaline to weakly acidic forms a closed loop through potassium carbonate spraying and tank turning to supplement oxygen, so that the activity and metabolic direction of the bacterial community in each stage can be precisely controlled, avoiding common bacterial competition and by-product accumulation. During the acetic acid fermentation stage, porous carriers (rice husks, bamboo charcoal, diatomaceous earth) are introduced to construct a pore network, enhance the mass transfer efficiency of gases and liquids, and ensure that oxygen and substrates can be evenly distributed to the microbial population; mineral microcapsules made of chitosan-hydroxypropyl methylcellulose are used to achieve the continuous release of metal ions such as magnesium, zinc, and iron, and maintain the stability of the key enzyme activities of acetic acid bacteria. The two-stage fumigation process achieves the step-by-step release and transformation of volatile aromatic substances by successively adjusting the temperature, humidity, and fumigation source combination: the dry fumigation stage is mainly based on thermal cracking and Mena reaction to generate primary aroma precursors; the wet fumigation stage uses water vapor carriers to promote the infiltration and fixation of volatile oils of medicinal materials, thereby enhancing the layering of aroma. The subsequent leaching cycle process uses the adsorption and desorption characteristics of the porous carrier to match the migration rates of polysaccharides and volatile esters, thereby simultaneously extracting functional components and aromatic components, improving the overall flavor complexity and functionality of the product. BRIEF DESCRIPTION OF THE DRAWINGS

[0006] In order to more clearly illustrate the technical solutions in the present invention or the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only for the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0007] Figure 1 3 and 4. It is a graph showing the total acid content and pH measurement results of the astragalus vinegar brewed in Example 3 of the present invention, Comparative Examples 1-2, and the control group (brewing using a conventional semi-solid process). DETAILED DESCRIPTION

[0008] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention. It should be noted that unless otherwise specified, the raw materials involved in the present invention were purchased through conventional commercial channels.

[0009] Example 1: A fully solid-state astragalus vinegar fermentation process comprising the following steps: S1: soaking and enzymatic pretreatment; S101: The crushed sorghum, astragalus powder and lees were mixed in a mass ratio of 10:1:30, and a pre-prepared slow-release enzyme solution was added. The mixture was soaked in water for 12 hours, with the pH at 8.0 and the temperature at 40°C maintained during this stage. The moisture content of the lees was initially adjusted to 60%, thereby obtaining a soaked material. The slow-release enzyme solution is prepared by adding 0.5% cellulase and 0.3% pectinase to a phosphate buffer solution preheated at 40°C, stirring and dissolving uniformly, and then standing at 45°C for 10 minutes; the cellulase activity is 5×10 4 U / g; the pectinase activity is 10 5 U / g; S2: layered cooking with humidity gradient; S201: Add equal amounts of the soaking material from step S101 into a steamer in three layers. Spray each layer with moisture before steaming. Steam in stages: the first stage (30 minutes), humidity (65%), temperature (100°C); the middle stage (30 minutes), humidity (60%), temperature (100°C); and the last stage (30 minutes), humidity (55%), temperature (100°C). S3: Mixing materials and inoculating bacteria at different times; S301: When the steamed material in step S201 is cooled to 50° C., 40% of the mass of the main material, Daqu, and 20% of the mass of the main material, Wenqu, are added, mixed, cooled to 25° C., inoculated with 3% of thermophilic yeast, pre-fermented for 12 hours, and spray-inoculated with 1% of acetic acid bacteria to obtain a mixed material; S4: alcoholic fermentation; S401: Add the mixed material from step S301 to an alcohol fermentation tank, sprinkle rice husks and bamboo charcoal powder on the surface, cover with bran and plastic sheeting to seal, and ferment in stages. On days 1 to 2, the temperature is controlled at 32°C, and on days 3 to 8, the temperature is controlled at 23°C. The pH is controlled at 6.5. After fermentation, the alcohol content of the mash is measured and found to be 3.5%, thereby obtaining an alcohol fermented mash. S5: acetic acid fermentation; S501: Take the alcohol fermentation mash from step S401, mix it with 20% of the main material weight of rice husk, 100% of bran, 0.5% of diatomaceous earth and 0.1% of a slow-release mineral bag, place it in an acetic acid fermentation tank, cover it with a breathable straw mat, and ferment it in stages. On the 1st to 4th day, control the temperature at 45°C and turn the tank every 12 hours; on the 5th to 7th day, control the temperature at 42°C and turn the tank every 24 hours; on the 8th to 9th day, control the temperature at 38°C and turn the tank every 24 hours to obtain acetic acid mash; The specific preparation steps of the mineral sustained-release package are as follows: S1001: Dissolve 1.38 g of potassium dihydrogen phosphate, 0.9 g of magnesium sulfate, 0.36 g of zinc sulfate, 0.18 g of iron sulfate, 0.09 g of manganese sulfate, and 0.09 g of copper sulfate in 100 mL of deionized water and stir for 20 minutes to obtain a mineral solution; S1002: 8 g of food-grade hydroxypropyl methylcellulose and 2 g of chitosan were dissolved in 80 mL of 1.5% acetic acid water and spray-dried at 75°C to obtain hollow microspheres. 10 g of the hollow microspheres were then added to 50 mL of the mineral solution prepared in step S1001 and subjected to cyclic adsorption at 60°C for 30 min, followed by removal to obtain adsorbed microspheres. S1003: 10 g of the adsorption microspheres from step S1002 were added to 45 mL of 0.2% sodium alginate solution and dispersed evenly. 55 mL of 1.5% CaCl2 solution was then added dropwise. After cross-linking treatment for 15 minutes, the microspheres were removed, vacuum-dried at 40°C for 12 hours, crushed and screened through a 16-mesh filter to obtain a mineral sustained-release package. S6: smoked mash; S601: adding the acetic mash from step S501 into a mash smoking tank, and performing dry smoking at 45° C. on day 1 to day 2 using a mixture of bran and buckwheat hulls in a mass ratio of 3:1 as a smoke source, and controlling the humidity to 35%. On day 3 to day 5, performing wet smoking at 35° C. using a mixture of bran, sawdust, and astragalus stem and leaf powder in a mass ratio of 2:1:0.05 as a smoke source, and controlling the humidity to 65%, to obtain a smoked mash; S7: Drizzle with vinegar; S701: Place the smoked mash into a rinsing device, and circulate water spraying and pouring for 60 minutes to obtain astragalus vinegar.

[0010] Example 2: A fully solid-state astragalus vinegar fermentation process comprising the following steps: S1: soaking and enzymatic pretreatment; S101: The crushed sorghum, astragalus powder and returned grains were mixed in a mass ratio of 10:1:30, and a pre-prepared slow-release enzyme solution was added. The mixture was soaked in water for 11 hours, with the pH at 8.0 and the temperature at 42°C maintained during this stage. The moisture content of the blank was initially adjusted to 62%, thereby obtaining a soaked material. The slow-release enzyme solution is prepared by adding 0.5% cellulase and 0.3% pectinase to a phosphate buffer solution preheated at 40°C, stirring and dissolving uniformly, and then standing at 45°C for 10 minutes; the cellulase activity is 5×10 4 U / g; the pectinase activity is 10 5 U / g; S2: layered cooking with humidity gradient; S201: Add equal amounts of the soaking material from step S101 into a steamer in three layers. Spray each layer with moisture before steaming. Steam in stages: the first stage (30 minutes), humidity (65%), temperature (100°C); the middle stage (30 minutes), humidity (60%), temperature (100°C); and the last stage (30 minutes), humidity (55%), temperature (100°C). S3: Mixing materials and inoculating bacteria at different times; S301: When the steamed material in step S201 is cooled to 50° C., 40% of the mass of Daqu and 20% of the mass of Wenqu (gluten) are added, the mixture is evenly mixed, the temperature is lowered to 25° C., 4% of thermophilic yeast is inoculated, and pre-fermentation is carried out for 12 hours. 1.5% of acetic acid bacteria is spray-inoculated to obtain a mixed material; S4: alcoholic fermentation; S401: Add the mixed material from step S301 to an alcohol fermentation tank, sprinkle rice husks and bamboo charcoal powder on the surface, cover with bran and plastic sheeting to seal, and ferment in stages. On days 1 to 2, control the temperature at 33°C, and on days 3 to 8, control the temperature at 24°C and pH at 6.2. After fermentation, measure the alcohol content of the mash, which is 5%, to obtain an alcohol fermented mash. S5: acetic acid fermentation; S501: Take the alcohol fermentation mash from step S401, mix it with 20% of the main material weight of rice husk, 105% of bran, 0.8% of diatomaceous earth and 0.2% of a mineral slow-release bag, place it in an acetic acid fermentation tank, cover it with a breathable straw mat, and ferment it in stages. On the 1st to 4th day, control the temperature at 46°C and turn the tank every 12 hours; on the 5th to 7th day, control the temperature at 43°C and turn the tank every 24 hours; on the 8th to 9th day, control the temperature at 39°C and turn the tank every 24 hours to obtain acetic acid mash; The specific preparation steps of the mineral sustained-release package are as follows: S1001: Dissolve 1.38 g of potassium dihydrogen phosphate, 0.9 g of magnesium sulfate, 0.36 g of zinc sulfate, 0.18 g of iron sulfate, 0.09 g of manganese sulfate, and 0.09 g of copper sulfate in 100 mL of deionized water and stir for 20 min to obtain a 30 g / L mineral solution; S1002: 8 g of food-grade hydroxypropyl methylcellulose and 2 g of chitosan were dissolved in 90 mL of 1.5% acetic acid water and spray-dried at 75°C to obtain hollow microspheres. 10 g of the hollow microspheres were then added to 60 mL of the mineral solution obtained in step S1001 and subjected to cyclic adsorption at 60°C for 60 min, followed by removal to obtain adsorbed microspheres. S1003: 10 g of the adsorption microspheres from step S1002 were added to 55 mL of 0.2% sodium alginate solution and dispersed evenly. 65 mL of 1.5% CaCl2 solution was then added dropwise. After cross-linking treatment for 18 minutes, the microspheres were removed, vacuum-dried at 40°C for 15 hours, crushed and screened through a 16-mesh filter to obtain a mineral sustained-release package. S6: smoked mash; S601: adding the acetic mash material from step S501 into a mash smoking tank, and performing dry smoking at 48° C. on day 1 to day 2 using a mixture of bran and buckwheat hulls in a mass ratio of 3:1 as a smoke source, and controlling the humidity to 38%. On day 3 to day 5, performing wet smoking at 38° C. using a mixture of bran, sawdust, and astragalus stem and leaf powder in a mass ratio of 2:1:0.05 as a smoke source, and controlling the humidity to 68%, to obtain a smoked mash; S7: Drizzle with vinegar; S701: Place the smoked mash into a rinsing device, and circulate water spraying and pouring for 60 minutes to obtain astragalus vinegar.

[0011] Example 3: A fully solid-state astragalus vinegar fermentation process comprising the following steps: S1: soaking and enzymatic pretreatment; S101: The crushed sorghum, astragalus powder and returned grains are mixed in a mass ratio of 10:1:30, and a pre-prepared slow-release enzyme solution is added. The mixture is soaked in water for 10 hours, maintaining the pH at 8.0 and the temperature at 45°C. During this stage, the moisture content of the billet reaches 65% to obtain a soaked material; The slow-release enzyme solution is prepared by adding 0.5% cellulase and 0.3% pectinase to a phosphate buffer solution preheated at 40°C, stirring and dissolving uniformly, and then standing at 45°C for 10 minutes; the cellulase activity is 5×10 4 U / g; the pectinase activity is 10 5 U / g; S2: layered cooking with humidity gradient; S201: Add equal amounts of the soaking material from step S101 into a steamer in three layers. Spray each layer with moisture before steaming. Steam in stages: the first stage (30 minutes), humidity (65%), temperature (100°C); the middle stage (30 minutes), humidity (60%), temperature (100°C); and the last stage (30 minutes), humidity (55%), temperature (100°C). S3: Mixing materials and inoculating bacteria at different times; S301: When the steamed material in step S201 is cooled to 50° C., 40% of the mass of the main material, Daqu, and 20% of the mass of the main material, Wenqu, are added, mixed, cooled to 25° C., inoculated with 5% of thermophilic yeast, pre-fermented for 12 hours, and spray-inoculated with 2% of acetic acid bacteria to obtain a mixed material; S4: alcoholic fermentation; S401: Add the mixed material from step S301 to an alcohol fermentation tank, sprinkle rice husks and bamboo charcoal powder on the surface, cover with bran and plastic sheeting to seal, and ferment in stages. On the first and second days, the temperature is controlled at 35°C, and on the third to eighth days, the temperature is controlled at 25°C, and the pH is controlled at 6.0. After fermentation, the alcohol content of the mash is measured and is 6.5%, thereby obtaining an alcohol fermented mash; S5: acetic acid fermentation; S501: Take the alcohol fermentation mash from step S401, mix it with 20% of the main material weight of rice husk, 110% of bran, 1% of diatomaceous earth and 0.3% of a mineral slow-release bag, place it in an acetic acid fermentation tank, cover it with a breathable straw mat, and ferment it in stages. On the 1st to 4th day, control the temperature at 48°C and turn the tank every 12 hours; on the 5th to 7th day, control the temperature at 44°C and turn the tank every 24 hours; on the 8th to 9th day, control the temperature at 40°C and turn the tank every 24 hours to obtain acetic acid mash; The specific preparation steps of the mineral sustained-release package are as follows: S1001: Dissolve 1.38 g of potassium dihydrogen phosphate, 0.9 g of magnesium sulfate, 0.36 g of zinc sulfate, 0.18 g of iron sulfate, 0.09 g of manganese sulfate, and 0.09 g of copper sulfate in 100 mL of deionized water and stir for 20 min to obtain a 30 g / L mineral solution; S1002: 8 g of food-grade hydroxypropyl methylcellulose and 2 g of chitosan were dissolved in 100 mL of 1.5% acetic acid water and spray-dried at 75°C to obtain hollow microspheres; then 10 g of the hollow microspheres were added to 80 mL of the mineral solution obtained in step S1001, and the mixture was adsorbed at 60°C for 50 min before being removed to obtain adsorbed microspheres; S1003: 10 g of the adsorption microspheres from step S1002 were added to 50 mL of 0.2% sodium alginate solution and dispersed evenly. 60 mL of 1.5% CaCl2 solution was then added dropwise. After cross-linking treatment for 20 min, the microspheres were removed and vacuum-dried at 40°C for 16 h. The microspheres were crushed and screened through a 16-mesh filter to obtain a mineral sustained-release package. S6: smoked mash; S601: adding the acetic mash material from step S501 into a mash smoking tank, and performing dry smoking at 50° C. on the first to second days using a mixture of bran and buckwheat hulls in a mass ratio of 3:1 as a smoke source, with the humidity controlled at 40%. On the third to fifth days, performing wet smoking at 40° C. using a mixture of bran, sawdust, and astragalus stem and leaf powder in a mass ratio of 2:1:0.05 as a smoke source, with the humidity controlled at 70%, to obtain smoked mash; S7: Drizzle with vinegar; S701: Place the smoked mash into a rinsing device, and circulate water spraying and pouring for 60 minutes to obtain astragalus vinegar.

[0012] Comparative Example 1: The operation process of Comparative Example 1 is basically the same as that of Example 3, except that, in step S1 of Comparative Example 1, no slow-release enzyme solution is added, but water is directly used for soaking.

[0013] Comparative Example 2: The operating procedures of Comparative Example 2 are basically the same as those of Example 3, except that, in step S4 of Comparative Example 2, the alcohol fermentation is kept at a constant temperature of 30°C throughout the entire process; and in step S5 of acetic acid fermentation, the temperature is kept at a constant temperature of 42°C throughout the entire process, instead of staged gradient temperature control.

[0014] Performance testing: Microbial testing: The astragalus vinegar samples prepared in Examples 1 to 3 and Comparative Examples 1 to 2 were tested for Escherichia coli according to GB 4789.38-2012; for Salmonella according to GB 4789.4-2016; and for Staphylococcus aureus according to GB 4789.10-2016. The test results are shown in Table 1 below.

[0015]

[0016] As shown in Table 1, the astragalus vinegar prepared by the present invention was not contaminated by microorganisms, and there was no bacterial contamination in the entire preparation process. It is safe and reliable and meets food safety standards.

[0017] Flavor test: 20 volunteers were selected to taste the astragalus vinegar prepared in Example 3, Comparative Examples 1-2, and the control group (conventional semi-solid process brewing), and then each person scored the astragalus vinegar prepared in Example 3 and Comparative Examples 1-2, respectively, from three aspects: aroma (30%), appearance (20%), and taste (50%). The scores ranged from 1 to 10, with 10 being the best. The scoring results were averaged, and the total score was the weighted average. The results were rounded to one decimal place. The results are shown in Table 2 below.

[0018]

[0019] As can be seen from the results in Table 2, the astragalus vinegar prepared by the process of the present invention exhibits excellent flavor characteristics and has received good reviews in terms of taste. As can be seen from the results of Comparative Example 1, the absence of cellulase and pectinase leads to insufficient decomposition of the cell walls of astragalus powder and sorghum, and insufficient release of medicinal aroma substances and ester precursors. In addition, the residual unhydrolyzed starch and cellulose increase the granularity of the vinegar liquid, and the content of flavor esters such as ethyl acetate in the fermentation product is reduced. The absence of pectinase leads to a higher viscosity of the mash and a decrease in light transmittance after vinegar is poured. As can be seen from the results of Comparative Example 2, constant temperature alcohol fermentation inhibits the staged metabolism of thermophilic yeast, resulting in a decrease in ester diversity. Constant temperature acetic acid fermentation causes overactivity of acetic acid bacteria, and the excessively high proportion of acetic acid masks other flavors. In addition, the lack of staged temperature control leads to insufficient production of mild acids such as lactic acid, an increased irritation of the taste, and a significant decrease in taste.

[0020] Total acid content and pH determination: According to GB 12456-2021, the total acid of the astragalus vinegar brewed in Example 3, Comparative Examples 1 to 2 and the control group (conventional semi-solid process brewing) was determined, and the pH value of the astragalus vinegar was determined using an acid-base pH meter. The total acid content and pH value determination results are as follows: Figure 1 shown.

[0021] Depend on Figure 1 The results show that the process used in the present invention promotes the balance of acetic acid and lactic acid through gradient temperature control, and the total acid content is high and appropriate; from the results of Comparative Example 1, it can be seen that the pre-hydrolysis of cellulose and pectin is missing, the release of fermentable sugars is reduced, and the subsequent ethanol / acetic acid production is inhibited; from the results of Comparative Example 2, it can be seen that constant temperature accelerates the metabolism of acetic acid bacteria, which may lead to excessive accumulation of acetic acid, and thus lead to excessively high total acid content.

[0022] While embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions, and variations may be made to these embodiments without departing from the principles and spirit of the invention, and that the scope of the invention is defined by the appended claims and their equivalents.

Claims

1. A fully solid-state astragalus vinegar fermentation process, characterized in that: The steps include: S1: soaking and enzymatic pretreatment; S2: layered cooking with humidity gradient; S3: Mixing materials and inoculating bacteria at different times; S4: alcoholic fermentation; S5: acetic acid fermentation; S6: smoked mash; S7: Drizzle with vinegar.

2. A full-solid-state astragalus vinegar fermentation process according to claim 1, characterized in that, In step S1, the specific operations of the soaking material and enzymatic pretreatment are as follows: S101: mixing the crushed sorghum, astragalus powder and the returned lees in proportion, adding a pre-prepared slow-release enzyme solution, soaking in water, maintaining a certain pH and temperature, and increasing the moisture content of the billet to obtain a soaked material; In step S101, the slow-release enzyme solution is prepared by adding 0.5% cellulase and 0.3% pectinase to a phosphate buffer solution preheated at 40°C, stirring and dissolving them uniformly, and then standing at 45°C for 10 minutes; the cellulase activity is 5×10 4 U / g; the pectinase activity is 10 5 U / g.

3. A full-solid-state astragalus vinegar fermentation process according to claim 2, characterized in that, In step S2, the specific operations of the layered cooking and humidity gradient are as follows: S201: adding equal amounts of the soaking material from step S101 into a steamer in three layers, spraying each layer with moisture before steaming, and steaming in stages to obtain steamed material; In step S201, the specific operation of the staged cooking is: the first stage is 30 minutes, the humidity is 65%, and the temperature is 100°C; the middle stage is 30 minutes, the humidity is 60%, and the temperature is 100°C; and the last stage is 30 minutes, the humidity is 55%, and the temperature is 100°C.

4. A full-solid-state astragalus vinegar fermentation process according to claim 3, characterized in that, In step S3, the specific operations of mixing the materials and inoculating the strains at different times are as follows: S301: Cool the steamed material in step S201, add Daqu and Wenqu, mix well, continue to cool, then inoculate with thermophilic yeast, perform pre-fermentation, and then spray-inoculate with acetic acid bacteria to obtain mixed material.

5. A full-solid-state astragalus vinegar fermentation process according to claim 4, characterized in that, In step S4, the specific operation of the alcohol fermentation is as follows: S401: adding the mixture from step S301 into an alcohol fermentation tank, sprinkling rice husks and bamboo charcoal powder on the surface, covering with bran and plastic sheeting to seal, and fermenting in stages. After fermentation, measuring the alcohol content of the mash to obtain alcohol fermented mash; In step S401, the mass ratio of the rice husk to the bamboo charcoal powder is 4 to 6:1; In step S401, the specific operation of the staged fermentation is: on the 1st to 2nd day, the temperature is controlled at 32-35°C; on the 3rd to 8th day, the temperature is controlled at 23-25°C, and the pH is controlled at 6.0-6.

5.

6. A full-solid-state astragalus vinegar fermentation process according to claim 5, characterized in that, In step S5, the specific operation of the acetic acid fermentation is as follows: S501: Take the alcohol fermentation mash from step S401, mix it with rice husk, bran, diatomaceous earth and mineral slow-release bag, place it in an acetic acid fermentation tank, cover it with breathable straw mat, and ferment it in stages to obtain acetic acid mash.

7. A full-solid-state astragalus vinegar fermentation process according to claim 6, characterized in that: In step S501, the specific preparation steps of the mineral sustained-release package are as follows: S1001: dissolving potassium dihydrogen phosphate, magnesium sulfate, zinc sulfate, iron sulfate, manganese sulfate, and copper sulfate in deionized water, stirring to obtain a mineral solution; S1002: dissolving food-grade hydroxypropyl methylcellulose and chitosan in acetic acid water and spray drying to obtain hollow microspheres; then placing the hollow microspheres into the mineral solution of step S1001, and removing them after cyclic adsorption treatment to obtain adsorbed microspheres; S1003: adding the adsorption microspheres from step S1002 into the sodium alginate solution and dispersing them evenly, then dropping the CaCl2 solution, removing the microspheres after cross-linking, vacuum drying, crushing and screening to obtain a mineral sustained-release package.

8. A full-solid-state astragalus vinegar fermentation process according to claim 7, characterized in that: In step S1001, the mass ratio of the potassium dihydrogen phosphate, magnesium sulfate, zinc sulfate, iron sulfate, manganese sulfate and copper sulfate is 46:30:12:6:3:3; in step S1002, the mass ratio of the hydroxypropyl methylcellulose, chitosan and acetic acid water is 4g:1g:40-50mL; the mass ratio of the hollow microspheres and the mineral solution is 1g:5-8mL; in step S1003, the mass ratio of the adsorption microspheres, sodium alginate solution and CaCl2 solution is 1g:4.5-5.5mL:5.5-6.5mL.

9. A full-solid-state astragalus vinegar fermentation process according to claim 8, characterized in that: In step S501, the specific operation of the staged fermentation is as follows: on the 1st to 4th day, the temperature is controlled at 45-48°C, and the tank is turned over once every 12 hours; on the 5th to 7th day, the temperature is controlled at 42-44°C, and the tank is turned over once every 24 hours; on the 8th to 9th day, the temperature is controlled at 38-40°C, and the tank is turned over once every 24 hours.

10. The all-solid-state astragalus vinegar fermentation process according to claim 9, characterized in that: In step S6, the specific operation of smoking the mash is as follows: S601: adding the acetic mash material from step S501 into a mash smoking tank, performing dry smoking on the first to second days, and wet smoking on the third to fifth days to obtain smoked mash; In step S601, the smoke source used in the dry smoking is obtained by mixing bran and buckwheat husk in a mass ratio of 3:1; the smoke source used in the wet smoking is obtained by mixing bran, sawdust and astragalus stem and leaf powder in a mass ratio of 2:1:0.05; In step S7, the specific operation of pouring vinegar is as follows: S701: The smoked mash is placed into a rinsing device, and water is sprayed and rinsed in a circular manner to obtain astragalus vinegar.

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